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SpaceX Vehicles and Missions => SpaceX Starship Program => Topic started by: Lumina on 10/11/2016 10:50 pm

Title: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/11/2016 10:50 pm
(This is a splinter topic from the IAC discussion thread which started with the below post:)
http://forum.nasaspaceflight.com/index.php?topic=41249.msg1597551#msg1597551

From what we have learned from IAC speech, we can probably safely assume that:

(a) ITS won't be carrying ready-made tuna can habitats to Mars (there is no pod-dropping)
(b) There is no need to carry ready-made habs (wedge, or any other shape) because the ITS itself can serve as a temporary hab on Mars
(c) Habitat components will be delivered flat-packed for assembly on Mars (like all other cargo)

These assumptions lead to the conclusion that the very first humans on Mars (on a long-stay mission) will be building habitats. Agree / disagree with this conclusion?

What kind of amazing, spacious habitats can we envision? What selection of habitat building components would you want in your flat-packed containers?
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/12/2016 02:23 am
Last year NASA ran a competition for habs called the '3-D Printed Habitat Challenge'. There was only $40K up for grabs but some interesting designs were put forwards. There is some background in the article NASA Awards Top Three Design Finalists in 3-D Printed Habitat Challenge (http://www.nasa.gov/directorates/spacetech/centennial_challenges/3DPHab/2015winners.html). It's probably worth a trawl through to grab ideas.

The winning design was the Mars Ice House (http://www.marsicehouse.com/), which is well worth a look.

 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/12/2016 04:00 am
The ice-house idea is nonsense, sadly NASA seemed to have based the award on how much like of a modern architecture monstrosity it would be, note that this idea cooked up by just such an architectural firm.

A building made of ice would by necessity have walls and air at freezing temperatures inside at all times and that would raise the metabolic requirements of anyone living in it to two or three times the normal calorie intake because the body must generate so much more heat.  The interior air's moisture will freeze out as layer of frost on to the interior much like the frost in a refrigerator, ruining the 'view' and making the air extremely dry and uncomfortable.  This frost will need to be constantly scraped off or else it will just grow forever and fill the habitat.  The incredible mass of all this ice is likely to cause ground subsidence and cracking in the ice walls.  Dust accumulation on the exterior will likewise rapidly render the interior dark.

When NASA puts a stamp of approval on nonsense like this it encourages space-cadet type thinking in all kinds of other areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/12/2016 06:15 am

Basically impossible to discuss without knowing the effect of partial gravity on human health.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sdsds on 10/12/2016 06:52 am
Basically impossible to discuss without knowing the effect of partial gravity on human health.

Another fundamental health issue linked to habitat design is space radiation. It might end up that long term Mars residents do best when living in pits dug into the regolith, or at least in trenches.
Title: Re: Envisioning Amazing Martian Habitats
Post by: pietro on 10/12/2016 07:38 am
One thing is the habitat itself. Another is the interior. What if the 2-3 m3 travelling-rooms (like the Japanese capsule/tube hotels) could be removed at the end of the trip from the ITS and transferred to the new habitats? At least for the initial rounds this would make creating the sleeping spaces very easy (until bigger rooms can be provided) and efficient, would make the ITS lighter for the return leg, etc. They could be stacked (again, like in the capsule hotels, or like in The Fifth Element).

Edit:

There are some spectacular capsule hotel ideas around: https://www.google.com/search?q=capsule+hotel&tbm=isch

These could be made robust enough to connect to a central air recycling system, so that they could be used as temporary safehouses in case of a depressurization event.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 09:49 am
The ice-house idea is nonsense, sadly NASA seemed to have based the award on how much like of a modern architecture monstrosity it would be, note that this idea cooked up by just such an architectural firm.

A building made of ice would by necessity have walls and air at freezing temperatures inside at all times and that would raise the metabolic requirements of anyone living in it to two or three times the normal calorie intake because the body must generate so much more heat.  The interior air's moisture will freeze out as layer of frost on to the interior much like the frost in a refrigerator, ruining the 'view' and making the air extremely dry and uncomfortable.  This frost will need to be constantly scraped off or else it will just grow forever and fill the habitat.  The incredible mass of all this ice is likely to cause ground subsidence and cracking in the ice walls.  Dust accumulation on the exterior will likewise rapidly render the interior dark.

When NASA puts a stamp of approval on nonsense like this it encourages space-cadet type thinking in all kinds of other areas.

Insulation like expanded polystyrene (Styrofoam) could be produced from local resources too, it's just chains of C and H and you will produce lots of both all the time. If you have energy, water and CO2 all kinds of plastics will be easier to synthesize than to bring them from Earth. Building structural components for pressure vessels from ice will be impossible though. Melting caves in a glacier not so much. You will have to have enough ice above and around you to counter 10t per square meter of pressure if you want to build with ice.

I think that you will just NEED to build your habitats from local resources. Bringing them in one piece or in components from Earth will be prohibitively expensive, you will need all the payload capacity you have for other things.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 10:37 am
One thing is the habitat itself. Another is the interior. What if the 2-3 m3 travelling-rooms (like the Japanese capsule/tube hotels) could be removed at the end of the trip from the ITS and transferred to the new habitats? At least for the initial rounds this would make creating the sleeping spaces very easy (until bigger rooms can be provided) and efficient, would make the ITS lighter for the return leg, etc. They could be stacked (again, like in the capsule hotels, or like in The Fifth Element).

Edit:

There are some spectacular capsule hotel ideas around: https://www.google.com/search?q=capsule+hotel&tbm=isch

These could be made robust enough to connect to a central air recycling system, so that they could be used as temporary safehouses in case of a depressurization event.

A room is not a pressure vessel. To judge how such a room would look (and how complex it would be and what mass it would require), look at ISS modules. Apart from some differences with thermal management it's pretty much the same challenge. Things don't are easier on Mars than they are in LEO just because it is a planet.

Only if you use local resources you don't have in space things may be easier than there. If you don't do that your Mars base will look very similar to the ISS, just sitting on the ground on Mars.

Title: Re: Envisioning Amazing Martian Habitats
Post by: redliox on 10/12/2016 10:39 am
I think that you will just NEED to build your habitats from local resources. Bringing them in one piece or in components from Earth will be prohibitively expensive, you will need all the payload capacity you have for other things.

Well inevitably the first habitats on Mars will be Earth-made, but I refer to the first landings and the first teams to explore but then get down to the serious construction.  Once you have the equipment to shove regolith around and hopefully funnel it into 3D printing machines things open up.  The initial tin cans and inflatable tents might handle on the order of 3-10 people, whereas an actual city must house hundreds and eventually thousands onward.

My guess for the overall design of say a medium-sized settlement (or a very large base camp) with ~200 people would be the following:
1) Roomy but claustrophobic living space; no windows lots of dirt covering a 3D built structure.
2) Numerous garden areas, possibly domes, but primarily for plants to take advantage of natural sunlight.
3) Handful of metal nodes, such as airlocks or power systems, peaking out; mainly delivered from Earth but slowly becoming Martian-built.
In short, there would be lots of squat, building-sized mounds with greenhouses.

They would be this way because the safest landing sites probably will be in flat, boring areas with little else but the materials to build structures from.  No caves, lava tubes, or cliffs...just you, your machinery, and the dirt.  Hence why we might see slightly-boring-looking mounds for buildings on Mars...at least until you get a large enough population that starts barking for window space, then it may get more exotic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TheTraveller on 10/12/2016 10:39 am
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/12/2016 11:20 am
Well the thing about ice houses is that you are going to get large hollowed out glaciers as a result of h20 mining. So the caverns will be there whether you decide to habitat them or not.

So it really comes down to what is the most efficient in automation and equipment to convert glacier to liquid water. It might be long bore holes or it could be large caverns. One of them provides instant buildable structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 11:34 am
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.



Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 11:50 am
I think that you will just NEED to build your habitats from local resources. Bringing them in one piece or in components from Earth will be prohibitively expensive, you will need all the payload capacity you have for other things.

Well inevitably the first habitats on Mars will be Earth-made, but I refer to the first landings and the first teams to explore but then get down to the serious construction.  Once you have the equipment to shove regolith around and hopefully funnel it into 3D printing machines things open up.  The initial tin cans and inflatable tents might handle on the order of 3-10 people, whereas an actual city must house hundreds and eventually thousands onward.

My guess for the overall design of say a medium-sized settlement (or a very large base camp) with ~200 people would be the following:
1) Roomy but claustrophobic living space; no windows lots of dirt covering a 3D built structure.
2) Numerous garden areas, possibly domes, but primarily for plants to take advantage of natural sunlight.
3) Handful of metal nodes, such as airlocks or power systems, peaking out; mainly delivered from Earth but slowly becoming Martian-built.
In short, there would be lots of squat, building-sized mounds with greenhouses.

They would be this way because the safest landing sites probably will be in flat, boring areas with little else but the materials to build structures from.  No caves, lava tubes, or cliffs...just you, your machinery, and the dirt.  Hence why we might see slightly-boring-looking mounds for buildings on Mars...at least until you get a large enough population that starts barking for window space, then it may get more exotic.
The best would be a very boring site right next to a nice water cliff.  Always easier to have gravity on your side, and bringing down a cliff is easier than digging a hole.
Fortunately, there seems to be quite a few glaciers at interesting latitudes on Mars.  These glaciers may be the equivalent of river junctions on Earth; rare but that's where all the cities are/ will be.
After all, you just need a single adequate emplacement.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 11:55 am
There probably already is a thread about lava tubes, somewhere on the site?
Anyone have a link?  That could be amazing and spectacular.
Title: Re: Envisioning Amazing Martian Habitats
Post by: zodiacchris on 10/12/2016 11:56 am
Well, a naturally occurring fibre available on Mars would likely be the mineral asbestos. Once you have located a deposit you have to crush it to liberate the fibres. Great stuff, non flammable, great insulator for heat sources etc, but of course the carcinogenic properties when inhaled pretty much rule it out. :(
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 12:19 pm
There probably already is a thread about lava tubes, somewhere on the site?
Anyone have a link?  That could be amazing and spectacular.

Lava tubes would be great, but you'd need to find one near water. The places with water (as pure as possible and as much as possible) is where you have to go to, there's no way around that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 12:35 pm
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.

Thermal management will just be one of the problems you will have to solve. But if you're sitting in the midst of a glacier stretching for tens of miles and half a mile thick, some water coolant loops that dump the heat somewhere else (or heat your insulated fish pool) shouldn't be that hard. It's basically only slightly used energy, you will find a use for it...
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/12/2016 01:38 pm
Method only works at high altitudes on Mars.
ot be the safest place to live.

The Hellas glacier I thought was very low altitude and about 30-40 deg latitude.
It sounds like a great place for lots of water.
Great sun for power.
Low altitude for plenty of atmosphere.

Was also where they did the study to indicate glaciers under modest dirt overlay.

https://en.wikipedia.org/wiki/Hellas_quadrangle
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 01:58 pm
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.

Thermal management will just be one of the problems you will have to solve. But if you're sitting in the midst of a glacier stretching for tens of miles and half a mile thick, some water coolant loops that dump the heat somewhere else (or heat your insulated fish pool) shouldn't be that hard. It's basically only slightly used energy, you will find a use for it...
People who lives in meltable houses need to worry about heat ;-)
In a more serious vein (of underground water) coolant loops and piping can get expensive.  You can simply dump melted water into the atmosphere, where it will sublimate nicely enough.  Should just need a fairly small pool.  but you can't cool your ice house with liquid water, since it is necessarily hotter than the ice.  You would need to use salt water (brine), or a glycol.  then you will be using salt and recycling it, which can get intensive on a large scale.
Or you can use large arrays of piping, but large arrays of piping are extremely expensive, just talk to geothermal heat pump vendors...
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/12/2016 02:06 pm
People who lives in meltable houses need to worry about heat ;-)
In a more serious vein (of underground water) coolant loops and piping can get expensive.  You can simply dump melted water into the atmosphere, where it will sublimate nicely enough.  Should just need a fairly small pool.  but you can't cool your ice house with liquid water, since it is necessarily hotter than the ice.  You would need to use salt water (brine), or a glycol.  then you will be using salt and recycling it, which can get intensive on a large scale.
Or you can use large arrays of piping, but large arrays of piping are extremely expensive, just talk to geothermal heat pump vendors...

Well at least they could be below zero storage and play and refuge from radiation areas.
Also as mentioned above they should be able to be pressurized and provide a play area.
But above zero temperatures does provide problems.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 02:43 pm
Ice Dome Construction for Large Scale Habitats on Atmosphere Less Bodies

as attached with examples
Method only works at high altitudes on Mars.
You need to insulate the dome if you want to have above 0 temperatures inside.
I believe there is a limit to the altitude the ITS can land because it requires aerodynamic braking.  Do the two match up?
On the other hand, the mechanical characteristics of ice can be improved significantly by additives, to create a material similar to fiber reinforce plastics, Pykrete.  The same dome could be build from the outside, rather than from the inside, using hoses and a supply of fibrous material. 
Wouldn't be transparent, though, although perhaps translucent, depending on the fiber used.
What is the cheapest fiber than can be obtained/produced on Mars?

What is the heat balance of a Martian building?  Houses are not very energy intensive, but the heat load from an efficient plantation may be quite high, for example.  A greenhouse (or more aptly a grow house) in ice might be a significative challenge, at the lighting levels can reach hundreds of watts per m2.  Intensive grow houses on Earth require active cooling. 
So you may have a cheap building, but if it requires constant active cooling and a radiative cooling system, it may not be the safest place to live.

Thermal management will just be one of the problems you will have to solve. But if you're sitting in the midst of a glacier stretching for tens of miles and half a mile thick, some water coolant loops that dump the heat somewhere else (or heat your insulated fish pool) shouldn't be that hard. It's basically only slightly used energy, you will find a use for it...
People who lives in meltable houses need to worry about heat ;-)
In a more serious vein (of underground water) coolant loops and piping can get expensive.  You can simply dump melted water into the atmosphere, where it will sublimate nicely enough.  Should just need a fairly small pool.  but you can't cool your ice house with liquid water, since it is necessarily hotter than the ice.  You would need to use salt water (brine), or a glycol.  then you will be using salt and recycling it, which can get intensive on a large scale.
Or you can use large arrays of piping, but large arrays of piping are extremely expensive, just talk to geothermal heat pump vendors...

You can dump a lot of heat into ice that is at -50°C without melting it. Well, I'm still at the glacier idea and not at ice domes of course... If you have enough water, you can even use sublimation cooling as the Apollo suits used on the Moon. And what you need to cool is not the house, but either the air in it or the equipment and all of this will necessarily be above the freezing point of water. The ice will need to be insulated anyway.

And whatever you do, thermal management will be a thing you have to care for, but this much easier on Mars than in space where you can only radiate heat away or evaporate water (which you will have only a very limited supply of).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/12/2016 03:26 pm
I find this thread would be more fun and Amazing if we thought and planed for the larger scale installations required for 1 million colonists.

We could skip the first 20 years, that are probably going to be systems that are prefabricated and come from Earth, and think about the longer term, large scale infrastructures?

-Can you fit one million people and their food production systems in a glacier?  How long will the heat sink last?
-How far away can resources be?
-What is the energy required?
-How large will the spaceport be?
-What will be the ground level infrastructures?
-What is a good size for a community in the Mars environment?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/12/2016 04:44 pm
It really depends on where on Mars the base is and what the local resources and circumstances are.

For Hellas basin glaciers covered in a few meters of Regolith, assuming it's a relatively pure water ice glacier, maybe designs that consume the ice of the glacier, taking advantage of the thicker atmosphere in the Hellas basin. As the ice is consumed for ISRU propellant, oxygen and water, the void created might be living space. The regolith cap might be held in place both by mixing with water and freezing it and building support structure.

There's room for very large underground spaces to be hollowed out since the glaciers are hundreds of meters thick and cover square kilometers. The roof over the space would be controlled architecture using regolith rather than depending on something like lava tubes natural roof. Since the roof is designed it could be strong enough to support suspended structures hanging from it.

The space would grow as a side effect of consuming the ice anyway so the main design decision would be what shape to make the cavity.

I picture a growing vertical space that gets to be over 300m deep before hitting rock. There might be a truss structure on the surface to allow suspending structures in the space. Eventually you could have a huge 3D space with structures coming up from the floor, suspended from the roof and built into the rock walls of the cavity.

At Mars gravity with sea level air pressure flight is very easy so a main mode of transport in the space is flying. There are light airy buildings with 100 levels and lots of open balconies (that people can fly to) looking out on a vast 3D cityscape. Lower gravity, suspension from the roof and materials like carbon fiber allow pretty amazing architectural expression not seen on earth. You take an elevator to the floor which is parklike and includes lakes or the Mars surface above which is mostly industrial and utilitarian.

No idea how stable the glacier is or how much it flows. I'm assuming there's a site where there's a buried Glacier that's pretty static by earth standards. The low gravity and lack of new snowfall ought to promote stability.

I think any civilization on Mars depends on plentiful energy. Hellas is near the equator so good for solar. I think nuclear is needed anyway.

I think the best middle term chance at building pleasant environments on Mars is with large open underground spaces that permit O'Neill colony like landscapes with trees and open water. Building within the voids creating by mining glaciers in Hellas might permit this with decent intermediate designs, in a space that's being created anyway and a location that has many advantages.

If residents like the idea of natural sunlight, it can be collected on the surface and piped in. The roof isn't very thick and it's not difficult. The roof is sufficient though to protect against radiation.

A single glacier in the Hellas basin could easily hold a city of million people in this mode. At some point it would start piping in water from other nearby glaciers and starting suburbs.

I'm assuming that agriculture is just another industrial activity and is done in completely controlled environments with artificial light and works just as well in vertical stacks 300 meters high underground as anywhere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 05:58 pm
I find this thread would be more fun and Amazing if we thought and planed for the larger scale installations required for 1 million colonists.

We could skip the first 20 years, that are probably going to be systems that are prefabricated and come from Earth, and think about the longer term, large scale infrastructures?

-Can you fit one million people and their food production systems in a glacier?  How long will the heat sink last?
-How far away can resources be?
-What is the energy required?
-How large will the spaceport be?
-What will be the ground level infrastructures?
-What is a good size for a community in the Mars environment?

I think a million people would require at some point digging into rock, since you will need the water for other things. It would probably be a good idea to start at a place where you can spread out to other glaciers at least for producing fuel.

Energy will be tight, nuclear power would be necessary at least to buffer solar power problems from global sand storms that you'll be guaranteed to run into at some point. You solar power farms probably would be big enough to be seen from orbit ;-)

Going underground (either ice or rock) in the long run is inevitable, not only for radiation shielding but also for protection against landing and launching (and sooner or later crashing) spacecraft. I would expect very little ground-level infrastructure. Transportation may work for water (you will need thousands of tons to fuel a single ship), maybe buried and insulated pipelines. You could put some distance between your spaceport and ISRU facilities and the actual city, although transporting people and cargo over ground would be a major PITA. Expect many tunnels. Prospecting for iron for heavy machinery would have quite high priority I guess.

Managing your thermal and energy budgets wisely would be crucial, especially as both depend on each other: Any heat you have to reject by basically heating the ground, air or sky (by radiating it away) is wasted energy. Trying to do things as efficient as possible would be much more important than down here on Earth. I'm sure though that this would be easier with a million people than with a dozen (relatively, not absolutely).

You'd probably wise to simulate things beforehand, so you don't realize you've started it wrong too late...

At a million people population density would be high or you would need to spread out very far.

In situ research to find the best place before even starting is important. Even the first crews though have to start out where the water is or they and their ship will never make it back.

All of this would be a major undertaking, the biggest in the history of mankind. And building the spacecrafts would be just the feeble beginnings.

But even now you will find that people roughly fall into two groups: The first says "Why? I just want to sit on my couch, leave me alone, you're crazy!" and the second says "Hey, let's start! What do I have to do?". But I think anyway that not having anything to do is the curse of modernity...
Title: Re: Envisioning Amazing Martian Habitats
Post by: b0objunior on 10/12/2016 06:20 pm
It really depends on where on Mars the base is and what the local resources and circumstances are.

For Hellas basin glaciers covered in a few meters of Regolith, assuming it's a relatively pure water ice glacier, maybe designs that consume the ice of the glacier, taking advantage of the thicker atmosphere in the Hellas basin. As the ice is consumed for ISRU propellant, oxygen and water, the void created might be living space. The regolith cap might be held in place both by mixing with water and freezing it and building support structure.

There's room for very large underground spaces to be hollowed out since the glaciers are hundreds of meters thick and cover square kilometers. The roof over the space would be controlled architecture using regolith rather than depending on something like lava tubes natural roof. Since the roof is designed it could be strong enough to support suspended structures hanging from it.

The space would grow as a side effect of consuming the ice anyway so the main design decision would be what shape to make the cavity.

I picture a growing vertical space that gets to be over 300m deep before hitting rock. There might be a truss structure on the surface to allow suspending structures in the space. Eventually you could have a huge 3D space with structures coming up from the floor, suspended from the roof and built into the rock walls of the cavity.

At Mars gravity with sea level air pressure flight is very easy so a main mode of transport in the space is flying. There are light airy buildings with 100 levels and lots of open balconies (that people can fly to) looking out on a vast 3D cityscape. Lower gravity, suspension from the roof and materials like carbon fiber allow pretty amazing architectural expression not seen on earth. You take an elevator to the floor which is parklike and includes lakes or the Mars surface above which is mostly industrial and utilitarian.

No idea how stable the glacier is or how much it flows. I'm assuming there's a site where there's a buried Glacier that's pretty static by earth standards. The low gravity and lack of new snowfall ought to promote stability.

I think any civilization on Mars depends on plentiful energy. Hellas is near the equator so good for solar. I think nuclear is needed anyway.

I think the best middle term chance at building pleasant environments on Mars is with large open underground spaces that permit O'Neill colony like landscapes with trees and open water. Building within the voids creating by mining glaciers in Hellas might permit this with decent intermediate designs, in a space that's being created anyway and a location that has many advantages.

If residents like the idea of natural sunlight, it can be collected on the surface and piped in. The roof isn't very thick and it's not difficult. The roof is sufficient though to protect against radiation.

A single glacier in the Hellas basin could easily hold a city of million people in this mode. At some point it would start piping in water from other nearby glaciers and starting suburbs.

I'm assuming that agriculture is just another industrial activity and is done in completely controlled environments with artificial light and works just as well in vertical stacks 300 meters high underground as anywhere.
There's a third group of people, the ones that think Mars is not the solution.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RoboGoofers on 10/12/2016 06:32 pm
Somewhat jokingly: what common things would have to be reevaluated considering Mars Gravity? Earth stairs would probably be awkward. Sinks would have to be wider or deeper to catch splashing water. Walking with a cup full of water might be messy as it sloshes over the brim.

It might be impossible to assume what will work beforehand, and a comfortable solution will only be found after people get there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 08:08 pm
There's a third group of people, the ones that think Mars is not the solution.

Of course Mars isn't a solution. Mars is an interesting problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/12/2016 08:32 pm
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/12/2016 09:17 pm
I don't think there is any problems with the low temperatures on the 'shed' part of the ice house. The conditions inside that part are much better than outside. You have

* Pressure, enough not to need a pressure suit
* Breathable atmosphere
* Protection from radiation

It gives a usable space for very little landed mass.

Inside that space you have a second chamber, lets call it a 'conservatory', which is insulated with aerogel on the inner surface of the ice so to can be warmed to 20C. This be used to grow plants and as space to hang out.

Inside that you have the landed aluminium hab with all the ECLSS etc.

Unless there is some big flaw that I'm missing it seems you get a much bigger hab for very little extra landed mass.


Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/12/2016 09:38 pm
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.

Nobody is saying that habitats in ice would need to be cold. Insulating walls really isn't rocket science, even your deep freezer manages this. My house has snow on the roof in the winter without being cold inside. Polyethylene can be synthesized from hydrogen and carbon, you wouldn't even have to bring it.

Building big pressure vessels is HARD. Really. Drilling into rock or melting into ice gives you the big advantage of not having to build pressure vessels because you have all the weight of the ice or rock on top to counter the pressure. This weight comes for free, it's already there.

And with "pressure" I mean 10 tons for every square meter of your arcade trying to rip it apart from the inside. The tension the walls have to keep up against goes up proportionally with the radius of the vessel. Plastic just isn't going to work, you'll need aluminum or steel or carbon fibre, and lots of it. And you will have to build it as a sphere or a cylinder, because it will pop out immediately otherwise. And the smallest weakness somewhere can make it fail catastrophically.

And you will still have to insulate it, because the regolith on top and beneath and with it the skin of your building will be at the same temperature as the ice in a glacier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: renclod on 10/12/2016 09:49 pm
Most people crazy enough to leave Earth for Mars will treasure mobility above all else, probably. They will hate to be pinned down for long whiles. They will work on building large rovers and then move to another site.  They will build robots, start them on a site task and then move on.  Airlocks will be plenty and large mobile habs likewise, probably. For a century at least.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/13/2016 12:20 am
(Reposting from general discussion thread)

Here's my vision for amazing habitats on Mars. I imagine networks of cliffside cities with many panoramic windows dug out from mesas, natural canyon walls or even Tatooine-style dugouts, featuring:
 
- multiple levels,
- dozens of windows and dome-covered verandas with panoramic views,
- excellent protection from radiation,
- robustly stable indoor temperatures, so one less thing that can go wrong,
- shirtsleeve access via tunnels to surface facilities above or nearby (e.g. power generation, greenhouses, landing pads),
- redundant protection from decompression with segments protected by automatic airlocks,
- grand and inspiring elaborate carved entrances with inspiration from all ancient cultures on Earth,
- direct shirtsleeve access (via tunnels / airlocks) to mines for resource extraction

Besides excavation equipment and the usual internal equipment needed for habitats, the following will be needed:

- a scalable and flexible solution for a flooring and false ceiling system that can eventually use in situ resources,
- a scalable solution for sealing excavated tunnel surfaces that can also eventually use in situ resources (some kind of epoxy?),
- automatic airlocks and door systems to separate segments for safety,
- a modular system to create windows or external domes to cover "verandas", also evolvable to use in situ resources for the future.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 06:23 am
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.

I agree with most of your critique of the ice house. None of those things apply to occupying space inside a glacier. You need to insulate the ice face, but there's no reason the temperature in the space opened up inside the glacier can't be like Hawaii. If you start at the edge where the glacier meets rock and expose it as you consume the ice going down, you can build into the rock or attach to it as well as suspend structures from the roof.

I don't think any sort of surface structure can provide a pleasant or safe city environment on Mars. That requires very large open spaces with normal atmosphere and as you suggest pleasant temperatures. It all has to be shielded from surface conditions and permit construction in an earthlike "outdoor" environment.

If you build anything on the surface it has to be a separate pressure vessel. It's just incredibly wasteful of materials and effort to build tiny volumes of habitable space on the surface when you are creating a huge habitable volume that can be very efficiently pressurized as a side effect of consuming the glacier anyway. The image of ice near you suggests cold but there's no real issue with the void in the glacier being cold. The ice face just has to be insulated to protect it from the waste heat of the settlement. Unlike the icehouse design nothing is built out of ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 06:30 am
Inside that space you have a second chamber, lets call it a 'conservatory', which is insulated with aerogel on the inner surface of the ice so to can be warmed to 20C. This be used to grow plants and as space to hang out.

Growing plants inside that ice house would require tremendous energy for lighting. It would be very hard to keep temperatures low enough to not melt the ice dome. Not impossible but for greenhouses I think there would be better solutions. The plants don't need radiaton protection.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 06:32 am
(Reposting from general discussion thread)

Here's my vision for amazing habitats on Mars. I imagine networks of cliffside cities with many panoramic windows dug out from mesas, natural canyon walls or even Tatooine-style dugouts, featuring:
 
- multiple levels,
- dozens of windows and dome-covered verandas with panoramic views,
- excellent protection from radiation,
- robustly stable indoor temperatures, so one less thing that can go wrong,
- shirtsleeve access via tunnels to surface facilities above or nearby (e.g. power generation, greenhouses, landing pads),
- redundant protection from decompression with segments protected by automatic airlocks,
- grand and inspiring elaborate carved entrances with inspiration from all ancient cultures on Earth,
- direct shirtsleeve access (via tunnels / airlocks) to mines for resource extraction

Besides excavation equipment and the usual internal equipment needed for habitats, the following will be needed:

- a scalable and flexible solution for a flooring and false ceiling system that can eventually use in situ resources,
- a scalable solution for sealing excavated tunnel surfaces that can also eventually use in situ resources (some kind of epoxy?),
- automatic airlocks and door systems to separate segments for safety,
- a modular system to create windows or external domes to cover "verandas", also evolvable to use in situ resources for the future.

If you start at the edge of the glacier where it meets rock and expose the rock face as you consume the glacier you can attach to or build into the rock as well as suspend structures from the roof. The process of using the ice opens up space for this sort of thing in a volume that can have a comfortable atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 06:33 am
Moving my post from the IAC thread here.

Glaciers may move on Mars but sure at a much slower rate. The ice is much colder and harder. Also forces moving them are smaller. On earth glaciers move because they are on a slope or because there is new precipitation which produces thrust. Both would be absent or much smaller on Mars.

Habitats could be well insulated houses. The caves in the glacier could be very large so heat from the habitats can dissipate into the glacier without causing melting. The caves would be pressurized so people could be outside without spacesuit though they would need heavy arctic clothing. If temperatures could be kept at -10-15°C and the air dry, being outside could be even fun with little air movement. This would likely not be the only type of habitat but it could be one option.

I have visited a salt mine with huge caves. That should look somewhat similar and it was gorgeous.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 06:46 am
Another concept that could give wide open spaces though with columns.

Place columns made of Marscrete, reenforced with basalt fibre and space them equally in a hexagonal pattern. Build prefab hexagonal domes to place them on top of the columns. Place a regolith cover on top of the domes heavy enough to counteract pressurization. That's heavy and the columns need to be strong enough to support them. The structure should be strong enough to stand up when one column fails and needs to be replaced. That pattern can be extended gradually.

The structure would need safety features in case of breaches. It should have sections that can be sealed off. They should also have small pressurized shelters and maintain pressure when breached long enough for people to reach those shelters.

The advantage would be a large connected area where people can roam without pressure suits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 06:58 am
None of the flaws in the ice house or any other ice based structure such as inside a glacier have been addressed, the living space inside is simply uncomfortable and high maintenance on par with living in an arctic region, if your going to go to the trouble of making an enclosed space with breathable air and temperatures still substantially above the outside temperature it makes little sense to not go all the way and go to a comfortable indoor temperature.

If people want to speculate about million inhabitant level construction methods then I will give you my take.  It will consist of an arcade https://en.wikipedia.org/wiki/Arcade_(architecture) of columns and groin-vaults several stories tall and covering the ground in all directions as it grows at the edges with the first meter or two of regolith on the ground being used to make each addition.  The column interiors are regolith as is a covering over the top of all the vaults for radiation protection.  Some form of plastic, carbon-fiber or basalt fiber made from local materials is jacketed around the column to give it tensile strength and forms the vaulting as well.  Between the columns of the arcade a lattice works connect to the columns and form floor joists onto which thin bubble pressure vessels are inflated and connected to each other.  Heavy systems like liquid storage is at ground level and some kind of light-rail tram system provides horizontal transport while elevators and stairs provide vertical transport.

Nobody is saying that habitats in ice would need to be cold. Insulating walls really isn't rocket science, even your deep freezer manages this. My house has snow on the roof in the winter without being cold inside. Polyethylene can be synthesized from hydrogen and carbon, you wouldn't even have to bring it.

Building big pressure vessels is HARD. Really. Drilling into rock or melting into ice gives you the big advantage of not having to build pressure vessels because you have all the weight of the ice or rock on top to counter the pressure. This weight comes for free, it's already there.

And with "pressure" I mean 10 tons for every square meter of your arcade trying to rip it apart from the inside. The tension the walls have to keep up against goes up proportionally with the radius of the vessel. Plastic just isn't going to work, you'll need aluminum or steel or carbon fibre, and lots of it. And you will have to build it as a sphere or a cylinder, because it will pop out immediately otherwise. And the smallest weakness somewhere can make it fail catastrophically.

And you will still have to insulate it, because the regolith on top and beneath and with it the skin of your building will be at the same temperature as the ice in a glacier.

...and any "buildings" you build on the surface have these issues that have to be addressed for each structure separately. Each ends up enclosing a tiny habitable volume at great expense. Meanwhile you have to consume vast amounts of ice in the glacier just for propellant and basics leaving a huge and growing volume that's comparatively cheap and easy to pressurize and make comfortable. That space is a resource unique to this sort of location.




Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/13/2016 07:11 am
Moving my post from the IAC thread here.

Glaciers may move on Mars but sure at a much slower rate. The ice is much colder and harder. Also forces moving them are smaller. On earth glaciers move because they are on a slope or because there is new precipitation which produces thrust. Both would be absent or much smaller on Mars.

Habitats could be well insulated houses. The caves in the glacier could be very large so heat from the habitats can dissipate into the glacier without causing melting. The caves would be pressurized so people could be outside without spacesuit though they would need heavy arctic clothing. If temperatures could be kept at -10-15°C and the air dry, being outside could be even fun with little air movement. This would likely not be the only type of habitat but it could be one option.

I have visited a salt mine with huge caves. That should look somewhat similar and it was gorgeous.

This is what I was assuming about glaciers there. Without new snowfall or geological activity I'd think they'd be much slower (though it's clear from the pictures that they flow, it may not be on a human relevant timescale). I'd have to think that insulating the face of the ice from the settlement's air temperature isn't that killer an issue. A settlement with reactors and waste heat anyway could keep a huge volume at a very comfortable temperature. Reactors could be located in the rock a short distance away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 07:31 am

 I'd have to think that insulating the face of the ice from the settlement's air temperature isn't that killer an issue. A settlement with reactors and waste heat anyway could keep a huge volume at a very comfortable temperature. Reactors could be located in the rock a short distance away.

Keeping the habitats warm is not what I am concerned about. Dumping waste heat while making sure the ice won't melt is the engineering challenge IMO. That would require the ice surface to be exposed and temperatures well below freezing. People do enjoy winter temperatures and snow and ice. Though some caves may be isolated and kept warm so plants can grow.

Technical solutions to dissipate low temperature heat energy would be complex and may be prone to failure. Better to have a naturally stable system.

Having some green to walk throug is nice to have. But light for plants would introduce a lot of heat that needs to be dissipated. I am not thinking of growing much food there but plants that need little light as a public park. Plants like ferns and philodendron. Plus a few separately lighted spots for plants that grow fruit like strawberries.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/13/2016 09:36 am

 I'd have to think that insulating the face of the ice from the settlement's air temperature isn't that killer an issue. A settlement with reactors and waste heat anyway could keep a huge volume at a very comfortable temperature. Reactors could be located in the rock a short distance away.

Keeping the habitats warm is not what I am concerned about. Dumping waste heat while making sure the ice won't melt is the engineering challenge IMO. That would require the ice surface to be exposed and temperatures well below freezing. People do enjoy winter temperatures and snow and ice. Though some caves may be isolated and kept warm so plants can grow.

Technical solutions to dissipate low temperature heat energy would be complex and may be prone to failure. Better to have a naturally stable system.

Having some green to walk throug is nice to have. But light for plants would introduce a lot of heat that needs to be dissipated. I am not thinking of growing much food there but plants that need little light as a public park. Plants like ferns and philodendron. Plus a few separately lighted spots for plants that grow fruit like strawberries.

If you want a naturally stable system you can also live in, nothing on Mars will do...

Seriously, you will have to manage your temperatures (by cooling or heating) just as your atmosphere and everything else. This is true for spacecraft, for space stations as the ISS and also will be the case on Mars. Dissipating heat isn't easier in surface structures than in caves in rock or ice. In fact ice at -50°C allows dumping quite a lot of heat into it without the ice melting, making this easier than on the surface where you have to use radiators to get rid of it just like at the ISS.

In fact the ISS with its 450 tons of pressure vessels, structure, airlocks, solar panels, heat exchangers etc. for 6 people is very similar to what you would need to land on Mars for a similar habitat on the surface. Transporting pressure vessels to Mars or building them on Mars just doesn't scale and the fact that you DO have solid material like ice or rock where you can carve out your habitats is a major resource on Mars compared to empty space. And once you have set up your machinery for cutting through ice or rock you can expand for a long time.

And of course at some point you would need to grow plants (and maybe fish) for food. Either that or have all your food imported from Earth forever.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 10:13 am
If you want a naturally stable system you can also live in, nothing on Mars will do...

Seriously, you will have to manage your temperatures (by cooling or heating) just as your atmosphere and everything else. This is true for spacecraft, for space stations as the ISS and also will be the case on Mars. Dissipating heat isn't easier in surface structures than in caves in rock or ice. In fact ice at -50°C allows dumping quite a lot of heat into it without the ice melting, making this easier than on the surface where you have to use radiators to get rid of it just like at the ISS.


Yes, of course it will need heating. But with energy consumption inside the living quarters and good isolation not much.

What I mean with naturally stable is the heat flow from habitat to ice being in a range where you don't need technical intervention to keep the temperature outside the habitat and within the ice cave in a practical range. As that cave would have pressure and breathable atmosphere you can vent excess heat by opening the window like you do on earth. Just size habitat size and total energy consumption and size of the ice cave so you don't need active cooling for the cave.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/13/2016 11:08 am
If you want a naturally stable system you can also live in, nothing on Mars will do...

Seriously, you will have to manage your temperatures (by cooling or heating) just as your atmosphere and everything else. This is true for spacecraft, for space stations as the ISS and also will be the case on Mars. Dissipating heat isn't easier in surface structures than in caves in rock or ice. In fact ice at -50°C allows dumping quite a lot of heat into it without the ice melting, making this easier than on the surface where you have to use radiators to get rid of it just like at the ISS.


Yes, of course it will need heating. But with energy consumption inside the living quarters and good isolation not much.

What I mean with naturally stable is the heat flow from habitat to ice being in a range where you don't need technical intervention to keep the temperature outside the habitat and within the ice cave in a practical range. As that cave would have pressure and breathable atmosphere you can vent excess heat by opening the window like you do on earth. Just size habitat size and total energy consumption and size of the ice cave so you don't need active cooling for the cave.


Yes, over all of your habitat this should be the goal, since heat you have to remove is wasted energy. But your habitat will not be just one big cave, it will have lots of rooms and tunnels and water tanks and whatever, with some parts (storage, living quarters) only generating little heat and others (machinery, greenhouses) generating a lot, so you will have to have loops of water pipes to move the heat around from places where's too much of it (cooling them) to other places where's too little of it (heating them).

In the ideal case all of this cancels out, but I guess it will be very, very hard to plan this. Total energy consumption will not be static anyway. So you will have to have the capability to dump heat somewhere to get rid of it and also to generate heat at times where you don't generate enough.

Opening the window will be a bad idea though, losing precious oxygen and nitrogen would be bad.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/13/2016 11:24 am
So a roof of 27m thick clear ice would be self supported with 1 atm pressure inside. The roof would let natural light in. Of course if you had an air leak the roof would collapse. Is there any plants that grow at -10C?

EDIT:
Possibly little green houses so the plants can be kept warm. Up here in new hampshire they do little crop row greenhouses about 4 feet wide and 3 feet high. Just enough to keep plants warm in the winter.

Probably gone to need some sort of air conditioner to make sure excess heat doesn't melt the glacier. But air conditioning is easy...
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 11:58 am
Opening the window will be a bad idea though, losing precious oxygen and nitrogen would be bad.

The whole cave would be pressurized. And soon, if not immediately, filled with breathable air. There will be plenty of it available from fuel ISRU. Oxygen because the engines run fuel rich and the production is stochiometric. Nitrogen or a breathable mix of oxygen and argon are just a byproduct of extracting the CO2 for the Sabatier process.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RoboGoofers on 10/13/2016 04:31 pm
What about waste products from ISRU? Isn't there a lot of salt in the water on mars? What about salt bricks? If you are going to be generating waste products, you might as well find a use for them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 10/13/2016 04:51 pm
Salt is an important material to have. Using it as a building material would be a huge waste. Any salt gathered through ISRU "waste" should be stockpiled for later use.

From Wikipedia https://en.wikipedia.org/wiki/Salt :
Quote
Its major industrial products are caustic soda and chlorine, and is used in many industrial processes including the manufacture of polyvinyl chloride, plastics, paper pulp and many other products. Of the annual global production of around two hundred million tonnes of salt, only about 6% is used for human consumption.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2016 09:43 pm
Let's see how much salt would be in a large body of water. If it is from precipitation, virtually none. If it is an ancient ocean it may be more. But the oceans of earth have accumulated their salt content over billions of years from rivers. The liquid oceans of Mars did not exist that long at all. I expect that it would still even pass as drinking water, except for possible poisonous ingredients.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/13/2016 10:04 pm
Let's see how much salt would be in a large body of water. If it is from precipitation, virtually none. If it is an ancient ocean it may be more. But the oceans of earth have accumulated their salt content over billions of years from rivers. The liquid oceans of Mars did not exist that long at all. I expect that it would still even pass as drinking water, except for possible poisonous ingredients.
Don't know about salt, but the water on Mars is 5 times more enriched in deuterium than Earth water, probably through loss of hydrogen in the upper atmosphere.  Venus water has 200 times the concentration of Earth.  Water was probably liquid on Mars for quite some time, so quite a bit of leaching should have taken place, followed by evaporation.
I expect there might me very salty plains, where the water evaporated rather than froze?

Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/13/2016 11:03 pm
Opening the window will be a bad idea though, losing precious oxygen and nitrogen would be bad.

The whole cave would be pressurized. And soon, if not immediately, filled with breathable air. There will be plenty of it available from fuel ISRU. Oxygen because the engines run fuel rich and the production is stochiometric. Nitrogen or a breathable mix of oxygen and argon are just a byproduct of extracting the CO2 for the Sabatier process.

Yes, the atmosphere being 96% CO2, 2% nitrogen and 2% argon (roughly) means you will accumulate quite a bit of both. Still, to replenish your internal atmosphere you will have to store them in high pressure vessels. In the long run you'll have reserves, but for quite a while having a nice atmosphere in your habitats will be too precious to vent them. Also nitrogen is important for plants, you'll tend to not waste it.

One thing about living on Mars will be that wasting anything will be a bad thing. You'll be fighting an uphill battle against entropy all the time. Finding ways to manage things with minimal losses will be paramount.

(Actually this will be a good thing. Finding ways to deal with all this as a matter of fact on Mars will mean that you will be able to use all of this on Earth to, living without actually wasting things and destroying the eco-systems. The Martians will teach the Earthlings lessons they need to learn anyway.)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/14/2016 04:13 am
90 percent of the glacier-cave talk here sounds like it's been lifted strait from the Zygote settlement of the Mars Trilogy.  The notion that a cave itself can be a pressure vessel is deeply flawed, the rock that a glacier sits on can easily be fractured and allow air to escape, as the habitat air is warm it can cause sub-surface melting, likewise the interior air in the cave would have to be kept away from the ice roof to prevent all the issues I described earlier. 

The net effect is that your going to need to have a full top and bottom pressure envelope inside the cave, it can be thin because it dose not need protection from micrometeorites as it would exposed on the surface but the cave is really not doing anything that a architectural dome and a few meters of regolith couldn't do, and it has disadvantages too, susceptibility to creep over time, difficulty in dumping waste heat as have been mentioned, inability to use skylights or any other top-down access to the habitat area.  Probably most important is that it requires that you not perform simple surface mining of the same glacier body that your living in so as to avoid damaging your own habitat.

Construction on the surface with arches, vaults, columns and other compression load bearing structures can provide the necessary radiation protection without any of these issues.  The same thin membrane pressure vessels inflated inside these protected spaces will be necessary but this is unavoidable and a wash.  Also note that some posters have erroneously claimed that a single massive pressure vessels is more efficient then many small ones, this is a common error in thinking that the pressure vessel mass scales only with surface area, in actuality it scales with volume due to a large vessel needing a thicker wall.  Given the inherent danger, I would say death-trap-ishness, in a single pressure vessel the interconnecting of many individual pressure vessels is certainly the way to go.

Note that a livable habitat is going to consist of a LOT more mass in equipment, life-support and otherwise beyond the pressure vessel, even a pressure vessel made 100 percent from local materials will need nearly the same amount of vital equipment to shipped in.  This is the flaw in most space-cadet style housing solutions, they pretend that they are making log cabins in which just walls and roof are all that's needed and that they are saving 90 percent of the shipment mass from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/14/2016 09:26 am
Leaving aside the Zygote-style caves inside ice sheets for the moment:

Which concept would take less total labor and energy to construct for equivalent pressurized volume and level of radiation protection?

1. carving a cave out of a cliffside at a location chosen for the ideal rock properties for carving, or
2. building "temple structures" consisting of columns and arches on a flat plain and covering them with regolith.



Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 10:20 am

Yes, the atmosphere being 96% CO2, 2% nitrogen and 2% argon (roughly) means you will accumulate quite a bit of both. Still, to replenish your internal atmosphere you will have to store them in high pressure vessels. In the long run you'll have reserves, but for quite a while having a nice atmosphere in your habitats will be too precious to vent them. Also nitrogen is important for plants, you'll tend to not waste it.

It seems we have a misunderstanding. I am not suggesting wasting anything. We have a large habitat with breathable air. We have a house that is not pressurized by itself because it does not need to be. Opening the window exchanges air with the larger cave which is closed. Nothing is wasted unless you see pressurizing a large cave with breathable air is waste.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/14/2016 10:37 am
90 percent of the glacier-cave talk here sounds like it's been lifted strait from the Zygote settlement of the Mars Trilogy.  The notion that a cave itself can be a pressure vessel is deeply flawed, the rock that a glacier sits on can easily be fractured and allow air to escape, as the habitat air is warm it can cause sub-surface melting, likewise the interior air in the cave would have to be kept away from the ice roof to prevent all the issues I described earlier. 

The net effect is that your going to need to have a full top and bottom pressure envelope inside the cave, it can be thin because it dose not need protection from micrometeorites as it would exposed on the surface but the cave is really not doing anything that a architectural dome and a few meters of regolith couldn't do, and it has disadvantages too, susceptibility to creep over time, difficulty in dumping waste heat as have been mentioned, inability to use skylights or any other top-down access to the habitat area.  Probably most important is that it requires that you not perform simple surface mining of the same glacier body that your living in so as to avoid damaging your own habitat.

Construction on the surface with arches, vaults, columns and other compression load bearing structures can provide the necessary radiation protection without any of these issues.  The same thin membrane pressure vessels inflated inside these protected spaces will be necessary but this is unavoidable and a wash.  Also note that some posters have erroneously claimed that a single massive pressure vessels is more efficient then many small ones, this is a common error in thinking that the pressure vessel mass scales only with surface area, in actuality it scales with volume due to a large vessel needing a thicker wall.  Given the inherent danger, I would say death-trap-ishness, in a single pressure vessel the interconnecting of many individual pressure vessels is certainly the way to go.

Note that a livable habitat is going to consist of a LOT more mass in equipment, life-support and otherwise beyond the pressure vessel, even a pressure vessel made 100 percent from local materials will need nearly the same amount of vital equipment to shipped in.  This is the flaw in most space-cadet style housing solutions, they pretend that they are making log cabins in which just walls and roof are all that's needed and that they are saving 90 percent of the shipment mass from Earth.

I think you're confusing pressure vessels with making things gas-tight. "Arches, vaults, columns and other compression load bearing structures" won't help at all because your building will not be under compression at all. It will be under tension. The atmospheric pressure inside will try to push things apart form the inside.

Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

Cracks in rock in a cave or tunnel aren't a problem, a thin membrane to prevent gas from escaping is easy, but there is no such thing like a "thin membrane pressure vessel". In a cave the pressure would be countered by the weight of the rock above and around it. If you don't have that weight you have to counter the pressure by tension in your pressure vessel and this not going to be a thin membrane then or bricks, or anything short of steel or aluminum, or massive reinforced concrete.

And yes, you need more than just pressure vessels to live in, but they're the biggest things you need and if they fail you won't have any time to fix things, because you will be dead immediately. They are the first and most crucial thing you need. And if you want to live and grow food in them, they need to be big and you need many of them and they need to be safe.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/14/2016 10:54 am
Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

1.5g/cm^3 means 1.5t/m^3. So more like 6.67m thick for 10t. Mars gravity is only 0.38g, so more like 17.54m. Maybe it would make sense to reduce the pressure in the hab.

For a bigger habitat the excavated regolith for the cover will be smaller relative to the total excavated regolith. So I think bigger (or better deeper) is better. In theory.

Edit: Ups, corrected.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/14/2016 11:58 am

Yes, the atmosphere being 96% CO2, 2% nitrogen and 2% argon (roughly) means you will accumulate quite a bit of both. Still, to replenish your internal atmosphere you will have to store them in high pressure vessels. In the long run you'll have reserves, but for quite a while having a nice atmosphere in your habitats will be too precious to vent them. Also nitrogen is important for plants, you'll tend to not waste it.

It seems we have a misunderstanding. I am not suggesting wasting anything. We have a large habitat with breathable air. We have a house that is not pressurized by itself because it does not need to be. Opening the window exchanges air with the larger cave which is closed. Nothing is wasted unless you see pressurizing a large cave with breathable air is waste.

OK, so a big buffer of pressurized volume to dump excess heat into. I would guess just dumping into a more remote part of the glacier with water loops and heating the ice there a bit would be easier, but on the other hand you will be carving out bigger and bigger caves all the time anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/14/2016 12:38 pm
There are clear advantages to having enormous spaces. A not-so-obvious advantage is that all other things being equal, the greater the enclosed volume, the slower the rate of change in the proportions of the gases in the (well mixed) breathable air out of any given source of imbalance, giving more time for the ECLS systems to respond and correct that O2/CO2 imbalance. Having more time to react is generally a good thing in closed loop control systems. Every contribution to robustness adds up and after some point where every subsystem is made robust with relaxed tolerances you can have a habitat design that can be surprisingly safe. That would be the way to go, I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 01:08 pm
OK, so a big buffer of pressurized volume to dump excess heat into. I would guess just dumping into a more remote part of the glacier with water loops and heating the ice there a bit would be easier, but on the other hand you will be carving out bigger and bigger caves all the time anyway.

That's the idea. As I said this should be designed to get rid of excess heat without requiring any active technical devices. Plus the children can go outside and play. -15°C and dry air are ok without much wind. You could make snow, too. :)

There are glaciers big enough that you could build a whole 1 million people city that way and not use much of its volume. Though I believe this would be only one of different types of habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/14/2016 01:25 pm
Open pit mining techniques could be used to excavate large canals (100m+ deep). The pressurized "membrane" would be covered with 20m regolith from both sides.

The result could resemble Ceres station in Expanse.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2016 01:55 pm
Yea I loved the comment about the martians teaching us earth people how to take care of our resources. Just like in expanse!
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/14/2016 02:07 pm
Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

1.5g/cm^3 means 1.5t/m^3. So more like 6.67m thick for 10t. Mars gravity is only 0.38g, so more like 17.54m. Maybe it would make sense to reduce the pressure in the hab.

For a bigger habitat the excavated regolith for the cover will be smaller relative to the total excavated regolith. So I think bigger (or better deeper) is better. In theory.

Edit: Ups, corrected.

Yeah, I'm just using 1/3 g as Mars gravity for napkin engineering.

You can reduce hab-pressure slightly, but not by much. Or you will have to go up with the oxygen ratio, which comes with its own problems. There are good reasons for staying at Earth-like atmospheric pressure (like on the ISS).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 10/14/2016 02:50 pm
If you are trying to melt ice for its water, (and to make a habitat bigger) one advantage of an ice habitat is that any waste heat can be used for that very thing, melting ice in new areas. You just have to find a very efficient way of moving the heat to where you need it.

I'm not sold on this idea but I did want to point that out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/14/2016 03:38 pm
On one side is a rock wall sculpted with broad terraces and balconies connected to habitations extending a thousand feet up to the distant roof. It looks out into a space extending kilometers that is so vast it seems like an outdoor landscape. The floor is parkland that includes forrests and lakes. Towers as tall as 100 stories with broad balconies that offer landings for flying cars rise in the foreground. Some structures hover in mid air suspended from the roof. Architecture is fanciful and creative, liberated from earthly constraints of weather, geological instability and high gravity. Flying cars, safe because they're autonomous, are much more efficient than on earth. In the distance at night is a panorama of lights embedded in the ice face as an art project, seeming like an arc of starry night sky.

Unlike an O'Neill space colony, it grows organically in place, inhabited the entire time. It didn't have to be planned in every detail and completed before it was habitable. It's a more ordinary city in that respect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: b0objunior on 10/14/2016 03:48 pm
On one side is a rock wall sculpted with broad terraces and balconies connected to habitations extending a thousand feet up to the distant roof. It looks out into a space extending kilometers that is so vast it seems like an outdoor landscape. The floor is parkland that includes forrests and lakes. Towers as tall as 100 stories with broad balconies that offer landings for flying cars rise in the foreground. Some structures hover in mid air suspended from the roof. Architecture is fanciful and creative, liberated from earthly constraints of weather, geological instability and high gravity. Flying cars, safe because they're autonomous, are much more efficient than on earth. In the distance at night is a panorama of lights embedded in the ice face as an art project, seeming like an arc of starry night sky.

Unlike an O'Neill space colony, it grows organically in place, inhabited the entire time. It didn't have to be planned in every detail and completed before it was habitable. It's a more ordinary city in that respect.
The problem is that it has the same problems as cities on earth. Why go this far to the same mistakes. It has too have greater design for it to change.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 04:13 pm

You can reduce hab-pressure slightly, but not by much. Or you will have to go up with the oxygen ratio, which comes with its own problems. There are good reasons for staying at Earth-like atmospheric pressure (like on the ISS).

I am a great fan of 50% pressure. It is low enough that you can get into a spacesuit or low pressure habitat without waiting. It is low enough to make some building problems less severe. It is high enough that normal cooking is possible as the temperature of boiling water is ~80°C.

You may have to go slightly above 20% O2 but not too much.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2016 04:18 pm
3/4 atm is also very good. Basically what planes pressurize to. Also almost nobody can feel the difference at the equivalent 7000-8000 foot altitude. (if I got my numbers right)
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 04:18 pm
If you are trying to melt ice for its water, (and to make a habitat bigger) one advantage of an ice habitat is that any waste heat can be used for that very thing, melting ice in new areas. You just have to find a very efficient way of moving the heat to where you need it.

I'm not sold on this idea but I did want to point that out.

I am not sold on it too. It is not "the" solution for habitats. But it is one solution with the advantage to have large caverns. Something people will like. I do wonder how good ice will retain the air. But bubbles inside ice cores are used to determine the air components of long gone eras so it should be pretty impermeable.

One thing that is important IMO is the rule that habitats need to be stable both pressurized and unpressurized. Difficult but an important safety feature. Ice caves would have that feature.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 04:21 pm
3/4 atm is also very good. Basically what planes pressurize to. Also almost nobody can feel the difference at the equivalent 7000-8000 foot altitude. (if I got my numbers right)

If I got my info from diving right it would be slightly too high for getting into spacesuits without pressure adaption. Otherwise right, really no need to have full sea level pressure, every reduction helps. On the ISS full pressure has advantages in transfer from and to earth. Not an issue for Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/14/2016 04:51 pm
3/4 atm is also very good. Basically what planes pressurize to. Also almost nobody can feel the difference at the equivalent 7000-8000 foot altitude. (if I got my numbers right)

If I got my info from diving right it would be slightly too high for getting into spacesuits without pressure adaption. Otherwise right, really no need to have full sea level pressure, every reduction helps. On the ISS full pressure has advantages in transfer from and to earth. Not an issue for Mars.

Keeping O2 partial pressure equivalent to sea level at 1/2 atmosphere would be at 40% O2. Dropping O2 partial pressure to about 8000 foot (2400 meter) equivalent at 1/2 atmosphere would be 30% O2. That should work just fine for spacecraft or a Mars colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2016 09:31 pm

Keeping O2 partial pressure equivalent to sea level at 1/2 atmosphere would be at 40% O2. Dropping O2 partial pressure to about 8000 foot (2400 meter) equivalent at 1/2 atmosphere would be 30% O2. That should work just fine for spacecraft or a Mars colony.

Sounds good to me, if 40% partial pressure is really to high because of fire hazard. Some quarters like hospitals for some diseases may want to have higher oxygen partial pressure than 75% of sea level but for such areas special precautions against fire would be possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: drzerg on 10/14/2016 09:44 pm
with pressure you should consider long time health implications and pregnancy. people can live safe at 4000m on earth. so this pressure is not harmful regardless of O2 value.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/14/2016 10:07 pm
Some people can live at 4000m but it can cause severe problems for pregnancy. Basically unless the population is already genetically adapted to altitude there aren't going to be any babies.

Hypoxia, fetal growth and early origins of disease: the Andean curse on the Conquistadors (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2075320/)

Best keep pressure at sea level. There are enough unknowns with the low gravity and high radiation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2016 10:09 pm
I agree 4000m is a little extreme.
OTOH 3000m is much more doable. 10000 feet.
The grand canyon rim is about 9000 feet. Probably a little less.

EDIT:
I was way off 6800 feet for grand canyon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: obsever on 10/14/2016 10:49 pm
Best keep pressure at sea level. There are enough unknowns with the low gravity and high radiation.

The radiation problem can be hopefully solved with enough shielding. I'm afraid that the low gravity could turn out to be a show-stopper for pregnancy and child's growth. Perhaps a section of the habitat will be needed to rotate to provide artificial 1 g and children and pregnant women should spend most of their time there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/14/2016 11:10 pm
I agree 4000m is a little extreme.
OTOH 3000m is much more doable. 10000 feet.
The grand canyon rim is about 9000 feet. Probably a little less.

EDIT:
I was way off 6800 feet for grand canyon.

Here is a 2 km diameter dome, just off the vistor center of the grand canyon.
Are there similar steep hills in Vale Marineris or elsewhere?  Perhaps not the most practical solution  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/14/2016 11:26 pm
Not spectacular enough?

Bigdome2 with ITS!!

A pure tension structure, buildings inside are also seal-able in case the main dome fails; redundant protection.  Vegetation grows in the dome, but outside the buildings.
The overall structure is protected by a mini magnetosphere, similar, but more powerful, than those existing on the moon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/15/2016 12:21 am
90 percent of the glacier-cave talk here sounds like it's been lifted strait from the Zygote settlement of the Mars Trilogy.  The notion that a cave itself can be a pressure vessel is deeply flawed, the rock that a glacier sits on can easily be fractured and allow air to escape, as the habitat air is warm it can cause sub-surface melting, likewise the interior air in the cave would have to be kept away from the ice roof to prevent all the issues I described earlier. 

The net effect is that your going to need to have a full top and bottom pressure envelope inside the cave, it can be thin because it dose not need protection from micrometeorites as it would exposed on the surface but the cave is really not doing anything that a architectural dome and a few meters of regolith couldn't do, and it has disadvantages too, susceptibility to creep over time, difficulty in dumping waste heat as have been mentioned, inability to use skylights or any other top-down access to the habitat area.  Probably most important is that it requires that you not perform simple surface mining of the same glacier body that your living in so as to avoid damaging your own habitat.

Construction on the surface with arches, vaults, columns and other compression load bearing structures can provide the necessary radiation protection without any of these issues.  The same thin membrane pressure vessels inflated inside these protected spaces will be necessary but this is unavoidable and a wash.  Also note that some posters have erroneously claimed that a single massive pressure vessels is more efficient then many small ones, this is a common error in thinking that the pressure vessel mass scales only with surface area, in actuality it scales with volume due to a large vessel needing a thicker wall.  Given the inherent danger, I would say death-trap-ishness, in a single pressure vessel the interconnecting of many individual pressure vessels is certainly the way to go.

Note that a livable habitat is going to consist of a LOT more mass in equipment, life-support and otherwise beyond the pressure vessel, even a pressure vessel made 100 percent from local materials will need nearly the same amount of vital equipment to shipped in.  This is the flaw in most space-cadet style housing solutions, they pretend that they are making log cabins in which just walls and roof are all that's needed and that they are saving 90 percent of the shipment mass from Earth.

I think you're confusing pressure vessels with making things gas-tight. "Arches, vaults, columns and other compression load bearing structures" won't help at all because your building will not be under compression at all. It will be under tension. The atmospheric pressure inside will try to push things apart form the inside.

Also a few feet of regolith on top won't help much against an atmospheric pressure of 10 tons per square meter trying to push things apart from the inside.  You'd need to pile 10 tons of regolith per square meter on top of your building to counter the atmospheric pressure inside. Regolith has a density of about 1.5 g/cm^3, so in Mars' gravity this would be a layer of 20 meters (about 65 feet) thick. Only if you would add even more on top your structure will start to come into compression and you'll start to need arches, columns etc. Until then it is under tension and will try hard to explode from the inside.

Cracks in rock in a cave or tunnel aren't a problem, a thin membrane to prevent gas from escaping is easy, but there is no such thing like a "thin membrane pressure vessel". In a cave the pressure would be countered by the weight of the rock above and around it. If you don't have that weight you have to counter the pressure by tension in your pressure vessel and this not going to be a thin membrane then or bricks, or anything short of steel or aluminum, or massive reinforced concrete.

And yes, you need more than just pressure vessels to live in, but they're the biggest things you need and if they fail you won't have any time to fix things, because you will be dead immediately. They are the first and most crucial thing you need. And if you want to live and grow food in them, they need to be big and you need many of them and they need to be safe.

I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:08 am
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/15/2016 01:32 am
A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material ...

As your average party balloon, which can sustain a pressure differential of >1 atm, demonstrates. (Of course, you'll want to use a material that doesn't 'pop' when punctured!)

Quote
In my scenario the arcade structure provides all [the abrasion resistance and ballistic protection] allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

You could just inflate it inside a cave, or lava tube or even a constructed tunnel. This helps provide radiation protection, as well. On the surface, you could just shovel regolith over it (possibly in sandbags, to prevent abrasion), but a 1 atm differential would easily sustain the weight of the few meters required.

Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/15/2016 01:38 am
Regarding "flat plains" and building regolith-covered habitats.
Last time I checked, even Mars plains are not that flat. They have these nifty depressions called "craters", of all sizes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:43 am
Let's design my 2 km dome:

For a thin walled sphere, s=P*r/2t
s= strain
P= Pressure
r= radius
t= thickness

Supposing we use high strength steel, and a thickness of 0,5m I find that the dome needs to be made from 20% steel; the rest can be plexiglass panes set in the structure.  Safety factor of 3.
The mass is 10 million tonnes, plus the plastic and the ground anchors. If we stuff 1million persons in there, it's 10 tonnes of steel per person.
Seems heavy.

Interestingly, if we design smaller domes, let's say 200m in diameter, the mass ratio goes down linearly with the floor area. So instead of 10 tonnes per person, it's 2 tonnes per person.
So 100 x 200m domes have the same floor area as a single 2000m dome, but 10% of the mass.

So the people saying bigger is better may be wrong, in this case.  We should plan for 100 small domes not for a single large one.

Seems a lot safer, as well.

Spreadsheet is joined.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:55 am
A bit closer. :)

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/15/2016 02:36 am
A few related ideas:
I think mars colonies are likely to grow in a fashion resembling plants.

The "Leaves" are the solar panels and perhaps low pressure greenhouses or pipes carrying algae to exploit photosynthesis. In any case it will gather solar energy and like leaves I expect this portion to be somewhat fragile and not too hard to replace/repair.

Below ground you have "roots" being mining tunnels that are later buttressed to become living areas and storage areas.. which are a bit like a plant's tubers if you like. These roots would also form new shoots to the surface like some plant types.

One of the main forms of ISRU will be organic chemistry, combining CO2 and N from the air and ice from the soil along with some other elements. There are so many useful materials you can make from this small easily accessible group of CHON elements that are also the key elements that plants (and all life) exploits. I think there will be constant economic pressure to do as much as we can with these ingredients and, as much as practical, minimise requirements on things like rare earth metals that might have to rely on distant mines.

Im sure this plant analogy would have heaps of exceptions but it is easy to see why a mars city has reasons to move somewhat further in this direction than an earth city.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/15/2016 02:52 am
I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

Not sure why you want to build an arcade structure when the pressurized hab provides structural support for free. Just cover the hab with regolith, I don't see a problem with that. In theory this would work with an air-tight membrane which is increasingly pressurized while being covered with regolith, but you probably want it to have significant tensile strength as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/15/2016 03:08 am
O2 partial pressure equivalent to sea level at 1/2 atmosphere would be at 40% O2. Dropping O2 partial pressure to about 8000 foot (2400 meter) equivalent at 1/2 atmosphere would be 30% O2. That should work just fine for spacecraft or a Mars colony.

I've seen 1/2 atmosphere before, e.g. here:

(http://settlement.arc.nasa.gov/75SummerStudy/table4.3.gif)

http://settlement.arc.nasa.gov/75SummerStudy/Chapt4.html#Life
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/15/2016 03:21 am
Im also fairly enthusiastic about some general ideas mentioned here:
Containing water under an oil layer on Mars (http://forum.nasaspaceflight.com/index.php?topic=40628.msg1555177#msg1555177)

The key points I think are important:
*There are apparently vast bodies of ice on mars, even near the equator, under say ten meters of regolith.
*It is possible to liquify large amounts of this water "for free" using waste heat. This might even happen inadvertently.
*Large bodies of water for free are potentially very useful, but you would also be making your previously solid ground very unstable. The regolith would want to collapse and fall through the lighter water.
*The solution could be to let the regolith cover fall through and replace it with a layer that is lighter than water.

 This does not need to be an "oil". It could be anything from plastic bubbles to rafts to traditional engineering. The point is just that your roof material is less dense than your water and you can extend your roof incrementally, unlike some sort of loadbearing arch you have to keep redesigning as the ground softens more and more beneath it.

In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 10/15/2016 03:40 am
I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

Not sure why you want to build an arcade structure when the pressurized hab provides structural support for free. Just cover the hab with regolith, I don't see a problem with that. In theory this would work with an air-tight membrane which is increasingly pressurized while being covered with regolith, but you probably want it to have significant tensile strength as well.

So what happens to your regolith-covered balloon when something goes wrong and lets the pressure out with regolith still on top?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/15/2016 03:55 am
So what happens to your regolith-covered balloon when something goes wrong and lets the pressure out with regolith still on top?

You won't have to organize a burial for the suffocated colonists.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 10/15/2016 03:58 am
 I suppose there's a silver lining of some sort to be found in nearly everything.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/15/2016 07:40 am
I'm sorry but you have completely misunderstood me.  The pressure vessels is not going to be relying on any of the structural arches and vaults over it to retain pressure, it is just a freestanding bubble under the protection of another structure with ambient air pressure gap between them.  I know lots of space-cadets fantasize about using regolith mass to contain air-pressure but that is a crazy idea and I don't subscribe to it.

A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material, Bigelow inflatables and space suits work on the same principle, a tensile restraining layer and a rubberized airtight layer inside that.  But 90 percent of the mass is in abrasion resistance and ballistic protection layers outside of that.  In my scenario the arcade structure provides all that protection allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

Not sure why you want to build an arcade structure when the pressurized hab provides structural support for free. Just cover the hab with regolith, I don't see a problem with that. In theory this would work with an air-tight membrane which is increasingly pressurized while being covered with regolith, but you probably want it to have significant tensile strength as well.

Regolith in direct contact with a membrane type pressure vessel would be abrasive to it for one, necessitating more layers for protection.  The regolith would also be extremely cold which would cool both the membrane material and the interior habitat, the cooled membrane could lose strength and the cooling of the interior is undesirable for condensation reasons.  It's preferable to have maximum insulation around the habitat and to expel heat only via a radiator so you can have full control over the temperature inside.  Having a small ambient air, aka near vacuum, gap between the membrane and any solid object is virtually the best insulation you can have.  This applies to the ground too so I would put foam on the ground and then place the inflatable habitat onto that.

The direct regolith covering of an inflatable habitat is a good strategy for very early habitats, using essentially full Bigelow type habitats with their extensive layers and insulation would allow direct burial.  The construction I was describing was intended for mid to late phase settlement in which more local materials are used.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 08:45 am

So what happens to your regolith-covered balloon when something goes wrong and lets the pressure out with regolith still on top?

That's why I keep arguing that any structure designed needs to be stable both on ambient pressure and pressurized. It does not make construction easier but it is doable. Neglect that requirement on peril of your life.

Edit: Impalers suggestion to build domes for radiation protection and inflate structures inside is one of the possible solutions. Not necessarily the best but one feasible solution
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 08:50 am
I've seen 1/2 atmosphere before,

Some argue that the higher relative oxygen like 40% at 50% sea level pressure to maintain the same oxygen partial pressure increases the fire hazard. I am not sure this is true or critical but I don't want to flatout reject the argument as I don't know.

The argument is while initiating a fire may not be more likely, the fire would burn much hotter and faster for lack of an inert component damping it. I would love to know at which level it becomes critical.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/15/2016 09:02 am
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon

Radiation protection is only one reason why you might want to excavate a habitat on a cliffside. Remember that the probability of a disaster is one minus the product of all probabilities of every critical thing working out as planned, over time. A robust design meant to last for decades will rely on fewer critical things and will have higher probabilities of success for each.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 11:07 am
Mars has no global magnetic field. But I have heard it has localized magnetic fields. I would like to see research on these. Do they locally reduce radiation?

If yes it would be good to put settlements there. Not having to plan for heavy radiation shielding would make many things easier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 01:43 pm
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon

Radiation protection is only one reason why you might want to excavate a habitat on a cliffside. Remember that the probability of a disaster is one minus the product of all probabilities of every critical thing working out as planned, over time. A robust design meant to last for decades will rely on fewer critical things and will have higher probabilities of success for each.
Some disasters are relative.  When, not if, a mini magnetosphere generator fails, if it can be repaired in such a time that inhabitants do not get too much radiation dosage ( a few months imho) then it's just an event.
It will be possible to have two mini magnetosphere generators, then the issue is only can you switch from one to the other without problems. 
So yes, it would be interesting to see if these can function on Mars, or if the atmosphere, thin as it is, makes the idea fail in some way.
There are papers on the lunar mini magnetospheres, they pop out on google easily.  There is a british group investigating them for space vehicle protection.  I believe the american version of the idea failed, somehow.

The solution that will win out is the one that requires less energy overall.  Domes inside a lava tube seems  interesting, as you separate the pressure requirement from the radiation protection requirement, and you don't have the abrasion problems.  Lava tubes are obviously stable, over millions of years, structurally. The chemical environment inside lava tubes is unknown though, so exploration is a basic requirement.  And lighting the lava tube in non trivial, compared to using natural light. Basically requires 1m2 of solar panel for each m2 of lit area, more or less?
As are experiments in reduced gravity at 1/3 and 1/6th.  It's a crying shame NASA or some other group hasn't been doing this for decades, but let's hope that will be changing in the next few years.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/15/2016 02:05 pm
Is there a thread somewhere on the site where they managed to prove or disprove the idea of using a mini magnetosphere for radiation protection?

Because if they are possible, the justification for buried habitats pretty much goes away.  And we can profit from the 1/3g to create amusing structures.

From national geographic : Mini Magnetic Shield Found on the Moon

Radiation protection is only one reason why you might want to excavate a habitat on a cliffside. Remember that the probability of a disaster is one minus the product of all probabilities of every critical thing working out as planned, over time. A robust design meant to last for decades will rely on fewer critical things and will have higher probabilities of success for each.
Some disasters are relative.  When, not if, a mini magnetosphere generator fails, if it can be repaired in such a time that inhabitants do not get too much radiation dosage ( a few months imho) then it's just an event.
(...)

I agree that disasters are relative and that one would have time to fix the machines that create the magnetosphere. A magnetosphere won't increase disaster risk if the labor/capital/energy resources devoted to the maintenance and repairs of the magnetosphere don't compete with opportunities to increase the safety margins for other critical systems (air, water, greenhouses etc.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 02:28 pm
One fundamental problem with domes on Mars is anchoring it them the ground. It might be best to simply continue the membrane construction all around the habitat, i.e, build floors as well for every habitat, rather than try to anchor the dome to the ground.  With a floor, all forces are kept in the tension structure.

If you do use anchors, a quick calculation suggest that the bottom of the dome should be dug-in for quite a few meters and then some kind of massive footing used.  This could be covered with regolith to create sufficient inertial mass to keep the dome down.  150 times the mass of the dome for a 200m dome, 13 x the mass of the dome for a large 2000m dome.

Updated spreadsheet.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 02:37 pm

The solution that will win out is the one that requires less energy overall.  Domes inside a lava tube seems  interesting, as you separate the pressure requirement from the radiation protection requirement, and you don't have the abrasion problems.  Lava tubes are obviously stable, over millions of years, structurally. The chemical environment inside lava tubes is unknown though, so exploration is a basic requirement. 

Exploration is a basic requirement. Yes, even if they are supposed to be long time stable, the holes seen and even have been seen appearing suggest they are not infinitely stable and I would want a very thorough geological survey before I feel safe in them. Also living in a black hole is not an attractive proposition. As you mentioned maybe a lot of lighting even of unused areas may be needed for humans to feel comfortable.

And lighting the lava tube in non trivial, compared to using natural light. Basically requires 1m2 of solar panel for each m2 of lit area, more or less?
As are experiments in reduced gravity at 1/3 and 1/6th.  It's a crying shame NASA or some other group hasn't been doing this for decades, but let's hope that will be changing in the next few years.

Depends on what the lighting is for. Enough for the huaman eye to see needs very little light. 1/1000 of full light will serve quite well. If you want to grow plants, even shadow suited plants like ferns and philodendron you may need 10% of full sunlight on earth.

If you want to do farming a lot of light is needed. I prefer surface habs with natural light for that reason, maybe augmented with mirrors or artificial lighting in some growth phases.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2016 03:40 pm

If you want to do farming a lot of light is needed. I prefer surface habs with natural light for that reason, maybe augmented with mirrors or artificial lighting in some growth phases.

My current favorite is surface habs made from tensile domes, 90% transparency, with a minimagnetosphere radiation protection system.  That sentence contains a fair amount of science fiction at this time, unfortunately  ;-).

Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/15/2016 04:20 pm
I've seen 1/2 atmosphere before,

Some argue that the higher relative oxygen like 40% at 50% sea level pressure to maintain the same oxygen partial pressure increases the fire hazard. I am not sure this is true or critical but I don't want to flatout reject the argument as I don't know.

The argument is while initiating a fire may not be more likely, the fire would burn much hotter and faster for lack of an inert component damping it. I would love to know at which level it becomes critical.

O2 partial pressure can be set at 2400 meters instead of sea level. That's about 75% of sea level. It is also just below the altitude where healthy unacclimated individuals suffer from altitude sickness. That level of O2 partial pressure works well on aircraft. It should reduce the fire risk in the proposed 1/2 atmosphere.

While it's well know that a high O2 level increases fire risks, I haven't be able to find actual numbers to determine an acceptable O2 level.

In relation to Mars habitats, just in case the original point has been lost, 1/2 sea level atmospheric pressure means pressurized structures don't have to as strong. Less material needed, cheaper, and more options for architectural creativity.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/15/2016 04:25 pm

If you want to do farming a lot of light is needed. I prefer surface habs with natural light for that reason, maybe augmented with mirrors or artificial lighting in some growth phases.

My current favorite is surface habs made from tensile domes, 90% transparency, with a minimagnetosphere radiation protection system.  That sentence contains a fair amount of science fiction at this time, unfortunately  ;-).

Underground vs surface is probably a combination of aesthetic preference and other assumptions. I kinda prefer large underground spaces even if there are good surface solutions to radiation, think nuclear reactors are necessary and don't expect agriculture to use natural sunlight or soil. The Martian population if it's large will probably have a variety of preferences and try different living modes.

The living in the space hollowed out of glaciers notion has the appeal of having an "amazing" long term city vision but being practical to start on even in early missions, because the ice is going to be consumed anyway and a volume created inside the glacier whether you use it or not. It only works if the settlement is in that location and surface habitats would work in many locations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 08:10 pm
I did a little calculation on how much volume of ice would be dug out for ITS fuel.

Initially Elon Musk said 10 cargo flights to 1 passenger flights. I am aware it was a very rough estimate, nothing calculated as it cannot be calculated yet. As the cargo capacity is so much bigger now I go with 3 cargo to 1 passenger flight.

If I did not miscalculate 1 flight needs 580t of water. Multiplied by four and calculating that ice is less dense I get ~2500m³ of excavated volume. Make that 3000m³ of volume per passenger ship, because some water per settler is also needed. Assuming that a large part of that volume would be open space it is not  enough to give a decent living space for all. But it could provide a good part of the needed living space and would give open spaces to go to and not be confined to closed habitats all the time.

I start to warm up to ice, hadn't considered it before.

The concept would avoid some of the problems of other suggestions. Digging into the ice and occupy all the volume with habitats would make them vulnerable to moving of the ice, much less critical with open spaces around the habitats. Insulation and thermal management would also be easier. Disadvantage is that the volume is not enough for all settlers. But that may not be a disadvantage really. Different types of habitats will be good to have.

It would require quite significant thickness of ice to maintain a cover above the caverns that is safe from caving in. Also thick enough to contain the pressure inside the habitats. I don't want to calculate it. Regolith cover will help in containing pressure, but the ice has to hold the regolith while not yet pressurized too. I leave that to the civil engineers and geologists.

Industrial construction and agriculture would mostly be elsewhere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/15/2016 09:09 pm
I did a little calculation on how much volume of ice would be dug out for ITS fuel.

Initially Elon Musk said 10 cargo flights to 1 passenger flights. I am aware it was a very rough estimate, nothing calculated as it cannot be calculated yet. As the cargo capacity is so much bigger now I go with 3 cargo to 1 passenger flight.

If I did not miscalculate 1 flight needs 580t of water. Multiplied by four and calculating that ice is less dense I get ~2500m³ of excavated volume. Make that 3000m³ of volume per passenger ship, because some water per settler is also needed. Assuming that a large part of that volume would be open space it is not  enough to give a decent living space for all. But it could provide a good part of the needed living space and would give open spaces to go to and not be confined to closed habitats all the time.

I start to warm up to ice, hadn't considered it before.

The concept would avoid some of the problems of other suggestions. Digging into the ice and occupy all the volume with habitats would make them vulnerable to moving of the ice, much less critical with open spaces around the habitats. Insulation and thermal management would also be easier. Disadvantage is that the volume is not enough for all settlers. But that may not be a disadvantage really. Different types of habitats will be good to have.

It would require quite significant thickness of ice to maintain a cover above the caverns that is safe from caving in. Also thick enough to contain the pressure inside the habitats. I don't want to calculate it. Regolith cover will help in containing pressure, but the ice has to hold the regolith while not yet pressurized too. I leave that to the civil engineers and geologists.

Industrial construction and agriculture would mostly be elsewhere.

So in an era when there are 1000 ships per synod, they would consume 3 million cubic meters of ice, or about a slice of glacier 300m deep x 1000 m X 10m thick. They could do that for 100 synods or over 213 years before consuming a square km of a single 300m deep Glacier.

Rereading I forgot you were doing it with 4 shiploads total per passenger ship so it's only a quarter of that to match, either way it's the same order of magnitude.

It's a good illustration of the magnitude of the water resource there.


Of course they could also melt as much of the  glacier as they had spare heat for and keep it as lakes or reservoirs of water ready to pump too.

Even if agriculture is vertical and in underground spaces like that, it still makes some sense to do in in separate cells. One advantage ag has in completely controlled environments is no pests or diseases, no need for pesticides. Keeping units separate from each other and people helps prevent contamination and dealing with it if it happens.

About the roof, I was thinking of that as an engineered structure maybe some form reinforced Pyekrete https://en.m.wikipedia.org/wiki/Pykrete (https://en.m.wikipedia.org/wiki/Pykrete). While sawdust isn't an option maybe atmospheric carbon can be made into some sort of sprayable carbon fiber/nanotube stuff. In a Mars environment this stuff could be as permanent as concrete and more easily made self repairing. The air pressure at a full atmosphere vs almost a vacuum in Mars gravity would support a lot but it would be best to have a very robust roof that supports itself even with pressure loss. Marscrete using melted sulfur was intended for extreme water shortages. This is the opposite extreme with plenty of water that with appropriate care is easy to keep frozen in that environment.

Pyekrete would be a superior material to plain ice for any structure when water is plentiful. The problem on Mars is a good substitute for sawdust.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/15/2016 10:19 pm
About the roof, I was thinking of that as an engineered structure maybe some form reinforced Pyekrete https://en.m.wikipedia.org/wiki/Pykrete (https://en.m.wikipedia.org/wiki/Pykrete). While sawdust isn't an option maybe atmospheric carbon can be made into some sort of sprayable carbon fiber/nanotube stuff. In a Mars environment this stuff could be as permanent as concrete and more easily made self repairing. The air pressure at a full atmosphere vs almost a vacuum in Mars gravity would support a lot but it would be best to have a very robust roof that supports itself even with pressure loss. Marscrete using melted sulfur was intended for extreme water shortages. This is the opposite extreme with plenty of water that with appropriate care is easy to keep frozen in that environment.

Pyekrete would be a superior material to plain ice for any structure when water is plentiful. The problem on Mars is a good substitute for sawdust.

If you have enough ice and I assume they will build the first settlement at a location that has, the easiest way to have a stable roof is going 30m deep for the roof of the caverns and make the roof  a dome. Then there would be no need for any reenforcement. It does require at least an ice sheet of 40m thickness, more is better.

As I mentioned, I have adjusted the ratio cargo to passenger for the higher payload of 300t instead of 100t. It is somewhat arbitrary but I need some estmate for calculation.

Title: Re: Envisioning Amazing Martian Habitats
Post by: UberNobody on 10/16/2016 12:19 am
Here is what I've been thinking about ever since Elon started talking about 100t (now 300t!) to the surface of Mars along with ISRU production before the first human mission.

My big assumption is that water extraction for ISRU will be done with an automated open-pit mining operation.  Such an operation could easily be adapted to build habitats.

Because you are already running tons of material through an oven to extract water, it is relatively straightforward to add-on a sulfur extraction oven as well as a series of grates to filter out fine particles of regolith.  You can extract other materials as well, but I'll stick with sulfur and fine regolith for now.  They make a pretty good option for mars-crete: https://www.technologyreview.com/s/545216/materials-scientists-make-martian-concrete/

Now that you have the materials for mars-crete, a huge pit in the ground, and a lot of loose regolith sitting around, you can 3D print some pretty large structures in that pit.  Afterwords you would cover the whole thing with loose regolith, apply a liner to the inside (perhaps sprayed on), and pressurize it.

These structures could eventually be mall-sized.  Locally produced rebar would allow for some pretty epic domes and arches to be constructed that still hold up when not pressurized.  Simulate a sky on the ceiling and it could be quite comfortable to spend time in. 

Above-ground structures are cool, and we definitely need some, but underground/covered structures have a lot of advantages, especially if you already have mining operations going on for ISRU.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Impaler on 10/16/2016 12:24 am
I've seen 1/2 atmosphere before,

Some argue that the higher relative oxygen like 40% at 50% sea level pressure to maintain the same oxygen partial pressure increases the fire hazard. I am not sure this is true or critical but I don't want to flatout reject the argument as I don't know.

The argument is while initiating a fire may not be more likely, the fire would burn much hotter and faster for lack of an inert component damping it. I would love to know at which level it becomes critical.

I've shown you this research before, http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070005041.pdf

https://en.wikipedia.org/wiki/Limiting_oxygen_concentration#cite_note-6

Oxygen percentage is the dominant factor, not partial pressure though their are MINOR effects from pressure.  Inert gasses not only quench and slow combustion, if they are high enough they can prevent ignition in the first place.

Lungs operate on partial pressure because they are basically gas to liquid diffusion devices that seek to balance gas pressure.  Fire is an exponential chemical chain reaction which is why we can describe a fuels ideal mixture ratio with air or oxygen that becomes combustible, below critical ratios the chain reaction can not sustain itself due to the deadening effect of the inert materials, this is very much analogous to criticality in a nuclear chain reaction.

The two processes have nothing to do with each other and people who have a little bit of understanding about lungs have been trying to slap that model onto fire without understanding the difference, classic 'reasoning by analogy' and it's been repeated sooooo many times on these forums that many people believe it, partly because they want too.

On ISS the maximum oxygen concentration for normal operations is 24 percent in most of the structure and 30 percent in the airlock.  The partial pressure of oxygen is maintained between 2.8 and 3.4 psi.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sdsds on 10/16/2016 12:42 am
Do we know ... um ... anything at all about combustion in Mars gravity? The microgravity combustion experiments (Saffire) at least seem to indicate gravity might be a factor in what atmospheric conditions would pose a fire risk.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Optimist on 10/16/2016 01:57 am
For those interested, the idea of tunneling into a glacier, and making chambers for a startup colony, was discussed some in this thread, about a year ago.

http://forum.nasaspaceflight.com/index.php?topic=34667.880



Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/16/2016 10:01 am
Great picture UberNobody... is it from Italy? Have people come across vaguely similar architectures in other cultures? One is the covered bazaar in Istanbul which is several centuries old. I do believe that on Mars, it will be important to recreate and mix cultural architecture from everywhere on Earth. Not to perpetuate ethnic differences but to celebrate the diversity of our civilizations as a new civilization is born. Think of USA and other Western nations celebrating ancient Greco-Roman culture through the architecture of important buildings; I think Mars should celebrate the diversity of our architectural treasures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 02:26 pm
Maybe when we have sealed and pressurized huge lava tubes. Util then it will be form follows function. There will be strict requirements forcing the design.

Though Elon Musk seems to have a personal dispense from these rules. Look at Crew Dragon and ITS. They both look like from an italian designer for the next great space opera movie. Absolutely gorgeous.
Title: Re: Envisioning Amazing Martian Habitats
Post by: launchwatcher on 10/16/2016 04:19 pm
Great picture UberNobody... is it from Italy?
It's the Galleria Vittorio Emanuele II (https://en.wikipedia.org/wiki/Galleria_Vittorio_Emanuele_II) in Milan.   One of the world's oldest enclosed shopping malls.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 10/16/2016 05:09 pm
About the roof, I was thinking of that as an engineered structure maybe some form reinforced Pyekrete https://en.m.wikipedia.org/wiki/Pykrete (https://en.m.wikipedia.org/wiki/Pykrete). While sawdust isn't an option maybe atmospheric carbon can be made into some sort of sprayable carbon fiber/nanotube stuff. In a Mars environment this stuff could be as permanent as concrete and more easily made self repairing. The air pressure at a full atmosphere vs almost a vacuum in Mars gravity would support a lot but it would be best to have a very robust roof that supports itself even with pressure loss. Marscrete using melted sulfur was intended for extreme water shortages. This is the opposite extreme with plenty of water that with appropriate care is easy to keep frozen in that environment.

Pyekrete would be a superior material to plain ice for any structure when water is plentiful. The problem on Mars is a good substitute for sawdust.

If you have enough ice and I assume they will build the first settlement at a location that has, the easiest way to have a stable roof is going 30m deep for the roof of the caverns and make the roof  a dome. Then there would be no need for any reenforcement. It does require at least an ice sheet of 40m thickness, more is better.

As I mentioned, I have adjusted the ratio cargo to passenger for the higher payload of 300t instead of 100t. It is somewhat arbitrary but I need some estmate for calculation.

You don't know the nature of the material on top of the glacier. It might be quite loose and completely ineffective for this purpose. If you're going to rely on it, especially for a growing volume, the roof has to be engineered. The roof is the only part of a vast habitable volume that has to be built and it can use materials in place (or nearby for water) for most of it's mass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 10/16/2016 05:32 pm
I would think something like the LowLine in New York City would be more functional and practical in the long run.
http://thelowline.org/about/project/
good rendering http://thelowline.org/wp-content/uploads/2016/06/park-plans-lowline-lab-web.jpg
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 05:58 pm

You don't know the nature of the material on top of the glacier. It might be quite loose and completely ineffective for this purpose. If you're going to rely on it, especially for a growing volume, the roof has to be engineered. The roof is the only part of a vast habitable volume that has to be built and it can use materials in place (or nearby for water) for most of it's mass.

Loose regolith would be my strong expectation. Yes, it would not contribute to bearing the load. That's why I said a sufficiently large ice cover is necessary.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/16/2016 07:52 pm
A pressure envelope can be made of a thin membrane so long as it's a high tensile strength material ...

As your average party balloon, which can sustain a pressure differential of >1 atm, demonstrates. (Of course, you'll want to use a material that doesn't 'pop' when punctured!)

Quote
In my scenario the arcade structure provides all [the abrasion resistance and ballistic protection] allowing the actual pressure vessel to be much lighter, it is taken into the arcade and simply inflated and interconnected with other similar pressure vessels, the volume can be very large on the order of an apartment buildings each.

You could just inflate it inside a cave, or lava tube or even a constructed tunnel. This helps provide radiation protection, as well. On the surface, you could just shovel regolith over it (possibly in sandbags, to prevent abrasion), but a 1 atm differential would easily sustain the weight of the few meters required.

A party balloon can sustain only a very small pressure differential, maybe 0.01 to 0.05 atmospheres. Also keep in mind that the strain on the skin and with it the needed tensile strength of the used material rises with the radius of the pressure vessel, even if the pressure stays the same. Pressure vessels scale very badly. Increase the size of your vessel tenfold and the walls have to be ten times as thick. It's unfortunate, but that's how it is. That's the reason that the typical SF trope of cities under big transparent domes is more fiction than science.

But yes, of course you can use a thin membrane for your building-sized pressure vessel as long as it is made from very high tensile strength material. This is as true as saying that you can travel to Mars in a few days if you have engines with a very high ISP. Hey, why not make it radiation-tight and transparent at the same time? Unobtainium can do everything, right?


One of the big advantages of Mars over open space or asteroids is that it has not only lots of inert mass laying around but also gravity. Because mass and gravity gives weight and weight gives pressure basically for free. It's an in situ resource just as water in the ground and CO2 in the atmosphere is an in situ resource.

So I think the first engineering crews on Mars will live in their ships and in pressurized rovers, maybe they will have a small pressurized hab delivered in one piece from Earth. But the first long-term crews will already live underground either in caves down in the ice or later in tunnels and caves drilled in rock.

Food will be grown either in many small pressure vessels (small because small is much easier and needs much less mass for the same sum of volume) or in artificially lighted caves. Because even at the low efficiency of solar panels and LED lights solar panels can be made very light (much lighter than pressure vessels) and 10 square meters of solar panels are lighter and easier to transport than one square meter of pressure vessel. Or use a nuclear reactor. It also means you can have large open spaces with plants underground and this is much better for colonists than living in cramped vessels while growing food in small containers with glass roofs they can't enter. This would be an expensive prison, not a colony.

Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

This gives lots of room with radiation shielding and most of it could be done automatically by machines since drilling down is as straight-forward as can be. Once pressurized you can expand them with horizontal parts even while already living there. And when deep enough you get a nice pressure gradient which makes sealing the roof easier, since the pressure at the top is less than on the bottom ;-)

Huge open spaces also give much more buffer room for controlling your atmosphere (oxygen, CO2, trace gases) and fixing leaks, while in small pressure vessels you have to tightly control everything and a leak is an immediate emergency (if your pressure vessel doesn't fail catastrophically by bursting anyway, pressure vessels that are not perfectly build are prone to do that). In a vertical space you can also exploit the fact that warm air rises and cold air falls to get some mixing instead of having to duct the air around with lots of fans. Which would be noisy (the ISS it notoriously noisy). If you have ever been in a cave or a mine you'll also know that these are much quieter than metal vessels. Living in a machine-filled pressure vessel is a lot like living in a server room.

And again: This planet has lots and lots of rock. It's free and already pressurized by the weight above it. Use it. You just have to dig some out to make room. OK, it won't be really easy, but for a million people it should scale much better than any kind of pressure vessels you have to build.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/16/2016 07:54 pm
One detail to the use of an ice cavern is that it will need to be pressurised, otherwise the ice will sublimate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/16/2016 08:12 pm

You don't know the nature of the material on top of the glacier. It might be quite loose and completely ineffective for this purpose. If you're going to rely on it, especially for a growing volume, the roof has to be engineered. The roof is the only part of a vast habitable volume that has to be built and it can use materials in place (or nearby for water) for most of it's mass.

Loose regolith would be my strong expectation. Yes, it would not contribute to bearing the load. That's why I said a sufficiently large ice cover is necessary.


NASA has found several cases of small fresh impact craters that exposed ice under a shallow cover and the Phoenix lander seems to have exposed ice by the thrust of its landing engines under a very shallow cover:

http://www.space.com/5435-images-phoenix-lander-show-martian-ice.html

I think it may be that the regolith on top is just thick enough to protect the ice from sublimating. We don't really know how all this ice came to be where it is, but there seems to be a lot of it. Maybe the ice is mixed with a certain amount of dust and the sublimating ice then left the dust behind until the dust layer was thick enough to prevent further sublimation.

The dust/regolith won't serve any purpose for us here. If you have deep ice just drilling down 30 meters or more and then melting out caves there and pump up the water would be the easiest way to handle it. Open pit mining would be idiotic because you expose the ice for sublimation then. Even if there is quite a lot of dust mixed in with the ice melting the ice would just leave a layer of stuff on the bottom of your cave.

MRO seems to have found very thick (up to half a mile) quite pure water ice though with its radar in a few places.

We need to research this better though. And go for some ground truth. A precision landed Red Dragon with a drill would be very useful... And a Martian GPS of course. We need to plot all of this very precisely.

Lots of work ahead!
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/16/2016 09:20 pm
Let's design my 2 km dome:

For a thin walled sphere, s=P*r/2t
s= strain
P= Pressure
r= radius
t= thickness

Supposing we use high strength steel, and a thickness of 0,5m I find that the dome needs to be made from 20% steel; the rest can be plexiglass panes set in the structure.  Safety factor of 3.
The mass is 10 million tonnes, plus the plastic and the ground anchors. If we stuff 1million persons in there, it's 10 tonnes of steel per person.
Seems heavy.

Interestingly, if we design smaller domes, let's say 200m in diameter, the mass ratio goes down linearly with the floor area. So instead of 10 tonnes per person, it's 2 tonnes per person.
So 100 x 200m domes have the same floor area as a single 2000m dome, but 10% of the mass.

So the people saying bigger is better may be wrong, in this case.  We should plan for 100 small domes not for a single large one.

Seems a lot safer, as well.

Spreadsheet is joined.

Thanks for putting some numbers to what is a lot of handwaving otherwise.

Hmm. 1km radius makes 3.14km^2 ground. With 1 million people this gives a population density of 318000 people per square km. This is about the density of the most densely populated urban areas in Hong Kong (which is quite the record on Earth). You'd have to fill the thing with skyscrapers.

And then you need all the machinery and of course you need to grow food. Actually you'd need to have a much smaller population density, so build more domes. And rebuild them regularly, since these things will not be long-term stable (the steel will rust, the plexiglas windows will get brittle and one day it will fail and all will die. They will die early anyway with all the unshielded radiation). Ten million tons of steel is too valuable for just a few decades.

I think getting your habitats stable for a long time is important, you'll have more than enough work even without rebuilding your habitats every few decades. I would trust a few hundred meters of rock over my head better than that and replacing/improving/expanding other things can be done incrementally then. On a geologically dead planet as Mars is the crust should be stable over a really long time (millions of years at least). Domes certainly aren't.





Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 11:20 pm
One detail to the use of an ice cavern is that it will need to be pressurised, otherwise the ice will sublimate.

Not really a point of much concern. Ice can only sublimate when enough energy is added. With no sun the atmosphere would not provide much energy for sublimation. Even on the surface providing shade would greatly reduce the rate of sublimation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/16/2016 11:29 pm


NASA has found several cases of small fresh impact craters that exposed ice under a shallow cover and the Phoenix lander seems to have exposed ice by the thrust of its landing engines under a very shallow cover:

http://www.space.com/5435-images-phoenix-lander-show-martian-ice.html

I think it may be that the regolith on top is just thick enough to protect the ice from sublimating. We don't really know how all this ice came to be where it is, but there seems to be a lot of it. Maybe the ice is mixed with a certain amount of dust and the sublimating ice then left the dust behind until the dust layer was thick enough to prevent further sublimation.

Quite possible. What was said by NASA specialists during the landing site selection workshop is a minimum of 1m regolith cover is necessary to suppress sublimation in near equator locations where large bodies of water were found. Near the poles it is much less. The Phoenix lander was a polar lander so it is plausible that it found ice under a thin cover.

The dust/regolith won't serve any purpose for us here. If you have deep ice just drilling down 30 meters or more and then melting out caves there and pump up the water would be the easiest way to handle it. Open pit mining would be idiotic because you expose the ice for sublimation then. Even if there is quite a lot of dust mixed in with the ice melting the ice would just leave a layer of stuff on the bottom of your cave.

MRO seems to have found very thick (up to half a mile) quite pure water ice though with its radar in a few places.

We need to research this better though. And go for some ground truth. A precision landed Red Dragon with a drill would be very useful... And a Martian GPS of course. We need to plot all of this very precisely.

Lots of work ahead!

For early ice mining they may well use open pit mining. It is much easier to do and if they keep it shaded loss to sublimation would be minimal. Dig your trenches in south/ north orientation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/17/2016 01:56 am
Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

Why drill vertically when you can drill horizontally? Moving stuff via horizontal roads is notably easier than in vertical ones.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/17/2016 05:29 am
Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

Why drill vertically when you can drill horizontally? Moving stuff via horizontal roads is notably easier than in vertical ones.

It might turn out to be one of those "all of the above" outcomes. If drilling, digging and excavating turns out to be a highly efficient basic form of Martian habitat architecture, then we can expect all kinds of these forms to be tried and also we can expect them to be combined with all sorts of windows, domes and mirror solutions for letting in sunlight, vistas and views.

Bottom line, if we are right that excavating rock is the way to go for large, amazing habitats then expect drilling both vertically and horizontally.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/17/2016 07:14 am
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/17/2016 12:29 pm
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

Here's a calculator: http://www.mide.com/pages/interplanetary-air-pressure-at-altitude-calculator

Depending on air temperature you'd need to drill down to about 150km. You would be way past the crust there and in the mantle. I have no idea what this means in practical terms, but nothing good I guess.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/17/2016 04:22 pm
Mars has no global magnetic field. But I have heard it has localized magnetic fields. I would like to see research on these. Do they locally reduce radiation?

If yes it would be good to put settlements there. Not having to plan for heavy radiation shielding would make many things easier.

Magnetic shielding saves mass, but Martian regolith is a lot easier to come by than superconducting coils.

For example here:

http://www.orionsarm.com/fm_store/RadiationShields.pdf

To reach 0.5 rem/year in a toroidal habitat with 900m diameter and 60m thickness the mass of a magnetic shield is 12x10^6kg while the mass of a passive shield is 12x10^9kg.

So we're talking thousands of tons of superconducting coil vs. millions of tons of readily available regolith.

I don't see how putting a few meters of regolith on top of a habitat is that much of a problem. If the hab itself can withstand the internal pressure you won't actually need much on top, only for shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/17/2016 05:55 pm
Long term I would expect deep shafts drilled down into the crust. Mars is for the most part geologically dead, so drilling down even for miles should be safe in suitable spots. Put a domed roof with windows over the shaft and mount aluminum mirrors around it to allow for daylight (and natural day/night cycles) down there. Grow some suitable plants (vines etc.) on the walls. Carve spiral stairways and terraces into the walls, so our colonists get natural exercise while moving around during the day instead of having to waste time and willpower on exercising with machines two hours a day. Carve horizontal tunnels and caves from the main shaft for living space, workshops and greenhouses (with racks of vegetables) as well as pools with water for growing fish and for swimming.

Why drill vertically when you can drill horizontally? Moving stuff via horizontal roads is notably easier than in vertical ones.

Drilling down gives you a hub to expand from instead of building a rabbit burrow, it can give you a lot of open space with natural light with long lines of sight and some plants all around, it makes mixing of atmosphere easier and it makes drilling down robotically easier, since going down is easier than to drill tunnels. It's all linear, set up a machine and it will go down until you stop it.

Also walking in 0.38g will be awkward, you'll be more jumping than walking anyway so you'll need high ceilings. Having spiral stairs will mean getting around will be great exercise while the workshops and living quarters can be more tight. I know it sounds silly, but at Mars gravity you will need to put load on your muscles and bones to stay healthy and doing this while sweating on machines two hours a day will just not fly in the long run. Better make people run up and down 500m between meals and work (and I guess climbing along nets will make good fun in 0.38g too), they will just do that without heaps of discipline and have fun instead while doing it. Of course you'd need elevators too. People will pass every part of the hab when getting around while seeing most of it all the time. People aren't moles.

But yes, you will also have to go horizontally from that shaft, but as a kind of hub or plaza a naturally lighted shaft with stairs and terraces and plants covering the walls would be better than a network of tunnels. I think.

I'm too lazy to try and do a render, but I think a shaft with 50m diameter and 500m deep with a gathering place with a canteen and plaza on the bottom, spiral stairs and terraces, plants on the walls with workshops, greenhouses and living spaces dug horizontally from the sides could make a place to live. A home to live in, not just a base to survive in. You'd get dawn and sunset, day and night (even weather maybe, you'll be able to see clouds through the roof and you may even get some rain if water from the air condenses on the roof  at night when it cools down), you'd be able to see what people are doing, you'd have space and still never be far from the others, you'd have most the exercise you need just by going through your day. At fridays you can have running and climbing races from the bottom up to the roof (opposite direction for the elders ;-)

But of course if we will find a nice, fat, stable lava tube with a glacier around the corner we would be silly not to take it. There's room for more than one type of hab on Mars.

(Full disclosure: I worked in a deep coal mine for a few years when I was younger. I liked it down there, it was more like a dark forest than like the countryside, but it wasn't bad at all. It was often very quiet and fascinating and no place looked like the other. I hate server rooms much more and I now work as a sysadmin and know what I'm talking about. Living in tin cans with machinery humming all around you all the time doesn't make a home.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Owlon on 10/17/2016 06:47 pm
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

I've had this thought before. It turns out, due to the thermal gradient, the temperature becomes unmanageably high before you get any useful amount of pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/17/2016 09:05 pm
If we drill deep enough, a real long term effort, how deep would we have to go to have enough atmospheric pressure to live in? I think someone has already done the calculation. It would be so deep that we would have to entirely use artificial lighting and energy production to support it. But it should be quite safe without pressure seals.

I've had this thought before. It turns out, due to the thermal gradient, the temperature becomes unmanageably high before you get any useful amount of pressure.

I don't want to doubt your statement, you are likely right. But do we have solid knowledge about the temperature gradient on Mars? We have not done any deep drilling. There may well be other methods than drilling to determin the thermal gradient.
Title: Re: Envisioning Amazing Martian Habitats
Post by: matthewkantar on 10/18/2016 11:04 pm
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/19/2016 08:08 am
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew

I think it's a stretch even for full earth strength people. But a rope with knots for up and a fire brigade pole for down could do the trick. Or a revolving rope for up and down.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/19/2016 11:30 am
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html


Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/19/2016 01:46 pm
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html

All of the MIT buildings in cambridge ma are built on fill. They are 4 to 6 story buildings with 2 basements. They are designed to float on the fill. This was common knowledge at MIT 40 years ago.

Also of note.
One of the skyscrapers of boston has 3 piers on bedrock but the fourth is in fill and they freeze the soil around it to keep it stable. I thought it was the pru of the hancock but haven't found any references yet.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 12:59 am
Mars has no global magnetic field. But I have heard it has localized magnetic fields. I would like to see research on these. Do they locally reduce radiation?

If yes it would be good to put settlements there. Not having to plan for heavy radiation shielding would make many things easier.

Magnetic shielding saves mass, but Martian regolith is a lot easier to come by than superconducting coils.

For example here:

http://www.orionsarm.com/fm_store/RadiationShields.pdf

To reach 0.5 rem/year in a toroidal habitat with 900m diameter and 60m thickness the mass of a magnetic shield is 12x10^6kg while the mass of a passive shield is 12x10^9kg.

So we're talking thousands of tons of superconducting coil vs. millions of tons of readily available regolith.

I don't see how putting a few meters of regolith on top of a habitat is that much of a problem. If the hab itself can withstand the internal pressure you won't actually need much on top, only for shielding.

You need to look up minimagnetosphere.  It's a different concept than the close by superconducting coils.  The power requirements are in the KW range.  There are existing, natural  surface level ones on the Moon.  My worry is that the Martian atmosphere would short the plasma shell and destroy it.  But perhaps not.  If this works, its no regolith and not superconducting coils.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:02 am
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Don't forget inertia. You can jump, but it's also harder to stop once you get going...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:06 am
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html

The most common method is to drive piles down to the bedrock.  If the bedrock is too far, you can invest in wide footings, that eventually end up to be full size, i.e. a raft.  But not much good for tall buildings, because of moment from wind and earthquakes.  That would not be a worry on Mars though.

Melting permafrost is a pain.  Again seems unlikely to happen on Mars in the first few centuries.  But the food production might run fairly hot, and nuclear reactors as well.  Wouldn't want them to sink...

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:09 am
Just found something relevant to a previous post:
In the short term this just means you do not think of yourself as building on a hard surface. Your base should to evolve towards being a buoyant roof in a non-catastrophic fashion.

I wondered how we deal with unstable soil on earth and found this "concrete raft" concept. It also specifically mentions mining as a cause of unstable ground.
http://civilconstructiontips.blogspot.co.nz/2011/06/unstable-ground-soils.html

All of the MIT buildings in cambridge ma are built on fill. They are 4 to 6 story buildings with 2 basements. They are designed to float on the fill. This was common knowledge at MIT 40 years ago.

Also of note.
One of the skyscrapers of boston has 3 piers on bedrock but the fourth is in fill and they freeze the soil around it to keep it stable. I thought it was the pru of the hancock but haven't found any references yet.

And in Boston as well, freezing the soil was used in the Big Dig, and is sometime used in mining to create ice dams in the ground for persistent water infiltration problems.  But these are all temporary systems.  It would be  risky to depend on compressors for long term structural safety.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 01:24 am
One idea I have been wondering about for a few years would be to build a tunnel boring machine on Mars, or the moon.  a 10m diameter boring machine can do more than 700m per month.  Run one of these for 10 years, and you get 84 km of tunnel, that could be arranged into about 1 000 000 m2 of floor.
Run a few for 40 years, and you end up with quite a bit of space.  Probably enough for Musk's million, if food production is in low pressure buildings on the surface.

Need a lot of blades though  ;-)

But you can dig in nice solid rock, rather than loose regolith, and probably have very little risk of leaks.  And don't need to worry about ice melting or not.




Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/20/2016 01:37 am
Melting permafrost is a pain.  Again seems unlikely to happen on Mars in the first few centuries.  But the food production might run fairly hot, and nuclear reactors as well.  Wouldn't want them to sink...
I was referring to a few reasons it might specifically happen on mars though: boring down through say ten meters of regolith on mars to get to the relatively pure ice speculated to exist in buried glaciers near the equator, burying yourself under a thick blanket of regolith which I think would lead to heat seeping into the surrounding ground unless you have complicated cooling to prevent it.

I think you want your waste heat to be exploited melting ice. You should arrange it, not fight it. but then you have to work around this problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/20/2016 03:16 am
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Yes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sdsds on 10/20/2016 05:39 am
build a tunnel boring machine on Mars

I think on Earth these are limited to fairly shallow grades; can't really dig straight down. But with Mars (or Moon) gravity? I wonder how quickly you could get well below the surface?

And how sharply can they turn?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 06:10 pm
build a tunnel boring machine on Mars

I think on Earth these are limited to fairly shallow grades; can't really dig straight down. But with Mars (or Moon) gravity? I wonder how quickly you could get well below the surface?

And how sharply can they turn?
The're used for cars and trains, so very low angles. I expect they wouldn't turn.  They would dig into a wide trench, be dragged sideways, and then start again in the opposite direction, making a whole series of parallel tunnels.

As a specialised form of crusher, it would be interesting to analyse the energy required vs crushing basalt into powder, melting it into fibers and using these fibers in a tension structure.  the actual number of fractures required in large scale boring might be not that high compared to fine crushing.  Perhaps a mining engineer might chip in on this?


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/20/2016 06:27 pm
I've found this interesting document on the closure rates of tunnels in ice sheets.
Closure if a function of pressure and ice creep, that seems fairly independent of temperature, but someone might want to do further research on this.  The images are for an horizontal ice sheet in Greenland, I believe, but the research covers many cases.  At first glance, deformation in Antarctica might be slower.

Anyway, these figures show heavy deformation in just a few years, so I would think twice about building in glaciers, even on Mars.  Ice is not all that stable, it would seem.

Title: Re: Envisioning Amazing Martian Habitats
Post by: zodiacchris on 10/20/2016 07:12 pm
Thanks for posting this! Looking at the lower figure, deep tunnels only show a deformation of 20 cm in 10 years on earth, that is not all that bad. And terrestrial glacier tunnels are not pressurised, while the ones on Mars would be under pressure, which gives an opposing force to the creep, especially under lower gravity.
If braced with pycrete like a mine shaft, or your normal lined tunnel, deformation should not be much of a problem.

I have been in quite a few historical mines, and unless they are braced, collapse and rockfalls are fairly common there, too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/20/2016 08:48 pm
build a tunnel boring machine on Mars

... how sharply can they turn?

The're used for cars and trains, so very low angles. I expect they wouldn't turn.  They would dig into a wide trench, be dragged sideways, and then start again in the opposite direction, making a whole series of parallel tunnels.

The art of digging a hole. (http://machinedesign.com/archive/art-digging-hole)

Quote
TBMs can make turns, but they're not exactly the hairpin variety. By carefully applying more pressure on one side of the cutting head, the machines can change course by about 0.125 in./ft. "A typical radius for a turn is between 300 and 400 ft," says Turner. "But we build special TBMs if jobs call for tighter turns. The tightest radius we ever dug was a 90 turn in 75 ft in a South African gold mine.

Set one off and have it dig in a spiral of increasing radius; then cut across the spiral for linking passageways etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 10/20/2016 09:16 pm
Set one off and have it dig in a spiral of increasing radius; then cut across the spiral for linking passageways etc.

That could be a very efficient use of a small number of boring machines - The one digging the spiral runs nonstop without needing to relocate to keep the tunnel system close together and the radial tunnels could be dug with pretty much whatever equipment is handy whenever one is needed.

A spoke-and-spiral plan allows for most of the work to be done on a very long continuous tunnel with the path(s) from one spot to another  being much shorter. Good for traffic through living/working space and the tailings conveyor for the big TBM never gets very long. If an unstable patch of rock is found just keep going and seal off that section later and abandon it.

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/20/2016 10:28 pm
A spiral would be large. Maybe a good design later. I imagine they start at a cliff and go in there horizontally. Do whatever length is convenient and drill more parallel straight tunnels starting at the cliff again. If you get deep enough into solid bedrock you can make quite large caves. Big spaces will help feel not too enclosed.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 12:04 am
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.
Title: Re: Envisioning Amazing Martian Habitats
Post by: R7 on 10/21/2016 06:48 am
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Sure, for anyone who can comfortably do 3' vertical jumps on Earth...which is very elite club.
Median for average Joe aged 21-30 is 22.1" and 14.1" for regular Jill.
http://jumpshigher.com/average-vertical-jump
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/21/2016 07:51 am
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.

It would be nice and simple. Tunnel boring machines that size don't have the ability to do such narrow turns I believe but maybe they can design them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 11:58 am
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.

It would be nice and simple. Tunnel boring machines that size don't have the ability to do such narrow turns I believe but maybe they can design them.
I agree it is too tight.  I confused diameter and radius :-)  400m radius is the number I should have used.   The bore is probably a little large as well, at 20m.  In a text referenced in earlier posts they mention turns with a 90m radius were made, but its probably not a good idea.
Just imagine a slightly wider spiral.

One interesting characteristic of this idea is that we should be able to cost this fairly easily.  It's the cost of bringing a 400  (?)tonne machine to Mars, plus the cost for a large (2 MW?) solar array to power the tunnel boring machine and power the conditioning system.  A maintenance crew, and the value of the power used for 2 years of operation.  Could serve as a bench mark compared to other solutions

I wonder how large a bubble you can get from 400 tonnes of reinforced plastic, and what might be the mass of a regolith crusher that produced enough material to cover it, produce a stable compression structure to offset the internal pressure and what would be the energy used?

From an urban standpoint, it's a very controlled environment, somewhat akin to an utility model.  Looks like a 1950 theoretical architectural exercise.  Would they sell or rent m3 ?  From an investment standpoint, you should be able to rent out space very early in the project, by closing off completed sections.

Again, I wonder how this would compare to a more organic growth of individual domes/habitats, etc..

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 12:05 pm
The Hard Rock miner's handbook is joined.

This is really used in the industry, and contains all kinds of helpful rules of thumb and design metrics for conceptual designs such as the ones we are looking at here.

Enjoy, quantify and document  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/21/2016 03:01 pm
Well since we're talking about tunnel boring machines again, it's time to go back to my favorite topic!!! :)

https://forum.nasaspaceflight.com/index.php?topic=34667.msg1362562#msg1362562

Very nice post. The mental model is absolutely the right one, in my opinion. Transporting one large machine that will produce tens of thousands of cubic meters of long-lived, reliable, robustly pressurized, radiation-protected habitat enclosures is definitely the way to go in terms of habitat architectures. The energy cost is not a problem, because only energy-rich overall architectures can lead to expanding permanent Martian settlements (anything less would have a too-high risk of dying out). So the problem is reduced to an engineering and logistical challenge of maintaining the TBM in working order, a complex but feasible undertaking for which we already have decades of transferable experience.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 03:43 pm
Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

The illustrated tunnel is a 20m long section.
Floor area  of this arrangement is 27m/m (excluding circulation and linear park).  For a 10 km tunnel, this would mean 270 000 m2 of living area.  So 27m2 per person for 10 000 might be possible, and perhaps not too crowded.

Large public buildings such as schools, stadiums, meeting halls might need a different solution though.

Hardly claustrophobic, IMHO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/21/2016 05:38 pm
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/21/2016 05:58 pm
Spiral city

I'd have another radial tunnel at 90 degrees to the first. Possibly others at intermediate angles; they don't all have to come right to the centre.

Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

Seems a lot of wasted volume. Why do you need three walkways?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 07:04 pm
I'd have thought sealed glassified would have been rather fragile.  why not just bare rock?  Inject grouts into any cracks.
Is there such a thing as a nuclear tunnel boring machine?  All I find is area 51 conspiracy garbage on the subject.  And a weird patent.  Can't we just break the rock, please?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 07:07 pm
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

The tunnel shown is 10 km long.  With your figures, that is 33 x 300 tonnes trips for the ITS.  I think it makes more sense to bring a 300-600 tonne machine (2 trips) to dig the tunnel.  As far as the power required goes, it will be needed anyway after construction for the habitat, so it is not an extra cost.

Tunnels win on this one, IMHO  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 07:13 pm
Spiral city

I'd have another radial tunnel at 90 degrees to the first. Possibly others at intermediate angles; they don't all have to come right to the centre.

Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

Seems a lot of wasted volume. Why do you need three walkways?
You need walkways because you need corridors anyway, and might as well have them out in the 'open'.  You can't move from room to room at this scale of habitat.

Think of the extra volume as buffer space.  Adds inertia to the system.   And it answers some of the worries about confinement that always get raised.  And it's cheap space, because the tunnel boring machine makes a 5m radius bore or 7.5 m radius bore at about the same rate.

You need to keep the bores at least 10m from one another on Earth, for structural reasons.  You can't bring them all to the middle, too fragile.  So yes, just a few all the way through.  The laterals are much tougher to build anyway.  I'm not certain you could actually cross tunnels as I have illustrated.  much easier in 3D space than real space ;-)



Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/21/2016 07:20 pm
First post here, and would like some feedback (gently).

If you give me a heat source and some water, I'm pretty sure I can cultivate life anywhere.  It might be a Dyson sphere, but energy is our challenge on Mars, right?  Your renewable energy sources are solar and wind (especially on the poles?), so to colonize you'd seed with nuclear and develop the others. 

I'll build an ice dome first.  It would be "printed" using water ice and a radial arm, and would embed a continuous fiber with each layer of accretion.  If you pressurize the inside, the tendency will be for the ice to "creep" past the fiber thread that surrounds the perimeter of the dome, but that's okay.  I might not need the fiber at all, since it only has to last a few months.

Why?  That's my growing season.  I make the walls (3D printed, remember) to be like Fresnel lenses, focusing the sunlight toward the center of the dome.  At the poles, I have a relatively CONSTANT rate of radiation for some time.  You need X amount of watts per square meter?  I make a dome X size (60m?), focus the light toward the center, and have a tiny (10m?), thin bubble of plastic to diffuse it, retain some heat (internal greenhouse, within my dome.  No wind in there), and enjoy 24/7 sunlight while my crops grow.  Need less light?  Then add pigment (like red dirt??) to your water as your dome is being formed.

I'd colonize the poles first.  And if someone would spot me about $40mil, I'd build what I'm discussing in Antarctica.  Six months on, six months off. 

Okay, fire away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 07:24 pm
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/21/2016 08:07 pm
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

The tunnel shown is 10 km long.  With your figures, that is 33 x 300 tonnes trips for the ITS.  I think it makes more sense to bring a 300-600 tonne machine (2 trips) to dig the tunnel.  As far as the power required goes, it will be needed anyway after construction for the habitat, so it is not an extra cost.

Tunnels win on this one, IMHO  ;-)

I'm sure a lot of tunneling will be done but at first it will be much easier to build pressure vessels on the surface. That thermal tunneling machine hasn't even been demonstrated on Earth. Too many unknowns to remotely evaluate the feasibility. Welding steel panels together is simple.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 08:15 pm
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

The tunnel shown is 10 km long.  With your figures, that is 33 x 300 tonnes trips for the ITS.  I think it makes more sense to bring a 300-600 tonne machine (2 trips) to dig the tunnel.  As far as the power required goes, it will be needed anyway after construction for the habitat, so it is not an extra cost.

Tunnels win on this one, IMHO  ;-)

I'm sure a lot of tunneling will be done but at first it will be much easier to build pressure vessels on the surface. That thermal tunneling machine hasn't even been demonstrated on Earth. Too many unknowns to remotely evaluate the feasibility. Welding steel panels together is simple.
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.
I'm not talking about short term habitation; I'm talking about what is needed for 1 000 000 people.
that being said, a single large steel building might be just the ticket for an initial habitat, then turned into another function, then eventually abandoned as it ages.  as happen today on Earth.  In that case though, steel would be a waste of carrying capacity.  Might as well use something stronger, to save on weight.  Should be able to make the same dome with 100 tonnes of carbon fiber reinforced plastics.
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/21/2016 08:27 pm
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/21/2016 08:44 pm
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.
I'm not talking about short term habitation; I'm talking about what is needed for 1 000 000 people.
that being said, a single large steel building might be just the ticket for an initial habitat, then turned into another function, then eventually abandoned as it ages.  as happen today on Earth.  In that case though, steel would be a waste of carrying capacity.  Might as well use something stronger, to save on weight.  Should be able to make the same dome with 100 tonnes of carbon fiber reinforced plastics.

ITS will be a mass-rich but volume-limited architecture... I say use the mass. Steel sheets should be a easily manufactured and recycled commodity on Mars, so once there are maybe 3 or 4 habs that size which would have room for ~1000 people) should not be necessary to send any more.

AFAIK there's no way to join pre-fabbed carbon composite panels together with near-parent material strength on site in extreme cold & near vacuum - welding in those conditions is a lot more straightforward. Nor is there a simple way attach interior and exterior structures, or to recycle them at end of life. Plus, carbon fiber is much worse in compression/shear/puncture loads, so piling regolith on top is sketchy.

If you want a semi-permanent large composite hab, take the engines off a ITS ship, lay it down sideways in a trench, push regolith over it, and build decks inside the pressure vessels and prop tanks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 08:47 pm
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours. 

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?
Not all plants grow correctly with 24h sunlight.  I'm working currently on an ... industrial medicinal plant production facility (60 000 ft2) ... and it will be operating on 12 hour shifts, lights on/lights off, since the rest period is required for maximum plant production.  The optimum light level for the plants is 250 W/m2 using halogen lamps, and almost 50% of the energy turns into latent heat, as the plants need to evaporate for their production/growth phase. 
Plants in the wild have long rest periods, when they do not add much mass, and poor productivity compared to what can be achieved under controlled conditions with artificial lighting.
As an interesting aside, the plants also need a certain amount of wind to stir them up everyday, of their stalks do not develop properly and they eventually collapse under their own weight.

 
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 08:52 pm
I think the fresnel lens info is buried in the external link, or maybe in my head I just assumed that the ridges in the wall doubled as lenses as well as structure for the print head to move on.

I'm really dubious of ice holding pressure. Its use as radiation protection, structural support, light gathering, and constant maintenance seem enough without relying on it for something so critical. At least to start with.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 08:57 pm
I think we may need to look into dividing the habs into different phases of exploration. I like the ice house ideas for initial deployment, dragon sized to single ITS landings per location per synod. The TBM (Tunnel Boring Machine) hab ideas seem further down the line, once there are multiple ITS landings at each location per synod.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 09:03 pm
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.
I'm not talking about short term habitation; I'm talking about what is needed for 1 000 000 people.
that being said, a single large steel building might be just the ticket for an initial habitat, then turned into another function, then eventually abandoned as it ages.  as happen today on Earth.  In that case though, steel would be a waste of carrying capacity.  Might as well use something stronger, to save on weight.  Should be able to make the same dome with 100 tonnes of carbon fiber reinforced plastics.

ITS will be a mass-rich but volume-limited architecture... I say use the mass. Steel sheets should be a easily manufactured and recycled commodity on Mars, so once there are maybe 3 or 4 habs that size which would have room for ~1000 people) should not be necessary to send any more.

AFAIK there's no way to join pre-fabbed carbon composite panels together with near-parent material strength on site in extreme cold & near vacuum - welding in those conditions is a lot more straightforward. Nor is there a simple way attach interior and exterior structures, or to recycle them at end of life. Plus, carbon fiber is much worse in compression/shear/puncture loads, so piling regolith on top is sketchy.

If you want a semi-permanent large composite hab, take the engines off a ITS ship, lay it down sideways in a trench, push regolith over it, and build decks inside the pressure vessels and prop tanks.
300 tonnes of steel fits into 100 m3 with space to spare.  There should be something like 1000m3 in a cargo ITS, no?  Not that limited in volume.
I agree the joints might be an unsolvable problem.  And welding on Mars should at least be free of oxydation problems  :-)  Talk about an inert atmosphere.
However, it should be possible to create tension resistant connectors for carbon fiber panels, and then seal the joints with silicone?
I believe the ITS tanks will actually be built for higher pressures than 100 kPa.  And need lots of fancy work to resist the liquid oxygen.  So something of a waste, no?

Trench and cover construction is an alternative to using tunnel boring machines, and despite its apparent simplicity, it doesn't actually always win out against TBM construction.  TBM are not much good for subway stations though, or their martian equivalent, and that is where I think trench and cover might be compatible with the tunnels, allowing for larger spaces for public needs.

Steel is wondefully ductile, but you can mitigate the risk of breaking carbon fiber structures by doing what they to on Earth for fiber glass underground fuel tanks (or should do, not all contractors are honest!) and grade material according to size, and only use very fine materials for the first layer neat the structural cylinder.

Again digging is not all that more efficient than boring.  Specially if you don't have cheap explosives handy.




Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2016 09:06 pm
I think we may need to look into dividing the habs into different phases of exploration. I like the ice house ideas for initial deployment, dragon sized to single ITS landings per location per synod. The TBM (Tunnel Boring Machine) hab ideas seem further down the line, once there are multiple ITS landings at each location per synod.

Absolutely, it's not one size fits all.  And location will likely play a part as to what materials are available on site.  Giving priority to volatiles, or illumination (energy) might limit what is available for buildings.

To refer to the title of this thread, Amazing Martian Habitats will probably not be what we call the first construction shacks :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/21/2016 09:30 pm
I dunno, I find the idea of any hab that uses in situ resources to increase its livable space pretty amazing! The more near term and realistic the more amazing it seems.

I've read a lot of sci fi so tented over valleys, lava tubes, tunnels and domes all seem rather old hat ;)

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/21/2016 09:39 pm
What structure doesn't require some maintenance?
I brought up one a few posts back though you might consider it academic since we are not fish. Gravity tends to order things into layers by density.
Containing water under an oil layer on Mars (http://forum.nasaspaceflight.com/index.php?topic=40628.msg1555177#msg1555177)

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/21/2016 10:08 pm
There won't be a one size fits all solution. A variety of habitat types will exist in parallel. Tunnel boring is a great way of operating but it needs solid rock to work in. People will want a view of their environment available. Even the best flatscreen would fill that psycholocial need. Will there be suitable rock at the landing site, near enough to water? Probably yes but it needs to be part of the site selection. There will be surface habitats, steel, aluminium or composite.  I also believe there will be ice cave habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/21/2016 10:19 pm
I like the oil layer idea, and wondered if anything would be able to decrease sublimation without decreasing the melting point too much.

I haven't browsed all the threads, so I'm not sure if this is covered, but nature may have an answer to what a colony could look like.  Want to see a settlement with lots of domed roofs that functions as a colony?  Just look at a wasp's nest.  Scale it up by several thousand, lay it flat and build it out of ice.  The advantage is that the roof stays under compression and not tension, and tension is minimized to the perimeter of the nest.  The perimeter could be canyon or valley walls.

As a side note, using smaller hollow "spheres" of water ice to build might accomplish a lot in terms of insulation and creating a pressure gradient from the inside to the outside.  Think of it as concentric circles, with the pressure in each one holding a fraction of the psi more than the one outside of it.  No, ice may not hold a full 14.7, but if I had 30 layers of "honeycomb" made from hollow spheres of ice, and each layer had .5 psi more pressure than the one before...you get the point.  I'm just creating a laminate for my dome, really, and the gradient never exceeds the breaking pressure on any one layer. 

I'd rather not exceed the thickness where my lower wavelengths would be absorbed in the ice.  I need some infrared to make it through, but I can't hold pressure if I stay thin. 

Anyone care to spot me $40 mil so I can test this in Antarctica?  Most of that is for the nuclear reactor I'll need, of course...  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/22/2016 12:23 am
You definitely want to use carbon fiber not steel, perhaps toughened. But it is 10 times stronger for the same weight as steel. And is good in compression, too.

Or other fibers whose properties are enhanced at lower temperatures. For instance, Dyneema (UHMWPE) has just as high strength to weight ratio but usually isn't used for aerospace since it eventually creeps under load at room temp and doesn't work well at elevated temperatures. But with Mars' cold temperatures, it's a perfect material and a stupendous radiation shield and it monomer (ethylene) is actually the easiest plastic monomer to synthesize on Mars, so can be eventually produced via ISRU. It's also translucent so lets in sunlight.

A dome is sent in panels, and can be designed for easy construction, including joining..
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/22/2016 12:40 am
I'm opposed to sending any more construction materials than are absolutely necessary. 

Send a robotic habitat builder.  Drop it near a glacier.  Build domes of ice.  From space, it's going to look like honeycomb.  Synthesize the polymers you'll need to make the ice work as a transparent construction material.  Automate crop growth.

THEN send people.  Until we successfully grow food there using the materials present, it's just a one-way trip.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/22/2016 12:56 am
That's not required if we have a decent spaceship, like SpaceX's ITS spaceship or NASA Langley's Hercules. It can be a two-way trip even before we're growing "crops."
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/22/2016 01:10 am
I'm opposed to sending any more construction materials than are absolutely necessary. 

Send a robotic habitat builder.  Drop it near a glacier.  Build domes of ice.  From space, it's going to look like honeycomb.  Synthesize the polymers you'll need to make the ice work as a transparent construction material.  Automate crop growth.

THEN send people.  Until we successfully grow food there using the materials present, it's just a one-way trip.

It's not a one way trip if you can come back; at worst you fail and need to return.  But it would be a good idea to send the fuel production facility and make certain you at least have the return fuel. 
People do have a certain usefulness ;-)  but perhaps I'm biased.
Food is not all that heavy, it's really water that is the problem, usually, and Mars is stuffed with the stuff.
That's one of its good points compared to the Moon.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Aussie_Space_Nut on 10/22/2016 03:10 am
I expect that the first habitats on Mars will be flown in aluminium cans of one form or another. Sole purpose to support the construction crew while they build the first "permanent" habitats.

I like steel as others have suggested for these first "permanent" habitats. Yes steel made on Earth and ferried to Mars. Perhaps Stainless Steel?

https://en.wikipedia.org/wiki/Nissen_hut#/media/File:Munition-store.jpg (https://en.wikipedia.org/wiki/Nissen_hut#/media/File:Munition-store.jpg)

These Nissin Huts are still "up" since WW2 even in what I imagine is a somewhat corosive setting.

I think a "Nissin Hut" designed specifically for Mars is easily doable. Covered with regolith for radiation protection. The WW2 versions had a concrete floor but perhaps for Mars a steel one would be better.

Once you have a decent sized work crew living in the Nissan Huts you can begin major works. I especially like the Tunnel Boring Machine concept.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/22/2016 05:20 am
I think a "Nissin Hut" designed specifically for Mars is easily doable. Covered with regolith for radiation protection. The WW2 versions had a concrete floor but perhaps for Mars a steel one would be better.

I think they would have a pipe shape. Much easier IMO to make them pressure self contained than anchor them in the ground and have those anchors take all the force of atmospheric pressure.

Maybe the shape as seen in the planetary society, is easier to build large pressure vessels. Oil or gas tanks for your home may be horizontal but the large storage facilities of the oil companies have a shape that may be more suitable for a large self contained pressure vessel.

I see this long Nissen hut shape for very low pressure greenhouses that use sunlight with transparent covers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/23/2016 11:09 am
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?

The temporary fiber-reinforced ice domes which focus sunlight to their center are an interesting and imaginative idea. In terms of feedback, I had two points.

The first is that another solution to the "Mars will need a lot of energy, right?" premise is to design all Martian durables, from spacesuits to habitats, to be as long lived and reliable as possible. Since every durable product has embodied energy within it, a tunnel bored into soft rock by a machine will have the energy cost of its construction amortized over its expected lifetime of hundreds of years whereas a temporary fibre-reinforced ice dome will last only months. So maybe from this perspective it is cheaper energy-wise to tunnel into rock with light and heat from nuclear, instead of building temporary ice domes for greenhouses with "free" light and heat from the sun.

The second is that if the real shortage on Mars turns out to be people. (i.e. labour hours) rather than energy, there is less value in creating temporary buildings which produce energy but require maintenance. I don't expect Mars to have shortages of energy because it is easy and essential for Mars to be an energy rich place anyway. So Mars will probably rely heavily on nuclear in its energy mix, though Musk was wise to avoid sharing that "detail" now, which come think of it might explain why he didn't talk about how people will live there at IAC.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/23/2016 11:37 pm
You guys pretty much nailed it with the tunnels and the forest of domes:

ElonMuskOfficialCEO of SpaceX • 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: mfck on 10/23/2016 11:49 pm


ElonMuskOfficialCEO of SpaceX • 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

I fail to imagine tunneling droids powered by electrical batteries, PV or Nuclear charged. Is the power density of current SOA batteries enough for industrial scale mining ops? I assume 'droids' to mean autonomous systems, though.

Are they planning on some Methalox ICE for ground ops? How feasible one would be?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/24/2016 12:23 am
Power density is more than enough. And the biggest mining equipment today is already directly electrically powered with cables, for instance the largest mobile machines in the world, bucket wheel excavators.

There's this false idea that electric is "ninny" while real stuff is ICE powered. That doesnt fit with reality and hasnt for a while.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/24/2016 12:32 am


ElonMuskOfficialCEO of SpaceX • 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

I fail to imagine tunneling droids powered by electrical batteries, PV or Nuclear charged. Is the power density of current SOA batteries enough for industrial scale mining ops? I assume 'droids' to mean autonomous systems, though.

Are they planning on some Methalox ICE for ground ops? How feasible one would be?
Actually, tunnel boring machines are remotely powered.  As are the big shovels on mining sites.  At 4500V or so, you can have a really long extension.  Don't need batteries.  Large PV array, step up station to 4500V (or whatever the DC or AC current will be chosen for distribution) then aluminium cables with a tough outer shell.
see the picture bellow of the power cable for a big mining shovel.

Nothing very exciting happens in tunneling, most of the time.  So remote operation should be ok.  Semi autonomous.

Methalox is not logical, since you need to produce it from the PV or nuclear reactor anyway.  Might as well use the electrical power directly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: mfck on 10/24/2016 12:39 am
Aha! Thanks for the correction, both.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/24/2016 12:45 am
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?

I don't understand the desire to build something which is inherently not stable and needs maintenance even when idle.

If you build stuff on Mars, it does not mean you have to do everything in some "new" and "imaginative" ways. Quite a number of old boring methods from Earth may work just fine. After all, they are the result of thousands of years of experimentation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/24/2016 12:55 am
I don't understand the desire to build something which is inherently not stable and needs maintenance even when idle.

Largest space for minimum landed mass. Specifically geared towards initial habs.

For levels of maintenance think roomba or pool cleaning robots.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/24/2016 01:23 am
We can ISRU all kinds of stuff. That means we don't need unstable structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/24/2016 04:17 am
We can add transparent geodesic domes to the list of amazing habitats after the AMA on reddit.

http://imgur.com/a/NlhVD

From page one: Initially glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 10/24/2016 05:03 am
Just a reminder; MRO and Opportunity found montmorillonite, an aluminum bearing clay, at Endeavour Crater. Aluminum ceramics make a very strong "bulletproof glass" almost as tough as sapphire. Some can stop a .50 BMG.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/24/2016 03:19 pm
About mining droids. A reddit poster

https://www.reddit.com/r/spacex/comments/591rj1/rspacex_elon_musk_ama_answers_discussion_thread/d95380m/

suggested continuous miners for mining and for habitat building. I think they may be better suited for carving out habitats than a tunnel borer. They can build any size and shape, including narrow bends.. They are smaller, though still massive. Many of them could be sent instead of one tunnel boring machine.

(http://www.coaleducation.org/technology/Underground/images/Joy_Mining/12CM27.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 10/24/2016 03:39 pm
I don't understand the desire to build something which is inherently not stable and needs maintenance even when idle.

Largest space for minimum landed mass. Specifically geared towards initial habs.

I'm not convinced that ice habitats have minimal mass requirements for supporting tools.

Quote
For levels of maintenance think roomba or pool cleaning robots.

I'm thinking more along the lines "it fails in 3-10 years".
There were people with the same fancy ideas of living in the ice. And they had enough $$$ to actually try it:

https://www.youtube.com/watch?v=NnBG37CPDLI
https://en.wikipedia.org/wiki/Project_Iceworm

Yes, on Mars it may be more stable. The key word is "may".
As opposed to habitats built with rock/cement/basalt fiber/plastics/steel, which we *know* would not melt.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/25/2016 01:22 am
I am not recommending the thermal tunnel machine.  I think it is magic tech.  I'm describing a standard (if large) tunnel boring machine with metal cutters. 500m per month, as described in earlier posts.

It's by far the simplest means of creating both habitation spaces and sealed spaces.  Remember that the colonists don't have any industrial base up there.  You always need to think of the simplest solution requiring the fewest shipments to the surface that can last the longest and provide the most protection.  If you can combine all of these elements with one expensive piece of machinery, it becomes solely an accounting problem and not an engineering and industrial base availability problem.

We know without a doubt that they will have power.  Parts, building materials, and supplies are another matter entirely. Soil vitrification is a well understood technology- as are TBMs. As long as they have a sufficient power source, they can create pressurized habitation areas that will last for millennia without the magnitude of replacement parts of a conventional TBM, and without the need for pressure vessels shipped all the way from Earth.  Think about the difference in living space expansion if only one trip is needed instead of 10 for the same cubic pressurized space.

You guys pretty much nailed it with the tunnels and the forest of domes:

ElonMuskOfficialCEO of SpaceX • 43m
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

What, you don't think he lurks from time to time on NSF?  Silly person... ;)

It's the nuclear part that doesn't convince.  And I don't really see the point in the vitrification either.  Don't see why it will be tougher than the rock, since it is made from the same material.  Why vitrify crystallized rock?  Might well be required in regolith or in loose soil though. Since that is not structural.  But we should be able to find places with less fractured rock, basaltic areas, perhaps, or some early sedimentation, metamorphic rock that has been reheated into suitable tough, but not too tough, material.

As far as melting goes, won't melting points/elements wear out as well?  High temperature materials are notoriously fragile... Since no thermal boring machine exists, how can we know that they will last longer than the ones we do know about, that we already use and that we can plan for? 

A few tonnes of spare cutters seems a whole lot cheaper than inventing a thermal tunnel boring machine, IMHO.
Crushing is something we have down to a fine art.  Melting in the field, not so much.  Seen many rock melters on construction sites recently?

I think it's just a convergence of ideas.  The best solutions pop up here, as  they probably pop up in the brainstorming sessions at SpaceX.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/25/2016 03:10 am
There is a general argument in favor of Martian machines which are based on simple and well understood technology: the longer you can keep that machine going with the labor and spare parts you will have available in [...Mars Base Alpha  ;D] the more the useful output you will get from that machine over its lifetime and the bigger the contribution it will make towards making Mars Base Alpha self-sustaining. From this perspective, the bar is very high for machines which are still at low TRL's.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/25/2016 03:21 am
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/25/2016 04:15 am
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/25/2016 05:03 am
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.

Thanks.

Apparently compressed air (up to a few bars) is often used in tunnel construction the keep to water out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 10/25/2016 05:44 am
Some pictures from the CERN cavern excavation. Looks relatively "simple". You'd need a pressurized hab to cover the access shaft.

(http://d29qn7q9z0j1p6.cloudfront.net/content/roypta/370/1961/831/F11.large.jpg)

(https://www.dywidag-systems.com/uploads/pics/DSI_Switzerland_Geneva_CERN_03.jpg)

(http://hep.phys.sfu.ca/openhouse_2008/kiosk/gallery/atlas_photos/selected-photos/detector-site/underground/0002017_04-A4-at-144-dpi.jpg)

End result:

(https://mediastream.cern.ch/MediaArchive/Photo/Public/2003/0309030/0309030_02/0309030_02-A4-at-144-dpi.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: iengineerit on 10/25/2016 06:20 am
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...


I'm pretty sure the hab in the second post or any other post makes no mention of using water ice to magnify solar radiation.  As for sublimation, the rate is lower at colder temperatures.  Find a place where water ice is already on the surface and start there.  The equator may get more sun, but not for as may consecutive hours in a given season.

The negative effects of sublimation can be overcome by adjusting the temperature and pressure inside the dome.  The strand of fiber that was laid during the accretion phase of the dome construction serves as your tensile strength - like in pykrete - to "hold back" the water ice from strain failure.  If the dome is under pressure, the ice will want to "creep" past these fibers, and will creep faster as you approach the melting point.  Fine.  By maintaining the inside of the dome (adding water to areas that creep the most, or thin the fastest) you can keep the structure intact.  What structure doesn't require some maintenance?

The temporary fiber-reinforced ice domes which focus sunlight to their center are an interesting and imaginative idea. In terms of feedback, I had two points.

The first is that another solution to the "Mars will need a lot of energy, right?" premise is to design all Martian durables, from spacesuits to habitats, to be as long lived and reliable as possible. Since every durable product has embodied energy within it, a tunnel bored into soft rock by a machine will have the energy cost of its construction amortized over its expected lifetime of hundreds of years whereas a temporary fibre-reinforced ice dome will last only months. So maybe from this perspective it is cheaper energy-wise to tunnel into rock with light and heat from nuclear, instead of building temporary ice domes for greenhouses with "free" light and heat from the sun.

The second is that if the real shortage on Mars turns out to be people. (i.e. labour hours) rather than energy, there is less value in creating temporary buildings which produce energy but require maintenance. I don't expect Mars to have shortages of energy because it is easy and essential for Mars to be an energy rich place anyway. So Mars will probably rely heavily on nuclear in its energy mix, though Musk was wise to avoid sharing that "detail" now, which come think of it might explain why he didn't talk about how people will live there at IAC.

Thank you for the feedback.  I'll agree that a rock structure will last longer, but I'm not sure that temporary (seasonal) structures will not have their place.  Going back to the "honeycomb" view from space, I'll offer another constraint: pollination.   A beehive can presently pollinate around 5 acres of land.  Sooooo....each dome would represent a fixed portion of that area.  Oddly enough, if you can build an ice dome here on earth, reduced gravity on Mars SHOULD make it easier to build a larger dome.  It might not be 1000 feet in diameter, but an array of 7 domes (center one with beehive, six surrounding it) each with a diameter of 300 might work.  Space bees, anyone?

The consequence of growing food inside of an ice dome that could fail is...frozen food?  Seriously, in a new settlement on earth your garden might be bigger than your house.  I can sleep in a lot more places than I can cultivate; growing food is going to be the challenge.  You there, Elon?  Spot me a 10MW thermal, 2MW electric SSTAR and a glacier with some rock at a latitude higher than 74 or so, and I'll build a city out of ice.  Just drop me off in the fall and give me six (cold) months.   ;-)

One of you might be the first person on Mars.  I'm going to be the first person to eat a Martian chicken sandwich.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/25/2016 12:43 pm
Tunnels are a great idea and completely obvious when you think about it, which is probably why Elon-"first-principles"-Musk says Mars Base Alpha will be made with tunnels. It should definitely be possible to make interior cladding with ISRU techniques, one way or the other (with melting, with mixing cement, even with bricks).

Another huge advantage of tunnels is that by placing your town in exactly the right place you can conceivably tunnel over to a landing pad (far away from small, fragile surface domes) and also tunnel over, and down, to water supplies.

In one fell swoop tunnelling deals with the radiation problem, the cost-per-cubic-metre problem, the resource problem and the pressurization problem. All with well-known tech.

The Graduate was told that "plastics" was the future. I think a future Mars Graduate will be told that tunnelling is!   
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/25/2016 03:31 pm
Nice National geographic poster, Mars map and an interesting view of an early colony, with a lava tube.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/25/2016 09:26 pm
You can probably fit a 4m diameter tunnel boring machine on an ITS. I think that tunnel boring is a lot harder than is being presented on this thread, though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 10/25/2016 09:36 pm
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.

Thanks.

Apparently compressed air (up to a few bars) is often used in tunnel construction the keep to water out.

You also won't need breathable air during construction. If you find a suitable place (no cracks in the rock) you can start pretty soon to pressurize your tunnels and shafts with compressed martian atmosphere (CO2) which would make many things easier (even cooling your machinery) and the crews working with breathing masks is much more practical than in full pressure suits.

It would be a good idea though to start with prospecting for suitable spots. You need water and solid but not too hard rock. Sedimentary stone would be ideal probably, if it is cemented. Sandstone is easier to work. Landing a small fleet of Dragons with drilling equipment, ground-penetrating radar and seismic sensors would help a lot with charting what you've got there.

Or just land a small crew on a glacier to refuel their ship and have them do the prospecting. Having a clear long-term goal ("living on Mars") has a way of focussing your efforts that open-end research rarely delivers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: S.Paulissen on 10/25/2016 09:48 pm
Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.
Because the equipment can be operated in a pressurized environment, just like some mining operations on Earth.

Thanks.

Apparently compressed air (up to a few bars) is often used in tunnel construction the keep to water out.

You also won't need breathable air during construction. If you find a suitable place (no cracks in the rock) you can start pretty soon to pressurize your tunnels and shafts with compressed martian atmosphere (CO2) which would make many things easier (even cooling your machinery) and the crews working with breathing masks is much more practical than in full pressure suits.

It would be a good idea though to start with prospecting for suitable spots. You need water and solid but not too hard rock. Sedimentary stone would be ideal probably, if it is cemented. Sandstone is easier to work. Landing a small fleet of Dragons with drilling equipment, ground-penetrating radar and seismic sensors would help a lot with charting what you've got there.

Or just land a small crew on a glacier to refuel their ship and have them do the prospecting. Having a clear long-term goal ("living on Mars") has a way of focussing your efforts that open-end research rarely delivers.

I invite you to open your eyes (and any exposed mucus membranes) in high concentration CO2.  You will not be a happy camper.  Even relatively low concentrations of CO2 are not very pleasant conditions to be in, mask or no.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/25/2016 09:52 pm
I was thinking the same about a CO2 atmosphere but was not sure. If a mask covers your eye and your mouth well, I thought it might be possible.

Also fuel ISRU will yield a lot of nitrogen and argon as byproduct. If you use that it would be better. But if you lose too much of it that would not be good. You need it for building atmosphere of your habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/25/2016 09:54 pm
Still good enough if your eyes are covered by the mask. Or you can fill with nitrogen and Argon which are plentiful in Mars' atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 10/25/2016 11:43 pm
It's worth noting that the carbon monoxide content on Mars is 55,700ppm, which is 2 orders of magnitude higher than than the 667ppm to cause "seizure, coma, and fatality", and 3 orders of magnitude higher than the OSHA limit of 50ppm.  Exposure is cumulative over a 5 hour time period.

If it were raw atmosphere being pressurized, you'd need something that seals very very well if not a pressure suit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/26/2016 12:00 am
It's worth noting that the carbon monoxide content on Mars is 55,700ppm, which is 2 orders of magnitude higher than than the 667ppm to cause "seizure, coma, and fatality", and 3 orders of magnitude higher than the OSHA limit of 50ppm.  Exposure is cumulative over a 5 hour time period.

If it were raw atmosphere being pressurized, you'd need something that seals very very well if not a pressure suit.

For tunnel boring, maybe it will be teleoperation as far as possible and if people need to be physically there then they will be in these new-style pressure suits which are more comfortable to work in.

You can probably fit a 4m diameter tunnel boring machine on an ITS. I think that tunnel boring is a lot harder than is being presented on this thread, though.

I agree that tunneling will be hard, but the payoff is huge in terms of the quantity, quality, connectivity and longevity of the pressurized volume, so it seems like the kind of challenge worth rising to.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/26/2016 01:19 am
Well, look at that! A vitrification machine.  Fascinating.
Subsurface planar vitrification?  I still don't see how that makes the caves stronger though.  Glass is a fragile material. There appear to be carbonates on Mars, this was probably also discussed no end but is Martian cement and concrete possible?

I agree we are throwing tunnel boring machines about in this discussion with wild abandon. A brave soul might perhaps do a spreadsheet of construction costs on Mars?  Distances, masses, energy?  Technological readiness?


As far as Lava tubes go, why not just grind down the living area?  That would solve the sharpness issue?  Anyway, if this has been discussed before, I won't go over it again.  It does seem a bit premature to write off an idea that has never been investigated, and Mars may have had some erosion in the past for some of the caves...

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/26/2016 01:57 am
It's worth noting that the carbon monoxide content on Mars is 55,700ppm, which is 2 orders of magnitude higher than than the 667ppm to cause "seizure, coma, and fatality", and 3 orders of magnitude higher than the OSHA limit of 50ppm.  Exposure is cumulative over a 5 hour time period.

If it were raw atmosphere being pressurized, you'd need something that seals very very well if not a pressure suit.
But Mars' air has even more oxygen with it. That means you could catalytically oxidize the CO to CO2 without extra energy (potentially even harvesting energy that way).
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/26/2016 08:18 pm
For a very early hab - what about something that's like a tennis bubble? It could be more easily stowed onboard inside the ITS cargo space.

(https://www.ssprd.org/portals/0/Littleton%20Golf%20and%20Tennis/LittletonTennisBubble.jpg)

(http://arizonstructures.com/wp-content/uploads/2013/02/slide03.jpg)

The entire thing could be inflatable for ease of deployment. Just stamp the ground flat first. Inflatable arches would provide initial structural support, later reinforced by cables.

Gives you a lot of floor space to work with.

You would expand by erecting more bubbles adjacently and linking them for a contiguous workspace

(http://www.thefarleygroup.com/userContent/images/Blog%20Photos/Cary%20Leeds.Exterior%20Aerial%202.jpg)

Perhaps the Bigelow/Transhab type of multi-layered composite would be adequate protection from micro-meteorite strikes - although for big ones you're SOL.

The only thing better would be a lava tube, but those would probably come later, since they'd require quite some time to prepare and convert to a larger living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/26/2016 09:05 pm
For a very early hab - what about something that's like a tennis bubble? It could be more easily stowed onboard inside the ITS cargo space.

The only thing better would be a lava tube, but those would probably come later, since they'd require quite some time to prepare and convert to a larger living space.
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.
Joined here are a few calculations for dome design.  I have added a column for flexible dome design.  It uses steel, but it should be a good analog for carbon fibre woven cloth plus insulation.  For a 100m radius dome, I'm getting about 10000 tonnes.  A 50m radius dome would be much lighter, you can test this if you want with the spreadsheet.

Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/27/2016 06:57 am
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/27/2016 07:30 am
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.

That same internal pressure he mentioned will require some serious pegs. Mars' atmospheric pressure is 0.6% of earth's. To keep a dome inflated on earth, you need the internal pressure to be slightly higher than the outside. Even if your dome isn't perfectly airtight, it's easy to compensate continuously. But even at the lowest pressure that would be somewhat comfortable for humans (the partial pressure of oxygen in earth's atmosphere), any air leak would cause explosive decompression.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/27/2016 07:47 am

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.

Because of the high loads. Assume only 200m². Then it is already 2000t force to be contained by the anchors. Tent pegs won't handle it, even if you use thousands of them. You would need to make every single anchor 100% safe or better use enough that any one can fail and the neighboring ones can take the load. I think it is much safer and easier to deploy using a habitat that self contains the forces by continuing all around the internal space.

Domes would require a major construction effort for the anchors and you still need to seal them airtight at the ground level. I understand the geodesic dome mentioned by Elon Musk as not providing much radiation protection. That would be done by the building inside. Which is ok, it has much less constraints in costruction than a pressure hull which does radiation protection too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 10/27/2016 01:17 pm
Inflatable buildings need to be buried.
The weight of 3 feet of dirt ranges between 210 to 330 lbs/sq.ft.
A dome 10ft in diameter and 8ft high has a surface area of 358 sq.ft. or  load of 38 to 59 tons.
A half cylinder 10ft in diameter and 16ft long has a surface area of 660 sq.ft. or a load of 69 to 109 tons.  The internal pressure of this cylinder at 14psi is 600 tons.
So piling on about 6ft of regolith will keep wall construction reasonable. 

The alternative is building with really thick reinforced walls as in a Bigelow B330 (or XBASE) if you want to be on the surface

(edited to replace snow with dirt)
Title: Re: Envisioning Amazing Martian Habitats
Post by: AncientU on 10/27/2016 01:52 pm
Inflatable buildings need to be buried.
The weight of 3 feet of dirt ranges between 210 to 330 lbs/sq.ft.
A dome 10ft in diameter and 8ft high has a surface area of 358 sq.ft. or  load of 38 to 59 tons.
A half cylinder 10ft in diameter and 16ft long has a surface area of 660 sq.ft. or a load of 69 to 109 tons.  The internal pressure of this cylinder at 14psi is 600 tons.
So piling on about 6ft of regolith will keep wall construction reasonable. 

The alternative is building with really thick reinforced walls as in a Bigelow B330 (or XBASE) if you want to be on the surface

(edited to replace snow with dirt)

Is the goal here to reduce statistical deaths from radiation, or kill people in cave-ins so that they don't have a chance to acquire a radiation-related illness?  Tunneling is also a high risk undertaking (no pun intended)... hell, going to Mars is, too.

We are focusing too narrowly on one risk...
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 01:56 pm
Anchoring this to the ground is much harder than on Earth.  And the internal pressure would force the use of carbon fiber materials, probably.

Why would anchoring be more difficult? What force is working against you? I'd imagine it would be anchored with tent pegs hammered into the ground, or whatever they do for tennis bubbles here on Earth.

The idea is to have a quickly and easily deployable structure. A more robust permanent hab could come later.

That same internal pressure he mentioned will require some serious pegs. Mars' atmospheric pressure is 0.6% of earth's. To keep a dome inflated on earth, you need the internal pressure to be slightly higher than the outside. Even if your dome isn't perfectly airtight, it's easy to compensate continuously. But even at the lowest pressure that would be somewhat comfortable for humans (the partial pressure of oxygen in earth's atmosphere), any air leak would cause explosive decompression.

THIS is why I suggest Bigelow style materials for such a structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/27/2016 02:08 pm
THIS is why I suggest Bigelow style materials for such a structure.

Yeah, that's what I suggested too - what's wrong with the Transhab multi-layered walls? If they can handle the pressure difference relative to the hard vacuum of space, then why would Mars be worse than that?
Title: Re: Envisioning Amazing Martian Habitats
Post by: ThereIWas3 on 10/27/2016 02:14 pm
what's wrong with the Transhab multi-layered walls?

They are really bulky to ship.  The walls on a Bigelow module are about 1 foot thick, and that part is not what collapses for launch.  And they are complex to manufacture.  Using local materials is a better idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 02:39 pm
what's wrong with the Transhab multi-layered walls?

They are really bulky to ship.  The walls on a Bigelow module are about 1 foot thick, and that part is not what collapses for launch.  And they are complex to manufacture.  Using local materials is a better idea.

It would be better... Long term.

      For the initial base camp and the first colonists, who will be setting up and working with the equipment to make these sort of structures, the use of Transhab style structures, even with their thick walls, would be the most suitable and SIMPLE system to set up.

      Part of the whole issue here is simplicity.  The more complex you make the set up of the initial habitats, the longer people have to be outside, increasing the probability of accidents.  This also tends to prevent the transfer of personnel to the base camp itself, for a longer duration than needed.

      The more basic the set up and construction of the base camp / first colonial structures are, the more time available to set up other things, like in situ fuel, air and water production, the setting up and initial operation of hydro or aeroponic systems for food and additional air recycling, setting up interior habitat structures, power generation systems, and maybe even a bit of scientific exploration.

      Thin walled inflatables also will run a MUCH higher risk of structural failure and tears.  A thick walled structure would be more fault tolerant and provide a significant insulation and radiation protection factor, before being buried with regolith, as time would permit.  The thick walled structure would also allow for higher internal pressures, should it be desired, than thinner walled inflatables.

      While the Transhab type structures suffer from a somewhat higher mass and bulk penalty than thin walled inflatables, the advantages would seem to far outweigh the disadvantages.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/27/2016 02:50 pm
Cover & Cut

Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.

True.  One reason to start with a broad pressurized dome on bedrock:  expansion can be accomplished without tunneling.  Simple interior surface excavation can do it.  That is, "cut" beneath the pre-existing "cover".   

The simplest case would be a spiral ramp excavation.  For example, ramp-cut beneath a dome's "hanging garden", to add another garden terrace level.  A 2-m cut under a notional Lake Matthew 300-m water-sealed dome expands the garden by ~13 acres.  No tunnel boring, sealant application, reinforcement or vitrification would be required.  Relatively simple.
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/27/2016 05:05 pm
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.

But once you've gotten deep enough, you could dig out through the sides without adding more domes.q

However, all this tunnel-boring stuff is much, much more difficult than building pressure and radiation resistant domes and arches out of marscrete blocks and/or vitrified regolith blocks, and adding an airtight layer to the inside. Especially because nobody has mentioned the supply train that gets the heaps of waste material out of the pressurized area in a meaningful amount of time required to make working in a pressurized area advantageous.

Cranes and concrete are thousands of years old building techniques. Sure, the cranes would likely contain pressurized areas, or at least be controlled remotely from those areas. These techniques are far easier to scale up as the colony grows, and need a far smaller industrial base for maintenance and spare parts, and thus would require less support from home.

Tunneling on earth is not an easy job. When things go wrong, it takes months to solve the problem on Earth, with humanity's entire industrial base less than 24 hours away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/27/2016 05:17 pm
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.
...
I'm very curious about what the domes are going to be attached to, as they will be under an enormous amount of tension (and definitely not compression) at the ground once pressurized.

Anchoring a half-cylinder or half-sphere at the ground is going to be very difficult; IMO it's almost certainly better to trench down and lay a full cylinder/sphere, so you aren't relying on the ground as part of the pressure vessel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/27/2016 05:31 pm
Zipper Truck Tunnels

...nobody has mentioned the supply train that gets the heaps of waste material out of the pressurized area in a meaningful amount of time...

Cranes and concrete... are far easier to scale up as the colony grows...

Speaking of, how about Zipper Truck tunnels?  Could be an efficient way to build bulk airlocks, and to speed entry and exit of the presumably robotic "dump trucks" and entrained open-box beds during expansion work. 

Zipper Truck tunnels would be sealed and weighted, concrete/sinter construction.  > 100 m length, with one-way traffic.  Multiple dump trucks and entrained beds would queue in the tunnels for concurrent airlock entry/exit, minimizing airlock operation time. 

"Git 'er done."

https://www.youtube.com/watch?v=7ns5UBd0gls
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/27/2016 06:53 pm
Bedrock

Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.

Basaltic bedrock is pretty tough.  You'd have to excavate a long, long way down to reach a depth that needs reinforcement.

(https://patternsofnature.files.wordpress.com/2012/05/kulnura_quarry_basalt_columns_nsw_3.jpg)

Related:  Bedrock fractures shouldn't pose a problem for pressurization if leaked gas is recaptured at the surface.  A lightweight, perimeter-sealed but unpressurized canopy, such as 25-micron ETFE, could capture the fractures' leaked gas overhead.  Pressure under the canopy would equalize with the atmosphere as a pump returns leaked gas to the dome.

Also works for outgassing water and ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 10/27/2016 08:09 pm
What about thin-walled inflatables where you could pump foam inside the walls as the "inflating" material?

Foam is mostly air/gas by volume, so the foam-producing reagent would store/transport compactly.

You pump your foam into the thin-walled envelope, which will help the foam take on the desired shape. No fuss, no muss. Wiring, plumbing, etc would already be sewn into the envelope as well. There envelope would also have hardpoints to attach the airlock and other hardware, if they aren't already fused to the envelope.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 10/27/2016 08:33 pm
What about thin-walled inflatables where you could pump foam inside the walls as the "inflating" material?

Foam is mostly air/gas by volume, so the foam-producing reagent would store/transport compactly.

You pump your foam into the thin-walled envelope, which will help the foam take on the desired shape. No fuss, no muss. Wiring, plumbing, etc would already be sewn into the envelope as well. There envelope would also have hardpoints to attach the airlock and other hardware, if they aren't already fused to the envelope.

Put in very simple terms, something inflated to ~14.7psi(or any significant fraction thereof) with only ~0.087psi of atmosphere countering that force will pop like an over-inflated balloon unless the material is very strong or a large amount of weight(like regolith, bedrock or ice) is piled on top of it to simulate all of the air that is piled on top of everything here on Earth.  The problem gets worse as the volume inside the inflatable gets larger.  Using a weak material and piling stuff on top of it is perhaps not a great idea, because then it will collapse if it loses pressure.

Edit: If you think that a ~14.6psi pressure differential sounds trivial, consider what would happen to most structures here on Earth if you drew a near vacuum inside of them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 08:36 pm
What about thin-walled inflatables where you could pump foam inside the walls as the "inflating" material?

Foam is mostly air/gas by volume, so the foam-producing reagent would store/transport compactly.

You pump your foam into the thin-walled envelope, which will help the foam take on the desired shape. No fuss, no muss. Wiring, plumbing, etc would already be sewn into the envelope as well. There envelope would also have hardpoints to attach the airlock and other hardware, if they aren't already fused to the envelope.

      Interesting idea, but what would the puncture resistance be for the final structure?  Tensile strength would also likely be an issue, even allowing for internal pressure.  Especially is you plan on burying the structure.  You also have the issue of void spaces forming during the foaming process.  Trust me, I've tried to do something similar to what you suggested in a home improvement project.  Needless to say, it didn't really go as planned.

       Mind you, I am not saying that the Transhab structures should be a permanent solution, nor should it be considered as much more than a base camp structure, but they are a workable structure that would meet most of the needs for such a base camp.

      Longer term, I've considered the mixture of some form of polymer with the local regolith, to form a sort of polycrete material.  it could be foamed as an insulation material and possibly used as a direct analogue to concrete.  I considered a plastic base, primarily, because most, if not all of the needed materials and resources, to make a wide variety of polymers is readily available in the local environment.  This, then could be used to make blocks, rafter structures and domes or spheres as needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 10/27/2016 08:45 pm
Cover & Cut

Can anybody name me a reason why to use boring instead of cut-and-cover? The reasons why cut-on-cover often cannot be used on Earth do not apply on Mars.

Also TBMs are huge machines. They weight 1000s of tons and its parts won't fit into ITS.

Construction/mining equipment for vacuum operation has never been developed. Even the most basic machinery will be expensive as hell.

True.  One reason to start with a broad pressurized dome on bedrock:  expansion can be accomplished without tunneling.  Simple interior surface excavation can do it.  That is, "cut" beneath the pre-existing "cover".   

The simplest case would be a spiral ramp excavation.  For example, ramp-cut beneath a dome's "hanging garden", to add another garden terrace level.  A 2-m cut under a notional Lake Matthew 300-m water-sealed dome expands the garden by ~13 acres.  No tunnel boring, sealant application, reinforcement or vitrification would be required.  Relatively simple.

Problem is, you're still going to have some out-gassing through the local soil, due to about three billion years of low surface pressure.  It may not be a lot, but it will still happen.  There's also the possibility of nasty chemical reactions with the surrounding soil.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/27/2016 09:51 pm
There's also the possibility of nasty chemical reactions with the surrounding soil.

That is one point I worry about a bit. What if a slow but steady trickle of oxygen gets into the bedrock and it contains compounds that can oxidise, change the volume and cause problems? Not that I know anything about it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/28/2016 04:45 am
I think you would still want to use some sort of spray on sealant as a barrier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/28/2016 05:37 am
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.
...
I'm very curious about what the domes are going to be attached to, as they will be under an enormous amount of tension (and definitely not compression) at the ground once pressurized.

Anchoring a half-cylinder or half-sphere at the ground is going to be very difficult; IMO it's almost certainly better to trench down and lay a full cylinder/sphere, so you aren't relying on the ground as part of the pressure vessel.

I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 10/28/2016 06:11 am
Well, reinforcing the sides won't hurt, or you risk weakening the foundations the dome rests on. And you want to have done very intensive preparatory geology to make sure there are no faults or other weaknesses in the bedrock that either feed back to the surface or weaken the outer 'wall', or the entire thing goes south fast.
...
I'm very curious about what the domes are going to be attached to, as they will be under an enormous amount of tension (and definitely not compression) at the ground once pressurized.

Anchoring a half-cylinder or half-sphere at the ground is going to be very difficult; IMO it's almost certainly better to trench down and lay a full cylinder/sphere, so you aren't relying on the ground as part of the pressure vessel.

If the process of creating those triangles and supports between are straight forward enough, perhaps the dome should have a bottom half that is not made of glass.  Yes, it would involved excavating a large hole, but at least you wouldn't have the major concern of anchoring.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/28/2016 07:39 am
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/28/2016 09:23 am
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.
I couldnt find good numbers of that. Is transparency through glass similar to though fibre optic cable? You can get values like 1dB/kilometer.
http://www.thefoa.org/tech/loss-est.htm
https://en.wikipedia.org/wiki/Decibel
Title: Re: Envisioning Amazing Martian Habitats
Post by: high road on 10/28/2016 10:22 am
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.

If you've got no radiation protection outside of the inner buildings, you can't exactly go outside unprotected either. Or at least very limitedly to limit the amount of radiation exposure. How does that justify the effort of building a giant dome? The construction equipment for the dome will have a larger mass than decoration and screens to give an 'outside' feeling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/28/2016 10:38 am
I still assume radiation protection in the dome. Should makr it more than thick enough to compensate for the pressure.

To compensate for pressure that wall needs to be ~10m thick. If you do that little light gets through glass. I also don't think you can look through 10m of glass which is the biggest reason to use glass in the first place. Plus you would have to build that structure strong enough to stand up when not pressurized too. I assume that radiation protection would be provided by the roof of the building inside.

If you've got no radiation protection outside of the inner buildings, you can't exactly go outside unprotected either. Or at least very limitedly to limit the amount of radiation exposure. How does that justify the effort of building a giant dome? The construction equipment for the dome will have a larger mass than decoration and screens to give an 'outside' feeling.

It's very important to be able to see outside and to have access to natural sunlight. The living and working spaces can be excavated vertically and horizontally into rock for radiation protection, with geodesic glass domes creating green, naturally lit environments connected into the network of tunnels. Geodesic glass domes can also be mounted on cliffside openings to create spectacular panoramic vistas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/28/2016 11:48 am
If you've got no radiation protection outside of the inner buildings, you can't exactly go outside unprotected either. Or at least very limitedly to limit the amount of radiation exposure.

An hour or two every day on average are not a problem at all. Radiation hazard is constantly overhyped. Don't go out during a solar outburst.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/28/2016 12:10 pm
Martians are going to have to get used to radiation. Think of all the time people will be outside doing construction work. They will have to sleep and play in shielded areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 03:37 pm
If you're significantly below the "datum" on Mars ( which you most likely will be as almost half the surface is and all the places where it's easy to land are), then neither micrometeorites nor solar flares are a problem because even the thin Martian atmosphere brings micrometeorites to a safe velocity and blocks almost all the solar flare.

Carry on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/28/2016 06:53 pm
Flare

If you're significantly below the "datum" on Mars... then neither micrometeorites nor solar flares are a problem because even the thin Martian atmosphere brings micrometeorites to a safe velocity and blocks almost all the solar flare.

Solar flare proton energy exceeds 100 MeV. 

(http://www.projectrho.com/public_html/rocket/images/radiation/flare02.jpg)

And as previously noted (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1587381#msg1587381), at energies above ~20 MeV, the flux of cosmic ray protons is increased by interaction with the martian atmosphere.  The lower the site, the greater the high-energy flux.

It would appear to be a significant problem for surface habs. 

Protection from that high-energy flux requires meters of shielding mass, or, conceivably, an artificial magnetosphere (https://arxiv.org/pdf/1406.1159v2.pdf), generated within a bubble of ionized gas.  In-atmosphere, the ions would require confinement.  Perhaps membrane + magnetic field confinement; that is, confining fields generated inside some novel high-strength balloon fabric.  ( ? )

(https://www.researchgate.net/profile/Ruth_Bamford/publication/262920173/figure/fig6/AS:296049034973204@1447594998914/Figure-6-The-deflection-of-a-high-energy-ion-green-by-the-electric-field-E-r-red.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 07:27 pm
Nope. Even the worst flares are dramatically attenuated by the Martian atmosphere which averages over 40g/cm^2 (the fact that flares are still relatively anisotropic helps in this case) at typical landing locations. That's more than enough.

You can see this by looking at MSL's radiation data for transit vs surface. The flares are still detectable over ambient, but the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 07:41 pm
As you can see, 30 g/cm^2 of aluminum shielding protects against all acute effects of even the worst flares. CO2 is a much better shield than aluminum, and te average Mars atmosphere thickness over the entire Mars sky (by solid angle) is over 40g/cm^2 (and remember we can do this because flares are still fairly isotropic) at attractive landing sites, plus flares are attenuated at Mars' distance from the Sun.

Source: http://www.bioedonline.org/slides/content-slides/space-life-sciences/radiation-effects/?pageaction=displaySlideDetails&tk=56&dpg=13
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/28/2016 08:36 pm
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  A "3% risk of exposure induced death (REID)" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/28/2016 08:41 pm
I have been thinking about water overhead for shielding. It could also serve to equalise the heat between day and night, avoiding constant flexing of your pressurised container.

If the optimal shielding is only a meter or two it could still let you see the sky and and I think it could be quite aesthetic. Admittedly my aesthetic runs more to sharks with lasers.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/28/2016 08:50 pm
I have been thinking about water overhead for shielding. It could also serve to equalise the heat between day and night, avoiding constant flexing of your pressurised container.

If the optimal shielding is only a meter or two it could still let you see the sky and and I think it could be quite aesthetic. Admittedly my aesthetic runs more to sharks with lasers.  :)

It might have to be ice so it wouldn't boil if exposed to martian atmosphere
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/28/2016 08:53 pm
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  An "excess risk of 3% for fatal cancer" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that cancer mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.

It depends on what the colonists considered an acceptable risk. A man who is a heavy smoker (two packs a day), after fifty years, has a 15% change of getting lung cancer. That doesn't stop millions of smokers.

I think the additional risk would be acceptable for establishing a base, but if Musk and his supporters want Mars to be a backup for humanity, a colony will need enough shielding to get the radiation risk down to low levels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 10/28/2016 08:53 pm
About a decade ago I worked with some ~40" glasses-free 3D 1080p plasma displays that shifted perspective 9 times as you walked around them.  They required(and displayed) 18 video inputs.  They worked pretty well, for any number of people from differing viewing geometries, simultaneously.

Every time I read about the importance of windows in the ITS and transparent elements of habs being psychologically important on this site, I think back to those.  I've read "but displays are no substitute for a window" with regard to the ITS many times.

A quick google shows that the technology hasn't died yet, but I don't see many offerings that take so many inputs(just 2 for the ones I see at first glance, consumer-facing.)

I don't see why this technology couldn't be improved upon even further than the 9 perspectives, given a forcing function to do so.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/28/2016 08:55 pm
Deep Blue

I have been thinking about water overhead for shielding. It could also serve to equalise the heat between day and night, avoiding constant flexing of your pressurised container.

If the optimal shielding is only a meter or two it could still let you see the sky and and I think it could be quite aesthetic. Admittedly my aesthetic runs more to sharks with lasers.  :)

You might not be the only NSF guy with a shark-and-laser aesthetic.   :)

But even without the sharks, yeah.  And you realize the sky overhead would be blue, as seen from within? 

(http://thumbs.dreamstime.com/t/closeup-view-metal-structure-dome-clear-glass-roof-blue-sky-fragment-background-54227629.jpg)

Plus, even under 5 m of water you could get 60% light transmission:  enough for 3 harvests each summer, maybe (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1524017#msg1524017).
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/28/2016 10:51 pm
It might have to be ice so it wouldn't boil if exposed to martian atmosphere
In this case I was thinking room temperature because it is acting as a buffer to keep temperature stable, so it would have to be inside your pressurised volume. I was thinking you might have fish in it, or use it for swimming also. I think a big swimming pool would be a great addition to a habitat. A hundred meters is a small area to walk in but a large area to swim in.

At the most extravagant it could be a level above your entire habitat. At the least extravagant it could be pools above your homes.

Im not sure to what extent just having a body of water solves the expansion and contraction problem. Biosphere 1 had bodies of water but still had this issue. Fountains might help keep air and water temperatures in sync?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/28/2016 11:09 pm
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  A "3% risk of exposure induced death (REID)" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.
I was talking only of acute effects, which we have the best evidence of. I'm specifically referring to solar flares, which if shielded by Mars' atmosphere have a negligible impact on total dose and thus REID. So what you're talking about is irrelevant to my point: that Mars' atmosphere tames solar flares.

You're left with GCR and secondaries from that, but that is a different discussion and is not what I was talking about.

Again, solar flares are essentially stopped (for our purposes) by the Martian atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/29/2016 02:56 am
3%

...the total event-integrated dose is FAR lower than free space, basically shielding the astronauts from all acute effects.

"Acute"?  Radiation exposure doesn't have to induce vomiting and seizures to be unacceptable.  A "3% risk of exposure induced death (REID)" is a common limit, as in Rapp 2006 (http://www.marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf) and Cucinotta et al. 2013 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797711/).

What studies conclude that the excess risk to multi-year crews is < 3%?  That is, what studies conclude that mortality would rise < 3% under Mars' increased high-energy flux, without meters of hab shielding? 

If no studies reach that conclusion, we can only think that the shielding is justified.
I was talking only of acute effects, which we have the best evidence of. I'm specifically referring to solar flares, which if shielded by Mars' atmosphere have a negligible impact on total dose and thus REID. So what you're talking about is irrelevant to my point: that Mars' atmosphere tames solar flares.

You're left with GCR and secondaries from that, but that is a different discussion and is not what I was talking about.

Again, solar flares are essentially stopped (for our purposes) by the Martian atmosphere.

I was looking for a supporting study, not a repetition.

A 100+ MeV proton will penetrate the martian atmosphere, whether it's a solar flare proton or a galactic proton.  We shouldn't expect one to be "tamed" like a kitten, while the other rips through flesh like a lion.  The assertion doesn't make sense to me.

Also, an unspecified acute radiation symptom is not a lifetime REID 3% statistic.  REID stats are in common use at NASA.  Consider those stats when thinking about solar flares, and Mars radiation risk generally.  Shielding on long-duration Mars habs must be designed to protect for a lifetime.

And -- just to make sure -- you're not thinking of low-energy solar wind protons or solar storm protons, are you, Robotbeat?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/29/2016 02:32 pm
Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/29/2016 03:59 pm
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/30/2016 10:40 am
What habitat building parts and equipment should the first few ITS flights carry?

So far, some of us talked about inflatables or other kinds of more or less pre-fabricated habitats, while others talked of constructed habitats such as tunnels, ice caves and transparent domes.

We talked a little bit about what equipment should be on the manifest for the first flights (e.g. tunnel boring machines) but I feel there's more to it. What would your manifest strategy be for the early flights, so that your vision of an amazing habitat could be realized?
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 10/30/2016 11:56 am
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/30/2016 02:55 pm
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?
Look at the graph an link I posted earlier.

Also, I you want to be precise, flares/storms is not the technical term used. Solar particle events is the term used. And again, look at the diagram I attached and the link I posted above.

Mars' atmosphere does indeed attenuate solar particle events to levels where you don't need to be concerned with them. That was my original claim (reworded to use slightly more technical language), and I was defending that, not making claims about GCR in that statement. Also, micrometeorites also by a concern.

I'm bringing those up because people keep mentioning solar particle events and meteorites as relevant to habitat design, but they aren't unless you build at high altitude (i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: mmeijeri on 10/30/2016 03:11 pm
(i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.

Citation needed. Propulsive landing isn't especially difficult at higher altitudes. It's easier to get research grants for fancy aerodynamic deceleration however.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/30/2016 05:58 pm
(i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.

Citation needed. Propulsive landing isn't especially difficult at higher altitudes. It's easier to get research grants for fancy aerodynamic deceleration however.
It takes MUCH more propellant to land on Mount Olympus. I'm still talking about ITS-style EDL. If you want to land on the top of Mt. OLympus, you basically have to do the entire landing propulsively, like landing while moving at Mach 8, versus Mach 3 for supersonic retropropulsion. That's a huge difference and means far less landed mass for a given propellant.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/30/2016 09:47 pm
(i.e. Where it's hard to land anyway, like Mount Olympus). GCRs may be a consideration, but SPEs are not.

Citation needed. Propulsive landing isn't especially difficult at higher altitudes. It's easier to get research grants for fancy aerodynamic deceleration however.
It takes MUCH more propellant to land on Mount Olympus. I'm still talking about ITS-style EDL. If you want to land on the top of Mt. OLympus, you basically have to do the entire landing propulsively, like landing while moving at Mach 8, versus Mach 3 for supersonic retropropulsion. That's a huge difference and means far less landed mass for a given propellant.

Could a lifting body vehicle (not ITS) decelerate aerodynamically in the lower atmosphere with a high drag angle of attack and then gain altitude with a high lift/low drag attitude to land propulsively at high altitudes without burning too much propellant? Or is this too nutty to even contemplate?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/30/2016 11:24 pm
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)

Well sure.  Or the hab designers could do a real job.  What's your preference?  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 10/31/2016 12:02 am
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare, or from GCRs for that matter. 

And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)

Well sure.  Or the hab designers could do a real job.  What's your preference?  :)

That would depend upon the frequency and duration of the solar flares (of which I am completely ignorant).  If on Mars surface they are completely random, once a month-ish events, with only 15 minutes of warning, and they last for several hours, I'd want all habitats to be 'flare-proof' for their inhabitants.  If on the other hand, they are once a decade event, with hours of notice, and last only 30 minutes, I don't think it would make sense to drastically increase the cost and complexity of the habitats (and decrease their aesthetics and 'livability', such as burying everyone under meters of opaque regolith). In this case I think an adequate 'storm shelter' would make the most sense.

Which of these two extremes best characterizes the flares?

(And again, I acknowledge this completely ignores the GCR issue.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 12:56 am
View from inside a Martian dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/31/2016 01:04 am
Storm vs. Flare

Look at the diagram I posted. That should answer your question. We're concerned here narrowly with solar storms and with reducing their level until they pose no acute risk. It doesn't have to block the entire spectrum, just the overall level. And even just 30g/cm^2 of aluminum can do that. Mars's atmosphere does even better.

A solar storm proton is not the same beast as a solar flare proton.  Up to 1000x the energy (https://msis.jsc.nasa.gov/sections/section05.htm#_5.7_RADIATION).  That's why the martian atmosphere doesn't protect from the flare
It sure does.

Quote
And I don't know who the "we" is, but what studies if any have actually recommended a mere 30g/cm2 of aluminum shielding (11 cm) for a long-duration Mars hab?
You missed the point. The Martian atmosphere is a better shield than that 11cm of aluminum would be. No shielding is necessary on Mars (unless you're at high altitude) for solar particle events. It's not something to bother considering in your habitat design.

GCR might be (though that's actually debatable), but that's about limiting your total time, not about being "caught out" during a solar particle event.

EDIT:And of course I'm not talking about the relatively slow particles in the solar wind.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/31/2016 05:44 am
Staying Alive, with Aesthetics

wstewart, would (or could) colonists have advanced warning that a solar flare was coming?  If so, does that suggest that their 'normal' habs would not have to protect against them, but that they'd need some type of underground 'storm shelter' to scurry to in the (rare) event of a direct hit by a solar flare?

(Though that still leaves the ongoing, though lower dosage threat of GCRs, yes?)

Well sure.  Or the hab designers could do a real job.  What's your preference?  :)

That would depend upon the frequency and duration of the solar flares (of which I am completely ignorant).  If on Mars surface they are completely random, once a month-ish events, with only 15 minutes of warning, and they last for several hours, I'd want all habitats to be 'flare-proof' for their inhabitants.  If on the other hand, they are once a decade event, with hours of notice, and last only 30 minutes, I don't think it would make sense to drastically increase the cost and complexity of the habitats (and decrease their aesthetics and 'livability', such as burying everyone under meters of opaque regolith). In this case I think an adequate 'storm shelter' would make the most sense.

Which of these two extremes best characterizes the flares?

(And again, I acknowledge this completely ignores the GCR issue.)

Actually I don't know that shielding has to force a "dramatic increase in cost and complexity" of habitats.  Not on Mars, anyway.  Now in flight, mass is precious and shielding is measured by the centimeter in every dimension, with some complexity.  On Mars however, shielding is readily available and essentially free.  Just fill the space, by any means.  It would be dirty work, but all potentially external to the habitat, and therefore not necessarily requiring an increase in habitat cost or complexity.

And I think that shielding work is required, if Mars habitats are going to house multi-synod crews or permanent settlers, and not just single-synod visitors.  Consider for example McGirl et al. 2016 (https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/67500/ICES_2016_59.pdf?sequence=1):  "Crew Radiation Exposure Estimates from GCR and SPE Environments During a Hypothetical Mars Mission".  The study long and short:  female crew members under 40 approach their lifetime 3% risk limit, even on a single-synod mission with 500-day stay.  That's at -7000 m elevation, beneath 15 cm of aluminum shielding. 

Add also the extra risk of poorly-understood HZE particle effects (http://forum.nasaspaceflight.com/index.php?topic=41526.msg1604544#msg1604544), and it's quite possible that most crew members will approach the 3% limit.  Inference being, most crew members would be restricted to one single-synod mission (500 days on the surface).  A two-synod mission (1300 days on the surface) would put all well beyond the 3% limit.

And come to think of it, if those crew members had cis-lunar experience, or any mission experience beyond LEO, their cumulative prior dosage could use up their "margin", and disqualify them for any Mars mission at all. 

Moreover flare events aren't the worst of it.  In the study, GCR doses are 7-18x as great as flare doses, depending on elevation.  (GCRs with nasty HZE wildcards.)   So to win more time on the surface, the crew would need to slash GCR exposure drastically, day-in, day-out.  Flare shelters wouldn't do the job.  They'd have to lay on the hab shielding.

I think.



Each Lake Matthew dome has a notional 5 m water/ice shield.   That seemed... adequate.  ( ? )  That shield would admit ~60% of incident light, at least in summer.  With blue skies.  In winter the ice would capture only a little light.  Reading light, I guess.   

Question:  Could such shielding give adequate "aesthetics and livability"?  Or what aesthetic goals would you prefer to shoot for?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 10:52 am
A busy day at Mars Alpha. A few synods after the first flights.

The mostly underground base (not quite a city yet) has just received a new influx of colonists. 
The solar panel farm is just outside the frame of the pictures.  A glacier a few km away provides the water for the base and fuel production.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 11:00 am
Close up of the ITS-SS.
Title: Re: Envisioning Amazing Martian Habitats
Post by: The Amazing Catstronaut on 10/31/2016 11:43 am
Gorgeous rendering - and possibly quite realistic.

How ballistics resistant/anchored/thermally/vibro resistant would the dome have to be without being prohibitive, to situate the domes closer to the landing zone? There isn't a distance problem as-is; you're going to need good rover capacity anyway.

The domes would be much easier to construct if they were manufactured with local glass. Perhaps with additives brought from earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/31/2016 12:20 pm
The plastic PVB layer used in safety glass could be made on Mars from the air and water. It needs H, CO, ethanol, ethylene and propylene (both made from methane), and ascetic acid. There are fancy ways of making ethanol and ascetic acid using catalysts and electrolysis.

You could make the plastic layer extra thick for strength, thermal insulation, toughness, and even some residual radiation shielding (although it'd have to be very thick, like a foot or a meter or so, to make any significant difference in radiation shielding). The thin glass layers could be shipped (carefully!) from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 12:21 pm
Gorgeous rendering - and possibly quite realistic.

How ballistics resistant/anchored/thermally/vibro resistant would the dome have to be without being prohibitive, to situate the domes closer to the landing zone? There isn't a distance problem as-is; you're going to need good rover capacity anyway.

The domes would be much easier to construct if they were manufactured with local glass. Perhaps with additives brought from earth.
The location illustrated is supposed to be the edge of a volcanic plateau, or the edge of a crater where the rock was properly mixed and melted.  Ideally the rock would need to be hard, but not too hard, so less SiO2, if possible.  If the base could be located near a SiO2 source, ideally sand, to reduce mining energy, that would help with local production of glass.  Hematite spheres could provide iron, but removing the Oxygen would be energy intensive, perhaps there are enough nickel iron asteroids on the surface to provide revenue for roving miners?
I expect the main structural design requirement will be anchoring of the domes due to atmospheric pressure.  Other forces should be minor.  As the ships land pretty much empty of fuel, landing may not be that much of a vibration source.  Take off requires a lot more power, and there is the risk of fuel explosion, so I put the take off pad a bit further away.  There would be a need for some kind of crawler from one pad to the other, perhaps a multiwheel vehicle rather than a caterpillar type vehicle?
I have no idea what is the sound power from a landing, so some of the design elements for airports may not apply.  In the present design I just eyeballed distances based on airports that I have seen over the years.  The underground structure comes from subway projects I have been involved with.  It's basically a big subway station ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/31/2016 12:40 pm
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 12:53 pm
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.
As a transportation infrastructure, I expect a surface road and rovers is less expensive than a tunnel.  The pad won't be used all that much after all, so low traffic.  The pads might be further away, but then they wouldn't fit into the illustration any more.  A little artistic licence there, perhaps. At least I'm not landing Petawatt class spaceships in the middle of cities with km tall towers ;-) 
Title: Re: Envisioning Amazing Martian Habitats
Post by: kenny008 on 10/31/2016 01:04 pm
Might be best to just put the landing pads "around the corner" from the domes.  The domes would be shielded from direct impact from landing / launch debris by an intervening hill, yet still within a reasonable distance.  No real reason for the domes to face directly at the launch site.  Just drive the rovers from the domes, around the corner of the hill, and out to the launch site.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 01:39 pm
Might be best to just put the landing pads "around the corner" from the domes.  The domes would be shielded from direct impact from landing / launch debris by an intervening hill, yet still within a reasonable distance.  No real reason for the domes to face directly at the launch site.  Just drive the rovers from the domes, around the corner of the hill, and out to the launch site.
Would be fun to see the ships land though, I expect it would be quite an event.  There shouldn't be any debris from a normal landing.  A crash might be another matter though, wouldn't want to compound a catastrophe.  If the vehicle has little fuel and is down to a few hundred m/s, will it be a kaboom or a crumple?
Title: Re: Envisioning Amazing Martian Habitats
Post by: kenny008 on 10/31/2016 02:22 pm
Even well-engineered concrete may pretty quickly degrade after a few landings.  Even LZ-1 showed a little damage from the first landing.  I probably wouldn't want to risk a chunk of pad material being flung through my dome.
But yeah, it would look really cool.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 02:31 pm
Even well-engineered concrete may pretty quickly degrade after a few landings.  Even LZ-1 showed a little damage from the first landing.  I probably wouldn't want to risk a chunk of pad material being flung through my dome.
But yeah, it would look really cool.
Could there be a layer of water added to the pad just before a landing?  How quickly would it sublimate, or would it turn to ice and add the danger of flying ice blocks to the danger of flying concrete bits?

If the landing is as precise as on Earth, might just put in a thick mild steel plate at the center of the pad?
Guess it would be logical to just put the landing field further away.  There's no romance in safety.  Sigh.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 10/31/2016 02:45 pm
If the landing is as precise as on Earth, might just put in a thick mild steel plate at the center of the pad?
Guess it would be logical to just put the landing field further away.  There's no romance in safety.  Sigh.

Hide the domes from the landing field. Only a utility entrance needs to face the pads.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2016 03:05 pm
If the landing is as precise as on Earth, might just put in a thick mild steel plate at the center of the pad?
Guess it would be logical to just put the landing field further away.  There's no romance in safety.  Sigh.

Hide the domes from the landing field. Only a utility entrance needs to face the pads.
Don't forget, these are the Amazing Martian Habitats.  Got to stretch the limits a little.  It should feel and look impressive, but be reasonably safe.  What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?  There are a lot of safe angles, and the domes are 500 m away in the illustration.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 12:54 am
My new ellipsoid version of the domes.

Simpler to build.  Less risk.  Now needs an inside, unless someone convinces me these don't look good or will not work  :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/01/2016 01:09 am
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 01:22 am
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
ok I'll find some new land
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/01/2016 02:29 am
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
I think the Martian atmosphere will stop that. But even on Earth, you wouldn't want to be just 600 feet from a landing spaceship of that size! More like several kilometers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/01/2016 04:06 am
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.

Good idea. At 0.38g the debris from a crash / explosion could fly a long way, damaging domes and scouring roads. With the labour constraint and the perpetual need for physical growth on Mars, it will be important to avoid the "broken window fallacy" over there. Here on Earth, we count selling cigarettes and the treatment of the ensuing cancers as economic growth. We're big enough to hide all this mess here, but the physical economy of Mars will not be forgiving of our mistakes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/01/2016 04:22 am
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.
As a transportation infrastructure, I expect a surface road and rovers is less expensive than a tunnel.  The pad won't be used all that much after all, so low traffic.  The pads might be further away, but then they wouldn't fit into the illustration any more.  A little artistic licence there, perhaps. At least I'm not landing Petawatt class spaceships in the middle of cities with km tall towers ;-)

One thing to bear in mind is that Mars will either be an energy-rich and tunneling-intensive place, or else it won't be very much of an inhabited place at all. So if the tunneling machines will be there in abundance and kept busy at all times, their constant use will lead to improvements in their technology.

Also, relative costs of road making vs tunneling here on Earth, where roads are 1000 times more common than tunnels, might be very different on Mars where the surface is a pretty hostile place that is expensive to work in/on.

The attractiveness of tunnels on Mars has a network effect to it, making tunnels on Mars far more valuable than tunnels on Earth. Every additional kilometer of tunnel is another kilometer of pressurized, earth-like environment added to the base. So Mars will be the planet of the tunnels (not the canals, after all)

Relative notions of value that we are familiar with here won't necessarily apply there. At a distance of 10 to 20 light minutes, the price/cost of a product or service on Mars will depend on the Martian economy which is going to have different priorities than the Earth's economy. Things that are expensive on Earth might be cheap on Mars and vice versa depending on the different relative scarcity of each thing on each planet.

To see that point, consider that if there is no Martian economy but instead we bring everything from Earth, then everything you already have emplaced on Mars is "low cost" relative to everything you don't have which would be astronomically expensive. That's why the Apollo 13 astronauts used socks, plastic bags, suit hoses, the cover from the flight manual and bungee cords to connect a square carbon dioxide scrubber to a round hole in their emergency: those items were the only economical items available to them. Everything else that wasn't already there had an astronomical delivery cost and was therefore eliminated from consideration.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/01/2016 07:12 am
One thing to bear in mind is that Mars will either be an energy-rich and tunneling-intensive place, or else it won't be very much of an inhabited place at all.

If their energy supply is twice what is needed for fuel production, it will be energy-rich indeed.

They may be somewhat limited over night.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/01/2016 08:26 am
One or two really big domes, well engineered, it is possible. One for a big stadium where a large crowd can gather and one as a kind of nature park with large trees and animals would be good to have and help make this feel like a home worth working for and living in.

Maybe Martians will not feel the need for a nature park like this but I think they will.

Such structures would come later in the development of the settlement, when most of the materials can be sourced locally. But 10 or 20m domes can be transported. At least a few of them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 08:41 am
Hi guckyfan, I might have just deleted the msg you were replying to. Moved it to the correct thread:
..here..
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/01/2016 01:14 pm
Hi guckyfan, I might have just deleted the msg you were replying to. Moved it to the correct thread:
..here..

OK, I think it happened while I posted. It caused me some temporary disorientation.  ;)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 03:12 pm
I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 11/01/2016 03:20 pm
About a decade ago I worked with some ~40" glasses-free 3D 1080p plasma displays that shifted perspective 9 times as you walked around them.  They required(and displayed) 18 video inputs.  They worked pretty well, for any number of people from differing viewing geometries, simultaneously.

Every time I read about the importance of windows in the ITS and transparent elements of habs being psychologically important on this site, I think back to those.

A voice of sanity.
Millions of people spend weeks or even months on end with no outside view through windows. Tens, maybe hundreds of millions of people have rather crappy scene viewable from their home/office windows (such as a wall of the next building filling the entire view).
This is an invented problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/01/2016 03:33 pm
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/01/2016 03:50 pm
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.

Some people prefer a challenge and money, risk and comfort aren't as important to them as the idea of going where no one else has ever gone.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ch1le on 11/01/2016 04:07 pm
LaMontage.

Can you give me the sketchup link? I might put my vizualisation skills to use and make some renderings. Finally a chance to contribute to this forum.
Best wishes,
M.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 05:22 pm
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks (https://en.wikipedia.org/wiki/Storage_tank) or this big liquid hydrogen tank (http://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration)

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 05:55 pm
I put a bit of structure inside the dome.
btw, elipsoid7 is my favorite. This is how I imagine it, with tiers, and a mall-like atrium in the center.

You could have more wide spaces in the top half, because that inward curving wall is hard to stand up close to. It is actually a bother for normal structures. At least it can give you a wide open sense of space. It is the lower half that is easy to stand next to, so you can divide that up into floors with the wall forming expansive windows. I imagine that area a bit like living in an airport: mall-like, but with wide window-walls looking out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 06:06 pm
This was a bit off topic in the other thread, but I also like the idea of a cellular approach to surface dwellings, if you go that way: https://en.wikipedia.org/wiki/Honeycomb_(geometry)#Space-filling_polyhedra

This would
*allow your bases to grow organically,
*allow construction with uniform components
*allow redundant levels of safety from decompression
*allow repairs and additions without inconveniencing other cells.

You could create interesting varied internal volumes by removing some adjacent faces.
Outer faces could be outward curving, or flat if reenforced with internal cabling. Inner walls could be flat and reinforced with cables for both directions, or curved and designed to be sufficiently strong whether relying on tensile or compression strength.

Longer term I imagine living underground, but these surface areas could be your vertical farms and your parks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 07:36 pm
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks (https://en.wikipedia.org/wiki/Storage_tank) or this big liquid hydrogen tank (http://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration)

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)
You can look at the Wikipedia page "Pressure vessels".  There is a nice, short overwrap pressure vessel.  Or you can look at the propane pressure tank on your barbecue, if you have one. It's pretty stuby.
The vessel will keep its shape because there are no compression forces, all forces push equally towards the exterior and the walls are under pure tension. But yes, an ellipsoid is less mass efficient that sphere.  The strain in about double that of a sphere, or almost equal to that of a cylinder.  So this allows manufacturers to use the same thickness throughout.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/01/2016 10:48 pm
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/01/2016 11:02 pm
You can look at the Wikipedia page "Pressure vessels".  There is a nice, short overwrap pressure vessel.  Or you can look at the propane pressure tank on your barbecue, if you have one. It's pretty stuby.
The vessel will keep its shape because there are no compression forces, all forces push equally towards the exterior and the walls are under pure tension. But yes, an ellipsoid is less mass efficient that sphere.  The strain in about double that of a sphere, or almost equal to that of a cylinder.  So this allows manufacturers to use the same thickness throughout.
Ok: it linked to this: https://en.wikipedia.org/wiki/Head_(vessel)
"Vessel dished ends are mostly used in storage or pressure vessels in industry. These ends, which in upright vessels are the bottom and the top, use less space than a hemisphere (which is the ideal form for pressure containments) while requiring only a slightly thicker wall."

..so it is suboptimal, but apparently only a bit. Im surprised. Does this rely on any 'unbendiness' of the walls? Would these maintain their shape if infinitly strong in tensile strength but fully flexible?.. I think I can see that is true now by imagining constant length chords across the dome. Tensile strength requirements go up, approaching infinity as they approach flatness, but it is not about bendiness (I really should look up the technical term for that :) )
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 11:21 pm
Here is a view of safebase.  With a nice mountain just at the right place.  The landscape is from South Tunisia.
I've added a solar array field to the view.  IF you want, you can imagine an underground nuclear reactor, or not.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 11:29 pm
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/01/2016 11:37 pm
LaMontage.

Can you give me the sketchup link? I might put my vizualisation skills to use and make some renderings. Finally a chance to contribute to this forum.
Best wishes,
M.
Go to the Trimble 3D warehouse and look for ITS Mars Base.
Dome, vehicle, ITS and a hidden astronaut :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/02/2016 01:47 am
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks (https://en.wikipedia.org/wiki/Storage_tank) or this big liquid hydrogen tank (http://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration)

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread? My thinking is that this thread went public with descriptions and pictures of glass domes and tunnels before Elon Musk mentioned them for the first time ever in his AMA. Also everything about geodesic glass domes on Mars is amazing so the entire other thread would be right at home in here. It would certainly make everyone's life easier to have one thread instead of two, we have enough worries each day to also have to worry where to post ideas about amazing glass domes in Mars Base Alpha.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/02/2016 02:28 am
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.
Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 03:46 am
Domo Domo

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread?

Thanks.  Could we merge, but consider keeping this thread open for non-dome structures?  There are a lot of ideas here; wouldn't want to discourage the other ideas, just because Musk tweeted "dome".
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 11/02/2016 04:00 am
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.
Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

Seems it would be straight forward to have a rollout flexible cover that could cover the glass at night or during dust storms.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 04:33 am
Heat Loss

Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

It would be good if I've calculated too high there, because lower heat loss would be a win for many hab schemes.

I was thinking of heat loss as it's calculated in a typical construction.  R-value (thermal resistance) for 6 cm glass works out at ~0.06 m2K/W.  Winter night temperature difference is 160 C. That gives a heat flux of 2667 W/m2

For dome surface area I used your previous scaling number of 150 m diameter, eyeballing a 75 m height, and allowing for 25% dome burial with no heat loss there.  That leaves 36,620 m2 exposed for heat loss. 

Multiply area by flux, and total heat loss is ~100 MW.

The glass panes insulate very poorly, so convection off panes should be low; but if there's a correction factor for atmospheric pressure I don't know it.  Also the dome radiates efficiently because there's no reflector outside the glass surface.

In your spreadsheet you have a smaller dome (100 m diameter), and you're using low-e film.  I think I'd seen that these films, in practice, reduce heat flux by at most 1/3.  Any thought on that?  And you're using the T4 Stefan-Boltzmann law, which is fine.  Just coming at heat loss from a different direction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/02/2016 04:42 am
Domo Domo

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread?

Thanks.  Could we merge, but consider keeping this thread open for non-dome structures?  There are a lot of ideas here; wouldn't want to discourage the other ideas, just because Musk tweeted "dome".
I would prefer them kept separate.. The domes one is about some very specific issues with domes. It is specific enough that it might actually feel answered shortly, and then that thread will fade away while this thread may continue, perhaps now focusing more on the domes and droids and tunnelling aspects.

The thing about that dome thread was specifically issues like anchoring and leaking that made the Dome statement strange to me. Someone did some math about anchoring i havent got around to yet. My expectation is that it is more time, effort and resources for a less trusty and less general result, restricting you to only certain types of ground that may or may not be near the resources you want.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 05:02 am
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/02/2016 10:03 am
Domo Domo

KelvinZero, and posters, do you think it would be a good idea to merge this thread and the geodesic glass domes thread?

Thanks.  Could we merge, but consider keeping this thread open for non-dome structures?  There are a lot of ideas here; wouldn't want to discourage the other ideas, just because Musk tweeted "dome".

Our topic is amazing habitats of all kinds and the equipment you would take to build them. Musk mentioned domes together with "tunelling/mining droids" so there is a lot of room for envisioning either in the direction SpaceX seems to be going or in any other direction that seems amazing to you.

I would prefer them kept separate.. The domes one is about some very specific issues with domes. It is specific enough that it might actually feel answered shortly (..snip..)

The thing about that dome thread was specifically issues like anchoring and leaking that made the Dome statement strange to me. Someone did some math about anchoring i havent got around to yet. My expectation is that it is more time, effort and resources for a less trusty and less general result, restricting you to only certain types of ground that may or may not be near the resources you want.

I still think it's better to merge them but it's a step forward for our posters to have clarity on the topic of the other thread. It sounds like it's for extended discussions on glass dome issues around anchoring and leaking.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 10:27 am
Heat Loss

Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

It would be good if I've calculated too high there, because lower heat loss would be a win for many hab schemes.

I was thinking of heat loss as it's calculated in a typical construction.  R-value (thermal resistance) for 6 cm glass works out at ~0.06 m2K/W.  Winter night temperature difference is 160 C. That gives a heat flux of 2667 W/m2

For dome surface area I used your previous scaling number of 150 m diameter, eyeballing a 75 m height, and allowing for 25% dome burial with no heat loss there.  That leaves 36,620 m2 exposed for heat loss. 

Multiply area by flux, and total heat loss is ~100 MW.

The glass panes insulate very poorly, so convection off panes should be low; but if there's a correction factor for atmospheric pressure I don't know it.  Also the dome radiates efficiently because there's no reflector outside the glass surface.

In your spreadsheet you have a smaller dome (100 m diameter), and you're using low-e film.  I think I'd seen that these films, in practice, reduce heat flux by at most 1/3.  Any thought on that?  And you're using the T4 Stefan-Boltzmann law, which is fine.  Just coming at heat loss from a different direction.
You're missing the convective term on the outer surface of your glass.  In a typical building insulation calculation, you will have the internal film coefficient, the insulation of the building wall composition, then the outside film coefficient, usually equivalent to R 0.1.  However, if you analyse this film coefficient in detail, you will find that it is an expression of the convective conduction from the mass flow of the air on the surface of the building. Q=hAdT where h is a factor of the mass flow.  Using a slightly different equation, Q=mf*Cp*dT, power=mass flow x specific heat x temperature difference, on Mars with the atmosphere 100 times less dense than on Earth, the mass flow will be 100 times less, so the heat transfer film coefficient will be 100 times higher, or about R10 (imperial units) or 2 inches of styrofoam equivalent.  Now if you have double pane glass, you will have 2 more film coefficient, one on the inside and another on the outside of the second pane.  So the overall R will be practically 30.  Therefore the surface temperature of the outer glass pane will be near to the environment temperature, and the radiation will be very low.
And to further reduce heat low you can put the low emissivity film of the inside of the outer glass pane.  This film is an infrared mirror, so the radiation from the inner glass plane gets reflected, and the radiative heat gain on the outer glass pane is almost nil.  Summing up the very low convection and the very low radiation, you get very low heat transfer, about 1000 times less than your first order estimate, or about 100 kW.  For 12 hours of night then about 1200 kWh of heat loss.  As the heat gain is higher, the domes will tend to overheat, if the solar heat gain is not reduced.  So curtains during the day, and not during the night!

The reason low-e windows are not that effective is that they have an atmospheric pressure gas in the void.  If you had a Mars pressure gas in the void, they would insulate as well as, or better, than the walls.  Of course, they would implode first ;-)


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 10:34 am
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Perhaps LDPE would do the trick?  It has a glass transition temperature of -125C.  I was hopping to use it for plastic algae grow tubes on the surface of Mars. 
However, plain glass is a good building material, I don't quite see why it needs to be replaced by plastic, in particular if it is produced in situ.  Shouldn't there be some obsidian flows available on Mars? Good source of glass, that, since it's already glass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 10:51 am
A bit of mining.
Anyone had a look a the Hard Rock Miner's handbook I posted a while ago?
Anyway, a typical 2500 Tonne per day gold mine requires 6 MW electrical, plus about 1/2 of that at the mine itself, as fuel and explosives.  This is to crush rock into a very fine powder, to get the gold out, and to dig into very hard rock, usually with high silicate content.  If we just break the rock into gravel, we can use much less power, let's guess 1 kW/tonne.
Since rock has a density of about 3 tonnes per m3, 1 MW of solar power will extract 300 m3 of rock per day, using standard mining methods.  Over a year, we should be able to create 300x300 = 90 000 m3 of underground volume. 
If we divide this into 4.5 m floors, then we have 20 000 square m of living area, or enough for 1000 people at 20 m2 per person.  In two years, about 40m2 per person.
If someone could check this I would really appreciate it, but I guess i'll start right away on illustrating a few big caves....


Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/02/2016 11:07 am
Very good calculations, lamontagne!
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 12:21 pm
Dome Heat

Heat Loss

Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Why so high?  I was hoping that using a low emissivity on the glass surface would allow for the radiation to be fairly low.  I just calculated something like 100 kW.  I expected no convection or conduction.  Do you have some numbers for this?

It would be good if I've calculated too high there, because lower heat loss would be a win for many hab schemes.

I was thinking of heat loss as it's calculated in a typical construction.  R-value (thermal resistance) for 6 cm glass works out at ~0.06 m2K/W.  Winter night temperature difference is 160 C. That gives a heat flux of 2667 W/m2

For dome surface area I used your previous scaling number of 150 m diameter, eyeballing a 75 m height, and allowing for 25% dome burial with no heat loss there.  That leaves 36,620 m2 exposed for heat loss. 

Multiply area by flux, and total heat loss is ~100 MW.

The glass panes insulate very poorly, so convection off panes should be low; but if there's a correction factor for atmospheric pressure I don't know it.  Also the dome radiates efficiently because there's no reflector outside the glass surface.

In your spreadsheet you have a smaller dome (100 m diameter), and you're using low-e film.  I think I'd seen that these films, in practice, reduce heat flux by at most 1/3.  Any thought on that?  And you're using the T4 Stefan-Boltzmann law, which is fine.  Just coming at heat loss from a different direction.
You're missing the convective term on the outer surface of your glass.  In a typical building insulation calculation, you will have the internal film coefficient, the insulation of the building wall composition, then the outside film coefficient, usually equivalent to R 0.1.  However, if you analyse this film coefficient in detail, you will find that it is an expression of the convective conduction from the mass flow of the air on the surface of the building. Q=hAdT where h is a factor of the mass flow.  Using a slightly different equation, Q=mf*Cp*dT, power=mass flow x specific heat x temperature difference, on Mars with the atmosphere 100 times less dense than on Earth, the mass flow will be 100 times less, so the heat transfer film coefficient will be 100 times higher, or about R10 (imperial units) or 2 inches of styrofoam equivalent.  Now if you have double pane glass, you will have 2 more film coefficient, one on the inside and another on the outside of the second pane.  So the overall R will be practically 30.  Therefore the surface temperature of the outer glass pane will be near to the environment temperature, and the radiation will be very low.
And to further reduce heat low you can put the low emissivity film of the inside of the outer glass pane.  This film is an infrared mirror, so the radiation from the inner glass plane gets reflected, and the radiative heat gain on the outer glass pane is almost nil.  Summing up the very low convection and the very low radiation, you get very low heat transfer, about 1000 times less than your first order estimate, or about 100 kW.  For 12 hours of night then about 1200 kWh of heat loss.  As the heat gain is higher, the domes will tend to overheat, if the solar heat gain is not reduced.  So curtains during the day, and not during the night!

The reason low-e windows are not that effective is that they have an atmospheric pressure gas in the void.  If you had a Mars pressure gas in the void, they would insulate as well as, or better, than the walls.  Of course, they would implode first ;-)

Thanks for the numbers there.  It looks like I was wrong in thinking that because a glass pane insulates very poorly, convection off the pane should be low even at 1 atm. 

As an apples-to-apples cross-check, can you calculate the simple 150-m dome's heat loss your way?  That is, the dome without the improvements of double-panes and low-e film.  If you could calculate that heat loss under 1 kPa atmosphere and under 100 kPa atmosphere, those would be good cross-check reference points.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/02/2016 12:54 pm
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Perhaps LDPE would do the trick?  It has a glass transition temperature of -125C.  I was hopping to use it for plastic algae grow tubes on the surface of Mars. 
However, plain glass is a good building material, I don't quite see why it needs to be replaced by plastic, in particular if it is produced in situ.  Shouldn't there be some obsidian flows available on Mars? Good source of glass, that, since it's already glass.

Isn't the brittle transition temperature more critical?  Both low- and high-density polyethylene transition at -70 C (http://omnexus.specialchem.com/polymer-properties/properties/ductile-brittle-transition-temperature).

And how might an algae grow tube maintain the ~10 C growth temperature range, while radiating and conducting heat out on the surface? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 01:08 pm
Cold Skin

Youre making the same false assumption that you made earlier when you said the polycarbonate would be brittle. You're saying the surface of the dome will be the same temperature as the incredibly thin outside air. That's simply not true.

There's not perfect thermal conductivity between the thin Martian air and the dome's surface.

?  The polycarbonate only needs to reach -60 C at one point on its surface, to become brittle there, and put the dome at risk.  On a typical night with -90 C air and ground, a -60 C cold spot on the exterior surface seems very likely to me.  Especially along the ground, where conduction produces even faster heat loss. 

And heaven forbid the dome heating system should fail even briefly, when a polycarbonate dome's integrity is so fragile at martian temperatures.  (Come to think of it, how would you ensure that the polycarbonate never reached -60 C during construction, when a dome heating system was not yet available?   Logistically, that seems a challenge in itself.)

If you wanted to make an opposite case, and give reassurance that the polycarbonate would never approach -60 C, I suppose you'd need to model 1-D polycarbonate thermal profiles, with thermal front skin depth evolution over 1 sol, both in air and on the ground.  Or is there some model already available, for polycarbonate, polyethylene or some similar sheet material?
Perhaps LDPE would do the trick?  It has a glass transition temperature of -125C.  I was hopping to use it for plastic algae grow tubes on the surface of Mars. 
However, plain glass is a good building material, I don't quite see why it needs to be replaced by plastic, in particular if it is produced in situ.  Shouldn't there be some obsidian flows available on Mars? Good source of glass, that, since it's already glass.

Isn't the brittle transition temperature more critical?  Both low- and high-density polyethylene transition at -70 C (http://omnexus.specialchem.com/polymer-properties/properties/ductile-brittle-transition-temperature).

And how might an algae grow tube maintain the ~10 C growth temperature range, while radiating and conducting heat out on the surface?
Good points, it was notional and not calculated. I'll add this to the response to your earlier question about domes, since the tubes are long skinny domes.  Regarding HDPE, I believe one of the reasons that rovers have metal wheels is that NASA has been incapable of finding a material that remains flexible at all possible temperatures.  So HDPE might fail as you mention. Certainly rubber does.  A very incomplete answer might be that colonists would deploy the algae tubes in summer, when the air is relatively warm, then use redundant heating systems for the tubes.  If the water freezes the tubes will be finished anyway.  Then they would need to store enough food for the required repair/replacement time.
If the base was nuclear powered, then there should be a lot of waste heat to keep the tubes from freezing, but that's another thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/02/2016 01:40 pm
Isn't the brittle transition temperature more critical?
...

Only when toughness is in question, i.e. when under impact. Brittle does not mean "weak", it simply means the material is not ductile. Concrete and granite are brittle materials.

Polycarbonate, for example, is MUCH STRONGER at 4K than it is a room temperature, even though it's not nearly as tough.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/02/2016 09:23 pm
I still think it's better to merge them but it's a step forward for our posters to have clarity on the topic of the other thread. It sounds like it's for extended discussions on glass dome issues around anchoring and leaking.
There is also cross linking to other posts. I actually like threads that end. I hate threads that go on for a hundred pages where the good stuff gets buried, and then the topic gets rehashed again. Rehashing can be irritating, being told you are rehashing and this was all covered 100 pages back, and "didn't you read it??" is also irritating :)

OFF TOPIC:
I just had what I think is an AWESOME idea. Imagine if some threads were simply impossible to post to more than once? But you can reedit your post as often as you like.

These would become like thesis threads. Everyone has their thesis, whether on radiation, moon vs mars or other pet ideas. Whenever a topic starts up say on radiation again.. rather than repeating arguments over and over, you link to your thesis and just make some comment about the particular relevant part in it, and you polish your thesis in response to comments and counter arguments.

Im convinced that the quality of online discussion is largely shaped by details of forum technology. It is a very interesting topic all of it's own. Currently, it is a jungle out there. Someone could come up with the right idea and it might revolutionise how the human race manages knowledge as significantly as the scientific method did.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/02/2016 11:37 pm
Here is my calculation of the various domes.

It was a bit more complex than expected, since I needed to convert the external film coefficient into the actual convection coefficient, and then iterate manually  on a continuity formula, where Conduction in glass = Radiation+ external convection.

Anyway.
A 75m radius on Mars gains 16 MWh in a day at 45 degrees north.
For a single pane glass dome and Earth pressure external atmosphere, the loss is 300 MWh per day.
For a single pane glass dome with Martian external pressure, the loss is 73 MWh per day.
For a double pane glass with low emissivity film and a martian pressure air gap, the loss is 7 MWh per day.

So we need the low emissivity film and we need the second glass pane.

Similar results for a plastic film algae growth tunnel. 2mradius 200m long
For a single wall, gain is 750 kWh, loss is 7500 kWh, so perfect as a nuclear reactor cooling system, not so good otherwise.
For a double wall with low E film and a low pressure air gap, the loss is 350 kWh.  So no secondary heating required and the tube in a net energy gain.

These are commuter train time calculations, so there may be errors, take with a grain of salt.  But I think it's probably pretty close to reality.


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 04:54 am
Toughing It Out

Isn't the brittle transition temperature more critical?
...

Brittle does not mean "weak", it simply means the material is not ductile.

Hence the "brittle/ductile transition". 

Why does it matter?  Because it produces, what, "reduced tensile elongation", "smaller stress-strain curve area", and "reduced impact strength" in polycarbonate, leading to... let's see... sudden failure under compression, sudden failure at notches and corners, and a general drop in what the ref. calls "toughness (https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/Plastic-Materials-in-Cryogenic-Environments)".   

As a pressurized dome?  Just seems like a bad idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 05:38 am
Survive

Here is my calculation of the various domes.

It was a bit more complex than expected, since I needed to convert the external film coefficient into the actual convection coefficient, and then iterate manually  on a continuity formula, where Conduction in glass = Radiation+ external convection.

Anyway.
A 75m radius on Mars gains 16 MWh in a day at 45 degrees north.
For a single pane glass dome and Earth pressure external atmosphere, the loss is 300 MWh per day.
For a single pane glass dome with Martian external pressure, the loss is 73 MWh per day.
For a double pane glass with low emissivity film and a martian pressure air gap, the loss is 7 MWh per day.

So we need the low emissivity film and we need the second glass pane.

Similar results for a plastic film algae growth tunnel. 2mradius 200m long
For a single wall, gain is 750 kWh, loss is 7500 kWh, so perfect as a nuclear reactor cooling system, not so good otherwise.
For a double wall with low E film and a low pressure air gap, the loss is 350 kWh.  So no secondary heating required and the tube in a net energy gain.

These are commuter train time calculations, so there may be errors, take with a grain of salt.  But I think it's probably pretty close to reality.

Thanks for those hard calcs. 

Cross-check:  Setting the dome's single-pane temperature delta to 160 C, under 100 kPa, produces a heat loss roughly consistent with the terrestrial 100 MW flux predicted from R-value.  So that seems right.

Corollary:  That terrestrial heat loss is ~7x your heat loss under 1 kPa, indicating that max heat loss during the martian winter night might be 10-20 MW.  With your several improvements, the max heat loss is cut to about 800 kW.

Energy:  Finding the energy to heat your dome could be challenging, even with the improvements.  Your daily 7 MWh loss = 25 billion J.  And a 100 ton flow battery can deliver, I think, maybe 70 billion J of electrical heating. 

That's 3 nights. 

How to survive the winter?

(http://www.aljazeera.com/mritems/Images/2015/11/30/a3a17370d15d460f805e1150476246a9_18.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/03/2016 08:45 am
Random thoughts:

A solar tower type set up could generate electricity, and the waste heat from this could also go to heating your dome. This reminds me of an idea I had: to dig into one wall of an east-west canion and having reflectors on the far wall. In that case I thought the reflectors could also be solar panels, only reflecting light most suitable for photosynthesis into the greenhouses to avoid baking them.

Solar panels also have the advantage of working better during dust storms.

The other thought was just that it is probably a lot easier to create a true vacuum layer on Mars? Would that help? Or is most of the leakage in visible light? If that was the case you might want to cover the the dome in white on cold days.. like Christmas :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 10:40 am
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

The base is mostly underground, with a pair of exterior domes and a large spaceport, as well as a solar power field.  Not illustrated are large underground stores (artificial caverns) of oxygen, methane, nitrogen and water.  At least enough for two years of survival.  Would these be liquid?  Probably, with a bit of insulation.
If there is someone who participated in the food on Mars thread, was there a conclusion?  Algae tubes or underground caves with artificial lighting?

As far as winter goes, there's probably an optimum latitude where winters are less extreme, Mars tropics, if you will.  We need a spot that isn't too cold in winter, and not so hot that all ice has sublimated.  I believe there are quite a few though. 
The typical average solar gain is twice the night loss in the calculations.  So most of the time the dome needs cooling, not heating.  In winter, you might simply close down the domes and live in the underground sections.  Open again in spring, as soon as the domes have positive gain.  As we do on Earth with greenhouses.

Carbontate deposits have been found on Mars, Wikipedia: Carbonates on Mars.  Perhaps that might make it easier to fabricate certain plastics.  There's probably a geology thread on the Forum, somewhere.

In the double pane glass dome, the losses are mostly radiative.  A simple solution is triple pane glass (available on Earth, after all) , but you do start reducing the gain.  Low e films are not perfectly clear on the non mirror side.  Another would be internal movable curtains, used in most greenhouses in Canada, BTW.

The mathematics of Wikipedia: multilayer insulation can be used to analyse the dome' insulation

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/03/2016 11:33 am
Toughing It Out

Isn't the brittle transition temperature more critical?
...

Brittle does not mean "weak", it simply means the material is not ductile.

Hence the "brittle/ductile transition". 

Why does it matter?  Because it produces, what, "reduced tensile elongation", "smaller stress-strain curve area", and "reduced impact strength" in polycarbonate, leading to... let's see... sudden failure under compression, sudden failure at notches and corners, and a general drop in what the ref. calls "toughness (https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/Plastic-Materials-in-Cryogenic-Environments)".   

As a pressurized dome?  Just seems like a bad idea.
Simply not a concern with multiple panes. Just like with Shuttle, the load bearing pane is different than the outer refractory pane. I just don't see the issue, here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/03/2016 11:51 am
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/03/2016 11:56 am
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?
SpaceX people, hopefully with the help of others. In ITSes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 11/03/2016 12:08 pm
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

Exactly the same questions apply to any proposed habitat on Mars. And many of the proposed ones are more complicated that this!
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/03/2016 12:18 pm
...
Why does it matter?  Because it produces, what, "reduced tensile elongation", "smaller stress-strain curve area", and "reduced impact strength" in polycarbonate, leading to... let's see... sudden failure under compression, sudden failure at notches and corners, and a general drop in what the ref. calls "toughness (https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/Plastic-Materials-in-Cryogenic-Environments)".   

As a pressurized dome?  Just seems like a bad idea.

Not really. Reduced toughness only matters under impact loads, and the external walls of a hab shouldn't normally see any impact loads. Meteorites energetic enough to break a several centimeter thick polycarbonate panel are quite rare as the atmosphere effectively slows small ones. Flying debris from a spaceship landing/takeoff/RUD is more likely, but should not be a common occurrence (if it is, you have bigger problems).

Designing a pane and frame structure that can survive losing several panes is not that difficult... it's not like losing a few panes will cause the whole habitat to explode. A large dome would take hours to depressurize even if a couple panels are completely gone, giving time to plug even a large leak.

And as Chris notes above, a multi-layer construction is likely for thermal regulation. The outer panes would be designed for thermal regulation and abrasion resistance (probably glass) , and the inner layers would be designed for structure and pressure containment and puncture resistance (probably polycarbonate or a similar polymer). That way the structural members are always at or near inside temperature and can stop anything that comes through the thermal layer.
Title: Re: Envisioning Amazing Martian Habitats
Post by: bregallad on 11/03/2016 12:56 pm
About a decade ago I worked with some ~40" glasses-free 3D 1080p plasma displays that shifted perspective 9 times as you walked around them.  They required(and displayed) 18 video inputs.  They worked pretty well, for any number of people from differing viewing geometries, simultaneously.

Every time I read about the importance of windows in the ITS and transparent elements of habs being psychologically important on this site, I think back to those.

A voice of sanity.
Millions of people spend weeks or even months on end with no outside view through windows. Tens, maybe hundreds of millions of people have rather crappy scene viewable from their home/office windows (such as a wall of the next building filling the entire view).
This is an invented problem.

I don't think it is an invented problem. There's a big difference between not having a great view/not going outside, and knowing you can't EVER go outside. The psychological aspects of this cannot be ignored.

But one technology I think could help with this, in small and large underground bases:

https://www.youtube.com/watch?v=aJ4TJ4-kkDw

If you combine these skylights in a large underground dome with plants etc. it could look and feel like outside without the complexity of an actual glass dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/03/2016 01:13 pm
You can go outside on Mars just as much as you can in Minnesota in January. In both cases, if you're not properly dressed, you'll be dead in minutes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: bregallad on 11/03/2016 01:21 pm
You can go outside on Mars just as much as you can in Minnesota in January. In both cases, if you're not properly dressed, you'll be dead in minutes.

Imagine this: You live in a tunnel with no windows. It's small, and ugly (designed for utility not style, like nuclear bunkers if you've ever seen them). You can't go outside unless you take at least one hour to put on a suit, go through stringent procedures, and then there is still the risk of something going wrong at all times, and that could be fatal.

Now imagine living in Minnesota. Were you have big windows, where you can see the outside. You can run outside in your shorts if you really want to. If you do end up outside with little clothes you can seek help. You have a heated vehicle that can take you to see other people... etc.

There is no equivalency here. It is a completely different situation, let's not pretend it is not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 01:24 pm
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.  And they didn't build a 10 000 people complex but a 1 billion $ mine infrastructure, including removal of the overburden and a crushing facility for 40 000 tonnes of ore per day, and housing for 400-1000 permanent workers.  Then then took the construction camps apart.

The cost of a 400 people camp on Earth is about 250 000$ per unit so about 100 million dollars.  My wild guess would then be about 2 billion dollars, with infrastructure, excluding transportation costs.  so about 200 000 dollars per colonist.  Not houses, but small apartments.

Transportation and power costs are wildly dependant on the possibilities of in situ resource development.  I will refrain from over speculating on that subject, if you will allow. Constructive suggestion would be nice, however ;-)  I'm certainly willing to improve the proposed arrangements.

Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/03/2016 02:22 pm
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.  And they didn't build a 10 000 people complex but a 1 billion $ mine infrastructure, including removal of the overburden and a crushing facility for 40 000 tonnes of ore per day, and housing for 400-1000 permanent workers.  Then then took the construction camps apart.

The cost of a 400 people camp on Earth is about 250 000$ per unit so about 100 million dollars.  My wild guess would then be about 2 billion dollars, with infrastructure, excluding transportation costs.  so about 200 000 dollars per colonist.  Not houses, but small apartments.

Transportation and power costs are wildly dependant on the possibilities of in situ resource development.  I will refrain from over speculating on that subject, if you will allow. Constructive suggestion would be nice, however ;-)  I'm certainly willing to improve the proposed arrangements.

As there's likely to be some injuries or worse, plus NASA would want to send along a few scientists, and construction in a near vacuum is a bit different, you'd probably need to bump up the personnel count by about at least 25%, but overall, not an entirely unreasonable estimate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 02:59 pm

As there's likely to be some injuries or worse, plus NASA would want to send along a few scientists, and construction in a near vacuum is a bit different, you'd probably need to bump up the personnel count by about at least 25%, but overall, not an entirely unreasonable estimate.
Injuries are rarer than they were.  The projects I was involved with all had 0 loss of life.  There would have been hell to pay if someone had died from work related injuries.  Probably going to kill a few robots, though.  and depending on colonist involvement you might have some deaths from enthusiastic amateurs.
I'm willing to admit 25% more at this point, no problem.  you guess is a good as mine.  Likely better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 08:39 pm
Connery & Vacuum Exposure

A large dome would take hours to depressurize even if a couple panels are completely gone, giving time to plug even a large leak.

Actually, if lamontagne's 150 m dome lost one brittle panel it would depressurize to the Armstrong Limit in ~2 minutes (http://www.geoffreylandis.com/higgins.html).  (If 60 kPa dome and 35 m2 panel.) 

Approx. illustration, with Connery:

https://www.youtube.com/watch?v=vyzGCAJngkc

Golf clap for Connery.

You might be thinking of small constrained punctures, more typical of tear-resistant ETFE foil, for example.  Tear resistance is an important property of ETFE, but ETFE foil lacks the optical excellence of glass. 

Question:  Are there any cryogenic foils that feature both high tear resistance and also glass-quality transmission, haze and clarity (http://www.byk.com/fileadmin/byk/support/instruments/theory/appearance/en/Intro_Transparency.pdf) (ASTM D1003 test)?  Such a foil, if it existed, would have many potential uses in a Mars hab.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 10:11 pm

Actually, if lamontagne's 150 m dome lost one brittle panel it would depressurize to the Armstrong Limit in ~2 minutes (http://www.geoffreylandis.com/higgins.html).  (If 60 kPa dome and 35 m2 panel.) 


Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Anyway, here is a handy spreadsheet with a hole and pressure drop calculator.  You can size at will.
For a 1m pane, the pressure drop would be 60% after 30 minutes, down to 30 kPa.  Severe but manageable IMHO.

And here is a view of the base without the ground.  I've added a fresh water and waste water caverns, a liquid oxygen cavern, a nitrogen cavern and a methane cavern.  The nitrogen is arbitrarily sized for 5 refills of the habitat.



Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/03/2016 10:20 pm
Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Just as sized in your illustration, at 150 m scale.  But think big, and do try to scale the engineering of elements as best you can.  This is after all a thread for amazing things!  (Also bending force is, I think, typically concentrated in the frame, not the panes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/03/2016 10:34 pm
Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Just as sized in your illustration, at 150 m scale.  But think big, and do try to scale the engineering of elements as best you can.  This is after all a thread for amazing things!
Sorry to have mislead you.  The illustration was just nominal and indicative. Concept art, not engineering drawings.  Making all the little windows would take too much time to render,  so I made them bigger.  Just imagine them at a size you feel is reasonable.  Personally, that's 1 m2 max.  35 m2 will get all the ''tv screen are more practical and just as pretty as windows'' people onto my back, I'm afraid ;-)
I haven't illustrated a true geodesic dome either, just in case.  It's more of a Victorian greenhouse dome. It would take me days to build a model of a geodesic dome at this scale.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/03/2016 11:10 pm
The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.

Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/04/2016 12:00 am
Here are a few overall images of a Martian base.
Hope you all find it Amazing ;-)

Who builds this impressive facility? Where did they live while they were building it? If a similar facility was built on Earth what would it cost? How long would it take to complete?

Back of the envelope cost comparisons of earthworks vs. "marsworks" will probably give wrong answers. There are (at least) two reasons for this.

The first reason is that on Mars, opportunity costs are relative to your opportunities on Mars, and the costs to bring hardware over have already been sunk and are irrelevant. So the opportunity cost exercise you'd have to do is: for the same time and/or wear and tear of the capital piece of equipment, how much pressurized volume can I create on Mars, and what is the quality of that volume in terms of weighted metrics that I care about? You rank these projects, and the project that has the lowest time or wear and tear cost per (quality-adjusted) unit pressurized volume is the project with the lowest Martian opportunity cost.

The second reason is in some ways a detail aspect of the first one. To make valid inferences for Mars costs from cost information that applies for analog processes on Earth, one must first decompose the Earth cost function to a high level of detail and then a cost function for Mars should be constructed. But before constructing the Martian cost function (in terms of time, wear and tear, etc.) all the explicit AND IMPLICIT assumptions for each line item should be carefully considered to see if the assumptions that apply on Earth also apply to your digging environment on Mars. Once you are sure you have identified and tested all assumptions, then and only then you can build the Martian cost function and plug it into your opportunity cost analysis above.

So the answer to your question, of what it would cost on Earth and how long it would take to complete a similar project here, is that how much it costs on Earth has little bearing to the opportunity costs on Mars. Or to put it another way that is relevant to this thread, the more amazing and the bigger the habitat that can be constructed with a given set of equipment, then all other things being equal, the lower the Martian opportunity cost of building it!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/04/2016 12:11 am
It's almost impossible to accurately estimate the cost of a large Mars project like we're discussing here. Just take logistics. If you took a NASA approach of assuming expendable architecture with half a dozen totally different vehicle designs to achieve the goal with half a dozen new technologies (NTR, etc), the cost would be about 4 orders of magnitude greater for a given large capability than SpaceX's approach (which some are skeptical of).

As such, there's no chance of accurately comparing Mars vs Earth costs, except to say Mars will cost more. How much more could easily vary by a factor of a thousand depending on who you ask.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/04/2016 12:17 am
Agreed, it's almost impossible. Notice how I carefully and completely avoided reference to dollars or any units of Earth money. That was not by accident, on Mars the only costs are opportunity costs and the only way you can measure those is relative to the opportunities you pass up to do the activity whose cost is in question.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/04/2016 03:48 am
Pharaohs of Mars

I've added a fresh water and waste water caverns, a liquid oxygen cavern, a nitrogen cavern and a methane cavern.

These tunnel-bored storage caverns would be amazing.  Like the chambers of the pyramids!   

But, why build them?   

Oli (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603731#msg1603731) suggested the scale of the tunnel-boring challenge, and I tend to think he understated.  One would tunnel only when necessary; when other construction methods are clearly inferior. 

So, these storage caverns:

Caverns in bedrock can hold pressurized gases, but a cryogenic distillery can liquefy gases to increase density hundreds or thousands of times, for storage efficiency.  One such plant is required for CH4 and O2 propellant anyway.  It could just as easily liquefy nitrogen.  Argon too, if, say, you wanted to harvest and store propellant for solar electric propulsion at Mars.

Assuming your selected site had appreciable ice and salts, and some topographic depression, you could make a simple brine pool.  Melt, mix, dump.  Salts lower freezing point and raise boiling point, so that the pool remains liquid at depth over a wide temperature range.  Surface freezing increases salt concentration, depressing the brine's freezing point further.

Place lightweight, cryogenic, insulated inflatables in the brine.  Attach the cryogenic spigots, and fill the inflatables with liquid gases.  The gases are now stored.  Freshwater in a separate brine pool, with heated inflatable.  Wastewater, likewise.  Storage caverns are thereby rendered unnecessary.

Such a scheme might be implemented over a martian summer, saving years of cavern construction work, and the thousands of cargo tons and billions of dollars associated.

Or, why not?

(http://cdn.history.com/sites/2/2014/01/grand-gallery-khufu-P.jpeg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 05:15 am
The facility is built by colonists and contract workers with a lot of robotic help.
This is probably a 4 step process:

1- The first landers build a small initial construction camp, for about 15-20 people, using prefab materials they brought, over a few weeks.
2- The 15 then take 2 years to build a slightly larger construction camp, good for 100 people.
3- 100 people take 2 years to build part of the larger cave, for 800 people. 
4- 800 people take 2 years to build the facility, good for 10 000 people.
So about six years.

These numbers are not entirely taken from a hat.  I have participated in the construction on three gold and iron mines in remote parts of Canada that used exactly the same geometric growth, except that things went much faster, in groups of six months.

Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 05:28 am

Assuming your selected site had appreciable ice and salts, and some topographic depression, you could make a simple brine pool.  Melt, mix, dump.  Salts lower freezing point and raise boiling point, so that the pool remains liquid at depth over a wide temperature range.  Surface freezing increases salt concentration, depressing the brine's freezing point further.

Place lightweight, cryogenic, insulated inflatables in the brine.  Attach the cryogenic spigots, and fill the inflatables with liquid gases.  The gases are now stored.  Freshwater in a separate brine pool, with heated inflatable.  Wastewater, likewise.  Storage caverns are thereby rendered unnecessary.

Such a scheme might be implemented over a martian summer, saving years of cavern construction work, and the thousands of cargo tons and billions of dollars associated.

Or, why not?

The storage caverns shown are for liquefied gases.  They are, as you say, thousands of times smaller and do not require many resources beyond conventional mining equipment.
So we agree!

I have no opinion between cut and cover and mining. Both might produce similar results.  The caves illustrated do not need tunnel boring machines, by the way, they are on grade and can be built using drill and blast, if nitrates are cheap enough to produce, or mechanical grinding.  Adequate terrains might produce interesting cut and cover possibilities.  In the end though, they would be very similar to what I'm showing, no?

Brine covered tanks are very interesting.  I expect there are no particular problems with large cryogenic temperature flexible membranes? so it might indeed be a more economical solution.  There would be some additional work required for methane and nitrogen though, since these are quite a bit less dense than water.  Actually, water is less dense than brine, so some form of anchoring or most likely ballasting would be required.  Adding some complexity.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 06:41 am
A large underground excavated cave, for 5000 people.
Perhaps a little ambitious :-) 
400m long and 100m in diameter
80 000 m2 of food production in the lower levels, a  16 000 m2 green park in the middle.
about 25 000 m2 of apartments.  A bit tight, at 50ft only per room. I should add some built area, I think, work and common areas.
The cavern is built rapidly; the apartments are added much more slowly, as population arrives.

Anyone has Amazing architectural styles to suggest?


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 06:59 am
A FIFA sized football field.

A remarkable waste of space, I expect.  But what might be the requirements for sport facilities in a Martian habitat, a few years down the line?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/04/2016 07:04 am
Mining Methods

I have no opinion between cut and cover and mining. Both might produce similar results.  The caves illustrated do not need tunnel boring machines, by the way, they are on grade and can be built using drill and blast, if nitrates are cheap enough to produce, or mechanical grinding.  Adequate terrains might produce interesting cut and cover possibilities.  In the end though, they would be very similar to what I'm showing, no?

I wouldn't know the pros/cons of tunnel boring vs. drill-and-blast, but neither sounds like an easy time on Mars.  :)  Boring is direct-electrical mechanism, which should be most efficient, but limited in hours of operation, right? 

And did you have some thought on ISRU nitrates or other explosive options for drill-and-blast?  There are a lot of potential redox pairs in the notional facilities:  even the greenhouse could potentially supply.  Thinking specifically of greenhouse nitrate production.  Poster sghill owns an electrochemical fertilizer company with equipment that makes nitrate at ambient air pressure, more efficiently than the standard high-pressure Ostwald process.  It could conceivably be adapted as a greenhouse cottage industry: in-house fertilizer production, with a mining application in your scheme.  Posts 1 (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1579832#msg1579832) 2 (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1579934#msg1579934) 3 (http://forum.nasaspaceflight.com/index.php?topic=35877.msg1583273#msg1583273). 

Why the nitrate preference?  For ease of transport, in ammonium nitrate solid, or some other advantage? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/04/2016 01:00 pm
Liquid oxygen and carbon monoxide mix would be a potent and cheap explosive on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/04/2016 04:03 pm
Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Earth.

Well, you pass the honesty test. :) But I have a hard time envisioning any terrestrial entity willing and able to support hundreds (to say nothing of 10,000) people on Mars for years on end with no payback in prospect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/04/2016 04:22 pm
Great, but surely that's just the tip of the iceberg? On earth, such projects are only viable because we have the resources of an advanced industrial society to draw from. What is filling this role on Mars in your project?
Earth.

Well, you pass the honesty test. :) But I have a hard time envisioning any terrestrial entity willing and able to support hundreds (to say nothing of 10,000) people on Mars for years on end with no payback in prospect.

Depending on how much money we're talking about, a foundation setup by Musk and other billionaires could do it. Not everything has to show a profit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 08:05 pm
Perhaps room and pillar mining would produce more area for less cost than the large vaults I've been illustrating?
This machine is optimized for coal, but there must be versions for harder rock?
Creates 4m high caves, continuous operation, much lighter than a tunnel boring machine, but optimized for much softer rock.  Mostly automatic. 610 kW total machine power.

Is there soft rock on Mars?


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/04/2016 08:27 pm
This is how large room and pillar construction can get:

Subtropolis in Kansas city

https://www.youtube.com/watch?v=3DJ4VjIRM24
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/04/2016 08:44 pm
Anyone has Amazing architectural styles to suggest?

I like the principles of city design as described at http://www.carfree.com/ The site is looking kinda dated now but if you take the idea of the districts and apply them to individual cavens then there is alot that could be applied to Mars habitats.

Worth a look I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/04/2016 09:18 pm
Perhaps room and pillar mining would produce more area for less cost than the large vaults I've been illustrating?
This machine is optimized for coal, but there must be versions for harder rock?
Creates 4m high caves, continuous operation, much lighter than a tunnel boring machine, but optimized for much softer rock.  Mostly automatic. 610 kW total machine power.

Is there soft rock on Mars?

Look up Sandvik Roadheader.  Amazing machines. Much more versatile than a TBM for hab cavern excavations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/05/2016 01:55 am
Boring Basalt

Perhaps room and pillar mining would produce more area for less cost than the large vaults I've been illustrating?
This machine is optimized for coal, but there must be versions for harder rock?
Creates 4m high caves, continuous operation, much lighter than a tunnel boring machine, but optimized for much softer rock.  Mostly automatic. 610 kW total machine power.

Is there soft rock on Mars?

Look up Sandvik Roadheader.  Amazing machines. Much more versatile than a TBM for hab cavern excavations.

Pretty amazing.  Here's the big Sandvik MT720 in action.

https://www.youtube.com/watch?v=QyE5kAothQ4

I see the MT720 is designed for rock "exceeding 120 MPa uniaxial compressive strength" (UCS).  That sounds like a lot, but igneous rock can have even higher UCS.  In one tunnel boring case study (http://www.sciencedirect.com/science/article/pii/S1674775513001224), basalt in the Deccan traps had a max UCS of 143.  Would that pose problems for the MT720?   

In the study's particular basaltic tunnel, a gripper TBM was used.  For the purpose of opening large crewed facilities in igneous rock, I think gripper TBMs on the scale of these Herrenknecht TBMs might be required.  Look at the scale and complexity, not only of these TBMs, but of the plants supporting them.  Adapting all that to martian conditions, would be, like... whew.

https://www.youtube.com/watch?v=quu2r5vs0hA
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/06/2016 11:36 am
A large underground excavated cave, for 5000 people.
Perhaps a little ambitious :-) 
400m long and 100m in diameter
80 000 m2 of food production in the lower levels, a  16 000 m2 green park in the middle.
about 25 000 m2 of apartments.  A bit tight, at 50ft only per room. I should add some built area, I think, work and common areas.
The cavern is built rapidly; the apartments are added much more slowly, as population arrives.

Anyone has Amazing architectural styles to suggest?


Venice and Amsterdam mansions on either side of canals, including the canals, boats and gondolas.

Also the magnificent covered galleries in Milan, Vittorio Emmanuele I think? from upthread..

Renaissance-era facades and interiors from Europe.

Each neighborhood to have one style and a name to match - "Little Venice", "Little Milan" etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/06/2016 08:22 pm
The galleries on Eros in the sci-fi series "The Expanse" are pretty cool (fake sky, of course)...

(http://sfmag.hu/wp-content/uploads/2016/02/TheExpanse_gallery1.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/06/2016 11:28 pm
Goodness me, why should I use such large panels?  And how could I build them?  I was thinking of window panes, more of less 1 or 2 m2.  The bending moment on something so large would be horrendous!
Perhaps it's a mistype? 
Just as sized in your illustration, at 150 m scale.  But think big, and do try to scale the engineering of elements as best you can.  This is after all a thread for amazing things!  (Also bending force is, I think, typically concentrated in the frame, not the panes.)

For a spherical dome dominated by internal pressure loads there is almost pure tension and no bending anywhere in the structure. The panes should be small enough that losing a few doesn't compromise the structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/07/2016 12:05 pm
Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power
Electrical power, 2400V. 350 kW.
9mx6m tunnel cross section
Remotely operated, automatic profiling of cut.
50 tonnes mass,shipped unassembled
Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

I would expect this to be shipped with the first large group of colonists.


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/07/2016 01:21 pm
Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power

Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

And with planetary team colors no less.  But it can't fly til it's certified for basalt.  At 143+ MPa UCS (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1606657#msg1606657), there's a considerable gap between Roadheader spec and your excavation need.  Actually, it looks as though Roadheaders excavate around basalt, not through it:  e.g., Project Hobson (https://books.google.com/books?id=NAu_us9r9fkC&pg=PA452&lpg=PA452&dq=%22project+hobson%22+road+cutter&source=bl&ots=3eop83F3cy&sig=Y8KZvwbb90JcKoHSk8itDudx6Y4&hl=en&sa=X&ved=0ahUKEwiEgKKx6pbQAhXIVyYKHSgMD5wQ6AEIJDAB#v=onepage&q=%22project%20hobson%22%20road%20cutter&f=false).  Any info on Roadheaders working within basalt?

Ref.  Geological limits in Roadheader excavation - four case studies (http://www.plinninger.de/images/pdfs/1998_iaeg_vancouver.pdf)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/07/2016 01:34 pm
Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power

Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

And with planetary team colors no less.  But it can't fly til it's certified for basalt.  At 143+ MPa UCS (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1606657#msg1606657), there's a considerable gap between Roadheader spec and your excavation need.  Actually, it looks as though Roadheaders excavate around basalt, not through it:  e.g., Project Hobson (https://books.google.com/books?id=NAu_us9r9fkC&pg=PA452&lpg=PA452&dq=%22project+hobson%22+road+cutter&source=bl&ots=3eop83F3cy&sig=Y8KZvwbb90JcKoHSk8itDudx6Y4&hl=en&sa=X&ved=0ahUKEwiEgKKx6pbQAhXIVyYKHSgMD5wQ6AEIJDAB#v=onepage&q=%22project%20hobson%22%20road%20cutter&f=false).  Any info on Roadheaders working within basalt?

Ref.  Geological limits in Roadheader excavation - four case studies (http://www.plinninger.de/images/pdfs/1998_iaeg_vancouver.pdf)
Well, let's find a nice area of sandstone, or something else both soft enough and strong enough.  Mars has varied terrain, we don't need to find the hardest one, but the most appropriate and easiest one.
Here is an outcropping of sandstone on Mars, and a link to a bit of Martian geology.  Could dig into that?

http://geology.com/stories/13/rocks-on-mars/


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/07/2016 05:52 pm
Sharp Cut

Behold!  The Sandvik Roadheader, Mars Edition.

350 m3 per day of continuous digging power

Can be used to dig tunnels, chambers, ramps and alcoves in rock up to 100 MPa in compression.

And with planetary team colors no less.  But it can't fly til it's certified for basalt.  At 143+ MPa UCS (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1606657#msg1606657), there's a considerable gap between Roadheader spec and your excavation need.  Actually, it looks as though Roadheaders excavate around basalt, not through it:  e.g., Project Hobson (https://books.google.com/books?id=NAu_us9r9fkC&pg=PA452&lpg=PA452&dq=%22project+hobson%22+road+cutter&source=bl&ots=3eop83F3cy&sig=Y8KZvwbb90JcKoHSk8itDudx6Y4&hl=en&sa=X&ved=0ahUKEwiEgKKx6pbQAhXIVyYKHSgMD5wQ6AEIJDAB#v=onepage&q=%22project%20hobson%22%20road%20cutter&f=false).  Any info on Roadheaders working within basalt?

Ref.  Geological limits in Roadheader excavation - four case studies (http://www.plinninger.de/images/pdfs/1998_iaeg_vancouver.pdf)
Well, let's find a nice area of sandstone, or something else both soft enough and strong enough.  Mars has varied terrain, we don't need to find the hardest one, but the most appropriate and easiest one.
Here is an outcropping of sandstone on Mars, and a link to a bit of Martian geology.  Could dig into that?

http://geology.com/stories/13/rocks-on-mars/

An interesting exercise, no matter how you cut it.  :) 

Speaking of Gale Crater, how about a hypothetical?  Given what's known or suspected of Mt. Sharp stratigraphy (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf), where might you park that Roadheader to start a Mt. Sharp cut?

(https://upload.wikimedia.org/wikipedia/commons/thumb/b/b0/PIA19912-MarsCuriosityRover-MountSharp-20151002.jpg/800px-PIA19912-MarsCuriosityRover-MountSharp-20151002.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/07/2016 07:21 pm

Speaking of Gale Crater, how about a hypothetical?  Given what's known or suspected of Mt. Sharp stratigraphy (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf), where might you park that Roadheader to start a Mt. Sharp cut?

Perhaps in the sandstone layer, if it is thick enough?  Gypsum is also possible, if I understand the mineralogy, but that might be too fragile.  Gale Crater is perhaps a little close to the equator for important amounts of water?  Perhaps a similar crater, but closer to one of the possible glaciers?  A little to the north?   What would be good is a combination of a nice thick eroded sandstone formation, close to a level floor area and an important glacier.  I take it I can continue designing a base around caves built by a machine such as the roadheader?
Next step: a rolling crane, a shed, a low mining truck and some early habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 11/07/2016 08:51 pm
The significant point about these geodesic domes are that they are constructed from large quantities of small generic parts. Additionally such parts would be candidates for 3D printers to produce from local materials (such as glass from silicon readily available). It would be interesting to have a 3D printer that printed glass panes of a specific shape with edges that have lips to help with sealing. Plus the glass panes or opaque glass panes for the lower levels would represent the major portion of the weight of the "dome".

Unfortunately the structural elements and panes are individually designed to create a dome of a specific diameter even though there are a large number of identical elements they are still specific to a specific dome size.

The answer would be a set of 3D printers that can then print the structural and panes from feed-stock either shipped to Mars or locally made such that the domes are designed at the location based on the conditions found, such as using a specific crater as a starting point for siting the dome but only once the crater has been explored. This method of using shipped feed-stock vs shipping finished elements makes it easier to ship since feed-stock is very compact and has high mass to volume vs end product manufactured elements.

This method has many advantages in that it is from the beginning a drive to make it point to use local resources as much as possible as early as possible. As feed-stock becomes available from local sources that becomes that much less of that feed-stock need from earth which can be swapped for the other feed-stocks that increases the overall increase in the amount of domes created for a given shipping amount.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/07/2016 09:07 pm
Gypsum is a highly hydrated mineral so if you have gypsum you have water. And the energy needed to extract water from gypsum is about 1.5-2 orders of magnitude less than required to electrolyze the water for propellant usage (i.e. Methane--once combined with CO2--and oxygen), and that will be the primary usage of water for a while because you need 2000 tons of propellant per ITS.

So I don't think that being near the equator is a bad thing since you still have access to plenty of water and you have more moderate temperatures and access to better sunlight and an easier time landing and especially launching.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/07/2016 09:08 pm
Hellas basin.
7000m below datum.
Glaciers reported 250m thick.
Don't know about the rocks.
Southern Hemisphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/07/2016 09:13 pm
Hellas is reportedly pretty dusty and is pretty far south. Both are bad if you're reliant on solar power. Melas Chasma in Valles Marineris is -5km still, right on the equator, has lots of hydrated minerals (and even lineae) and a fantastic view.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/07/2016 09:18 pm
Any glaciers?
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 11/08/2016 01:15 am
Hellas is reportedly pretty dusty and is pretty far south. Both are bad if you're reliant on solar power. Melas Chasma in Valles Marineris is -5km still, right on the equator, has lots of hydrated minerals (and even lineae) and a fantastic view.

Plus lots of nooks & crannies to isolate a landing field and a nuclear plant from residences.
Burrow into the many hillsides & cliff sides for heavily shielded colonial homes.
Just check for rockslides etc. first
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 01:43 am
The base domes with a tunnel digger and rolling crane set up in the foreground.
The crane is inside a barely visible plastic dome, that has a low e coating on the inside.  There are radiant heaters on the crane structure.
This allows the roadheader to be made from standard materials, as  it never sees very cold temperatures, since Martian cooling is mainly radiative, not convective. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 02:52 am
Raw and finished tunnel.
10m wide x 7m high
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 02:57 am
People are supposed to be living in the glass domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 03:08 am
People are supposed to be living in the glass domes.
It's just one of the possibilities.  If the glass domes prove too expensive compared to tunnels there will be a mix, with the domes being more of a prestige area, perhaps.  Or people sleeping in the tunnels, and doing daily activities in the domes.   Or if the radiation dosage in the domes at full time gests too high.
The strict glass domes and industrial tunnels is another thread, this one is more free, IMHO.  As long as it's amazing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 03:24 am
The significant point about these geodesic domes are that they are constructed from large quantities of small generic parts. Additionally such parts would be candidates for 3D printers to produce from local materials (such as glass from silicon readily available). It would be interesting to have a 3D printer that printed glass panes of a specific shape with edges that have lips to help with sealing. Plus the glass panes or opaque glass panes for the lower levels would represent the major portion of the weight of the "dome".

Unfortunately the structural elements and panes are individually designed to create a dome of a specific diameter even though there are a large number of identical elements they are still specific to a specific dome size.

The answer would be a set of 3D printers that can then print the structural and panes from feed-stock either shipped to Mars or locally made such that the domes are designed at the location based on the conditions found, such as using a specific crater as a starting point for siting the dome but only once the crater has been explored. This method of using shipped feed-stock vs shipping finished elements makes it easier to ship since feed-stock is very compact and has high mass to volume vs end product manufactured elements.

This method has many advantages in that it is from the beginning a drive to make it point to use local resources as much as possible as early as possible. As feed-stock becomes available from local sources that becomes that much less of that feed-stock need from earth which can be swapped for the other feed-stocks that increases the overall increase in the amount of domes created for a given shipping amount.
If the domes are made from tubes and connectors, we might only 3D print the connectors and cut the tubes to length.  Probably faster.
It might also be possible to have standard polygonal (or triangular) glass shapes and grind these to fit, following the design of the required pattern to adapt to local conditions.
The earlier domes might be fixed and relatively small.
It would be important to analyse the structure so the failure of a window does not induce too much torsion in the framing, or we might get a zipper effect and a cascade of failures.  I don't expect the glass to carry any tension, that will be the role of the geodesic members.  The glass would only be in bending, and hyperstatic bending at that, so probably not too severe if we keep the dimensions of the panes down to about 1m.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 04:57 am
Sharp Cut


Speaking of Gale Crater, how about a hypothetical?  Given what's known or suspected of Mt. Sharp stratigraphy (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf), where might you park that Roadheader to start a Mt. Sharp cut?


I take it I can continue designing a base around caves built by a machine such as the roadheader?

You asking permission?  :)

Mt. Sharp is our one case study:  the first martian sandstone formation to get a proper in situ geological analysis (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf).  I'd think we could get a lot of mileage out of that, if we wanted to:  some exercise of tunnel-hab imagination.

What to look for?  Thick units, sure.  Sandstone or rock of similar hardness.  Good dips I suppose, for ease of excavation.  Low seepage.  High uniformity.  And?

And... Mars starts throwing curveballs, as always. 

In this case I'm thinking about toxins.  On Earth, sandstone is benign.  But sand doesn't accumulate perchlorates on Earth.  Where martian sandstone has aeolian origin, the original windblown dunes could have accumulated perchlorate salts.  Low-temperature compression and cementation would convert dunes to sandstone, but leaving perchlorates unaltered, within the final stone. 

Dig into that stone, pressurize chambers, turn on the heater -- and the humidifier.  What happens to the exposed perchlorates?

Or do you see better options in the Mt. Sharp stratigraphy?

(https://visitidaho.org/content/uploads/2015/10/st-anthony-sand-dunes-.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 04:59 am
Exposed perchlorates, when heated in presence of moisture (and ubiquitous iron compounds on Mars) would probably release oxygen and become pretty benign. At least if you did things right. :)

But seriously. Perchlorates are both an energy and oxygen source.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 06:36 am
Perchlorates are both an energy and oxygen source.

This is not a microbial astrobiology thread, Senior Member Robotbeat. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 07:01 am
Perchlorates are both an energy and oxygen source.

This is not a microbial astrobiology thread, Senior Member Robotbeat.
I'm not talking about astrobiology.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/08/2016 12:33 pm
Just being polite ;-)
Reading the study, there are significant episodes of acidic influence on the material in the layers making up the mountain, that is why we have chlorates (although no mention of which chlorates).  When these layers were laid down, millions or even billions of years ago, there were probably no perchlorates around, as it was a humid environment and these would have been unstable.  the perchlorates are probably a "relatively" recent addition, created by the very dry nature of Mars' present atmosphere. So my guess is poisons in the rocks is not an issue; I'll stick to my sandstone layer for the moment. 

Anyone has a suggestion as to the maximum safe size (diameter) of a vault in a sandstone cave?


Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 01:30 pm
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.

So to be clear, the distinction is that the photons travel through a transparent substance to your eyes rather than via an array of CCDs then some circuits and ultimately OLEDs or whatever?  Seems a bit pedantic if it looks the same IMO.  I'm not talking about strapping on a VR headset and "exploring" Mars, I'm talking about replacing windows with like functionality.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2016 02:27 pm
There will always be artifacts if you look hard enough.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 03:01 pm
There will always be artifacts if you look hard enough.

Obviously.  But for the sake of discussion, let's assume that it's a similar pixel density of a high-end phone or tablet display, and the sensor has some optical zoom ability, which you can control at the "window" if you want.

I think it would really be nitpicking at that point, in fact there are more obvious advantages to having the interactive digital window than I care to blab on about, IMO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/08/2016 03:24 pm
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 03:35 pm
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
https://forum.nasaspaceflight.com/index.php?topic=41427.msg1604179#msg1604179
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/08/2016 03:45 pm
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
https://forum.nasaspaceflight.com/index.php?topic=41427.msg1604179#msg1604179

How does it work when several people are in the room?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Req on 11/08/2016 03:48 pm
There will always be artifacts if you look hard enough.

It is not that. It is people know. Also there is the problem with perspective. It does not shift on a screen.
https://forum.nasaspaceflight.com/index.php?topic=41427.msg1604179#msg1604179

How does it work when several people are in the room?

I have no idea how it worked, and I don't remember what the vendor was.  However you can google autostereoscopic displays for more info.  Maybe it had a "subpixel filter?"
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/08/2016 05:03 pm
At some point 3d screens will work just like windows.
It requires huge processing power.
Each pixel needs to be a tv set unto itself.
Each pixel must directionally transmit light in a wide solid arc. Just like a glass windows does.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 08:56 pm
Sharp Cut

Reading the study, there are significant episodes of acidic influence on the material in the layers making up the mountain, that is why we have chlorates (although no mention of which chlorates).  When these layers were laid down, millions or even billions of years ago, there were probably no perchlorates around, as it was a humid environment and these would have been unstable.  the perchlorates are probably a "relatively" recent addition, created by the very dry nature of Mars' present atmosphere. So my guess is poisons in the rocks is not an issue; I'll stick to my sandstone layer for the moment. 

re: perchlorate exposure:

Right, perchlorate accumulation would be a dry effect.  The perchlorates would be anhydrous in sandstone.

Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
 
So, looking at the geological analysis (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf):

It confirms that Mt. Sharp has "an unconformity that separates hydrated from anhydrous rocks".  Above that unconformity are younger rocks that formed from dry windblown deposits.  That's where perchlorates could accumulate.  Below, older rocks; some of which appear to have formed in the presence of water, even within streams and lakes.  Subaqueous sand would have been rinsed clean of perchlorate salts prior to burial.  Net net:  if you're looking for non-toxic hab rock on Mt. Sharp, those strata below the unconformity would be the better prospects.

(subtext:  Amazonian sandstone is suspect hab material, universally, due to the possibility of perchlorate contamination.  At least to my mind.)

Can we glean any other prospecting clues from the geological analysis?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/08/2016 09:52 pm
(...)
Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
(...)

Could this be turned into a process for detoxification of newly excavated spaces?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/08/2016 10:46 pm
(...)
Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
(...)

Could this be turned into a process for detoxification of newly excavated spaces?

Conceivably -- if, say, summoning the evil dead detoxes a graveyard.  :)

(http://cimg.tvgcdn.net/i/2015/10/23/a83e2ea2-e8df-41a2-bc38-78d1ab4e78e4/tumblrml4tklvlux1qgime3o1250.gif)

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/10/2016 04:43 am
Sharp Cut

Reading the study, there are significant episodes of acidic influence on the material in the layers making up the mountain, that is why we have chlorates (although no mention of which chlorates).  When these layers were laid down, millions or even billions of years ago, there were probably no perchlorates around, as it was a humid environment and these would have been unstable.  the perchlorates are probably a "relatively" recent addition, created by the very dry nature of Mars' present atmosphere. So my guess is poisons in the rocks is not an issue; I'll stick to my sandstone layer for the moment. 

re: perchlorate exposure:

Right, perchlorate accumulation would be a dry effect.  The perchlorates would be anhydrous in sandstone.

Adding water vapor indoors, via humidifier, would initiate deliquescence in the exposed anhydrous perchlorate salts.  That would lead to perchlorate mobilization out of the sandstone and into the facility space, potentially exposing the crew to the toxin.  It's not something the EPA would sign off on, I think.
 
So, looking at the geological analysis (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf):

It confirms that Mt. Sharp has "an unconformity that separates hydrated from anhydrous rocks".  Above that unconformity are younger rocks that formed from dry windblown deposits.  That's where perchlorates could accumulate.  Below, older rocks; some of which appear to have formed in the presence of water, even within streams and lakes.  Subaqueous sand would have been rinsed clean of perchlorate salts prior to burial.  Net net:  if you're looking for non-toxic hab rock on Mt. Sharp, those strata below the unconformity would be the better prospects.

(subtext:  Amazonian sandstone is suspect hab material, universally, due to the possibility of perchlorate contamination.  At least to my mind.)

Can we glean any other prospecting clues from the geological analysis?

I think I see a few more clues to guide a hypothetical dig.  Briefly:

Most of the Mt. Sharp rock units are suspect hab material.  High thermal inertia units HTI1 and HTI2 might be dense, but they're young, hence probably of aeolian origin and potentially contaminated with perchlorate salts.   Layered sulfate unit LS contains, well, sulfate, possibly as magnesium sulfate (epsom salt), which would make for very soft, messy rock.  Phyllosilicate unit PhU is a crumbly mudstone. 

Only Murray Formation units MF1 and MF3 look useful.  These basal units appear to be of subaqueous origin, and would therefore be free of perchlorates.  They are also erosion resistant, suggesting some fracture resistance.  Their thermal inertia, and by inference density, is relatively high.  So all-in-all it looks as though MF1 and MF3 are the best units available for a hypothetical Mt. Sharp hab dig. 

Good enough?  Eh, maybe.  Feedback is welcome, etc.

So, hypothetically, where to cut?  Ideally you'd want to cut your entrance into some pre-existing exposure of MF1 or MF3.  You'd also want the tunnel to run up-slope for drainage.  And you'd want to tunnel without detours, with maximum rock uniformity and minimum uncertainty.

Guesstimating from the analysis paper, it looks as though one could attempt these minimal requirements by cutting into the Mt. Sharp contact, starting at the southwest wall of a half-kilometer crater on the edge of unit MF1.  Illustrating with shots from the paper, and Google Mars:

Image:  MtSharpHypothetical1.png

Units:  MF1 medium purple, MF2 light purple, MF3 dark purple.  Access crater at upper right. 

Image:  MtSharpHypothetical2.png

Crater detail.  Removal of loose crater debris would enable tunneling into wall at ~100 m depth. 

Image:  MtSharpHypothetical3.png

Straight-line distance from tunnel entrance to terminus at unit HTI1, 3.4 km.  Line in MF1/MF3 units.

Image:  MtSharpHypothetical4.png

Unit vs. Elevation (units near the hypothetical tunnel line profile; not an exact match).  Units:  MF3 dark purple, MF2 light purple with hematite deposits red, MF1 medium purple, HTI1 brown.  Red line is rise from tunnel entrance to terminus, at steady surface depth of 100 m.  Grade ~3%.



It might be interesting to see how current, "amazing," hab ideas could slot into this hypothetical tunneling site.  Assuming, again hypothetically, that some brine aquifer were discovered and accessed beneath the crater, and hab construction were judged both possible and desirable here, it might be interesting to collectively ballpark, say:

- A design of a dome over the crater
- Optimal layout of underground facilities, to accommodate maybe the first Spartan 300
- Time/energy requirements for the essential Roadheader work 
- Feasible size of some subterranean ("subaresian"?) garden dome

(serving suggestion only, below)  :)

(http://vignette3.wikia.nocookie.net/memoryalpha/images/a/ae/Ocampa_underground.jpg/revision/latest?cb=20061231200127&path-prefix=en)



Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 11/10/2016 03:03 pm
Why are we considering Mt Sharp / Gale Crater as habitat location?
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/10/2016 03:06 pm
Why are we considering Mt Sharp / Gale Crater as habitat location?

I don't think we are. I have not heard of big water deposits at Gale Crater. Formations approached by Curiosity are just used as basis for discussing suitable types of formations for digging habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/10/2016 03:11 pm
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/10/2016 03:15 pm
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/10/2016 03:16 pm
We know the geology.
Just an exercise.

EDIT: in response to why mt. sharp
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/10/2016 03:18 pm
I personally like valles marineris.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/10/2016 04:09 pm
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/10/2016 10:01 pm
Going to the Well

There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.

Not an especially meaningful comparison.  Water is needed, as is propellant.  Each mfg process would be optimized independently. 

Extraction of water from glacier or brine aquifer would be far more energy-efficient than extraction from regolith.  Rough calc:  A gypsum rotary dryer might need 75 kW of power to process 40 tons of regolith with 5% extractable water-mass, in one hour.  Excavation, transport, thaw, material processing and multi-step losses might add another MW.  Net:  ~4 billion J for 2 m3 of water.  Whereas a heater might melt that water from glacier with 700 million J.  Or reverse osmosis might extract the water from brine, using 20 million J. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/10/2016 10:38 pm
There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

Interesting thought to bear in mind: a place with 10% water content in the regolith needs up to five times less energy to extract it than a place with 2%.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/11/2016 12:36 am
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/11/2016 12:49 am
Going to the Well

There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.

Not an especially meaningful comparison.  Water is needed, as is propellant.  Each mfg process would be optimized independently. 
...
No, because if you choose your location based on optimizing water gathering efficiency, it will place you nearer the poles. That compromises the energy production needed for electrolysis since we're reliant on solar power. Additionally, it increases the energy needed to get to orbit, thus requiring more energy still. So you can't optimize them separately, it must be coupled. If getting the water out is significantly less than electrolysis energy (since most of the water will be needed for propellant), then you should optimize for other things, like being close to the equator.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/11/2016 03:59 am
Going to the Well

There's between two and ten percent absorbed water in the regolith anywhere on the planet (think hydrated minerals like gypsum). You can get water anywhere.

But it would take a lot of energy to extract it, unless you have pure minerals like gypsum. No, I believe they will go for glacial water.
Not a lot compared to the energy needed to make that water into propellant. Always look at that relative energy cost.

Not an especially meaningful comparison.  Water is needed, as is propellant.  Each mfg process would be optimized independently. 
...
No, because if you choose your location based on optimizing water gathering efficiency, it will place you nearer the poles. That compromises the energy production needed for electrolysis since we're reliant on solar power. Additionally, it increases the energy needed to get to orbit, thus requiring more energy still. So you can't optimize them separately, it must be coupled. If getting the water out is significantly less than electrolysis energy (since most of the water will be needed for propellant), then you should optimize for other things, like being close to the equator.

Facts first, math second, conclusion third.  Ideally.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/11/2016 04:01 am
I've done the math.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/11/2016 12:24 pm
I've done the math.

If you say so.  And let's remember that Step One, also.  But OT at this point, so somewhere else.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 11/11/2016 01:13 pm
Nat Geo's take on Martian igloos made from regolith
http://www.dailymail.co.uk/sciencetech/article-3924260/Your-future-house-Mars-Martian-home-reveals-life-like-red-planet.html
Home for one person though? and how many airlocks are available?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/11/2016 02:39 pm
Nat Geo's take on Martian igloos made from regolith
http://www.dailymail.co.uk/sciencetech/article-3924260/Your-future-house-Mars-Martian-home-reveals-life-like-red-planet.html
Home for one person though? and how many airlocks are available?

Most of these "Little House on the Martian Prairie" ideas will never be built because they don't fit into any sensible settlement architecture. However we get to hear about these ideas from mass media because they are good mass consumption content for media. Kind of like how some cable science channels are only showing pseudoscience shows nowadays. Very popular but also quite useless other than as light entertainment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/11/2016 02:41 pm
Makin Mars and space in general a part of culture and the public's consciousness is critical to becoming a spacefaring civilization, especially because there's no terribly good economic reason to do so. Make space cool.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 11/11/2016 02:57 pm
Makin Mars and space in general a part of culture and the public's consciousness is critical to becoming a spacefaring civilization, especially because there's no terribly good economic reason to do so. Make space cool.

Exactly as Musk would have put it.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 05:28 pm
Sharp Thistle

OK, taking a shot at the Mt. Sharp hypothetical (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608175#msg1608175), expanding on Lake Matthew dome (http://www.lakematthew.com/wp-content/uploads/2016/06/hab_rough_geometry_v4_1920x901.png) methods:



Image:  MtSharpHypothetical2.png

Crater exposure of sandstone, entry point for tunnel into sandstone unit MF1.



Looking first at only the tunnel's crater entrance, how could that 500 m crater be put to use?

We see that the crater provides a lot of potentially useful space.  With removal of what appears to be mostly sand debris, the 100 m+ deep crater would provide space for a 400 m Lake Matthew-style dome, having pressurized volume of ~6 million m3, all fully protected from surface radiation. 



Image:  MtSharpHypothetical5.png

400 m subaqueous titanium/ETFE dome (white).



Water surfaces inside and outside the dome are marked in blue.  Note the surface just inside the dome perimeter:  this is the notional "moon pool" surface, which allows watergate access to the martian surface outside, sans airlock.

Prior to dome construction, debris sand would be removed via robotics and conveyor, piling outside the crater (purple).   Once the dome cushion modules are constructed and assembled together, the dome enters flotation through incremental addition of water to the moon pool trench, concurrent with increasing dome air pressure.  Water pressure counters air pressure in the trench.  Also concurrently, an open-air 30 m ballast track (green) is filled with sand to 20 m depth.  The fill is sand removed from the crater previously, now returned using the same robotics and conveyor as before.  Dome ribs go into tension, dome perimeter ring goes into compression.

At the end, air pressure reaches 60 kPa, average water depth reaches 5 m, and 180 perimeter rock anchors counter the dome's final net upward force of 800 million N.   Anchors require a mass of ~400 tons: ~170 tons grout, ~230 tons titanium.  The rest of the dome structure requires ~200 tons: ~60 tons ETFE, ~140 tons titanium.  Assuming all alloy is scavenge (from ITS plants, 3D printed into structural members), dome cargo totals ~230 tons.  If construction equipment also utilizes scavenged alloy (e.g., for the conveyor frame), it's likely the entire dome cargo mass, including construction equipment, would be less than the cargo capacity of a single ITS (450 tons).

After the dome enters operation, excavation of the crater floor can continue, and tunneling can begin (brown).  Removal of this debris requires airlocks.  Notionally, zipper truck sinter tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) (red) provide bulk airlocks for debris removal, with cars queued over 200 m within the airlocks.



Heating Problems

Cold sandstone (~-90 C on the coldest nights) presents big heating problems at this very hypothetical Mt. Sharp dome.

For example, anchoring could be a bit tricky.  The grout would have to set for at least a sol, at temperature above 5 C, to preclude any chance of ice formation and weakness.  Maybe that could be done using high-temp heater wire inside the titanium anchor's hollow core, to heat the grout from within.  Also, Mt. Sharp sulfates are a problem there:  Type V Portland cement would likely be required, with fly ash and volcanic ash, to protect the grout from sulfates mobilized in the wetted sandstone. 

Once the dome is in operation, heat conduction into sandstone presents an ongoing problem.  In rough terms:  At -90 C thermal conductivity of the sandstone increases to maybe 5 W/mK.  A 1 m layer of water on that -90 C sandstone would freeze in perhaps a week or so.  That 1 m freeze would present problems, for example, in watergate and moon pool operation.  Melting that 1 m layer would require ~9 trillion J.  If such immense heat energy were available, somewhere, it could be transferred through dome water to the ice.  However the crater's low boiling point (~5 C) would waste that heat:  water above 5 C would boil at the pool surface, quickly losing heat to the atmosphere, instead of the rock-bound ice.

It's a problem for this dome design, yes?



Incidentally, water losses from evaporation and sublimation should be manageable at that site, given hypothetical aquifer.  A 500 m pool, half covered in ice, would lose water at a rate of ~80 m3/hour; a rate readily countered by a hypothetical aquifer pump.

Also, very incidentally, the design looks a bit like a thistle, to my eyes.  So, Thistle Design, then.   :)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/12/2016 05:50 pm
Where is the "Lake Matthew" thread? That'd be a better spot to discuss this.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 06:40 pm
Where is the "Lake Matthew" thread? That'd be a better spot to discuss this.

The Thistle Design is a hab, dealing with the same challenges any hab would encounter at this Mt. Sharp site.  There's no reason to move Thistle posts to another thread, just as there's no reason to move posts on towers, inflatables, glass geodesics, igloos, etc. to other threads.  Not if they're topical.  Or at least "amazing", I guess.

Actually it's interesting to compare the ways in which various designs address the challenges of a particular site.  Apples-to-apples, all that. 

What's your favorite?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/12/2016 07:19 pm
Nat Geo's take on Martian igloos made from regolith
http://www.dailymail.co.uk/sciencetech/article-3924260/Your-future-house-Mars-Martian-home-reveals-life-like-red-planet.html
Home for one person though? and how many airlocks are available?

Most of these "Little House on the Martian Prairie" ideas will never be built because they don't fit into any sensible settlement architecture. However we get to hear about these ideas from mass media because they are good mass consumption content for media. Kind of like how some cable science channels are only showing pseudoscience shows nowadays. Very popular but also quite useless other than as light entertainment.

Looks like the dome house is created using microwaved simulated regolith. If this technique really works on Mars then it can lead to larger (and much more useful) structures: tubes, spheres, larger domes covered with regolith for radiation protection.

A dome that size looks about right as a vestibule between human sized airlock and a larger structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 07:48 pm
Sinter Block

Looks like the dome house is created using microwaved simulated regolith. If this technique really works on Mars then it can lead to larger (and much more useful) structures: tubes, spheres, larger domes covered with regolith for radiation protection.

A dome that size looks about right as a vestibule between human sized airlock and a larger structure.

Some recent microwave regolith sintering refs and applications: Wilkinson et al. 2016 (https://www.researchgate.net/profile/Josef_Musil2/publication/303407153_Autonomous_Additive_Construction_on_Mars/links/5742082208ae298602ee2873.pdf).  Product looks a bit uneven still.  Better method?

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/12/2016 09:38 pm
Sinter Block

Looks like the dome house is created using microwaved simulated regolith. If this technique really works on Mars then it can lead to larger (and much more useful) structures: tubes, spheres, larger domes covered with regolith for radiation protection.

A dome that size looks about right as a vestibule between human sized airlock and a larger structure.

Some recent microwave regolith sintering refs and applications: Wilkinson et al. 2016 (https://www.researchgate.net/profile/Josef_Musil2/publication/303407153_Autonomous_Additive_Construction_on_Mars/links/5742082208ae298602ee2873.pdf).  Product looks a bit uneven still.  Better method?

Looks like this is only a paper study, no actual experiments. Their idea is to use swarm intelligence with different robot types, smallest type does the sintering, which is not a good idea, where do they get the power from?

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?

Not applicable to creating pressurised structures as it relies on the blocks being in compression. Might work for cut and cover tunnels. The video shows a process that is quite hard to automate.

Still looking at references, "Additive Construction using Basalt Regolith Fines" Mueller, et al. from 2014 says TRL about 3, still a long way to go before ready for use on Mars.

Given what I've read I'm really surprised that this dome house uses microwave sintering of simulated regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/12/2016 11:47 pm
Sinter Block

Looks like this is only a paper study, no actual experiments.

?  Paper refs for experiments:  Taylor and Meek (2005) and Barmatz et al. (2014).  Plus an experimental product is shown right there in the paper, photo Fig. 4e.  It's in the section on microwave sintering, titled

"Microwave sintering".

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?

Not applicable to creating pressurised structures as it relies on the blocks being in compression.

?  When you stack and bury the tunnel blocks, as in post and video, the tunnel is in compression, and can remain in compression even when pressurized to, for example, 60 kPa.  What are you trying to say? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 04:19 am
Under the Dome

This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.

Those towers would be very good radiation collectors, with a guaranteed "one-synod-and-out" policy for penthouse occupants.  Unless you made some major shielding mods.



The Thistle Design has a max clearance of ~90 m at the dome crown.  So you could construct ~25-story buildings inside the dome, around the facility's central interior pond.  Or you could, in theory, build a 30-story central tower above the central pond, if foundation pillars were sunk into pond bedrock, or, alternately, if the surrounding buildings were designed to buttress and carry the central tower entirely above the pond.

And even the penthouse suites would be fully shielded from radiation.

It would be interesting to see how the structural and material requirements for such a Mars complex would compare, quantitatively, with the counterpart on Earth.  I'd imagine the complex could be considerably more open, for one thing.  Better views. 

Any architects want to tweak a reference tower under 0.38 g, to see just how the requirements change? 

And lamontagne, want to try your hand at a fanciful complex sketch, to spark creative thinking?

Image:  just for scale, though I'm not sure how to scale for hobbits.  :)

(http://farm4.static.flickr.com/3474/4562740618_6435213f0b.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/13/2016 04:46 am
Under the Dome
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.
Those towers would be very good radiation collectors, with a guaranteed "one-synod-and-out" policy for penthouse occupants.  Unless you made some major shielding mods.
Nah, they would have much better shielding than other surface designs for the most part. They would lose very little atmospheric shielding by a few kilometers height (mars's atmosphere extends quite high due to the low gravity) and most levels would have the shielding of all the levels above. The penthouses would be about the same as a dome on the ground. I don't know if backscatter is an issue on mars but if so it could end up safer from that too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/13/2016 07:17 am
Sinter Block

Looks like this is only a paper study, no actual experiments.

?  Paper refs for experiments:  Taylor and Meek (2005) and Barmatz et al. (2014).  Plus an experimental product is shown right there in the paper, photo Fig. 4e.  It's in the section on microwave sintering, titled

"Microwave sintering".

That is not their experimental result, it is from Barmatz et al. (2014), and if you read that paper the experiments were on small samples in lab conditions. 200W microwave (don't say if it is input power or microwave power), 250 seconds to reach 400C (other places in the text mention 600C ), they also don't say the size of the sample, but given the average regolith grain size is small it looks to be about 1cm in diameter.

Given those figures it looks like 1MW can sinter 1 m3 in a day (24 MWh/m3).

Using 100kWh battery packs it would take 240 large robots to do the sintering autonomously.

EDIT: I'm surprised it takes so much power for sintering, perhaps I've made a mistake in the calculations or sintering small samples is not power efficient.

Zipper truck tunnels (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1603778#msg1603778) are rather clever.  Should be feasible with coarse regolith sinter, and readily automated, don't you think?

Not applicable to creating pressurised structures as it relies on the blocks being in compression.

?  When you stack and bury the tunnel blocks, as in post and video, the tunnel is in compression, and can remain in compression even when pressurized to, for example, 60 kPa.  What are you trying to say?

Looks like only to about 10 kPa, they need about 10 m of regolith compression. Good for cut and cover tunnels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/13/2016 12:39 pm
Lamontagne's towers can also work nicely if anchored in a cliffside and connected to tunnels at several levels. This makes the towers a vertical "outdoors" design element which ties together several levels of horizontal "indoors" elements.

Since the radiation protection is better inside the tunnels than in the towers, but the towers with their views and sunlight are better for providing a daily psychological booster, the use of towers built on cliffsides may be skewed more towards public/green spaces (such as farms, parks and Elon Musk's pizza joints) and generally attractions or places that people would want to visit, walk to or walk through several times a week.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 01:55 pm
Under the Dome
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.
Those towers would be very good radiation collectors, with a guaranteed "one-synod-and-out" policy for penthouse occupants.  Unless you made some major shielding mods.
Nah, they would have much better shielding than other surface designs for the most part. They would lose very little atmospheric shielding by a few kilometers height (mars's atmosphere extends quite high due to the low gravity) and most levels would have the shielding of all the levels above. The penthouses would be about the same as a dome on the ground. I don't know if backscatter is an issue on mars but if so it could end up safer from that too.

The problem is that there's negligible shielding around the penthouse, as given, so the dosage would be even higher than in e.g. McGirl et al. 2016 (https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/67500/ICES_2016_59.pdf?sequence=1), where 15 cm omnidirectional aluminum shielding was assumed.  Women under 40 would be especially vulnerable in the penthouse, approaching career exposure limit in the first synod.  On lower floors the tower would expose two-synod crews to dosages approaching limit. 

That's not good for multi-synod missions, much less settlement ambitions.  Hence the need for explicit and significant shielding in this or any long-duration hab.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/13/2016 02:03 pm
This building would be impossible on Earth, (I think) but probably doable on Mars.
Second image shows the scale better.

In fact I expect we could have tower many km high.  Why we want to build such things is another matter.

I really like these. Central core can carry elevators and utilities. Construction techniques similar to tower blocks on Earth.

From outside would look not too disimilar to https://en.wikipedia.org/wiki/St_George_Wharf_Tower or https://en.wikipedia.org/wiki/30_St_Mary_Axe
Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 11/13/2016 02:20 pm
For radiation reduction fit the towers with a sombrero. A couple of meter thickness of low atomic mass structure (swimming pool?). Very few cosmic rays come from the sides as the atmospheric depth is much greater towards the horizon.

Would still get a great view.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 04:03 pm
... they need about 10 m of regolith compression. Good for cut and cover tunnels.

Cover to suit, but the scenario does place a notional Roadheader (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1607257#msg1607257) on soft sandstone.  So why not use the Roadheader to cut, you know, the road?

...if you read that paper the experiments were on small samples in lab conditions.

If you read the paper you do see that, yes.  And 200 W is microwave power:  lab experiments aren't concerned with wall-plug efficiency. 

There is the option of sulfur concrete (https://arxiv.org/pdf/1512.05461.pdf).  Given that rich sulfate deposits are located within 6 km of the site, one could consider fabrication of the tunnel blocks from sulfur concrete, instead of sinter.  Net energy requirements might determine the method.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/13/2016 07:38 pm
Nah, they would have much better shielding than other surface designs for the most part. They would lose very little atmospheric shielding by a few kilometers height (mars's atmosphere extends quite high due to the low gravity) and most levels would have the shielding of all the levels above. The penthouses would be about the same as a dome on the ground. I don't know if backscatter is an issue on mars but if so it could end up safer from that too.

The problem is that there's negligible shielding around the penthouse, as given, so the dosage would be even higher than in e.g. McGirl et al. 2016 (https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/67500/ICES_2016_59.pdf?sequence=1), where 15 cm omnidirectional aluminum shielding was assumed.  Women under 40 would be especially vulnerable in the penthouse, approaching career exposure limit in the first synod.  On lower floors the tower would expose two-synod crews to dosages approaching limit. 

That's not good for multi-synod missions, much less settlement ambitions.  Hence the need for explicit and significant shielding in this or any long-duration hab.
Well sure. I would personally avoid a penthouse. Put something else like a water tank or vertical farming in the top levels.

Given we don't know the exact risks of radiation, underground is the safer option. And there are lots of other reasons too. I would definitely not charge off to mars having bound myself to the assumptions of towers. That is not going to happen though.

I was just comparing towers to other things we may put on the surface for whatever reason. A pent house on top would be no worse than a dome on the ground, and for lower levels it gets successively better.

Supposing radiation proves to be a huge problem, but it turns out that people psychologically need to look out real windows at a real horizon, towers are an excellent option for an above ground portion of your colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/13/2016 08:04 pm
My idea for a dome habitat would be an appartement tower in the center. Thick roof on top for radiation protection. Roof part of the dome structure. The tower can take part of the tensile load, reducing the load on peripheral anchors. Or is something wrong with that?

Around the tower would be a garden. Nice to have an outside of the living space with plants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/13/2016 10:23 pm
Roof part of the dome structure. The tower can take part of the tensile load, reducing the load on peripheral anchors. Or is something wrong with that?

If you were building dome and towers concurrently, you might integrate the loads.  It could reduce the number of anchors, somewhat.  However in most scenarios I think the dome goes up first, and any towers go up after, just due to the brutal site logistics.  Separated loads simplify construction.

Around the tower would be a garden. Nice to have an outside of the living space with plants.

Yes, it would be nice.  It's one reason the Thistle Design carries over the "hanging garden" of the notional Lake Matthew greenhouse.  A building complex with central tower could be raised to 30 stories.  Outside this complex are ~20 stories of dome-suspended garden:  for ballast against air pressure, for self-sufficiency, and of course, for the view.

When it's all done, connect building stories to garden stories.  With rope bridges?

(https://media-cdn.tripadvisor.com/media/photo-s/06/33/c9/bc/the-lost-gardens-of-heligan.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/14/2016 08:20 am
Roof part of the dome structure. The tower can take part of the tensile load, reducing the load on peripheral anchors. Or is something wrong with that?

If you were building dome and towers concurrently, you might integrate the loads.  It could reduce the number of anchors, somewhat.  However in most scenarios I think the dome goes up first, and any towers go up after, just due to the brutal site logistics.  Separated loads simplify construction.

Yes, I am assuming they would be built concurrently, if that were the design. In the sense that it is one project. Much easier to build the building first, then build the dome around it.
I don't think separated loads simplify construction. They simplify design but what is design complexity on that level in the age of computer simulation?
Title: Re: Envisioning Amazing Martian Habitats
Post by: CapitalistOppressor on 11/14/2016 04:05 pm
Here is an elaborate concept for a city built under airless conditions, circa 1987

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/15/2016 06:09 am
Here is an elaborate concept for a city built under airless conditions, circa 1987

Neat. ECLS and interfaces to other spheres at the bottom, oxygen and water tanks on top, habitable floors inbetween.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/15/2016 08:10 am
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1387863;image)

I think they copied that directly from here: St. Peter's Basilica

(https://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Petersdom_von_Engelsburg_gesehen.jpg/1280px-Petersdom_von_Engelsburg_gesehen.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: CapitalistOppressor on 11/15/2016 03:26 pm
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1387863;image)

I think they copied that directly from here: St. Peter's Basilica

(https://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Petersdom_von_Engelsburg_gesehen.jpg/1280px-Petersdom_von_Engelsburg_gesehen.jpg)

While Spaceball City was intended to be funny, it points to the fact that using spherical pressure vessels as habs, and having that concept inspire visions of off world cities is hardly new. 

IIRC Spaceship Earth at Epcot center was designed by Ray Bradbury, and shows that any serious thinking on the subject tends to quickly converge as the engineering realities dominate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 04:41 pm
Tunnel Trouble

An apparent problem for the Mt. Sharp Cut:  sandstone porosity

Was noodling on the notion of room-and-pillar (http://www.slideshare.net/hzharraz/room-and-pillar-mining-method) tunneling for extended hab space, beyond the notional Thistle Design's dome space.  The MF1 sandstone unit would be soft enough to cut with Roadheader.  However, porosity raises a problem for room-and-pillar tunnels.  Just ballparking, but what I see is:

MF1 thermal inertia (TI) is ~360 J/Km^2s^0.5.  This is "well-cemented sedimentary rock (http://onlinelibrary.wiley.com/doi/10.1002/2016JE005095/pdf)". 

But gypcrete ain't granite, and the cementing will be insufficient if the sandstone porosity is too high for compressive load.

A sandstone TI of 360 would have max, best-case density (http://onlinelibrary.wiley.com/doi/10.1029/2007JE002910/full) of ~2000 kg/m3.

That max density equates with porosity (http://petrowiki.org/File%3AVol1_Page_582_Image_0001.png) of 0.4.

Porosity of 0.4 equates with uniaxial compressive strength (UCS (http://)) of, effectively, zilch.

(http://petrowiki.org/images/7/77/Vol1_Page_652_Image_0001.png)

Result:  That means no pillars, however wide, can handle the load in a Mt. Sharp room-and-pillar scheme.  The rooms would not be safe without extensive shoring / anchoring of the ceiling, which would be a massive effort, literally and figuratively.



To attempt the room-and-pillar method, a sandstone of porosity < 0.2 would be required.  This equates with density > 2300 kg/m3, and TI > 500 J/Km^2s^0.5.

Somewhere else, apparently.

If I read that right.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/18/2016 05:18 pm
How very annoying of sandstone's part!

Perhaps the non weathered sandstone a few yards deeper is less porous though, since a pososity of 0.4 means we have 40% of void in the rock?  So its a lot more sand than stone!

Somewhere else then, or tougher rock, slightly metamorphic sandstone?  After all sandstone was used to build this:

The Strasbourg cathedral, build from pink sandstone.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 06:47 pm
Miner's Prospects

How very annoying of sandstone's part!...  Somewhere else then, or tougher rock, slightly metamorphic sandstone?"

Yeah, annoying and rather uncooperative.   :(

Metamorphism is very slight on Mars, absent tectonics.  So your parent material would need lithifying burial even deeper than that encountered by the Murray Formation units.  They're, what, maybe 1.3 km below the unconformity?  So exposures cutting deeper than that, I guess.

And the rock would probably need to be pre-Amazonian, because of aeolian contaminants.

The strength indicator would be an observed thermal inertia somewhere between 500 and 1000 J/Km^2s^0.5, I guess.  Having compressive strength, but not too much!   :o

Not an easy hunt.  But maybe a useful one.   What do you think, you want to go prospecting on NSF grant?

(http://3.bp.blogspot.com/_MtI4h_P-1ts/Sv8L22iuZsI/AAAAAAAAAF4/_wlG_IF23w8/s400/TheOldProspector.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/18/2016 07:00 pm
Miner's Prospects

How very annoying of sandstone's part!...  Somewhere else then, or tougher rock, slightly metamorphic sandstone?"

Yeah, annoying and rather uncooperative.   :(

Metamorphism is very slight on Mars, absent tectonics.  So your parent material would need lithifying burial even deeper than that encountered by the Murray Formation units.  They're, what, maybe 1.3 km below the unconformity?  So exposures cutting deeper than that, I guess.

And the rock would probably need to be pre-Amazonian, because of aeolian contaminants.

The strength indicator would be an observed thermal inertia somewhere between 500 and 1000 J/Km^2s^0.5, I guess.  Having compressive strength, but not too much!   :o

Not an easy hunt.  But maybe a useful one.   What do you think, you want to go prospecting on NSF grant?


Crashing meteorites will have produced some amount of metamorphism, and along the edges of volcanic plateaux there will be materials that have been modified by heat, and then buried, and then eroded away.  We don't need a gigantic area, after all, to build a city.  Just a set of conditions.
we're a bit far to go out with our hammer and microscope ;-).  I think at this point we should just decide if it is probable that such a combination can exist : Chemically clean, relatively soft rock, close to a good source of water, ideally with horizontal access.  Do all the mechanisms to create this exist on Mars?  If so, we can go ahead and fiddle with a city plan.  Schools, atriums, public areas?  Storage and functionalities? What type of city would be built, if started from scratch today? 


Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 07:49 pm
Chemically clean, relatively soft rock, close to a good source of water, ideally with horizontal access.  Do all the mechanisms to create this exist on Mars?

The mechanisms exist, or existed.  Have time and place conspired?  Dunno.

...we're a bit far to go out with our hammer and microscope ;-).

Still, you could go a long way with the existing maps of geology, topography and thermal inertia.

Chris should totally spring for the NSF grant, my opinion.   ;D



Update:  a nice contextual side-by-side (https://marstherm.boulder.swri.edu/) of apparent thermal inertia at our hypothetical Mt. Sharp worksite, and across the planet. 

With MARSTHERM "prospecting software".    8)

(https://marstherm.boulder.swri.edu/images/GaleCraterTesSeason.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/18/2016 08:27 pm
I've been in sandstone tunnels. I can tell you the strength isn't "zilch."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/18/2016 08:35 pm
How very annoying of sandstone's part!

Perhaps the non weathered sandstone a few yards deeper is less porous though, since a pososity of 0.4 means we have 40% of void in the rock?  So its a lot more sand than stone!

Somewhere else then, or tougher rock, slightly metamorphic sandstone?  After all sandstone was used to build this:

The Strasbourg cathedral, build from pink sandstone.

Yep. The medieval city walls of Famagusta, Cyprus, a big cathedral and Othello's Castle are all built from locally carved sandstone blocks, and they are still standing. Plus there are centuries old tunnels inside Famagusta's walls everywhere.

And let's not forget that the chemical bond strengths of two identical blocks of sandstone on Earth and Mars are the same, but Mars gravity is more forgiving at 0.38g.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/18/2016 08:55 pm
I've been in sandstone tunnels. I can tell you the strength isn't "zilch."

Have you built sandcastles, too?
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/18/2016 09:31 pm
I've climbed a lot of sandstone, it varies from cheese to almost as hard as rock. I guess the answer is 'it depends'.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rei on 11/19/2016 02:30 am
I'm not sure how to interpret the sedimentary rocks in pictures from the rovers in terms of strength.  They often seem to have "pancakes" of sediments jutting out to a degree I've never encountered on Earth.  I guess that means that the resistant layers must have some pretty good tensile strength (although the low gravity and lack of precipitation or strong winds surely also contributes to them not breaking off).

My personal experience is mainly with igneous rock (common on Mars).  Which is generally terrible, if your goal is low porosity or structural integrity in general (in addition to being loaded with vesicles, it tends to be highly fractured, as it cracks during cooling).  On the other hand, tuff is more of a sedimentary rock. I'm not sure of how good its gas permeability is, but it's easy to work, and can nonetheless be quite durable.  Some can also be a source of pozzolan for making pozzolanic concrete, which has lower porosity and greater durability than a simple portland cement concrete.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/19/2016 05:07 am
Yuty Prospect

Maybe Yuty Crater (http://www.lpi.usra.edu/publications/slidesets/craters/slide_6.html)?
22°12'N, 34°W

Pros:
- Late Hesperian (https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/thumbnails/image/6-Mars-a1.jpg) bedrock, likely ice-rich at time of impact (relatively clean rock, not aeolian)
- Unusually large central peak (possibly retaining pingo or other useful ground ice concentration)
- Pristine NW crater wall exposes basalt-containing rock, some sections with TI > 500 (http://www.hou.usra.edu/meetings/lpsc2015/pdf/1726.pdf) J/Km^2s^0.5.
- Wall exposure to ~1.5 km depth
- @22° N, good relative PV and temperature.  NW wall catches the sunlight.

Cons:
- Apparent thermal inertia suggests rock is near the low end of viable UCS.  However the notional TI/UCS rule-of-thumb is only ballpark, especially when rock type is speculative.
- Impact fracturing for weakened / shattered wall rock?
- ( ? )



Image:  YutyHypothetical1.png

Yuty Crater, showing bedrock exposures, NW exposure to left.  From video:  Mars Express, 2x vertical exaggeration (Yuty @1:00)

https://vimeo.com/125630557

Image:  YutyHypothetical2.png

Yuty Crater Thermal Inertia, red > 500 J/Km^2s^0.5

Image:  YutyHypothetical3.png

Yuty Crater night-time temperature with relatively warm wall exposure (red), suggesting highest UCS.  Showing also lobate ejecta, suggesting bedrock that was ice-or-water-rich at impact.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/22/2016 08:05 am
What about a dome within a dome within a dome ?
Pressurise the outer to 3 psi, the middle to 6 and the inner one to 10 psi.  A lot less stress on anchors, seams and joints in each dome than for a single, high pressure structure.  Still have to airlock between each but the equipment would be less massive.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/22/2016 08:57 am
What about a dome within a dome within a dome ?
Pressurise the outer to 3 psi, the middle to 6 and the inner one to 10 psi.  A lot less stress on anchors, seams and joints in each dome than for a single, high pressure structure.  Still have to airlock between each but the equipment would be less massive.

Sounds fine as long as everything is within specs. But a breach in one of the three domes and everything comes down like a house of cards, or maybe better like dominoes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/22/2016 09:17 am
We see that the crater provides a lot of potentially useful space.  With removal of what appears to be mostly sand debris, the 100 m+ deep crater would provide space for a 400 m Lake Matthew-style dome, having pressurized volume of ~6 million m3, all fully protected from surface radiation. 
400 m subaqueous titanium/ETFE dome (white).
[...]
At the end, air pressure reaches 60 kPa, average water depth reaches 5 m, and 180 perimeter rock anchors counter the dome's final net upward force of 800 million N.

If you mean that the water around the dome is 5m deep, then your net upward force is around 1.4 billion N; air pressure plus buoyancy. If you mean that the water covers the dome by 5m, the net upward force from buoyancy alone is 6 billion N.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/22/2016 09:36 am
What about a dome within a dome within a dome ? Pressurise the outer to 3 psi, the middle to 6 and the inner one to 10 psi.  A lot less stress on anchors, seams and joints in each dome than for a single, high pressure structure.  Still have to airlock between each but the equipment would be less massive.

You aren't really saving anything. Force scales linearly with pressure, so the net force is the same.

And either you've got a single set of deep anchors holding all three domes or three times as many shallow anchors. But the net force on those anchors, and thus the sum-total depth of anchorage, must be the same.

[Of course, if you have three independent rings of anchors, the second domes must be larger than the inner dome by enough space for its anchors to be biting into virgin rock, the outermost dome larger again. And larger domes experience more force that smaller ones, proportional to the square of radius. But force from atmospheric pressure only reduces linearly. So the net effect of your dome-within-a-dome-within-a-dome is that you end up needed to contain more force with three domes than one.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/22/2016 12:49 pm
Buoyancy and Ballast

We see that the crater provides a lot of potentially useful space.  With removal of what appears to be mostly sand debris, the 100 m+ deep crater would provide space for a 400 m Lake Matthew-style dome, having pressurized volume of ~6 million m3, all fully protected from surface radiation. 
400 m subaqueous titanium/ETFE dome (white).
[...]
At the end, air pressure reaches 60 kPa, average water depth reaches 5 m, and 180 perimeter rock anchors counter the dome's final net upward force of 800 million N.

If you mean that the water around the dome is 5m deep, then your net upward force is around 1.4 billion N; air pressure plus buoyancy. If you mean that the water covers the dome by 5m, the net upward force from buoyancy alone is 6 billion N.

Net 800 million N in this notional, ballasted configuration, yes.  Be sure to include the ballast.

Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy.   :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rei on 11/22/2016 01:11 pm
- Pristine NW crater wall exposes basalt-containing rock, some sections with TI > 500 (http://www.hou.usra.edu/meetings/lpsc2015/pdf/1726.pdf) J/Km^2s^0.5.
...
- Impact fracturing for weakened / shattered wall rock?

Basalt is almost always highly fractured, impact or not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/22/2016 03:27 pm
The Least Unkindest Cut

- Pristine NW crater wall exposes basalt-containing rock, some sections with TI > 500 (http://www.hou.usra.edu/meetings/lpsc2015/pdf/1726.pdf) J/Km^2s^0.5.
...
- Impact fracturing for weakened / shattered wall rock?

Basalt is almost always highly fractured, impact or not.

The important thing is UCS.  If impact fracturing shatters the rock, UCS tanks.  And complex craters like Yuty Crater have a lot of impact fracturing:

(http://www.newgeology.us/WWBowlComplex.jpg)



Image:  YutyHypothetical1.png

As evidence of shatter at Yuty Crater, we see extensive slumping in the NW wall (left).  Apparently some of the wall shattered on impact, lost its UCS, and collapsed. 

If there's more shattered rock in that wall, extending hundreds of meters in, the effort to shore up a tunnel entrance through that mess could be prohibitive.

Also the Yuty Crater rock wouldn't be parent basalt, but cemented sediment with basaltic grains, as opposed to, say, glassy grains.  Basaltic grains would explain the wall's relatively high TI (~600) which is nonetheless lower than that of parent basalt.  Even a basalt with a high porosity (0.4) would have a higher TI (~1000).



How to get around the UCS uncertainties stemming from impact violence to bedrock?   

Maybe one could prospect for exposures that were cut more gently, such as cuts from catastrophic floods, or from glacial scour.  These cuts would not produce shattered rock. 

Maybe, for example, somewhere along the 2.5 km cliffs of Kasei Valles?

(http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2006/08/kasei_valles_perspective_view_of_northern_branch_looking_west/9265323-5-eng-GB/Kasei_Valles_perspective_view_of_Northern_branch_looking_West_node_full_image_2.jpg)

Prospecting is hard work.   :-\
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/23/2016 02:06 am
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 

Displacement of water does. Your dome is displacing 6 million tonnes of water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/23/2016 03:02 am
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 

Displacement of water does. Your dome is displacing 6 million tonnes of water.
Im finding it a bit hard to get my head around this. I know that the weight of water sometimes makes it hard to pull out the plug at the bottom of a sink. I also know that something underwater containing air pushes up.

In the second case I can see why. The pressure of the water beneath is greater than the pressure of the water on top, because it is deeper.

As far as I can tell if something is sealed to the bottom it only feels the downward pressure and the situation is more like the plug at the bottom of the sink. But if it springs a leak then it becomes a huge flotation device and the roof instead of resisting compression must now resist stretching like a pressure vessel.

I get even more confused trying to picture the case in between compression and tension.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/23/2016 03:24 am
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 

Displacement of water does. Your dome is displacing 6 million tonnes of water.

Ah, no.  Get the physical meaning of "displacement" and "buoyancy", and you'll have the forces on Thistle Dome.   Good video:

https://www.youtube.com/watch?v=t-0iJ25zbcs
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/23/2016 03:51 am
Other Prospects

Bandfield et al. 2013 (http://faculty.washington.edu/joshband/publications/bandfield_global_crust.pdf)

Quote
On Mars, competent bedrock and block-dominated surfaces are
rare in older terrains. Less than 1% of the martian surface is composed
of surfaces dominated by high strength rocks, and exposures
of materials such as high strength blocky lava flows are extremely
rare (Edwards et al., 2009; Fig. 11). In addition, extensive regions
completely lack exposures of high strength rocks. Where we have
the ability to probe the martian subsurface through craters, canyons,
and other topographic features, THEMIS, CTX and HiRISE
observations suggest that the older martian crust is typically
mechanically weak and composed of weakly consolidated fine particulates.
By contrast, younger terrains of Hesperian and Amazonian
ages commonly show evidence for high strength crustal
materials where subsequent dust mantling and periglacial processes
have not occurred.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/23/2016 06:59 am
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 
Displacement of water does. Your dome is displacing 6 million tonnes of water.
Ah, no.  Get the physical meaning of "displacement" and "buoyancy", and you'll have the forces on Thistle Dome.   Good video:
https://www.youtube.com/watch?v=t-0iJ25zbcs

Conclusion of the video: "The buoyancy force is equal to the the weight of the displaced liquid"

What exactly did you think you were trying to prove?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/23/2016 09:07 am
Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 
Displacement of water does. Your dome is displacing 6 million tonnes of water.
Im finding it a bit hard to get my head around this. I know that the weight of water sometimes makes it hard to pull out the plug at the bottom of a sink. I also know that something underwater containing air pushes up. [...]
As far as I can tell if something is sealed to the bottom it only feels the downward pressure and the situation is more like the plug at the bottom of the sink. But if it springs a leak then it becomes a huge flotation device and the roof instead of resisting compression must now resist stretching like a pressure vessel.

When the plug is over a pipe full of air, the plug experiences more weight than buoyancy. But... and this is the key bit... the pipe-plus-plug combination is still experiencing buoyancy. The pipe is just bolted down sufficiently so you don't notice it.

But you can simulate this by filling a sink/bath/pool/etc with water and playing with a couple of bowls and a plate. (Neutrally buoyant is preferable, but slightly heavier than water is fine.)

Get a bowl and invert it, submerge it while capturing a nice big air-bubble, then let it go and it'll immediately rise up. Exactly as you expect. But even when you push it against the bottom of the sink/bath/pool/etc, the buoyancy is still present. It doesn't actually require water under the bowl.

"Ah", you think, "the water leaks under the rim, breaking the... seal... or... something." But the surface tension of water is enough to prevent this at ordinary pressures. You can show this by "cupping" two bowls, one upright and one inverted on top. Submerge them and the bottom (upright) bowl won't fill with water until you let the top bowl lift away. (If you raise the top bowl, rather than just letting it go, you can keep the air-bubble trapped under it, releasing only the air in the bottom bowl. Letting you see more clearly that the bottom bowl was indeed dry until that moment.)

This works even if the contact between the rims of the bowls is pretty uneven. If works when the gap is visible.

Note: If you hold the bottom bowl and let go of the top (inverted) bowl, the top bowl will immediately rise, just as it does normally. There's no suction from the air in the bottom bowl.

Now submerge the inverted bowl again, but this time put a plate under the bowl, essentially using a plate instead of the bottom of the sink/bath/pool/etc, when you let go of the bowl, it still rises immediately. Same as it did when you pressed it against the bottom of the sink/bath/pool/etc.

Now repeat this with the bowl upright (opening at the top) and the plate on top. Submerge the two together. Not only will water not leak under the plate (as mentioned, surface tension of the water is enough to prevent leaks at this pressure), but as long as you hold onto the bowl the plate will happily sit on top of the air-bubble, the plate won't lift up when you let it go. (The plate easily slides from side to side, there's no real "seal".) That's the same effect that keeps your plug plugged. You can even "burp" the plate a few times and it will tend to get sucked back down onto the bowl (just as the sink plug does.)

Now let go of the bowl too.

The bowl/plate combo remains as buoyant as it was when inverted. (And obviously, you'll realise this while having to hold the bowl down.) This is the same buoyancy that also acts on the drain-pipe of your sink, just without you realising it.

It's the thing actually displacing the liquid which experiences the buoyancy, not the plug on top.

And in wstewart's proposals, that's the dome. It will experience an upward force equivalent to the weight of 6 million tonnes of displaced water trying to tear it off its anchors. The water just makes the dome problem worse.

---

Aside: Video of a buoyant "plug" because I'm easily amused.

https://www.youtube.com/watch?v=P5uxv2ZJPTc
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/23/2016 05:33 pm
F(bot)

Water covers the dome at average depth of 5 m.  And water on a roof does not produce buoyancy. 
Displacement of water does. Your dome is displacing 6 million tonnes of water.
Ah, no.  Get the physical meaning of "displacement" and "buoyancy", and you'll have the forces on Thistle Dome.   Good video:
https://www.youtube.com/watch?v=t-0iJ25zbcs

Conclusion of the video: "The buoyancy force is equal to the the weight of the displaced liquid"

What exactly did you think you were trying to prove?

As in Prof. van Biezen's video, displacement puts the object's lower surface in contact with the liquid.  And as in the video, liquid pressure contact exerts upward force F(bot) on that surface.

F(bot), and only F(bot), is the upward buoyancy force.

Thistle Dome lacks that lower surface contact, so there's no liquid displacement, no F(bot), no upward buoyancy force.  The only upward force is air pressure * area.  Accounted for.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/24/2016 01:54 am
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,

A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.

Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/24/2016 03:31 am
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,

A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.

Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.

No, you just confused force from air pressure with buoyancy force. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/24/2016 07:48 am
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,
A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.
Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
No, you just confused force from air pressure with buoyancy force.

Buoyancy is in addition to the uplift from air-pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/24/2016 03:29 pm
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,
A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.
Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
No, you just confused force from air pressure with buoyancy force.

Buoyancy is in addition to the uplift from air-pressure.

It doesn't work that way.

(http://i.imgur.com/pJ6MSei.gif)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/25/2016 06:16 am
F(bot), and only F(bot), is the upward buoyancy force.
Thistle Dome lacks that lower surface contact, so there's no liquid displacement,
A dome (inverted bowl) cupped on the bottom of a sink/bath/pool/etc also lacks the "lower surface contact", yet experiences buoyancy.
Your dome is no different than building a dome on the bottom of any lake/ocean on Earth. You cannot just arbitrarily exclude buoyancy.
No, you just confused force from air pressure with buoyancy force.
Buoyancy is in addition to the uplift from air-pressure.
It doesn't work that way.

So try it.

An air-filled dome fully-submerged on the bottom of a tub of water should (according to your reasoning) experience no buoyancy, provided there's no water underneath the dome. And without the 600kpa excess air-pressure, it should experience no lift at all. In fact the dome should be held down by the weight of the column of water above it.

Go try it.

(https://s-media-cache-ak0.pinimg.com/originals/2f/5d/d2/2f5dd2541f167b50584360dbecf63a2c.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/25/2016 07:56 am
How about this? what I have done is place a glass bowl in a sink over the plug, right way up, and taped some plastic sandwich wrap over it, sealing the edges firmly. Then I filled the sink with water.

I argue that all the plastic-wrap that is clearly curved downwards is feeling a downwards force. No part of it attempts to form an upwards bubble.

(http://i68.tinypic.com/2s6rq0n.jpg)

Interestingly, the flat plastic-wrap covering the bowl itself remained pretty much flat as far as I could tell. It felt strange to the touch, not under tension that I could tell. I think it formed a proper seal and thus no air could be pushed out and down the plughole. Im sure that if I had used a bowl with a way for air to escape down the plughole, it would have formed a downwards curving dome.

Note: when I pulled a corner of the black tape up allowing water to enter, the plastic wrap immediately converted to an upward pulling dome shape, even as the water began pouring down the plughole.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/25/2016 11:29 am
How about this?

Nice! At least someone is willing to play along. Props for getting a good seal with the tape.

I argue that all the plastic-wrap that is clearly curved downwards is feeling a downwards force.

Mainly an inward force from the sides, I suspect.

I did something similar, but using a plate as a base and a tall narrow glass as a central support. The sides bowed inwards, exactly as yours, but the air gathered around the top and pushed upwards. Essentially it tried to form a buoyant sphere.

[My tape wouldn't stick to the sink surface enough to stop the glass'n'bubble from lifting off (too damp, I expect, even after I dried it). So I had to resort to sticking it to the plate, which had to be held underwater by hand, so no pics. Sorry. I might try with the bathtub tomorrow. It needs cleaning anyway.]

Hence...

No part of it attempts to form an upwards bubble.

...I suspect in your set-up, some air was able to leak through out the drain.

Try repeating it with a plug in place, or on a solid part of the sink.

Interestingly, the flat plastic-wrap covering the bowl itself remained pretty much flat as far as I could tell. It felt strange to the touch, not under tension that I could tell.

You get the same effect when you place a flat plate over a bowl. The bowl remains buoyant, but the plate sits loosely on top of the bowl. Neither lifted by the air, nor pressed down by unsupported the column of water. Its buoyancy is exactly the same as if the air-filled bowl wasn't there.

Did you try getting an air-filled bowl (inverted) to sit on the bottom of the sink, like wstewart's dome?

Interestingly, you can get a solid-but-buoyant object to "stick". With difficulty. If the bottom of the object and the tub are both very flat and you add a hydrophobic layer between them (lard!). In order to lift, it must create a vacuum. A small change in height creates a large increase in "volume" below the object, hence a large reduction in pressure, enough to resist buoyancy.

But no matter how much grease I slather around the base of a "dome", it will not stay down. A small lift creates almost no change in air pressure inside the dome, hence no resistance to buoyancy. The same will be true of wstewart's dome (or worse because of the over-pressure.)

I suspect the only way to "stick" a dome would be to pump the air out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/25/2016 04:11 pm
Moon Pool

Interestingly, the flat plastic-wrap covering the bowl itself remained pretty much flat as far as I could tell. It felt strange to the touch, not under tension that I could tell.

Because...?

There's no tension if no net force.  Here weight of water above the film is a force of same magnitude as force from air pressure below. 

Note: when I pulled a corner of the black tape up allowing water to enter, the plastic wrap immediately converted to an upward pulling dome shape, even as the water began pouring down the plughole.

Because...?

Drainage reduces water depth above the film, and weight.  Result:  net upward force, putting film into tension as a dome.

(And of course, no F(bot), no buoyancy force.)



Seal the drain and water enters the dome until base water pressure equalizes with dome air pressure. 

Result:  moon pool (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608957#msg1608957)

Would be funny to see model astronauts exiting your dome through a moon pool.  Elon would totally twig on that.   :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/25/2016 10:14 pm
No part of it attempts to form an upwards bubble.

...I suspect in your set-up, some air was able to leak through out the drain.

Try repeating it with a plug in place, or on a solid part of the sink.
That was by design though. There was always a bit of water trickling in but it was slow enough that it didn't equalise the pressure. When I pulled up the edge, it immediately ballooned upward into a dome.

Ah. I just realised something. I haven't really been following the exact subject that the moot is about. Something about buoyancy vs being weighed down.

I don't dispute that the buoyancy would lift up a sufficient portion of whatever ground the dome is attached to. If the ground is not one monolithic solid object then water pressure can get beneath and start pushing.

I think the actual interesting question is this: Is the force of buoyancy transmitted through tension on the plastic film pulling, or from pushing from beneath, ie does the dome material have to be built to withstand those huge lifting forces?

In my experiment the film over the top of the bowl was flat, not under tension. I believe any lifting pressure was on the underside. IMO your base has to be strong, watertight, and of sufficient mass, but your roof material can be weak.

Im not sure if this is exactly what you guys were discussing though. The above can be tested more simply by just taping a plastic cover under over a bowl and holding the bowl underwater by force. My guess is that the plastic film roof would remain fairly flat and not strain upward, probably dip down sightly due to pressure, though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof. Ideally the strong part is a monolithic lump of rock that is large enough that dome+rock mass/volume exceeds density of water.

(I just tested this and of course it is true. The top of the bowl does not bulge upwards. It had a slight downwards curve but was hard to judge. I expect if the water was deep enough it would bulge downward because the air inside is being compressed by the water sitting on top of it.)



Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 03:57 am
though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof.

Remember in that case it's the bowl that contains the air, and the bowl that experiences the buoyancy. The cling-film is flat, thus experiences no buoyancy.[*] To replicate wstewart's submerged dome, you'd need to hold an air bubble with the cling-film alone. For example, a flat plate with an air-filled cling-film "dome", or taping an air-filled "dome" of cling-film to the bottom of the sink before filling it.

The buoyancy is present no matter what you do.

Wstewart believes that he can treat it as a ballast force and ignore the buoyancy, that submerging a dome actually makes things easier.

[*Other than from it's own internally generated displacement volume, which is trivial.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/26/2016 04:47 am
though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof.
Remember in that case it's the bowl that contains the air, and the bowl that experiences the buoyancy. The cling-film is flat, thus experiences no buoyancy.[*] To replicate wstewart's submerged dome, you'd need to hold an air bubble with the cling-film alone. For example, a flat plate with an air-filled cling-film "dome", or taping an air-filled "dome" of cling-film to the bottom of the sink before filling it.

The buoyancy is present no matter what you do.
Im not fussed about that part though. The dome has to be connected to a massive monolithic piece of stone. The stone has to perform the roll of this bowl. If the density of the dome+stone is less than that of water, it would rise.

The only interesting point to me is that the material of the dome itself does not feel huge forces, or any particular force at all if the air pressure inside balances the water pressure outside. Even at the edges where it connects to the stone it does not feel any pressure like you would experience trying to hold down a diving bell.

There is huge pressure trying to pull this thing up but it is not transmitted by the roof material tugging upwards. Rather the roof has lessened the weight of the column of water pressing down from above, and it is this imbalance that tries to lift the floor up if any ambient water pressure can get beneath it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 05:48 am
Erebus Montes Prospect
34° N 177° W

Maybe an improvement on the previous prospects for accessible tunnel-ready rock with nearby ice deposits.

Pros:

- Early Hesperian rock, probably without aeolian contaminants
- > 600 TI, exceeding minimum UCS for tunneling
- 1 km sunlit exposure at 34 N, for good PV
- widespread evidence of geologically recent glacial and periglacial effects, for possible remnant subsurface ice

Cons:

- -3800 m entrance elevation, marginal atmospheric pressure for liquid water
- rock type(s) and UCS uncertain
- remnant subsurface ice concentration unknown
- no crater at tunnel entrance locations; wall/plain structure required



Image:  ErebusMontesHypothetical1.png

High TI units outlined, esp. in Arcadia Planitia, from Bandfield et al. 2013 (http://faculty.washington.edu/joshband/publications/bandfield_global_crust.pdf).

Image:  ErebusMontesHypothetical2.png

Glacier-like forms, esp. in Arcadia Planitia, from Souness et al. 2012 (http://geomorphology.sese.asu.edu/Papers/souness_etal_2012.pdf).

Image:  ErebusMontesHypothetical3.png

Block mesas near Erebus Montes, possibly with remnant glacial fill between blocks.  1 km sunlit southern exposures.  Note filled crater 2 km S of mesas, possibly with remnant subsurface ice.

Image:  ErebusMontesHypothetical4.png

Night IR of mesas, showing higher TI of exposures (brighter).

Image:  ErebusMontesHypothetical5.png

Debris apron around mesa, possibly with remnant glacial fill.

Image:  ErebusMontesHypothetical6.png

Concentric crater fill example, 50 km SW of mesas, possibly with remnant subsurface ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 07:28 am
Im not fussed about that part though. The dome has to be connected to a massive monolithic piece of stone. The stone has to perform the roll of this bowl. If the density of the dome+stone is less than that of water, it would rise.

That was what started this. Wstewart believes that submerging the dome reduces the upward force from the air-pressure. That the water acts as ballast and doesn't add an entire extra buoyancy effect to deal with.

though the bowl itself strains upward. So something has to be strong, but not your transparent domed roof.
Remember in that case it's the bowl that contains the air, and the bowl that experiences the buoyancy. The cling-film is flat, thus experiences no buoyancy. To replicate wstewart's submerged dome, you'd need to hold an air bubble with the cling-film alone. For example, a flat plate with an air-filled cling-film "dome", or taping an air-filled "dome" of cling-film to the bottom of the sink before filling it.
The only interesting point to me is that the material of the dome itself does not feel huge forces, or any particular force at all if the air pressure inside balances the water pressure outside.

That's not the case. You are confusing the flat cover (which doesn't experience buoyancy) with the walls of a dome.

The dome will be crushed in from the side, and push up through the top. (Essentially it's trying to form a sphere at the same time as it's trying to rise.)

and it is this imbalance that tries to lift the floor up if any ambient water pressure can get beneath it.

It doesn't require water underneath, it only requires the absence of a vacuum wide enough to overcome the net buoyancy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/26/2016 08:01 am
That's not the case. You are confusing the flat cover (which doesn't experience buoyancy) with the walls of a dome.

The dome will be crushed in from the side, and push up through the top. (Essentially it's trying to form a sphere at the same time as it's trying to rise.)
That might be true. I did actually wonder about that before reading this, and if I should repeat the experiment with something other than a flat surface.

It is still not a big issue to me. For something underwater I don't care about the sides. The roof could be a flat surface and not a dome if it turns out that is the only shape to which this principle applies. Simply by making the area sufficiently large, the cost of the walls becomes a small fraction of the cost of the roof, which does not need any particular strength if the air is at the same pressure as the water. At 30 meters on Mars that would match earth sealevel. I imagine pillars dotted around because even if the roof is at equilibrium, it is not particularly stable and could even exhibit waves.

The transparent roof could be quite cheap. The underside can be as cheap, rigid and as heavy as you like, ideally a massive piece of ground but it could also be a freefloating thing build of concrete or whatever.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 01:02 pm
Cheap Digs

The roof could be a flat surface and not a dome...

Yes.  Thistle Dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608957#msg1608957) has slight curvature for tensioning and aesthetics.

...the roof, which does not need any particular strength if the air is at the same pressure as the water. At 30 meters on Mars that would match earth sealevel.

Yes.  Thistle Dome moon pool (stemwall base) is at ~15 m because dome is at 60 kPa.  Crown exterior is notionally at 3 m (sunlight through shallow water).  Surface in tension, perimeter ring in compression.

I imagine pillars dotted around because even if the roof is at equilibrium, it is not particularly stable and could even exhibit waves.

A single-piece film would be a wavy mess all right, and hard to fabricate at scale.  In contrast, Thistle Dome is conceptually modular:  hexagons fabricated in shirtsleeves, lifted through the fab roof airlock one-by-one for dome assembly.   Titanium ribs for rigidity.  No waves.

The transparent roof could be quite cheap. The underside can be as cheap, rigid and as heavy as you like, ideally a massive piece of ground but it could also be a freefloating thing build of concrete or whatever.

Bedrock is cheap, yep.  ETFE is not as cheap (http://www.polymerplastics.com/fluoro_tefzel.shtml), but you'd expect bulk discount.   :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 01:31 pm
For something underwater I don't care about the sides.

Work out the crushing force per square metre.

And you've still got to deal with the buoyancy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 03:37 pm
Cooler Insulation

If room-and-pillar tunneling should prove feasible, how might the space be thermally regulated?

Near-surface rock averages ~ -60 C at useful latitudes, and living quarters would be in direct conductive contact with that rock.  Insulation would be necessary, and lots of it.

For comparison, the South Pole station is elevated off the ice, minimizing conductive heat loss.  Even so, insulating panels are pretty thick, at 124 mm:

Quote
Sandwich Composite Panels (http://static.monolithic.com/pdfs/thesis/quimby.pdf)
These panels, made of plywood on both sides with core insulation between them, were used in the construction of modular structures (living accommodation, kitchen, etc.)....  [T]imber frame was used and the panel thickness was 124 mm (12 mm thick marine plywood on each side and 100 mm core polyurethane foam insulation)...   [T]he floor needed additional insulation, because temperatures varied from -4ºC at the floor to 15ºC at the ceiling.

Just as baseline:

Polyurethane foam (http://www.madehow.com/Volume-6/Polyurethane.html) density is maybe 100 kg/m3.  Marine plywood, maybe 800 kg/m3.   If you double the South Pole foam thickness to handle rock conduction (enough?), the composite panel density becomes 176 kg/m3.

Result:  A cubic room 4 m on a side, with one open wall, would need 3 tons of insulation.

Not that you'd use those materials, obviously.  Other insulating materials are needed, via ISRU, and in bulk. 

Questions:  What can be made via ISRU, and how much is needed, to insulate that 4 m room?

(https://s-media-cache-ak0.pinimg.com/564x/df/bf/aa/dfbfaab786763c4c750b5c65a7d24a78.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/26/2016 07:04 pm
The best insulation would be a vacuum layer, then you would have only radiation, and could reduce that with low e and reflective materials.

What could be better than nothing at all as far as ISRU goes  :-)  Mars atmosphere is practically vacuum, after all.

We could start with some kind of alumimised  paint that manages to stick to the tunnel wall (already a first challenge). then strips of poorly conducting but pressure resistant materials, molten basalt bricks with lots of hollows might serve.  Arrange these so they occupy no more than 10-15% of the area, and no more that 10cm wide, so 10cm lattices, 1 cm thick (20x2 might be easier to build).  Then a strong wall, metal or FRP, holding in the air pressure, but beeing supported by the lattice, so no need to be very thick.  The outside of the wall could be painted with low-e coatings as well.  The vacuum gap works at all thicknesses, but 2cm min. would be easier to build.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2016 07:16 pm
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/26/2016 07:44 pm
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

Yes, but perhaps not necessarily through our load bearing walls, specially if they are full of ice, and that ice is part of the structural strength.
That being said, i'll admit I was just answering the problem posed by wstewart.  Hadn't really thought if there was a problem there in the first place  ;-)

If the thermal flow through the walls is too low, a very likely possibility in plant growing areas, then we might need active cooling.  I've recently done some grow rooms that had loads up to 1000 W/m2, so those needed refrigeration to be livable.  If we practice high intensity underground agriculture, and we probably will, then we may need to provide for some means of circulating a lot of heat and removing it to the surface to radiate away.  Or create sufficiently large heat sinks to have it absorbed by the soil.
I've heard enough stories about frozen geothermal wells though to know these might not be a very effective solution.  Melting ice and then letting it evaporate into the Martian air would probably be the simplest system.

Another possibility might be an equilibrium between underground heat gains and glass domes heat losses.  You can insulate the tunnels, to ensure a simple energy balance, in particular if you design simple domes with high heat losses, and then just use hot air to transport the heat around the base.  You would need to circulate the air anyway, for health, air treatment and plant growth reasons.





Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/26/2016 09:15 pm
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

Any Mars habitat will have internal and external, active and passive heat sources, heat exchangers and heat sinks. These can all be carefully designed and tuned to produce robust thermal equilibrium. All fascinating things to talk about but maybe too far down in the weeds for the purposes of this thread! We can go back to envisioning amazing habitats and assume that there will be sufficient degrees of freedom to engineer robust thermal regulation for almost any (high level) habitat design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 09:26 pm
Light Bulb in the Freezer

Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

A wall-insulated Canadian basement at 4 m scale loses heat to the ground at a rate of roughly 600 W (http://web.mit.edu/parmstr/Public/NRCan/nrcc23378.pdf) (adapted from Appendix A). 

Comparison:  The uninsulated Mars room, sited within much colder ground, and with an extra ground-conducting wall, would lose heat at a rate well beyond a kW. 

Meanwhile the brave settler's body radiates only 100 W -- almost literally a light bulb in the freezer. 

Inference:  To attempt heat balance, we'd need insulation achieving more than an order-of-magnitude reduction in heat loss rate.  Two orders of magnitude might be a good starting point.

Addendum for Lumina: Unless that is, you want to just line the walls with many kilometers of heat exchange loops, and warm up the mountain for fun.  OPM!   :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/26/2016 09:33 pm
I think you overestimate the heat loss to the Martian regolith if you have a huge habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/26/2016 10:26 pm
Vacuum Tile?

The best insulation would be a vacuum layer, then you would have only radiation, and could reduce that with low e and reflective materials.

What could be better than nothing at all as far as ISRU goes  :-)  Mars atmosphere is practically vacuum, after all.

We could start with some kind of alumimised  paint that manages to stick to the tunnel wall (already a first challenge). then strips of poorly conducting but pressure resistant materials, molten basalt bricks with lots of hollows might serve.  Arrange these so they occupy no more than 10-15% of the area, and no more that 10cm wide, so 10cm lattices, 1 cm thick (20x2 might be easier to build).  Then a strong wall, metal or FRP, holding in the air pressure, but beeing supported by the lattice, so no need to be very thick.  The outside of the wall could be painted with low-e coatings as well.  The vacuum gap works at all thicknesses, but 2cm min. would be easier to build.

So a... vacuum tile? 

If you can make a low-density basaltic brick with interior vacuum space, yeah, that might be a useful approach.  Glaze it front and back with low-e coating.  Add some press-and-click lattice mounting bracket to the back, for omnidirectional paving...  Hmm...   

What do you think?  Is there a method for manufacturing a low-density basaltic brick that can hold vacuum within?   And any idea what R-value (https://www.archtoolbox.com/materials-systems/thermal-moisture-protection/rvalues.html) you might end up with?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/27/2016 12:00 am
Mars regolith would be much better insulation than Canadian soil due to the  near-vacuum.

Additionally, a dome will have a large footprint, which means for a given area, it will saturate the soil with warmth well before a Canadian basement would.

I agree with those who say insulating the ground will not be hard.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/27/2016 12:12 am
Mars regolith would be much better insulation than Canadian soil due to the  near-vacuum.

Additionally, a dome will have a large footprint, which means for a given area, it will saturate the soil with warmth well before a Canadian basement would.

I agree with those who say insulating the ground will not be hard.

?  How do any of those assertions apply to heating of a pressurized rock tunnel room, the topic of the page?
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/27/2016 06:24 am
Re: Insulation in a tunnel.

You guys do realise that an inhabited space will need to get rid of heat, not retain it?

Yes, but perhaps not necessarily through our load bearing walls, specially if they are full of ice, and that ice is part of the structural strength.
That being said, i'll admit I was just answering the problem posed by wstewart.  Hadn't really thought if there was a problem there in the first place  ;-)

If the thermal flow through the walls is too low, a very likely possibility in plant growing areas, then we might need active cooling.
I have done some interesting math on something related: A megawatt of waste heat deep under the ice could keep a sphere of water a kilometer across liquid at equilibrium. The temperature remains fairly stable regardless, a bit above freezing, instead the volume grows.

(That rabbit hole begins here:
http://forum.nasaspaceflight.com/index.php?topic=40628.msg1564606#msg1564606)

(however it is important to note that it would take thousands of years to reach that equilibrium.. A megawatt of energy is only about enough to melt a 170 tons of ice a day, and something a kilometer across is of the order of a billion tons)

This is potentially very useful, but also could make many underground concepts very unstable.

This is why I have a bunch of ideas similar to wstewart, though mine for the most part are pretty fuzzy.

Roughly they are:
* Deliberately create our waste heat underground (or under ice). Probably also direct sunlight there eg with light pipes.
* Live at a depth of about 30 meters, where there is robust 1atm pressure.
* Have a floating layer of some material lighter than water (it could for example be mass produced water filled bags with small air pockets) with a mass of around 1ton/m2. This will provide enough pressure to prevent water boiloff in average mars conditions.
* Dont rely on the strength of frozen ice or regolith, or in fact the strength of anything. Everything is ordered the way it should be by gravity.

You can start very small, even a curiosity sized rover could set up something like this before humans arrive. There is no real limit to the size it could grow to as more people arrive and create more waste heat. It could be a form of paraterraforming where a suburban city and ocean just grow together until it covers thousands of square km.. Also the same basic idea can be applied to any icy world from here out to the Oort cloud. Entire worlds could become oceans under protective eggshells of ice, so easily it might be an unintended consequence.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2016 06:59 am
What do you think?

When Elon Musk has suggested, that digging caves would be an easy method of providing living space or space for production did he have people do some math on heat disspation and other potential problems like insulation or is it just a off the cuff remark?

My guess there is some careful deliberation behind it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/27/2016 07:45 am
Re: Insulation in a tunnel.
You guys do realise that an inhabited space will need to get rid of heat, not retain it?
Meanwhile the brave settler's body radiates only 100 W -- almost literally a light bulb in the freezer.

So you expect the power consumed by colonists, by all systems inside the inhabited space, ECLSS, electronics, computers, growing areas, etc, will be... zero?

ISS uses about 25kW per person. Mir aimed for just over 10kW per person, but was severely underpowered at less than 5kW per person.

If a large base on Mars consumes less than 1kW per person, I will eat a space heater.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/27/2016 08:02 am
What do you think?
When Elon Musk has suggested, that digging caves would be an easy method of providing living space or space for production did he have people do some math on heat disspation and other potential problems like insulation or is it just a off the cuff remark?
My guess there is some careful deliberation behind it.

Musk does tend to throw ideas around fairly off-the-cuff.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/27/2016 01:11 pm
I think you overestimate the heat loss to the Martian regolith if you have a huge habitat.

This is a very important design point. As the dimensions of a habitat increase, heat loss to the environment increases as the exterior area. However, livable volume increases faster than the exterior area. So heat loss per unit volume of habitat decreases as the continuous habitable volume goes up.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 11/27/2016 01:30 pm
Having the equipment to dig tunnels and caves to live in solves several problems, beyond low radiation habitations.  Those include mining for raw materials, initially water in large quantities, a place to store the water underground, possibly underground storage for oxygen and methane, and eventually mining for other industrial raw materials. There could be a vast network of interconnected tunnels and caves where people spend most of their lives. Kind of creepy, but more practical than having to put on pressure suits to go out all the time, especially for kids.

I think it may be practical to grow as much food as possible in greenhouses on the surface pressurized with Mars atmosphere, but would need a lot of automation since people would have to wear suits to work there as it will be mostly CO2 except for the O2 produced by the plants. They can provide supplemental lighting at night to allow 24/7 growth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2016 02:03 pm
Plants could not stand that much CO2. It would have to be a mix of CO2, oxygen, nitrogen plus argon as there would be a surplus of it from fuel production and it would do no harm. Probably still too thin for humans if you go for the minimum needed by plants. But if it is half of what humans need, it may be much easier to design counterpressure suits. They would need to span a smaller pressure difference and they would make working there much easier than spacesuits. Still mostly automated, I agree.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 11/27/2016 03:20 pm
Vacuum Tile?

The best insulation would be a vacuum layer, then you would have only radiation, and could reduce that with low e and reflective materials.

What could be better than nothing at all as far as ISRU goes  :-)  Mars atmosphere is practically vacuum, after all.

We could start with some kind of alumimised  paint that manages to stick to the tunnel wall (already a first challenge). then strips of poorly conducting but pressure resistant materials, molten basalt bricks with lots of hollows might serve.  Arrange these so they occupy no more than 10-15% of the area, and no more that 10cm wide, so 10cm lattices, 1 cm thick (20x2 might be easier to build).  Then a strong wall, metal or FRP, holding in the air pressure, but beeing supported by the lattice, so no need to be very thick.  The outside of the wall could be painted with low-e coatings as well.  The vacuum gap works at all thicknesses, but 2cm min. would be easier to build.

So a... vacuum tile? 

If you can make a low-density basaltic brick with interior vacuum space, yeah, that might be a useful approach.  Glaze it front and back with low-e coating.  Add some press-and-click lattice mounting bracket to the back, for omnidirectional paving...  Hmm...   

What do you think?  Is there a method for manufacturing a low-density basaltic brick that can hold vacuum within?   And any idea what R-value (https://www.archtoolbox.com/materials-systems/thermal-moisture-protection/rvalues.html) you might end up with?
Microwave oven.

By Micowaveing the basalt regolith it can be formed in to a solid hard brick of any shape. It is also possible to do an additive process 3D printing that adds material while microwaving to create complex shapes with internal hollows. This equipment would take some significant development but would be an easy building material manufacturing system that does not require significant refinement process before use. A screening process to remove rocks. The finer the powder the better. The fine powder would enable smooth shapes and surfaces. A sandy consistency would probably have higher strength (maybe).

See the information about using similar process on Lunar regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/27/2016 03:41 pm
I think you overestimate the heat loss to the Martian regolith if you have a huge habitat.

This is a very important design point. As the dimensions of a habitat increase, heat loss to the environment increases as the exterior area. However, livable volume increases faster than the exterior area. So heat loss per unit volume of habitat decreases as the continuous habitable volume goes up.
Area goes up to the square and volume to the cube.  In general, of course.  Strain also goes up to the cube of the dimensions (or the square, I forget  :-(, so there is an optimal point between maximum volume and acceptable strain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/27/2016 08:10 pm
Hew Thermopylae - Draft 1

OK, taking a first shot at "Hew Thermopylae", a tunnel-hab that is notional only, and not much loved by the designer. 

For discussion.  Draft 1.  Hypothetical, very.



Quote
At length they drew near New Thermopylae; where, that same evening, Mrs. Hominy would disembark.  A gleam of comfort sunk into Martin's bosom when she told him this.  Mark needed none; but he was not displeased.
It was almost night when they came alongside the landing-place.  A steep bank with an hotel, like a barn, on the top of it; a wooden store or two; and a few scattered sheds.
"You sleep here to-night, and go on in the morning, I suppose ma’am?" said Martin.
"Where should I go on to?" cried the mother of the modern Gracchi.
"To New Thermopylae."
"My! ain’t I there?" said Mrs. Hominy.
Martin looked for it all round the darkening panorama; but he couldn’t see it, and was obliged to say so.
"Why that's it!" cried Mrs. Hominy, pointing to the sheds just mentioned.
"That!" exclaimed Martin.
"Ah! that; and work it which way you will, it whips Eden," said Mrs. Hominy, nodding her head with great expression.

-Charles Dickens, "The Life and Adventures of Martin Chuzzlewit"




Working assumptions of this notional tunnel-hab:

Erebus Montes prospect (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1613485#msg1613485) is the site.  Other ideas are welcome of course, but that's the most promising site my cursory prospecting has turned up.

Mesa UCS:  45 MPa

Safe pillar load:  16 MPa  (loosely inferred from Mathey and van der Merwe 2016 (http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-223X2016000300015))

Pillar square side:  15 m

Gallery width:  6 m

Room height:  4 m



For the brave 300 of this Hew Thermopylae, we have the following rough design:

Image:  HewThermopylaeHypothetical1.png

General method of Roadheader room-and-pillar tunneling.

Image:  HewThermopylaeHypothetical2.png

Room-and-pillar living/working space.  One dormitory unit having 8 dorm rooms and a common space in center.

Image:  HewThermopylaeHypothetical3.png

Layout for 300.  Paired dorm units, with 5 east-west main hallways, repeated across 1.6 km.  3 equipment bays to N.  A pair of 600-m tunnels to S entrances.

Image:  HewThermopylaeHypothetical4.png

S exposure of the block mesa. 

Image:  HewThermopylaeHypothetical5.png

Hab plan overlaid on mesa.

Image:  HewThermopylaeHypothetical6.png

Google Mars perspective view of S exposure.  The two entrances are marked with blue squares.



"What about..."  Yeah, I got that thing totally wrong.  ;)  But just a few notes to start:

Total pressurized volume:  320,000 m3

Dorm room volume: 180 m3

Overall volume per resident, including common spaces and halls, excluding equipment bays and entranceways:  980 m3

Tunnels are cut with a pair of Sandvik Roadheader MR620 (http://www.miningandconstruction.sandvik.com/sandvik/0120/Internet/Global/S003713.nsf/Alldocs/Products*5CContinuous*2Dmining*and*tunneling*machines*5CRoadheaders**2D*tunnel*miners*2AMR620/$FILE/Brochure_MR620.pdf) equivalent machines.  With conveyors and other equipment, tunneling requires ~ 2 MW continuous power.  Assuming power is direct PV, tunneling is restricted to ~ 6 hours per sol.  Tunnels are completed in ~ 2000 days, or 5.5 Earth years.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 02:19 am
"How to survive the winter?"

Previously lamontagne calculated heat flux through his insulated ovoid dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1605896#msg1605896).  I inferred that the dome's 22,000 m2 surface area would radiate heat at ~ 800 kW on a -90 C winter night.  How to survive the winter in that dome?  I recall we were thinking about layering thick insulation around the dome, or just abandoning it til spring.  (!)

At Hew Thermopylae the heating problem appears order-of-magnitude worse -- and winter bug-out isn't an option.  Hew Thermopylae living quarters have an order-of-magnitude more surface area, ~ 220,000 m2.  If the -60 C rock conducts a very hypothetical 38 W/m2, it could conduct out an order-of-magnitude more heat, at ~ 8 MW.

The spartan 300 produce a mere 30 kW of heat themselves, leaving a stubborn deficit of, still, ~ 8 MW. 

Maybe a heat exchanger could pump that 8 MW into the rock, if you had 8 MW of heat to exchange.  (And if you had an exchanger clever enough to avoid pipe freeze-burst at -60 C, when pumps glitch.)  You'd just need the 8 MW.  You'd need it in winter, when PV sits idle 18 hours per sol. 

So the 8 MW comes from... 

ah...

Well, the question again becomes, "How to survive the winter?" 

Absent a pricey and hot-blooded nuclear reactor, the need for insulation does seem critical here.  220,000 m2 of hab area needs coverage.  If you had a recipe for lamontagne's clever "vacuum tiles (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1613644#msg1613644)", let's say, and each tile covers [x] and masses [y] and burns [z] Joules in fabrication... 

Hmm... 

[noodling]

(http://www.aljazeera.com/mritems/Images/2015/11/30/a3a17370d15d460f805e1150476246a9_18.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 02:55 am
"How to survive the winter?"

Previously lamontagne calculated heat flux through his insulated ovoid dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1605896#msg1605896).  I inferred that the dome's 22,000 m2 surface area would radiate heat at ~ 800 kW on a -90 C winter night.  How to survive the winter in that dome?  I recall we were thinking about layering thick insulation around the dome, or just abandoning it til spring.  (!)

At Hew Thermopylae the heating problem appears order-of-magnitude worse -- and winter bug-out isn't an option.  Hew Thermopylae living quarters have an order-of-magnitude more surface area, ~ 220,000 m2.  If the -60 C rock conducts a very hypothetical 38 W/m2, it could conduct out an order-of-magnitude more heat, at ~ 8 MW.

The spartan 300 produce a mere 30 kW of heat themselves, leaving a stubborn deficit of, still, ~ 8 MW. 

Maybe a heat exchanger could put that 8 MW into the rock, if you had 8 MW of heat to exchange.  (And if you had an exchanger clever enough to avoid pipe freeze-burst at -60 C, when pumps glitch.)  You'd just need the 8 MW.  And you'd need it in winter, when PV sits idle 18 hours per sol. 

So the 8 MW comes from... 

ah...

Well, the question again becomes, "How to survive the winter?" 

Absent a pricey and hot-blooded nuclear reactor, the need for insulation does seem critical here.  220,000 m2 of hab area needs coverage.  If you had a recipe for lamontagne's clever "vacuum tiles (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1613644#msg1613644)", let's say, and each tile covers [x] and masses [y] and burns [z] Joules in fabrication... 

Hmm... 

[noodling]


Well, we certainly don't want poor Thermpylae to die of cold.  The main answer depends on a question: do they produce their own food?  If yes, then they must produce it the way we do on Earth, through photosynthesis.  As we can find out easily, this is not a very efficient process, 2% for crop plants.  So our 100 Watts per colonist requires 100/0.02= 5 kW per colonist.  A gain of 50 is requires as an aboslute minimum.  A gain of 100 would be very good, IMHO.  So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth.  This is an absolute minimum, we haven't added any other processes, such as transportation, production of goods, air circulation, water circulation, etc.
 
The colony is in danger of heat death!  And this is because of absolutely unavoidable food production.  Suddenly these glass domes that lose a lot of heat are looking good...



Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:09 am
Any skeptics about vacuum tiles?

Just in case, I suggest a trip to Wikipedia: https://en.wikipedia.org/wiki/Multi-layer_insulation
or
A variation of this is the Vacuum insulation panel: https://en.wikipedia.org/wiki/Vacuum_insulated_panel
or
A third possibility is foam glass, that should be possible to produce in situ: https://en.wikipedia.org/wiki/Foam_glass

Mars atmosphere is practically a vacuum.  These should all work just fine.  Just pick your favorite.

But remember, any food producing underground base will want to get rid of heat.  So insulation may not be required, except for comfort near the walls.  And because the plants need the heat.

A Mars base is just a plant's way to get light and heat.  They will give you some seeds in exchange  :-)

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 03:15 am
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

(http://photojournal.jpl.nasa.gov/jpeg/PIA00576.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:16 am
A final point about thermodynamics of underground bases.  Conduction equation is Q=AdT/R.
dT is the temperature difference between the interior of the base and the soil.  R in the insulation value of the materials.
Now, as your soil heats up, the thickness of the warm soil around the base and the original cold soil gets thicker and thicker.  Eventually, you will have a few meters of warm soil, and it will now serve as insulation.

Any underground base that is sufficiently deep will reach an equilibrium where the heat loss becomes negligible, and eventually overheat.  The only exception is if the heat reaches the surface and starts radiating away.

The Earth is a perfect example of this. 12-20 km of Rock, with  an overall R value of many thousands, has been keeping the core hot for billions of years... (plus the radioactive materials in the core, of course). 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:19 am
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 15 MW

in winter

at night

on Mars?


Insulate your base with the patented 'Lamontagne Tiles'.  No more heat loss ;-)  Produce twice the food you need in summer, as reasonable people do.  Eat the surplus in winter.  Since you are not producing food in winter, you are adding much less heat to your base.  Win-win.


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:22 am
You can also get a nuclear reactor.  They always solve everything. 
But solar only is so much more Fun!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 03:32 am
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

(http://photojournal.jpl.nasa.gov/jpeg/PIA00576.jpg)
Build near the equator, as I suggest. Melas Chasma in Valles Marineris is a good spot, nice and low with a great view and available water. Don't need 30MW at night because you'll have daytime and a lot of thermal inertia. And you'll have a lot of batteries.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 03:35 am
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

Build near the equator, as I suggest. Melas Chasma in Valles Marineris is a good spot, nice and low with a great view and available water. Don't need 30MW at night because you'll have daytime and a lot of thermal inertia. And you'll have a lot of batteries.
And don't grow the food at night, never a good idea!
Robot is right, build the base with a lot of heavy walls, and a lot of water tanks.  It'll be both nicer, less noisy and have plenty of thermal inertia.  The surface swings up and down depending on the sun, underground, it's all smooth and calm...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 03:48 am
Oh, and also, each refueling of a BFS requires approximately 0.5-1MW of power on average. Some of that power is lost as waste heat in the exothermic Sabatier reaction or inefficiencies of electrolysis. Because I'm too lazy to calculate, I'd bet it's around half of the power ends up as low quality waste heat that could be used for heating the colony space, just like waste heat from generators at the South Pole is used for heating, too. So 250-500kW per BFS

So if you have 100 BFS refueling every year, that's about 30MW of heat on average, plus the solar gain you get on that huge glass dome, etc. And with 1000BFSes, that's 300MW of heat. With 10,000 BFSes, 3GW of heat.

I think waste heat will be largely sufficient for base operations. In a pinch, you could burn some ISRU fuel, but it'd have to be an emergency.

Waste heat from ISRU, waste heat from photosynthesis (good call on the factor of 50, so about 5kW per colonist just in waste heat from inefficient photosynthesis), plus solar thermal gain from glass dome, insulation, and thermal inertia. I agree that rejected heat may end up being the more annoying problem long-term as the base grows.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 04:02 am
A final point about thermodynamics of underground bases.  Conduction equation is Q=AdT/R.
dT is the temperature difference between the interior of the base and the soil.  R in the insulation value of the materials.
Now, as your soil heats up, the thickness of the warm soil around the base and the original cold soil gets thicker and thicker.  Eventually, you will have a few meters of warm soil, and it will now serve as insulation.

Any underground base that is sufficiently deep will reach an equilibrium where the heat loss becomes negligible, and eventually overheat.  The only exception is if the heat reaches the surface and starts radiating away.

The Earth is a perfect example of this. 12-20 km of Rock, with  an overall R value of many thousands, has been keeping the core hot for billions of years... (plus the radioactive materials in the core, of course).

Right, ultimately you want the rock to stop being a heat sink, and start insulating.  Problem is, each m3 of rock soaks up ~ 200 million Joules on its way to room temperature.   Long road, deep mountain.  But it would be very interesting to see how the 1-D thermal profile under the hab room evolves over time, with various heat inputs.  Starting point is of course a stubborn -60 C.

Speaking of thermal profiles, maybe it's worth noting that the martian crust has a profile rather more cruel than Earth's.  Even an extremely deep hab, at 2 km depth, would be surrounded by rock at ~ -40 C, which is not very helpful.  A hab at equilibrium (in room temperature bedrock) would have to hit a sick depth of ~ 8 km.  A very diligent Sandvik MR620, running 6 hours per sol on a 10 degree cut, would need about 40 years to reach the front door. 

If it doesn't hit basalt.  :o
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 04:05 am
Let's say we have 100 tons of material per colonist that is heated to room temperature. Assume it has a heat capacity of 1J/(gram*degreeC) (water has 4J/(g*C)). So that's 1E8J per degree C. So let's say we allow up to 20degreesC temperature change. That's 2E9J per colonist. Even if all power is cut, the whole thing is plunged into utter darkness and everyone's metabolism stops, that means if we have 1kW of heat loss per colonist, it'd take over 20 days to eat through all that thermal inertia.

Triple that if you also had 10 tons of water (or 40 tons of rock/sand) heated to near boiling by Sabatier waste heat (which is optimally 300-400C).
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 04:41 am
So the colonists need 3 MW of photosynthesis, i.e light.  But since plants are not 100% food, you will probably need 5 to 10 times more.  So now your base is overheating because of the lights required for plant growth...

?  But where to get 30 MW

in winter

at night

on Mars?

(http://photojournal.jpl.nasa.gov/jpeg/PIA00576.jpg)
Build near the equator, as I suggest. Melas Chasma in Valles Marineris is a good spot, nice and low with a great view and available water. Don't need 30MW at night because you'll have daytime and a lot of thermal inertia. And you'll have a lot of batteries.

Thermal inertia from sunshine doesn't warm the winter tunnel.  We couldn't even manage solar heating of an insulated winter greenhouse, as I recall, which is why we had to abandon lamontagne's dome for the season.  But you might try heating water with winter flux, to see what you get.

As for batteries, flow batteries are presently state-of-the-art at this scale.  A 100 ton flow battery can deliver, I think, maybe 70 billion J of electrical heating.  At a 30 MW burn rate, that lasts half an hour.

How to survive the winter?
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/28/2016 08:37 am
And don't grow the food at night, never a good idea!

Unless you have that nuclear reactor that wants to produce power day and night. You would probably want a set of greenhouses that are lighted in turns.

But why do I argue this? I am much in favor of greenhouses using mostly ambient light and maybe some added light for peak biomass production for some crops during part of their growth cycle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 11:54 am
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/28/2016 12:04 pm
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 12:38 pm
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 02:39 pm
PV or not PV?

Just to quantify the winter PV problem at Hew Thermopylae:

1 ton of state-of-the-art PV produces ~ 100 kW, summer high-noon max.

Hew Thermopylae is at 34° N, where winter sunlight intensity drops to ~ 15% of summer max.

So in winter, that's 15 kW max, maybe 160 million Joules / sol. [corrected]

If that energy were stored and released on-demand with 80% efficiency, that's 130 million Joules/sol of heat energy.

And with a hypothetical 8 MW conductive heat loss, the uninsulated tunnels would need 700 billion Joules / sol.

So 5400 tons of PV, just for heat. 

(http://i.dailymail.co.uk/i/pix/2015/02/11/258E7F9500000578-2948238-image-a-5_1423625677289.jpg)

And assuming no winter storms (https://www.nasa.gov/mission_pages/msl/multimedia/vasavada-4.html).  :o
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/28/2016 02:55 pm
Perchlorates are both an energy and oxygen source.

This is not a microbial astrobiology thread, Senior Member Robotbeat.
I'm not talking about astrobiology.

The equivalent of Martian Coal?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/28/2016 03:06 pm
How to survive the winter?

Good old fashioned engineering and planning.

Once you have a Mars base with ISRU that produces breathable air, drinkable water, and food you are in pretty good shape. If a habitat design can't maintain a livable temperature, then it's time to design a different habitat. If a location can't produce enough solar power during winter, you need to pick a better location.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/28/2016 03:20 pm
And his hydrogen comes from a bottle, gratis.

No it doesn't. Half of the hydrogen goes into water and needs to be recovered by electrolysis.

Edit: Some power is needed for controlling gas flow and pumping the process products but that is miniscule in comparison to the amounts produced.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 03:31 pm
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
You are ignoring scale which is why Zubrin needed input power for a very exothermic reaction. If you're doing megawatts of Sabatier youll need to dump heat to keep your reactor from melting
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 04:58 pm
And his hydrogen comes from a bottle, gratis.

No it doesn't. Half of the hydrogen goes into water and needs to be recovered by electrolysis.

Edit: Some power is needed for controlling gas flow and pumping the process products but that is miniscule in comparison to the amounts produced.

His hydrogen comes from a bottle.  In his shop.  Obviously electrolysis is required on Mars, pulling even more electrical power.  Point:  even the exothermic Sabatier reactor requires electrical power, continuously, by itself.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 05:18 pm
PV or not PV?

Just to quantify the winter PV problem at Hew Thermopylae:

1 ton of state-of-the-art PV produces ~ 100 kW, summer high-noon max.

Hew Thermopylae is at 34° N, where winter sunlight intensity drops to ~ 15% of summer max.

So in winter, that's 15 kW max, maybe 22 million Joules / sol.

If that energy were stored and released on-demand with 80% efficiency, that's 18 million Joules/sol of heat energy.

And with a hypothetical 8 MW conductive heat loss, the uninsulated tunnels would need 700 billion Joules / sol.

So 40,000 tons of PV, just for heat.


Isn't 15 kW x 3600s x 6 hrs = 324 million joules?  so 2000 tonnes rather than 40 000 tonnes?
If you stop food production and fuel production during winter, and insulate the base to a heat loss of 2 MW, then 500 tonnes of solar cells would be enough to keep you warm.  No reason you couldn't go bellow 2 MW with a well insulated base, and keep some production capacity going.

In summer, the cells would produce 6.6 times more energy, so 13.2 MW, enough for basic food production, then another 500 tonnes would produce 25 MW, enough food to pass the winter, and fuel for the ships.

If you had sun tracking solar panels, you could probably do better than these numbers; less mass or more energy.

And some of these powers are used twice, once for Sabatier fuel production, then, the lower grade losses can be used to heat the base, or again, 95%+ of the plant light turns into heat, that can also be used to heat the base.  So most of the time no heating load.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 05:22 pm
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
You are ignoring scale which is why Zubrin needed input power for a very exothermic reaction. If you're doing megawatts of Sabatier youll need to dump heat to keep your reactor from melting

A Sabatier reactor is not a nuclear reactor.  It's chemistry:  net useful energy output < electrical energy input.  Losses occur at each step, and no practical design catches all the waste heat at each step.  So we minimize steps, ideally down to just one:  convert PV electrical power directly to heat, for example in a tunnel heating wire. 

But of course PV itself is a problem in winter, because there doesn't seem to be nearly enough (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614102#msg1614102). 

Disagree?  Well, you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/28/2016 05:39 pm
If we need 25 MW of installed solar power to run a 300 person base, and these are about 0,1 kw per m2 (summer), then we need 250 000 m2 of solar panels?  A bit more than 500m x 500m?  does that seem about right? And a 10 000 person base would be about 3 x 3 km?  And the 1 million people target city 30 km x 30 km?

Most likely spread out among a number of smaller communities, or will Mars generate a single big city and a number of mostly robotic outposts?






Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 06:04 pm
Sabatier waste heat (which is optimally 300-400C)

Sabatier reaction is exothermic, but it can't run at a scale to heat Hew Thermopylae in winter because the energy input required to maintain the reaction is far too high, as I think (http://forum.nasaspaceflight.com/index.php?topic=41575.msg1607587#msg1607587) you know.  It's more efficient to heat electrically, from PV, and skip intermediary processes.  But in winter the PV for tunnel heating just isn't there.

As you stated the Sabatier reaction is exothermic. It does not need any energy input to run except the initial energy to get it to operating temperature.

Needeed is hydrogen from water electrolysis, this indeed needs a lot of energy. You can produce the hydrogen during the day and keep the Sabatier reaction going all night.

The reaction needs hydrogen, heat and pressure, yes, and exothermy doesn't get us there, unfortunately.  As example, Zubrin's unit (http://ascelibrary.org/doi/10.1061/%28ASCE%29AS.1943-5525.0000201) is predicted to output 1 kg/hr, while requiring 700 W electrical, continuous.

And his hydrogen comes from a bottle, gratis.
You are ignoring scale which is why Zubrin needed input power for a very exothermic reaction. If you're doing megawatts of Sabatier youll need to dump heat to keep your reactor from melting

A Sabatier reactor is not a nuclear reactor.  It's chemistry:  net useful energy output < electrical energy input.  Losses occur at each step, and no practical design catches all the waste heat at each step.  So we minimize steps, ideally down to just one:  convert PV electrical power directly to heat, for example in a tunnel heating wire. 

But of course PV itself is a problem in winter, because there doesn't seem to be nearly enough (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614102#msg1614102). 

Disagree?  Well, you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see.
Youre not getting it.   You need to make the methane anyway and you get waste heat as a byproduct
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 06:13 pm
Where do the losses go? Waste heat. Which we can use.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 06:26 pm
Also build on the equator melas  and use lighter weight PV
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 08:01 pm

...you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see [net heat recovered for Hew Thermopylae].
 

Youre not getting it.   You need to make the methane anyway and you get waste heat as a byproduct


Just try to sum the energies into and out of the Sabatier/electrolysis system (including heat lost and recovered), and then I think you'll ballpark the fraction of tunnel heat you get from Sabatier PV, relative to what direct PV heating can give.  Which itself isn't enough, but still.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 11/28/2016 08:11 pm
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 08:28 pm

...you can sum the energy inputs and outputs in a Sabatier/electrolysis system, and just see [net heat recovered for Hew Thermopylae].
 

Youre not getting it.   You need to make the methane anyway and you get waste heat as a byproduct


Just try to sum the energies into and out of the Sabatier/electrolysis system (including heat lost and recovered), and then I think you'll ballpark the fraction of tunnel heat you get from Sabatier PV, relative to what direct PV heating can give.  Which itself isn't enough, but still.
You still are attacking something I'm not saying.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 08:32 pm
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/28/2016 08:46 pm
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat

Waste heat is still usable.  If it can be redirected as actual heat for the colony, that is.

      What seems to escape many peoples' notice, Mars is VERY, very cold.  Every bit of heat that can be scavenged, from whatever source available, should be scavenged.

      Obviously, some heat sources are so low in thermal production, or too far or mobile, to be of use, but all fixed sources, putting out significant amounts of waste heat, should be utilized, if at all possible or practical.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 08:47 pm
Isn't 15 kW x 3600s x 6 hrs = 324 million joules?  so 2000 tonnes rather than 40 000 tonnes?

It'd be ~15 kW at high noon, but it drops off after.  And I see I got the drop-off wrong.  Correction:  more like 160 million Joules/day, for 130 million Joules of useful heat at 80% conversion.  So maybe 5400 tons of PV.  All just ballpark.  Corrected above.

If you had sun tracking solar panels, you could probably do better than these numbers; less mass or more energy.

Actually I've read that stationary panels are doing well now at capturing off-axis light, without sun tracking hw.  So I just assumed that, and didn't allocate any mass for sun trackers.

... the lower grade losses can be used to heat the base...

Was wondering about that low-grade waste heat.  If it heats exchange-loop water to, say, room temperature, is that enough to prevent freeze-burst as the loop conducts heat into the cold rock?  Wouldn't we want water near boiling point in the loops?  But am unsure what temperature range you had in mind.

[Or maybe these things lead to sghill's other thread (http://forum.nasaspaceflight.com/index.php?topic=34836.400).]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/28/2016 09:05 pm
We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat

Waste heat is still usable.  If it can be redirected as actual heat for the colony, that is.

      What seems to escape many peoples' notice, Mars is VERY, very cold.  Every bit of heat that can be scavenged, from whatever source available, should be scavenged.

      Obviously, some heat sources are so low in thermal production, or too far or mobile, to be of use, but all fixed sources, putting out significant amounts of waste heat, should be utilized, if at all possible or practical.
Meh, average temperatures even during winter are no worse than Earth South Pole during winter night. And Mars is near vacuum so lower thermal transfer rates
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/28/2016 09:14 pm
Yurt?  Dirt?

We've been off-topic for a while.  We have a thread for power source discussions.

http://forum.nasaspaceflight.com/index.php?topic=34836.420
Sabatier isn't a power source.  it produces waste heat

Waste heat is still usable.  If it can be redirected as actual heat for the colony, that is.

      What seems to escape many peoples' notice, Mars is VERY, very cold.  Every bit of heat that can be scavenged, from whatever source available, should be scavenged.

      Obviously, some heat sources are so low in thermal production, or too far or mobile, to be of use, but all fixed sources, putting out significant amounts of waste heat, should be utilized, if at all possible or practical.

Cold sure enough.  And yes, you'd scavenge heat wherever practical, sure. 

Actually I'm wondering if maybe the heating problem is so bad that it renders this tunnel-hab concept more trouble than it's worth.  "By an order of magnitude," even.   :)   -60 C rock is just such an excellent heat conductor, and when it surrounds the crew on nearly every side, day and night... 

Well, maybe Hew Thermopylae is just an exercise in "problems of Xtreme hab design," without a ready solution. 

Question:  Anybody vote to exit the mesa now, and apply our painful knowin' to more forgiving hab designs, outside?

(https://media-cdn.tripadvisor.com/media/photo-s/0d/70/1b/0a/aidar-yurt-camp.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 11/28/2016 09:14 pm
Enough about heat and power production. Don't do an offtopic post and link to another thread, just post in the other thread.

Thanks.

Edit: Heat is fine, agreed, heat rejection/generation/storage is important and doesn't have other homes at present. But any of the usual Nuclear/Solar is better/worse cheaper/costlier safer/dangerous-er stuff? Right Out.

Thanks
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/29/2016 03:57 am
Enough about heat and power production. Don't do an offtopic post and link to another thread, just post in the other thread.

Thanks.

Thank you. Proposals for amazing habitat concepts - especially when paired with a specific proposed location on Mars - would be great additions to this thread.

(Edit: this thread should not concern itself with energy and heat sources. There are many options and degrees of freedom to solve any energy supply or thermal balance problem on Mars. For the purposes of this thread let's assume that energy/heat are solved and just go ahead to propose amazing hab concepts)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/29/2016 04:29 am
There are no threads that concern chiefly with heat. This is the only one that really focused on it. Makes sense as heat management is one of the chief constraints of habitat design. I challenge the idea that it's off-topic here! Power, on the other hand, has like a billion cajillion threads devoted to it and isn't so directly coupled to habitat design (solar makes the most sense in vast fields and nuclear would be placed a safe distance from the habitat).

By the way. My keyboard was broken, so I wasn't able to properly respond. So let me do it now.

Musk has mentioned three habitats.
1) The ITS itself (clearly off-topic here)
2) Glass domes (has its own thread)
3) Tunnels (which seems to be the focus of this thread)

In reference to the last one, Musk mentioned that the tunnels would be used for industrial equipment. Even though this thread has had a lot of speculation about living in tunnels, it seems like Musk is implying people would live in the glass dome with tunnels for industry.

What do we know about industrial equipment on Mars? The biggest (besides the off-topic power production) are:
1) Electrolysis of water
2) Sabatier reaction of water with CO2
3) possibly extraction of water from the soil, although it seems to me this is best done out on the surface

Any kind of energy-intense industrial process is going to have waste heat. And the easiest place to dump it is not the thin Martian air but the air of the pressurized industrial tunnels, even though they'll be at higher temperature than the outside air. Filling up the ITS in a synod is going to take about half to a full Megawatt of electricity. Most of that is losses and doesn't end up as methane chemical energy. So if you have a thousand ITSes refueled every synod, that's hundreds of megawatts of heat you get automatically for free. No extra power required. It's already needed.

In Minnesota, we sometimes get a week where it doesn't get above zero. And the wind is brutal, carrying any heat quickly from your body. But the Mall of America was designed entirely without a heating system. It relies entirely on waste heat from sunlight coming in the massive skylights, artificial lighting, internal equipment, and warm bodies. I think a Mars settlement would be similar.


I like the Sabatier reaction as an example because it operates at high temperatures and so you have more options about what you do with the waste heat. You can, for instance, put it deep within the regolith underlying the settlement. So deep that the heat pulse produced by summer's excess electrical capacity (dumped still in the Sabatier process) doesn't reach the surface until the middle of winter when it's needed most. So the regolith itself is acting as a reservoir of heat and a sort of delay buffer to even out the heat flow.

And you don't need to really worry about pipes freezing. It's likely you'd use ethylene glycol or propylene glycol for the heat loop. Both are fairly easy to make via ISRU. Or even methanol. And the deep soil is already naturally at a high enough temperature to prevent freezing in that case. And even more so once you've dumped any kind of significant amount of heat into the soil. The ground will stay relatively warm for years.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 11/29/2016 05:13 am
Quote
In reference to the last one, Musk mentioned that the tunnels would be used for industrial equipment. Even though this thread has had a lot of speculation about living in tunnels, it seems like Musk is implying people would live in the glass dome with tunnels for industry.

I have experienced first hand how just a spring melt can cause an otherwise relatively safe mine to become active and worthy of concern.  Even several hundred feet below a mountain, water finds it way into the mine and can cause minor to major cave ins.  Granted water will not be the issue on mars, but changes caused by heat may well be.  If your plan is to constantly pump heat into tunnels, I hope you aren't planning on making those places habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 07:14 am
Siting Industrial Equipment For Habs

Quote
In reference to the last one, Musk mentioned that the tunnels would be used for industrial equipment. Even though this thread has had a lot of speculation about living in tunnels, it seems like Musk is implying people would live in the glass dome with tunnels for industry.

I have experienced first hand how just a spring melt can cause an otherwise relatively safe mine to become active and worthy of concern.  Even several hundred feet below a mountain, water finds it way into the mine and can cause minor to major cave ins.  Granted water will not be the issue on mars, but changes caused by heat may well be.  If your plan is to constantly pump heat into tunnels, I hope you aren't planning on making those places habitats.

Tunnel-hab is not my preference, no.  You wouldn't have spring melt, but I imagine the walls might "sweat" when heated.  Could get messy -- or messier.   :o

If these pressurized tunnels aren't used as habs, but only as equipment bays, why build them?  Why not just design the industrial machines to work on the surface, perhaps in a pressurized cargo module, perhaps under a loose protective tent?  What could justify the great expense and difficulty of the dig, if inhabitation isn't the goal?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 09:52 am
Don't want to live in holes?  Here is Megatower!

1 km high.  Self supporting through air pressure, megatower has an external pykrete skeleton made up of 3 free standing columns than serves as backup if the internal pressure is lost. Internal arrangement is independent from the outer shell.

Megatower is protected from radiation by a minimagnetosphere that cover about 10 km2.  The little white smudge besides the tower is an ITS spaceship.  The slightly larger shape is a pickle type tower.

Each core is 60m in diameter and weighs 25000 tonnes.  It is supported by the air pressure exerted on the dome at the top of the tower.  The windows are light polycarbonate, the structure composite.

The pykrete columns are water and sand, reinforced with basalt fiber rods.  Wind loading is negligeable despite the structure's size.  As the columns are exterior to the habitat, they do not melt.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 01:33 pm
Oz Beneath the Magnetic Cloud of Protection

Don't want to live in holes?  Here is Megatower!

1 km high.  Self supporting through air pressure, megatower has an external pykrete skeleton made up of 3 free standing columns than serves as backup if the internal pressure is lost. Internal arrangement is independent from the outer shell.

Megatower is protected from radiation by a minimagnetosphere that cover about 10 km2.  The little white smudge besides the tower is an ITS spaceship.  The slightly larger shape is a pickle type tower.

Each core is 60m in diameter and weighs 25000 tonnes.  It is supported by the air pressure exerted on the dome at the top of the tower.  The windows are light polycarbonate, the structure composite.

The pykrete columns are water and sand, reinforced with basalt fiber rods.  Wind loading is negligeable despite the structure's size.  As they are exterior to the habitat, they do not melt.

Pykrete, it's not just for aircraft carriers (http://www.discovery.com/tv-shows/mythbusters/about-this-show/what-is-pykrete/) now?  :)  And the facility is a lovely form, very Oz!  8)

As I understand it, pykrete gets its essential strength and low thermal conductivity from wood pulp fiber.  And I can understand why you might not want to ship pulp, and reinforce instead with ISRU basaltic fiber rods.  But why replace pulp with sand?  Wouldn't sand raise thermal conductivity significantly, without strength benefit?  Summertime seems challenging, with sand forcing measurable ice melt / sublimation on the columns, on those days when the surface regolith (sand) can exceed 20 C.

As for the magnetosphere, are you considering the notional balloon-encapsulated variant on Bamford et al. (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1604130#msg1604130), or something else?  If you go with an encapsulated form, can you add such a form to the illustration?  Should be a conversation-piece:  "Oz Beneath the Magnetic Cloud of Protection".   ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/29/2016 01:51 pm
Don't want to live in holes?  Here is Megatower!

Now that's "Envisioning Amazing Martian Habitats" on a grand scale.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 02:13 pm
Oz Beneath the Magnetic Cloud of Protection


Pykrete, it's not just for aircraft carriers (http://www.discovery.com/tv-shows/mythbusters/about-this-show/what-is-pykrete/) now?  :)  And the facility is a lovely form, very Oz!  8)

As I understand it, pykrete gets its essential strength and low thermal conductivity from wood pulp fiber.  And I can understand why you might not want to ship pulp, and reinforce instead with ISRU basaltic fiber rods.  But why substitute pulp with sand?  Wouldn't sand raise thermal conductivity significantly, without strength benefit?  Summertime seems challenging, with sand forcing measurable ice melt / sublimation on the columns, on those days when the surface regolith (sand) can exceed 20 C.

As for the magnetosphere, are you considering the notional balloon-encapsulated variant on Bamford et al. (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1604130#msg1604130), or something else?  If you go with an encapsulated form, can you add such a form to the illustration?  Should be a conversation-piece:  "Oz Beneath the Magnetic Cloud of Protection".   ;)
I'll go with SGHill's brilliant "the towers are an electrode". They are grounded at a ring all around the living area.  As the towers are 1 km high, why not a 2 km ring, so about 12 km2 of protected area.
The dust plays the role or rock and the water of cement in this Martian Pycrete.  We can paint the towers so they don't get too hot, and perhaps avoid this design in the areas that actually get a bit hot in summer.  Thermal inertia should do the rest to keep these cold.  In needed, they can be replaced by steel columns, but this should be cheaper.  Admittedly, concrete vs steel is always controversial with my structural friends.  Just imagine the columns made of your favorite material, doesn't change the concept.
About 3 000 000 m2 or 30 000 000 ft2 for the complex.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 02:23 pm
Would the minimagnetosphere be visible at night, rather like aurorae in northern climates?  In particular during solar storms?  then it would really look like Oz!  I expect during the day sunlight will be much to strong, and the minimagnetosphere would be invisible?

The ring might be a number of grounded rods, not a physical ring made of regolith?  Is the tower the emitter/ioniser, or is it the other way around?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 02:33 pm
Also, if you do go with some variation on Pykrete in the columns, you might consider adding ISRU gypsum to the ice, to lower thermal conductivity and give the ice a better chance of withstanding summer.  Mix some copper ions into the gypsum and you'll get the Oz coloration for your illustration.  L2!   8)

(https://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Gypsum-71006.jpg/314px-Gypsum-71006.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/29/2016 02:47 pm
Lar,

To be fair to Chris (Robotbeat), he wasn't actually talking about power production. That was just Wstewart insistently missing his point.



Don't want to live in holes?  Here is Megatower!
[...]

I like the audacity, but no. Unless there's an artificial constraint on outward expansion, tall buildings (especially super-tall buildings) are horribly inefficient. The volume required for internal transport alone would kill your concept.

However, if we're doing unlikely but interesting, how about a hanging-habitat. A giant, multi-kilometre single span "dome", with the habitats hanging vertically from the roof like icicles. Largest (longest) habitat at the centre, pulling the dome-roof down to create more of a pillow shape; with smaller habitats hanging around it, creating a dimple-pattern as they also weigh down the roof.

Spaced and aligned correctly, you should still be able to plant crops on the ground level without excessive shadowing from the hanging-habs.

Variation: A strip habitat. Similar to a tube-tunnel concept you did before, but on the surface. The bulk of the two strips of buildings providing the mass-anchor for the hemi-cylindrical roof spanning between them. Aligned east-west lengthways, with just enough leanback on the habitat-buildings to prevent shadowing during summer/winter solstice. (So as the equator, the habitat-buildings are symmetrically tilted 25° degrees away from the centreline. At 30° south, the northern strip is tilted 55° back, while the southern side can be vertical. (Hence the northern buildings are lower/smaller.) The east/west caps are quarter-spheres.

(Crude pic of the latter)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 03:08 pm
Lar,

To be fair to Chris (Robotbeat), he wasn't actually talking about power production. That was just Wstewart insistently missing his point.



Don't want to live in holes?  Here is Megatower!
[...]

I like the audacity, but no. Unless there's an artificial constraint on outward expansion, tall buildings (especially super-tall buildings) are horribly inefficient. The volume required for internal transport alone would kill your concept.

However, if we're doing unlikely but interesting, how about a hanging-habitat. A giant, multi-kilometre single span "dome", with the habitats hanging vertically from the roof like icicles. Largest (longest) habitat at the centre, pulling the dome-roof down to create more of a pillow shape; with smaller habitats hanging around it, creating a dimple-pattern as they also weigh down the roof.

Spaced and aligned correctly, you should still be able to plant crops on the ground level without excessive shadowing from the hanging-habs.

Variation: A strip habitat. Similar to a tube-tunnel concept you did before, but on the surface. The bulk of the two strips of buildings providing the mass-anchor for the hemi-cylindrical roof spanning between them. Aligned east-west lengthways, with just enough leanback on the habitat-buildings to prevent shadowing during summer/winter solstice. (So as the equator, the habitat-buildings are symmetrically tilted 25° degrees away from the centreline. At 30° south, the northern strip is tilted 55° back, while the southern side can be vertical. (Hence the northern buildings are lower/smaller.) The east/west caps are quarter-spheres.

Ha!  I was expecting that one!  The towers use the latest elevator technology from ThyssenKrupp
http://newatlas.com/thyssenkrupp-magnet-drive-elevator/34976/
to allow for multiple elevators in a single shaft, therefore reducing the transportation issues.  Actually not quite the latest, more like the slightly in the future...
The cylindrical shape reduces strain of the outer pressure membrane, exactly like vertical propane tanks you find in service centers. Horizontal circulation is also a space issue, at this scale, so I'm not convinced that kills the tall tower concept.
Now, the internal structure where people would actually live might be a problem.  I chose a 60m diameter because that can be subdivided into a 20m external ring, where you live, and a 20m core, for work, transportation and a rigid sway prevention construction.  It's probably a little wide, and a 40m cylinder might be more appropriate.

I like the idea of weighing down a dome with the habitat.  This reduces the strain on the attachments to the ground, since if it was perfectly balanced it no longer needs anchoring at all, but substitutes a requirement for a much stronger dome structures.  there might be an interesting compromise, with a dome supporting an internal donut type structure?  The donut would be supported like a suspension bridge by the dome.  I have my doubts we could be able to transmit the loads evenly, but perhaps if we had a lot of cables?  A kind of ring shaped suspension bridge!  But not certain this would be lighter than a tall tower.  alternatively, we could have a centrally supported cantilever structure that weights down on the edge of the dome.  Would have to be pretty thick though, but would give the living area structure a dual purpose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/29/2016 04:44 pm
Unless there's an artificial constraint on outward expansion, tall buildings (especially super-tall buildings) are horribly inefficient.
[...] The cylindrical shape reduces strain of the outer pressure membrane, exactly like vertical propane tanks you find in service centers.

But what is the advantage of going straight up compared to a similar structure parallel to the ground? There's effectively no limit to the length. Your buildings are impressive because they are 1km. A 1km long street of low buildings is, by contrast, considered trivial.

"Tall" only makes sense when land is limited. (Or when you're trying to project an image.)

Horizontal circulation is also a space issue, at this scale, so I'm not convinced that kills the tall tower concept.

It's a lot more energy efficient to move horizontally than vertically. Contrast walking along a flat path with climbing stairs in a building.

Also contrast how many people you can fit on a path, and how free you are (even when it's packed) to choose your own movement, compared to elevators in a building (even fancy neo-paternosters.)

I like the idea of weighing down a dome with the habitat. [...] but substitutes a requirement for a much stronger dome structures.  there might be an interesting compromise, with a dome supporting an internal donut type structure?

Hence the latter version. (Although semi-cylinderical, not a dome. Not very clear in my sad little cross-section. I'll admit, I was hoping you'd 3d it.)

I was also wondering about a ziggurat type structure, with bubble canopies around each row, with a small dome cap. The bulk of the structure is compressive (made from local materials, stone or sinter-crete), which provides the anchor-mass for the bubbles & cap.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 11/29/2016 05:33 pm
Did anyone mention a torus yet? Doesn't have the problems of lots of empty space like a dome, and with e small diameter, the pressure shouldn't be too high. Effectively the long thin horizontal structure from previous post, but with the ends joined together.

You could have concentric tori with a small dome in the middle. To make the 'city' bigger, add an extra torus round the outside.

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/29/2016 07:34 pm
But what is the advantage of going straight up compared to a similar structure parallel to the ground? There's effectively no limit to the length. Your buildings are impressive because they are 1km. A 1km long street of low buildings is, by contrast, considered trivial.

"Tall" only makes sense when land is limited. (Or when you're trying to project an image.)
I think projecting an image is one reason. IMO there are enough advantages to have at least some towers, if just to show what a tower on Mars can look like.

Possible advantages over horizontal cylinders.
*Better radiation protection (except for the top stories)
*Better views for the same window area. More panorama, less straight up: a direction we do not often look.

It might also be stronger as the weight helps resist pressure, and horizontal cylinders deal with varying directions of force based on pressure and bracing against varying ground. We might be able to design something that can be assembled floor by floor without cranes, in which case it is probably less fiddly to build a wider radius (say 50m) cylinder facing straight up than on the ground.

But sure. Cylinders on the ground will probably be our staple. Lots of advantages of these over towers too, such as being able to run for kilometers in a straight (or curved) line in a very natural possibly valley like environment. Could have a stream too.

(edit) Not directly on topic for towers, but I think wherever we live should encourage a fair bit of vertical movement. This would increase exercise and impacts. We can comfortably live in 2 story dwellings on earth, so maybe on mars we should aim for 5-6 story movement fairly common throughout the day.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/29/2016 07:54 pm
Charge and Discharge

The thin, ultra dry atmosphere will hold a massive charge that can be created using specially shaped towers and the martian wind (think huge van de graaff generators) connected by a huge loop antenna that encompasses the colony.

Hmm...  Harrison et al. 2016 (http://link.springer.com/article/10.1007/s11214-016-0241-8) notes the Tripathi et al. 2008 (http://home.iitk.ac.in/~snt/pdf/Space_Sc_Review.pdf) finding that the martian atmosphere's "electrical conductivity is usually two orders of magnitude greater than that for Earth".  And Youngquist 2009 (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090022229.pdf) worries about his proposed shield's "difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge [emphasis added]." 

And that's in the space environment, with negligible electrical conductivity.   

Earth's atmosphere has higher electrical conductivity. 

And Mars, 2 orders of magnitude higher than Earth (~ 10-10 Ohm-1m-1).

Generally speaking, higher conductivity leads to faster electrical discharge.

So, question:  How to prevent rapid discharge (failure) of the shield on Mars?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2016 11:42 pm
Did anyone mention a torus yet? Doesn't have the problems of lots of empty space like a dome, and with e small diameter, the pressure shouldn't be too high. Effectively the long thin horizontal structure from previous post, but with the ends joined together.

You could have concentric tori with a small dome in the middle. To make the 'city' bigger, add an extra torus round the outside.

Here is a surface version of an earlier underground tunnel version of the city.  Construction goes on forever in a continuous motion, side connectors make cross connections easier.  In a way this is typical of many of the forums... ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 11/30/2016 12:19 am
I think a Ziggurat is interesting.  Gave it a go for fun.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/30/2016 12:28 am
Cutaway view of a Dome inside a dome.  The green dome would be tied down to the white dome using cables.  This reduces the anchoring required at the base of the green dome, spreading the load.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/30/2016 03:43 am
You can also have tension cables inside a single dome to spread the load. Much simpler than concentric domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/30/2016 10:44 am
Cutaway view of a Dome inside a dome.

The outer white dome could be terraced for growing. (Irrigate at the top for high-sun, high temp, tropical crops; lower sun temperate crops further down.) The outer ring of ground between the outer white dome and the green pressure dome could be for aquaculture/algae-growing/water-treatment&recovery/thermal-dampening. Livestock in the central area (along with general purpose open space). Hab, production/processing, and storage then goes between the two white domes, and under the inner white dome. (You might have production facilities, labs, storage, etc, between the domes, with living areas under the inner dome with views of the central area.

IMO, your design makes better use of the upper volume than a conventional dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/30/2016 11:22 am
The Obligatory Truncated Octahedron Stack

No one has said "truncated octahedron" yet.  So:

(https://lh3.googleusercontent.com/-Cnz6EsSKcNQ/T5_e46hGFTI/AAAAAAAAJds/bkfzmt_U4vI/s506/600px-HC-A4.png)

Or we can look at other polyhedral stacks, such as:

(https://maxwelldemon.files.wordpress.com/2012/03/cathedral.png) (https://maxwelldemon.com/2012/03/26/the-2x1-rectangle-and-domes/)

Pros of truncated octahedra:

- No tunneling.   ::)
- Few anchors.
- Modular, with typical geodesic flat-pack efficiencies. 
- Octahedron (maybe 5 m scale) approximates a sphere, for pressure-vessel mass-efficiency.
- Multi-level space-filling stacks further improve mass-efficiency.  Insulated pressure walls are installed on exterior rooms only.   Common walls would be thin and uninsulated, a bit like a beehive's efficient honeycomb interior.
- As settlement grows incrementally, exterior rooms are over-stacked to become interior rooms.  The over-stacked pressure panels are then replaced with thin interior panels, and the hab's net mass efficiency improves with growth.
- Top-level octahedra are modular roofing, filled with sand or water for alternating radiation shielding:  sand over sleeping quarters for max shielding, water over gardens and common areas, for light (maybe 50% transmission with transparent, lensed and reflective panels).
- Enlarged common area and garden "hollows" ~20 m scale should be feasible with supplemental open-frame truncated octahedra.

Cons:

- The usual geodesic issues, I guess. 
- Maybe just too dense and noisy.  Who really wants to live in a beehive?



Addendum:  A real-world example of space-filling polyhedric architecture, on similar scale:  Zvi Hecher’s Ramot Polin Housing Complex (http://inhabitat.com/zvi-hechers-hivelike-ramot-polin-housing-complex-is-an-ambitious-failed-experiment-in-israel/zvi-hecker-ramot-housing-1):

(http://assets.inhabitat.com/wp-content/blogs.dir/1/files/2013/12/Zvi-Hecker-Ramot-Housing-2.jpg)

Quote
The inhabitants had to deal with unusable interior walls, narrow balconies and problematic natural lighting, which rendered the complex unappealing to the middle class population.

And that kid's stereo, no doubt.

Theme and variation: Zvi Hecker's Polyhedric Architecture (http://www.zvihecker.com/projects/polyhedric_architecture-257-1.html)

And a bit of architectural math, explaining why one might want to stack truncated octahedra, generally:  Simplicity is Not Simple:  Tesselations in Modern Architecture (https://www.maa.org/sites/default/files/pdf/upload_library/22/Evans/september_2002_5.pdf)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 11/30/2016 05:02 pm
Don't want to live in holes?  Here is Megatower!

It seems that one has to presuppose that there is an advanced industrial society on Mars numbering in the hundreds of millions to be on topic in this thread.

Or is that just me? :)

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/30/2016 08:52 pm
Well I for one am certainly not a vast industrial society numbering in the millions  8)

The Obligatory Truncated Octahedron Stack
No one has said "truncated octahedron" yet.  So:
Im interested in space filling polyhedra approaches.
https://forum.nasaspaceflight.com/index.php?topic=41526.msg1611256#msg1611256

I also thought I had linked to this somewhere.. but couldn't find it:
https://en.wikipedia.org/wiki/Honeycomb_(geometry)

There are options other than truncated octrahedron, for example the simple cube or hexagonal cylinder like we are used to from isometric games. I mean you wouldn't actually use a cube with those huge flat faces, but your internal struts could be a cube and each face could bulge outwards, perhaps like interlocking spheres. Or maybe they actually are flat but reenforced with internal cables.

I think these could actually give very interesting internal volumes by removing some internal faces.

One problem is that it would be nice to have faces that could resist pressure failure on either side.

If you can solve this I think it is a very attractive idea. Start small and just keep growing while accumulating more shielding and more redundancy.

I don't think there is any loss of effectiveness from not having a large dome either. If each cell is comparable in efficiency to a sphere then the sum of them is comparable to the efficiency of a large sphere, at least if you only consider pressure vessel mass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/01/2016 12:07 am
Don't want to live in holes?  Here is Megatower!

It seems that one has to presuppose that there is an advanced industrial society on Mars numbering in the hundreds of millions to be on topic in this thread.

Or is that just me? :)
It's just you :-))
There are many example of smaller buildings in the thread, giant buildings just evolved recently.  Size is an easy way to produce an  amazing effect, and it's interesting that Mars will eventually allow for the construction of larger buildings than on Earth.  However, clever and small can be amazing as well.  It's just harder to do.

A very specific Mars problem is that buildings have to be either extremely heavy, meaning many meters thick, to be in compression, or they need to be tension structures, which is essentially reserved for vehicles on Earth, or a few rare specialty structures.  This impacts the construction in various ways that are being explored. 

The radiation protection function is also something that doesn't exist on Earth.  This may or may not be an absolute, as mini magnetospheres are a possible alternative to mass shielding, and they have been mentioned by Musk as a possible solution.

The question of direct solar vs indirect solar has been touched upon, but not explored in detail yet.  Is it better to create a large array of solar cells, and use electricity and artificial lighting to grow plants in constant and controlled conditions, or to use greenhouses dedicated to plants or use a mixed construction, that integrates food production with habitat? Do these solutions change with latitude, as they do on Earth?



Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/01/2016 03:34 am
Problems in Xtreme Tinkertoy

There are options other than truncated octrahedron, for example the simple cube or hexagonal cylinder...

Sure, I was just noting its useful properties.  For example, having highest volume to surface area could save some cargo mass (11% relative to cubes).

I think these could actually give very interesting internal volumes by removing some internal faces.

One problem is that it would be nice to have faces that could resist pressure failure on either side.

If you can solve this I think it is a very attractive idea. Start small and just keep growing while accumulating more shielding and more redundancy.

It's an old idea, but yeah, maybe its mass efficiency and shielded modular growth model can justify further thought.  Plus it looks better than a design-reference dirt pile.   ;) 

Thinking about materials: 

- Pressurized panels might be mm aluminum-lithium alloy, as on Orion. 

- Unpressurized exterior panels, like those on sand shield octahedra, could be thinner alloy. 

- Unpressurized interior panels could be ISRU high-density plastic.

- Lightly pressurized transparent panels, like those on water shield octahedra, might be 2x100 micron ETFE foil.  Garden 60 kPa pressure would counter each octahedron's water weight and 40 kPa interior pressure, to maintain a flat ETFE base panel for the sunlit water "ceiling". 

Low-mass panel materials like that, coupled to the geometric efficiencies, could make for a very mass-efficient system.  But of course the struts would be complex.  Struts and vertex connectors would have to be very cleverly designed, to enable easy pressure-vessel construction, panel replacement, high reliability, etc.  I suppose they'd also serve double-duty as modular universal conduits for air, water, power, etc.  Plus they'd have to handle a wide range of loads, as the facility goes through its various growth reconfigurations. 

That's not Tinkertoy easy, but it's not impossible, I think.

(https://libraries.mit.edu/digital-archives/files/2012/10/cropped-TinkerToy_computer_MIT.jpg) (http://museum.mit.edu/nom150/entries/1215)
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 12/01/2016 01:17 pm
Let's be real clear here.

"Domes" can't exist on Mars unless they are unpressurized.  There's no amount of downforce that's going to keep the air inside from "burping" out along the bottom like a gigantic whoopie cushion unless the dome is really a deformed sphere pressure vessel where the top is sealed to the bottom.

We've covered this in excruciating detail starting here:  https://forum.nasaspaceflight.com/index.php?topic=34667.msg1352100#msg1352100  and going on for about 15 pages. 

I'm particularly proud of my own post here: https://forum.nasaspaceflight.com/index.php?topic=34667.msg1355550#msg1355550

 ;D

The whole discussion is a pretty good read for those of you who weren't participating in the chatter back then.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/01/2016 01:44 pm
Let's be real clear here.

"Domes" can't exist on Mars unless they are unpressurized.  There's no amount of downforce that's going to keep the air inside from "burping" out along the bottom like a gigantic whoopie cushion unless the dome is really a deformed sphere pressure vessel where the top is sealed to the bottom.

We've covered this in excruciating detail...

Long thread, categorical statement.  Just curious: did you see any force-analysis issue previously that would "burp out" Thistle Dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608957#msg1608957)?   I haven't seen a force problem with the water seal myself.  It still seems workable through active pressure equalization.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/02/2016 03:39 am
The Red Sands Saloon, our motto:  Wipe yer damn feet!
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 12/02/2016 10:07 am
The Red Sands Saloon, our motto:  Wipe yer damn feet!

Make that concentric tori - avoid the pressure awkwardness at the corners.

http://www.toysrus.com/graphics/tru_prod_images/Imaginarium-Stacking-Ring--pTRU1-16548595dt.jpg
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/02/2016 10:56 am
The Red Sands Saloon, our motto:  Wipe yer damn feet!

Make that concentric tori - avoid the pressure awkwardness at the corners.

http://www.toysrus.com/graphics/tru_prod_images/Imaginarium-Stacking-Ring--pTRU1-16548595dt.jpg
Could be a bit tempting for some martian to come along and start playing Tower of Hanoi :)

There might not be a problem. It depends. The 4-sided structure is not that far off a set of spherically ended cylinders.

The space filling polyhedra approach could be an even more extreme example. There is no need for the overall shape to be a smoothly curving sphere, cylinder, torus etc if each cell is a good pressure volume shape. You could build up any shape sort of like in MineCraft, and it would not lose huge efficiency.

I don't think there is any loss of effectiveness from not having a large dome either. If each cell is comparable in efficiency to a sphere then the sum of them is comparable to the efficiency of a large sphere, at least if you only consider pressure vessel mass.
..that is due to pressure vessel mass scaling with volume not surface area. Larger domes and spheres do not give more efficiency than the same volume divided into smaller domes and spheres. I mean, within some moderate fraction. Obviously once you start joining all these smaller volumes they are no longer exactly pure spheres etc.

In the case of space filling polyhedra the strength is in an internal set of struts, sort of like an aerogel, not just in a mathematically optimal surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/02/2016 02:26 pm
The space filling polyhedra approach could be an even more extreme example. There is no need for the overall shape to be a smoothly curving sphere, cylinder, torus etc if each cell is a good pressure volume shape.

Is that still true once you start removing internal walls?

Quote
I don't think there is any loss of effectiveness from not having a large dome either.
..that is due to pressure vessel mass scaling with volume not surface area. Larger domes and spheres do not give more efficiency than the same volume divided into smaller domes and spheres.

However, the materials themselves have non-linear scaling effects. For example, there's a minimum size in shell thickness before you lose so much strength in every other direction that the structure can't be trusted. (Just as basalt or glass becomes a flexible fibre below a certain thickness instead of a rigid but brittle solid. Any rigid frame elements will turn to wet-noodles once the struts get thin enough.)

That would suggest there's an optimal diameter for any particular material (which will be smaller if we're using a space-frame vs a solid shell), above the point where the thin-shell effect is replaced by the bulk properties. Either the minimum size where you stop gaining any strength/mass advantages, or the smallest size large enough to be useful. Any larger than that, and you might as well use multiple units; any smaller and you run into scaling issues.

In the case of space filling polyhedra the strength is in an internal set of struts, sort of like an aerogel, not just in a mathematically optimal surface.

The "internal" frame also gives you somewhere to hang your living space from. That gives you more usable internal volume. Domes tend to waste space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/02/2016 05:40 pm
The Red Sands Saloon [...]
Make that concentric tori - avoid the pressure awkwardness at the corners.

That's my fault. I meant circular tiers when I suggested it, but called it a "ziggurat" which generally (always?) have square tiers.

http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614432#msg1614432 (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1614432#msg1614432)

[Woah, why did my first pic get 275 views? There's no scale-hidden detail. It makes sense with TripD and Lamontagne's cool 3d stuff, but why did over 200 people need to enlarge or download my crappy paint.net drawing? Normally it's less than ten for such a simple sketch, presumably people browsing on their phones. Feeling a bit weirded out and paranoid.]

The Red Sands Saloon, [...]

In addition to JamesH65 point that it's supposed to be round, my suggestion of a ziggurat assumed a fairly flat location. That back side will be in permanent shadow, the right side not much better.

If you were against a slope, a hill or crater-wall, you'd just build essentially one (flat) face of the ziggurat against the slope.

[That also makes the structure more scalable, you can add new tiers, as well as extend tiers. (One of the things I don't like about my suggest ziggurat, it would need to be completed before it can be pressurised. There's no ability to expand organically once it's done.)]

Additionally, remember the point of the ziggurat is that the rock/sincrete structure serves as the anchor mass for the pressure vessel(s). Hence both the toruses and cap-dome must have an tangential angle of their anchors that points into the mass.

Hence the toruses need to be extend further out, more bubble-like, or else they will be trying to rip the edges off each tier.

Flip-side, the tangent of the anchors of the cap-dome only needs to match the angle of the overall structure, as long as it's set back far enough for the line to run through rock/etc from top-to-bottom.

[Nonetheless, I realised I screwed up. The whole point was that the ziggurat is also an occupied space. But pressurising a stone/sincrete structure puts all the load on the outer walls. The toroidal bubbles and cap-dome together function as if they were a single dome over the entire volume, allowing you to pressurise the whole ziggurat, but then the tiers allow (indeed require) the skin that anchors at that point to bubble outwards at a greater angle, creating the toroidal effect. But I realised later that the anchors for the toroids/dome have to lock the ziggurat together anyway. So there's no advantage in having the bubbles, except for creating a bit of open space outside each tier.]

[Edit: I also screwed up the conical anchor mass on the second image. The anchor-mass of a rock anchor is an upward facing cone. Still gives the general idea, hopefully.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/02/2016 06:26 pm
Quote
Hence the toruses need to be extend further out, more bubble-like, or else they will be trying to rip the edges off each tier.

Yah,  I have been assuming that all pressure response was built into the framework of the cylinders/partial spheres such that the square tiers were only there to provide easier architecture.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/02/2016 07:26 pm
Quote
Hence the toruses need to be extend further out, more bubble-like, or else they will be trying to rip the edges off each tier.
Yah,  I have been assuming that all pressure response was built into the framework of the cylinders/partial spheres such that the square tiers were only there to provide easier architecture.

My whole point of suggesting a ziggurat was that the structure serves as an anchor mass for the pseudo-dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/02/2016 10:55 pm
The space filling polyhedra approach could be an even more extreme example. There is no need for the overall shape to be a smoothly curving sphere, cylinder, torus etc if each cell is a good pressure volume shape.

Is that still true once you start removing internal walls?

No it does break down a bit: I did note that here:
Obviously once you start joining all these smaller volumes they are no longer exactly pure spheres etc.

However I am imagining most of the strength being in internal struts that would remain even when you remove internal walls. You are not trying to save on mass or strength or cost by removing these internal walls, just trying to make it easy to wander from cell to another. The only savings you could get is that internal struts might be cheaper than window for the same strength.

It is a different question whether you could have larger internal atriums without even these regular struts. Then the overall shape begins to become important again. I think you would consider these larger areas as a different embedded cell design entirely rather than just assuming you can begin omitting struts when 3 layers deep etc.

(about this idea, I like it but a big hole is that I don't know what internal walls that can take pressure loss from either side would look like)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/03/2016 03:27 pm
I don't think there is any loss of effectiveness from not having a large dome either. If each cell is comparable in efficiency to a sphere then the sum of them is comparable to the efficiency of a large sphere, at least if you only consider pressure vessel mass.
..that is due to pressure vessel mass scaling with volume not surface area. Larger domes and spheres do not give more efficiency than the same volume divided into smaller domes and spheres.

The radiation shielding doesn't scale with volume. That is obvious for passive shielding, but to my knowledge also holds for magnetic shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/03/2016 10:27 pm
The radiation shielding doesn't scale with volume. That is obvious for passive shielding, but to my knowledge also holds for magnetic shielding.
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes. Or underground but that is way off topic. Minimising heat loss might be a reason to keep things dome-like.

My point was only that cellular design could let you build to all sorts of shapes when considering pressure vessel cost. Of course there are other design factors that will affect what shape you choose, and a cellular design lets you pursue them.

Simplistically, you probably do pay a bit more for the cellular approach vs perfect spherical vessels. This is equivalent to whatever the structural mass is for a single cell compared to a perfect sphere of the same volume. But manufacturing giant spheres that cannot be used until completion and have no redundant protection also have costs and disadvantages. You also can't build different radii without different wall thicknesses. My guess is that a cellular design ends up cheaper.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/05/2016 12:54 am
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes.

The optimal shape for passive shielding is a sphere (minimizes mass per shielded volume), the optimal shape for magnetic shielding is a torus, to my knowledge.

But manufacturing giant spheres that cannot be used until completion and have no redundant protection also have costs and disadvantages.

I would expect early colonists to live in large inflatable habitats covered with soil, not in giant transparent domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/05/2016 01:58 am
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes.

The optimal shape for passive shielding is a sphere (minimizes mass per shielded volume)...

For omnidirectional radiation, yes.  As in a tall tower, or in transit. 

Not the case at ground level of course, where the radiation of interest is directed downward.  In a circular surface plan, depression or excavated column, the optimal shape for shielding is a horizontal circle:  e.g., a shallow circular sandlot, pond or ice disk, overhead.  It's 1/4 the surface area of a sphere of same radius, and volume is not constrained by that radius.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DusanC on 12/10/2016 10:19 pm
IMHO inflatable half cylindrical structures are better, something like bubble insulated greenhouses:

(http://www.solarbubblebuild.com/bubble_greenhouse_test_cell/img/test_cell.jpg)

Upsides:
1. Lower mass/usable surface ratio- I emphasize this as domes have large unused volume above, if you want to use it you have to make additional construction and you block sunlight;
2. Easier construction;
3. You can make segments easier so that damage in one segment doesn't depressurize everything;
4. Easier to expand;

Active bubble foam insulation between double outer wall is a great way to manage temperature, it works like this:

(http://www.solaripedia.com/images/large/2413.gif)
NOTE: Pictures above are just to show the idea of active bubble insulation, pictures from the web, not real Mars module design.

IMHO large number of standardized inflatable modules with active bubble insulation will be the way to go.
They will be built over and under ice as it would be easy to melt ice and make tunnels in it for under ice sleeping quarters that would be filled with these segments. Segments on ice would be half way immersed in it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/15/2016 11:42 am
I might be missing your point, but radiation shielding would be an argument to go away from domes and perhaps to more tower-like shapes.

The optimal shape for passive shielding is a sphere (minimizes mass per shielded volume)...

For omnidirectional radiation, yes.  As in a tall tower, or in transit. 

Not the case at ground level of course, where the radiation of interest is directed downward.  In a circular surface plan, depression or excavated column, the optimal shape for shielding is a horizontal circle:  e.g., a shallow circular sandlot, pond or ice disk, overhead.  It's 1/4 the surface area of a sphere of same radius, and volume is not constrained by that radius.

I would say the optimal pressure vessel defines the shape of the habitat (i.e. sphere or cylinder), then it is scaled up to a size where line of sights are sufficiently long and shielding becomes a relatively minor issue.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/17/2016 10:54 pm
As we've concluded many times in this thread, boring tunnels is and are actually the obvious solution for the second stage of living on Mars (the first stage being living in the lander and pre-fabricated modules). Preferably there would also be an ISS-style cupola on the surface for those rare moments when the crew has a few minutes of free time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/17/2016 11:21 pm
Tunnel boring machines on Mars to create mostly underground cities.

Hyperloops to connect the Martian cities.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/17/2016 11:24 pm
As we've concluded many times in this thread, boring tunnels is and are actually the obvious solution for the second stage of living on Mars (the first stage being living in the lander and pre-fabricated modules). Preferably there would also be an ISS-style cupola on the surface for those rare moments when the crew has a few minutes of free time.
Nah, that's not what Musk envisions. He wants people to live in the glass domes with tunnels for industrial areas. It's what he's said in the past, and it is a lot more attractive, as long as you're not paranoid about radiation. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/18/2016 04:18 am
Also for large spaces, TBMs might not be the right solution.

I was highly impressed by that salt mine shown upthread, and it might be a lot easier to mine such spaces using more conventional mining machines, or maybe even pressurized water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/18/2016 05:06 am

Tunneling is essential for something like Hyperloop to work out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/18/2016 05:57 am
Tunneling is essential for something like Hyperloop to work out.
I think you would put a hyperloop above ground. It would be cheaper and the key advantages to underground (radiation and robust sea-level pressure containment) are not issues.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 12/18/2016 12:27 pm
The inhabitants had to deal with unusable interior walls, narrow balconies and problematic natural lighting, which rendered the complex unappealing to the middle class population.

A classic case of architect failing to understand that people are in fact expected to live in the buildings he designs.

Who would've thought that people would need to install the usual rectangular cupboards, beds, sofas, shelves, bathtubs in their homes? That rectangular window panes are far easier to come by than pentagonal?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/18/2016 01:10 pm
Tunneling is essential for something like Hyperloop to work out.
I think you would put a hyperloop above ground. It would be cheaper and the key advantages to underground (radiation and robust sea-level pressure containment) are not issues.

Passenger comfort at such high speeds dictates straight tracks and the tracks will connect city centers respectively densely populated areas. Both will lead to lots of tunneling. Which isn't too bad though with a vactrain because the tunnel diameter can be smaller than with normal trains.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/18/2016 01:19 pm
The inhabitants had to deal with unusable interior walls, narrow balconies and problematic natural lighting, which rendered the complex unappealing to the middle class population.

A classic case of architect failing to understand that people are in fact expected to live in the buildings he designs.

Who would've thought that people would need to install the usual rectangular cupboards, beds, sofas, shelves, bathtubs in their homes? That rectangular window panes are far easier to come by than pentagonal?
Quite true. This is why domes work okay if very large but are terrible if they're small. The "edge effect" of trying to fit rectangular shapes inside a circular cross section (or the 3D analogues of each) becomes less problematic for large domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 12/18/2016 01:20 pm
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/18/2016 04:18 pm
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.

The only upfront convenience I can see is that a tunnel would mitigate dust issues.  Otherwise, it is possible that Mars would offer less atmospheric pressure than the earthbound hyperloop tunnels will have.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/18/2016 07:45 pm
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.

The only upfront convenience I can see is that a tunnel would mitigate dust issues.  Otherwise, it is possible that Mars would offer less atmospheric pressure than the earthbound hyperloop tunnels will have.
The biggest advantage of underground is thermal stability....

But hey - it'll be a while before you need rapid mass transport between Martian cities, something that rovers can't do...



Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/18/2016 07:53 pm
Passenger comfort at such high speeds dictates straight tracks and the tracks will connect city centers respectively densely populated areas. Both will lead to lots of tunneling. Which isn't too bad though with a vactrain because the tunnel diameter can be smaller than with normal trains.
Even if you disagree with Musk, this is a spaceX forum and he has clearly stated industry underground and living on the surface. From context Im not clear he did not just mean parks, rather than actually sleeping there, but obviously this makes it reasonable to have the place where you dock the hyperloop to visit another city on the surface.

Besides, there would be an acceleration and deceleration phase. If you had a hyperloop to something hundreds of kilometers away and your city was primarily underground, very little of the loop would have to be underground. A tiny fraction compared to the mined out volume of the city itself.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/18/2016 11:49 pm
Tunneling is essential for something like Hyperloop to work out.
I think you would put a hyperloop above ground. It would be cheaper and the key advantages to underground (radiation and robust sea-level pressure containment) are not issues.

Musk is all about creating disruption in established markets and economies. His method is always to rethink things to bring down the cost of a  given product/service drastically. What if he has an idea that would bring down the cost of tunnelling to a tenth or a twentyfifth of the present costs? Cheap tunnelling looks very attractive in the many areas of the world where the surface is already overdeveloped. An L.A. to S.F. hyperloop buried the whole way would avoid a lot of expropriation and land use costs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/19/2016 12:50 am
Would you even need a tube as Mars atmosphere is only 0.6% the pressure of Earths.
The only upfront convenience I can see is that a tunnel would mitigate dust issues.

Even then you only need a light-weight cover on an overland track. (Much much lighter than the lining for an excavated tunnel.)

But a hyperloop-type vehicle shouldn't experience dust issues. It doesn't ride on the "tracks" except for a short stretch at beginning and end (which can be easily maintained or covered). A thin layer of dust won't effect the levitation ability of the vehicle, and any over-pressure ground-effect system will (conveniently) blow away dust as the vehicle passes, so it won't accumulate. (Unlike on Earth, you can't get large movement of sand/dust in a single storm. The Martian atmosphere just physically doesn't have the carrying capacity.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/19/2016 04:27 pm
I don't understand the proposal - are you taking about a tube-less hyperloop?  That's impossible....
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/19/2016 04:52 pm
With the very low atmospheric pressure on Mars, hyperloop technology is not needed. Just build a maglev train, monorail, etc.

Tunneling is a very slow and difficult process. The machines are extremely large. First build on the surface, then when the base has the industrial capacity to build the main structure of the tunneling machine, send the harder to build parts from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/19/2016 06:11 pm
I'd add that maintenance/emergency access would be easier on an outside track.  More so if the tunnel is the cause of the issue.

Edit:  some clarity needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/19/2016 06:44 pm
With the very low atmospheric pressure on Mars, hyperloop technology is not needed. Just build a maglev train, monorail, etc.

Tunneling is a very slow and difficult process. The machines are extremely large. First build on the surface, then when the base has the industrial capacity to build the main structure of the tunneling machine, send the harder to build parts from Earth.
I thought the ram compression of the Mars atmosphere might make for a nice little air cushion system? Hyperloop operates at 1 millibar https://en.wikipedia.org/wiki/Hyperloop
and Mars atmospheric pressure is 6 millibar https://en.wikipedia.org/wiki/Atmosphere_of_Mars

It might save construction costs on the un-accelerated parts of the tracks and be used for propulsion?  Don't really need to worry about noise on Mars.
Don't see any point in tunneling for a Mars hyperloop at least for a few centuries.  But if we have underground cave habitats, then perhaps underground stations as well.

If Mars lighting under a dome is insufficient to grow plants in an intensive way, and if dome constructions costs are too high, might we just make very large solar arrays and grow everything underground?  After all, agriculture is also an industrial process, in a way, so we would not be going against a Musk quote.  A true food production dome is probably not a very comfortable environment, as anyone who has visited a green house will tell you.  Too humid and too bright.
After all the least effective part of a greenhouse with electric lighting will be the photosynthesis.  We might use the power losses in the power system to heat the colony.  Does photosynthesis scale linearly with lighting levels?

Lots of questions still, before we can design the habitat....
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/19/2016 06:58 pm
We haven't talked much about getting about in the habitat, in particular once it reaches more than a few thousand people.  Will walking be the only option?  How about vacuum tube transportation systems for small to mid size items?  These are notoriously unreliable on Earth, but might make sense on Mars, where there is ample supply of near vacuum.

If we go for an hyperloop for long distance, and we base our designs on the capacity of SpaceX, can we expect anything else than self driving people movers for all the larger distance, than combine up into an hyperloop vehicle as per this Dubai concept?

https://www.youtube.com/watch?v=fze5spdN3nU

Of course, exercise is good for you, perhaps in particular at 1/3g.  So people movers might be actively discouraged.

And what about air treatment?  Should this be centralized or distributed? And water?  Distributed seems safer, but usually large central plants are more efficient.

On the third hand, as the Moties would say, transportation is not really free, and youmight have a gain in promoting local usage.  Composting toilets, rather than our slightly mad water based system of today?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/19/2016 08:43 pm
(snip)
... But if we have underground cave habitats, then perhaps underground stations as well.

If Mars lighting under a dome is insufficient to grow plants in an intensive way, and if dome constructions costs are too high, might we just make very large solar arrays and grow everything underground?  After all, agriculture is also an industrial process, in a way, so we would not be going against a Musk quote.  A true food production dome is probably not a very comfortable environment, as anyone who has visited a green house will tell you.  Too humid and too bright.
After all the least effective part of a greenhouse with electric lighting will be the photosynthesis.  We might use the power losses in the power system to heat the colony.  Does photosynthesis scale linearly with lighting levels?

Lots of questions still, before we can design the habitat....

I agree with the insight about fields of solar panels and industrial "greenhouses" in caves and tunnels below. I think solar panels will be a better use of the surface than real greenhouses. Nuclear and solar, with fuel cell backup can share the power production responsibility. The LED-lit greenhouse caves with optimized wavelengths and optimized virtual day & night lengths etc. will then draw power from the grid. More efficient, more reliable and having flexibility with the sources & uses of power is always good for plan b's and plan c's.

If we expand the vision of caves under fields of solar panels to imagine what else is possible, I think that the imaginative use of multi-level landscapes will turn out to be important in the urban planning of amazing cities on Mars.

Landscapes filled with canyons, craters and mesas expose multiple horizontal and vertical surfaces. Multi-level landscapes make it easier to design an underground city that is not completely underground. Parts of caves can be exposed as domes on the south face of a crater wall, mesa or canyon, and parts of underground tunnels can be exposed and covered with geodesic structure & glass, mixing the indoor and outdoor experience as people move about the city. This way, people can spend most of a Sol in a fully underground zero radiation environment yet still have on-tap, frequent access to the exposed domes and exposed tunnels for eyeball contact with open vistas, the horizon, the great outdoors, the sun and wind, the dust devils, the human activity on the valley floor and the red or blue skies. I think the best uses of exposed domes will be public places for green parks, socializing and leisure, places of creative work, places of living (except sleeping) and the best uses of exposed tunnels would be to make walking or biking between points more interesting and uplifting. Caves and underground large tunnels would be best for industry, the radiation-safe portion of sleeping and living quarters, greenhouses and so forth.

Also, with multiple levels and a semi-underground city excavated in-between, things that should be above the city can be above it, such as the solar panel fields up top kept out of dust and shadow, or even landing pads, with easy vertical access down to the city, and things that should be below the city can be below, like the canyon floor that might be scoured for water- and mineral- bearing regolith, probably creating a regular local dust cloud in the process.

Finally, such landscapes also create natural protective divisions between areas, making it easier to zone nearby landing pads or nuclear power.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RanulfC on 12/21/2016 09:07 pm
On the third hand, as the Moties would say, transportation is not really free, and youmight have a gain in promoting local usage.

The correct terminology is "Gripping Hand" just FYI :)

Randy
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/22/2016 07:41 am
I envision a clear, one piece dome sited on top of a vertical, cylindrical shaft descending 5 or 6 levels down.  Each level has a terrace extending slightly further into the shaft than the one above until the lowest level is actually the shaft floor.  On the terraces are gardens, cafe, park and other common areas.  Radiating away from the shaft on each level are tunnels containing living and working areas, storage, utilities, medical, education etc.

The bigger the dome, the larger the terraces or the more numerous the levels.  Four horizontal tunnels per level spaced 90 degrees apart would be major thoroughfares with other areas/hallways branching off them.

Tunnels on level one would be at 12, 3, 6 & 9 o'clock.  Level two at 1, 4, 7 & 10 o'clock etc so that there is a vertical offset of 3 levels between the major spokes that would allow them to be joined by ramps for wheeled traffic at a suitable distance from the shaft.  Stairways and elevators could be put just about anywhere.

Smaller observation domes and airlocks would be at the far end of each spoke on level one.

How big a dome could that BFS carry ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 12/22/2016 07:14 pm
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/23/2016 07:13 am
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!
I have wondered whether you could inflate a sphere and then have a robotic sprayer in the center that slowly builds up layer after layer of a clear surface.

That does not sound very strong but suppose the sprayer had two parts: a fibre that it lays out in geodesics and a plastic of the exact same optical properties. The robotic sprayer could monitor the surface with incredible accuracy by laser interference.

This is just science fiction at the moment, but I can see that sort of technology progressing very rapidly. Once you get past the fact it is impossible it could become easy ;)

Even the inflatable part may seem incredibly naive in a decade or so. We may just print the thing.

Two interesting things to google:
* 3d printing polycarbonate
* 3d printing pen :)

It is amazing how this stuff is moving along and even becoming commonplace.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/23/2016 07:31 am
There's a story doing the rounds about an "igloo" concept for a 4-person Mars habitat called "Ice Home", coming out of NASA's Langley Research Center. (As distinct from the earlier "Ice House (http://payload409.cargocollective.com/1/12/384722/10487141/Mars-Ice-House_section_lr_1000.jpg)" concept that won the design challenge.)

[edit: It looks like the concept comes from many of the same people who developed the Ice House proposal. Space Exploration Architecture and Clouds Architecture Office, working with Langley.]

Space.com article (http://www.space.com/35101-mars-ice-home-design.html)

Daily-Fail article (http://www.dailymail.co.uk/sciencetech/article-4057680/The-ice-homes-Mars-Incredible-designs-reveal-frozen-habitats-one-day-call-home.html)

(Can't find anything at nasa.gov.)

Essentially it's a semi-transparent multi-layered inflatable habitat. A dome-like outer layer covers a toroidal pressurised habitat. The space between the toroidal hab and the outer dome is filled with ISRU-water and allowed to freeze. Between the skin of the toroidal hab and the ice is a pillow-like (or bubblewrap-like) layer which is pressurised with ISRU- CO2, which provides a cheap insulating air-gap between the hab and the outer dome.

(There might also be a liquid water layer between the CO2-bubblewrap and the habitat skin. Or I'm misreading the labels.)

Unlike many Mars hab concepts (for example (https://www.thesun.co.uk/wp-content/uploads/2016/11/nintchdbpict000281222478.jpg?w=960&strip=all)), they at least understand about pressure.

Some images:

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D31100000578-4057680-The_translucent_ice_layer_around_the_outside_of_the_pod_would_en-a-43_1482400185696.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D31100000578-4057680-The_translucent_ice_layer_around_the_outside_of_the_pod_would_en-a-43_1482400185696.jpg)

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30500000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-31_1482399958005.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30500000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-31_1482399958005.jpg)

(http://www.space.com/images/i/000/061/091/original/icehouse-4-inside.jpg?1482267946?interpolation=lanczos-none&downsize=*:1400) (http://www.space.com/images/i/000/061/091/original/icehouse-4-inside.jpg?1482267946?interpolation=lanczos-none&downsize=*:1400)

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30900000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-35_1482399958123.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30900000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-35_1482399958123.jpg)


The use of space is... odd. Tiny machine-room, even smaller greenhouse. Huge ward-room, "Library", "Study", etc. But that's fairly typical of these kinds of proposals.

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2F900000578-4057680-The_pods_would_include_areas_for_work_sleep_recreation_food_prep-a-30_1482399958004.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2F900000578-4057680-The_pods_would_include_areas_for_work_sleep_recreation_food_prep-a-30_1482399958004.jpg)

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2FD00000578-4057680-The_idea_is_that_the_Ice_Home_will_form_just_one_component_of_a_-a-37_1482399958155.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D2FD00000578-4057680-The_idea_is_that_the_Ice_Home_will_form_just_one_component_of_a_-a-37_1482399958155.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/23/2016 07:46 am
I have wondered whether you could inflate a sphere and then have a robotic sprayer in the center that slowly builds up layer after layer of a clear surface.

That was the idea behind the original "Ice House" 3d-printed concept.

(http://payload428.cargocollective.com/1/12/395831/10866388/19_Mars-Ice-House_deploy-bots-inner_07_670.jpg) (http://payload428.cargocollective.com/1/12/395831/10866388/19_Mars-Ice-House_deploy-bots-inner_07_670.jpg)

(http://www.rhinecapital.com/investmentinsights/wp-content/uploads/2015/10/Mars-Ice-House-Yard.jpg) (http://www.rhinecapital.com/investmentinsights/wp-content/uploads/2015/10/Mars-Ice-House-Yard.jpg)

http://greenbuildingelements.com/wp-content/uploads/2015/10/Ice-House-3.jpg (http://greenbuildingelements.com/wp-content/uploads/2015/10/Ice-House-3.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/24/2016 09:31 am
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!

Unfortunately I don't have the knowledge or software to do that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/24/2016 12:09 pm
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!

Unfortunately I don't have the knowledge or software to do that.

Ah, but I do!  So if you all want to flesh out the idea a little more, i'll be glad to give it a try!

But I agree we need a bigger dome for this to be an interesting habitat.  How large could an assembled dome be?  Let's suppose it gets held down by the mass of those terraces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/25/2016 10:56 am
If, as KelvinZero mentioned above, we could 3D print polycarbonate and a reasonable size dome could be made on site then let's pick a size to start with. Say 30 mt diameter.  Level one terrace extends 3 mt all around leaving 24 mt open.  Level two extends in another 4 mt leaving 16 mt and level three goes 5 mt leaving a 6 mt diameter floor in the center of level four order the dome.  The idea being that the higher the terrace, the more light it will receive therefore it needs less area under the dome.  Lower terraces are larger to capture more of the reduced light, if you get my drift.

Conversely if all terraces are set at 3 mt then you can have 5 levels under the same 30 mt dome.

Mick.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/25/2016 01:25 pm
You don't want to 3D print it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/25/2016 02:51 pm
If, as KelvinZero mentioned above, we could 3D print polycarbonate and a reasonable size dome could be made on site then let's pick a size to start with. Say 30 mt diameter.
To be clear I was not advocating any specific technology I am aware of today, such as existing polycarbonate 3d printing methods, just saying things are moving rapidly so schemes like relying on an inflated sphere to dictate your shape might seem very naive in the future.

3d printing might imply "building up dot by dot" also. My layman's guess is that if we went from a feedstock to a dome it would be more like cloth from spiderwebs than Minecraft. Just a guess though.

I think large monolithic clear domes is a worthwhile subtopic. Maybe other people can think of entirely different approaches to achieving this.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 12/25/2016 03:28 pm
Where would you get the polycarbonate feed stock from?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/25/2016 03:43 pm
Where would you get the polycarbonate feed stock from?

From Earth, of course. The feedstock would be very compact compared to the finished dome, so it and the printer system would easily fit in a BFS.

Once a colony is established, polycarbonate can be produced on Mars, but it's not going to be as easy to do as people think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/25/2016 04:44 pm
Don't 3D print it. Build it from pieces. If you 3D print it, it'll be weaker and only translucent, not transparent. And it'll take forever.

Don't 3D print it, especially if you're bringing the feedstock from Earth. Just because you CAN do something doesn't mean you should.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/25/2016 05:18 pm
Don't 3D print it. Build it from pieces. If you 3D print it, it'll be weaker and only translucent, not transparent. And it'll take forever.

Don't 3D print it, especially if you're bringing the feedstock from Earth. Just because you CAN do something doesn't mean you should.

Good point. Use the right tool for the job.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/25/2016 08:02 pm
OK.  I'm cool with a sectional dome. In this case it is primarily there to let in light and hold in air, not to provide living area.  I don't want to get into the geodesic discussion again.  Is there some other method of on site fabrication that could be used ?  What about spiral wrap off a roll and laser fuse the joints and cap it with a one piece section at the top ?

Mick
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/26/2016 03:22 am
Don't 3D print it. Build it from pieces. If you 3D print it, it'll be weaker and only translucent, not transparent. And it'll take forever.

Don't 3D print it, especially if you're bringing the feedstock from Earth. Just because you CAN do something doesn't mean you should.
I think you have some specific current day 3d printing technology in mind. Im not arguing anything to replace current payloads, or even Elon Musk's concept of assembling pressure tight geodesic domes from faces, though that is also not a space-ready technology as far as I know.

If we are discussing "What technology are we confident with today" then sure, this is ruled out. If we are discussing how to produce a monolithic dome with no crisscross of seams interfering with the view, then assembly from parts may be ruled out. They are different but valid things to discuss.

I think producing a dome from feedstock in one monolithic piece has the potential to be:
* stronger, due to no joins.
* not horribly slow, because one spraying machine can build up the entire surface in sweeps.
* Potentially easier to assemble robotically, so the time to assemble may matter less
* Perfectly transparent (because we are not talking of any specific technology. Also it would not be too hard to add a polishing phase)
* a more pleasing final result, without the cage of seams.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/26/2016 07:03 am
BFS as envisioned in the SpaceX video could not carry a dome larger than about 3 meters in diameter, limited by the cargo door size. Even with larger doors the 12m diameter is a pretty hard limit, so I doubt any domes will be transported in 1 piece.

I like the rest of your habitat ideas though. Would be cool to see a visual representation of it!

Unfortunately I don't have the knowledge or software to do that.

Ah, but I do!  So if you all want to flesh out the idea a little more, i'll be glad to give it a try!

But I agree we need a bigger dome for this to be an interesting habitat.  How large could an assembled dome be?  Let's suppose it gets held down by the mass of those terraces.

It is also possible to have a completely spherical dome, half-buried, with the underground stepped terraces integrated into the bottom half.

Alternatively, the spherical dome can be half-buried vertically into a natural vertical wall (e.g. mesa, canyon) with the stepped terraces arranged like theatre stalls so that they all have panoramic views of the outdoors.

The dome would therefore divide the terraces at all levels into two parts, one inside the dome and one outside.

Interesting (and I think on the whole beneficial) form and function consequences would follow...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 08:16 am
I know this thread is called "Envisioning Amazing Martian Habitats" but I still think that all these dome concepts and ideas are only valid for the far-off future. The early Mars years will be about survival and gaining a fooothold rather than grandeur. Pre-fab habitats and tunnels more than domes and ice sculptures.

Why domes? - To get light it is much easier to deploy solar panels and indoor lighting. For the view? - An ISS-style cupola should suffice. On the ISS they are more than happy to have the cupola for the few moments they can steal away from essential work. It has an ever-changing view unlike a Martian cupola where I can well imagine that the arid views will get old after a while.

Tunnelling provides radiation protection, provides a pressurized interior and provides an expansion potential only limited by the excavation equipment. The "building material" is already there: removing it is the issue, not bringing it from Earth.

A tunneling machine which can also solidify the walls is really the way forward for the early post-pre-fab period. A single machine that can be repaired with 3D printed parts. It would provide a habitat expanding in size daily, with exactly the ground plan needed, free of specific pressure vessel shape limitations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: paolopaolo on 12/26/2016 09:28 am
right, and probably is not necessary to dig tunnels. There may be lava tunnel that would be perfect. Just a note: I believe that the views of Mars will be wonderful
http://www.lpi.usra.edu/decadal/leag/AndrewWDagaFINAL.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 11:48 am
Alternatively, the spherical dome can be half-buried vertically into a natural vertical wall (e.g. mesa, canyon) with the stepped terraces arranged like theatre stalls so that they all have panoramic views of the outdoors.

If you are building against a linear wall, I wouldn't use a spherical structure, but a cylindrical one. (Rounded ends, obviously.) It allows more natural expansion, instead of having to demolish and rebuild the dome every time you want to expand, you just add another identical section to the end to lengthen it. The old end-caps become the safety barriers between sections.

right, and probably is not necessary to dig tunnels. There may be lava tunnel that would be perfect.

As the article notes, the problem is that the best lava tubes probably don't correlate with the best sites for other features like water.

(The ideal would be a lava tube that has collected water (and other volatiles) from prior warm periods, obviously. But it's unlikely to be an early find.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 11:50 am
that can be repaired with 3D printed parts.

We shouldn't assume that 3d-printing (or nano-tech, or bio-tech) will develop to that level. The risk is that you end up using it as "handwavium" to solve any problem. Technology as magic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 11:51 am
I agree that lava tubes are exciting and have the promise of huge interior spaces. But there are also many problems. You can't choose your location freely. If you dig your own tunnels you can place them optimally in close proximity to resources.

The structural soundness of lava tubes is also probably more difficult to ascertain than the integrity of drilled tunnels.

The access and entry of a lava tube may very well be difficult. Tunnels can be drilled into the side of a well-located hill or somewhere else which is practical.

Finally you can create the optimal layout if you do your own excavated tunnel system. Corridors, rooms, even huge halls (with support made out of un-excavated columns/cylinders), compartmentalized for maximum safety, should all be rather straightforward.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 12:08 pm
The structural soundness of lava tubes is also probably more difficult to ascertain than the integrity of drilled tunnels.

It would be exactly the same as assessing a site for drilling (except that you have access to inside the rock.)

The access and entry of a lava tube may very well be difficult. Tunnels can be drilled into the side of a well-located hill or somewhere else which is practical.

Can't see the logic of that. If you are comparing with tunnelling out the entire habitat, you can surely drill a short accessway to the main lava tunnel wherever it's convenient for you.

Finally you can create the optimal layout if you do your own excavated tunnel system. Corridors, rooms, even huge halls (with support made out of un-excavated columns/cylinders), compartmentalized for maximum safety, should all be rather straightforward.

There are holes into lava tubes that are hundreds of metres across. Some rill features are over a kilometre across and thousands of kilometres long.

Space is not going to be an issue.

As for "compartmentalising", you still need to build your actual habitat inside the lava tube. I doubt you would simply pressurise the raw tunnel. (Likewise for excavated tunnels, you are going to line the walls.)

--

IMO, the only issue with lava tunnels is that you don't get to choose the site. But that also holds true, if to a lesser extent, with excavated tunnels. The ideal site to drill is likely not to be ice-rich. (Unless you are living under the ice, as KelvinZero proposes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/26/2016 12:15 pm
Tunnelling provides radiation protection, provides a pressurized interior and provides an expansion potential only limited by the excavation equipment. The "building material" is already there: removing it is the issue, not bringing it from Earth.

You need lots of concrete and steel to build a tunnel. At least on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 01:24 pm
You need lots of concrete and steel to build a tunnel. At least on Earth.

Not when you drill in bedrock. For rock of lesser density it could be possible to vitrify the tunnel sides and ceilings in lieu of lining. If they would want to tunnel through sand on Mars (I wouldn't know why) they could build brick arches made from the excavated material.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 07:44 pm
You need lots of concrete and steel to build a tunnel. At least on Earth.

Not when you drill in bedrock. For rock of lesser density, it could be possible to vitrify the tunnel sides and ceilings in lieu of lining. If they would want to tunnel through the sand on Mars (I wouldn't know why) they could build brick arches made from the excavated material.
Soft regolith like material can be fused into a solid using microwave, creating a glass /porcelain like thick walls that are air tight. Plus digging through the loose material is much easier than drilling excavating a tunnel in hard rock. The microwave option would make the excavation slower but would not require materials to be created to create the walls since the materials in place are used. Thus a digging machine vs a drilling machine would be an easier first "subterranean" emplacement of living and workspace for the colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 12/26/2016 07:50 pm
Soft regolith like material can be fused into a solid using microwave, creating a glass /porcelain like thick walls that are air tight.

I keep hearing that. I do wonder, if it is that easy why is it not used on earth?
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 07:57 pm
Soft regolith like material can be fused into a solid using microwave, creating a glass /porcelain like thick walls that are air tight.

I keep hearing that. I do wonder, if it is that easy why is it not used on earth?
Requires extreme low humidity and air pressure (near vacuum). Otherwise, the microwaves heat the moisture and atmosphere keeping the material from reaching the very high internal temperatures to cause fusing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 08:34 pm
Yes, it should be the perfect process for the Martian atmosphere. OldAtlasEGuy, do you have any good links that go deeper into the method? - My knowledge of it is pretty superficial (no pun intended).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 08:49 pm
The structural soundness of lava tubes is also probably more difficult to ascertain than the integrity of drilled tunnels.

It would be exactly the same as assessing a site for drilling (except that you have access to inside the rock.)

The access and entry of a lava tube may very well be difficult. Tunnels can be drilled into the side of a well-located hill or somewhere else which is practical.

Can't see the logic of that. If you are comparing with tunnelling out the entire habitat, you can surely drill a short accessway to the main lava tunnel wherever it's convenient for you.

Finally you can create the optimal layout if you do your own excavated tunnel system. Corridors, rooms, even huge halls (with support made out of un-excavated columns/cylinders), compartmentalized for maximum safety, should all be rather straightforward.

There are holes into lava tubes that are hundreds of metres across. Some rill features are over a kilometre across and thousands of kilometres long.

Space is not going to be an issue.

As for "compartmentalising", you still need to build your actual habitat inside the lava tube. I doubt you would simply pressurise the raw tunnel. (Likewise for excavated tunnels, you are going to line the walls.)

--

IMO, the only issue with lava tunnels is that you don't get to choose the site. But that also holds true, if to a lesser extent, with excavated tunnels. The ideal site to drill is likely not to be ice-rich. (Unless you are living under the ice, as KelvinZero proposes.)

Paul, wouldn't a team actually drilling through rock get a better knowledge of it than a team which is just exploring a lava tube? To my mind, in the first case the drilling team will get more info about possible hidden features in the rock.

Regarding drilling a short access-way to an already existing lava tube. Well, if you will need to bring drilling equipment along in any case when you aim to exploit a lava tube... - Doesn't that negate much of the advantage of using an already existing tube? I agree that lava tubes will most probably require drilling to be useful. So, the drilling equipment needs to go to Mars in any case.

My hope is that the drilled tunnels would indeed in themselves be the habitat. Without any separate habitat built inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 08:50 pm
Yes, it should be the perfect process for the Martian atmosphere. OldAtlasGuy, do you have any good links that go deeper into the method? - My knowledge of it is pretty superficial (no pun intended).
http://www.techbriefs.com/component/content/article/ntb/tech-briefs/physical-sciences/16856 (http://www.techbriefs.com/component/content/article/ntb/tech-briefs/physical-sciences/16856)

It only addresses Lunar regolith but should be applicable Mars regolith with adjustments based on the regolith makeup.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/26/2016 09:07 pm
Ah yes, I remember reading about that study. Thanks for the link! Would be really cool to have a rover going to Mars to microwave various soil types and see how their properties could be changed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/26/2016 09:40 pm
Ah yes, I remember reading about that study. Thanks for the link! Would be really cool to have a rover going to Mars to microwave various soil types and see how their properties could be changed.
For the test the study only used a 60W microwave. So with losses a systems that uses ~200W or less should be able to test assumptions with real Mars regolith. In some ways having Lunar regolith brought back has made things easier for the Lunar regolith investigations.

The study basics was that it is a usable capability but will require adjustment based on the actual makeup of the material being sintered (made into a block).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/26/2016 10:56 pm
wouldn't a team actually drilling through rock get a better knowledge of it than a team which is just exploring a lava tube? To my mind, in the first case the drilling team will get more info about possible hidden features in the rock.

By then you are already committed to the site.

My point was that surveying candidate lava tubes is not going to be more difficult than surveying potential tunnelling sites before you start tunnelling.

Regarding drilling a short access-way to an already existing lava tube. Well, if you will need to bring drilling equipment along in any case when you aim to exploit a lava tube... - Doesn't that negate much of the advantage of using an already existing tube?

Do you feel that building a door into an existing wall requires as much equipment and supplies as building an entire house?

Also digging down with an opening above (or digging a ramp) is easier than digging horizontally underground. And for horizontal tunnelling, it's necessary before the TBM can start operating anyway. TBM's can't self-insert, can't dig down. So you need to bring the entirely separate "entry digging" equipment in order to deploy your horizontal tunnelling machine. A lava tube only needs the "entry digging" equipment and can skip the giant, heavy, high-maintenance TBM.

Additionally, digging an accessway into a lava-tube is going to be a hell of lot quicker than tunnelling the entire habitat volume. It means you can get established much quicker, which then allows you to turn that manpower, electrical power, supplies and equipment to other tasks, like ISRU "mining".

(There are lava-tubes with existing openings, of course, but I'm assuming the ideal site will end up being a sealed section.)

My hope is that the drilled tunnels would indeed in themselves be the habitat. Without any separate habitat built inside.

I'm not aware of any modern heavily-used tunnel on Earth which isn't lined/cased. Casing is usually built into the horizontal tunnelling process.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/27/2016 07:31 am
TBM's are too restricted in their range of movement.  Great for straight or slightly curved circular tunnels.  Use a Roadheader.  Excavates a relatively flat floor and can change direction easily and quickly.  Can be used to dig from scratch or to enter caves, lava tubes etc.

Mick
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/27/2016 01:07 pm
TBM's are too restricted in their range of movement.  Great for straight or slightly curved circular tunnels.  Use a Roadheader.

I was using "TBM" in the most generic sense of any dedicated tunnelling machine.

However, AIUI, roadheaders are also limited in how much they can dig down. If you are cutting into the side of a crater or hill-face, say, they would work fine. But when you were starting from relatively level ground and need to cut down to the level of the tunnel, you need to use other means to cut a ramp and start them off with an appropriate cutting-face. (Say hydraulic breaker/hammer.) And the method you use to create the starting surface for the roadheader is the entirety of gaining entry to a lava tube. Which was my point.

[Hydraulic breakers are modular and can attach to a suitable backhoe or loader, which can then be used for scraping the debris. Multi-purpose machines seem more likely than single purpose ones. You are going to bring some kind of backhoe/bucket-loader machine anyway, you might as well bring a rock-breaking module for it.]

--

OTOH, if the method of extracting water requires conventional mining techniques, then the sheer amount of mining required will mean a surfeit of equipment of all types will be available for comparatively trivial tasks like digging out a habitat.

--

OTGH, even if you require exactly the same equipment for the two jobs (cutting an entry-way into a lava-tube vs digging habitat tunnel(s) from scratch) you will still be finished digging into a lava-tube before the hab-tunnel project has dug its first room. Hence the equipment is freed up to go back to mining work much much earlier.

Of course, that assumes a lava-tube is available near a source of water. Which, IMO, is the only real problem with lava-tubes. They aren't going to be where you need them to be.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/27/2016 01:38 pm
Let's don't forget cut and cover tunneling. Dig a ditch, build structure in ditch, and cover it up. Walls can be microwave fused or cylindrical structures can be placed in the ditch. No TBM required.

What happened to "amazing" habitats? This has turned into a construction technique discussion as opposed to architecture. In other words, let's talk more about what to do with tunnels instead of how to build them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/27/2016 04:51 pm
Let's don't forget cut and cover tunneling. Dig a ditch, build structure in ditch, and cover it up. Walls can be microwave fused or cylindrical structures can be placed in the ditch. No TBM required.

What happened to "amazing" habitats? This has turned into a construction technique discussion as opposed to architecture. In other words, let's talk more about what to do with tunnels instead of how to build them.

Actually the OP solicited ideas for amazing habitats and also asked what tools or supplies you would want to take to Mars to build them. To keep things real, as much as possible:

Quote
What kind of amazing, spacious habitats can we envision? What selection of habitat building components would you want in your flat-packed containers?

So discussion of methods that enable the construction of amazing habitats is on topic. Very interesting nuggets emerge from such discussions, like the suggestion upthread that fusing freshly carved rock with microwaves will be well suited to excavating underground habitats on Mars because of the low atmospheric pressure and humidity there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 12/27/2016 08:44 pm
Lets just say if the digging/tunnel device uses microwave sintering for the creation of thick structural walls it can also drag behind all the other internal structural manufacturing to make the flooring:
 - square removable flooring plates (looks like porcelain tile, can be made intentionally rough for foot trafic)
 - the supports for the flooring and compartments for under floor equipment and cable/piping runs
 - the movable walls panels for creating rooms in the tunnel
 - attachment points to the tunnel walls and overheads for heavy equipment placement

Basically one machine as it crawls makes everything to create a structurally complete habitat only requiring the addition of equipment, wiring, and plumbing.

These additional items are made by robots that perform additive (3D) manufacture of the rough structural internal components. Every so often it creates a structural atmospheric bulkhead/airlock that is then outfitted with the necessary equipment to support the tunnel maker before sealing the airlock to pressurize. Once a section is pressurized, the airlock is used to transport the excess material dug from the tunnel in airtight containers out back through the tunnel. The tunneling machine makes the containers as well but the carriage/wheels are reused and not made by the tunnel machine. Remember these machines only move centimeters per hour.

But at only 5 cm in 1 hour will make a structurally complete 30m of tunnel per month and 360m of tunnel in 1 Earth year. If the tunnel is 15m in diameter with 4 floors that adds ~40m^2 per 1m length of floor space, that is in 1 Earth year 14,400 m^2 of floor space. NOTE in an gravity field the primary concern is on floor space for living area. But for packed storage the concern is volume. In volume it is 63,000m^3. If each person is assigned 100m^2 for living space and an additional storage and common area space of 100m^2 per person then the one year of tunneling would provide space for 72 additional colonists. It would take only 10 tunneling machines to keep up with 1000 colonists arriving every synod.

A 30m diameter tunneling machine would produce at the 5cm/hr crawl rate, space for 800 colonists per tunneling machine per synod. 13 machines would provide room for 10,000 new colonists per synod. That is at 250 colonists per ITS, 40 ITS filled with colonists per synod.

Remember the power used is related to crawl speed. At these low craw speeds the power usage is moderate. With moderate power usage the heat rejection can be handled by moderate cooling and the heating of the excess regolith up to room temp so as it is transported through the pressurized tunnel back out of the habitat it does not cause problems. In the 15m diameter tunnel machine case, 9 (3mX2mx3m) containers of regolith is transported through the airlock and back down the tunnel every day. One container size of material is used for internal structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/28/2016 12:11 am
Radial and dome.  30m dome, 6m tunnel, 3m terrasses.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Terra Incognita on 12/28/2016 11:14 am
That's a nice one Lamontagne.

The two things that strike me about that structure is that you could include an outer circular tunnel linking all of the other tunnels. That would be important in the event of a dome pressure failure so that the tunnels weren't dependent on the dome as the only link to the other tunnels.

The second thing is that it is infinitely expandable only limited by terrain. You can repeat that structure again and again, all linked. You could eventually tunnel a tube network below it. As you improve your dome technology you can have a larger and larger domes.

It looks like a very practical structure that can be scaled as skills and technology improve.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/28/2016 02:35 pm
MickQ,

I was puzzled by the radial tunnels in the description. Looking at the Lamontagne's rendering (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1623589#msg1623589), I'm even more confused.

What's the point in having so many separate tunnels?

Using that layout, you can't use a tunnel until it's completed and the excavating equipment is removed (otherwise you're trying to get the excavators back past the equipment installed earlier in the tunnel.) That means that tunnels are a once-and-done space, they can't easily be expanded - unless you leave a full set of excavating equipment at the end of each tunnel.

Using an Archimedean spiral (with the main habitat at the centre) you can start using the early parts of the tunnel while still excavating from the end. Plus cross-linking between loops is easier that cross-linking those radial tunnels. For redundancy and safety a concentric double or triple spiral would work (although requiring two or three sets of equipment.)

(http://www.penninetaichi.co.uk/index_files/image10511.jpg) (http://www.penninetaichi.co.uk/index_files/image10511.jpg)

[Lamontagne, if that's a road-header inside your tunnel, then your tunnels should be hemi-cylindrical. Flat-floored half-pipes.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/28/2016 02:56 pm
Using that layout, you can't use a tunnel until it's completed and the excavating equipment is removed (otherwise you're trying to get the excavators back past the equipment installed earlier in the tunnel.) That means that tunnels are a once-and-done space, they can't easily be expanded - unless you leave a full set of excavating equipment at the end of each tunnel.

Those tunnels are not deep, so no need for specialized tunneling machines. Use the cut and cover technique. Dig trenches with excavating equipment, build pressure structure (could be made out of locally made sintered rock/regolith removed from the trench), fill in the trench.

If you still want to use mining equipment, angle up a ramp at the end of the tunnel and roll out on the surface. It would be a good idea to have a surface exit every so often.

Using an Archimedean spiral (with the main habitat at the centre) you can start using the early parts of the tunnel while still excavating from the end. Plus cross-linking between loops is easier that cross-linking those radial tunnels. For redundancy and safety a concentric double or triple spiral would work (although requiring two or three sets of equipment.)

A good idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/28/2016 03:27 pm
Using that layout, you can't use a tunnel until it's completed and the excavating equipment is removed (otherwise you're trying to get the excavators back past the equipment installed earlier in the tunnel.) That means that tunnels are a once-and-done space, they can't easily be expanded - unless you leave a full set of excavating equipment at the end of each tunnel.

Those tunnels are not deep, so no need for specialized tunneling machines. Use the cut and cover technique. Dig trenches with excavating equipment, build pressure structure (could be made out of locally made sintered rock/regolith removed from the trench), fill in the trench.

If you still want to use mining equipment, angle up a ramp at the end of the tunnel and roll out on the surface. It would be a good idea to have a surface exit every so often.

Using an Archimedean spiral (with the main habitat at the centre) you can start using the early parts of the tunnel while still excavating from the end. Plus cross-linking between loops is easier that cross-linking those radial tunnels. For redundancy and safety a concentric double or triple spiral would work (although requiring two or three sets of equipment.)

A good idea.

If trenching displaces a lot more material than the tunnel, then trenching may be more expensive.  I don't know where the cut off depth is for economical trenching vs digging.
I've proposed the spiral twice before ;-)   It never gets much enthusiasm, somehow.

The domed pit might be done as a Guggenheim museum spiral ramp.  Otherwise some hard rock mines have spiraling access tunnels.  The Guggenheim would be more elegant and create a nice central space.

Next iteration will have flat tunnel floors, if there is enough enthusiasm for a particular design.
It would be interesting to have a surface sintering machine.  I guess we might have a few tens of kW to work with, since we will be needing the power later for the habitat anyway.  The sintering would stabilize the rock wall and prevent leaks and spalling. The rock may have a certain amount of void space, specially if it is sandstone, so the sintering might include a densification of the material?

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/28/2016 03:58 pm
I thought the giant open space with pillars left on a square grid was much more suitable for all purposes.

Tunnels are for transport.  They are 1D.  You want a 2D floor space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/28/2016 07:44 pm
Lets just say if the digging/tunnel device uses microwave sintering for the creation of thick structural walls it can also drag behind all the other internal structural manufacturing to make the flooring:
 - square removable flooring plates (looks like porcelain tile, can be made intentionally rough for foot trafic)
 - the supports for the flooring and compartments for under floor equipment and cable/piping runs
 - the movable walls panels for creating rooms in the tunnel
 - attachment points to the tunnel walls and overheads for heavy equipment placement
Basically one machine as it crawls makes everything to create a structurally complete habitat only requiring the addition of equipment, wiring, and plumbing.
These additional items are made by robots that perform additive (3D) manufacture of the rough structural internal components. Every so often it creates a structural atmospheric bulkhead/airlock that is then outfitted with the necessary equipment to support the tunnel maker before sealing the airlock to pressurize.

Once again, we shouldn't treat 3d-printing as magic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/28/2016 08:45 pm
Lets just say if the digging/tunnel device uses microwave sintering for the creation of thick structural walls it can also drag behind all the other internal structural manufacturing to make the flooring:
 - square removable flooring plates (looks like porcelain tile, can be made intentionally rough for foot trafic)
 - the supports for the flooring and compartments for under floor equipment and cable/piping runs
 - the movable walls panels for creating rooms in the tunnel
 - attachment points to the tunnel walls and overheads for heavy equipment placement

Basically one machine as it crawls makes everything to create a structurally complete habitat only requiring the addition of equipment, wiring, and plumbing.

These additional items are made by robots that perform additive (3D) manufacture of the rough structural internal components. Every so often it creates a structural atmospheric bulkhead/airlock that is then outfitted with the necessary equipment to support the tunnel maker before sealing the airlock to pressurize. Once a section is pressurized, the airlock is used to transport the excess material dug from the tunnel in airtight containers out back through the tunnel. The tunneling machine makes the containers as well but the carriage/wheels are reused and not made by the tunnel machine. Remember these machines only move centimeters per hour.

But at only 5 cm in 1 hour will make a structurally complete 30m of tunnel per month and 360m of tunnel in 1 Earth year. If the tunnel is 15m in diameter with 4 floors that adds ~40m^2 per 1m length of floor space, that is in 1 Earth year 14,400 m^2 of floor space. NOTE in an gravity field the primary concern is on floor space for living area. But for packed storage the concern is volume. In volume it is 63,000m^3. If each person is assigned 100m^2 for living space and an additional storage and common area space of 100m^2 per person then the one year of tunneling would provide space for 72 additional colonists. It would take only 10 tunneling machines to keep up with 1000 colonists arriving every synod.

A 30m diameter tunneling machine would produce at the 5cm/hr crawl rate, space for 800 colonists per tunneling machine per synod. 13 machines would provide room for 10,000 new colonists per synod. That is at 250 colonists per ITS, 40 ITS filled with colonists per synod.

Remember the power used is related to crawl speed. At these low craw speeds the power usage is moderate. With moderate power usage the heat rejection can be handled by moderate cooling and the heating of the excess regolith up to room temp so as it is transported through the pressurized tunnel back out of the habitat it does not cause problems. In the 15m diameter tunnel machine case, 9 (3mX2mx3m) containers of regolith is transported through the airlock and back down the tunnel every day. One container size of material is used for internal structures.

Really fascinating calculations OldAtlasEGuy. Sounds like you have experience in tunnelling? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/28/2016 09:42 pm
How much does a 30 m TBM weigh?


Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

I think key to excavating is to find easy to remove soil (a salt deposit would be awesome) and create large caverns.

If the cavern is large, you need to worry a lot less about "wall finishing", which makes the process not efficient, and the TBM less suitable.

For transport, however, a 2-3 m TBM might be an efficient way to connect nearby structures to each other.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/28/2016 10:13 pm
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.

[Edit: You wouldn't want a true TBM. They aren't able to dig through loose material, for example. And are hideously difficult to do major repairs on, as anyone in Boston would be aware.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/28/2016 10:19 pm
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.
Yup, was trying to look that up.

They are optimized for the wrong type of problem - boring a straight narrow line through whatever adversity lies between points A and B.

We're looking for a nice large habitable volume, more like an underground parking garage, and place it where we choose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/29/2016 12:00 am
Quote
Those tunnels are not deep, so no need for specialized tunneling machines. Use the cut and cover technique. Dig trenches with excavating equipment, build pressure structure (could be made out of locally made sintered rock/regolith removed from the trench), fill in the trench.

This has the added benefit of allowing for processing the regolith before using to bury the structures.  Nice to know exactly what is over the top of you too.

Quote
I think key to excavating is to find easy to remove soil (a salt deposit would be awesome) and create large caverns.

Easy to remove is great for trenches.  Not nearly so great for tunnels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/29/2016 12:08 am
Quote
Those tunnels are not deep, so no need for specialized tunneling machines. Use the cut and cover technique. Dig trenches with excavating equipment, build pressure structure (could be made out of locally made sintered rock/regolith removed from the trench), fill in the trench.

This has the added benefit of allowing for processing the regolith before using to bury the structures.  Nice to know exactly what is over the top of you too.

Quote
I think key to excavating is to find easy to remove soil (a salt deposit would be awesome) and create large caverns.

Easy to remove is great for trenches.  Not nearly so great for tunnels.
I was commenting based on seeing those mined caverns.  Lots of volume, lots of floor space, less issues with smooth walls.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/29/2016 06:01 am
Re-posting (subtropolis)

https://en.wikipedia.org/wiki/SubTropolis?wprov=sfla1

http://www.zerohedge.com/news/2015-02-04/behold-subtropolis-underground-city-located-excavated-kansas-mine

~10,000,000 square feet, out of limestone.

On Mars, you'd mine one zone at a time, leaving walls in between acting like bulkheads.

Can have multiple floors for compactness

Can grow in all directions while occupied, and all dimensions are flexible.

Is there limestone on Mars?  Dunno. But pictures of salt mines look similar, and I'm pretty sure salt deposits exist.

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 12/29/2016 07:58 am
Is there limestone on Mars?  Dunno. But pictures of salt mines look similar, and I'm pretty sure salt deposits exist.

Limestone is built by corals, so probably none on Mars. Maybe other not so hard bedrock? Basalt is really hard and harsh on any mining or boring equipment. Any progress in mining that has less expendable tools like drillbits would be very welcome. Replacing them on Mars is a headache while not a problem on earth.

Salt deposits would be great. There may be enough for raw materials. But I doubt there will be big enough layers for habitat building. Salt did accumulate in earths oceans over a long time before such deposits happened. Too bad. I once visited a salt mine and the huge caverns were gorgeous.

Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/29/2016 10:25 am
Great rendering Lamontagne. Thanks.  My original thought was for the terraces to be full circles joining the ends of all tunnels on the same level under the dome.  Stairways and elevators would link different levels at suitable places and horizontal hallways join tunnels on the same level.  The tunnels are major thoroughfares for moving large volumes on wheels, so flat floors and the outer end of each tunnel is connected by a ramp up, and or down to the next adjacent tunnel one level up or down.  This is why the tunnels are offset vertically like a clock face.
Rooms, hallways etc would be dug off the main tunnels as required on each level.  I explained this in my post #603.

And, I use the term TUNNEL rather loosely.

Mick.
Title: Re: Envisioning Amazing Martian Habitats
Post by: llanitedave on 12/29/2016 03:51 pm
Is there limestone on Mars?  Dunno. But pictures of salt mines look similar, and I'm pretty sure salt deposits exist.

Limestone is built by corals, so probably none on Mars. Maybe other not so hard bedrock? Basalt is really hard and harsh on any mining or boring equipment. Any progress in mining that has less expendable tools like drillbits would be very welcome. Replacing them on Mars is a headache while not a problem on earth.

Salt deposits would be great. There may be enough for raw materials. But I doubt there will be big enough layers for habitat building. Salt did accumulate in earths oceans over a long time before such deposits happened. Too bad. I once visited a salt mine and the huge caverns were gorgeous.


Considering all the dust blowing around, the most common rock type is likely to be salt-cemented sandstone.  That should be fairly soft to work, but not particularly strong.  Before any of this gets underway, and before any detailed tunnel designs can be put together, there's going to have to be some fairly extensive rock mechanics studies at the proposed sites.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/29/2016 07:25 pm
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.

[Edit: You wouldn't want a true TBM. They aren't able to dig through loose material, for example. And are hideously difficult to do major repairs on, as anyone in Boston would be aware.]
My own guess is for a roadheader.  More flexible than a tunnel boring machine, and much lighter.  Requires service trucks to remove the minerals.
I've made a model of a for 3D renderings.  It's based on the Sandvik 300 and the Dosco 2.2
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/29/2016 07:29 pm
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.

[Edit: You wouldn't want a true TBM. They aren't able to dig through loose material, for example. And are hideously difficult to do major repairs on, as anyone in Boston would be aware.]
My own guess is for a roadheader.  More flexible than a tunnel boring machine, and much lighter.  Requires service trucks to remove the minerals.
I've made a model of a for 3D renderings.  It's based on the Sandvik 300 and the Dosco 2.2
Yeah, this looks much more practical, maintainable, and flexible.

If the rock is "salt cemented", would wetting it help reduce power requirements?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 12/29/2016 07:57 pm
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.

[Edit: You wouldn't want a true TBM. They aren't able to dig through loose material, for example. And are hideously difficult to do major repairs on, as anyone in Boston would be aware.]
My own guess is for a roadheader.  More flexible than a tunnel boring machine, and much lighter.  Requires service trucks to remove the minerals.
I've made a model of a for 3D renderings.  It's based on the Sandvik 300 and the Dosco 2.2
Yeah, this looks much more practical, maintainable, and flexible.

If the rock is "salt cemented", would wetting it help reduce power requirements?
How deep do the tunnels need to be?
I was thinking of digging trenches. Then placing the habitats in the trench. Followed by covering them with some of the removed material in layers by type best to block radiation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/29/2016 08:06 pm
How much does a 30 m TBM weigh?
Wiki says that a 15 m machine for rock weighs 4500 tons and eats 18 MW.

That's a true TBM, but there are other types of tunnelling machines.

That said, they're all pretty heavy. And require a whole ecosystem of support equipment not counted in the mass of the central machine.

[Edit: You wouldn't want a true TBM. They aren't able to dig through loose material, for example. And are hideously difficult to do major repairs on, as anyone in Boston would be aware.]
My own guess is for a roadheader.  More flexible than a tunnel boring machine, and much lighter.  Requires service trucks to remove the minerals.
I've made a model of a for 3D renderings.  It's based on the Sandvik 300 and the Dosco 2.2
Yeah, this looks much more practical, maintainable, and flexible.

If the rock is "salt cemented", would wetting it help reduce power requirements?
How deep do the tunnels need to be?
I was thinking of digging trenches. Then placing the habitats in the trench. Followed by covering them with some of the removed material in layers by type best to block radiation.
I can't judge which is better.

My thought was going horizontally into a hill side.  Why?  I don't know.

Maybe I initially keeping it level removes the need for ramps, elevators, etc.

Also if you go up at a slight angle, material removal doesn't take energy.

And you can use the removed material outside for whatever purpose.

Basically you can set up a gravity powered soil separation and processing plant, all inside your new cavern
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/29/2016 08:07 pm
A roadheader, a Volvo mining truck and a modified truck with a microwave sintering head.
The sintering head is a powerful microwave emitter, designed to melt the very dry rockface and transform it into a form of glass finish.  For air tightness, spalling reduction and easier construction.

The truck carries batteries, a power system and a cooling system.  All the equipment is battery powered with electrical drives.

The rubber tires would be replaced with a metal equivalent.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 12/29/2016 08:33 pm
{snip}
I can't judge which is better.

My thought was going horizontally into a hill side.  Why?  I don't know.

Maybe I initially keeping it level removes the need for ramps, elevators, etc.

Also if you go up at a slight angle, material removal doesn't take energy.

And you can use the removed material outside for whatever purpose.

Basically you can set up a gravity powered soil separation and processing plant, all inside your new cavern
A hill could offer a tall layer of material to block radiation. Habitats could be on the non direct Sun light side for less radiation from the Sun.

Or just level off an area and place habitats on it. Then use material near area to cover the habitats.

A roadheader, a Volvo mining truck and a modified truck with a microwave sintering head.
The sintering head is a powerful microwave emitter, designed to melt the very dry rockface and transform it into a form of glass finish.  For air tightness, spalling reduction and easier construction.

The truck carries batteries, a power system and a cooling system.  All the equipment is battery powered with electrical drives.

The rubber tires would be replaced with a metal equivalent.

How thick is this glass layer? Could it crack? Would the out layer of material ( rock , soil ) slow a leak long enough for crew to fix before to much air pressure is lost?

I like the idea. It could be used to hold water. Has there been a test of this idea with microwaves?
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 12/29/2016 08:43 pm

The rubber tires would be replaced with a metal equivalent.


Why would you need to do that? Metal tires aren't used here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/29/2016 08:44 pm
{snip}
I can't judge which is better.

My thought was going horizontally into a hill side.  Why?  I don't know.

Maybe I initially keeping it level removes the need for ramps, elevators, etc.

Also if you go up at a slight angle, material removal doesn't take energy.

And you can use the removed material outside for whatever purpose.

Basically you can set up a gravity powered soil separation and processing plant, all inside your new cavern
A hill could offer a tall layer of material to block radiation. Habitats could be on the non direct Sun light side for less radiation from the Sun.

Or just level off an area and place habitats on it. Then use material near area to cover the habitats.

A roadheader, a Volvo mining truck and a modified truck with a microwave sintering head.
The sintering head is a powerful microwave emitter, designed to melt the very dry rockface and transform it into a form of glass finish.  For air tightness, spalling reduction and easier construction.

The truck carries batteries, a power system and a cooling system.  All the equipment is battery powered with electrical drives.

The rubber tires would be replaced with a metal equivalent.

How thick is this glass layer? Could it crack? Would the out layer of material ( rock , soil ) slow a leak long enough for crew to fix before to much air pressure is lost?

I like the idea. It could be used to hold water. Has there been a test of this idea with microwaves?
Yes, with lunar soil. There are discussions further up thread and here is a paper.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/29/2016 08:47 pm

The rubber tires would be replaced with a metal equivalent.


Why would you need to do that? Metal tires aren't used here.
Bacause rubber at low temperature undergoes a glass phase transition.  https://en.wikipedia.org/wiki/Glass_transition

It's a long standing problem with rubber and other flexible materials.  Infra red heating of the tunnels as there were being built might mitigate this.  But don't let your truck out during the night, the tires will shatter!

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/29/2016 08:59 pm
Mars has an average surface temperature of -55C, which is slightly warmer than the typical winter temperatures of the interior of Antarctica. The Mars underground temperature will be warmer than the average surface temperature, so whatever works in Antarctica (temperature-wise) would be fine in tunnels on Mars. Tires are used in Antarctica. Metal tires not required.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/29/2016 09:17 pm
Mars has an average surface temperature of -55C, which is slightly warmer than the typical winter temperatures of the interior of Antarctica. The Mars underground temperature will be warmer than the average surface temperature, so whatever works in Antarctica (temperature-wise) would be fine in tunnels on Mars. Tires are used in Antarctica. Metal tires not required.
Perhaps.  But remember we use the trucks to move materials outside.  And we're not worried about average but about extremes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/29/2016 09:23 pm
You don't see those extremes underground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/29/2016 09:35 pm
The rubber tires would be replaced with a metal equivalent.
Why would you need to do that? Metal tires aren't used here.
Bacause rubber at low temperature undergoes a glass phase transition.

Actually the main reason is because rubber doesn't tolerate a vacuum for long periods. Volatile solvents/plasticisers outgas, leaving brittle remains.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/29/2016 09:39 pm
Once the cavern starts out, it'll be sealed of course...  So can be heated and pressurized.  I mean it's going to have to be, anyway...

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/29/2016 09:40 pm
Once the cavern starts out, it'll be sealed of course...  So can be heated and pressurized.  I mean it's going to have to be, anyway...

Rock isn't air-tight.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/29/2016 09:46 pm
Once the cavern starts out, it'll be sealed of course...  So can be heated and pressurized.  I mean it's going to have to be, anyway...

Rock isn't air-tight.
Deep enough, and I think you mostly have to worry about fissures/cracks.

And if there are so many that you can located then individually, the surface treatment can't be that difficult, mass wise.

And again, a cavern has less wall area per usable volume, compared with tunnels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/29/2016 09:54 pm
Rock isn't air-tight.
Deep enough, and I think you mostly have to worry about fissures/cracks.

And the wall that you are excavating. You can't seal a mine.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/29/2016 09:58 pm
Pressurized mining is a thing. It's almost certainly how you'd want to operate under Mars otherwise designing the equipment would cost a fortune and heat rejection a huge challenge.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/29/2016 10:15 pm
Pressurized mining is a thing.

Links?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oli on 12/29/2016 11:36 pm
Pressurized mining is a thing.

Links?

It's done to keep water out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: launchwatcher on 12/29/2016 11:50 pm
A roadheader, a Volvo mining truck and a modified truck with a microwave sintering head.
so the sintering truck has to drive all the way out of the tunnel to allow the mining truck to dump its load?
Seems like you'd do better by reordering the convoy and running a conveyor over the sintering truck.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/30/2016 12:01 am
How much air pressure are we talking about?  I am curious just how that would keep water out.
Edit/  With regards to earthbound operations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 12:20 am
How much air pressure are we talking about?  I am curious just how that would keep water out.
Edit/  With regards to earthbound operations.
Has to be equal to or a little greater than the water pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Nomadd on 12/30/2016 03:41 am
 Bill McGonigle's 13 year old daughter, Emma came up with this.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 12/30/2016 05:49 am
A roadheader, a Volvo mining truck and a modified truck with a microwave sintering head.
The sintering head is a powerful microwave emitter, designed to melt the very dry rockface and transform it into a form of glass finish.  For air tightness, spalling reduction and easier construction.
....

There is no need for the modified truck. Replaced with motorized trailer mounted version attached to the Roadheader with two sintering heads. Sintering head on each side of the trailer allows a conveyor belt in the middle for loading the dump truck. Of course, probably only one Sintering head is operational at any time. As a bonus the combine batteries on the Roadheader and trailer can can by use by either unit, plus the trailer with its battery can be replaced with a fully energized unit without the Roadheader requiring to egress for recharging.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 12:08 pm
How much air pressure are we talking about?  I am curious just how that would keep water out.
Edit/  With regards to earthbound operations.
Has to be equal to or a little greater than the water pressure.

Which is the point. Without the internal pressure, the inside is at lower pressure than the surrounding water and so water leaks into the mine. Raising the internal pressure enough to keep the water out isn't isn't actually pressurised in the sense you want for Mars, it's merely equalising pressure.  The water effectively creates a hydraulic seal, balancing the internal pressure, and vice-versa. Increase the internal pressure enough and air will leak out at a rate proportional to the pressure difference.

But Mars is a near vacuum. So pretty much any pressurisation means the air will leak out.

This is the same issue we've talked about with open-bottom domes. The ground will not hold the pressure, even if the dome itself is sufficiently anchored. You have to seal the floor.

If, however, you have examples of mines that pressurise above the surrounding water-head pressure, I'd love to see them. Perhaps someone using air (or fluid) overpressure as a pseudo-structural-support, in specific applications?

The only examples I am aware of are naturally pressurised wells, and the use of pressurised "mud" at a cutting face (which is prone to sudden pressure drops every time the fluid finds a new path out).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 12:43 pm
Yeah, it's not exactly the same as Mars. Obviously.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 12:55 pm
Yeah, it's not exactly the same as Mars. Obviously.

So you can't pressurise a mine or underground excavation on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 01:08 pm
Yeah, it's not exactly the same as Mars. Obviously.

So you can't pressurise a mine or underground excavation on Mars.
Yes you can.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 01:14 pm
Yeah, it's not exactly the same as Mars. Obviously.
So you can't pressurise a mine or underground excavation on Mars.
Yes you can.

Links?
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 02:05 pm
There can be two ways that air could leak through meters of soil.  Either the soil is porous, or there are cracks/fissures in it.

You can deal with porosity with a sealant. It'll wick in a little bit, solidify, done.

Larger cracks need individual attention, like applying a filler, but I can't see this being a problem either.

This is assuming you'd get any leakage at all. You realize air is not going to be whooshing into the rock face, right?

Either way, I will expect some insulating foam to go on top (ceiling and walls), and some more complex flooring treatment for insulation, sealing, abrasion resistance.

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 02:23 pm
Yeah, it's not exactly the same as Mars. Obviously.
So you can't pressurise a mine or underground excavation on Mars.
Yes you can.

Links?
Look up any literature on underground CASES.

Their default solution (ha!) Is salt deposits, but also looking at  regular mines.

With all the evidence for past briny oceans, I think salt deposits will be there anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 02:24 pm
Yeah, it's not exactly the same as Mars. Obviously.
So you can't pressurise a mine or underground excavation on Mars.
Yes you can.

Links?
Links showing conclusively that you can't?
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 02:39 pm
Yeah, it's not exactly the same as Mars. Obviously.
So you can't pressurise a mine or underground excavation on Mars.
Yes you can.

Links?
Also, underground storage of pressurized natural gas

https://www.eia.gov/naturalgas

So between CAES and this, plenty evidence that it is possible, and now it's your turn to show why it isn't.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 05:06 pm
Either the soil is porous

Well, yes.

Either way, I will expect some insulating foam to go on top (ceiling and walls), and some more complex flooring treatment for insulation, sealing, abrasion resistance.

I was talking about a working mine. Robotbeat and others suggest that the work site will be under pressure.

I'm not saying you can't seal an excavated cavity afterwards. In fact I'm saying you have to. But you can't continue to dig from within that sealed space. Hence you can't seal a working mine.

(Unless you find a nice liquid water (hypersaline?) aquifer that creates a counter-pressure against the air-pressure.)

This is assuming you'd get any leakage at all. You realize air is not going to be whooshing into the rock face, right?

It's hard to find a comparison for Earthly mining, precisely because mines/caissons are only ever pressurised to balance water pressure, never to over-pressurise. So outward flow numbers are hard to find. Instead, using inwards flow of water as a proxy, at just one atmosphere of head-pressure from a surrounding water-table and typical wet-porosity of mine-altered hard rock (~0.15ft/d), a simple 200-foot wide rock pit 20-foot below the water table can experience tens of tons of water inflow per day.

Re: CAES/etc.

These require existing, naturally occurring capped sites. (And as I said before (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1624372#msg1624372), such naturally pressurised sites are the only examples I can find for "pressurisable".)

Usually deep underground, porous (uhh, hello!) rock under some kind of capstone layer. The porous layer is usually part of a saddle structure, reducing horizontal flow away from the storage site. Note that the rock that you are storing in is not the part that's sealed, it's the over-layer that's sealed. (Typically there'll be another aquifer above the impermeable layer, providing additional hydrostatic pressure. The aquifer also helps to "capillary seal" the capstone; it's harder for gas to flow through wet rock, since it has to displace the water from each porous capillary. Slows the leak rate.)

Hence it's important that you cause as little damage to the over-layer as possible. Non-porous rock tends to be brittle, and once it fractures it becomes extremely permeable. (Ironically, the fastest flowing aquifers are usually through "impermeable" rock.) Hence it can be hard to find suitable sites for CAES because even depleted reservoirs can become unsuitable. The previous extraction of oil/gas/water/etc can cause the a change in pressure on the capstone, causing it to slump and fracture. (Same thing can happen from cycling the CAES-system itself too deeply or too often. Similarly why underground natural gas storage has a low cycling rate, down to a once or twice per year in depleted reservoirs. And operators generally try to keep the average pressure over a year or a few years at no more than the natural pressure of the original reservoir.)

For an excavated habitat on Mars, the whole point is to dig directly into that hard self-supporting layer of rock, right? Hence you are directly altering the very rock you need to seal.

[It's a good example though. Robotbeat isn't even trying to justify his statement.]

Re: Salt deposits.

Mainly salt domes. Salt domes are awesome.

Salt layers are a poor choice though, they are apparently prone to failure once you create a cavern. Salt domes require geological uplift of a salt layer, to create a saddle structure in overlaying sedimentary rock. I'm not sure that Mars has the right geological history for such formations. But even if they exist, you're extremely restricted in sites - and it's going to be hard to find them.

So we're back to the lava-tube problem, you are unlikely to find a suitable naturally occurring habitat site that is also near a suitable ISRU source. (Unless you can find that handy liquid water aquifer.)

Remember the whole reason for suggesting mined/tunnelled habitats was that it is supposed to free you from such site restrictions.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 05:18 pm
Either the soil is porous

Well, yes.

Either way, I will expect some insulating foam to go on top (ceiling and walls), and some more complex flooring treatment for insulation, sealing, abrasion resistance.

I was talking about a working mine. Robotbeat and others suggest that the work site will be under pressure.

I'm not saying you can't seal an excavated cavity afterwards. In fact I'm saying you have to. But you can't continue to dig from within that sealed space. Hence you can't seal a working mine.

(Unless you find a nice liquid water (hypersaline?) aquifer that creates a counter-pressure against the air-pressure.)

This is assuming you'd get any leakage at all. You realize air is not going to be whooshing into the rock face, right?

It's hard to find a comparison for Earthly mining, precisely because mines/caissons are only ever pressurised to balance water pressure, never to over-pressurise. So outward flow numbers are hard to find. Instead, using inwards flow of water as a proxy, at just one atmosphere of head-pressure from a surrounding water-table and typical wet-porosity of mine-altered hard rock (~0.15ft/d), a simple 200-foot wide rock pit 20-foot below the water table can experience tens of tons of water inflow per day.

Re: CAES/etc.

These require existing, naturally occurring capped sites. (And as I said before (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1624372#msg1624372), such naturally pressurised sites are the only examples I can find for "pressurisable".)

Usually deep underground, porous (uhh, hello!) rock under some kind of capstone layer. The porous layer is usually part of a saddle structure, reducing horizontal flow away from the storage site. Note that the rock that you are storing in is not the part that's sealed, it's the over-layer that's sealed. (Typically there'll be another aquifer above the impermeable layer, providing additional hydrostatic pressure. The aquifer also helps to "capillary seal" the capstone; it's harder for gas to flow through wet rock, since it has to displace the water from each porous capillary. Slows the leak rate.)

Hence it's important that you cause as little damage to the over-layer as possible. Non-porous rock tends to be brittle, and once it fractures it becomes extremely permeable. (Ironically, the fastest flowing aquifers are usually through "impermeable" rock.) Hence it can be hard to find suitable sites for CAES because even depleted reservoirs can become unsuitable. The previous extraction of oil/gas/water/etc can cause the a change in pressure on the capstone, causing it to slump and fracture. (Same thing can happen from cycling the CAES-system itself too deeply or too often. Similarly why underground natural gas storage has a low cycling rate, down to a once or twice per year in depleted reservoirs. And operators generally try to keep the average pressure over a year or a few years at no more than the natural pressure of the original reservoir.)

For an excavated habitat on Mars, the whole point is to dig directly into that hard self-supporting layer of rock, right? Hence you are directly altering the very rock you need to seal.

[It's a good example though. Robotbeat isn't even trying to justify his statement.]

Re: Salt deposits.

Mainly salt domes. Salt domes are awesome.

Salt layers are a poor choice though, they are apparently prone to failure once you create a cavern. Salt domes require geological uplift of a salt layer, to create a saddle structure in overlaying sedimentary rock. I'm not sure that Mars has the right geological history for such formations. But even if they exist, you're extremely restricted in sites - and it's going to be hard to find them.

So we're back to the lava-tube problem, you are unlikely to find a suitable naturally occurring habitat site that is also near a suitable ISRU source. (Unless you can find that handy liquid water aquifer.)

Remember the whole reason for suggesting mined/tunnelled habitats was that it is supposed to free you from such site restrictions.

A treated cavern that is sealed already, and only the live excavation site being a potential leak site - that seems manageable.

Soil is not automatically porous, and leak rates are a function of depth (or distance to surface)

Maybe an unsealed area will cause a measurable pressure drop over a year's time, but as long as you're sealing the surfaces you're done with, it should be possible to maintain pressure while enlarging the room.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 05:33 pm
My unstated assumption is that in areas where leak rates are high, working area would be pressurized with outside air or maybe a nitrogen/argon mix. Still way better than vacuum. Makes machine design way easier. Workers only need a face mask and are otherwise basically encumbered.

Need not be full sea level pressure. 2-3 psi is sufficient. Reduces leak rate and also reduces the energy needed to replace a given mass of lost pressuring. But you can go higher if you like.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 05:38 pm
Working mines in the 1800s used air pressure to allow mining river beds. The mine was indeed active and under positive pressure. So there were are leaks, but fairly easily replaced by outside air. That's what I'm imagining here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 05:44 pm
Soil is not automatically porous,

Maybe dense clay, but ordinary regolith certainly is.

(Well, permeable. If we persist with this topic, we should both probably start trying to use "porous" and "permeable" correctly. Bubblewrap is porous but impermeable, a sieve is permeable but non-porous.)

A treated cavern that is sealed already, and only the live excavation site being a potential leak site - that seems manageable.

If we're talking about a road-header excavating outwards in a room'n'pillar type excavation, then no. If we're talking about an actual TBM with a potentially sealable cutting face "room", where you case the tunnel directly behind the TBM, maybe.

There are TBM uses that require injecting pressurised working fluid ahead of the TBM. The fluid pressure tends to fluctuate wildly, which has to be actively managed, but it shows that you can maintain a pressure difference between the head of a TBM and the rest of the tunnel. Hence it may be possible to do the opposite.

But not in a cavern. Not in a working mine. As you excavate, you are changing the mass/pressure loading on the rock. It's why you hear creaks, groans and pops inside mines, as the rock shifts behind the walls.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 05:50 pm
Soil is not automatically porous,

Maybe dense clay, but ordinary regolith certainly is.

(Well, permeable. If we persist with this topic, we should both probably start trying to use "porous" and "permeable" correctly. Bubblewrap is porous but impermeable, a sieve is permeable but non-porous.)

A treated cavern that is sealed already, and only the live excavation site being a potential leak site - that seems manageable.

If we're talking about a road-header excavating outwards in a room'n'pillar type excavation, then no. If we're talking about an actual TBM with a potentially sealable cutting face "room", where you case the tunnel directly behind the TBM, maybe.

There are TBM uses that require injecting pressurised working fluid ahead of the TBM. The fluid pressure tends to fluctuate wildly, which has to be actively managed, but it shows that you can maintain a pressure difference between the head of a TBM and the rest of the tunnel. Hence it may be possible to do the opposite.

But not in a cavern. Not in a working mine. As you excavate, you are changing the mass/pressure loading on the rock. It's why you hear creaks, groans and pops inside mines, as the rock shifts behind the walls.
Permeable, yes, better.

Why not treat the walls around the road header work site?

If air is trying to escape, it will pull your sealant in. This is a matter of rates, not of absolute air tightness.

You'll be 10s of meters underground, I just don't see massive airflow happening through that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 06:14 pm
Working mines in the 1800s used air pressure to allow mining river beds. The mine was indeed active and under positive pressure. So there were are leaks, but fairly easily replaced by outside air. That's what I'm imagining here.

You're thinking of a "pneumatic caisson". I realised that, I covered it earlier. The internal pressure is only enough to balance the water pressure. It is not a net positive pressure inside the caisson. The water provides a hydraulic seal, the sediment and rock is both gas and water permeable. There's no analogue site on Mars (unless you find a liquid aquifer) hence you can't pressurise a mine on Mars.

The external pressure on Mars is nearly zero, hence that's the default for your mine. If you want to go above that, you are extremely limited in geological structures capable of withstanding the over-pressure without leaking, especially when you are constantly shifting (by the excavation itself) the stresses on the surrounding rock.

That limit makes it extremely difficult, time consuming and expensive (in labour/resources) to even find a suitable site. It also pretty much eliminates any chance you have of finding a suitable habitat site near a suitable ISRU site. It also probably eliminates any chance that an ISRU-water mine is also a suitable site for pressurisation, which means if you need to dig for your water, you are going to be designing equipment for vacuum mining anyway.

(It's not even enough to find the right kind of rock, you have to know that the prior fracture rate is sufficiently low before you start major works. That's why depleted reservoirs are preferred for gas storage, they are already deeply studied sites with dozens to hundreds of drill sites and decades of research. And even then, it takes extensive surveying (such as test pressurisation) and millions of dollars to reach the point where you actually start pumping natural gas back down the hole.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 06:55 pm
Working mines in the 1800s used air pressure to allow mining river beds. The mine was indeed active and under positive pressure. So there were are leaks, but fairly easily replaced by outside air. That's what I'm imagining here.

You're thinking of a "pneumatic caisson". I realised that, I covered it earlier. The internal pressure is only enough to balance the water pressure. It is not a net positive pressure inside the caisson. The water provides a hydraulic seal, the sediment and rock is both gas and water permeable. There's no analogue site on Mars (unless you find a liquid aquifer) hence you can't pressurise a mine on Mars.

The external pressure on Mars is nearly zero, hence that's the default for your mine. If you want to go above that, you are extremely limited in geological structures capable of withstanding the over-pressure without leaking, especially when you are constantly shifting (by the excavation itself) the stresses on the surrounding rock.

That limit makes it extremely difficult, time consuming and expensive (in labour/resources) to even find a suitable site. It also pretty much eliminates any chance you have of finding a suitable habitat site near a suitable ISRU site. It also probably eliminates any chance that an ISRU-water mine is also a suitable site for pressurisation, which means if you need to dig for your water, you are going to be designing equipment for vacuum mining anyway.

(It's not even enough to find the right kind of rock, you have to know that the prior fracture rate is sufficiently low before you start major works. That's why depleted reservoirs are preferred for gas storage, they are already deeply studied sites with dozens to hundreds of drill sites and decades of research. And even then, it takes extensive surveying (such as test pressurisation) and millions of dollars to reach the point where you actually start pumping natural gas back down the hole.)

I'm not following.  I wasn't talking about any Earth analogs.

I'm talking about an underground room and pillar on Mars.  I'm assuming dry ground right now.

I want the room pressurized, and IIUC, you're saying there's enough flow out of the room and onto the surface of Mars so that pressurization is not practical.

I'm a bit skeptical that you can get that much flow through meters of soil, especially since when you're > 10 m below, it's not going to be loosely packed regolith.  We're assuming it has enough integrity to support room and pillar, right?

We're in agreement that the walls can be sealed after the room is complete.

So the only question is how to seal them well enough while mining is in progress, and this depends on the leak rate around the actual mining location.

My guess is that as long as there is appreciable leakage of air into the rock, any liquid you spray on the rock will get sucked into it.  This liquid can be something expensive like an epoxy, or maybe something cheap like a brine solution that solidifies once the water sublimates.  I'm sure there are experts on that.

----

Now let's do this again assuming there's a water layer above the mine.  Wouldn't said water be frozen?

--

Now let's do this again assuming there's a liquid aquifer and you're mining into it.  I'd say, move to a different location, and use this first mine as a water collector....


Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 07:08 pm
I simply don't see a problem with air leaking. It can be replaced with blowers/compressors. Like we do on Earth for any pressure-stabilized structure. Leaks are fine for any actively mined tunnel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 07:14 pm
Working mines in the 1800s used air pressure to allow mining river beds.
You're thinking of a "pneumatic caisson". I realised that, I covered it earlier. The internal pressure is only enough to balance the water pressure.
I'm not following.  I wasn't talking about any Earth analogs.

The comment you replied to was replying to Robotbeat.



Why not treat the walls around the road header work site?

For a room'n'pillar cavern, the answer is "because that's where the road-header is digging". A road header is an open cutter, you can't really seal behind it if you're trying to dig out a large horizontal cavern.

For something more like a tunnel, where only a small area is continually worked, then you can (and must) case the tunnel behind the cut. But with a road-header, you still risk a blow-out with every foot. You will not want your astronauts standing around wearing only overalls and an oxygen-mask, as RobotBeat suggests. A proper TBM might be able to seal the cutting head from the cased tunnel, but we've all agreed that true TBMs are not suitable for the job, even if we're only digging tunnels.

You'll be 10s of meters underground, I just don't see massive airflow happening through that.

Speaking in my last post of caissons... My favourite type of caisson is affectionately known as a "suction bucket". You lower a ballasted air-filled cylinder down to the sea-bed, open at the bottom and sealed at the top (like an inverted bucket). Once it has pushed through the loose sediment with its ballast-weight and reached the compacted sediment, you start pumping the air (and eventually water) out of the inside of the caisson. The partial vacuum (just a few psi difference) is enough to draw the water through the compacted sediment under and around the caisson so quickly that the sediment turns to quicksand. The caisson then rapidly sinks under its own weight into the quicksand. This works even through tens of metres of compacted sediment.

Once the caisson sinks into the sediment up to its full length, so the sediment inside the caisson reaches the inner-top, you turn off the vacuum pumps. Without the water-flow, the sediment reverts to its prior density and sets like concrete, locking the caisson down.

It's one of those "obvious in hindsight" clever ideas.

But do you see the relevance?



It also probably eliminates any chance that an ISRU-water mine is also a suitable site for pressurisation, which means if you need to dig for your water, you are going to be designing equipment for vacuum mining anyway.

I should add, if the site has water-ice, then that rock/regolith is, by definition, both porous and permeable. Otherwise how did the water get there. The ice will help reduce the permeability, but it's still prone to fracturing as you excavate. I strongly doubt you can maintain a decent atmosphere unless you go really deep before you start excavating horizontally.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 07:16 pm
We've just burned a couple of pages with this.

It's obvious that I'm not going to convince you, and you aren't going to convince me, so you guys want to jump in and have a last word, then we let this subject die?
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 07:29 pm
We've just burned a couple of pages with this.

It's obvious that I'm not going to convince you, and you aren't going to convince me, so you guys want to jump in and have a last word, then we let this subject die?
Because unlike other arguments around here, this one is actually constructive, I'm learning from it, and not in it to "Win" but at most to convince, and at least to change my mind.

So.

A roadheader  is working in a room.

Clearly it is not a tunnel, but let's assume there is a front wall that's being mined, a back wall that's all done, and two parallel walls, plus floor and ceiling, that are "growing".

Let's talk about two types of seals. A permanent one, which can even be said rock melting process, or what have you, and a temporary one (salt solution)

Maybe the temporary one is good as permanent too, if so, even better, since it is made from local ingredients.

The back and the growing walls can be sealed of course using the permanent process.

The forward wall keeps getting re-scraped, so requires the temporary sealant.

The road header is working on a section that is, what - 12' high by 12' wide?

Is it normal to wet the rock that is being excavated?  I'm thinking that sprayers can be incorporated into the arm that holds the rotating heads.

This will create a sealed layer that is continuously replenished, leaving only a few feet fo leakage.

From there, as RB says, replenish. Either with just a CO2 pressurant, or full atmosphere, depending on the rates.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/30/2016 07:32 pm
Or possibly nitrogen/argon, which is cheaper than O2 but more inert than CO2 (in case that's a problem for some reason).
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 08:24 pm
Googling "permeability of soil to air"  (no quotes) returns a bunch of readable papers.

Need to differentiate top-soil result from deeper rock, but those are starting points...

There's a paragraph somewhere that the permeability is due to cracks, not "homogeneous" porosivity - which makes intuitive sense.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 09:29 pm
Googling "permeability of soil to air"  (no quotes) returns a bunch of readable papers.

Regolith is not soil.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 09:57 pm
Googling "permeability of soil to air"  (no quotes) returns a bunch of readable papers.

Regolith is not soil.

I know it isn't.

Regolith, best that I know, is the undisturbed loose top-layer on bodies such as the moon.

Soil, again only to the best of my knowledge, is biologically active dirt, on the top layer of worlds like Earth.  (Said layer can be quite thick of course)

---

On Mars, when you're >10m deep, there's been active geology, mineralogy, and maybe biology.  It is not longer loose regolith.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/30/2016 10:12 pm
Regolith is not soil.
Regolith, best that I know, is the undisturbed loose top-layer on bodies such as the moon.
On Mars, when you're >10m deep, there's been active geology, mineralogy, and maybe biology.  It is not longer loose regolith.

I should have been more specific. Soil is a form of regolith. Regolith is the "super-group" term for everything that isn't unweathered rock. Soil is one very particular sub-category. So yes, even "when you're >10m deep" on Mars, or on Earth, it's all still regolith.

But a search for research on "soil" specifies the one material you won't find on Mars.

[Edit: So I immediately stumble over something that makes this "true, but not right", pedantically. Apparently planetologists have gotten into the habit of using "soil" to refer to regolith between around 50um and 1cm, even though it (obviously) lacks any biological material or alternation. (With "dust" for finer regolith. Not sure what they call the larger regolith? Gravel? Aggregate? Or just "loose rocks".) Still, a search for "soil research" isn't likely to bring up planetology in the first few hundred pages of results.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/30/2016 10:36 pm
So nomenclature aside, once you've bored deep enough into a hill side, I don't expect to see loose "dirt" there, but consolidated rock, and that's why RB and myself don't expect to see an uncontrollable lose of air pressure through many meters of the stuff.

Given that sealing of underground rockface is possible, I still haven't heard an argument why pressurized room-and-pillar operation is impossible.



Title: Re: Envisioning Amazing Martian Habitats
Post by: llanitedave on 12/30/2016 10:47 pm
There can be two ways that air could leak through meters of soil.  Either the soil is porous, or there are cracks/fissures in it.

You can deal with porosity with a sealant. It'll wick in a little bit, solidify, done.

Larger cracks need individual attention, like applying a filler, but I can't see this being a problem either.

This is assuming you'd get any leakage at all. You realize air is not going to be whooshing into the rock face, right?

Either way, I will expect some insulating foam to go on top (ceiling and walls), and some more complex flooring treatment for insulation, sealing, abrasion resistance.

It depends on the rock type, and its history.  Again, you need some on-site investigations before you do your design.  A long history of impacts will tend to shatter the rock in the vicinity of the impact point, the harder the rock the greater the fracturing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/31/2016 01:44 am
The notion of pressuring a tunnel doesn't much matter imho.  As has been stated up thread, you would have to apply some sort of a sealant to the surface.  In doing so, you have blocked the surfaces from constant visual inspection which is important for any tunnel or mine.  Now add heat from any operation or living conditions that will in some way affect the surrounding rock,(insulation will slow heat transfer, not stop it).  Whether the effect is to sublimate CO2 or melt any locked water in the rock, I really doubt that it will act in an anticipated way. It will certainly affect the integrity of the tunnel though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/31/2016 02:31 am
The configuration of the underground habitat is important. I envision a straight tunnel going into a hillside which is probably kept unpressurized while it is being lengthened into the hill. However, as the tunnel progresses side rooms will be added continously, and those can be lined and permanently pressurized to provide living and work space in a shirt-sleeve environment. They can be interconnected with small cross-tunnels as needed.

As for the lining it must be local conditions that influence what is needed. I imagine sintering and vitrifying from the excavation phase will be a first exterior layer. After that it could be as easy as plastering, or perhaps a multi-layer seal will be necessary. Maybe blowing up an alu-foil ballon in the rooms will provide an air-tight layer pressed against the rock face. The important thing is to find a light-weight and preferably ISRU solution.

When the main tunnel reaches its desired length and the required number of side rooms have been established I imagine that the main tunnel will be sealed off. Voilá, a first city on Mars is created. Not pretty, not romantic, but utterly practical and functional. And the digging equipment and airlocks can be re-used in its twin city nearby.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/31/2016 03:20 am
There can be two ways that air could leak through meters of soil.  Either the soil is porous, or there are cracks/fissures in it.

You can deal with porosity with a sealant. It'll wick in a little bit, solidify, done.

Larger cracks need individual attention, like applying a filler, but I can't see this being a problem either.

This is assuming you'd get any leakage at all. You realize air is not going to be whooshing into the rock face, right?

Either way, I will expect some insulating foam to go on top (ceiling and walls), and some more complex flooring treatment for insulation, sealing, abrasion resistance.

It depends on the rock type, and its history.  Again, you need some on-site investigations before you do your design.  A long history of impacts will tend to shatter the rock in the vicinity of the impact point, the harder the rock the greater the fracturing.
Agreed, but you can choose your site based on those requirements, and you have an entire planet to choose from.

With the exception of really large impactors, I don't expect the effect of meteorites hits to reach too deep underground.

Insulation will be necessary, and it actually does reduce heat impact, not just slow it - you're looking for the steady-state equilibrium condition, and the more insulation, the less impact on volatiles in the rock.

But yes - this is a matter for geologists and civil engineers, and I am neither...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/31/2016 03:15 pm
The configuration of the underground habitat is important. I envision a straight tunnel going into a hillside which is probably kept unpressurized while it is being lengthened into the hill. However, as the tunnel progresses side rooms will be added continously, and those can be lined and permanently pressurized to provide living and work space in a shirt-sleeve environment. They can be interconnected with small cross-tunnels as needed.

A straight tunnel seems like a waste, IMO. A spiral seems more efficient. You can seal and pressurise as you go, while still digging ahead.

[sealing] The important thing is to find a light-weight and preferably ISRU solution.

ISRU, yes. But why lightweight?

IMO, the key for ISRU is simplicity. It needs to use as few other resources as possible (including labour), even if it's a hideously inefficient use of material by Earth standards. Anywhere you can substitute bulk mass over manufacturing is a win.

When the main tunnel reaches its desired length and the required number of side rooms have been established I imagine that the main tunnel will be sealed off.

So your main excavated space, the entire length of the tunnel itself, is unpressurised and unusable until completed? And once completed, is a once-and-done construction, with no further expansion?

Communities, colonies, and cities don't develop like that.



Reading up on mining, tunnelling and gas storage for the previous few pages, I'm deeply skeptical that this is in any way a likely outcome for Mars. It's just such a demanding method of construction. (And the sheer effort put in to just finding a suitable site... You may have an entire planet to choose from, but you also have an entire planet to survey, pre-drill, test cut, etc.)

The only possible way it would happen is if mining is the most efficient way to dig out water-ice rich regolith, which leaves large horizontal spaces (a la room'n'pillar). So you end up with something like Coober Pedy.

(And frankly even then, open-cut seems more likely than room'n'pillar or tunnelling.)

The demands of ISRU fuel production seems like it would dominate every other aspect of colony planning. Unless your proposed colony is built around fuel production (siting, layout, access, activity), I doubt it could be seen as at all realistic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 12/31/2016 03:29 pm
I think there are advantages, even a necessity to have compartmented pressurized spaces, aka rooms that are sealed or sealable so that if a particular space gets a fracture and vents atmosphere, the residents can move into other spaces while it is being repaired, hopefully without loss of life.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/31/2016 05:46 pm
The configuration of the underground habitat is important. I envision a straight tunnel going into a hillside which is probably kept unpressurized while it is being lengthened into the hill. However, as the tunnel progresses side rooms will be added continously, and those can be lined and permanently pressurized to provide living and work space in a shirt-sleeve environment. They can be interconnected with small cross-tunnels as needed.

A straight tunnel seems like a waste, IMO. A spiral seems more efficient. You can seal and pressurise as you go, while still digging ahead.

[sealing] The important thing is to find a light-weight and preferably ISRU solution.

ISRU, yes. But why lightweight?

IMO, the key for ISRU is simplicity. It needs to use as few other resources as possible (including labour), even if it's a hideously inefficient use of material by Earth standards. Anywhere you can substitute bulk mass over manufacturing is a win.

When the main tunnel reaches its desired length and the required number of side rooms have been established I imagine that the main tunnel will be sealed off.

So your main excavated space, the entire length of the tunnel itself, is unpressurised and unusable until completed? And once completed, is a once-and-done construction, with no further expansion?

Communities, colonies, and cities don't develop like that.



Reading up on mining, tunnelling and gas storage for the previous few pages, I'm deeply skeptical that this is in any way a likely outcome for Mars. It's just such a demanding method of construction. (And the sheer effort put in to just finding a suitable site... You may have an entire planet to choose from, but you also have an entire planet to survey, pre-drill, test cut, etc.)

The only possible way it would happen is if mining is the most efficient way to dig out water-ice rich regolith, which leaves large horizontal spaces (a la room'n'pillar). So you end up with something like Coober Pedy.

(And frankly even then, open-cut seems more likely than room'n'pillar or tunnelling.)

The demands of ISRU fuel production seems like it would dominate every other aspect of colony planning. Unless your proposed colony is built around fuel production (siting, layout, access, activity), I doubt it could be seen as at all realistic.
You say "seems to" a lot, and some of it may be true, but it'd be nice to justify those opinions.

Especially since the opinions following "seems to" are the same ones you came in with...

Title: Re: Envisioning Amazing Martian Habitats
Post by: zodiacchris on 12/31/2016 10:32 pm
Okay, the last few pages were a wee bit painful to read, so here are my two cents worth as a geologist with 30 years experience in exploration, mining and engineering:

Pressurising an unlined cavern in competent rock, not loose regolith, is unlikely to be a problem on Mars. There will be a slow seep of air out if the rock is porous, but that is kept in check by capillary resistance in the interstitial spaces, provided the tunnel is deep enough. Larger fissures and faults would need to be sprayed with some expanding foam. So have some excess capability of the compressor equipment and some foam ready, and tunnel away...

And of course make the tunnel wide enough so two trucks can pass each other, and they don't have to back out in a convoy ::)

Happy New Year and good luck to you all, it is already 2017 here in Australia!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/31/2016 11:30 pm
You say "seems to" a lot, and some of it may be true, but it'd be nice to justify those opinions.
Especially since the opinions following "seems to" are the same ones you came in with...

These are the only sentences with the word "seems" in them:

A straight tunnel seems like a waste, IMO. A spiral seems more efficient. You can seal and pressurise as you go, while still digging ahead.

(And frankly even then, open-cut seems more likely than room'n'pillar or tunnelling.)

Which of the two do you feel I didn't explain my reasoning?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/01/2017 12:53 am
Pressurising an unlined cavern in competent rock, not loose regolith, is unlikely to be a problem on Mars. There will be a slow seep of air out if the rock is porous, but that is kept in check by capillary resistance in the interstitial spaces, provided the tunnel is deep enough.

Would that still apply with the pores themselves starting at near vacuum?

Ie, wouldn't the issue be the "holding capacity" of the immediate surrounding rock, before there's enough gas in the pores to create a back-pressure?

provided the tunnel is deep enough.

What kind of depth are you talking about?

not loose regolith

Is there a depth where dry regolith, compacted by the mass above, would be sufficiently impermeable?

(Especially since there should be an abundance of fines in the regolith, which AIUI reduces permeability.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/01/2017 03:43 am
You say "seems to" a lot, and some of it may be true, but it'd be nice to justify those opinions.
Especially since the opinions following "seems to" are the same ones you came in with...

These are the only sentences with the word "seems" in them:

A straight tunnel seems like a waste, IMO. A spiral seems more efficient. You can seal and pressurise as you go, while still digging ahead.

(And frankly even then, open-cut seems more likely than room'n'pillar or tunnelling.)

Which of the two do you feel I didn't explain my reasoning?

Your choice... I'm saying that "seems" implies some evidence was indicating it, and I didn't see any...

Back to tunneling and digging.

If you want to go with dig and cover, you still have a floor and two parallel walls that are the same as in mining, and you're limited to a narrow span, since you need to rebuild the roof.  You're also limited to being right underneath the surface, which makes all the "though the rock" seepage that you worry about much worse.

If you tunnel into the side of a hill, you will quickly be very deep underground, and the deeper you are, the further you are from all the surface-side issues you mentioned - loose regolith, impact-induced cracks, etc.  I mean - find a hill that's 300' tall, tunnel in until you are comfortably away from the surface (both in terms of feet and in terms of ground layers) and then expand your room and pillars.

----

In terms of ISRU, the #1 material in terms of mass will be water.  I am not sure what the best strategy for that is. Are there liquid aquifers you can tap into?  That would be extremely good news.

Subsurface ice?  Depends how deep it is...  You either excavate it (in vacuum), mine for it, or maybe try to liquefy it using direct solar insolation...  many ideas come to mind, and reality will be the judge.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/01/2017 08:30 am
If I am not mistaken, loose surface regolith, almost everywhere between latitudes 0 - 50N on Mars, has a water content of 1% to 3%. So siting is not necessarily limited by "following the ice", provided the outpost is energy-rich (i.e. nuclear power)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dalhousie on 01/01/2017 08:53 am
If I am not mistaken, loose surface regolith, almost everywhere between latitudes 0 - 50N on Mars, has a water content of 1% to 3%. So siting is not necessarily limited by "following the ice", provided the outpost is energy-rich (i.e. nuclear power)

That's in the top metre.  Deeper parts of the regolith may well contain more.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/01/2017 09:13 am
A question for the experts in here:

What would be better: tunnelling in an unsealed space, with the added complexity of having operators wearing pressure suits? - Or sealing off the tunnel as soon as it is feasible, with the added complexity of having to bring detritus out through an airlock and not having a vacuum to "clean" the air?

I am guessing that there would be an unequivocal answer, but I personally don't know which it is.
Title: Re: Envisioning Amazing Martian Habitats
Post by: AncientU on 01/01/2017 11:14 am
Mining Droids remove the complexity... cannot imagine attempting to keep a raw excavation pressurized with breathable air, so any human involvement will be in pressure suits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/01/2017 01:26 pm
Your choice... I'm saying that "seems" implies some evidence was indicating it, and I didn't see any...

I think you're reading too much into a word.

If you want to go with dig and cover, [...] you're limited to a narrow span [...]

I'm not seeing the reasoning here. Open-cut mines aren't usually narrow trenches. Someone else mentioned cut'n'cover as an alternative to habitat tunnelling, but I was talking about open-cut mining.

(http://envlaw.com.au/wp-content/uploads/mangoola_mine3.jpg) (http://=http://envlaw.com.au/wp-content/uploads/mangoola_mine3.jpg)

You're also limited to being right underneath the surface, which makes all the "though the rock" seepage that you worry about much worse.

I've never suggested you would have bare walls. I'm the one arguing against that, remember?

In terms of ISRU, the #1 material in terms of mass will be water.

It will, IMO, define the colony.

Are there liquid aquifers you can tap into? That would be extremely good news.

Everything gets a lot easier if you can just dig a well.

A fairly pure glacier would be nice too. In that case, as KelvinZero likes to suggest, you might build your habitat under "ground". The waste heat from the habitats helps pre-heat the ice from -50℃, closer to 0℃, reducing the energy needed to melt it while simplifying waste-heat management. (I think you would still "mine" the ice, rather than melt it in-situ and collect the water, because it's more controllable.)

Subsurface ice?  Depends how deep it is...  You either excavate it (in vacuum), mine for it, or maybe try to liquefy it using direct solar insolation... 

My assumption is that in the early decades, you won't have enough understanding of sub-surface geology of enough sites to find the perfect site. Hence for those first decades, you are going limited to sites you identify from orbit, slowly informed by growing surface and subsurface research. That pretty much rules out deep sites and liquid aquifers (because how would you find them?) It might also rule out easily reached glaciers (unless we get very lucky.)

Hence outside of high-latitude sites, even a "water rich" area will essentially be frozen mud. Hopefully you can find sites with >80% water content, but still just frozen mud. So I think you will need to transport the regolith to the water-extraction facility (presumably heaters. Microwaves?) As opposed to in-situ heating. That's because of the sheer quantity of water you need.

(On the flip side, you're also going to be severely limited in equipment and processing capacity. So you will want a site that has the highest water content you can find in order to minimise the amount of material you have to excavate per tonne of produced water. I don't think 1-3% water content is even remotely enough.)

I believe that resource production will be the dominant activity of a colony for its first few decades. One of the biggest resources required is fuel. That requires water. So water extraction will be the primary site-choice consideration, and the main external activity of the colony. (The main internal activity will be food production and ECLSS construction in new habs.) If open-cut mining is cheaper/easier than underground mining, which is my impression from Earth mining, then that will be the biggest activity around the colony, and the primary equipment available. Which means the best habitat is the one that takes advantage of that activity and equipment.

Which means your best habitats will be pressure-tight containers capable of being constructed from the waste-regolith coming from the water processing plant, sited in the open-cut mine and probably buried under more waste-regolith.

And for decades, that growing web of buried containers is your developing Martian city.

It may not be "amazing", but it seems fairly inevitable to me.



Mining Droids remove the complexity...

But add complexity of their own.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/01/2017 01:27 pm
Mining Droids remove the complexity... cannot imagine attempting to keep a raw excavation pressurized with breathable air, so any human involvement will be in pressure suits.

In a pressurized space fortunately there would be no need for pressure suits. If that atmosphere is pressurized martian atmosphere only, they would likely need hazmat suits. If it is a nitrogen/argon mix an oxygen mask would be enough.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 01/01/2017 01:35 pm
Don't forget mining with hot water.
Just drill a hole and pump down hot water and then water flows back up.
Its used on earth to mine sulfur.

https://en.wikipedia.org/wiki/Frasch_process
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 01/01/2017 01:40 pm
Mining Droids remove the complexity... cannot imagine attempting to keep a raw excavation pressurized with breathable air, so any human involvement will be in pressure suits.

In a pressurized space fortunately there would be no need for pressure suits. If that atmosphere is pressurized martian atmosphere only, they would likely need hazmat suits. If it is a nitrogen/argon mix an oxygen mask would be enough.

Somehow they have to remove a lot of material to the outside, so there must be an opening to Mars atmosphere while they are removing it. At some point there could be a huge airlock, but I think the best assumption is that the major tunnelling operations are done unpressurized.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/01/2017 01:46 pm
Don't forget mining with hot water.

I think that would be a good solution, when possible. Mining is all good and well but drill heads wear down quickly. They are easily replaced on earth, but they are heavy and need to be brought in from earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/01/2017 01:48 pm
Machinery in vacuum is problematic, but even 1 PSI of CO2 solves much of that.

Still though, human presence makes real-life work (e.g. maintenance and troubleshooting) much easier. This will require ~10 PSI, and preferably Oxygen.

Let's make sure we keep the discussion separate for habitat forming and ice excavation.

I'm talking about underground habitat forming, so in that context we have three options:  room and pillar, TBMs, and trench and cover.

I was arguing for R&P, which I think you can keep pressurized even while working on it.

I don't think T&C has advantages except maybe for the first small habitats. You have to work in vacuum, and sealing is more difficult because of ground proximity.

I see tunneling as suboptimal, requiring huge machinery, and producing a less than ideal product.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/01/2017 02:05 pm
Let's make sure we keep the discussion separate for habitat forming and ice excavation.

That was my point, I don't think we can. Colonies will essentially be ice mines, fuel factories, and intensive hydroponic farms for many, many decades.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/01/2017 02:12 pm
Let's make sure we keep the discussion separate for habitat forming and ice excavation.

That was my point, I don't think we can. Colonies will essentially be ice mines, fuel factories, and intensive hydroponic farms for many, many decades.
We don't know that ice will be mined, and if it is, then sure, use the mine for habitats

But if ice is collected near the surface, or through aquifers, then we're back to the question I posed, which I think also leads to mining R&P for habitats.



Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 01/01/2017 02:46 pm
All this talk about tunneling shows the complexity of the process. Instead of gigging down, how about using regolith to build up?

Make bricks by sintering regolith. Stack the bricks and sinter them together. Then cover in loose regolith for extra radiation protection. The loose covering could sintered to keep it in place. Should be easier than tunneling or mining.

The sintered bricks might leak, so an airtight coating on the interior walls would be needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/01/2017 03:32 pm
How about some cost metrics for 2017?

Just to be able to compare the various solutions and perhaps move forwards on imaginings.

I propose the following:
Energy: 1$/kWh                       
Transportation from Earth: 250$ per kg
Fabrication of Mars rated equipment on Earth: 50 000$ per tonne
Person hour of work : 100$ per hour
Robot/autonomous machine cost: 10000$/kg


How to use these:
Roadheader: 100 tonnes = 50 m$ fab. + 25 m$ trans. = 75 m$ on Mars
300 kW Working at 150 kW of power = 150$/hr
Lasting 20 years 8000 hrs per years = 75 m$/160000 = 470$ per hr
Spares and maintenance 10% = 47$
Total 667 $/hr
Ore haulers: 2 x 10T = 20T = 10M$fab + 5 m$ trans. = 15 m$ on Mars
Working at 30 kW of power = 30$/hr
Lasting 20 years 8000 hrs per years = 15 m$/160000 = 100$ per hr
Spares and maintenance 10% = 10$
Total: 140 $/hr
Semi autonomous robot helpers: 2 x 1T = 2T = 20m$ fab + 0,5m$=20.5m$
Working at 0,1 kW of power = 0,5$/hr
Lasting 20 years 8000 hrs per years = 20,5 m$/160000 = 130$ per hr
Spares and maintenance 10% = 13$
Total: 144 $/hr
Human supervision: 1000 h/y x 100 x 20 = 2m$/160000 = 12.5$/h
G-Total = 1000 $/hr (all rounded up)

If we choose rock that allows for 70m3/hr of production, then we find a cost of 15$/m3 of volume.
So a colonist that wanted 300m2 x3m high, or about 1000m3, would pay 15 000$ for the raw cave.

Leakproofing the cave:
If we suppose a volume of 15x20x3 = 810m2  and 2 kg/m2 of leak proofing.
2 x 810 = 1.6 tonnes x 250 000$/T trans= 400 000 $ +fab costs if it all comes from Earth, carbon fibre of metal, for example.
If we ship some kind of in SITU tile making machine, and reduce the leak proofing to a thin line of flexible material, at 0,1 kg per m2, then leak proofing is 20 000$
And the tiles are:
Tile maker: 20T = 10M$fab + 5 m$ trans. = 15 m$ on Mars
Working at 30 kW of power = 30$/hr
Lasting 20 years 4000 hrs per years = 15 m$/80000 = 200$ per hr
Spares and maintenance 10% = 20$
Total: 250 $/hr
If it makes 10m2 per hour, then 25$/m2
25$/m2 x 810m2 = 20 300$
G total covering = 40 300$ a reduction by a factor of 10 from all Earth materials

So the bare cost of the cave is 15000 + 40 300 = 55 000$ plus fittings such as airlocks and furniture, so it might cost just about the same as an equivalent house on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 01/01/2017 04:04 pm
Machinery in vacuum is problematic, but even 1 PSI of CO2 solves much of that.

Still though, human presence makes real-life work (e.g. maintenance and troubleshooting) much easier. This will require ~10 PSI, and preferably Oxygen.
10psi is equivalent to the high valleys of Peru (10,000ft).  Oxygen needed only if atmosphere lacks same.  Definitely need oxygen at the equivalent of the Mount Everest summit or 4.89psi
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/01/2017 05:18 pm
I don't see the gain we can get by trench digging vs tunneling.  Why should digging a trench be cheaper than tunneling?  We need to move more material in a trench, since we are moving both the final volume and the covering.  We need to build a pressure resistant vault, since the regolith cover will have no structural resistance, and this vault will be either expensive because it comes from Earth, and represents at least 25% of the final wall area, or need to be strong enough to carry the dead load of regolith without the benefit of internal pressure.
Why should digging into regolith be much cheaper than tunneling?  The soil will be compacted and require energy to break anyway.  The haulage distances will be similar.  The machinery will be similar, a heavy shovel vs a roadheader.
Anyway, as I think I show in my earlier post, the main cost of a habitat is the leak tight walls, not the volume.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/01/2017 05:23 pm
Machinery in vacuum is problematic, but even 1 PSI of CO2 solves much of that.

Still though, human presence makes real-life work (e.g. maintenance and troubleshooting) much easier. This will require ~10 PSI, and preferably Oxygen.
10psi is equivalent to the high valleys of Peru (10,000ft).  Oxygen needed only if atmosphere lacks same.  Definitely need oxygen at the equivalent of the Mount Everest summit or 4.89psi
What is the point of the air pressure again? If it is only the problem of evaporating grease and oil, might we add reservoirs and resupply regularly?
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/01/2017 05:26 pm
Machinery in vacuum is problematic, but even 1 PSI of CO2 solves much of that.

Still though, human presence makes real-life work (e.g. maintenance and troubleshooting) much easier. This will require ~10 PSI, and preferably Oxygen.
10psi is equivalent to the high valleys of Peru (10,000ft).  Oxygen needed only if atmosphere lacks same.  Definitely need oxygen at the equivalent of the Mount Everest summit or 4.89psi
What is the point of the air pressure again? If it is only the problem of evaporating grease and oil, might we add reservoirs and resupply regularly?
That, cooling, etc.  (Look at the fan at the back of a bobcat...  )

But more than that. Machines operating in a place like a mine (from excavators to conveyer belts) need constant maintenance.  I'd rather not do it in space suits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/01/2017 05:36 pm
How about some cost metrics for 2017?
[...]
then we find a cost of 15$/m3 of volume.
[...]
So the bare cost of the cave is 15000 + 40 300 = 55 000$ plus fittings such as airlocks and furniture, so it might cost just about the same as an equivalent house on Earth.

Yesterday I found a promotional piece from the Australian Tunnelling Society (http://www.ats.org.au/index.php/resources/tech-papers/planning-of-underground-structures/73-underground-space-commercial-development/file) advocating underground buildings.

For a room'n'pillar space for a hypothetical underground archive, they price the excavation at $811,200 for 7800m³. Not including project management, geo surveys, etc. Giving over $100/m³ just for the bare excavation. Total cost to turn-key is given at $1.6m (I'm excluding fittings), over $200/m³ of excavated volume, and around $615/m² of floor space.

And remember, this is an industry promotional puff-piece, intended to make the idea of underground facilities seem as viable as possible compared to conventional construction.

That suggests your numbers are likely an order of magnitude too low, even for a project on Earth at a favourable site.

On Mars, with no existing infrastructure and 2 years between shipments?

[The New Irvine pipeline (a 8.5ft by 3.5mile tunnel dug with a roadheader) cost $339m. Or nearly $12,000 per m³ of usable volume, including 3,500 tonnes of grout.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/01/2017 05:39 pm
How about maintenance using remote manipulators?

As per joined image.  Not required on Earth, but might be cheaper to develop than airtight mining.

I think we might get by with radiative cooling, or at worst with piped cooling, such as a glycol line in parallel with the power line illustrated
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/01/2017 05:41 pm
Machinery in vacuum is problematic, but even 1 PSI of CO2 solves much of that.

Still though, human presence makes real-life work (e.g. maintenance and troubleshooting) much easier. This will require ~10 PSI, and preferably Oxygen.
10psi is equivalent to the high valleys of Peru (10,000ft).  Oxygen needed only if atmosphere lacks same.  Definitely need oxygen at the equivalent of the Mount Everest summit or 4.89psi
What is the point of the air pressure again? If it is only the problem of evaporating grease and oil, might we add reservoirs and resupply regularly?
That, cooling, etc.  (Look at the fan at the back of a bobcat...  )

But more than that. Machines operating in a place like a mine (from excavators to conveyer belts) need constant maintenance.  I'd rather not do it in space suits.

Cooling is a very big one. Material compatibility is also important. And yeah, maintenance also huge. Being able to have full dexterity while fixing something helps a LOT. A face mask may be annoying, but astronaut gloves make even simple task very hard.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/01/2017 05:48 pm
How about maintenance using remote manipulators?

As per joined image.  Not required on Earth, but might be cheaper to develop than airtight mining.

I think we might get by with radiative cooling, or at worst with piped cooling, such as a glycol line in parallel with the power line illustrated
If you've ever did inspection or maintenance on heavy equipment, it requires a level of dexterity you can't get from robots. 

And who maintains the maintaining robots?  This is not a sterile lab environment...

Sealing the walls, if necessary, will be something that's part of underground life anyway...  And if you're just pressurising as discussed above, will be very easy to accomplish, since small leaks are not a problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/01/2017 05:54 pm
How about maintenance using remote manipulators?

As per joined image.  Not required on Earth, but might be cheaper to develop than airtight mining.

I think we might get by with radiative cooling, or at worst with piped cooling, such as a glycol line in parallel with the power line illustrated
If you've ever did inspection or maintenance on heavy equipment, it requires a level of dexterity you can't get from robots. 

And who maintains the maintaining robots?  This is not a sterile lab environment...

Sealing the walls, if necessary, will be something that's part of underground life anyway...  And if you're just pressurising as discussed above, will be very easy to accomplish, since small leaks are not a problem.
Not robots, remote manipulators, waldoes, if you prefer.  Brain surgery is sometimes done this way, so I expect oil changes can be done as well.  Maintenance on Mars should be done in a nice warm pressurized maintenance shacks, not on site.  Except for the roadheader and its conveyor belt.  We might wheel it out from time to time, if we are not digging too deep.  And we could create local maintenance shelters as we dig.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/01/2017 05:58 pm
BTW I have designed two maintenance garages for 100 tonnes mining trucks, Osisko gold mine and Detour gold mine.  I've also been involved with quite a few others.

Never did the maintenance myself though :-)  Don't even change the oil in my car.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/01/2017 06:07 pm
BTW I have designed two maintenance garages for 100 tonnes mining trucks, Osisko gold mine and Detour gold mine.  I've also been involved with quite a few others.

Never did the maintenance myself though :-)  Don't even change the oil in my car.
Yes, manipulators.  Still, when you have a tractor arms that's full of muck and grease, and you have to pry it loose with a crowbar, while standing on the fender which is bent because a rock got stuck under it last month - a person can do it in 5 minutes, and I don't know how a manipulator can do it at all.

Brain surgery is exactly the kind of example suitable for a manipulator better than to a human hand.  A bit like CNC machining.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 01/02/2017 05:02 am
I don't see the gain we can get by trench digging vs tunneling.  Why should digging a trench be cheaper than tunneling?  We need to move more material in a trench, since we are moving both the final volume and the covering.  We need to build a pressure resistant vault, since the regolith cover will have no structural resistance, and this vault will be either expensive because it comes from Earth, and represents at least 25% of the final wall area, or need to be strong enough to carry the dead load of regolith without the benefit of internal pressure.
Why should digging into regolith be much cheaper than tunneling?  The soil will be compacted and require energy to break anyway.  The haulage distances will be similar.  The machinery will be similar, a heavy shovel vs a roadheader.
Anyway, as I think I show in my earlier post, the main cost of a habitat is the leak tight walls, not the volume.

Mining companies prefer strip mining because it is cheaper. If the ore they want is too deep underground, they have to tunnel. Appalachian coal mines used to be tunnels into the mountains. With new mines the companies just strip the mountain top off.

Regolith is loose material. You don't tunnel into loose material unless you want to be buried alive. You tunnel into rock.

If you want structures just below the surface for radiation protection, use cut and cover.

If you want to go deep into a hill, dig a tunnel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/02/2017 11:09 am
Mining companies prefer strip mining because it is cheaper.

Cheaper because they don't put a structure over the trench and pressurize it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Torbjorn Larsson, OM on 01/02/2017 02:52 pm
Mining companies prefer strip mining because it is cheaper.

Cheaper because they don't put a structure over the trench and pressurize it.

If you want cheap, why not do a Heinlein and put a roof on another Eagle sized - r=22, d=3 m - crater? Maybe even do some of the pressure bearing thing, assuming the shield load (possibly the dig out gravel) is too heavy for an all out Bigelow roof design..
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/02/2017 03:40 pm
Mining companies prefer strip mining because it is cheaper.
Cheaper because they don't put a structure over the trench and pressurize it.

You wouldn't "put a structure over the trench", you would put a prefabbed pressure vessel inside the trench and cover it.

(The pressure vessel could be made of ISRU materials. It's supported on all sides, so it can be a compression-preferring material, expanding the choice of materials. But at first it might be Earth-supplied inflatable modules, until there's enough industry (and spare resources) to support local construction materials.)

AIUI (http://www.dr-sauer.com/files/drsauer/public/content/file/1486/upload/comparison-cut-and-cover.pdf), the reason tunnelling sometimes competes with cut'n'cover for modern projects in established cities is because of the disruption to surface roads and the cost of dealing with the web of existing utilities, most old, many undocumented. Tunnels can just go under it all. Without that hassle, cut'n'cover remains the cheapest option.

That said, as I mentioned earlier, I'm not talking about "trenches" dug specifically for the habitats, I'm talking about using open-cut areas that are created from water extraction. Simply because that's what the colony is doing, that's the equipment available, the material available and the excavated volume available.

And once you establish a method of habitat construction, IMO that method will become standard for decades; simply because it's what the builders know, it's what their methods and equipment are specialised for. (You see that in historical colonies and early cities on Earth, there tends to be a single building type that dominates each region for a long time.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/02/2017 03:44 pm
If you want cheap, why not do a Heinlein and put a roof on another Eagle sized - r=22, d=3 m - crater? Maybe even do some of the pressure bearing thing, assuming the shield load (possibly the dig out gravel) is too heavy for an all out Bigelow roof design..

At 1 atmosphere, the outward pressure is 10 tonnes of force per square metre of enclosed space. On Mars, to get 10 tonnes of force from gravity-loading, you need at least 26 tonnes of mass per square metre. Assuming 2.5 tonnes per cubic metre, that's around 10 metres depth of material merely to balance the internal pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/02/2017 05:28 pm
Why this obsession with exactly Earth pressure? Seems overkill.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/02/2017 06:27 pm
Why this obsession with exactly Earth pressure?

I wonder. Similar to those who demand artificial gravity on Mars transfer. Or those who declare radiation lethal and demand we cannot leave LEO unless we carry several meters of shielding around the habitats in flight. And those who say Mars gravity so so much lower than earth that it is unethical to even try finding out if we can live there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/02/2017 07:19 pm
Why this obsession with exactly Earth pressure?

Fire.

[Edit: 1atm was just illustrative. If you want the numbers for half an atmosphere, divide by 2. My point was that any reasonable "shielding" over a structure will not be thick enough to counter the force from atmospheric pressure. Therefore the structure won't be in compression, as implied by Torbjorn Larsson. The "shield load" will never be "too heavy" for the structure.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/02/2017 07:26 pm
It's a LOT harder to start a fire in Mexico City (11psi) than sea level (15psi).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/02/2017 07:56 pm
It's a LOT harder to start a fire in Mexico City (11psi) than sea level (15psi).

Fine, "around 7 metres depth of material merely to balance the internal pressure.". Happy now?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Nomadd on 01/02/2017 08:35 pm
If you want cheap, why not do a Heinlein and put a roof on another Eagle sized - r=22, d=3 m - crater? Maybe even do some of the pressure bearing thing, assuming the shield load (possibly the dig out gravel) is too heavy for an all out Bigelow roof design..

At 1 atmosphere, the outward pressure is 10 tonnes of force per square metre of enclosed space. On Mars, to get 10 tonnes of force from gravity-loading, you need at least 26 tonnes of mass per square metre. Assuming 2.5 tonnes per cubic metre, that's around 10 metres depth of material merely to balance the internal pressure.
That can't be right. All you need to hold pressure is plastic sheeting and duct tape. Unless you think you're smarter than Hollywood script writers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/02/2017 08:50 pm
If you want cheap, why not do a Heinlein and put a roof on another Eagle sized - r=22, d=3 m - crater? Maybe even do some of the pressure bearing thing, assuming the shield load (possibly the dig out gravel) is too heavy for an all out Bigelow roof design..

At 1 atmosphere, the outward pressure is 10 tonnes of force per square metre of enclosed space. On Mars, to get 10 tonnes of force from gravity-loading, you need at least 26 tonnes of mass per square metre. Assuming 2.5 tonnes per cubic metre, that's around 10 metres depth of material merely to balance the internal pressure.
That can't be right. All you need to hold pressure is plastic sheeting and duct tape. Unless you think you're smarter than Hollywood script writers.
Maybe they just used the wrong kind of tape? Dyneema Or Kevlar would've worked.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/02/2017 08:55 pm
That can't be right. All you need to hold pressure is plastic sheeting and duct tape. Unless you think you're smarter than Hollywood script writers.
Isn't that just about everybody?[1]

The thing about pressure used for load bearing though? If you have a blowout somewhere and can't reseal your roof is coming down. We've been round this loop before, the ideal structure can handle the regolith load and the pressure either way.

1 - to be fair, I think it is the studio executives... they overrule writers who know better in search of more "punch" to the story.
Title: Re: Envisioning Amazing Martian Habitats
Post by: zodiacchris on 01/02/2017 09:28 pm
Hmmm, plastic and ductape...

How about this (might have been covered up thread?):

Assume you have a nuclear reactor that is providing abundant waste heat and subsurface ice to produce large amounts of liquid water. Either excavate a large pit, or look for a suitable small but deep crater. Line with plastic (stands for a suitable impermeable membrane). Drill anchors into ground and install inflatable habitat, can be relatively thin skinned, preferred clear or translucent. Inflate to achieve shape, then cover the whole thing with a top membrane and weld it to the base layer, forming a large bladder. Slowly fill with water to depth of approx 20 m, while increasing the pressure inside the habitat. The surface layer should prevent evaporation, the water sufficient pressure, radiation protection and thermal buffer.
Of course you'd need entry air locks to the surface, a few hard shell sections for emergencies, but the mayority of the habitat could be basically flat packed pre-welded plastic tarp. Easy to transport, fairly straightforward to set up if a suitable hole is available (melt one into glacier?) easy maintenance of habitat sections with a moon pool and scuba gear.

Shame about the nuclear reactor though, that'd be hard to get...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/02/2017 10:04 pm
I'd rather dig a tunnel ten meters underground than have to pile ten meters of material on top of an open trench. Open trenches are great when you can leave them... open. When you are working in a near-vacuum and need to pile regolith on top to keep them structurally viable they stop making sense.

Mars already provided structurally sound housing in the form of hills. You just need to empty out the junk from them, i.e. hollow them out a bit. Fixer-upper houses for a fixer-upper planet :-)

Tunnelling is the obvious choice for the first Martian non-prefab housing which is why that was the technique mentioned by Musk in his Reddit AMA. The obvious prefab housing in the early stages of Martian colonization are the lander stages. But where do we go from there?

While living in the lander stage I imagine that a small crew can deploy a digger and get to work on a tunnel. Twenty meters straight into a hill side or a cliff face they should be able to excavate a side room. While continuing the main tunnel further into the hill they can start investigating lining techniques in the side room. At some point an airlock can be installed and after extensive air pressurization and air quality tests are completed we'll have our first on-site constructed living space on Mars. It will be momentous!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/03/2017 07:27 pm
Here is a cost spreadsheet of a roadheader dug cave, a trench dug habitat and a ice wall bubble, with inflatable bladder.

The 1000 m3 roadheader cave is 30 000$, the trench cave is 27 000 $ using Mars in situ materials and the ice bubble is 300 000$.

The main problem with the bubble is cost of the inflatable bladder, that I presume must come from Earth, and the cost of melting all that water.

The trench dug habitat wins out if the walls can be made self supporting with no air pressure and only 3-4 m of regolith on top, using cheap leakproof blocks and if the production rate is high. To be honest, trench and tunnel are pretty much the same cost, since the calculation have a huge margin of uncertainty.

Fabricated domes are  1, maybe 2 orders of magnitude more expensive than tunnels, unless there are glass and steel making machine on Mars.

A few conclusions:

-Underground volume is cheap.  It's making that volume leak proof that is expensive.
-If lavatubes are not airtight, sealing them will negate all the savings because of the cost of the walls.
-We don't need airtight rock, we need to be able to build an airtight membrane with insitu resources.  All we need is loadbearing rock.
-Melting ice is more then 10 times more energy intensive than breaking rock.  It makes no sense to melt caves on Mars, it's much more practical to dig them.
-It takes less energy to melt any type of rock than to melt ice, the phase change energy is lower.  It's just that melting rock requires high temperatures.  Equipment that recycles the heat used to heat the rock could melt rock more efficiently than ice.

-Unless someone actually reads the spreadsheet and proves me very wrong, I will persist with roadheader built caves as the main living and production areas, with rare domes as leisure/horizon opening spots.  I suppose we can start will smaller digging machines, with a 3mx3m head movement; some are as small as 20 tonnes.  We can use larger machines latter.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/03/2017 07:57 pm
I agree with all your conclusions lamontagne. Good speculative work!

Here's an article on Coober Pedy, the famous Australian Opal mining capital of the world, where most of the homes (called 'dug-outs') are made with roadheaders: http://radio-weblogs.com/0119080/stories/2003/05/30/galleryLivingDownUnder.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/03/2017 08:04 pm
If glazing using microwaves does work with the rock, making them airtight should be straightforward for most of the surface. Maybe some cracks need imported materials.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/03/2017 08:55 pm
Here is a cost spreadsheet of a roadheader dug cave, [...]
The 1000 m3 roadheader cave is 30 000$,

As I said earlier, the industry itself (http://www.ats.org.au/index.php/resources/tech-papers/planning-of-underground-structures/73-underground-space-commercial-development/file) gives figures above $100/m³ for the roadheader excavation alone, even when it's trying to promote the idea as favourably as possible. If your model fails for Earth, under favourable assumptions and with full access to urban facilities, then it is going to be horribly wrong for Mars.

(And for an actual project, such as the New Irvine pipeline (http://www.antraquip.net/files/Antraquip%20WT%20Jan-Feb%2016.pdf) (a 8.5ft by 3.5mile tunnel dug with a roadheader and sealed with grout), the project cost was $339 million. No internal structure, just a dumb tube. That's nearly $12,000 per m³ of usable volume, including project costs, such as 3,500 tonnes of grout. (About 600kg/lm or 80kg/m².))
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/03/2017 09:17 pm
Hmmm, plastic and ductape...
[...] a large pit, [...] Line with plastic (stands for a suitable impermeable membrane). Drill anchors into ground and install inflatable habitat, can be relatively thin skinned, preferred clear or translucent. Inflate to achieve shape, then cover the whole thing with a top membrane and weld it to the base layer, forming a large bladder. Slowly fill with water to depth of approx 20 m, while increasing the pressure inside the habitat. The surface layer should prevent evaporation, the water sufficient pressure, radiation protection and thermal buffer.

Do you mean the water is between the two layers, essentially trapped in a plastic pocket, which is in turn wrapped around an air-pocket? Then, yes it should work. As in the Ice Home design (http://www.space.com/35101-mars-ice-home-design.html). (In that case, they use a layer of ice, then an insulating later of CO2-filled "bubblewrap", then a layer of liquid water, then a toroidal air-filled habitat.)

However, if you mean the membranes are anchored to the floor in separate layers, with the air layer and water layer being exposed to regolith, then no. You'll need a air/water-tight foundation/walls to hold both the air and the water. And even then, while a dome works (if you have enough tensile strength or enough weight on it), domes are not a good structure to hold internal pressure. Why start with something that isn't suited to the job and then add other things to force it to fit, just because you like the image of a "dome"? You might as well start with "bubble", since that's what everything is trying to do anyway, a sphere/spheroid, capped cylinder, or torus.

[If you meant the water is on top of the pressure membranes, so the habitat is like an air-filled dome anchored to the bottom of a lake, then no. In the short term, the water will create buoyancy in the habitat that is much greater than the air-pressure you already need to contain. (It will also try to deform the structure into a bubble, so add crushing force on the sides.) Longer term, the water will boil away fairly quickly at Mars pressures (even at the deepest sites with the highest salinity, it is still so close to the boiling point that it will evaporate too quickly (think of a pot of water that's not yet boiling, but is still "steaming" like crazy)), making it a very wasteful design even if it worked.

So I'm assuming you meant water between the two layers.]




"Ice Home"

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30500000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-31_1482399958005.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30500000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-31_1482399958005.jpg)

(http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30900000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-35_1482399958123.jpg) (http://i.dailymail.co.uk/i/pix/2016/12/22/09/3B92D30900000578-4057680-Intense_space_radiation_is_a_significant_problem_for_health_on_l-a-35_1482399958123.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/03/2017 09:22 pm
This feels like a sill question. It should be obvious to me but I can't get the flow of forces clear in my head.



While replying to ZodiacChris, I came up with a variant on his suggestion: Picture of a "cup" inside a depression/crater/excavation/whatever/don'tcare, made from a water/airtight compressive material. (On Earth you might use reinforced concrete with a liner or an appropriate sealer additive.)

On top of the cup you have two well-anchored membranes between which you fill with water, like a water-mattress or water pillow. It's supported only around the rim.

If the inside of the cup is unpressurised (relative to the outside), the water pillow will hang down in a catenary. (The water will then try to pool in the middle, but I'm ignoring that.)

If the inside of the cup is over-pressurised, the water pillow will create a dome (well, an upward catenary). (The water will try to pool around the edges, but I'm ignoring that.)

But what happens if the internal pressure is juu.uust right...?

Will the water pillow form a flat layer? (As I've sketched below.) Or some other shape? (Such as a "W", where the centre bows upwards, trying to create a spherical air-bubble, while near the edges it sags due to the weight of the centre. Or an "M" where the centre sags, but closer to the edge bows up.)

If I picture a hypothetical infinite-plain case, my brain says "flat". But if I look at the "cup", my brain says "W" bubbe-sag.

[edit: restored a missed word]
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/04/2017 02:15 am
Here is a cost spreadsheet of a roadheader dug cave, [...]
The 1000 m3 roadheader cave is 30 000$,

As I said earlier, the industry itself (http://www.ats.org.au/index.php/resources/tech-papers/planning-of-underground-structures/73-underground-space-commercial-development/file) gives figures above $100/m³ for the roadheader excavation alone, even when it's trying to promote the idea as favourably as possible. If your model fails for Earth, under favourable assumptions and with full access to urban facilities, then it is going to be horribly wrong for Mars.

(And for an actual project, such as the New Irvine pipeline (http://www.antraquip.net/files/Antraquip%20WT%20Jan-Feb%2016.pdf) (a 8.5ft by 3.5mile tunnel dug with a roadheader and sealed with grout), the project cost was $339 million. No internal structure, just a dumb tube. That's nearly $12,000 per m³ of usable volume, including project costs, such as 3,500 tonnes of grout. (About 600kg/lm or 80kg/m².))
Thank you for the references.  I have upgraded the spreadsheet accordingly.  The conclusions do not change, but it's more expensive to build, and since I used 1 ft thick walls for the trench and 2 inch walls for the tunnels, it now is more expensive than the tunnel.

Interestingly, the transportation costs are not all that important in the grand scheme of things.  It's mostly personnel and equipment availability.  I don't know how automated the work planned in Australia was, but my guess is that we can use more automation in the Mars works.  So my costs are a bit lower.

As far as the long tunnel goes, my guess is that the cost to move the material out of the single long tunnel was very high, with a 5km conveyor belt, and that increased the costs.  Perhaps there's also a reason why Elon Musk has decided to go into tunneling... ;-)

So I've updated the spreadsheet.  The costs are in line with the Australian works, once I take financing, profits, insurance and production losses into account with a magic fudge factor of 2x.

I've added an estimate of the work to melt the rock into plates and blocks.  It's probably optimistic.
The cost of the glass dome is now less than an order of magnitude more expensive.  Perhaps 2 or 3x?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/04/2017 02:19 am
This feels like a sill question. It should be obvious to me but I can't get the flow of forces clear in my head.



While replying to ZodiacChris, I came up with a variant on his suggestion: Picture of a "cup" inside a depression/crater/excavation/whatever/don'tcare, made from a water/airtight compressive material. (On Earth you might use reinforced concrete with a liner or an appropriate sealer additive.)

On top of the cup you have two well-anchored membranes between which you fill with water, like a water-mattress or water pillow. It's supported only around the rim.

If the inside of the cup is unpressurised (relative to the outside), the water pillow will hang down in a catenary. (The water will then try to pool in the middle, but I'm ignoring that.)

If the inside of the cup is over-pressurised, the water pillow will create a dome (well, an upward catenary). (The water will try to pool around the edges, but I'm ignoring that.)

But what happens if the internal pressure is juu.uust right...?

Will the water pillow form a flat layer? (As I've sketched below.) Or some other shape? (Such as a "W", where the centre bows upwards, trying to create a spherical air-bubble, while near the edges it sags due to the weight of the centre. Or an "M" where the centre sags, but closer to the bow up.)

If I picture a hypothetical infinite-plain case, my brain says "flat". But if I look at the "cup", my brain says "W" bubbe-sag.
Constant vertical uniform load = constant uniform vertical force.  Flat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/04/2017 03:34 am
As far as the long tunnel goes, my guess is that the cost to move the material out of the single long tunnel was very high, with a 5km conveyor belt, and that increased the costs.

Where on Earth did you get the idea that there was a 5km conveyor belt?

[I suspect your numbers are still wildly optimistic even for a project on Earth.]

But what happens if the internal pressure is juu.uust right...?
Constant vertical uniform load = constant uniform vertical force.  Flat.

Yeah, that's what part of me "said". The other part said, "dude, no way".

If it's true, then it makes an interesting variant (perhaps even "amazing") because the vast majority of the loading from weight of the water is transferred to the floor. Straight down. The water pillow isn't being supported by the walls, but by the air pressure. Likewise, there's very little tensile loading on the membranes.

The load from air-pressure on the side walls should be purely compressive because of the nature of the siting.

A small remaining load will tend to concentrate around the top edge, because of the shape of the space, but that should be easily handled by the walls.

Disadvantages: The shape is self-shadowing, so light is an issue. But it's vastly better than completely buried designs.

You could terrace around the upper walls for crops, areas that receive the least shadowing, augmented by artificial light. The extra waste heat also helps keep the water layer liquid. It will probably still need to be highly saline, enough to rule out aquaculture. And it will probably still freeze over in winter. Perhaps the three layers from the Ice Home design? Outer membrane. Layer of highly saline water. Membrane. Insulating CO2 bubblewrap. Membrane. Fresh water. Inner membrane. Inhabited volume.

However, if there's a decent transparent membrane which can handle tension loads, another alternative is to replace the depression/excavation/crater/whatever with a series of water-containing toroids. That way the design can sit out on a flat surface. More light.

And that should be much more scalable than most designs, you can go wider without increasing the height, making it a more efficient use of space than domes or spheroids. The flat roof might also allow cities to expand in a more natural, cellular way...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/04/2017 12:04 pm
As far as the long tunnel goes, my guess is that the cost to move the material out of the single long tunnel was very high, with a 5km conveyor belt, and that increased the costs.

Where on Earth did you get the idea that there was a 5km conveyor belt?

[I suspect your numbers are still wildly optimistic even for a project on Earth.]

But what happens if the internal pressure is juu.uust right...?
Constant vertical uniform load = constant uniform vertical force.  Flat.

Yeah, that's what part of me "said". The other part said, "dude, no way".

If it's true, then it makes an interesting variant (perhaps even "amazing") because the vast majority of the loading from weight of the water is transferred to the floor. Straight down. The water pillow isn't being supported by the walls, but by the air pressure. Likewise, there's very little tensile loading on the membranes.

The load from air-pressure on the side walls should be purely compressive because of the nature of the siting.

A small remaining load will tend to concentrate around the top edge, because of the shape of the space, but that should be easily handled by the walls.

Disadvantages: The shape is self-shadowing, so light is an issue. But it's vastly better than completely buried designs.

You could terrace around the upper walls for crops, areas that receive the least shadowing, augmented by artificial light. The extra waste heat also helps keep the water layer liquid. It will probably still need to be highly saline, enough to rule out aquaculture. And it will probably still freeze over in winter. Perhaps the three layers from the Ice Home design? Outer membrane. Layer of highly saline water. Membrane. Insulating CO2 bubblewrap. Membrane. Fresh water. Inner membrane. Inhabited volume.

However, if there's a decent transparent membrane which can handle tension loads, another alternative is to replace the depression/excavation/crater/whatever with a series of water-containing toroids. That way the design can sit out on a flat surface. More light.

And that should be much more scalable than most designs, you can go wider without increasing the height, making it a more efficient use of space than domes or spheroids. The flat roof might also allow cities to expand in a more natural, cellular way...
The tunnel is about 9 feet wide (8.5ft +grout).  Trucks cannot cross, so conveyor belt.  The tunnel is 5km long.  Maybe they started at each end then there are 2x2.5 km conveyor belts.  Conveyor belts are cheaper than trucks.  How else do you remove material from the rock face?

You don't need a trench, as this is a variation on atmospheric pressure supported domes.  The main risk I see is blowout at the junction point with the soil, you might want to overlap some of the roof over the edge of the trench to add mass there.
I still think the membrane and the ice will end up being more expensive than an equivalent tunnel though.
If you put the water in cells, then you can probably fill the blanket in the trench, then slowly add pressure under it.  Eventually it will rise up and become flat. So basically, you only need a compressor to inflate this.

I hope we agree that the cost for the Irvine water tunnel pipeline includes other stuff than the tunnel itself, since it's 4600$ per tonne of extracted rock.  Market price for Aluminium is 1700 $ per tonne and steel 300$ per tonne.  And that has to be mined, melted and formed.  And bauxite and iron ore shipped half way around the world.  I expect the civil works mining machinery usually spends most of its life idle, so a contract needs to finance equipment acquisition over a short number of hours.  Mining on Mars should be a continuous activity.  Should be cheaper than the average prices on Earth the autralian study uses, with very low idle times, perhaps not the 95% use of an ore mine mill, but close.


Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/04/2017 12:36 pm
I hope we agree that the cost for the Irvine water tunnel pipeline includes other stuff than the tunnel itself, since it's 4600$ per tonne of extracted rock.  Market price for Aluminium is 1700 $ per tonne and steel 300$ per tonne.  And that has to be mined, melted and formed.  And bauxite and iron ore shipped half way around the world.

I love that argument.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 01/04/2017 01:29 pm
Do you mean the water is between the two layers, essentially trapped in a plastic pocket, which is in turn wrapped around an air-pocket? Then, yes it should work. As in the Ice Home design (http://www.space.com/35101-mars-ice-home-design.html). (In that case, they use a layer of ice, then an insulating later of CO2-filled "bubblewrap", then a layer of liquid water, then a toroidal air-filled habitat.)

Cool drawings, but I think these individual habitat ideas are non-starters for one simple reason.  Cost.

IMHO, this conversation needs to get out of the mindset of planning for Ozzie and Harriet living in their own homes on Mars like it's some exurb of Chicago.  Waaaaaaaaaaaaaaaaaaaaaaaay too expensive. 

The Occam's Razor solution dictates a minimal cost to construct for the maximum number of people because the cost of housing will be numerous orders of magnitude more expensive than anything on Earth due to shipping costs.  Think apartment buildings or worker dormitories (or ship berths) like megacity dwellers and not stand-alone housing.

The cheapest surface habitat designs (that we've covered numerous times) will be a large pressure bladder mailed from Earth and soil or blocks created on Mars to provide mechanical support.  Even that is not a scalable solution for a civilization to take root.  For example, a current Bigelow inflatable will take up so much room, you'd only get one (maybe two) per trip up there, and it'd only house a few people- with terrible radiation protection.  That's not a recipe for expansive colonization even if it works for the first outpost structures.

The next cheapest solution is to dig tunnels and line them with pressure bladders, or better yet, glassify the tunnel walls to act as pressure vessels and skip the pressure bladder shipped from Earth....
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/04/2017 09:36 pm
You don't need a trench

Where did I ever mention a trench?

as this is a variation on atmospheric pressure supported domes.

Not really. It converts the tensile forces into compression. That is more compatible with ISRU construction.

The main risk I see is blowout at the junction point with the soil

What soil?

I hope we agree that the cost for the Irvine water tunnel pipeline includes other stuff than the tunnel itself

They had to create a water-tight, pressurisable system. That was the relevance to the topic.

Market price for Aluminium is 1700 $ per tonne and steel 300$ per tonne.

These days, ore is mostly taken from giant open cut mines, which are a) cheaper than underground mines, and b) scale much better than tunnelling. So it's impossible to compare them with the much smaller scale of operation you would have for habitat construction.

Mining on Mars should be a continuous activity.  Should be cheaper than the average prices on Earth the autralian study uses

You think that an activity on another planet will be cheaper than digging a hole on Earth?



Cool drawings, but I think these individual habitat ideas

I'm not suggesting Ice House-scale dwellings. Those are intended for bases, not colonies. I'm just talking about the building method, having layers of ice/water/insulation. There's no reason it shouldn't scale up.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dalhousie on 01/04/2017 11:12 pm
Mining Droids remove the complexity... cannot imagine attempting to keep a raw excavation pressurized with breathable air, so any human involvement will be in pressure suits.

Mining droids?  Exactly how far into the future are we talking about?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/05/2017 01:05 am
You don't need a trench

Where did I ever mention a trench?
Quote
A hole, a donut, the space between the red wall in the image, looks like a trench to me
as this is a variation on atmospheric pressure supported domes.

Not really. It converts the tensile forces into compression. That is more compatible with ISRU construction.
Quote
So does a dome if it is heavy enough.  It is exactly the same as a massive dome
The main risk I see is blowout at the junction point with the soil

What soil?
Quote
the side of the trench
I hope we agree that the cost for the Irvine water tunnel pipeline includes other stuff than the tunnel itself

They had to create a water-tight, pressurisable system. That was the relevance to the topic.
Quote
Nevertheless the cost is way higher and the reference not very relevant
Market price for Aluminium is 1700 $ per tonne and steel 300$ per tonne.

These days, ore is mostly taken from giant open cut mines, which are a) cheaper than underground mines, and b) scale much better than tunnelling. So it's impossible to compare them with the much smaller scale of operation you would have for habitat construction.
Quote
My point was not to compare mining cost but to show the pipeline costs were too high

Mining on Mars should be a continuous activity.  Should be cheaper than the average prices on Earth the autralian study uses

You think that an activity on another planet will be cheaper than digging a hole on Earth?
Quote
Yes.  Why not?  There is a spreadsheet, if you look at the spreadsheet rather than reason by analogies we can see where I am wrong.  Otherwise there is no point in the discussion.



Cool drawings, but I think these individual habitat ideas

I'm not suggesting Ice House-scale dwellings. Those are intended for bases, not colonies. I'm just talking about the building method, having layers of ice/water/insulation. There's no reason it shouldn't scale up.
Sorry, haven't quite mastered the quote insertion method.
The analogies are interesting, but I would prefer discussing what is wrong with the numbers I am proposing in the spreadsheet.  Reasoning by analogy can be misleading.
As using bad numbers can be, of course ;-)

The cost of the machinery, plus transportation, plus the cost of the power, plus the cost of the man hours, plus the cost of management and such.  I just can't find the high costs you expect.

There are large economies possible with robotic equipment.  This failed about 20 years ago, when some attempts were made at automated mining.  This seems more likely today, IMHO.



Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/05/2017 01:06 am
Mining Droids remove the complexity... cannot imagine attempting to keep a raw excavation pressurized with breathable air, so any human involvement will be in pressure suits.

Mining droids?  Exactly how far into the future are we talking about?
As far into the future as self driving cars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/05/2017 01:31 am
I don't think compression is /more/ compatible with ISRU materials. Tension often allows you to be more efficient structurally, as compression often yields by buckling (not actual compressive failure) and buckling doesn't occur in tension. And there are good ISRU materials for tensile members, such as basalt fiber (stronger than fiberglass), UHMWPE (one of the strongest materials known), steel, etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/05/2017 02:13 am
Small roadheader dug colony.  This would be build just after the first habitats from Earth.

The hangar is open, not a pressure building.

Millions? Billions? Quadrillions?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/05/2017 04:35 pm
Small colony in a crater.
The shelf is made from tailing extracted in the colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/05/2017 09:55 pm
More views
Title: Re: Envisioning Amazing Martian Habitats
Post by: Aussie_Space_Nut on 01/06/2017 01:12 am
I like this vision!

I think you need a pressurised garage as well. Doing serious maintenance with spacesuit gloves on would be a real pain. Not impossible, true, but hard. Yes you would have to be careful about toxic dust, but being able to work in an almost shirtsleeve environment would be a massive bonus.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/06/2017 07:52 pm
Here is another view of the base crater.

A launch pad has been build with a exhaust trench for take off.  This was not present for the first few flights.

At the rear of the crater, the wall shows the large excavation done to reach an ice rich layer and separate thin calcium carbonate layer.  This combination was the impulse for the choice of this small 1,6 km crater in the Huygens region.  The tailings from the excavation of the habitats have created wide ledges used as lay down areas and have also been used to create access roads.  Besides the excavation is the first base, build from modules brought from the Earth and partially buried.

The calcium carbonate and the ice are used to create concrete to line the caves and create other structures.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/06/2017 09:32 pm
While replying to ZodiacChris, I came up with a variant on his suggestion: Picture of a "cup" inside a depression/crater/excavation/whatever/don'tcare, made from a water/airtight compressive material. (On Earth you might use reinforced concrete with a liner or an appropriate sealer additive.)

.....

But what happens if the internal pressure is juu.uust right...?

I don't think anybody will feel comfortable about living in a habitat that depends on 1) a revolutionary new construction method and 2) the internal pressure being "juu.uuust right"...

Going to Mars is revolutionary enough in itself. Upon arrival tried & tested and scalable construction techniques (like tunnel-building) make more sense than futuristic domes and experimental ice buildings / ice roofs.   

Small roadheader dug colony.  This would be build just after the first habitats from Earth.

Lovely renderings!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/07/2017 02:07 am
Here is another view of the base crater. [...]
At the rear of the crater, the wall shows the large excavation done to reach an ice rich layer and separate thin calcium carbonate layer.

And IMO, that would always be the primary site of that settlement. Inside that excavation, or using the spoil. Why would you have two separate excavations when only one is necessary?

Most "dugout" homes at Coober Pedy started life as opal mines.

A launch pad has been build with a exhaust trench for take off.

This brings up a point from an older thread again, how do you move the ships around. You aren't going to waste mass bringing in a TEL capable of carrying BFS.

But what happens if the internal pressure is juu.uust right...?
I don't think anybody will feel comfortable about living in a habitat that depends on [...] the internal pressure being "juu.uuust right"...

The "just right" is a fairly broad margin based on the mass of the water-layer. It's no more exact that the air pressure or the oxygen percentage.

I was emphasising it because I wanted confirmation the roof really would be flat if the pressure was roughly the same as the mass/area of the roof. (Lamontagne thought so? Do you? I'm still a little wiggy on it.)

As for maintenance, as Lamontagne noted, all it needs is a pump.

[Edit: What I like about it is that, unlike proposed domes, none of the materials are under tension. Even the membrane can be much weaker than a dome material, hence your choice of materials expands. (It would need to be strong enough to support itself while empty.)

Once filled, in sync with the pressurisation of the internal volume, there would presumably be a safety valve such that if the internal air pressure drops (for whatever reason), the water in the membrane-layers will self-drain into an emergency tank, keeping the roof stable. Indeed, that might be a way of dealing with air-pressure changes due to thermal variation.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/07/2017 02:21 am
I bet they'll just take off from a bare pad like F9Rdev1. Could be just dirt, or perhaps the dirt would be stabilized with like a wire mesh or something.

They will need cranes and such eventually, of course.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/07/2017 02:39 am
Here are some views of the underground tunnels.

There is a first small underground base, with about 3.4 x 3m tunnels and the larger second base, with 9x7m tunnels and a large 30m wide hall (suitable for tennis courts ;-).
I guess it would just go on from here.
The first base of all is just assembled from prefab modules.

Really, it all depends on the soil and rock.  In this case, I presumed the rock layer that is adequate for a habitat is different from the ice layer and the calcium carbonate layer.  For example, the calcium carbonate layer might just be 600mm to 1m high.  But if mining could be combined with habitat making, sure, great.

In case you didn't guess, the crater used for the model is meteor crater in Arizona.

There is a huge solar farm just above the ledge of the crater.  Or a nuclear reactor somewhere nearby.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/07/2017 02:46 am
I bet they'll just take off from a bare pad like F9Rdev1. Could be just dirt, or perhaps the dirt would be stabilized with like a wire mesh or something.

They will need cranes and such eventually, of course.

The stage illustrated here is after the initial dirt pads, but before really large scale installations.  This is still a small village setting.  I expect the full scale colony will expand rapidly out of the crater.

The scale of habitation around meteor crater on Google Earth in interesting and puts all this in perspective.  It's smaller than Windslow Arizo, a small 10000 people town nearby.

When the ships are lightly fueled, they could perhaps just hover over to a new pad?





Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 01/07/2017 02:50 am
I bet they'll just take off from a bare pad like F9Rdev1. Could be just dirt, or perhaps the dirt would be stabilized with like a wire mesh or something.

They will need cranes and such eventually, of course.

The stage illustrated here is after the initial dirt pads, but before really large scale installations.  This is still a small village setting.  I expect the full scale colony will expand rapidly out of the crater.

The scale of habitation around meteor crater on Google Earth in interesting and puts all this in perspective.  It's smaller than Windslow Arizo, a small 10000 people town nearby.

When the ships are lightly fueled, they could perhaps just hover over to a new pad?

Depending on the accuracy of the landing system, the ship can land on the launch pad. The exhaust trench would help with landing too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/07/2017 03:57 am
I bet they'll just take off from a bare pad like F9Rdev1. Could be just dirt, or perhaps the dirt would be stabilized with like a wire mesh or something.

They will need cranes and such eventually, of course.

The stage illustrated here is after the initial dirt pads, but before really large scale installations.  This is still a small village setting.  I expect the full scale colony will expand rapidly out of the crater.

The scale of habitation around meteor crater on Google Earth in interesting and puts all this in perspective.  It's smaller than Windslow Arizo, a small 10000 people town nearby.

When the ships are lightly fueled, they could perhaps just hover over to a new pad?
I think a crane at that point in development is to be expected. They'll need it for construction anyway. And remember they'll be using cranes for that purpose on Earth, and BFS will be much lighter in Mars' gravity and when unloaded.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 01/07/2017 04:13 am
Here are some views of the underground tunnels.

....

There is a huge solar farm just above the ledge of the crater.  Or a nuclear reactor somewhere nearby.

Maybe you can installed a nuclear reactor in an ITS space ship and landed away from the village site with deplorable radiator wings. Of course the reactor gets fueled and  goes critical after the ITS powerboat have planted on the Martian surface. Does stringing about several kilometers of power cable on the Martian surface seems doable?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/07/2017 05:00 am
Here are some views of the underground tunnels.

....

There is a huge solar farm just above the ledge of the crater.  Or a nuclear reactor somewhere nearby.

Maybe you can installed a nuclear reactor in an ITS space ship and landed away from the village site with deplorable radiator wings. Of course the reactor gets fueled and  goes critical after the ITS powerboat have planted on the Martian surface. Does stringing about several kilometers of power cable on the Martian surface seems doable?
Well, you doubled the cost of the reactor by planting it in a single-use BFS...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 01/07/2017 05:26 am
Here are some views of the underground tunnels.

....

There is a huge solar farm just above the ledge of the crater.  Or a nuclear reactor somewhere nearby.

Maybe you can installed a nuclear reactor in an ITS space ship and landed away from the village site with deplorable radiator wings. Of course the reactor gets fueled and  goes critical after the ITS powerboat have planted on the Martian surface. Does stringing about several kilometers of power cable on the Martian surface seems doable?
Well, you doubled the cost of the reactor by planting it in a single-use BFS...
An ITS SC near retirement after several trips to Mars. The early  ITS SC will not have a long service life if SpaceX improves them at their current iteration pace.
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 01/07/2017 06:48 am
It's obvious a lot will depend on the geology of the landing area.

Logically the simplest starter approach is to tunnel into the side of a big mass of rock IE the base of a cliff or crater. The down side is very little natural light and if you have 1 entrance in a fire in that area will get nasty. Given the NASA estimate that growing enough food will take around 45Kw per person for artificial light natural light for culture (agre, hydro, perma or whatever) is quite important. And let's not get carried away. 4m of regolith is expected to be fine. Except for meteorite impacts, which NASA report at 298 over the size of 3.9m over a year.

But for something "amazing" I quite like the idea of a circular atrium cut into the ground with a gently sloping ramp around the outside with individual units going off from it and a shallow dome over the top. This would allow a large shared space while individual units can be made air tight (defense in depth). I would also plan a second entrance for all living spaces due to the risk of fire.

I suck at rendering but to give some idea of what I have in mind here's an interior of the Atlanta High Museum of Art

http://www.urbansplatter.com/2015/01/high-museum-art-richard-meier-atlanta/

This may look familiar as it was used as a location in the film "Manhunter."

BTW I think people should check what the actual colors of Mars are. Those will be what you will be look out of your EVA suit at.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 01/07/2017 07:40 am
This brings up a point from an older thread again, how do you move the ships around. You aren't going to waste mass bringing in a TEL capable of carrying BFS.

Just to pull out one tiny nit to pick at, 'cuz I've had this idea rattling around my head since not long after BFR was new here, It might make a lot of sense to spend the mass to bring the T, but not the EL. Something to move ships around early on could be less costly than building well-spaced landing sites for every one that might be landed at once.

The ITS is pretty lightweight bone-dry empty and without cargo. Not horrible even with cargo still in. (150/600T). And lower gravity sure doesn't hurt.

Not suggesting something like the below would work at all off-the-shelf, But it's rough idea of where to start for size/weight/payload.

This: http://www.trucks4trailers.com/trucks/detail/772/scheuerle-spmt/ (http://www.trucks4trailers.com/trucks/detail/772/scheuerle-spmt/) is 1.25H X 2.5W X 9M long and 26 tons. 270 ton capacity. Three ought to pack into the cargo section without too much trouble and only cost about 1/4 of the payload. Add in powerpacks (Electric of course, or hook up to the ship for a bit of methane.) And either jacks that lift from the ship/booster attach points so it can be lifted and each transporter rolled under a landing leg or a bolt-together frame that lifts from the same attach points.

Bolt the lift frame together, Roll the transporters under it and pick up and drive. Clever design of the lift frame might allow it to be split into sections attached to each transporter. Less work next time and it could set the ship down on a launch mount that lets the legs be re-stowed on the ground before takeoff.

And the total cargo capacity of this thing is high enough to move with a full fuel load (Mars gravity.) if the road underneath will put up with it. Use one ship as a huge tanker truck for the one that's launching and the pads don't need their own fuel storage or piping.

That got long all of a sudden.   ???
And possible getting more than a little off-topic. But this could move from a flat landing to (flame-trenched) launch pad, So...

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/07/2017 03:41 pm
I really don't see the need for multi-ton heavy equipment to move the ITS on Mars. It is already standing on legs. Just slide some roller dollies (or "skates") under each leg and move it along on metal plates that are shifted along as necessary over prepared ground. Rollers like these: http://www.hevihaul.com/dollies/utility-roller-dollies.cmsx  Slow and safe does it.

If the Egyptians could do it, I don't see why first generations Martians can't. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/07/2017 03:46 pm
In the early days, yeah, don't need cranes.

But once you start building that glass dome Musk is so fond of, you'll probably want a good crane anyways. SpaceX uses cranes all the time on Earth, and on Mars they can be ~1/3rd as massive for the same capacity (and that's before you switch out steel for aerospace materials like carbon fiber and use regolith as ballast).

Cranes are handy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/07/2017 04:26 pm
I really don't see the need for multi-ton heavy equipment to move the ITS on Mars. It is already standing on legs. Just slide some roller dollies rollers (or "skates") under each leg and move it along on metal plates that are shifted along as necessary over prepared ground. Rollers like these: http://www.hevihaul.com/dollies/utility-roller-dollies.cmsx  Slow and safe does it.

If the Egyptians could do it, I don't see why first generations Martians can't.

Yep, this will do the trick for a while.  Adopted.  And nothing to model!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/08/2017 05:03 pm
A roadheader, a Volvo mining truck and a modified truck with a microwave sintering head.
The sintering head is a powerful microwave emitter, designed to melt the very dry rockface and transform it into a form of glass finish.  For air tightness, spalling reduction and easier construction.

The truck carries batteries, a power system and a cooling system.  All the equipment is battery powered with electrical drives.

The rubber tires would be replaced with a metal equivalent.

You'll probably want lots of redundancy, at least at first. Instead of seperate mining truck and roadheader, you could dispose of the  roadheader's conveyor belt and include a dumping bucket instead. Having an extra self-dumping roadheader would probably be more economical, as both would permanently be working, as opposed to having a mining truck just sitting around waiting to be filled. With multiple multi-purpose vehicles of the same design, you would also need less variety of spare parts, and if the worst comes to the worst, you could cannibalize unrepairable machines for spare parts for the rest of the fleet. It would seem that the basic roadheader design could also be used as a crane and a bulldozer too without too much adaption. Half a dozen of those, along with a decent amount of spare parts might just about last out until the next synod can resupply with new spare parts.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/08/2017 05:47 pm
Here are some views of the underground tunnels.

There is a first small underground base, with about 3.4 x 3m tunnels and the larger second base, with 9x7m tunnels and a large 30m wide hall (suitable for tennis courts ;-).
I guess it would just go on from here.
The first base of all is just assembled from prefab modules.

Really, it all depends on the soil and rock.  In this case, I presumed the rock layer that is adequate for a habitat is different from the ice layer and the calcium carbonate layer.  For example, the calcium carbonate layer might just be 600mm to 1m high.  But if mining could be combined with habitat making, sure, great.

In case you didn't guess, the crater used for the model is meteor crater in Arizona.

There is a huge solar farm just above the ledge of the crater.  Or a nuclear reactor somewhere nearby.
Suggestions , have a tunnel going up in the back for escape if needed. Also connect each of the tunnels at the ends to each other.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/08/2017 07:21 pm
There's probably no need to bring an unpressurised hanger either. Possibly one of the first things that you would do after first arrival is to use the multi-purpose vehicles to excavate hangers in the cliffside, which would offer a degree of radiation protection. Possibly with a curtain seal to keep dust out, if that's an issue. Maybe the very first amazing habitats would be more akin to motorhomes. It might be preferable to sleep in the vehicles in the excavated hangers so as to reduce radiation exposure, whilst returning to the main ship for socialising, and to escape the claustrophobia and monotony of the "motorhome".

The multi-purpose vehicles may have living areas like some of the Soviet Antarctic vehicles of the past.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/08/2017 08:07 pm
You'll probably want lots of redundancy, at least at first. Instead of seperate mining truck and roadheader, you could dispose of the  roadheader's conveyor belt and include a dumping bucket instead. Having an extra self-dumping roadheader would probably be more economical, as both would permanently be working, as opposed to having a mining truck just sitting around waiting to be filled. With multiple multi-purpose vehicles of the same design, you would also need less variety of spare parts, and if the worst comes to the worst, you could cannibalize unrepairable machines for spare parts for the rest of the fleet. It would seem that the basic roadheader design could also be used as a crane and a bulldozer too without too much adaption. Half a dozen of those, along with a decent amount of spare parts might just about last out until the next synod can resupply with new spare parts.

Great post.

This mega-roadheader is probably overkill for the initial phase of Mars colonization, but I was intrigued by the closed cab. A pressurized closed-cab elctrically-driven roadheader would be great on Mars!

https://youtu.be/QyE5kAothQ4

To use a removal truck of a basically similar construction and employing many of the same parts is a very good idea.

So, Sandvik, how about getting some of your engineers to look into a Mark I Mars roadheader in their spare time? I'd love to see their proposal... :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/08/2017 08:59 pm
I'm certainly not one for art and design, so please excuse my frankenstein mashed up picture. I'm imagining something like a fleet of these "multi-purpose-self-dumping-roadheader-pressurised-habitat-vehicles".

Actually, with a well positioned cab and bucket, you might get a good degree of radiation protection outside by just filling the bucket with regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/08/2017 09:35 pm
Great mash-up Dao! - You even got the viewing angle pretty much lined up. I approve and now the Sandvik engineers have a first draft to work on :-)

I cannot help but find it slightly ironic that a marvel of futuristic rocketry as the IST may end up transporting a positively medieval-looking roadheader to Mars...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/08/2017 09:47 pm
Thanks, Oerstad, I was lucky to find pictures at the right angle. One thing that might not be accurate is the caterpillar tracks. It seems that the consensus is that a six wheeler would be more practical?
Title: Re: Envisioning Amazing Martian Habitats
Post by: wes_wilson on 01/09/2017 01:43 am

-Underground volume is cheap.  It's making that volume leak proof that is expensive.
-If lavatubes are not airtight, sealing them will negate all the savings because of the cost of the walls.
-We don't need airtight rock, we need to be able to build an airtight membrane with insitu resources.  All we need is loadbearing rock.


The deeper you go, the easier it is to make things leak proof as the atmospheric pressure increases naturally with depth.  Maybe another interesting analysis would be where you slant two steeply angled shafts (say 35%) down several kilometers and then carve out all your tunnels and hab spaces at a depth where the natural atmospheric pressure is high enough that already existing mine equipment and techniques (like roof bolting and long wall machinery) can be used to make very large volumes. 

No airlocks to fail either, gravity is your airlock.  Just get in a airtight rover and drive up the angled shafts to the surface; drive back down when you're done. 





Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/09/2017 02:38 pm
Great mash-up Dao! - You even got the viewing angle pretty much lined up. I approve and now the Sandvik engineers have a first draft to work on :-)

I cannot help but find it slightly ironic that a marvel of futuristic rocketry as the IST may end up transporting a positively medieval-looking roadheader to Mars...

Great mash up, but I feel it is not as practical as using trucks for hauling.  The roadheader usually moves a few meters per hour as is digs up the tunnel face but the truck(s) needs to move at an average of about 5 km/hour, so a much higher transit speed, perhaps 10 km/hr, or about 1000 times faster..., explaining the track vs wheel question.
The roadheader has an empty weight of about 120 tonnes while a standard truck weight a little less than 10 tonnes.
3 small 4m3 trucks (about 1/3 the size of a 10 wheel truck we see on the roads) could service a roadheader producing 50m3/hr of space.  These trucks would weigh about 4-5 tonnes each. 
If we are very lucky and the rock is just right we might produce 150m3/hr of rock at the roadheader, and need 4 standard trucks.  This setup would produce up to 3m of 9x6 tunnel per hour so, guessing at 4000 hours of production per year, 12 km of tunnels per year.  The trucks would then haul 1.5 millions tonnes of rock per year, and run somewhere between 15 and 25 000 km per year.  Which is huge for Mars, but sub standard here on Earth.

It might be difficult to get these production rates out of battery electrical trucks though, unless ore hauling is less energy intensive on Mars than on Earth, or they are equipped with batteries than can be switched out every few hours.  I'm guessing at 200 kWh per tonne for the batteries.  Alternatively, we could have one truck more in the circuit, and the trucks would spend 20-25% of their time at a charging station.  The Roadheader can be connected by a power cable and has no need for batteries.




Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/09/2017 04:34 pm
I think a modified rover might make a great automated/remote controlled small ore hauler.
About 4m3 or 10 tonnes.  And lots of commonality.

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/09/2017 05:44 pm
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Clearly designed for vehicles, not people.

I also incorporated other concepts I have in mind - the up-sloped/stepped design, the "central creek".

This all assumes of course that water is easy to come by, which I think is getting more certain by the day.

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/09/2017 05:55 pm
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

It may, but I am not sure it would be easier than an airlock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/09/2017 06:08 pm
Vehicles will rarely get in and out of habitats, if ever. They will attach to docking ports.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/09/2017 06:23 pm
Vehicles will rarely get in and out of habitats, if ever. They will attach to docking ports.

Doubt it.  Vehicles need maintenance.  Construction vehicles, almost constantly.

Also, some vehicles carry external instrument or other loads.

You don't want to do any of that in vacuum suits.


Plus, there will be plenty of vehicles, and having a docking port for each one means tens and tens of holes in the colony, each with a gate that had better not leak, and again - they are active devices that can fail, and failure is very dangerous.

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/09/2017 06:33 pm
Lemme list my considerations then, in comparison to regular mechanical airlocks.  Vehicle ports are better, but they don't replace the core functionality of getting a vehicle indoors.  They can have their use for passenger rovers, some of the time.

Remember also Subtropolis.  It clearly shows that having underground caverns large enough for maintenance garages is not a problem.

---

Here's what worries me about a large mechanical vehicle-sized airlock.

It's two very massive gates, that have to open and close constantly. The doors themselves must hold pressure across a large cross-section, so are very heavy.  Therefore the mechanism is massive too.

The distance between the doors must fit the largest vehicle, and so pump-up and pump-down times are high.

If there's a convoy of vehicles, it's one at a time (or make the chamber even larger.

If one of them jams, the system is down.  If there's worst-case malfunction, the entire colony section is instantly dead, so you need a third, same size, emergency door.  Airlocks should never fail that way, but you need to consider everything, including even sabotage - it's a very weak spot, compared to other things that endanger the colony.

In contrast:

- This thing is 100% passive. There's literally no way it can "break" or "Jam", other than some slow water loss mechanism.

- It's even extremely hard to sabotage. You literally need to get rid of tons and tons of water, and the inertia is huge.  If the water level drops, you can still close the emergency door, but you have ample warning.

- No pump-up or pump-down times. Multiple vehicle can drive through one after the other.

- It controls dust contamination.  With heavy vehicles going in and out, that's a real problem, considering that the rest of the colony is a fully closed system.

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/09/2017 07:01 pm
Google image search "subtropolis"

Seems like a much "roomier" alternative, and one that is continuously expandable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/09/2017 07:54 pm
Vehicles will rarely get in and out of habitats, if ever. They will attach to docking ports.

Doubt it.  Vehicles need maintenance.  Construction vehicles, almost constantly.

Also, some vehicles carry external instrument or other loads.

You don't want to do any of that in vacuum suits.


Plus, there will be plenty of vehicles, and having a docking port for each one means tens and tens of holes in the colony, each with a gate that had better not leak, and again - they are active devices that can fail, and failure is very dangerous.

I agree with maintenance requiring vehicles to get into a pressurized volume. Maintenance would be done in a building that can be pressurized and unpressurized as a whole. That building may or may not have a direct access to the main living quarters, but would be a separate pressurized volume. No point to get dust into the living quarters that way.

The area where vehicles dock, would be designed like an airport terminal. A long stretched area with docking ports along the sides. Again that area would be separated from the main living area by airlocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/09/2017 08:06 pm
Vehicles will rarely get in and out of habitats, if ever. They will attach to docking ports.

Doubt it.  Vehicles need maintenance.  Construction vehicles, almost constantly.

Also, some vehicles carry external instrument or other loads.

You don't want to do any of that in vacuum suits.


Plus, there will be plenty of vehicles, and having a docking port for each one means tens and tens of holes in the colony, each with a gate that had better not leak, and again - they are active devices that can fail, and failure is very dangerous.

I agree with maintenance requiring vehicles to get into a pressurized volume. Maintenance would be done in a building that can be pressurized and unpressurized as a whole. That building may or may not have a direct access to the main living quarters, but would be a separate pressurized volume. No point to get dust into the living quarters that way.

The area where vehicles dock, would be designed like an airport terminal. A long stretched area with docking ports along the sides. Again that area would be separated from the main living area by airlocks.
I'm fine with some docking ports, but that bit about depressurizing the hangar...  It means all the tools (and grease cans, and tool chests) need to be vacuum proof.

I think key to normalization of life in a colony is as little vacuum as possible.

Get as much work done under pressure, and as much work volume permanently pressurised, so it is fully a shirtsleeve environment.

Drive-through helps.  Less operations and less waiting while driving in and out.

Literally - load stuff on the back, hook up a trailer, etc - and drive out.

If a hitch is mis-behaving - you're right there to apply tools.

Just think about all the little things that constantly occur.  Rocks stuck in the suspension, bent fenders, broken lights, hydraulic leaks...  Constant greasing to keep the dust out...


If you can't just see it and fix it, every small task becomes complex.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/09/2017 08:11 pm
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Clearly designed for vehicles, not people.

I also incorporated other concepts I have in mind - the up-sloped/stepped design, the "central creek".

This all assumes of course that water is easy to come by, which I think is getting more certain by the day.

It's cool! I think evaporation and sublimination in a freezing near vacuum will necessitate an airlock and kill the utility of it.  Additionally, unless the water is heated (which contributes to evaporation and sublimination, eventually, your ice plug would get too thick for a vehicle to plow through.
The entrance is oriented so that it is permanently shaded.  We know ice exists in these conditions.

With vehicles popping in and out, you'll get some water-cooling slurry, and you'll lose some water.  I think the quantity will be minimal compared to the water used by the colony.

With ice being an insulator and floating, and some heat coming in from the colony, I think you'll be fine.  I ice plugging is a concern, then we're fine, it's easily solvable by circulating the water - but I doubt it's necessary.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/09/2017 08:35 pm
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Just checked, it works fine in my toilet ;-)

That's a fun, creative solution. I doubt if it will work, but definitely we need to think about practical light-weight dependable airlocks, because they will be a key requirement for a Mars colony. Good thing is that we have a lot of air-lock experience here on Earth, so I definitely don't think it will be a long pole in the tent.

My idea is that the main tunnel will be dug in  a vacuum, exactly to get around the problem of hauling detritus out through an airlock. However, I guess using a roadheader in a vacuum presents its own host of problems as well...

Whereas the main tunnel remains in vacuum the side rooms that are excavated along the way can be progressively lined and pressurized. According to the evolving needs the side rooms can be interconnected, remain in vacuum or be pressurized, and generally serve all sorts of purposes.

It would be really neat to have a fast-working lossless airlock. I think it should be possible at egress to not vent into the outside vacuum but into a bottle collecting the breathable air, which can then be reused for a later ingress. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/09/2017 08:58 pm
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Just checked, it works fine in my toilet ;-)

That's a fun, creative solution. I doubt if it will work, but definitely we need to think about practical light-weight dependable airlocks, because they will be a key requirement for a Mars colony. Good thing is that we have a lot of air-lock experience here on Earth, so I definitely don't think it will be a long pole in the tent.

My idea is that the main tunnel will be dug in  a vacuum, exactly to get around the problem of hauling detritus out through an airlock. However, I guess using a roadheader in a vacuum presents its own host of problems as well...

Whereas the main tunnel remains in vacuum the side rooms that are excavated along the way can be progressively lined and pressurized. According to the evolving needs the side rooms can be interconnected, remain in vacuum or be pressurized, and generally serve all sorts of purposes.

It would be really neat to have a fast-working lossless airlock. I think it should be possible at egress to not vent into the outside vacuum but into a bottle collecting the breathable air, which can then be reused for a later ingress.
:)  I wasn't even thinking about doing this during excavation, but now that you mentioned it....

If there's access to an aquifer, maybe the material can be conveyed in slurry form, out to the open... (The tube will need a smaller dip in it, since rho is higher)

It can then maybe be separated outside...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2017 12:53 am
A truck garage for the larger colony.

The airlock doubles as the truck wash and warm up section.  Even today, in northern climate mining garages, they do not work on the trucks in winter time before they a re-washed and dried down.  Among other reasons, a block of ice falling of the top of a 350 ton mining truck can kill someone.

The doors are essentially large knife gate valves, rather like the doors used on dams for flow control.  These can work against large pressures and air fairly water tight.  Failure is extremely unlikely, as 'robust' just does not do them justice, as far as description goes.

A large centrifugal vacuum pump/compressor would be used to empty the airlock to an economical value (cost of air vs cost of compression).




Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/10/2017 01:31 am
Or how about a retractable pressurized tent. Much easier/cheaper than an elevator.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/10/2017 01:41 am
A truck garage for the larger colony.

The airlock doubles as the truck wash and warm up section.  Even today, in northern climate mining garages, they do not work on the trucks in winter time before they a re-washed and dried down.  Among other reasons, a block of ice falling of the top of a 350 ton mining truck can kill someone.

The doors are essentially large knife gate valves, rather like the doors used on dams for flow control.  These can work against large pressures and air fairly water tight.  Failure is extremely unlikely, as 'robust' just does not do them justice, as far as description goes.

A large centrifugal vacuum pump/compressor would be used to empty the airlock to an economical value (cost of air vs cost of compression).

That's the kind of "massive" doors I was trying to avoid.  Not just the mechanism - the whole structure around them.

Even in semicon equipment, where the gate valves are wafer-sized and operate in clean room conditions, they are a RPiTA.  A 12'x12' gate valve, that is exposed to Mars surface conditions?  boy oh boy.

I was saying - dig a ramp sloped down, slope back up, fill with water, and you have an air-lock.  No anchoring against pressure, no seals between the doorjamb and the rock, no seals between the door and the doorjamb, no hydraulics and power, and really no failure modes - just drive through.

Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 01/10/2017 04:07 am
How dense on average do you imagine a vehicle which can "drive through" water (i.e. without floating)? >1 ton/m^3?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/10/2017 04:54 am
A truck garage for the larger colony.

The airlock doubles as the truck wash and warm up section.  Even today, in northern climate mining garages, they do not work on the trucks in winter time before they a re-washed and dried down.  Among other reasons, a block of ice falling of the top of a 350 ton mining truck can kill someone.

The doors are essentially large knife gate valves, rather like the doors used on dams for flow control.  These can work against large pressures and air fairly water tight.  Failure is extremely unlikely, as 'robust' just does not do them justice, as far as description goes.

A large centrifugal vacuum pump/compressor would be used to empty the airlock to an economical value (cost of air vs cost of compression).
Nice, now each of the side tunnels are connected at their ends ( added safety and ease to get to another tunnel ).

CO2 displaces O2. Could fill the truck garage with CO2, O2 would rise. Then pump the upper area out with the O2 and then open the door ( only vent CO2 back out to Mars atmosphere ). Or crew could wear a rebreather over the nose and mouth  when in the garage.

For the door it could open outward. Well balanced it would not take much energy to open or close, similar to the Panama lock gates. Could be sealed with an inflatable gasket.
Scroll down to the section labeled  "The gates"
https://en.wikipedia.org/wiki/Panama_Canal_locks
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/10/2017 05:04 am
How dense on average do you imagine a vehicle which can "drive through" water (i.e. without floating)? >1 ton/m^3?
Good point, but solvable...

I think most construction equipment sinks easily...

Batteries are heavy...  Pressurized cabins too, but they enclose  a fair amount of volume...

Otherwise needs a belly hook...   

Good point to watch for  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 01/10/2017 05:44 am
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Also discussed here. This thread was about keeping water under an 'oil' layer, where any material that floats on top was considered. You only need the pressure of a few hundred kg/m3 to prevent the water boiling off. So potentially less than a meter thick of this other material. You would need something that was anti-freeze, less volatile than water, clear, did not mix with water and so on.

The thing that hasn't been discussed in detail is using this as an airlock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Semmel on 01/10/2017 07:58 am
Not convinced meekGee:

* Currently, Mars vehicles need to keep pressure in. With the water on the outside, it also need to sustain pressure from outside. So that has probably many design decisions not present in surface vehicles that are not build for that water airlock. So if you are going with that idea, all vehicles need to have these features.

* Vehicles need to operate in near vacuum on mars, in a very very dry environment in non-corrosive CO2 atmosphere. Going through the water will mean that they are susceptible to a wet and ultimately corrosive environment. Lubrication of moving parts in near-vacuum with the martian dust present is very tough in the best of times. Making them work submerged in water is even tougher.

* When vehicles come out to operate on the surface, the water will ultimately freeze on the outside of the vehicle. Unless you are planning for a drying furnace, you will get problems with water ice everywhere. When vehicles come in from the outside, they will be very cold. They are many tonnes of mass and will require a lot of energy to warm up before they can go into the water without becoming a frozen bulldozer on a stick. So for both directions you need a powerful heating/drying area near the outside water surface which kills your energy efficiency of the system.

* The water will eventually get all murky from dust that vehicles carry inside. So you need a water cleaning facility, filters, or you need to replace the water regularly. The colony needs to have the water cleaning facility anyway for water mining but this will be a big hassle because you cant drain the pool without depressurizing the colony. So you will need to cycle the water constantly.

With all the above, I think an airlock with heavy doors (that hinge inside, so a mechanism failure would close them automatically) seems easier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/10/2017 08:10 am
I like the idea to move out digging debris as slush instead of through airlocks. Provided a simple method to retain the water can be devised.  A LOT of water would be required, it cannot get wasted.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/10/2017 08:59 am
I think we need a lighter system than Panama locks and a simpler system than water airlocks (which though simple in principle come with a lot of issues).

The tent idea is interesting, but how will it work?

I was thinking about some kind of revolving door principle which will make egress and ingress easy but will of course entail a loss of precious breathable air unless used sparingly. Also difficult to envisage in use for truck-sized vehicles.

If we let the tunnel digging operation happen in Mars vacuum it will just be necessary to pressurize the cabs of the roadheaders and removal trucks. That maybe sounds complicated, but isn't it needed in any case, for the initial entrance work on a tunnel? And for other outside work, such as levelling a landing/take-off pad, etc? - My conclusion is that the big machinery really should be designed for work in a vacuum.

After a day's work the vehicles can be parked tightly in a side-room airlock / garage /repair shed for the necessary maintenance. Pressurizing and depressurizing that space once per day will not necessarily entail a big loss of breathable air. I believe the roadheader and trucks will be Bobcat-sized in the initial phase of the colony, so very big airlock doors for the garage won't be needed.       
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 01/10/2017 09:30 am
I was thinking about some kind of revolving door principle which will make egress and ingress easy but will of course entail a loss of precious breathable air unless used sparingly. Also difficult to envisage in use for truck-sized vehicles. 
You could pressurise a hanger with martian CO2. Then you could use another solution for walking from breathable air to hangar air at the same pressure. You could use a small sump or perhaps you could just be momentarily sandwitched between two air-bags. That would mean no airpockets would be carried from one side to the other so no mixing of gasses.

With both sides being at the same pressure, just some fly screen drapes could be enough to minimise much mixing for the second or two that the real door is open. Think of it as something to move from a normal room to a smokey room and back, minimising smokey air getting into the  normal room.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/10/2017 10:18 am
Ah, very good point KelvinZero, that the pressure lock and the air lock need not be one and the same.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2017 01:19 pm
Airlock design:
Considering an airlock 6mx9mx15m=810m3, the power required to empty it from 1 atm to 0,01 atm is about 250 kWh, or at my cost of 1$/kWh 250$.  About 0,3$/m3.

Considering the air is created by compression of Martian atmosphere in the exact reverse process, compressed Martian atmosphere is about 0,3$/m3.  This is 95% CO2, that we will ship over to a fuel processing facility.  This facility will generate excess oxygen, so the oxygen in the atmosphere of the base is a by product of fuel processing.
The Nitrogen, about 2%, can be separated by cooling. This 2% must be moved up to 80% in concentration, or a ratio of 40.  So the atmosphere would cost about 40x 0.3 or 12$ per m3, plus separation costs, so let's guess 20$/m3.  If we can also use the Argon in Martian atmosphere, we might get a nice round number of 10$/m3.
So the airlock holds between 8000$ and 16000$ of atmosphere.
Considering this value, I think it's worth the cost to bring heavy doors from Earth, at the base cost of 260 000$ per tonne of equipment to Mars than I used for my other calculations.  The doors are about 4mx4m.  Since most of us are willing to believe that Martian domes are possible, and that these will weigh less than 100 kg/m2, I suggest we use this number for the doors, putting them at 1.6 tonne each(frame included).  We could have redundant doors for the airlocks, so 4 doors per airlock, putting the price of these doors at about 6.4 x 260 000$ = 1,7 m$.  The cost of the airlock itself would be about 100 000$, at roadheader costs.
The usual spreadsheet is joined ;-)
The airlock need not operate very often.  If it is open once a day, and that the airlock holds 2 vehicles, we can maintain 14 vehicles at a maintenance frequency of once a week.  If the maintenance is once a month we can maintain a fleet of 60 vehicles with our garage.  With 6 bays, the vehicles can stay 3 days in maintenance.

For small vehicles, at a maintenance rate of once every 2 months and 4 vehicles per airlock cycle, we could maintain 240 vehicles with our garage and our single air lock.

I suggest that the transit airlocks be external ones, capable of dozens of cycles per day.  Works for aircraft in airports, after all.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/10/2017 01:27 pm
Yet another reason to not operate at full sea level Earth pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2017 02:10 pm
Yet another reason to not operate at full sea level Earth pressure.
Have you seen any mention of using argon as well as nitrogen in the Martian base atmosphere?  There's just as much argon as nitrogen, and it's inert, so I would guess that for humans they might be equivalent.  Don't know about plants and bacteria.  I guess than when you extract the nitrogen the argon comes along as well?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2017 02:18 pm
I was thinking about some kind of revolving door principle which will make egress and ingress easy but will of course entail a loss of precious breathable air unless used sparingly. Also difficult to envisage in use for truck-sized vehicles. 
You could pressurise a hanger with martian CO2. Then you could use another solution for walking from breathable air to hangar air at the same pressure. You could use a small sump or perhaps you could just be momentarily sandwitched between two air-bags. That would mean no airpockets would be carried from one side to the other so no mixing of gasses.

With both sides being at the same pressure, just some fly screen drapes could be enough to minimise much mixing for the second or two that the real door is open. Think of it as something to move from a normal room to a smokey room and back, minimising smokey air getting into the  normal room.
Once you have an air reserve there is no real point in using CO2, it's just more complex to keep it separated.  The only cost is the cost of creating the low pressure in the airlock, and that is about the same for air as for CO2. Once you have extracted the air from the airlock, and stored it at 1 atmosphere in your base, you just put the same gas back in the airlock to pressurize it.
You could cycle CO2 instead of cycling air, but that seems pointless as you will want to have air reserves anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/10/2017 03:17 pm
Not convinced meekGee:

* Currently, Mars vehicles need to keep pressure in. With the water on the outside, it also need to sustain pressure from outside. So that has probably many design decisions not present in surface vehicles that are not build for that water airlock. So if you are going with that idea, all vehicles need to have these features.

* Vehicles need to operate in near vacuum on mars, in a very very dry environment in non-corrosive CO2 atmosphere. Going through the water will mean that they are susceptible to a wet and ultimately corrosive environment. Lubrication of moving parts in near-vacuum with the martian dust present is very tough in the best of times. Making them work submerged in water is even tougher.

* When vehicles come out to operate on the surface, the water will ultimately freeze on the outside of the vehicle. Unless you are planning for a drying furnace, you will get problems with water ice everywhere. When vehicles come in from the outside, they will be very cold. They are many tonnes of mass and will require a lot of energy to warm up before they can go into the water without becoming a frozen bulldozer on a stick. So for both directions you need a powerful heating/drying area near the outside water surface which kills your energy efficiency of the system.

* The water will eventually get all murky from dust that vehicles carry inside. So you need a water cleaning facility, filters, or you need to replace the water regularly. The colony needs to have the water cleaning facility anyway for water mining but this will be a big hassle because you cant drain the pool without depressurizing the colony. So you will need to cycle the water constantly.

With all the above, I think an airlock with heavy doors (that hinge inside, so a mechanism failure would close them automatically) seems easier.

Of course this has to be a design requirement for the vehicles but it comes practically for free for any industrial built vehicle that needs to be pressure hosed. 

Being electrical, you don't even have to add snorkels.  The one thing that need to be watched for is large cooling fans, since the blades bend.  Any airtight pressure vessel will be fine when submerged.

The utility of this system increases with the usage rate. 10 work parties going out and then back in per day?  20?  Each one consisting of at least 2 vehicles?

How long should they wait for truck-sized airlocks to cycle?

----

As for cleaning the water, sure, but that doesn't factor into the operation of the airlock.  The filters can sit inside the base, or you can send out a truck with a filter on the roof to pick up anything that floats. (?)

----

Ice on the vehicle, I think will go away with a combination of motion, sunshine and vehicle generated heat.

But again, these vehicles will be robust, closer to a construction tractor than a Mars rover.  Not fragile things.

------

Consider this: how long before someone accidentally drives into the airlock door?

Both the door seals and the connection between the doorjamb and the walls must be unaffected.

How massive should it be built? Such a door and it's doorjamb can easily take up an entire ITS (assuming a 12x12' door)

The water airlock has no breakable parts.  It's two slanted ramps.  Can't bend, can't jam, can't form a bad seal, can't lose power, doesn't inherently use any power (well there's the filter, and of course the vehicle has to drive down and up...)

Consider how shitty it is if one door fails to seal and 10 trucks are now stuck outside, so now have to go use the car ports to get the people in, no access to all the external equipment...

And now you need to maintain this 50-ton door.. (just guessing) which will take a week or two, and hopefully won't require changing large parts...


Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/10/2017 05:21 pm
Yet another reason to not operate at full sea level Earth pressure.
Have you seen any mention of using argon as well as nitrogen in the Martian base atmosphere?  There's just as much argon as nitrogen, and it's inert, so I would guess that for humans they might be equivalent.  Don't know about plants and bacteria.  I guess than when you extract the nitrogen the argon comes along as well?
It may help reduce the bends and would make ISRU of the buffer gases a little easier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2017 05:33 pm
Running into the door is a serious problem.  In mining we had flexible doors that could be reset if a truck ran into them, not so on Mars.  Got to think about that one.  Two airlocks would solve the availability question, but the risk of breaking down the door is non trivial.  Probably need a pressure door and a separate safety grid.

The only reason you would drive a truck inside is maintenance.  Even here on Earth, with all the dust on mine sites, even if it's cold you don't drive the truck in.  Manned trucks would need external airlocks that can match the cabin to an pressurized access ramp.
Hose cleaning requires only dust tight NEMA4 enclosures.  These are not water tight and you would get any number of short circuits with complete immersion.  A submarine is not a mining truck, and vice versa.  And any truck on Mars will be self parking and self connecting or Elon Musk will not have been involved. 

No cooling fans on Mars.  Just radiating surfaces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/10/2017 07:32 pm
Garage airlock

Garage connected to an airlock. Compress ambient air when base has excess power into a holding tank. Holding tank releases compressed CO2 into airlock. Airlock door opens to garage. Truck drives into airlock , door then shuts. Some CO2 is displaced into garage area and some garage air will mix with airlock air. CO2 is vented to outside, then outer door is opened. Truck drives out and airlock is ready for a truck to drive in from the outside. Outer door is closed and then CO2 from holding tank is let into airlock. Inner door is opened and truck drives into garage. Some H2O will accumulate in the CO2 holding tank that needs to be removed but can be used by the colony.

Only one compression cycle needed and venting to the outside should reduce time for egress.

Could use small , medium, and large airlocks to reduce air lose and energy costs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 01/10/2017 11:28 pm
One possible class of non-surface but proximate to surface amazing habitats is living inside Martian Yardangs as people have done on Earth for thousands of years, e.g. Cappadocia Turkey.  These natural structures may be exploitable on Mars.  This site, Appolonarus Sulci, is only 12 degrees south of the equator and best of all has a soil containing 7.5% water in the upper centimeters.

http://www.hou.usra.edu/meetings/explorationzone2015/pdf/1043.pdf

"A major advantage to landing a human mission near the Medusae Fossae is the potential to use the formation itself as a source of feedstock for civil engineering projects. The Medusae Fossae represents a vast source of fine-grained, easily mineable material that could be used to build landing pads, berms, roads, habitations, emergency shelters, equipment shelters, etc  In addition, dwellings could be dug directly into the side of yardangs, providing natural protection from temperature extremes, radiation, and small meteors. Volcanic tuff deposits have served as building material for human beings for milennia. Cities such as Rome and Naples sit above extensive tuff quarries and underground tunnels, cisterns, storerooms. In the Cappadocia region of modern Turkey, early Christians built and enlarged underground cities, some of which were capable of housing more than 20,000 people and their livestock..."
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/11/2017 01:07 am
Here is a simple early garage.

The sections are built on Earth but assembled on Mars.
The sequence is: 
1-The circular floor is laid out
2-The rear wall with the airlock is assembled.
3-The machine is moved onto the pad.
4-The pre assembled doors are lifted in place using a small crane
5-The doors are bolted on to the base and to one another.
6- The dome is pressurized.
7-When all is secure, personnel enters through the airlock, tht can serve as emergency refuge.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/11/2017 04:56 am
Running into the door is a serious problem.  In mining we had flexible doors that could be reset if a truck ran into them, not so on Mars.  Got to think about that one.  Two airlocks would solve the availability question, but the risk of breaking down the door is non trivial.  Probably need a pressure door and a separate safety grid.

The only reason you would drive a truck inside is maintenance.  Even here on Earth, with all the dust on mine sites, even if it's cold you don't drive the truck in.  Manned trucks would need external airlocks that can match the cabin to an pressurized access ramp.
Hose cleaning requires only dust tight NEMA4 enclosures.  These are not water tight and you would get any number of short circuits with complete immersion.  A submarine is not a mining truck, and vice versa.  And any truck on Mars will be self parking and self connecting or Elon Musk will not have been involved. 

No cooling fans on Mars.  Just radiating surfaces.

Generally yes about the fans, though forced convection does give you something useful, even at Mars pressures.

The fan example was to show how little it takes to make a vehicle immersion-proof.  Especially if it's electrical.  (And there's less exhaust heat in an electric vehicle to begin with, too).

--

I was trying to find out how much a 12' x 12' vacuum door weighs, but didn't find a suitable vacuum chamber...  only much bigger or smaller...







Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/11/2017 10:57 am
I take it from the current discussion that people realise the Mars vehicles won't be operated in a pressurised environment? Hence they will need to be designed for near-vacuum and surface operation?



(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1400300;image)

Ah, KelvinZero's wetlock re-emerges.

Re: Buoyancy.

It's worth remembering that the issue with buoyancy isn't just overall vehicle buoyancy, but also local buoyancy. Eg, a vehicle might have overall negative buoyancy because of that big heavy bucket/crane/digger on the back, but the front with the cabin will have local positive buoyancy. Meaning the front will want to float, the back will want to sink. In deep water, the vehicle would hang vertically. In a tunnel, the front might wedge on the ceiling.

Given the buoyancy of a vehicle with a pressure-vessel-cab, you might need dense ballast weights designed to sling under the vehicles or attach at custom points, where appropriate for the vehicle type.

Either way, traction might be rubbish enough that you'd want a drag-line conveyor on roof to tow the vehicles in/out. An advantage is that lets you use a steeper tunnel, reducing the amount of tunnelling and the amount of water you need. Nonetheless it does turn movement through the wetlock into a mechanical system, prone to breakdown - the very thing you're trying to avoid.

Re: Water ice layer/water-loss-rates.

If the surface is anywhere near the triple point of water, you won't get a nice frozen layer, you'll get a weird interface that both freezes and boils. This is especially true of your design, since it will pick up heat from the habitat end, and hot-water rises.

(Solid nitrogen demo (http://"https://www.youtube.com/watch?v=E5p2yooC5fY") is the closest I can find.) One of the other interesting things to note is that the rate of boiling increases as the pressure drops. People seem to forget that. Even the rate of sublimation will be higher than you'd expect from experience with ice at Earth-pressure.

The good news is that I'd expect the boiling to turn the ice-layer into slush. Should be easy to push through (ignoring buoyancy issues) regardless of how thick it gets. You might encourage this with a slush-maker.

Re: Mass of airlock doors

Your design has hard-doors on either end to serve as emergency closures. Hence you need to bring big heavy doors capable of withstanding the full pressure difference.

IMO, if a wetlock can be made practical, it has other advantages, but saving on the shipping mass of doors isn't one of them.



As KelvinZero has suggested in previous threads, there might be something that works better than water. Some kind of mineral/silicone oil or an ionic liquid with a low vapour pressure. If you can find a suitable mineral or silicone oil, it would solve the sealing issue (since it doesn't matter if the electrics get soaked in non-conducting oil. However, it may become harder or essentially impossible to ISRU, so you're limited to what you can bring.

(Perhaps immiscible layers. Low density, low vapour pressure layer at the Mars-surface end, to reduce boil-off. Water for the bulk, to allow ISRU for the largest component. And perhaps a mineral oil layer at both ends as a water-displacing wash. So Mars surface, unpressurised hanger, low-vapour-pressure layer, mineral oil layer, water... water... mineral oil layer, pressurised inert atmosphere hanger, finally a personnel "airlock" leading to equal-pressure habitat. For space-suit access to the surface, a smaller version would just be water, with a small low-vapour-pressure layer at the Mars end.)



Alternatively, a combination of the wetlock with an airlock at the Mars-surface end. It shouldn't take too many PSI to raise the boiling point of water high enough to be useful again. So if you have the Mars-surface end slightly pressurised, an airlock from there to the open surface would be easier than from the full habitat pressure. (Faster cycling, lower energy, less wasted gas, less pressure on the doors hence lower mass, etc.)



Hmmm, the vapour pressure of water is  0.6-3kPa between 0-20℃. So if the water is cool (<5℃), then you could let the water vapour build up in a chamber at the Mars-surface end and it should stop the evaporation while still being close to Mars surface pressure. (Close enough for the subsequent "airlock" to be nearly unpressurised.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/11/2017 11:55 am
The garage in its environment, Marsbase1.

Still missing, a boom truck.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/11/2017 01:01 pm
How about a chute for removing excavated regolith? Sealed doors at each end, but no pumps, just fill to the brim with finely crushed regolith and let gravity push most of the air back into the pressurised space. There will still be some loss of atmosphere, so it may or may not be more economical than traditional airlocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/11/2017 01:22 pm
I take it from the current discussion that people realise the Mars vehicles won't be operated in a pressurised environment? Hence they will need to be designed for near-vacuum and surface operation?

I agree. It is really hard for me to imagine that the very few vehicles it is possible to bring to the Martian surface would NOT be capable of operating in a near vacuum.

The tunnelling vehicles (roadheader and possible regolith removal trucks) will necessarily have to begin their tunnelling on the outside surface of Mars. They'll even have to be able to move from the IST to the future tunnel entrance.

Furthermore, the vehicles will probably be multi-purpose and modular, to enable maximum spare parts commonality and maximum usability in case of a partial breakdown. The possibility of swapping and scavenging parts and modules is surely desirable.

All of this points towards vehicles than can operate comfortably and dependably in a Martian vacuum. That will also obviate the need for huge airlock doors and other creative airlock solutions.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/11/2017 01:47 pm
It might increase the longevity of the vehicles to minimise operations in the cold, low pressure environment as much as possible. It could also be easier to repair broken down vehicles in a pressurised environment. I'm not sure if it's worth the effort to pressurise, but I'm open minded. After more infrastructure is in place it may well make some sense to bring less complex vehicles only capable of operating in a pressurised environment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/11/2017 02:35 pm
It might increase the longevity of the vehicles to minimise operations in the cold, low pressure environment as much as possible. It could also be easier to repair broken down vehicles in a pressurised environment. I'm not sure if it's worth the effort to pressurise, but I'm open minded. After more infrastructure is in place it may well make some sense to bring less complex vehicles only capable of operating in a pressurised environment.

Very true that limiting the exposure to cold and vacuum might increase the longevity of vehicles. However, they will have to be able to operate in a vacuum for the initial phases of work and will therefore have to be designed for it.

Also very true that maintenance will surely be easier in a pressurized environment. It won't be available initially unless a prefab garage structure is brought along. I would suggest that it would be better to spend the mass on spares and extra modules (electrical motors, drill-heads, wheels, etc). The first side room of first the tunnel dig should definitely be a pressurized repair shed. By that time I'm sure the roadheader could do with a bit of TLC.

Down the road: yes, everything can be envisaged, even dedicated vehicles that can only work in a pressurized environment. But first things first.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/11/2017 02:58 pm
I don't think they necessarily will have to operate in vacuum, only that they are stable in vacuum for transport. Operating in vacuum means they need a whole lot more complicated heat management, for instance.

even a tunneler may start in an initial small some that is pressurized to make working easier.

Not that there won't be equipment that needs to operate in vacuum, just that it doesn't need to be all of it.

Operating in a pressurized environment means you can basically buy off the shelf electric mining equipment and use it basically as-is, saving time and development money. Maybe with some parts specially prepared for unloading separately, like deflating the tires or greasing their outside to keep them from becoming brittle in vacuum.

For a long time, the Russians operated their electronics in pressure vessels so they could use cheaper stuff that they had available. Only recently have they developed vacuum-rated electronics. So there's a lot to be said for operating in a pressurized environment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/11/2017 03:56 pm
I am convinced that there will be very little off-the-shelf equipment used on Mars. It's just not possible. It would be inconceivable to go to the trouble of delivering equipment to the Martian surface and not ensure that it is absolutely tailormade for Martian conditions. The roadheader will be electrically operated, extremely robust and dependable, modular and easy to assemble, and most importantly have a power-to-weight ratio unlike any Earthly roadheader. Super-light and super-strong. I have no doubt that Musks' newfound interest in tunnelling equipment stems from the fact that he realises that Mars will need equipment unlike anything yet produced.

Of course the roadheader will also be robotic. Pretty evident when you think about it. No need for a pressurized cab and no exposure of a human operator to unnecessary risk. Also, it enables a quite small frontal cross-section so it can fit through relatively small airlocks. Even of KelvinZero's liquid variety  :-)

Seems succesful robotic roadheaders were a thing already back in 1994:
https://ec.europa.eu/research/success/en/mat/0043e.html

The Chinese are doing research on them as well (2008):
http://ieeexplore.ieee.org/abstract/document/4721957/?reload=true


Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/11/2017 04:05 pm
Mining equipment like road headers ARE usually electrically powered, by the way.

But I agree there's a good case to be made for a more weight-optimized design. Replace steel structure with aluminum and/or carbon fiber, for instance.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/11/2017 05:10 pm

But I agree there's a good case to be made for a more weight-optimized design. Replace steel structure with aluminum and/or carbon fiber, for instance.

A lot of research and money may go into making them more lightweight. Possible IMO that it is more efficient to send the first one or two  at least mostly off the shelf, only with needed adjustments for martian environment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 01/11/2017 11:31 pm
It would be really neat to have a fast-working lossless airlock. I think it should be possible at egress to not vent into the outside vacuum but into a bottle collecting the breathable air, which can then be reused for a later ingress.

Might want to use lots of smaller pumps going to common collecting bottles (or separate ones with a crossbar to let you send a pump to more than one bottle), allows for some failures at the cost of slower operation when failed vs no operation, and might make speed easier (lots of medium sized pumps might be easier than one monolithic fast pump)?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/12/2017 12:51 am
A small boom truck and platform, very useful for all construction.

That completes the set, I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/12/2017 01:29 am
A line up of Mars vehicles.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/12/2017 02:57 am
Thunderbirds are go!
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/12/2017 05:06 am
It would be really neat to have a fast-working lossless airlock. I think it should be possible at egress to not vent into the outside vacuum but into a bottle collecting the breathable air, which can then be reused for a later ingress.
Might want to use lots of smaller pumps going to common collecting bottles (or separate ones with a crossbar to let you send a pump to more than one bottle), allows for some failures at the cost of slower operation when failed vs no operation, and might make speed easier (lots of medium sized pumps might be easier than one monolithic fast pump)?

I think one large volume, maybe as large as the airlock or facility to evacuate. No need to pump against high pressure, more energy efficient. Though maybe slower to fill the volume back from low pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/12/2017 12:14 pm
Setting up a temporary garage.
Could this be set up in a day?
How long would it take to secure the dome sections in place?

Regarding pumping out air locks, the power requirements are fairly high, in particular for the last few kPa.   The best place for the air from the airlock would be the colony.  If it's volume is 100 times the airlock volume, then pressure varies by only 1%.  For larger colonies pressure variation becomes trivial.


Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/13/2017 02:15 am
Setting up a temporary garage.
Could this be set up in a day?
How long would it take to secure the dome sections in place?

Regarding pumping out air locks, the power requirements are fairly high, in particular for the last few kPa.   The best place for the air from the airlock would be the colony.  If it's volume is 100 times the airlock volume, then pressure varies by only 1%.  For larger colonies pressure variation becomes trivial.
Instead of a half sphere could it be a half cylinder laid down? Would this result in less wasted area? Airlock on one end for people from the colony and the other end the garage door for the trucks ( equipment ) to egress.

Airlocks-

From the colony to the garage could be a small airlock for people. Person enters the airlock from the colony side. They displace some of the air back into the colony area. The airlock door closes. Person has a rebreather over their mouth and nose. CO2 enters the airlock from the bottom displacing the colony air as the air is sucked up from the top and sent to the colony air recycle system. The air inside the airlock would now be mostly CO2. The other door leading to the garage now opens and the person enters the garage ( no air pressure has changed ). The reverse is done when a person returns to the colony.

For trucks and equipment egress of the garage.

The air ( CO2 ) in the garage is vented to the ambient Mars atmosphere, energy needed ( very low ), opening and closing of a valve. Garage door opens , truck drives in , garage door closes. Compressed CO2 is let in from a storage tank until the desired pressure is reached. When there is excess power for the colony the compressors turn on filling the storage tank(s). This way the colony air lose is low and replacement cost are low. The compressed CO2 is there when needed. When the CO2 from the Mars atmosphere is compressed for storage it might also have the O2 and N2 removed for use by the colony.

The crew in the garage wears a rebreather for breathable air in the CO2 atmosphere of the garage. This also helps keeping out any Mars dust the might be in the garage air. Fans could run to circulate the air in the garage and run it through filters to remove any dust in the air.

From the garage door if there was a tunnel the trucks entering could be blasted with compressed air ( CO2 ) to help remove any dust on them.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/13/2017 02:42 am
Setting up a temporary garage.
Could this be set up in a day?
How long would it take to secure the dome sections in place?

Regarding pumping out air locks, the power requirements are fairly high, in particular for the last few kPa.   The best place for the air from the airlock would be the colony.  If it's volume is 100 times the airlock volume, then pressure varies by only 1%.  For larger colonies pressure variation becomes trivial.
Instead of a half sphere could it be a half cylinder laid down? Would this result in less wasted area? Airlock on one end for people from the colony and the other end the garage door for the trucks ( equipment ) to egress.

Airlocks-

From the colony to the garage could be a small airlock for people. Person enters the airlock from the colony side. They displace some of the air back into the colony area. The airlock door closes. Person has a rebreather over their mouth and nose. CO2 enters the airlock from the bottom displacing the colony air as the air is sucked up from the top and sent to the colony air recycle system. The air inside the airlock would now be mostly CO2. The other door leading to the garage now opens and the person enters the garage ( no air pressure has changed ). The reverse is done when a person returns to the colony.

For trucks and equipment egress of the garage.

The air ( CO2 ) in the garage is vented to the ambient Mars atmosphere, energy needed ( very low ), opening and closing of a valve. Garage door opens , truck drives in , garage door closes. Compressed CO2 is let in from a storage tank until the desired pressure is reached. When there is excess power for the colony the compressors turn on filling the storage tank(s). This way the colony air lose is low and replacement cost are low. The compressed CO2 is there when needed. When the CO2 from the Mars atmosphere is compressed for storage it might also have the O2 and N2 removed for use by the colony.

The crew in the garage wears a rebreather for breathable air in the CO2 atmosphere of the garage. This also helps keeping out any Mars dust the might be in the garage air. Fans could run to circulate the air in the garage and run it through filters to remove any dust in the air.

From the garage door if there was a tunnel the trucks entering could be blasted with compressed air ( CO2 ) to help remove any dust on them.
Yes, it can be made any length by adding extra middle sections.  The half sphere is just the smallest version.
I like washing the trucks because they can be very dirty, and have a lot of grease and oil as well.  Compressed air needs would be huge, and the results very messy. 
Compressing the CO2 requires work, and working in CO2 would be risky.  I know welders hate wearing air intake masks and carrying air tubes, so I expect mechanics would feel the same way.   I expect all compressed CO2 will go to fuel production, and it's not that expensive to compress air, versus all the problems of CO2.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/13/2017 03:01 am
Here is a view of the long garage.

It's exactly the same proportions as the dome garage, just a large number of mid sections, with matching floor beams and plates. The white module between the rover and the garage is a multi connector airlock.  It has 5 doors, or even six in space use, and can serve as an airlock between any number of modules.  I expect the rover would have some sort of pneumatic suspension so it could match exactly with the doors. 


Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/13/2017 04:59 am
Yes, it can be made any length by adding extra middle sections.  The half sphere is just the smallest version.
I like washing the trucks because they can be very dirty, and have a lot of grease and oil as well.  Compressed air needs would be huge, and the results very messy. 
Compressing the CO2 requires work, and working in CO2 would be risky.  I know welders hate wearing air intake masks and carrying air tubes, so I expect mechanics would feel the same way.   I expect all compressed CO2 will go to fuel production, and it's not that expensive to compress air, versus all the problems of CO2.
Compressing the CO2 requires work, and working in CO2 would be risky.
What work? What risk?

The rebreathers also protect the workers from breathing in the dust in the air and from on the trucks.

If a vacuum pump is used to remove the air in the garage before the door is opened were is this air being moved to? Keep in mind the colony might not have the needed power at the time they need to open the garage door to pump down the air pressure. One of the reasons I was looking at precompressed CO2 to refill the garage with air pressure and just venting it when needed. And it should be quicker than pumping down the air.

For cleaning off the dust on the trucks I was thinking of the trucks in a tunnel in front of the garage door. So when the CO2 would be vented out of the garage it would go through a hose with a nozzle on it controlled by a robotic arm to use the CO2 to blow off the dust. Compressed air is used to clean off work benches all the time. This would just be air that is CO2 that is being vented anyway ( no added energy needed other than for the robotic arm ).

What is the height of the garage door and the ceiling height of the garage?
I suggest starting off with an airlock large enough to fit the biggest truck. Then connect a garage, long tub wider than the airlock but not much taller than the trucks ( or eight foot which ever is greater ). On the right side could be work bays to service the trucks. On the left side for example could be high work bays to use lifts when needed. Later could add a tunnel in front of the opening to the airlock, use to spray off dust with air and to reduce dust from blowing in the airlock from outside.

Washing trucks could be done in a wash bay, closed off from the rest of the garage.

Your drawings do look great.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/13/2017 01:16 pm
Compressing the CO2 requires work, and working in CO2 would be risky.
What work? What risk?

To elaborate. We have two alternatives:

1) The airlock uses breathable air from the main habitat. It is evacuated to Mars surface pressure by pumping air back into the main habitat (or at least into a volume-adaptable "lung" module.) To repressurise the airlock, you just vent breathable air back in.

2) The airlock uses Mars CO₂ pressurised up to habitat levels. To evacuate to Mars surface pressure, you just vent the CO₂ to the Mars atmosphere.

It takes as much work to pressurise airlock-2 with Mars atmosphere at habitat-pressure, as it does to lower the (breathable) air pressure inside airlock-1 to Mars pressure. You're pumping exactly the same volume of gas.

The opposite cycle of both airlocks is simply venting. Airlock-2 vents to Mars to lower its pressure. Airlock-1 vents from the habitat to raise its pressure.

However the CO₂ pressurised airlock-2 then requires another system to swap out the pressurised CO₂ with breathable air, but must be designed to prevent CO₂ poisoning of the habitat air supply.

Safe long term CO₂ limits are somewhere around 0.5% of air pressure. Short term, you can tolerate up to 5% before you probably can't work any more and possibly need someone else to help you get to safety.

If you are in a 100% CO₂ environment, think how little leakage around your mask puts you in the danger zone. And how little mixing as people move between the 100% CO₂ environment and the main habitat is required to but stress on the ELCSS.

One of the reasons I was looking at precompressed CO2 to refill the garage with air pressure and just venting it when needed. And it should be quicker than pumping down the air.

The atmosphere of the habitat serves the same goal. When you want to come up from Mars pressure to habitat pressure, you simply open a vent from the habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/13/2017 07:46 pm
Compressing the CO2 requires work, and working in CO2 would be risky.
What work? What risk?

To elaborate. We have two alternatives:

1) The airlock uses breathable air from the main habitat. It is evacuated to Mars surface pressure by pumping air back into the main habitat (or at least into a volume-adaptable "lung" module.) To repressurise the airlock, you just vent breathable air back in.

2) The airlock uses Mars CO₂ pressurised up to habitat levels. To evacuate to Mars surface pressure, you just vent the CO₂ to the Mars atmosphere.

It takes as much work to pressurise airlock-2 with Mars atmosphere at habitat-pressure, as it does to lower the (breathable) air pressure inside airlock-1 to Mars pressure. You're pumping exactly the same volume of gas.

The opposite cycle of both airlocks is simply venting. Airlock-2 vents to Mars to lower its pressure. Airlock-1 vents from the habitat to raise its pressure.

However the CO₂ pressurised airlock-2 then requires another system to swap out the pressurised CO₂ with breathable air, but must be designed to prevent CO₂ poisoning of the habitat air supply.

Safe long term CO₂ limits are somewhere around 0.5% of air pressure. Short term, you can tolerate up to 5% before you probably can't work any more and possibly need someone else to help you get to safety.

If you are in a 100% CO₂ environment, think how little leakage around your mask puts you in the danger zone. And how little mixing as people move between the 100% CO₂ environment and the main habitat is required to but stress on the ELCSS.

One of the reasons I was looking at precompressed CO2 to refill the garage with air pressure and just venting it when needed. And it should be quicker than pumping down the air.

The atmosphere of the habitat serves the same goal. When you want to come up from Mars pressure to habitat pressure, you simply open a vent from the habitat.
When the airlock for the trucks leading outside open there would be some lose of N2 and O2. How much of a surplus would be stored in tanks to make up for the lose?

Rebreathers could be at a slightly greater pressure than the ambient pressure. Keeps out dust and CO2 if there was not a tight seal. The rebreather keeps dust out of the lungs of the workers.

Any CO2 getting into the colony from the crew airlock would be in the prep area just before crew entered the airlock. That air would be sent to the garden section of the colony were the plants grown for food would convert the CO2 into O2. The air would first pass though a filter to remove any dust before heading to the garden area. Prep area would be for putting on overalls and work boots to help eliminate dust getting on clothes and getting into the colony.

Either way I see using small , medium, and large airlocks leading outside to reduce the energy needed and reduce the air lose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/14/2017 03:51 am
When the airlock for the trucks leading outside open there would be some lose of N2 and O2. How much of a surplus would be stored in tanks to make up for the lose?

By definition, even if if you don't draw down below Mars-pressure, you lose no more that 600 pascals times the volume of the airlock. So around 200g (7oz) per cubic metre of airlock.

[AIUI, ISS loses more air from leaky seals than it does from cycling the airlocks.]

You, otoh, are contaminating much more breathable air (~2kg/m³) every time someone moves between the main habitat and the work area. Which will happen a lot more often than cycling the main airlocks.

Rebreathers could be at a slightly greater pressure than the ambient pressure. Keeps out dust and CO2 if there was not a tight seal. The rebreather keeps dust out of the lungs of the workers.

Rebreathers are complex (http://rebreather.poseidon.com/wp-content/uploads/2014/12/rebreather_breakdown_3.jpg), uncomfortable, and have a fairly short duration. To get a proper seal around the nose usually means you go for either a full-face mask (http://www.advanceddivermagazine.com/articles/kija/diver6.jpg), or in-mouth (http://stuartscuba.com/wp-content/uploads/2016/09/rebreather.jpg). Overpressurising the rebreather means you are constantly leaking oxygen, reducing tank duration and increasing resource waste.

OTOH, in a normal atmosphere, dust exclusion just requires a simple dust-mask (http://modernsurvivalblog.com/wp-content/uploads/2013/02/dust-mask-n95-or-respirator.jpg), and ordinary maintenance work (http://www.shoemakerrigging.com/wp-content/uploads/2014/09/machine-maintenance.jpg) doesn't require anything (well, gloves, hardhat, hi-viz, whatever.)

You are turning working in the maintenance area into an activity as complex and dangerous as a deep-sea dive, nearly as complex as a full EVA.

Why?

It seems like you've picked a concept (CO₂ pressurisation) because you thought it would be easier/better than using breathable air. When people point out the difficulties, you "solve" the problems, but ignore that your concept is no longer "easy", it is incredibly complex and wasteful... and so now you're insisting on doing something in spite of it making things worse, just to keep the concept.

If feels like it should be easier to "just" pressurise Mars air, but when you drill down, it isn't. You aren't saving energy, you aren't saving time, but you are adding complexity, inconvenience, and risk.

That air would be sent to the garden section of the colony were the plants grown for food would convert the CO2 into O2.

Plants are actually more sensitive to CO₂ levels than humans. We can tolerate a few percent CO₂ for a short time, they can't.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/14/2017 04:13 am
Aside: On the ISS, the airlocks pump air back into the station when depressurising. There's no holding tanks or anything similar. (When re-pressurising, they simply open vents from the station again.) Simplicity is king.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/14/2017 07:05 am
Aside: On the ISS, the airlocks pump air back into the station when depressurising. There's no holding tanks or anything similar. (When re-pressurising, they simply open vents from the station again.) Simplicity is king.

Yes, but on the ISS there is no risk of contamination from the outside. On Mars this method would bring in contaminants, dust and CO2, into the habitat to deal with. That may or may not be acceptable.

Standard procedure IMO would be for vehicles to dock, no airlocks needed. Vehicles would go inside some pressurized volume for maintenance.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/14/2017 02:45 pm
Aside: On the ISS, the airlocks pump air back into the station when depressurising. There's no holding tanks or anything similar. (When re-pressurising, they simply open vents from the station again.) Simplicity is king.

Yes, but on the ISS there is no risk of contamination from the outside. On Mars this method would bring in contaminants, dust and CO2, into the habitat to deal with. That may or may not be acceptable.

Standard procedure IMO would be for vehicles to dock, no airlocks needed. Vehicles would go inside some pressurized volume for maintenance.
This suggests that as much as possible you might want vehicle systems to be inside pressure so they can be accessed while in the field without donning a suit...

Do we have a thread specifically for Martian vehicles? If so, some of Lamontagne's amazing renders ought to be crosslinked there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/14/2017 04:52 pm
Do we have a thread specifically for Martian vehicles? If so, some of Lamontagne's amazing renders ought to be crosslinked there.

We have this thread in the Mars section. It is about transport in general.

The best ways to get around Mars

http://forum.nasaspaceflight.com/index.php?topic=32636.msg1086383#msg1086383
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/14/2017 08:10 pm
Here is the BigAirlock.

It uses wheels and carbon fiber frames from Earth, as well as some aluminium rebar (rare!) but is mostly made from Martian concrete.  Since each door is 12m x 6x x 1.5m, they weigh about 150 tonnes on Earth, or about 50 tonnes on Mars.  All the wheels are driven by variable speed electrical motors, so they move fairly easily and quickly.  Actual seal is by an inflatable cushion between the frame and the doors.  The cushion is warmed electrically to maintain flexibility.
A second pivoting gate hides the gap from the base of the door to allow vehicles to cross.

These doors are inspired from the new Panama canal doors.
I think they should be pretty tough.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/14/2017 11:08 pm
I wasn't aware that the technology was this advanced:

http://www.businessinsider.com/rio-tinto-using-self-driving-trucks-to-transport-ore-2015-10

Which raises the question, if the trucks have no driver, do we still put the elements inside for maintenance?
I think yes for the rovers, perhaps not for the mining equipment.

Might enjoy seeing a full sized truck washing systems:
https://www.youtube.com/watch?v=aa7AfbRHxj0
https://www.youtube.com/watch?v=xaWoV5MgArc

Could this level of washing be enough to secure against perchlorates?  They are soluble, but stable in water.
And can be filtered out using reverse osmosis.

No more cab!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/14/2017 11:43 pm
Truck wash after the airlock.

So, what is missing from the colony?
And how many people would you fit into it?
Title: Re: Envisioning Amazing Martian Habitats
Post by: mikelepage on 01/15/2017 06:37 am
Truck wash after the airlock.

So, what is missing from the colony?
And how many people would you fit into it?

I'm not sure if you'd laid out elsewhere what specific purposes you imagined for all those chambers, or how much of this you envisaged being greens space/agriculture.  This is just my take from seeing your excellent pics in the previous posts.  Taking an ecosystem design approach to it, I think the answer to your question is probably "a lot less people than you're thinking." :) (That's assuming this is one of a kind, if there are many of these colony setups, then the need for redundancy is spread across them and you can support a more dense population in each).

Assuming this is the only one, (and I see how big those trucks are, so I can get an idea of the scale), then for true redundancy, I'd suggest 30 people or so.  I say that because there are 21 of those "cross-bar" chambers (each presumably with it's own backup ECLSS in case of emergency), and I'd suggest as many as 15 of them each of which would contain living quarters for two people, as well as the aquaponics rigs/algae bioreactors for which they have direct responsibility (I think it's likely that everyone will have to be personally responsible for at least some food cultivation and air production).  In future colonies one of these chambers might become the equivalent of the "family home" with children learning how to take care of food and air production in their own homes before taking on other responsibilities for the greater colony.

The remaining 6 cross-bar chambers would either be for processes that are more efficient when performed for the whole colony, or those that stink so much that no one would want to be in the same airspace as them.  Septic processing would probably be in duplicate for redundancy, and you'd also need a dedicated worm farm/invertebrate processing facility to take the output of the septic systems/food waste and turn them in the useful plant supplements.  I'd also suggest a chicken farming facility (meat and eggs), and a dedicated lab/medical area, and a communications centre/IT mainframe - which is also the logical place to put audio-visual recreational activities.

Getting back to the agriculture side of things, there's a decent level of separation between the chambers as set up, so you should have a decent chance to quarantine any new plant/fish diseases that emerge in the farmed crops, but I'd also suggest one of those big chambers at the end should be a botanical garden consisting entirely of biomass which is intentionally not cultivated for any specific agricultural reason, but a closed ecosystem where there is some capacity for undirected evolution to take place.  This gives you some fall-back just in case one of your staple crops gets wiped out by disease suddenly by a newly emergent disease (something to which monocultures are susceptible).  This is also where you would keep your reserve stocks of pollinators and other invertebrates.

The other two large chambers might be a mess-hall/kitchen/meeting place, and a physical recreational zone big enough for people to play team sports, play music and dance etc.

All the workshop areas would be closest to the main airlocks, I would think.  Anything intended to go outside, or from the outside would never enter any further into the colony than that group of 4 garages at the front, and it would basically be where you quarantine anything hazardous that your truck wash/cleaning systems can't filter out. 

That's my $0.02.  Great work on the visuals!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/15/2017 11:37 am
lamontagne, an element that might find its way into most amazing habitat-cities is underground large water cisterns, as water storage but also landscaped to enable swimming.

Since all life on earth is intimately tied to water, it may well turn out that views of waterscapes and the provision of swimming options will be desirable for psychological reasons.

The storage function of the cisterns would fill the need for massive buffers of water, securing the sources of  drinking water, water for agriculture, hydrogen for organic chemistry (plastics, methane, etc.), and a second source of breathing oxygen. A large body of water can also be used as a buffer to store and extract heat if necessary for smoothing out the thermal management of the colony.

The construction of the cisterns could be by the room and pillar method. Start from the ceiling and cut all the way down, shaping the pillars along the way. Entrance is near the ceiling and access for swimming is via a floating pontoon below the entrance.

The resulting room could look a lot like (or even be a replica) of the Byzantine cisterns of Constantinople / Istanbul. Borrowing from historic architectural and engineering marvels from all cultures on Earth would by itself help to make the habitats amazing and would also signal that on Mars, humanity is coming together as one in celebrating its common origins.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/15/2017 12:05 pm
Here is a view of the long garage.
Here is the BigAirlock.

Whenever I see your renderings of domes and cement constructions I cannot help but thinking "we don't need to create interior pressurized spaces on Mars. They're already there!" - Inside rocks and hills and behind cliff faces. We just need to carve them out.

Instead of bringing along the building materials for domes (which are very fragile anyway, and don't protect sufficiently against raditation) or learning how to make cement and constructing huge buildings... Instead of all that we just bring along a mature well-known enabling technology, tunnel digging, which makes it possible to basically create limitless interior space.

I wasn't aware that the technology was this advanced:
...
No more cab!

Exactly. No need for complicating the roadheader and haulage trucks by having a pressurized cab on them ("pressurized" since we already established, I believe, that we need equipment that works in a vacuum). I imagine that the operators can remotely control the vehicles, either just standing alongside, or in the case of tunnel digging, via remote cameras on the digger.

A huge advantage of dispensing with the cab is that the frontal cross-section of the roadheader can be drastically reduced. Some roadheaders already have a very long and low form factor. I am thinking that something like 2½ x 2½ meters (height and width) could be achieved in a still highly useful roadheader. With the usual pivoting drill head it should be able to make at least 4 meter tall tunnels.

A roadheader and haulage trucks of that size, assembled Ikea-furniture-style would make it reasonably straight-forward to unload the equipment from the IST. In the case of the road-header the drill-head, pivoting mechanism, electrical motor, wheels and chassis would fit easily out of the airlock and could be hoisted down with a simple hook-and-beam protruding from the IST hull, to be clicked-together on the Martian surface. More importantly, the assembled vehicles should be able to fit through reasonably sized air-lock doors (hoisted down to the Martian surface as well) that would be installed in the first rooms caved out of a nearby hill or cliff-face.

Since the first expedition primarily needs to set up a methane- and oxygen-production plant, there won't be much mass that can be dedicated to building the housing for all the equipment (and crew, if they don't stay on the IST).

We should not bring along the mass of which the habitats consist. We should bring along the equipment to build the habitats. As the old saying goes: "If people are hungry don't give them fish. Give them a fishing rod and teach them how to fish."

I think that the set-up sketched out here really is the best for the initial Mars settlement. It won't be pretty but it will be safe and functional and it will enable an almost limitless expansion potential. And yes, it will be amazing because it will be on Mars!

On Earth, Humanity started out in caves. Perhaps it will be the same on the Red Planet?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/15/2017 12:10 pm
Indeed, caves on Earth protected humanity when the environment became hostile during ice ages. Likewise, the man-made caves of Mars will protect humanity from the hostile environment there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/15/2017 01:05 pm
...
The construction of the cisterns could be by the room and pillar method. Start from the ceiling and cut all the way down, shaping the pillars along the way. Entrance is near the ceiling and access for swimming is via a floating pontoon below the entrance.

The resulting room could look a lot like (or even be a replica) of the Byzantine cisterns of Constantinople / Istanbul. Borrowing from historic architectural and engineering marvels from all cultures on Earth would by itself help to make the habitats amazing and would also signal that on Mars, humanity is coming together as one in celebrating its common origins.

Lumina, I definitely agree that the caves and tunnels on Mars will need to be constructed and furnished in a way that "exalts the human spirit", if you will. It probably won't happen in the very very first phase, but at some point the settlers should of course create a beautiful common space. Of course using the age-old techniques of domes, columns and arches.

Are you familiar with the "Temples of Humankind"? - A fascinating underground palace that for many years were kept secret. I imagine that some spaces in the first Martian city may look a bit like this...
The story: http://www.dailymail.co.uk/news/article-495538/Eighth-wonder-world-The-stunning-temples-secretly-carved-ground-paranormal-eccentric.html
Wikipedia: https://en.wikipedia.org/wiki/Temples_of_Humankind
Virtual tour: http://www.thetemples.org/tour/

Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 01/15/2017 01:48 pm
Physical paintings and ornamentation will be important, but I imagine there will also be video walls with images from the Mars surface, Earth, and Marvin the Martian cartoons, among other things.

For that matter, graffiti walls ( which could also be done with large touch screens).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/15/2017 02:44 pm
Mikilpage, wonderful and informative answer, thanks.  You guessed right, ecology has not been calculated yet.
I was hoping for about 400 people, but a bit less might be ok.  I can add volume and floor area as well.
The model is for the construction shack.  The actual colony would be the next stage.  So I would expect this to be non balanced, relatively hi density living, but with nice roomy living quarters.  Some meat would come from Earth at 140$ per kg, almost all minerals as well.  Nitrogen, oxygen, water, calcium would be local in situ production.
Toilets would be composting, and soil would be reserved for potted plants and decorative elements until the necessary bulk of soil had been built up, perhaps after a decade or so?
Hydroponics would provide beans and vegetables, and add roughage to the soil.  So a very artificial food production system, not very robust at all.  Still in a risky phase
How many people in such a case?

Title: Re: Envisioning Amazing Martian Habitats
Post by: mikelepage on 01/15/2017 05:13 pm
Mikilpage, wonderful and informative answer, thanks.  You guessed write, ecology has not been calculated yet.
I was hoping for about 400 people, but a bit less might be ok.  I can add volume and floor area as well.
The model is for the construction shack.  The actual colony would be the next stage.  So I would expect this to be non balanced, relatively hi density living, but with nice roomy living quarters.  Some meat would come from Earth at 140$ per kg, almost all minerals as well.  Nitrogen, oxygen, water, calcium would be local in situ production.
Toilets would be composting, and soil would be reserved for potted plants and decorative elements until the necessary bulk of soil had been built up, perhaps after a decade or so?
Hydroponics would provide beans and vegetables, and add roughage to the soil.  So a very artificial food production system, not very robust at all.  Still in a risky phase
How many people in such a case?

Hmmm so this is basically a construction crew you're talking about, coming in to do the initial digging/setup of your installation, most of whom see it as the adventure of a lifetime to spend 2 years or so to come do their part to build the colony, then go home to Earth again, and only a few of them actually mean to stay for good? 

With that initial phase, you've got heaps of space in your design, and the use of ITS as well: you can support as many people as you can ship food for - 100 per ITS iirc.  I'm just talking about sustainability in the long term...  That means having a stable, redundant ecosystem where the apex predator (us) doesn't need to consume more than a fraction of the total food output.  If something catastrophic happens on Earth or to the space program, you want your colony to be able to survive in isolation.

Once one installation is set up, the same process repeats nearby to build the next installation, and the next and the next, until your colony has a couple dozen such "towns".  It's a good idea for the colony to consist of many separate installations as an additional level of quarantine for the food crops.

Once you spread the redundancy by having many installations in the colony, then I reckon what you've created might support maybe 5x as many people as your initial 30... And 150 happens to be Dunbar's number, described as the rough limit to the number of people that any one person can maintain regular friendships with.  There's a bunch of social science that suggests it's a good number to organise around.
https://en.wikipedia.org/wiki/Dunbar's_number

A couple dozen installations of 150 gives you 3600 people, which is more than the 3000 individuals left (by one estimate) after the Toba super volcano eruption 75k years ago:
https://en.wikipedia.org/wiki/Toba_catastrophe_theory
The high estimate says there were 10,000 humans left after that catastrophe, so I'm thinking once the Mars colony gets to 10,000 people, we'll be pretty confident it's there for good.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/15/2017 06:00 pm
Only there for good if it is continuously sustained from Earth. 10,000 people would never be able to create the industrial base necessary for an independent Mars. They'd only survive as long as their Earth-produced equipment would last.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/15/2017 07:42 pm
"A computer modeled analysis of the feasibility of using Large Deployable Reflectors to redirecting solar radiation to the Martian surface (http://www.niac.usra.edu/files/students/final_report/2007/Woida_Rigel.pdf)." 

Proposes using orbiting convex mylar balloons to heat up a 1.5 km2 area of the surface. That might be a bit ambitious at first, but could a smaller scale version of this work on the ground? Maybe an array of mirrors positioned strategically around the side of a crater focused on a small greenhouse. The mirrors could be similar to mylar balloons, with an abrasion resistant sandbag like interior lining, and just filled with sand.

Edit: Maybe "sandbags" could also work as lightweight support for other external structures. For example, thin-film solar cells could simply be attached to one side of an angled sandbag, negating the need to bring relatively large and heavy frames.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/16/2017 12:08 am
"A computer modeled analysis of the feasibility of using Large Deployable Reflectors to redirecting solar radiation to the Martian surface (http://www.niac.usra.edu/files/students/final_report/2007/Woida_Rigel.pdf)." 

Proposes using orbiting convex mylar balloons to heat up a 1.5 km2 area of the surface. That might be a bit ambitious at first, but could a smaller scale version of this work on the ground? Maybe an array of mirrors positioned strategically around the side of a crater focused on a small greenhouse. The mirrors could be similar to mylar balloons, with an abrasion resistant sandbag like interior lining, and just filled with sand.

Edit: Maybe "sandbags" could also work as lightweight support for other external structures. For example, thin-film solar cells could simply be attached to one side of an angled sandbag, negating the need to bring relatively large and heavy frames.
Quite possibly; sandbags might find uses in the beginning of the colony.  I wonder how much the reflectors would cost compared to simply adding more solar collectors on the surface?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 01/16/2017 01:28 am
Re: Airlocks
When we have more than a few people passing in and out of a pressurized volume we may want double air locks. Airlock A would be at the indoor pressure, so people going out would crowd into A. Airlock B would be at outside near zero pressure so people entering would go into airlock B. When the doors were closed on both sides, airlock A would be depressurized by pumping air from A to B. When pressure in A was near zero the outside doors would open to let people out. When pressure in B reached interior pressure the interior doors would open to let people in. Next cycle would reverse direction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/16/2017 02:26 am
Re: Airlocks
When we have more than a few people passing in and out of a pressurized volume we may want double air locks. Airlock A would be at the indoor pressure, so people going out would crowd into A. Airlock B would be at outside near zero pressure so people entering would go into airlock B. When the doors were closed on both sides, airlock A would be depressurized by pumping air from A to B. When pressure in A was near zero the outside doors would open to let people out. When pressure in B reached interior pressure the interior doors would open to let people in. Next cycle would reverse direction.

IMO, anything with more than half a dozen people would want redundant airlocks.

However, I would have separate air-pump systems. To save cycling time, you want each airlock to be able to operate independently. (And you want to be able to dump air into or from either airlock to fast cycle them in an emergency.)

Likewise, I would have double airlocks on every section-isolation bulkhead within the habitat as well. If a section has a fast leak, and needed to be evacuated within a few minutes or tens of minutes, you don't want the first group reaching the airlock/barrier to have to wait (with air leaking from the rest of the habitat) until they are absolutely sure that the very last person is accounted for.

(We've all seen those classic race-the-clock scenes in generic SF movies where that one astronaut is left behind because he can't get through before the airlock door or emergency seal closes. In a better designed system, he would simply use the second airlock.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: mikelepage on 01/16/2017 04:56 am
Re: Airlocks
When we have more than a few people passing in and out of a pressurized volume we may want double air locks. Airlock A would be at the indoor pressure, so people going out would crowd into A. Airlock B would be at outside near zero pressure so people entering would go into airlock B. When the doors were closed on both sides, airlock A would be depressurized by pumping air from A to B. When pressure in A was near zero the outside doors would open to let people out. When pressure in B reached interior pressure the interior doors would open to let people in. Next cycle would reverse direction.

IMO, anything with more than half a dozen people would want redundant airlocks.

However, I would have separate air-pump systems. To save cycling time, you want each airlock to be able to operate independently. (And you want to be able to dump air into or from either airlock to fast cycle them in an emergency.)

Likewise, I would have double airlocks on every section-isolation bulkhead within the habitat as well. If a section has a fast leak, and needed to be evacuated within a few minutes or tens of minutes, you don't want the first group reaching the airlock/barrier to have to wait (with air leaking from the rest of the habitat) until they are absolutely sure that the very last person is accounted for.

(We've all seen those classic race-the-clock scenes in generic SF movies where that one astronaut is left behind because he can't get through before the airlock door or emergency seal closes. In a better designed system, he would simply use the second airlock.)

The term "double" airlock seems to be being used in two different senses here. 

I took Ionmars' comment to mean one travels from capsule A -> Airlock A -> Airlock B -> Capsule B
Reminded me of the double lock in Canal Saint Martin in Paris:

https://www.youtube.com/watch?v=VTKy_Q2SGtE

Whereas Paul451 seems to be referring to side-by-side locks like this one in Panama. 

https://www.youtube.com/watch?v=Iz2rb1xrckI

Both clearly have their advantages.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/16/2017 05:33 am
Mars space part(s), were the BFS lands and takes off. Delivers people and cargo. This is were the propellants would be made if there is water there or imported from other locations on Mars. Temporary living are tile moved to outpost.

From the space port(s) would be outposts, living , farming ( food production, cotton for cloths ) , mining , manufacturing. There would not just be one base with all the people in one place.

Were the CO2 is extracted from the Mars atmosphere ( for methane production ,BFS fuel ) is were the N2 and O2 would be extracted as well. The N2 and O2 would be used for breathing air in the different outposts. This would most likely be transported in liquid form in tanks on on trucks ( electric powered ). The ISS has it's air supply shipped and stored in tanks. https://www.nasa.gov/content/air-supply-high-pressure-tanks-ready-for-space-station

Airlocks and truck wash-

From the outside truck enters tunnel, door closes. ( This is to help reduce dust getting in , reducing CO2 entering , lose of N2/O2. )
Airlock door opens, truck enters. Door closes, airlock pressurizes.
Automated truck wash stars using recycled water ( pus soap and solvents ). Cleans of dirt , dust, oil , and grease.
Dirty water enters grate on floor of airlock and sent to recycler. Truck is blown dry and water collected below grate ( sucked in ) and sent to recycler.
Some CO2 would have entered in from the tunnel but filtered out during the truck wash blow dry cycle. Air exchanged with fresh air and the air that was in the airlock sent though an air processing unit.
Airlock door opens to garage and truck drives in and is sent to a work bay for service.
When trucks are exiting the airlock to outside air pressure is pumped from 14.7 PSI to a lower pressure .
Door opens to tunnel and truck enters tunnel. Tunnel air pressure is now greater than Mars ambient pressure for that location from the incoming higher air pressure from the airlock ( some N2/O2 and CO2 are mixed ).
Door closes, then a vacuum rated pump brings the air pressure closer to Mars ambient pressure from the location ( air is recycled for reuse with dust and CO2 removed ). Outer door is opened and truck drives out. Door is closed to keep dust out and more CO2 from entering and displacing the N2/O2 that is in the tunnel, till the next truck arrives to use the airlock.

So with this no need for my CO2 atmosphere in the garage area concept. Here is a link to the rebreather I had in mind ( from 1988, no longer in production ). This would have been modified for use for a longer period of time, but not longer than four hours.
http://www.therebreathersite.nl/Zuurstofrebreathers/Japan/eoba.htm
http://www.therebreathersite.nl/Zuurstofrebreathers/Japan/photos_eoba.htm
This still can be a good safety feature if someone gets stuck in an area were the life support fails or the air flow in not enough to remove the CO2 levels quick enough.

(This is a splinter topic from the IAC discussion thread which started with the below post:)
http://forum.nasaspaceflight.com/index.php?topic=41249.msg1597551#msg1597551

From what we have learned from IAC speech, we can probably safely assume that:

(a) ITS won't be carrying ready-made tuna can habitats to Mars (there is no pod-dropping)
(b) There is no need to carry ready-made habs (wedge, or any other shape) because the ITS itself can serve as a temporary hab on Mars
(c) Habitat components will be delivered flat-packed for assembly on Mars (like all other cargo)

These assumptions lead to the conclusion that the very first humans on Mars (on a long-stay mission) will be building habitats. Agree / disagree with this conclusion?

What kind of amazing, spacious habitats can we envision? What selection of habitat building components would you want in your flat-packed containers?
Starter base-
Inflatable habs connected by four side corner nodes with a top connector too. Add in suit ports and airlock for crew. Cover with Mars dirt , most of it but not the airlock and suit ports on the habs on the outer most points. The other exit would connect to the top of the nodes leading up past the dirt covering the habs and nodes. Any of these should be able by length to fit in the BFS and through the BFS cargo doors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/16/2017 07:12 pm
Quite possibly; sandbags might find uses in the beginning of the colony.  I wonder how much the reflectors would cost compared to simply adding more solar collectors on the surface?

Right, it would probably make more sense to just bring more solar cells instead of mirrors and use them to power additional lighting. Any excess power could be used for glass production, which could in turn be used for making mirrors.

Initial mars home. Pressurised cylinder contained within a rectangular cuboid (think shipping container) capable of supporting multiple tonnes of sandbags for radiation and micrometeorite shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 01/16/2017 08:00 pm
Re: Airlocks
When we have more than a few people passing in and out of a pressurized volume we may want double air locks. Airlock A would be at the indoor pressure, so people going out would crowd into A. Airlock B would be at outside near zero pressure so people entering would go into airlock B. When the doors were closed on both sides, airlock A would be depressurized by pumping air from A to B. When pressure in A was near zero the outside doors would open to let people out. When pressure in B reached interior pressure the interior doors would open to let people in. Next cycle would reverse direction.
There seems to be misunderstanding of this post. The aim is energy efficienc in operating the locks. Unlike Earth, inside air will be valuable because it has to be created from component parts of O2 and neutral gas like N2 created from other materials. So we would never depressurize by dumping the air outdoors. Likewise we would not pressurize with indoor air into the airlock because new air would have to be created to replace it.

So the idea was to reuse the same air by pumping it back and forth between two air locks, A conservation measure for expensive air.

A second advantage was that the air always flows from high pressure to low pressure so pumping is minimal, but no air going outdoors.

Edit: To further clarify - I am speaking of side-by-side airlocks. One is pressurized because people are coming indoors. The other is depressurized because people are going outdoors. Actually hadn't thought of the serial airlocks so these are some more good ideas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/16/2017 08:57 pm
You don't really need airlocks for people though, they're going to be pressurised at all times so can just enter and exit through their docked suits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/16/2017 10:05 pm
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Clearly designed for vehicles, not people.

I also incorporated other concepts I have in mind - the up-sloped/stepped design, the "central creek".

This all assumes of course that water is easy to come by, which I think is getting more certain by the day.

A different take on this. 1 Psi Mars atmosphere at one end, so still requires doors. Crates are used which fit snugly between the two doors to minimise atmospheric loss, especially when filled to the brim. Simply pump air back in from outside to maintain 1 Psi. Crates are attached to rails which transport them through the water. After submerging air is allowed time to find it's way out (crates have holes for releasing air, draining water, maybe the contents are in permeable sacks).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/16/2017 11:51 pm
Hi all, a flyover showing the Mars base.  There is a bit of decoration in the base after a few minutes of flying about  ;-)   I tried to give a sense of the scale of the thing. 
Remember that this is just the construction camp and mine site, the actual colony will be much larger.

https://www.youtube.com/watch?v=k-HTLz5iDGE

Everything is perfectible  :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/17/2017 09:00 am
Remember that this is just the construction camp and mine site, the actual colony will be much larger.

lamontagne, great work on the flyover, it really shows that you put a huge effort into this. I love the exciting camera "route" through the flame trench, inside rovers, etc.

As for the actual colony being much larger, well I don't quite agree there. I think your visualization shows the first settlement at a VERY advanced stage. So much construction, pads, vehicles, huge tunnels...

My vision for the initial settlement is much more limited, but yours is certainly inspirational.

You found a great 3D model of the crater to work with, but I don't see the first settlement being placed inside a crater. Too difficult to get out of.

Again, lovely vid, thx for your work!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/17/2017 09:52 am
Dao Angkan,

The wet-lock concept was discussed earlier in the thread.



So the idea was to reuse the same air by pumping it back and forth between two air locks, A conservation measure for expensive air.

You don't need serial airlocks for that. Side-by-side airlocks can also work on an alternating cycle (one up, one down). (There's really no advantage to serial airlocks.)

Either way, while you do halve the energy use compared to a system that actively pumps in both cycles, no airlock would work that way. They would always have one cycle where they merely match pressure by venting to/from a side with the target pressure, they only pump on the opposite cycle. (Ie, a breathable-air airlock would actively pump the air back into the habitat during the depressurisation cycle, but vent it back from the habitat during the re-pressurisation cycle. A pressurised-CO₂ airlock would actively pump Mars atmosphere up to hab-pressure during the pressurisation cycle, then vent it back to Mars during the depressuration cycle. Note, you only use energy on one cycle.)

So, IMO, you aren't really gaining anything. Instead your idea completely eliminates the redundancy, which is the whole point of having more than one airlock. During the pressurisation/depressurisation air-swap, both airlocks are sealed. Worse, being linked, if you need to do maintenance on one side (or you breach a seal on one side) both airlocks are out of commission.

A second advantage was that the air always flows from high pressure to low pressure so pumping is minimal

Think about the whole cycle. Half the cycle is always pumping from the low pressure airlock into the higher pressure airlock.

Likewise we would not pressurize with indoor air into the airlock because new air would have to be created to replace it.

No. During the depressurisation, you return the air to the habitat.

The volume of airlocks is trivial compared to the pressurised habitat, hence the pressure change from adding or removing one airlock's worth of air is less than the pressure change from ordinary thermal changes. As long as you pump the air back into the habitat during the depressurisation cycle, you aren't losing any air.

The only issue is that you are gaining one airlock's worth of 600pa CO₂ each pressurisation cycle. (And dust, which should be easily filtered.) If you are using the airlocks a lot, that will become an issue. It might be worth pumping the final 600pa down to vacuum each cycle before coming up to the target pressure.

(But that's a problem with your paired-locks as well.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2017 01:45 pm
Remember that this is just the construction camp and mine site, the actual colony will be much larger.

lamontagne, great work on the flyover, it really shows that you put a huge effort into this. I love the exciting camera "route" through the flame trench, inside rovers, etc.

As for the actual colony being much larger, well I don't quite agree there. I think your visualization shows the first settlement at a VERY advanced stage. So much construction, pads, vehicles, huge tunnels...

My vision for the initial settlement is much more limited, but yours is certainly inspirational.

You found a great 3D model of the crater to work with, but I don't see the first settlement being placed inside a crater. Too difficult to get out of.

Again, lovely vid, thx for your work!

Thanks!  I feel this is what would be required to enable the Musk 1 million people vision. Not necessarily reasonable in scope, of course.
The choice of a crater is questionable, but it does give a nice atmosphere :-)  The logic is that water resources and particularly large calcium carbonate resources may be buried fairly deep in the Martian crust, and this crater is in the bottom of a larger crater, so the excavation to reach the resources was 'free'. 

The design is pretty closely based on my own experience of participation in the Detour Gold mine site in Northern Canada.  when I first went there, we stayed is used trailers, about 20 people with an overflowing septic tank and a crowded cafeteria, surrounded by shacks with core samples inside.  The next time there, we doubled up in nice new trailers, we were about 100 and we were building the site for the construction camp, that was to hold 1200 people at maximum, all with individual rooms, flat screen TV's and fancy entertainment and sports center (this took less than a year to set up).  The construction site was a temporary installation to built the multi billion$ mineral crushing plant, garage for 350T trucks, offices and digging the pit, as well as the permanent housing for 400 workers.

Then the metals market collapsed and this whole installation was very nearly scrapped (from what I understand) but managed to squeak by with much lower profits than expected.  The life expectancy of the mine was a trade secret, but 15 years is a reasonable assumption.  After 15 years, the whole thing was to be demolished and the site returned to its original state of small spruce and firs, plus a nice, new, very deep lake.

Anyway, I was very impressed by the bootstrapping method I saw there, and I tried to replicate it in this design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 01/17/2017 02:10 pm
Hi all, a flyover showing the Mars base.  There is a bit of decoration in the base after a few minutes of flying about  ;-)   I tried to give a sense of the scale of the thing. 
Remember that this is just the construction camp and mine site, the actual colony will be much larger.

https://www.youtube.com/watch?v=k-HTLz5iDGE

Everything is perfectible  :-)

Great work. But: Did I miss the solar farm for power generation and the fuel plant?
Title: Re: Envisioning Amazing Martian Habitats
Post by: rpapo on 01/17/2017 02:27 pm
Great work. But: Did I miss the solar farm for power generation and the fuel plant?
Go ahead.  Ask for the moon.  Err, Mars...
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 01/17/2017 02:39 pm

Go ahead.  Ask for the moon.  Err, Mars...

Phobos or Deimos.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2017 03:16 pm
Hi all, a flyover showing the Mars base.  There is a bit of decoration in the base after a few minutes of flying about  ;-)   I tried to give a sense of the scale of the thing. 
Remember that this is just the construction camp and mine site, the actual colony will be much larger.

Everything is perfectible  :-)

Great work. But: Did I miss the solar farm for power generation and the fuel plant?
Yes, both.  I have no idea what the fuel plant might look like, so it's pending.  The solar farm was done in another earlier, larger design in this thread, and I wanted to link the two and haven't got around to it yet.  Perhaps I'll have a go at it over lunch....

If anybody else has other ideas about things to add, I'm willing ;-)   The flyover is programmed in now, so fairly easy to modify with added stuff.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 01/17/2017 04:39 pm
So the idea was to reuse the same air by pumping it back and forth between two air locks, A conservation measure for expensive air.

You don't need serial airlocks for that. Side-by-side airlocks can also work on an alternating cycle (one up, one down). (There's really no advantage to serial airlocks.)
Actually I haven't mentioned serial airlocks; I'm describing trying to describe side by side airlocks the same as you. But thanks for your reply. Edited.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/17/2017 08:52 pm
Only there for good if it is continuously sustained from Earth. 10,000 people would never be able to create the industrial base necessary for an independent Mars. They'd only survive as long as their Earth-produced equipment would last.

That's an excellent point, and while it's off topic, but I will point out that trade allows countries to create value within their borders to obtain resources and luxuries they do not have already in order to sustain themselves.

As long as the martians have something of value to trade, there is no reason to think they can't be self-sustaining through trade- as is the norm with every nation on Earth.

Due to the prohibitive distance I actually think that what a Mars colony will have to trade will largely be immaterial goods. I am thinking documentaries, low-gravity sports events, feature movies and - of course - reality TV! - Believe me, it'll be yuuuge!

I'm actually serious here. The process of colonization will capture the attention of a large portion of humanity. If it can be beamed down it can be sold and I'm sure TV, VR etc will play a huge role in the Martian economy. Itwill be a great example of a "knowledge economy" and the earning potential of entertainment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/17/2017 11:07 pm
Maybe the biggest physical export could be meteorites, some are quite valuable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/18/2017 04:49 am
So the idea was to reuse the same air by pumping it back and forth between two air locks, A conservation measure for expensive air.

You don't need serial airlocks for that. Side-by-side airlocks can also work on an alternating cycle (one up, one down). (There's really no advantage to serial airlocks.)
Actually I haven't mentioned serial airlocks; I'm describing trying to describe side by side airlocks the same as you. But thanks for your reply. Edited.
I was thinking of something similar. A cylinder next to the airlock of greater volume. Use a vacuum pump to transfer the airlock air to the cylinder. However have a piston in the cylinder to send the air back to the airlock.

1 ) valve opens sending air into cylinder as piston pulls back increasing the volume in the cylinder.
2 ) once the piston is pulled back as far as it can the valve is closed
3 ) the vacuum pump start and removes most of the remaining air in the airlock and placing it into the cylinder
4 ) airlock opens and truck or other item heads out to Mars outdoors
5 ) another truck or item enters airlock, airlock door closes
6 ) valve to cylinder opens and piston pushes forwards sending the air back into the airlock removing all the air in the cylinder
7 ) valve is shut
8 ) air is added to bring the pressure up to the air pressure of the next chamber ( garage or other area that the airlock might be attached to )
9 ) airlock door opens and item enters garage
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/18/2017 05:10 am
Try using MS Paint to illustrate your idea. Or equivalent.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/18/2017 07:40 am
I was thinking of something similar. A cylinder next to the airlock of greater volume. Use a vacuum pump to transfer the airlock air to the cylinder. However have a piston in the cylinder to send the air back to the airlock.

The piston is just a pump. The energy required for the piston to push the air out of the chamber is the same as using a fixed-volume air tank and a normal sized vacuum pump.

(If I'm reading your suggestion correctly.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/19/2017 12:36 am
Big and small colonies merged.  The white rectangles are solar panel arrays.  Each array is 200m x 200m.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/19/2017 03:12 am
I was thinking of something similar. A cylinder next to the airlock of greater volume. Use a vacuum pump to transfer the airlock air to the cylinder. However have a piston in the cylinder to send the air back to the airlock.

The piston is just a pump. The energy required for the piston to push the air out of the chamber is the same as using a fixed-volume air tank and a normal sized vacuum pump.

(If I'm reading your suggestion correctly.)
It is an idea, but would need to be analyzed. Might need several cylinders each with a piston.

Cylinder one take the airlock from 14.7 PSI down to 7.35. And each one following take the pressure down half again,
The fifth cylinder would bring it down to .459375 PSI ( still much higher than the outside air pressure ).
This is all done by pulling up on a piston increasing the volume in each cylinder
To return the air to the airlock the piston in each cylinder would need to lower decreasing the volume in each cylinder increasing the pressure in the cylinder to just above the air pressure in the airlock pushing the air into the airlock.
Some air would need to be added that was lost when the airlock was opened to the outside.

The idea from the other poster of two airlocks side by side would have air from on at 14.7 PSI go into the other at near vacuum. That would bring the two airlocks to 7.35 PSI when a valve is opened between the two. The rest of the transfer of air would ned to be down by vacuum pump. As not all the air can be transfered some air will need to be added in from a tank and what was lost when the airlock door was open to the outside.

By cylinder and piston could be a big problem. The compressor and vacuum pump with an air tank would seem to be the simplest way to go.

What uses less power per given mass of air moved?
A vacuum pump or a compressor running between 5 PSI and 15 PSI?
Is it the most energy intense when the airlock is drawn near to vacuum
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/19/2017 05:01 am
Seems overcomplicated.

Lamontagne, nice work on the vids....
Title: Re: Envisioning Amazing Martian Habitats
Post by: mikelepage on 01/19/2017 06:24 am
So the idea was to reuse the same air by pumping it back and forth between two air locks, A conservation measure for expensive air.

You don't need serial airlocks for that. Side-by-side airlocks can also work on an alternating cycle (one up, one down). (There's really no advantage to serial airlocks.)
Actually I haven't mentioned serial airlocks; I'm describing trying to describe side by side airlocks the same as you. But thanks for your reply. Edited.

My mistake guys.  I ended up muddying the waters in the attempt to provide clarification.

FWIW there is an advantage to serial locks in high throughput situations because even though each person in transit spends the same amount of time transitioning from pressure A to pressure B, the total throughput can be higher, because the cycle time for each lock is smaller.

e.g. Suppose the total pressure change required is x, and the time needed for an airlock to go through a full cycle (A->B->A) is y.  If each serial lock only need change through 0.5x, then the time needed for each airlock to go through a full cycle is 0.5y, resulting in a twofold increase of throughput.  It's only efficient if the traffic is moving in one direction though (e.g. lots of people going outside in the morning and coming back in the evening), so if your choice is between side-by-side and serial, then you'll go side-by-side.

The most efficient setup would be side-by-side serial locks, with an "in" direction and an "out" direction.  Obviously somewhat further in the future, but this is effectively the same problem as escalators vs elevators - only in high traffic areas is it worth using escalators.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/19/2017 10:18 am
I may be totally wrong but those concepts seem overly complex. What I would think suitable would be a sufficiently large volume to store air in while the airlock is evacuated. Large enough, that the pressure does not get too high, making the pumps work harder. That way, if there are two airlocks, they would operate independently. Failure of one would not affect the other. The machinery of an airlock, pumps and doors may be complex and expensive. Some extra volume carved out of the rock is not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/19/2017 10:42 am
I was thinking of something similar. A cylinder next to the airlock of greater volume. Use a vacuum pump to transfer the airlock air to the cylinder. However have a piston in the cylinder to send the air back to the airlock.
The piston is just a pump. The energy required for the piston to push the air out of the chamber is the same as using a fixed-volume air tank and a normal sized vacuum pump.
Might need several cylinders each with a piston.
Cylinder one take the airlock from 14.7 PSI down to 7.35. And each one following take the pressure down half again,
The fifth cylinder would bring it down to .459375 PSI ( still much higher than the outside air pressure ). [...etc]

The energy required for the sequence is the same as the energy required for a single step.

This is conservation-of-energy stuff. You can't reduce the overall energy consumption of a process by breaking it into smaller steps.



I may be totally wrong but those concepts seem overly complex. What I would think suitable would be a sufficiently large volume to store air in while the airlock is evacuated. Large enough, that the pressure does not get too high, making the pumps work harder.

Hmmm, with a large space like that, full of breathable air, people could use it as some kind of living area...

...you know, like a habitat.

During the depressurisation, you return the air to the habitat.
The volume of airlocks is trivial compared to the pressurised habitat, hence the pressure change from adding or removing one airlock's worth of air is less than the pressure change from ordinary thermal changes. As long as you pump the air back into the habitat during the depressurisation cycle, you aren't losing any air.
8)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/19/2017 12:04 pm
Only there for good if it is continuously sustained from Earth. 10,000 people would never be able to create the industrial base necessary for an independent Mars. They'd only survive as long as their Earth-produced equipment would last.

That's an excellent point, and while it's off topic, but I will point out that trade allows countries to create value within their borders to obtain resources and luxuries they do not have already in order to sustain themselves.

As long as the martians have something of value to trade, there is no reason to think they can't be self-sustaining through trade- as is the norm with every nation on Earth.

Actually, countries can -and do!- sustain a negative trade balance (imports exceed exports) for as long as they can sustain a positive capital account balance (investment inflows from other countries exceed outflows). Once Mars gets going, complete with IPO's etc., Mars will have a strongly positive capital account balance, so Mars can grow economically without having to ship anything back to Earth. It will be smart to use that capital to become self sustaining while investor appetite lasts.

Since property development is the favorite toy of speculators on Earth, amazing Martian cities will probably be key in whipping up investor demand for "Mars plays". So as we keep envisioning amazing Martian habitats we may in fact be bringing the future a little closer :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/19/2017 03:38 pm
(There's really no advantage to serial airlocks.)
FWIW there is an advantage to serial locks in high throughput situations because even though each person in transit spends the same amount of time transitioning from pressure A to pressure B, the total throughput can be higher, because the cycle time for each lock is smaller.

How are you getting a higher throughput from two locks in series than two locks in parallel?

(See attached sketch for what I mean. Hopefully it's not too confusing. Blue is pressurised, half-blue represents half-pressure. The time to cycle through four groups is the same for serial and parallel.)

Also side-by-side gives you immediate redundancy, which is worth more than speed anyway.

It's only efficient if the traffic is moving in one direction though

No, it works both ways, even for the serial cycling airlocks. The guys coming in simply swap positions with the guys going out. (I haven't shown it in my sketch, but you can imagine four more EVA crew(s) passing the other way at the same time.)



Aside, for Lamontagne and other modellers:

People suggest unpressurised garages, and you usually depict these as stand-alone structures.

However, when you look at the ISS "Quest" airlock, there's an unpressurised extension from the airlock-proper which they use to prep tools and equipment for work. On ISS, I suspect it's mainly to reduce the risk of tools and parts drifting away. There's an umbilical connection to extend PLSS-lifetime.

But I think that on Mars, it also makes sense to have the unpressurised work areas extending directly out from the airlock. I don't think any airlock will open directly onto the Mars surface. Similarly makes sense to have a prep-area inside that's semi-isolated from the habitat.

So any airlock on a Mars habitat (whether for crew or entire vehicles) will include two non-pressure-changing chambers, one inside at habitat pressure, one outside at Mars pressure. (As shown in one of my crude sketches.)

I think the same will be true even of suit-locks and vehicle docking-ports. They will be inside closable, but unpressurised, "sheds" attached to the airlock. This helps with dust exclusion, reduces sun damage, and should reduce thermal cycling a little.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/19/2017 05:20 pm


Aside, for Lamontagne and other modellers:

People suggest unpressurised garages, and you usually depict these as stand-alone structures.

However, when you look at the ISS "Quest" airlock, there's an unpressurised extension from the airlock-proper which they use to prep tools and equipment for work. On ISS, I suspect it's mainly to reduce the risk of tools and parts drifting away. There's an umbilical connection to extend PLSS-lifetime.

But I think that on Mars, it also makes sense to have the unpressurised work areas extending directly out from the airlock. I don't think any airlock will open directly onto the Mars surface. Similarly makes sense to have a prep-area inside that's semi-isolated from the habitat.

So any airlock on a Mars habitat (whether for crew or entire vehicles) will include two non-pressure-changing chambers, one inside at habitat pressure, one outside at Mars pressure. (As shown in one of my crude sketches.)

I think the same will be true even of suit-locks and vehicle docking-ports. They will be inside closable, but unpressurised, "sheds" attached to the airlock. This helps with dust exclusion, reduces sun damage, and should reduce thermal cycling a little.

Makes sense.  I'll add something of the sort to my model.  Any thoughts on what a fuel production facility might look like?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/19/2017 06:03 pm
Any thoughts on what a fuel production facility might look like?

(https://komexei.eu/sites/default/files/What-we-do-Operations.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/19/2017 06:06 pm
Unlikely like that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/19/2017 07:40 pm
Unlikely like that.
Agree.

First, ISRU production itself seems fairly simple, not nearly that many different components, no?

Second, I would think you'd want to minimize clambering about, and presumably horizontal space is not at a premium, so even if you still have fractional distillation towers (that's not really for fuel PRODUCTION, but rather something you might see in downstream chemical works that use methane feedstock) you would want most of the rest spread around horizontally for ease of maintenance.

Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/19/2017 09:04 pm
I may be totally wrong but those concepts seem overly complex. What I would think suitable would be a sufficiently large volume to store air in while the airlock is evacuated. Large enough, that the pressure does not get too high, making the pumps work harder.

Hmmm, with a large space like that, full of breathable air, people could use it as some kind of living area...

...you know, like a habitat.

Not fun to live there with the changing pressure. But the area could house the pumps and filters. Constant pressure during maintenance.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/19/2017 09:14 pm
T'was meant to be funny. {Shrug}

In seriousness, it was an ammonia production plant. Haber-Bosch is analogous to Sabatier or Fischer-Tropsch, so the complexity isn't far off. The scale is, of course. IIRC, the image I grabbed was from a 1m tonne/yr production facility. About a hundred-fold more than needed for, say, ten ITS/BFS per synod.



ISS's Sabatier.

(https://www.nasaspaceflight.com/wp-content/uploads/2013/10/Z72.jpg)



Lamontagne,

The core of the ISRU plant will likely be contained in a single pod, however large can be installed in a cargo-ITS and unloaded in one piece. Which will probably just look like a tank. Surrounded by actual tanks of various sizes, from pressurised CO₂ to water to two years worth (about 2000 tonnes per ship) of propellant production, plus plumbing and pumps. Plus extra processing systems and storage for whatever else you want from Mars' atmosphere, nitrogen, argon, etc. Plus heat-exchanges and huge radiators for the liquification plants. Plus the actual propellant transfer systems (you aren't going to land next to prop tanks.)

For a long time, upgrading for the larger colony would simply be more plants, not a single larger plant. Due to commonality of processes and parts.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/19/2017 09:21 pm
Not fun to live there with the changing pressure.

If the airlock is 1% of the volume of the habitat, the pressure difference is the equivalent of a 3℃ temperature variation. And much less than you'd typically experience on Earth when a cold front passes your neighbourhood. Or climbing a 90 metre hill on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/19/2017 10:02 pm
For a long time, upgrading for the larger colony would simply be more plants, not a single larger plant. Due to commonality of processes and parts.
And adding redundancy... losing one plant doesn't mean losing all production...
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/19/2017 10:19 pm
Not fun to live there with the changing pressure.

If the airlock is 1% of the volume of the habitat, the pressure difference is the equivalent of a 3℃ temperature variation. And much less than you'd typically experience on Earth when a cold front passes your neighbourhood. Or climbing a 90 metre hill on Earth.

I think you are implying pumping the air into the main habitat. Maybe but I am not sure this is a good idea. It may be more difficult to keep pollutants out than when pumping it into a reservoir volume.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/19/2017 11:06 pm
Not fun to live there with the changing pressure.

If the airlock is 1% of the volume of the habitat, the pressure difference is the equivalent of a 3℃ temperature variation. And much less than you'd typically experience on Earth when a cold front passes your neighbourhood. Or climbing a 90 metre hill on Earth.

I think you are implying pumping the air into the main habitat. Maybe but I am not sure this is a good idea. It may be more difficult to keep pollutants out than when pumping it into a reservoir volume.
If the hab area is only 10 times the volume of the airlock that could bring the pressure from 14.7 to 16.7 PSI by removing air from the airlock to the hab area. That could cause health issues. Increase in CO2 level from outside air and dust is another issue.

Could use  serial and parallel airlocks.
Person or equipment enters airlock A, close door and open valve to B. When the pressure are both the same close the valve and then open door to B.  Enter B and close door. Option, open a valve and turn on vacuum pump sending air to one of the other airlocks or if someone or equipment is entering from outside in C the could open valve to C. When pressure is equal in both turn on vacuum pump to remove most of the air in B to C and then close valve and turn off pump. Open the door in C to the outside and person walks out and door is shut. If some one is in C the a valve is opened to  other airlock or air tank increasing pressure in C till it is equal to D, valve is closed. Door from C to D is opened and person enters D, door is closed. Air is added to D ( from other airlock or air tank ) till it reaches the habs pressure. Door from D to hab is opened and crew enters hab ( EVA prep area ).

Air pressure in A and D should never be below half the habs pressure. B and C should never be above half the habs pressure. So three holding tanks are needed. One for A and D , another for B and C, and the third on to hold air to resupply what was lost to the outside from B and C.

When opening a valve between A and B for crew to exit the only energy needed is for opening and closing the valve. The air will flow from high pressure to low pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/19/2017 11:17 pm
14.7psi is unlikely to be the internal pressure of Mars habs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/19/2017 11:19 pm
14.7psi is unlikely to be the internal pressure of Mars habs.
What would be and why?

Edit:
14.7 PSI is very close to Earth sea level. So that is what i used for the example. Let the Mars colony engineers deal with what pressure would be if there ever is a colony. So the pressure I used was just for the example.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/19/2017 11:34 pm
I think you are implying pumping the air into the main habitat.

I thought I'd stated it outright several times.

Maybe but I am not sure this is a good idea. It may be more difficult to keep pollutants out than when pumping it into a reservoir volume.

The first section inside the hab, past the airlock, will have the suits, vehicles, equipment being torn down and rebuild, fluids being purged and exchanged, lubricants applied to joints, cutters, welders, etc etc. And dust, of course.

You are going to be scrubbing the air. The airlock adds almost nothing to it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rpapo on 01/19/2017 11:35 pm
14.7psi is unlikely to be the internal pressure of Mars habs.
What would be and why?
Why not 14.7?  Why that precise value?  That pressure does not equalize to anything on Mars.

What pressure?  Something less, but not too much less.  This human has no problem living at 8000ft, which is roughly 11psi.  On the other hand, at 16000ft, roughly 8psi, I have difficulty doing much besides sit around.

You can use a lower pressure if you increase the partial pressure of oxygen, but we have seen from Apollo 1 that that is not necessarily a good idea.

UPDATE: I gather this topic is a dead horse whose beating I did not witness.  If such is the case, let's leave the poor thing lie.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/19/2017 11:35 pm
14.7psi is unlikely to be the internal pressure of Mars habs.
What would be and why?

Let's not start this again.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Johnnyhinbos on 01/20/2017 12:10 am
14.7psi is unlikely to be the internal pressure of Mars habs.
What would be and why?
Why not 14.7?  Why that precise value?  That pressure does not equalize to anything on Mars.

What pressure?  Something less, but not too much less.  This human has no problem living at 8000ft, which is roughly 11psi.  On the other hand, at 16000ft, roughly 8psi, I have difficulty doing much besides sit around.

You can use a lower pressure if you increase the partial pressure of oxygen, but we have seen from Apollo 1 that that is not necessarily a good idea.
That's not correct. (Though I also agree that this has been discussed far too much already in other threads).

No need to increase PP O2. Just remove more of the inert. Why would you want to fill your atmosphere with that much inert gas? Where would you get this gas from?  Import Nitrogen?  Argon? (That's a nice fat molecule that us tech divers like to fill drysuits with when breathing helium mixes). Keep PP O2 the same and keep the hab at 4PSI with a higher O2 % but still low PP O2. This eases lock in/out pressure delta and reduces EVA prebreathe
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 12:47 am
It's my fault, but... you can get argon and nitrogen form Mars' atmosphere just fine. And the reason to reduce oxygen partial pressure is that:
1) humans adapt just fine to lower oxygen level
2) fire risk increases if you remove buffer gas. Not a lot, mind you (provided you keep oxygen partial pressure at no more than sea level), but still some. So it makes sense to reduce oxygen partial pressure a bit (to reduce fire risk) as you remove buffer gas.

Anyway. I just don't see exactly 14.7psi as making sense. Only people living very close to 0 altitude experience that on Earth. I'd guess somewhere between 4 and 12.5psi.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 01/20/2017 01:08 am
...You can use a lower pressure if you increase the partial pressure of oxygen, but we have seen from Apollo 1 that that is not necessarily a good idea.
...
Apollo 1 had a O2 partial pressure of 15 psi, some 5 times that at sea level and about 10 times what people can typically adapt to.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/20/2017 02:30 am
Another point in favor of using denser atmospheres is heat transfer.  Lower density air has less heat capacity, so heat transfer is not as good.  Perhaps not so serious in a highly controlled environment as the ISS, shuttle and such, but might make life a bit more complicated overtime. Would need to double ventilation rates, for example, in systems that use air as the heat transfer fluid.

I think we should design to be capable for normal atmospheric pressure, and the operators will adjust to what is best when the time comes.  A bit of overdesign in a colony is a good thing, IMHO.
Some plants/soils probably need atmospheric nitrogen, I expect.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/20/2017 02:39 am
In the expected operation of the Mars colony envisioned by Elon Musk, do the ships always stay on Mars for 2 years or are there possibilities of a quick turnover?
If the turnover is 2 years, then we will never need tanks, or at least not much more than small production tanks, as the ITS spaceships will be available to serve for storage.

If the turnover is rapid, then the ships need to be fueled and we need tanks.  Any input on this would greatly help on fixing a design for the production plant.

The electrolysis seems like a fairly efficient process these days, and the Sabatier reaction, although it takes place at high temperature, may not be very exothermic?  Will we need a lot of cooling?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/20/2017 03:21 am
Another point in favor of using denser atmospheres is heat transfer.  Lower density air has less heat capacity, so heat transfer is not as good.  Perhaps not so serious in a highly controlled environment as the ISS, shuttle and such, but might make life a bit more complicated overtime. Would need to double ventilation rates, for example, in systems that use air as the heat transfer fluid.

I think we should design to be capable for normal atmospheric pressure, and the operators will adjust to what is best when the time comes.  A bit of overdesign in a colony is a good thing, IMHO.
Some plants/soils probably need atmospheric nitrogen, I expect.

I agree, especially for settlements consisting mostly of excavated tunnels. When you don't have to build the pressure vessel, the justification for lower than normal pressure mostly disappears.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 04:37 am
Another point in favor of using denser atmospheres is heat transfer.  Lower density air has less heat capacity, so heat transfer is not as good.  Perhaps not so serious in a highly controlled environment as the ISS, shuttle and such, but might make life a bit more complicated overtime. Would need to double ventilation rates, for example, in systems that use air as the heat transfer fluid.

I think we should design to be capable for normal atmospheric pressure, and the operators will adjust to what is best when the time comes.  A bit of overdesign in a colony is a good thing, IMHO.
Some plants/soils probably need atmospheric nitrogen, I expect.
"Normal atmospheric pressure" could be 10-12psi depending on where you live. Enough with the prejudices of the flat landers!

Remember, "over designing" goes both ways. By operating at lower pressure, your structures now have that much more margin...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Nomadd on 01/20/2017 05:08 am
 Few people seem to have any difficulty in Cusco after a couple of days at 9.5 psi.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 07:30 am
2) fire risk increases if you remove buffer gas. Not a lot, mind you (provided you keep oxygen partial pressure at no more than sea level),

Once again, that's the opposite of how it works.

If you keep the percentage of oxygen in the air constant, then lowering the overall pressure has only a small effect on flammability and ignition risk.

If you keep the partial pressure of oxygen constant, then flammability varies strongly with changes in overall pressure.

It's confusing because biology is mainly affected by partial pressures.

(Also the type of buffer gas matters for flammability. AIUI, argon is much less effective as a buffer gas. Argon/o₂ is the same as nitrogen with higher percentage O₂. By using argon, you are wasting higher pressure.)

[edit: 10-12 psi with 2.2-2.5 psi oxygen pp seems reasonable, although I'd prefer higher pressure with lower O₂ PP to give 15% oxygen. (Whereas 7 psi is not an option, outside of specially build fire-proofed areas like airlocks.) But there's still no reason to jump on people every single time they say "15psi" (or 14.7), unless a 20% pressure difference somehow completely refutes their point.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 08:07 am
If the airlock is 1% of the volume of the habitat, the pressure difference is the equivalent of climbing a 90 metre hill on Earth.
If the hab area is only 10 times the volume of the airlock that could bring the pressure from 14.7 to 16.7 PSI by removing air from the airlock to the hab area. That could cause health issues.

A 13% variation in pressure is the equivalent of driving 1km uphill on Earth. You probably need to pop your ears. That's it.

However, if we are talking about a colony or settlement, and not a NASA mission, then we have to assume they are growing food to support themselves. Therefore the volume of space required per-person is much larger than, for example, the size of the ISS. And the ISS cycles air from the airlocks back into the rest of the station.

Increase in CO2 level from outside air and dust is another issue.

This applies to separate tanks as well. Unless you draw down to vacuum, each cycle adds a small amount of CO₂ to the pressurisation gas. At some point you have to filter or replace it.

As for dust, the room just inside from the airlocks is where everything from the surface of Mars is taken. Suits/vehicles, parts and tools, etc. It's going to collect dust. You will have extra air filters in that room.

Could use  serial and parallel airlocks. [four airlocks described]

I obviously wasn't clear enough. Dividing the airlock into multiple airlocks doesn't change the energy required.

The work required to pressurise a volume is the same as the work required to lift an equivalent weight. (Remember, that's how we measured air pressure, in a glass tube filled with fluid which is physically lifted by that air pressure. The back-pressure on a pump is the same as a weight pushing down on a jack.)

And like lifting a weight, it doesn't matter if you divide the object into four parts, or ten, the total energy will remain the same.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 08:29 am
In the expected operation of the Mars colony envisioned by Elon Musk, do the ships always stay on Mars for 2 years or are there possibilities of a quick turnover?
If the turnover is 2 years, then we will never need tanks, or at least not much more than small production tanks, as the ITS spaceships will be available to serve for storage.
If the turnover is rapid, then the ships need to be fueled and we need tanks.  Any input on this would greatly help on fixing a design for the production plant.

That was my reasoning, but I was under the impression that Musk's comments about ITS had pretty much ruled out the idea that the ships stay on Mars for the entire time between synods. So I ignored that case. (I just had a quick search around, but I can't find a specific quote.)

If Musk's intention is fast-turnaround and relaunch, then you need storage for around 2000 tonnes of propellant per ship. So if you assume ten ships in the early colony, you need storage for 20,000 tonnes of liquid propellant. Plus all the plumbing to return the boil-off back to the liquification plant.

Alternatively you need a production plant and power systems that's an order of magnitude larger, in order to produce most of the propellant while the ships are on Mars. That seems extraordinarily wasteful.

Will we need a lot of cooling?

I was thinking about the liquification plant for the liquid propellant. Presumably you'll use a heat-exchange to recover as much heat back into the reactor-side, but you will still need a lot of radiators to dump the heat extracted from liquifying thousands of tonnes of gas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Johnnyhinbos on 01/20/2017 08:46 am
Few people seem to have any difficulty in Cusco after a couple of days at 9.5 psi.

Ugh, unless you're me in 1987 after too many pisco sours in Lima the night before. Arriving in 10,000 foot  Cusco was, er, unpleasant. Though I will say just a day later found me mountain biking to Machu Picchu, so it is amazing how the human body recovers.

2) fire risk increases if you remove buffer gas. Not a lot, mind you (provided you keep oxygen partial pressure at no more than sea level),

Once again, that's the opposite of how it works.

If you keep the percentage of oxygen in the air constant, then lowering the overall pressure has only a small effect on flammability and ignition risk.

If you keep the partial pressure of oxygen constant, then flammability varies strongly with changes in overall pressure.

It's confusing because biology is mainly affected by partial pressures.

(Also the type of buffer gas matters for flammability. AIUI, argon is much less effective as a buffer gas. Argon/o₂ is the same as nitrogen with higher percentage O₂. By using argon, you are wasting higher pressure.)

[edit: 10-12 psi with 2.2-2.5 psi oxygen pp seems reasonable, although I'd prefer higher pressure with lower O₂ PP to give 15% oxygen. (Whereas 7 psi is not an option, outside of specially build fire-proofed areas like airlocks.) But there's still no reason to jump on people every single time they say "15psi" (or 14.7), unless a 20% pressure difference somehow completely refutes their point.]
Yes, it's important folks think in terms of partial pressures and not percentages. As I mentioned upthread there's a lot to be gained from reducing the overall pressure while maintaining (or near to) the PP O2.

The makeup gas(s) used to backfill the remaining pressure required is an interesting challenge. Humans need at minimum 0.16 Atmospheres Absolute (ATA) PP O2. Air at 1 ATA (ie sea level) contains 0.21 ATA PP O2.

Mars atmosphere is right around 0.0059 ATA. Pretty close to a vacuum for all intents and purposes. Therefore we'd want to design the LSS of the hab with the absolute minimum pressure we can in order to reduce the pressure delta between Mars atmosphere (outside) and hab atmosphere (inside).

10 psi for the hab is a good starting point, though perhaps it could iterate down to a lower pressure.
That's 0.68 ATA. Of that we'll use 0.21 ATA for oxygen. You don't want to go much lower because it's more healthy for us mammals when we're not hypoxic. And you definitely don't want to go much higher because higher PP O2 can lead to pulmonary toxicity over time.

So we have to backfill our breathing gas with "something". In the world of rebreather diving this something is called diluent. Diluent can be any non-metabolized gas mixture - inert.

Dalton's law says we can simply add up the partial pressures of the constituent gasses to get the total pressure. We have 0.47 ATA to play with.

Let's start with CO2. Plants like it, we don't. Let's not mess around with it. We'll maintain it at what's in air. 0.004 ATA. So we need to come up with 0.466 ATA.

It's a good point about nitrogen with regards to plants and it's also a good point about the thermal benefit of higher densities, but higher densities, as mentioned, is a problem for transition to Mars atmosphere (or for transitioning to a suit designed to operate in the Martian atmosphere). I had mentioned argon upthread because argon is an excellent insulator, it has much lower thermoconductivity than nitrogen. If both gasses can be extracted from the CO2 rich atmosphere then perhaps we should look at a 50/50 split. Reason being is perhaps a bit too off topic for this thread, but when going to an EVA suit that operates at around 4 psi of pure O2 you need to worry about isobaric counterdiffusion and argon is more forgiving than nitrogen in that respect. Argon is more narcotic at higher pressures, but we are never leaving with pressures > 1ATA regardless, so that's a non issue.

So in conclusion I'd suggest designing the LSS to operate at 10psi, or 0.68 ATA, with 0.21 ATA oxygen, 0.23 ATA nitrogen, 0.23 ATA argon, and allow 0.004 ATA carbon dioxide.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 10:30 am
If you keep the percentage of oxygen in the air constant, then lowering the overall pressure has only a small effect on flammability and ignition risk.
If you keep the partial pressure of oxygen constant, then flammability varies strongly with changes in overall pressure.
Yes, it's important folks think in terms of partial pressures and not percentages.

{laughs} That's the opposite of what I said.

When it comes to fire risk, you really have to pay attention to percentages. Hence...

As I mentioned upthread there's a lot to be gained from reducing the overall pressure while maintaining (or near to) the PP O2.

...that's a very bad thing.

Let's start with CO2. Plants like it, we don't.

Actually many plants tolerate raised CO₂ worse than we do. It acidifies the water in their leaves. A small amount of enrichment is really good for yield, so you might run the grow areas at 600-800ppm, but (depending on the varieties) once you go above 2000ppm your plants are dying. (Wheat seems to like high CO₂, corn, soy and rice really don't like going above 800ppm. Not sure about salad crops.)

Humans, OTOH, have to go about 10,000ppm (1%) before the air seems stale and uncomfortable. And above 50,000ppm before they get sick. Lethal is around 100,000ppm.

(Similarly with variations in oxygen levels, humidity, etc. Worse, as you lower the air pressure, the acceptable range of values narrows, making it harder to keep them productive.)

I had mentioned argon upthread because argon is an excellent insulator, it has much lower thermoconductivity than nitrogen.

It's heat capacity is rubbish, and that's the key trait for a buffer gas. So you would need a higher percentage of argon to match the performance of nitrogen, and hence a higher overall pressure is required for any given partial-pressure of oxygen. Which is just a waste.

Argon is only used in fire suppression systems because of its high "molecular" weight, it tends to displace N₂/O₂ upwards, smothering a low level fire without the smothering nearby humans. Actually, that might be an option for a Mars habitat. Nitrogen in the habitat air, but keep tanks of argon as part of the active fire suppression system.



[edit:

If you're curious: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.959.3356&rep=rep1&type=pdf (http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.959.3356&rep=rep1&type=pdf)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 12:50 pm
2) fire risk increases if you remove buffer gas. Not a lot, mind you (provided you keep oxygen partial pressure at no more than sea level),

Once again, that's the opposite of how it works.

If you keep the percentage of oxygen in the air constant, then lowering the overall pressure has only a small effect on flammability and ignition risk.

...
I can tell you've never tried to start a fire at high altitude.

I remember earlier you asserted that flammability was constant as long as the oxygen percentage was the same, a claim that was disproven with your own sources.

These two things are facts:

1) keep Oxygen percentage the same but reduce total pressure, and flammability goes down

2) keep oxygen partial pressure the same and reduce buffer  gas pressure, and flammability goes up.

Logically, somewhere in between there, you can increase oxygen percentage somewhat and keep flammability constant provided you reduce the partial pressure as well (which means reducing total pressure), thus allowing you to safely reduce the partial pressure of the buffer gas even more than your oxygen partial pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 01:19 pm
Nomadd is right that people are fine at Cusco, 9.5psi.

And it's harder to light fires there. Which means you can afford to reduce buffer gas partial pressure even more.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Johnnyhinbos on 01/20/2017 01:25 pm
If you keep the percentage of oxygen in the air constant, then lowering the overall pressure has only a small effect on flammability and ignition risk.
If you keep the partial pressure of oxygen constant, then flammability varies strongly with changes in overall pressure.
Yes, it's important folks think in terms of partial pressures and not percentages.

{laughs} That's the opposite of what I said.

When it comes to fire risk, you really have to pay attention to percentages. Hence...

As I mentioned upthread there's a lot to be gained from reducing the overall pressure while maintaining (or near to) the PP O2.

...that's a very bad thing.

Let's start with CO2. Plants like it, we don't.

Actually many plants tolerate raised CO₂ worse than we do. It acidifies the water in their leaves. A small amount of enrichment is really good for yield, so you might run the grow areas at 600-800ppm, but (depending on the varieties) once you go above 2000ppm your plants are dying. (Wheat seems to like high CO₂, corn, soy and rice really don't like going above 800ppm. Not sure about salad crops.)

Humans, OTOH, have to go about 10,000ppm (1%) before the air seems stale and uncomfortable. And above 50,000ppm before they get sick. Lethal is around 100,000ppm.

(Similarly with variations in oxygen levels, humidity, etc. Worse, as you lower the air pressure, the acceptable range of values narrows, making it harder to keep them productive.)

I had mentioned argon upthread because argon is an excellent insulator, it has much lower thermoconductivity than nitrogen.

It's heat capacity is rubbish, and that's the key trait for a buffer gas. So you would need a higher percentage of argon to match the performance of nitrogen, and hence a higher overall pressure is required for any given partial-pressure of oxygen. Which is just a waste.

Argon is only used in fire suppression systems because of its high "molecular" weight, it tends to displace N₂/O₂ upwards, smothering a low level fire without the smothering nearby humans. Actually, that might be an option for a Mars habitat. Nitrogen in the habitat air, but keep tanks of argon as part of the active fire suppression system.
So much of what you said is wrong (though I wouldn't say "rubbish" ). However I don't think it's worth cluttering up this thread with a debate so I'll leave it at that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 01:33 pm
I'm sorry for diverting this thread so hard. :(
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 03:46 pm
So much of what you said is wrong (though I wouldn't say "rubbish"). However I don't think it's worth cluttering up this thread with a debate so I'll leave it at that.

{shrug} Either reply or don't reply. Don't do... that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/20/2017 04:03 pm
I don't think the atmospheric pressure used will have all that much impact on the physical design of the colony.
I also don't expect people to go out all that much.  Most of the time will be spent 'indoors', providing services between the colonists, sleeping, eating and entertaining.  Quite a bit of work will be done furnishing the raw habitats provided by tunneling (or by prefab domes, ice domes and other variants).
In my 10000 people small town (Otterburn Park, Canada), I see precious few people going out for evening walks, and in bad weather conditions, be they from cold or heat, this quickly goes down to 0.
So the question of locks may be secondary as they may not see all that much usage.  In particular if the industrial works are also underground in pressurized areas.  I do see rovers moving about for exploration purposes, but a lot of work can be done with just a few dozen rovers and crews.

Is there a 'standard' design that exists for vertical airlock doors?  I have been using the ISS cargo doors, and these might be fine in 0g, but not that practical in Mars gravity.

Are there any serous objections to underground storage tanks of fuel for the ITS spaceship, if we start with the premise that cave are fairly simple to dig, and we have concrete to make them 'airtight'?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 04:08 pm
I remember earlier you asserted that flammability was constant as long as the oxygen percentage was the same, a claim that was disproven with your own sources.

They showed (with graphs and charts and everything) that if you halve the total air pressure, the same fire risk occurs at around 24% O₂. 21% to 24%. Barely moved as a percentage. But that means O₂ partial pressure for constant flammability risk and burn rate are nearly linear with total pressure.

Increasing the percentage of oxygen has a vastly larger effect on flammability than overall pressure. Reducing the percentage of buffer gas increases the risk of fire, if you don't also proportionately reduce the level of oxygen. The percentage effect dominates the pressure effect. You can't get a significant reduction in total pressure without increasing fire risk before you hit biological limits for oxygen partial pressure.

[Edit: Stupidly, I miswrote the first line in the last paragraph to mean the complete opposite of my point. Fixed.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 04:20 pm
Never said it was proportional. Anyway, I'm glad you've seen my point. Let's get back to the topic at hand.
Title: Re: Envisioning Amazing Martian Habitats
Post by: alexterrell on 01/20/2017 04:33 pm
I remember earlier you asserted that flammability was constant as long as the oxygen percentage was the same, a claim that was disproven with your own sources.

They showed (with graphs and charts and everything) that if you halve the total air pressure, the same fire risk occurs at around 24% O₂. 21% to 24%. Barely moved as a percentage. But that means O₂ partial pressure for constant flammability risk and burn rate are nearly linear with total pressure.

Increasing the partial pressure has a vastly larger effect on flammability than overall pressure. Reducing the percentage of buffer gas increases the risk of fire, if you don't also proportionately reduce the level of oxygen. The percentage effect dominates the pressure effect. You can't get a significant reduction in total pressure without increasing fire risk before you hit biological limits for oxygen partial pressure.
That makes sense and doesn't necessarily disagree with Robotbeat above. The deadly Apollo fire of 196X suggests partial pressure is more important.

The third variable is of course the flammability of surrounding materials. (A nice piece in Andy Weir's "The Martian" where he can't find anything to make a fire with). So how much buffer gas can we ditch given the most flammable things will be in the kitchen?
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 01/20/2017 04:43 pm
I can't believe people are still arguing about atmospheric pressure in our Mars colony...

I'm pretty sure that pressure and composition will be very close to those on Earth, just because you're not going to change more variables than you absolutely have to if you want to live long and healthy there. The lower gravity is a given, but we will need pressure vessels anyway, so keeping the pressure and atmospheric composition earth-like is a very sane thing to do. Having very fit and healthy people living in a lower-pressure atmosphere with higher oxygen content for a while is totally different from people living in it for decades, including children and pregnant women.

And then there are just practical advantages of a denser atmosphere, like less noise from fans for cooling due to better thermal properties. Or not having to use pressure cookers for everything in the kitchen. Or not to suffer from dry skin for the rest of your life. All of this is inconsequential for short missions with fighter-pilot astronauts, not so much for a colony.

Dealing with the lower gravity will be hard enough (and I still think habitat volume should be oriented vertically instead of horizontally to force people to move up and down all day in the lower gravity to get some natural exercise and to exploit air movement through temperature differences instead of noisy fans). We definitely don't want to introduce more problems than we got on our hands anyway.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 04:47 pm
By the way, half of sea level pressure is at about 19000ft on Earth (7.5-8psi). This is much higher than any permanent cities on Earth (16500ft), although much lower than Everest, which people regularly climb without oxygen. But as Paul451 pointed out, you can safely increase the oxygen concentration to 24% at that total pressure while maintaining a flammability the same as sea level. That gives you an oxygen partial pressure equivalent to about 15000ft, and there ARE multiple permanent human settlements/cities at or around that altitude. Although I'd recommend houses inside the main hab be pressurized a little higher for comfort... It's always a good idea for internal houses to have their own pressure vessels for safety reasons anyway. But the pressure difference may only be 1-2psi.

That reduces leak rates dramatically, increases main hab structural factor of safety by 2x (or makes it much cheaper), reduces energy needed for air locks, speeds air lock press and depress, and reduces prebreathing requirements dramatically compared to sea level, and dramatically cuts the damage to tissue (from the bends) due to sudden pressure loss.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 04:50 pm
I can't believe people are still arguing about atmospheric pressure in our Mars colony...

I'm pretty sure that pressure and composition will be very close to those on Earth, just because you're not going to change more variables than you absolutely have to if you want to live long and healthy there. The lower gravity is a given, but we will need pressure vessels anyway, so keeping the pressure and atmospheric composition earth-like is a very sane thing to do. Having very fit and healthy people living in a lower-pressure atmosphere with higher oxygen content for a while is totally different from people living in it for decades, including children and pregnant women.

And then there are just practical advantages of a denser atmosphere, like less noise from fans for cooling due to better thermal properties. Or not having to use pressure cookers for everything in the kitchen. Or not to suffer from dry skin for the rest of your life. All of this is inconsequential for short missions with fighter-pilot astronauts, not so much for a colony.

Dealing with the lower gravity will be hard enough (and I still think habitat volume should be oriented vertically instead of horizontally to force people to move up and down all day in the lower gravity to get some natural exercise and to exploit air movement through temperature differences instead of noisy fans). We definitely don't want to introduce more problems than we got on our hands anyway.
Again, the prejudices of those who live exactly at sea level. What about Mexico City and Denver? Do they not count as "on Earth?" :D are there not people raising families there?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 05:15 pm
Is there a 'standard' design that exists for vertical airlock doors?  I have been using the ISS cargo doors, and these might be fine in 0g, but not that practical in Mars gravity.

Industrial:

(http://www.floodbarriers.com/wp-content/uploads/2014/03/Mvc-015s.jpg)

NASA/Constellation-era:

(https://www.nasa.gov/images/content/170070main_influnarhab02-1024.jpg)

NASA "Chamber A", Space Environment Simulation Laboratory, JSC:

(http://www.space.com/images/i/000/027/785/original/nasa-vacuum-chamber-1.jpg?interpolation=lanczos-none&fit=inside%7C660:*)

(https://i.kinja-img.com/gawker-media/image/upload/s--OPktXeYS--/c_scale,f_auto,fl_progressive,q_80,w_800/1299988856555817289.jpg)

(http://i.imgur.com/AsALWPs.jpg)

NASA Space Power Test Facility, Plum Brook:

(https://www.nasa.gov/sites/default/files/images/312733main_vacuum_chamber_full.jpg)

(http://images.slideplayer.com/23/6877817/slides/slide_4.jpg)

(Can't find a good image of the two main doors. This video (https://youtu.be/00vT_qa2AhY?t=6m15s) is the closest I've found.)



But remember for the last few, the pressure is on the outside trying to get in, not the inside trying to get out, so everything's backwards. Airlock doors always open so the pressure difference pushes them against their own seals. The inner hatch opens into the habitat, the outer hatch opens into the airlock. (So for a sliding door, you'd need enough horizontal room inside the airlock next to the outer opening for the entire mechanism for the outer hatch.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 05:23 pm
The NASA example you give is just an off-the-shelf industrial type door. It's for the "functional mockup" of the inflatable hab at Langley (shipping to a museum, by the way). It's not representative of what a flight door would look like.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 05:25 pm
You can design the doors to work either way. After a problem with the Mercury hatch, we designed them to open in in order to stay shut under pressure. After Apollo 1, we designed them to open out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/20/2017 05:29 pm
Lamontagne,

Actually, marine and submarine hatches are probably a good model for personnel airlocks. And weather-tight "roro" doors on cargo ships are a good model for vehicle airlocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DigitalMan on 01/20/2017 06:16 pm
Nomadd is right that people are fine at Cusco, 9.5psi.

And it's harder to light fires there. Which means you can afford to reduce buffer gas partial pressure even more.

I've done a lot of mountain climbing.  My observation is that many begin to notice changes above 12,000 feet.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/20/2017 06:37 pm
The main colony access area. With some nice coverings over the airlock hatches. Think i'll call it area 451.  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/20/2017 06:39 pm
Another view of area 451
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/20/2017 07:21 pm

Alternatively you need a production plant and power systems that's an order of magnitude larger, in order to produce most of the propellant while the ships are on Mars. That seems extraordinarily wasteful.
Or you feed your chemical industry with the plant output EXCEPT when ships are in port... you'll still need buffer tankage here and there but maybe not tankage you have to keep cold. (because it has stuff in it like longer chain hydrocarbons, esters, alcohols, polypropylene and nylon monomers, etc) You'd have excess oxygen to dispose of since methane is a more important feedstock to "petrochemical" plants than oxygen... but maybe this would work out?

I lost track of the different ways we went off topic since last I posted. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/20/2017 07:33 pm
Quote from: Paul451 link=topic=41427.msg1632918#msg1632u918 date=1484904548

Alternatively you need a production plant and power systems that's an order of magnitude larger, in order to produce most of the propellant while the ships are on Mars. That seems extraordinarily wasteful.
Or you feed your chemical industry with the plant output EXCEPT when ships are in port... you'll still need buffer tankage here and there but maybe not tankage you have to keep cold. (because it has stuff in it like longer chain hydrocarbons, esters, alcohols, polypropylene and nylon monomers, etc) You'd have excess oxygen to dispose of since methane is a more important feedstock to "petrochemical" plants than oxygen... but maybe this would work out?

I lost track of the different ways we went off topic since last I posted. :)
I like it. Just like biological plants on Earth, on Mars industrial chemical plants will produce oxygen as a byproduct of chemical processes used to make structures. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rpapo on 01/20/2017 08:26 pm
Nomadd is right that people are fine at Cusco, 9.5psi.

And it's harder to light fires there. Which means you can afford to reduce buffer gas partial pressure even more.

I've done a lot of mountain climbing.  My observation is that many begin to notice changes above 12,000 feet.
I've lived in Peru, in Arequipa (8,000ft) and Juliaca (12,600ft).  In Arequipa I rarely noticed the altitude.  In Juliaca I would get winded climbing one flight of stairs.  On my several occasions at 16,000 ft, I was glad I wasn't doing much of anything.  The locals, however, took it in stride.  Their main issues with altitude were sunburn by day and freezer burn by night, both of which could be dealt with and neither of which have anything to do with our future Martians.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/20/2017 08:34 pm
Splinter thread:
Airlocks for Mars Colony
https://forum.nasaspaceflight.com/index.php?topic=42098.new#new
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/21/2017 04:49 am
The main colony access area. With some nice coverings over the airlock hatches. Think i'll call it area 451.  ;-)
Both images look good. 2nd image looks like a freight distribution center.

On the 1st image what is the big white area under the blue hang over at the end of the building?

Some suggestions-
The blue hang over would collect dust on top between it's self and the roof, needs to be sloped down from the top so dust would fall off..  For high wind they will need to be attached to the ground at points that hang over at given intervals. Perhaps more spacing between each docking port for wider trucks.

2nd image-
The garages ( transparent ) and the docks behind them, should they be replaced with airlocks for trucks to enter the building behind them and have that as the garage.?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/21/2017 06:07 am
Regarding the propellant plant, I believe it will be incorporated in the first unmanned IST that lands on Mars.

No need to extract and set up the "factory": it comes pre-installed in its own housing, the IST, which already has the necessary oxygen and methane tanks to store the production of fuel.

Now all that remains to do is feed the IST with Martian water...

So any airlock on a Mars habitat (whether for crew or entire vehicles) will include two non-pressure-changing chambers, one inside at habitat pressure, one outside at Mars pressure. (As shown in one of my crude sketches.)

I think the same will be true even of suit-locks and vehicle docking-ports. They will be inside closable, but unpressurised, "sheds" attached to the airlock. This helps with dust exclusion, reduces sun damage, and should reduce thermal cycling a little.

Sheds either side of the airlock make a lot of sense. Very nice sketches. I would say the outer shed should just have an unlocked door that can be quickly opened from either side, in case of emergencies.

Few people seem to have any difficulty in Cusco after a couple of days at 9.5 psi.

Ugh, unless you're me in 1987 after too many pisco sours in Lima the night before. Arriving in 10,000 foot  Cusco was, er, unpleasant. Though I will say just a day later found me mountain biking to Machu Picchu, so it is amazing how the human body recovers.

I.e. exactly what Nomadd said: "after a couple of days"... He has very good posts, they deserve to be read.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/21/2017 06:45 am
The BFS is expected to be usable for 12 flights to Mars. Leave it at Mars after the 12th flight and use it's tanks as storage tanks for propellants made on Mars. Perhaps better than sending it back to Earth for recycling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/21/2017 07:34 am
The BFS is expected to be usable for 12 flights to Mars. Leave it at Mars after the 12th flight and use it's tanks as storage tanks for propellants made on Mars. Perhaps better than sending it back to Earth for recycling.

Possible but that is 25 years after its first launch.

But I guess that the first one or two cargo ships never get back and can be used that way. After that they need to find a storage solution.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/21/2017 02:46 pm
Regarding the propellant plant, I believe it will be incorporated in the first unmanned IST that lands on Mars.
No need to extract and set up the "factory": it comes pre-installed in its own housing, the IST, which already has the necessary oxygen and methane tanks to store the production of fuel.

Two issues: That requires the ITS ships will be on Mars for long enough for entire the propellant production cycle. Either they are on Mars for two+ years, or the propellant plant must have an order of magnitude higher throughput (which is hard to reconcile with "fits inside the ITS ship.)

Second: It means every ITS ship carries the mass of the fuel production plant, every time. Repeatedly carrying it to and from Earth when you could be carrying other cargo to Mars, and returning to Earth lighter/faster. Seems more logical to send it once and leave it there. The only added cost/mass is the tanks for intersynodal fuel production. (You can send Refinery_Mass + Extra_Tanks once, or you have to send Refinery_Mass every single trip. In the latter case, the number of trips before you're wasting mass is 1 + Extra_Tanks / Refinery_Mass. And I suspect that Extra_Tanks < Refinery_Mass, so the number of trips before a permanent facility wins is ~1.)

If early ITS ships are being left on Mars, partially test missions, partially equipment drops, you might build the propellant processing plant into one of them and use the others as spare tanks. But I don't get the impression that Musk intends to (deliberately) have expendable versions of ITS during development, as they did with F9 and Dragon. HoG is expected to be returned and reused, straight out the box.

So any airlock on a Mars habitat (whether for crew or entire vehicles) will include two non-pressure-changing chambers, one inside at habitat pressure, one outside at Mars pressure. I think the same will be true even of suit-locks and vehicle docking-ports. They will be inside closable, but unpressurised, "sheds" attached to the airlock.
I would say the outer shed should just have an unlocked door that can be quickly opened from either side, in case of emergencies.

That was the intention, there's no reason for a locking door, it's not a pressure vessel. (Even on the inner side, you might have an additional heavy bulkhead door for emergencies, but day-to-day that would be left open and you'd have a non-pressurised internal door to control dust/noise/etc.)

Speaking of which,

Lamontagne,
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1402541;image) (http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1402541;image)

I meant an enclosed shed for the vehicles, not just a canopy. The vehicle docking ports would be inside the shed. Likewise any vehicle airlock, personnel airlocks and suitports. When you pass through the airlocks/suitports/docking-ports, you are still inside an unpressurised room with a simple dust-blocking door, outside of that room is where you step or drive onto Mars' surface.

(Although that's not as visually interesting. Sheds, w00t.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/21/2017 02:55 pm
Not sure if this is any clearer...

Top down view.

Green walls are unpressurised. Heavy black walls are pressurise-containing main walls. Blue segments are pressurisable airlock and bulkhead doors. Vehicles are black/yellow. Spacesuits are black/white.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/21/2017 03:10 pm
Views of air separation plants.

Air liquide:
http://ilab.airliquide.com/award-winning-projects/
Linden, see joined pdf file

Probably not all that large, and we may need to compress the air before cooling it?  Or perhaps cool matian air directly?  Output would drop by 100x perhaps?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/21/2017 03:15 pm
Not sure if this is any clearer...

Top down view.

Green walls are unpressurised. Heavy black walls are pressurise-containing main walls. Blue segments are pressurisable airlock and bulkhead doors. Vehicles are black/yellow. Spacesuits are black/white.

Clear enough.  I'll stick with the canopy though, because I see area 451 more as a bus stop than a garage, and the functions you show are implemented elsewhere in the colony.  Walls and doors are always more trouble than one thinks they will be, IMHO.

Canopy cleaning is by an automated system using compressed mars atmosphere.  I expect the duxt would stick to about any surface, so mechanical cleaning is in order here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: launchwatcher on 01/21/2017 03:37 pm
Not sure if this is any clearer...

Top down view.

Green walls are unpressurised. Heavy black walls are pressurise-containing main walls. Blue segments are pressurisable airlock and bulkhead doors. Vehicles are black/yellow. Spacesuits are black/white.
With the vehicle and pedestrian airlocks arranged like that, someone's going to get run over...  I'd swap the vehicle docking ports and suit locks to separate foot and wheeled paths.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/21/2017 04:10 pm
Not sure if this is any clearer...

Top down view.

Green walls are unpressurised. Heavy black walls are pressurise-containing main walls. Blue segments are pressurisable airlock and bulkhead doors. Vehicles are black/yellow. Spacesuits are black/white.
With the vehicle and pedestrian airlocks arranged like that, someone's going to get run over...  I'd swap the vehicle docking ports and suit locks to separate foot and wheeled paths.
I think the personnel ports should be somewhere else altogether.  Although I expect all these vehicles will be fitted with the latest autopilot software, so probably quite safe, no need to court disaster...
Title: Re: Envisioning Amazing Martian Habitats
Post by: RocketmanUS on 01/21/2017 06:16 pm
Not sure if this is any clearer...

Top down view.

Green walls are unpressurised. Heavy black walls are pressurise-containing main walls. Blue segments are pressurisable airlock and bulkhead doors. Vehicles are black/yellow. Spacesuits are black/white.
Very nice start, I like having the unpressurized bay. Keeps dust out of airlocks and shields from wind. If there is to much dust in the air outside they could still see.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/21/2017 07:53 pm
With the vehicle and pedestrian airlocks arranged like that, someone's going to get run over...  I'd swap the vehicle docking ports and suit locks to separate foot and wheeled paths.

The specific layout wasn't important. It was just to illustrate the idea of having an enclosed outside work area outside the airlocks, rather than having airlocks exiting directly onto the surface. (Or entering directly into the habitat.)

The only thought put into the layout was that the area just inside "airlocks" (vehicle or personnel) will be dusty and should be kept separate from "ports", which won't. Also that banks of ports (suitports or vehicle docking ports) should be behind another bulkhead in case a port leaks, and separate to the prep-area for the airlocks.

However, to your point, I doubt there'd be much mixed traffic. You would only have people walking around in spacesuits when the vehicles are parked, and you would only use the vehicles when everyone is loaded.

(Similarly, the idea of suitports is so you don't have to use a full airlock. So the only time the personnel/EVA airlock would be used is to cycle suits back inside for maintenance. Same with the vehicle docking ports vs vehicle airlock. So you would never see a situation where all four lock-types are in simultaneous use, as I depicted. Generally only one would be in use at any given time.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/22/2017 12:45 pm
Flyover of the completed colony.  10 000 people.
Not yet a fully independent entity, there are probably others nearby.

https://www.youtube.com/watch?v=5j0IEJmXpeA


Comments welcome!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 01/22/2017 04:34 pm
Comments welcome!

Beautiful imagery and you obviously put a lot of work into it.

Would you care to share the schedule and budget necessary  to produce such a facility? How much revenue those 10,000 people will have to produce annually to pay off its construction costs and maintain it?

You know, the really important stuff.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/22/2017 05:44 pm
Comments welcome!

Beautiful imagery and you obviously put a lot of work into it.

Would you care to share the schedule and budget necessary  to produce such a facility? How much revenue those 10,000 people will have to produce annually to pay off its construction costs and maintain it?

You know, the really important stuff.
Glad you liked the animation. The colony would reach the state illustrated sometimes about 2050.  Value would be many billions, more than 5, less than 50.
The progression is based on the geometrical development used in the mining industry (as well as plant construction in the middle East): a small exploration camp (20), followed by a first stage of construction(100-150), a full fledged construction camp(600-1000) used to build billions dollar installations.

As far as numbers go, here are two spreadsheets, one dealing with the expansion of the colony, the other with the details of the construction of underground habitats. The basic premises I use are the SpaceX numbers from the September 2016 presentation.  These are not complete and formal analysis, but I hope you will find numbers you can evaluate and enjoy. 

But they are not as pretty as the video ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/22/2017 08:38 pm
I think it needs a lush some on top of the crater overlooking the crater below and giving a view of the land surrounding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/22/2017 08:41 pm
I think it needs a lush some on top of the crater overlooking the crater below and giving a view of the land surrounding.
Lush Dome!  Jungles take a lot of bandwidth.  The big oval domes are pretty lush, I expect.  I am working on a design for crater wall individual homes, for people who do not want to live with the plebs.

Do you want a waterfall in your jungle dome?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/22/2017 09:28 pm
Lush Dome! Jungles take a lot of bandwidth.

How about regular old agriculture? You had sporting and recreation fields, but I don't think you had any food production.

In soil, you probably need 3-5 square kilometres to feed 10,000 people. Hydroponics, you can reduce that to 1-2 square kilometres. With aeroponics, you can maybe drop that by another half. However, that's will a calorie-focused, ultra-simple diet. Potatoes, sweet potatoes, a few other high density vegetables. If you want animal protein, you'll need more food production (to feed the animals, 10:1 conversion), but not much space if you're willing to copy intensive practices. If you want variety in your diet, then you need low calorie foods, like salad vegetables. That will blow out your land requirements again.

IMO, the majority the pressurised volume of any colony will be food production. Just as the majority of a country (by land area) is farming.

[edit: I R ultra-simply bad at riting]
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/22/2017 09:47 pm
Lush Dome! Jungles take a lot of bandwidth.

How about regular old agriculture? You had sporting and recreation fields, but I don't think you had any food production.

In soil, you probably need 3-5 square kilometres to feed 10,000 people. Hydroponics, you can reduce that to 1-2 square kilometres. With aeroponics, you can maybe drop that by another half. However, that's will a calorie-focused, ultra-simply diet. Potatoes, sweet potatoes, a few other high density vegetables. If you want animal protein, you'll need more food production (to feed the animals, 10:1 conversion), but not much space if you're willing to copy intensive practices. If you want variety in your diet, then you need low calorie foods, like salad vegetables. That will blow out your land requirements again.

IMO, the majority the pressurized volume of any colony will be food production. Just as the majority of a country (by land area) is farming.
Yes indeed.  The lower levels of the habitats are dedicated to farming in intense aeroponics/hydroponics style.  See joined image, that didn't make it into the video.
The large open volumes in the colony are expensive, but perhaps essential? Psychological areas.
I expect there may be outlying farms, and I was partial for a time to plastic bags on the surface.
I don't expect much animal protein for a while, but I may be wrong. It's horrendously inefficient for a Mars colony, IMHO.  And it may be somewhat out of fashion by 2050.

Any type of home that might interest you, in this context?  I'm offering free homes, industries and vehicles to anyone who can provide adequate and convincing descriptions!

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/22/2017 09:50 pm
I think it needs a lush some on top of the crater overlooking the crater below and giving a view of the land surrounding.
Lush Dome!  Jungles take a lot of bandwidth.  The big oval domes are pretty lush, I expect.  I am working on a design for crater wall individual homes, for people who do not want to live with the plebs.

Do you want a waterfall in your jungle dome?
A big dome that has room for thousands of people. Like this, except without so many amusement park rides, more dome-shaped (so you have windows on the side to see outside, instead of just a skylight), apartments for lots of people surrounded by greenery.

(And less structure to block the light.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/22/2017 09:53 pm
You're going to want to have greenery, and it might as well be fruit trees and the like. Dual purpose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/22/2017 10:00 pm
No matter what kind of habitat, you'll want living spaces full of greenery. As someone who grew up in Minnesota and lived almost my entire life there, this makes being stuck inside during winter tolerable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/22/2017 11:27 pm
You're going to want to have greenery, and it might as well be fruit trees and the like. Dual purpose.

I've added greenery to the final building in the video, a large dome that rather ressembles your description.
Title: Re: Envisioning Amazing Martian Habitats
Post by: cro-magnon gramps on 01/23/2017 01:17 am
Something that I have mentioned before, and probably got lost in the conversation: Stem Cell Production of Animal Protein Items... it is already in the experimental stage, and will only become more available as time goes by... for a small colony of 10,000 by the year 2050, I don't see a problem with a portion of the space set aside for this... it won't be a common part of the diet... more like a luxury...
another thing thinking of Robotbeat's comment re greenery... is there a reason why the tubes are so barren and grey... I would have expected more colour and variety, as was in a few spots (murals or led screens)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/23/2017 11:48 am
Something that I have mentioned before, and probably got lost in the conversation: Stem Cell Production of Animal Protein Items... it is already in the experimental stage, and will only become more available as time goes by... for a small colony of 10,000 by the year 2050, I don't see a problem with a portion of the space set aside for this... it won't be a common part of the diet... more like a luxury...
another thing thinking of Robotbeat's comment re greenery... is there a reason why the tubes are so barren and grey... I would have expected more colour and variety, as was in a few spots (murals or led screens)
Stem cell meat, or some form of vat grown protein, is definitively a possibility if it uses significantly less energy to produce.
The tubes are barren because I have a limited amount of time to invest in this project :-)  and adding texture and color requires time and effort, for very little return.  The model has already reached 100 megs and is getting unwieldy as well.

Most of the corridors shown are utility corridors anyway.

But if there is something you would like to see, I would be glad to add it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: cro-magnon gramps on 01/23/2017 07:36 pm
Something that I have mentioned before, and probably got lost in the conversation: Stem Cell Production of Animal Protein Items... it is already in the experimental stage, and will only become more available as time goes by... for a small colony of 10,000 by the year 2050, I don't see a problem with a portion of the space set aside for this... it won't be a common part of the diet... more like a luxury...
another thing thinking of Robotbeat's comment re greenery... is there a reason why the tubes are so barren and grey... I would have expected more colour and variety, as was in a few spots (murals or led screens)
Stem cell meat, or some form of vat grown protein, is definitively a possibility if it uses significantly less energy to produce.
The tubes are barren because I have a limited amount of time to invest in this project :-)  and adding texture and color requires time and effort, for very little return.  The model has already reached 100 megs and is getting unwieldy as well.

Most of the corridors shown are utility corridors anyway.

But if there is something you would like to see, I would be glad to add it.

No, I am happy to leave well enough alone :D I'm working with an 10+ yr old system, on it's last legs and can understand the limits you are up against... We all can't work with 16 cores and 128 gigabits of memory ;) what you are doing is great...

Thx
Gramps...
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 01/23/2017 09:06 pm
Flyover of the completed colony.  10 000 people.
Not yet a fully independent entity, there are probably others nearby.

https://www.youtube.com/watch?v=5j0IEJmXpeA


Comments welcome!
To quote Elon: "People will die."
What happens with the bodies of the dead? Will there be a graveyard? Outside they will probably last to the end of time...
The alternative would be some form of "recycling" or cremation.
Or use the return flight of the ITS to launch the bodies into space. Is it possible to send them into the sun?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 01/23/2017 09:54 pm
Flyover of the completed colony.  10 000 people.
Not yet a fully independent entity, there are probably others nearby.

Comments welcome!
To quote Elon: "People will die."
What happens with the bodies of the dead? Will there be a graveyard? Outside they will probably last to the end of time...
The alternative would be some form of "recycling" or cremation.
Or use the return flight of the ITS to launch the bodies into space. Is it possible to send them into the sun?

Interesting question.

Takes too much delta V to send remains into the sun. Need to do something with them on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/23/2017 09:58 pm
To quote Elon: "People will die."
What happens with the bodies of the dead? Will there be a graveyard? Outside they will probably last to the end of time...
The alternative would be some form of "recycling" or cremation. Or use the return flight of the ITS to launch the bodies into space.

Presumably all of the above. Your family could pay to have you shipped home. They could pay to have you buried. Or they could pay to have you pyrolysed (not cremated) and either scattered to the Martian winds, or recycled into the ag section or gardens in the habitat.

(Hmm, over time, you might see a tradition created of a memorial garden in each colony. One modest garden area where pyrolised remains of the majority of deceased colonists are spread, with small tags on the walls for the most recent few thousand, plus names of historical importance. Slowly building up a soil made up entirely of former colonists, supporting a lush garden on top.)

Is it possible to send them into the sun?

It takes more energy to deorbit someone into the sun than to accelerate them beyond escape velocity.

In other words, it's easier to send them to another star.

[You have to drop very close to zero velocity or else you'll merely go into an eccentric orbit around the sun. So falling into the sun requires a delta-v of 100% of your current velocity, in the opposite direction. But escape velocity is sqrt_2 times your current velocity, in the same direction. Ie, escape velocity is √2*X, you're already doing X, so you need an extra 40% of X to reach escape velocity. 40% vs 100%.]

[edit: spelyng]
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 01/23/2017 10:31 pm
No, I am happy to leave well enough alone :D I'm working with an 10+ yr old system, on it's last legs and can understand the limits you are up against... We all can't work with 16 cores and 128 gigabits of memory ;) what you are doing is great...
I realise this is a side topic but I just wanted to add that people like car designers dabble in very complex renderers to make the product look sketchy :-)

The point is that if you show people a crisp 3d model, people take it too literally and say 'nup, I don't want that.', whereas if it is drawn with sketch lines then people intuitively realise there is wiggle room. "something like this".

It is a bit like avoiding the uncanny valley with human CG as well. Rather than texturing, you might want to go in the other direction like cell shading with sketchy line rendering so no one wonders if that is the real texture or if the final product will look like crisp CG polygons :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/24/2017 02:16 am
No, I am happy to leave well enough alone :D I'm working with an 10+ yr old system, on it's last legs and can understand the limits you are up against... We all can't work with 16 cores and 128 gigabits of memory ;) what you are doing is great...
I realise this is a side topic but I just wanted to add that people like car designers dabble in very complex renderers to make the product look sketchy :-)

The point is that if you show people a crisp 3d model, people take it too literally and say 'nup, I don't want that.', whereas if it is drawn with sketch lines then people intuitively realise there is wiggle room. "something like this".

It is a bit like avoiding the uncanny valley with human CG as well. Rather than texturing, you might want to go in the other direction like cell shading with sketchy line rendering so no one wonders if that is the real texture or if the final product will look like crisp CG polygons :-)
Interesting suggestion.  I did try a first version with the outlines and construction lines turned on, but that really looked bad.  I could try to add even more emphasis, Sketchup is particularly good at this, since it's basically an architectural rendering tool.  Could go for a rotoscoped movie look, for example.

Here is a nice sketch style.  The only pblem is that it takes over 5 minutes to render this image, and there are 10 000 images in the video, so about 90 hours of rendering.
I need a more powerful computer  :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/24/2017 02:27 pm
I need a more powerful computer  :-)
Kickstarter??? :) I love your renders and would be good for a small contribution to the cause.  Have you looked into render farms? It's possible to harness the power of the machines of others...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 01/24/2017 03:00 pm
....
I need a more powerful computer  :-)

Nah. You probably need better and multiple GPUs. Which is more expensive than the rest of the computer combine, even NVM Express M2 SSDs.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/24/2017 04:28 pm
....
I need a more powerful computer  :-)

Nah. You probably need better and multiple GPUs. Which is more expensive than the rest of the computer combine, even NVM Express M2 SSDs.

Two different ways of saying the same thing. But it's amazing what GPUs get used for these days, not just graphics...
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 01/24/2017 07:23 pm

To quote Elon: "People will die."
What happens with the bodies of the dead? Will there be a graveyard? Outside they will probably last to the end of time...
The alternative would be some form of "recycling" or cremation.
Or use the return flight of the ITS to launch the bodies into space. Is it possible to send them into the sun?

Way too much deltaV for the sun

I vote for "reanimation".

The final proof of Musk's Evil Genius!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/24/2017 08:50 pm
To quote Elon: "People will die."
What happens with the bodies of the dead? Will there be a graveyard? Outside they will probably last to the end of time...
The alternative would be some form of "recycling" or cremation.
Or use the return flight of the ITS to launch the bodies into space. Is it possible to send them into the sun?

Quote
Like all Loonies, we conserve our dead—and am truly glad that barbaric custom of burial was left back on old Earth; our way is better. But Davis family does not put that which comes out of processor into our commercial farming tunnels. No. It goes into our little greenhouse tunnel, there to become roses and daffodils and peonies among soft-singing bees. Tradition says that Black Jack Davis is in there, or whatever atoms of him do remain after many, many years of blooming.

Is a happy place, a beautiful place.

-RAH, "The Moon is a Harsh Mistress" (https://books.google.com/books?id=HtuRSsAb2fEC&pg=PA331&lpg=PA331&dq=davis+burial+moon+is+a+harsh+mistress+%22like+all+loonies,+we+conserve+our+dead%22&source=bl&ots=qDxSyxCC3-&sig=_GqGUbS6vNKfBMHWOrmNoIHTawQ&hl=en&sa=X&ved=0ahUKEwjO55jK4NvRAhVsxoMKHaj9Cu4Q6AEIGjAA#v=onepage&q=davis%20burial%20moon%20is%20a%20harsh%20mistress%20%22like%20all%20loonies%2C%20we%20conserve%20our%20dead%22&f=false)

I can't think of a better way, myself...
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 01/25/2017 08:21 am
Get your mates to pose you in a really obscene posture somewhere out on the surface. You could become your own statue and last a thousand years or at least until terraforming takes hold. :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/25/2017 10:16 pm
In cities, palaces and buildings on Earth, architects devote a disproportionate amount of their time and effort to "the entrance".

You can see that all over in the gated entrances to walled cities, palace compounds or large estates, or in the entrance doors, halls and lobbies of houses, office buildings and so forth.

What kind of amazing entrances can we imagine for Mars? The whole thing - form, function, decor, grandeur, you name it....
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/26/2017 12:32 am
https://twitter.com/elonmusk/status/824182024479133698

Quote
Elon Musk ‏@elonmusk

Exciting progress on the tunnel front. Plan to start digging in a month or so.

Not sure if he's being serious or not ...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/26/2017 01:15 am
https://twitter.com/elonmusk/status/824182024479133698

Quote
Elon Musk ‏@elonmusk

Exciting progress on the tunnel front. Plan to start digging in a month or so.

Not sure if he's being serious or not ...
It would seem SpaceX is digging a tunnel between the plant and the parking lot.  http://www.businessinsider.com/elon-musk-tunnel-plans-los-angeles-2017-1

What are his ambitions after than is anyone's guess.  The article mentions he might want to try for the nearest airport...

Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/26/2017 01:23 am
^Thanks, that explains a lot.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 01/26/2017 09:55 am
In cities, palaces and buildings on Earth, architects devote a disproportionate amount of their time and effort to "the entrance".

You can see that all over in the gated entrances to walled cities, palace compounds or large estates, or in the entrance doors, halls and lobbies of houses, office buildings and so forth.

What kind of amazing entrances can we imagine for Mars? The whole thing - form, function, decor, grandeur, you name it....

Airlock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 01/26/2017 11:14 am
In cities, palaces and buildings on Earth, architects devote a disproportionate amount of their time and effort to "the entrance".

You can see that all over in the gated entrances to walled cities, palace compounds or large estates, or in the entrance doors, halls and lobbies of houses, office buildings and so forth.

What kind of amazing entrances can we imagine for Mars? The whole thing - form, function, decor, grandeur, you name it....
This was more WRT the moon, but I speculate a lot of artwork on the surface. Big things, glass statues, 3d printed gothic architecture and panels. Artwork that would never find floorspace on earth. On the moon (and mars), for many decades, the whole surface is your attic.

I see people living in nice, green but crowded environments. Everyone wants to exercise their creativity but where do you store it if your personal space is 2x2x2m? The surface.

If we end up building underground or covering our bases in 10 meters of regolith then the surface can really look like anything at all. popular perception always depicts these bases as sterile and functional but I think the opposite would be true: a canvas that gets painted over and over because you can do anything you like with it. Approaching these bases could be like approaching buckingham palace or an aztec pyramid. Columns. Gargoyles? Gardens and fountains but all done in glass artwork too fragile for earth. (again, this was more of a moon vision. Low gravity and no atmosphere and no bothering with direct sunlight given 2 week nights. You could have things permanently spinning just from the pressure of sunlight. The entire landscape at the lunar poles could be multicolored from all this artwork and the light filtering through it. While locking down the dust why not also build massive murals? )
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 01/26/2017 12:59 pm

If we end up building underground or covering our bases in 10 meters of regolith then the surface can really look like anything at all. popular perception always depicts these bases as sterile and functional but I think the opposite would be true: a canvas that gets painted over and over because you can do anything you like with it. Approaching these bases could be like approaching buckingham palace or an aztec pyramid. Columns. Gargoyles? Gardens and fountains but all done in glass artwork too fragile for earth. (again, this was more of a moon vision. Low gravity and no atmosphere and no bothering with direct sunlight given 2 week nights. You could have things permanently spinning just from the pressure of sunlight. The entire landscape at the lunar poles could be multicolored from all this artwork and the light filtering through it. While locking down the dust why not also build massive murals? )

http://forum.nasaspaceflight.com/index.php?topic=34667.msg1355550#msg1355550
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/26/2017 05:31 pm
Elon Musk said in his Mexico presentation that there will be a labour shortage on Mars for decades. I am pretty sure that colonists will devote their energy to all the practical work necessary rather than building castles in the sky. That being said, I am convinced that they will want to beautify their caves, as posted a few pages back in this thread.   
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/26/2017 06:36 pm
Mars colony is a castle in the sky. Fortified against the elements.

A huge part of the work of the early settlers will be making Mars living attractive. Hence living in glass domes even if it's a little riskier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 01/27/2017 01:37 am
I can imagine hobbies being encouraged such as creating musical instruments from materials at hand. The notion being, filling space without taking much of it up.
Title: Re: Envisioning Amazing Martian Habitats
Post by: darkenfast on 01/27/2017 03:44 am
I can imagine hobbies being encouraged such as creating musical instruments from materials at hand. The notion being, filling space without taking much of it up.
Don't let the Lego fans see this!  Lars probably has a Martian gleam in his eye already.  Actually, maybe they could manufacture Lego(s) out of Martian dirt and export them back to Earth as the one set any REAL collector can't be without!

Edit/Lar: fixed my name.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 01/27/2017 02:01 pm
I can imagine hobbies being encouraged such as creating musical instruments from materials at hand. The notion being, filling space without taking much of it up.

Quality Martian scrimshaw could find quite the market back on Earth...
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 01/27/2017 05:03 pm
Well, just bring the carving tools and the artists and they could go crazy with the excess bamboo growing unnaturally tall in the dome.  8)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/31/2017 02:49 am
So I wonder about carving a dome in the rock underground. Tunnel to the dome top with roadheaders and work their way down. How big of a dome could we expect to be stable on Mars 100m below the surface? I can't seem to find any examples on Earth, so maybe it's not practicle, but lower gravity and seismology on Mars may make it more practicle there. Could subterranean domes be amazing Martian habitats?
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/31/2017 08:44 am
Can't find an example quicky. But there are large dome shaped caves formed by Karst processes with only a small hole on top. If these are stable quite large dome shaped caves should be possible too.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/01/2017 02:33 am
So I wonder about carving a dome in the rock underground. Tunnel to the dome top with roadheaders and work their way down. How big of a dome could we expect to be stable on Mars 100m below the surface? I can't seem to find any examples on Earth, so maybe it's not practicle, but lower gravity and seismology on Mars may make it more practicle there. Could subterranean domes be amazing Martian habitats?

Lunar lava tubes could be gigantic, according to this reference.  I don't see why they would not be quite large on Mars as well.  On problem for mining them is that roadheaders will go very slowly in basaltic rock, which is much harder than the sandstone we explored earlier on the thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/01/2017 04:55 am
Lunar lava tubes could be gigantic, according to this reference.  I don't see why they would not be quite large on Mars as well.  On problem for mining them is that roadheaders will go very slowly in basaltic rock, which is much harder than the sandstone we explored earlier on the thread.

Mining them? Isn't the whole point that they are already open?

Other than scrapping a few surfaces clean or widening the occasional choke-point, the only reason you'd "mine" them is if they were filled with ice. And cutting through ice is easier than cutting through rock.

(I mentioned in one of the other Mars threads (seriously think we should merge and close some of these threads) the possibility that over hundreds of millions of years, ice from water vapour might accumulate in the constant low temperature interiors of lava tubes. Similar to the accumulation at the poles, but with even less seasonal melt. If so, it would make a fantastic combination sheltered living environment and major resource. (And heat sink.))
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/01/2017 11:29 am
Lunar lava tubes could be gigantic, according to this reference.  I don't see why they would not be quite large on Mars as well.  On problem for mining them is that roadheaders will go very slowly in basaltic rock, which is much harder than the sandstone we explored earlier on the thread.

Mining them? Isn't the whole point that they are already open?

Other than scrapping a few surfaces clean or widening the occasional choke-point, the only reason you'd "mine" them is if they were filled with ice. And cutting through ice is easier than cutting through rock.

(I mentioned in one of the other Mars threads (seriously think we should merge and close some of these threads) the possibility that over hundreds of millions of years, ice from water vapour might accumulate in the constant low temperature interiors of lava tubes. Similar to the accumulation at the poles, but with even less seasonal melt. If so, it would make a fantastic combination sheltered living environment and major resource. (And heat sink.))
I expressed myself poorly:  Creating analogs to these hypothetical lava tubes by digging in basalt would be difficult, because basalt is hard and roadheaders will work much more slowly, is what I was trying to say.
I think sandstone caves will be limited by spalling risks, as parts of the wall might detach  over time because the material is not very strong in shear.  I believer the were accidents in Parisian gypsum mines in the 19th century because of this.
So one might expect large artificial caves to have a martian concrete interior layer, making them much more expensive to build.
Using the lava tube directly seems possible, but it's hard to say how useful they will be before even a single one of them has been explored.  Artificial sandstone tunnels are easier to model because they have less unknowns.  So our science is just a little less fictional. 
As a guess, if we find stone on Mars that is somewhere between sandstone and basalt, with good mechanical properties, excavated domes with minimum reinforcement should be able to be made at least 3 times larger than pure compression domes such as the large churches or the Pantheon(58m, 7m walls), so perhaps 150 to 200m across?



Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 02/02/2017 12:53 pm
As a guess, if we find stone on Mars that is somewhere between sandstone and basalt, with good mechanical properties, excavated domes with minimum reinforcement should be able to be made at least 3 times larger than pure compression domes such as the large churches or the Pantheon(58m, 7m walls), so perhaps 150 to 200m across?

So I guess here's another item on the list for downselecting sites for a manned landing...the mechanical properties of the local rock and how close to optimal they are for excavating amazing habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: llanitedave on 02/02/2017 05:16 pm
As a guess, if we find stone on Mars that is somewhere between sandstone and basalt, with good mechanical properties, excavated domes with minimum reinforcement should be able to be made at least 3 times larger than pure compression domes such as the large churches or the Pantheon(58m, 7m walls), so perhaps 150 to 200m across?

So I guess here's another item on the list for downselecting sites for a manned landing...the mechanical properties of the local rock and how close to optimal they are for excavating amazing habitats.


The more you look at these issues the more obvious it becomes that there will need to be extensive boots-on-the-ground exploration, both robotic and human, before we can even think about siting and designing a colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/02/2017 05:46 pm
The more you look at these issues the more obvious it becomes that there will need to be extensive boots-on-the-ground exploration, both robotic and human, before we can even think about siting and designing a colony.

You may wildly underestimate what NASA knows about many things on the ground. Though I agree verification on the ground will be needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 02/03/2017 02:18 am
I am guessing that you would wish to cull any sites in close proximity to impact craters if you seek fracture free stone.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2017 03:37 am
I am guessing that you would wish to cull any sites in close proximity to impact craters if you seek fracture free stone.
I'm not a specialist, but as far as I know all rock is fractured, and full of voids and defects.  Volcanic lava is messy stuff as well.  Craters on Mars are actually good places to find deep alluvial and wind blown deposits, that might be our best bet for relatively uniform materials to dig into.

Even concrete, poured and prepared in nearly ideal conditions, cracks and makes voids.  I'm pretty certain any cave or tunnel will need some kind of leak proofing, possible quite extensive leak proofing.  And any colony will need to provide for continuous leakage, making some new atmosphere continuously.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 02/04/2017 04:47 am
I am talking about fractured rock that would require serious structural support.  Some of the past posts seem to be alluding to minimal support required.  When you bring up alluvial, my first thought is... serious 'timbering' even to work in let alone live in.  I am by no means any sort of expert, I am only expressing what I have seen.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2017 04:51 am
I think it was Lumina who thought a well decorated water cistern might look good.
For some reason, the software demolished the regularity of London's St-Paul's dome, but the results are still interesting, I believe.

The dome is a half torus, about 200m in overall circumference, and 100 in the smaller dimension.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2017 05:19 am
I am talking about fractured rock that would require serious structural support.  Some of the past posts seem to be alluding to minimal support required.  When you bring up alluvial, my first thought is... serious 'timbering' even to work in let alone live in.  I am by no means any sort of expert, I am only expressing what I have seen.

It would be nice to have a geologist joint the forum for a bit and set us straight on rock and such :-)

The Wikipedia article on gale crater in interesting https://en.wikipedia.org/wiki/Gale_(crater) but there are quite a few papers that add detail and show that craters can be interesting sites.  in particular, I think the varied terrain may provide useful ressources, including building sites.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 02/05/2017 01:39 am
I think it was Lumina who thought a well decorated water cistern might look good.
For some reason, the software demolished the regularity of London's St-Paul's dome, but the results are still interesting, I believe.

The dome is a half torus, about 200m in overall circumference, and 100 in the smaller dimension.

Very nice. And you just inspired me to imagine a stained glass dome... imagine that... Mars' own (secular) Cappella Sistina, celebrating not this or that earthly religion but simply the sunlight and the water that make life possible on Earth and on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/05/2017 02:13 am
Think of Burning Man for inspiration:
https://www.youtube.com/watch?v=ZGkaV9IPUXc
(That's arranged by SpaceX early investor Steve Jurvetson.)
Musk is a noted attendee of burning man.
And if you read Kim Stanley Robinson's Mars Trilogy, he talks about the Areophany, a kind of pseudo-religious Mars nativist ideology with its own rites and traditions, including partying. Kind of like Burning Man.

...and there's that infamous questioner from the ITS talk. :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 02/05/2017 03:27 am
Quote
...and there's that infamous questioner from the ITS talk. :D

Wasn't that guy on a rant about the attack of the Port-a-Potties or something?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/05/2017 04:06 am
Quote
...and there's that infamous questioner from the ITS talk. :D

Wasn't that guy on a rant about the attack of the Port-a-Potties or something?

Buried in his rant about a sand and %&*$ storm at Burning Man was a serious topic; sewage processing on Mars.

I hope the future Areophany members will be better able to ask a question in public.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/08/2017 01:51 am
Here is a little graphic I have been working on, dealing with the requirements of a Worldship, or orbital space habitat, that are somewhere between what a planet provides and what a martian base might need to be truly viable.

At 10 000 people for 230 km2, the habitat is at the same density of population as the Earth currently is.  The Sun delivers an average of 46 GW on these 230 km, and 10 000 humans need about 0,3 MW of food.  So the conversion factor is not very good :-)  about 150 000:1

The mass factor is also impressive, at about 1,4e9 tonnes of biome, essentially water, soil and air, for about 800 tonnes of humans...

What could be done to improve this?  And how could it look real good in the process? 
The pdf may be more readable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: llanitedave on 02/08/2017 05:22 am
I am talking about fractured rock that would require serious structural support.  Some of the past posts seem to be alluding to minimal support required.  When you bring up alluvial, my first thought is... serious 'timbering' even to work in let alone live in.  I am by no means any sort of expert, I am only expressing what I have seen.

It would be nice to have a geologist joint the forum for a bit and set us straight on rock and such :-)

The Wikipedia article on gale crater in interesting https://en.wikipedia.org/wiki/Gale_(crater (https://en.wikipedia.org/wiki/Gale_(crater)) but there are quite a few papers that add detail and show that craters can be interesting sites.  in particular, I think the varied terrain may provide useful ressources, including building sites.

There have been a few that have posted here on these issues, including yours truly.  As I've mentioned before, the only way to know for sure is to do the ground work on the candidate sites.  The rock WILL be fractured -- very hard volcanic rock will be more fractured than softer rock, in general, but local impact and groundwater history both will modify those generalities into specifics.  Dissolved minerals in moving groundwater can seal fractures over time.  They can also dissolve previous seals and open the fractures back up again.

Some of the most structurally sound rock I've seen underground was in relatively soft, partly clay-altered, non-welded tuff.  There does seem to be some of that on Mars, but it's not extensive.  The thing to remember is that nearly all of the rock formations on Mars, whether volcanic or sedimentary, are far older than their analogues on Earth, and they've had much more time to be subject to impact shocks.

Clays may indeed be a good bet, but the bottom line is that we're just going to have to do the leg work.  There are no shortcuts to a site characterization, and we won't be able to reliably choose a settlement site without one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/08/2017 04:14 pm

There have been a few that have posted here on these issues, including yours truly.  As I've mentioned before, the only way to know for sure is to do the ground work on the candidate sites.  The rock WILL be fractured -- very hard volcanic rock will be more fractured than softer rock, in general, but local impact and groundwater history both will modify those generalities into specifics.  Dissolved minerals in moving groundwater can seal fractures over time.  They can also dissolve previous seals and open the fractures back up again.

Some of the most structurally sound rock I've seen underground was in relatively soft, partly clay-altered, non-welded tuff.  There does seem to be some of that on Mars, but it's not extensive.  The thing to remember is that nearly all of the rock formations on Mars, whether volcanic or sedimentary, are far older than their analogues on Earth, and they've had much more time to be subject to impact shocks.

Clays may indeed be a good bet, but the bottom line is that we're just going to have to do the leg work.  There are no shortcuts to a site characterization, and we won't be able to reliably choose a settlement site without one.

So a cautious designer of Martian underground habitats, conceptualizing before any site work is done, should plan on having fractured rock, and on having to add a certain amount of reinforcement on the interior of his tunnel, as it is likely that bits of the roofing will fall off.  The designer should also expect the rock to be at least a little porous, due to fractures, and therefore the reinforcement should also act as a airtight system.

Seems correct as an interpretation?
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/08/2017 10:30 pm
http://www.unmannedspaceflight.com/index.php?showtopic=8179

unmannedspaceflight forum has the above thread with high-quality Mars terrain views and videos produced from HiRISE DTMs. In particular, check out this video:

https://www.flickr.com/photos/136797589@N04/31336485263/

Think what this means in term of finding a place to build a well-protected base with minimal effort (minimum digging/earthwork). There are tons of depressions and/or ridges where most of the "base" structure already exist. All that needs to be done is to bulldoze the dirt until solid rock is reached, then erect walls/roof, and with more bulldozing pile up regolith on/around them.

(The depression in the video is actually way too deep for an initial base, it's hundreds of meters deep and, if covered, can house a "base" with a population of a large city. Initial base can pick any suitable smaller depression. Say, a crater.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: llanitedave on 02/09/2017 12:10 am

There have been a few that have posted here on these issues, including yours truly.  As I've mentioned before, the only way to know for sure is to do the ground work on the candidate sites.  The rock WILL be fractured -- very hard volcanic rock will be more fractured than softer rock, in general, but local impact and groundwater history both will modify those generalities into specifics.  Dissolved minerals in moving groundwater can seal fractures over time.  They can also dissolve previous seals and open the fractures back up again.

Some of the most structurally sound rock I've seen underground was in relatively soft, partly clay-altered, non-welded tuff.  There does seem to be some of that on Mars, but it's not extensive.  The thing to remember is that nearly all of the rock formations on Mars, whether volcanic or sedimentary, are far older than their analogues on Earth, and they've had much more time to be subject to impact shocks.

Clays may indeed be a good bet, but the bottom line is that we're just going to have to do the leg work.  There are no shortcuts to a site characterization, and we won't be able to reliably choose a settlement site without one.

So a cautious designer of Martian underground habitats, conceptualizing before any site work is done, should plan on having fractured rock, and on having to add a certain amount of reinforcement on the interior of his tunnel, as it is likely that bits of the roofing will fall off.  The designer should also expect the rock to be at least a little porous, due to fractures, and therefore the reinforcement should also act as a airtight system.

Seems correct as an interpretation?


That's a safe starting point, I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2017 01:43 am
http://www.unmannedspaceflight.com/index.php?showtopic=8179

unmannedspaceflight forum has the above thread with high-quality Mars terrain views and videos produced from HiRISE DTMs. In particular, check out this video:

https://www.flickr.com/photos/136797589@N04/31336485263/

Think what this means in term of finding a place to build a well-protected base with minimal effort (minimum digging/earthwork). There are tons of depressions and/or ridges where most of the "base" structure already exist. All that needs to be done is to bulldoze the dirt until solid rock is reached, then erect walls/roof, and with more bulldozing pile up regolith on/around them.

(The depression in the video is actually way too deep for an initial base, it's hundreds of meters deep and, if covered, can house a "base" with a population of a large city. Initial base can pick any suitable smaller depression. Say, a crater.)
Great visual reference. Thanks.  'All that needs to be done' is something of a simplification.  A large bulldozer actually requires quite a bit of energy to operate, and digging down to the bedrock can be a lot of work.  The main cost of building a colony is likely to be the structure and the leak proofing system required to keep it airtight.  So whatever is the simplest way to create that will win out.  It would be nice to see a calculation of what is actually required to build a trench, cap and cover system, as compared to a tunnel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2017 02:23 am
How about food domes?

These are thin plastic membranes filled with water, with a very low pressure gas between the two sheets.  The second sheet is transparent to infra red from the outside, but relatively (very?) opaque from the inside.  The bottom layer may be insulated from the soil, if needed.  There would be as little heat loss as possible, with the maximum solar heat gain.  I guess the pressure might be quite low inside?

If supplied with enough dissolved minerals, oxygen, nitrogen, CO2, etc could these produce some form of bulk food, that could be processed at the colony?
Would life get zapped by radiation?  Would the water help to mitigate this?

I imagine these rather like the large irrigation circles, that can be found in arid areas of most of the world these days.

The plastic would come from Earth at first, but be produced in situ from CH4 as soon as possible.  There might be thousands of these, lasting for a few years before being replaced, 'harvested' using pumps and pipes.  I believe there are some CO2 capture schemes somewhat along these lines.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/09/2017 07:49 am
http://www.unmannedspaceflight.com/index.php?showtopic=8179

unmannedspaceflight forum has the above thread with high-quality Mars terrain views and videos produced from HiRISE DTMs. In particular, check out this video:

https://www.flickr.com/photos/136797589@N04/31336485263/

Think what this means in term of finding a place to build a well-protected base with minimal effort (minimum digging/earthwork). There are tons of depressions and/or ridges where most of the "base" structure already exist. All that needs to be done is to bulldoze the dirt until solid rock is reached, then erect walls/roof, and with more bulldozing pile up regolith on/around them.

(The depression in the video is actually way too deep for an initial base, it's hundreds of meters deep and, if covered, can house a "base" with a population of a large city. Initial base can pick any suitable smaller depression. Say, a crater.)
Great visual reference. Thanks.  'All that needs to be done' is something of a simplification.  A large bulldozer actually requires quite a bit of energy to operate, and digging down to the bedrock can be a lot of work.  The main cost of building a colony is likely to be the structure and the leak proofing system required to keep it airtight.

Yes, when I say it's "easy", it's a relative term. "Easy" relative to building a habitat on a flat plain.
A lot of research and preparation is needed no matter what kind of base will be chosen.
Earthmoving equipment needs to be designed to be light, versatile and durable. So, not a "big bulldozer" for the first base. Maybe a small bulldozer, or possibly it will be a machine which can do more than one operation.
A huge research area is to design a chemical/manufacturing plant which can take in raw materials and produce O2 / N2 / fibers / concrete / steel / aluminum / glass / paints / resins / ..., all in a light and durable package. The equipment we have on Earth is optimized to produce large amounts of relatively few kinds of products, to achieve competitive costs. First Mars bases will have quite different requirements.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/09/2017 08:00 am
The designer should also expect the rock to be at least a little porous, due to fractures, and therefore the reinforcement should also act as a airtight system.

My gut feeling is that it's easy to achieve airtightness with materials designed for the task. Some polymers which you can "paint" over prepared rock walls/floors, then cover them with fabric/foil, then paint this again. Then add buffer material (concrete?) to protect this airtight layer from mechanical damage.

Something like this already exists as cement repair/reinforcement polymers. I've seen some quite cool polyurethane-based ones. They are designed to penetrate deep into smallest cracks and pores, then solidify.

https://www.youtube.com/watch?v=fcAj9n3DbkQ
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/09/2017 09:13 am
Earthmoving equipment needs to be designed to be light,

Earthmoving equipment needs traction to counter inertia, which means it needs down-force, which means it needs weight.

Moving 100 tonnes of material on Mars has the same inertia as it does on Earth, but the vehicle has one-third the down-force, hence less traction. Cutting through several metres of Martian regolith with a bucket has the same mechanical resistance as it does on Earth, but the vehicle has one-third the down-force, hence poorer holding.

"Light" earthmoving equipment on Mars is probably bad at moving earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/09/2017 09:14 am
How about food domes?
The plastic would come from Earth at first, but be produced in situ from CH4 as soon as possible.

Heh. How about bioplastic? Close the circle.

[Aside: No matter how well insulated, if the bio-bubbles admit sunlight, then the internal temperature will swing wildly each day without some kind of thermal mass, and probably a pumped thermal regulator system.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/09/2017 09:25 am
Here is a little graphic I have been working on, dealing with the requirements of a Worldship, or orbital space habitat, that are somewhere between what a planet provides and what a martian base might need to be truly viable.
[...]
What could be done to improve this?  And how could it look real good in the process? 

I can see the relevance to Mars habs, but you might still want to bump it to its own thread under Advanced Concepts to allow a more general discussion.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 02/09/2017 09:50 am
Earthmoving equipment needs to be designed to be light,

Earthmoving equipment needs traction to counter inertia, which means it needs down-force, which means it needs weight.

Moving 100 tonnes of material on Mars has the same inertia as it does on Earth, but the vehicle has one-third the down-force, hence less traction. Cutting through several metres of Martian regolith with a bucket has the same mechanical resistance as it does on Earth, but the vehicle has one-third the down-force, hence poorer holding.

"Light" earthmoving equipment on Mars is probably bad at moving earth.

Agreed. We solve this on earth in two ways, not caring about the weight of necessary components, and adding weight where necessary (the back of cranes, for example, often have counterweights that have no other mechanical function)

On Mars, initially, we will have light necessary components (due to transport) and will have to overcompensate by adding native materials as counterweights... we'll have to provide lightweight compartments to add regolith or water to, placed in strategic places.

On Mars, eventually, this won't be as much of an issue, as native materials used for things like structural components (frames and suchlike) or even mechanicals (track links) will tend to be heavy since the materials won't be as sophisticated, hence not as strong per unit mass...

I kind of don't really see this as a major problem, just as something we need to make sure we don't forget.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 02/09/2017 09:54 am
How about food domes?
The plastic would come from Earth at first, but be produced in situ from CH4 as soon as possible.

Heh. How about bioplastic? Close the circle.

[Aside: No matter how well insulated, if the bio-bubbles admit sunlight, then the internal temperature will swing wildly each day without some kind of thermal mass, and probably a pumped thermal regulator system.]

Agreed. Maybe have the bubbles have two layers inside, with the bottom layer being just water, that is transported via (piping and pumps) to and from thermal reservoirs. During the day cold is admitted and warm taken away, during the night, vice versa. The day's cooling, plus some makeup heat due to thermal losses, provides the night's warming.

I see this as not a difficult problem, just one that we need to remember.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2017 10:58 am
How about food domes?
The plastic would come from Earth at first, but be produced in situ from CH4 as soon as possible.

Heh. How about bioplastic? Close the circle.

[Aside: No matter how well insulated, if the bio-bubbles admit sunlight, then the internal temperature will swing wildly each day without some kind of thermal mass, and probably a pumped thermal regulator system.]

Agreed. Maybe have the bubbles have two layers inside, with the bottom layer being just water, that is transported via (piping and pumps) to and from thermal reservoirs. During the day cold is admitted and warm taken away, during the night, vice versa. The day's cooling, plus some makeup heat due to thermal losses, provides the night's warming.

I see this as not a difficult problem, just one that we need to remember.
The bubbles illustrated are full of water.  They are water bags.  This should give about 1000 times the thermal inertia of the equivalent volume of air, so swings should not be that important.  To be any use, these bubbles need to be thermally neutral, so not too many loses during the night.  This means that they need to be heated in the first place at least once, to reach their equilibrium temperature.

Are water biomes as productive as air biomes in terms of food production?  How much 'product' could we expect from such a bubble?  These ones are an arbitrary 28m in diameter, so using an average of about 120 W/m2 of illumination they receive 73 kWh of sunlight per day.  The average human uses 2500 kilocalories per day, or about 3 kWh.  If we put photosynthetic efficiency at 5%, then we would need at least two of these per colonist?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/09/2017 11:40 am
"Light" earthmoving equipment on Mars is probably bad at moving earth.
Agreed. We solve this on earth in two ways, not caring about the weight of necessary components, and adding weight where necessary (the back of cranes, for example, often have counterweights that have no other mechanical function)
[...]
I kind of don't really see this as a major problem, just as something we need to make sure we don't forget.

I originally commented as a "just something we need to make sure we don't forget", since I'd previously suggested bulk-loading for these kinds of vehicles to compensate for the reduced gravity/traction, but I realised after I posted that it just makes the problem worse for many applications.

Again, inertia is the same, traction is reduced. Increasing the mass to compensate for reduced traction increases inertia by nearly three-fold of that weight. That way lies madness.

No. Vehicles intended to do earthworks on Mars will need to be designed more like ice/snow-moving vehicles. Huge traction areas. Big bubble wheels or super-wide tracks. However, the surface of Mars is vastly harsher than snow/ice and so these will be high-wear items. So an early step is to develop a type of wheel-skin and/or track-plate that can be easily built from locally sourced materials.

(https://thumbs.dreamstime.com/z/special-snow-vehicle-ratrak-snowcat-4501394.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 02/09/2017 12:14 pm
Inertial forces only resist acceleration. Slow movement at constant velocity is largely resisted by viscous and friction forces. Gravity has an effect on those, although the interaction is probably complex.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 02/09/2017 05:45 pm
Lightweight equipment works as long as you can provide a stable center of gravity and as Sghill pointed out with regards to a backhoe, leverage.  Trail building contractors like trackhoes because they can literally make their work area as they go... and they can go to extreme areas.

https://video.search.yahoo.com/yhs/search?fr=ymyy-t-999&hsimp=yhs-att_001&hspart=att&p=extreme+trackhoe+videos#id=3&vid=eddfcd6411b6a965efd6ee6adc4ae338&action=view (https://video.search.yahoo.com/yhs/search?fr=ymyy-t-999&hsimp=yhs-att_001&hspart=att&p=extreme+trackhoe+videos#id=3&vid=eddfcd6411b6a965efd6ee6adc4ae338&action=view)

If you have to ship equipment to Mars, there is something to be said for the slower-lighter excavator options.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2017 09:41 pm
Thinking about the food dome, It will need to lose every night almost all the energy it gained during the day or it will cook.  The energy conversion of chlorophyll is not very good, just a few percent.  All the rest of the energy gain must be lost to keep the system in thermal equilibrium.  The interest of water is that for a 73 kWh gain the thermal gain will be, for a 28m diameter dome, Q=mcpdt, where m is about 1 000 000 kg and cp is 4.18 kJ/kg*K, about 0,06 degrees K.  So during the night, temperature change will be minimal.  If it was air, then the temperature swings would be much higher.
I have added a connection/harvesting/control module.  Vehicles might pass from one to the other to collect biomass and inject nutrients, or the might be pipelines connecting the domes.

Is there a more efficient way than plant/plancton photosynthesis to produce food?  This seems like a wasteful system, but I don't see anything working as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 02/09/2017 09:45 pm
Try this

Quorn (https://en.wikipedia.org/wiki/Quorn#Production)

Still needs glucose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/09/2017 09:58 pm
We have better suited threads for food production in the Mars section. To produce algae, pipes or hoses are probably the best system. The individual pipe is small and very little structural mass is needed for pressure.

I have seen setups for algae growth at the Uni where my daughter studied.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 02/09/2017 09:58 pm
The evolution of chlorophyll is an interesting topic. It probably wasn't the first molecule to capture energy from sunlight, but it was much more efficient than the method used when the earth was purple (http://www.livescience.com/1398-early-earth-purple-study-suggests.html)
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 02/09/2017 10:07 pm
Oh and if you are tessellating domes hexagonal packing is much more area efficient. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 02/09/2017 10:33 pm
http://www.unmannedspaceflight.com/index.php?showtopic=8179

unmannedspaceflight forum has the above thread with high-quality Mars terrain views and videos produced from HiRISE DTMs. In particular, check out this video:

https://www.flickr.com/photos/136797589@N04/31336485263/

Think what this means in term of finding a place to build a well-protected base with minimal effort (minimum digging/earthwork). There are tons of depressions and/or ridges where most of the "base" structure already exist. All that needs to be done is to bulldoze the dirt until solid rock is reached, then erect walls/roof, and with more bulldozing pile up regolith on/around them.

(The depression in the video is actually way too deep for an initial base, it's hundreds of meters deep and, if covered, can house a "base" with a population of a large city. Initial base can pick any suitable smaller depression. Say, a crater.)

Thanks for that link!!!

If anyone is interested, I found that the simplest way to deal with these is to import them into Blender (using varying degrees of resolution).  From there you can export them in the object format of your choice for just about any 3D app.  The image below is a long strip that comprises around a half million polys (lowest resolution).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/09/2017 10:51 pm
All that needs to be done is to bulldoze the dirt until solid rock is reached, then erect walls/roof, and with more bulldozing pile up regolith on/around them.

"All that needs to be done"...  :-)

Why would you want to bulldoze away a lot of dirt to reach solid rock if you can easily drive up to any rockface at the bottom of any hill?

Why would you want to transport wall and roof building material all the way from Earth if you can dig a tunnel and thereby get solid walls and "roofs" from abundant on-site material?

Why would you want to pile up regolith around walls and roof if a tunnel comes with as much regolith around it as you could possibly want?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2017 11:32 pm
Try this

Quorn (https://en.wikipedia.org/wiki/Quorn#Production)

Still needs glucose.
So it's just an intermediate step and we still need the sunlight and some form of surface enclosure?  Or a nuclear reactor that makes light, which pretty much boils down to the same thing?  I'm just trying to find out if I need to surround the illustration of  my Mars base with km2 of greenery, either is soft of rigid domes, or if there is another way.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2017 11:34 pm
http://www.unmannedspaceflight.com/index.php?showtopic=8179

unmannedspaceflight forum has the above thread with high-quality Mars terrain views and videos produced from HiRISE DTMs. In particular, check out this video:

https://www.flickr.com/photos/136797589@N04/31336485263/

Think what this means in term of finding a place to build a well-protected base with minimal effort (minimum digging/earthwork). There are tons of depressions and/or ridges where most of the "base" structure already exist. All that needs to be done is to bulldoze the dirt until solid rock is reached, then erect walls/roof, and with more bulldozing pile up regolith on/around them.

(The depression in the video is actually way too deep for an initial base, it's hundreds of meters deep and, if covered, can house a "base" with a population of a large city. Initial base can pick any suitable smaller depression. Say, a crater.)

Thanks for that link!!!

If anyone is interested, I found that the simplest way to deal with these is to import them into Blender (using varying degrees of resolution).  From there you can export them in the object format of your choice for just about any 3D app.  The image below is a long strip that comprises around a half million polys (lowest resolution).
If you find an area you like, do you think you could save it as a sketchup file and send it my way?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2017 11:49 pm
We have better suited threads for food production in the Mars section. To produce algae, pipes or hoses are probably the best system. The individual pipe is small and very little structural mass is needed for pressure.

I have seen setups for algae growth at the Uni where my daughter studied.
I don't really care about the method, i just want to know if I should surround any mid sized base with a sea of green pipes.  I don't see anybody but spaceX having to deal with the configuration of a large Martian base.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 02/09/2017 11:57 pm
Try this
Quorn (https://en.wikipedia.org/wiki/Quorn#Production)
Still needs glucose.
So it's just an intermediate step and we still need the sunlight and some form of surface enclosure?  Or a nuclear reactor that makes light, which pretty much boils down to the same thing?  I'm just trying to find out if I need to surround the illustration of  my Mars base with km2 of greenery, either is soft of rigid domes, or if there is another way.

I think surrounding the base with greenery could well be a good way to go. You could grow all sorts in the domes, including  the raw materials for more domes by making them out of bioplastic (https://en.wikipedia.org/wiki/Bioplastic). I'm thinking completely automated processes producing raw materials with very little human input.

More traditional food could be grown in tunnels, as has just been started to be done in london, http://growing-underground.com/
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/10/2017 12:29 am
Oh and if you are tessellating domes hexagonal packing is much more area efficient.
Ok, here you go,  hexagonal pattern domes :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/10/2017 07:36 am
Nissen hut structures would be more material effective than domes for greenhouses to grow vegetables and fruit. For algae it would be pipes. Yes, a lot of green around the base. I can not yet believe that solar panels and LED light will be more effective. Maybe augmentation to natural light during some growth phase.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 02/11/2017 02:03 am
While not really in the "Amazing" category, what about a cylindrical shaped poly-something envelope held inside a similarly shaped net ?  Think of a salami or bratwurst sausage with that thin plastic net around it.  The tube would be fixed to rigid/semi-rigid end caps containing air locks, services, walkways to adjacent structures etc.
The net provides the majority of the tensile strength and needs minimal tying down.

If a cylindrical cross section is not optimal then adjusting the location and number of tie down points on the net would cause the shape to be more semi cylindrical.  Dig an appropriately shaped depression in the ground, put down some insulating layer, construct/install anchor points, locate the unit and add atmosphere to the required pressure.

Relatively simple with minimal rigid structural components.  The same general idea could be used to cover a small crater or fissure or chasma.

Workable ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/11/2017 11:05 am
Earthmoving equipment needs traction to counter inertia, which means it needs down-force, which means it needs weight.
"Light" earthmoving equipment on Mars is probably bad at moving earth.
That's not entirely correct.  Most earth moving for construction is not done by taking large bites of earth.

Not sure where you saw me say that it was.

The drive mechanism also matters.  A backhoe uses levered anchors, and then moves itself forward and anchors again if it's doing heavy digging. The weight of the machine itself hardly matters.

The stabiliser legs are simply fulcrum points. The counter-weight to the digging arm is the mass of the vehicle behind the legs. (During the initial down-cut, the most forward part of the vehicle is the fulcrum, either the front wheels or more typically a loader bucket. During the scoop-cut, the traction of the vehicle matters. During the lift and dump, the stabilisers are the fulcrum. In all three motions, the weight of the vehicle matters.)

Same with a grader. The wheel/track traction must overcome the resistance of the blade/ground interaction, the latter is unchanged on Mars, the former is much less.

Same with a dump truck or any transport. The traction must overcome the vehicle inertia, the latter depends on mass, the former on weight.

Etc/
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/11/2017 06:44 pm
Thought some of you might find this interesting.
It shows many of the similarities between a mining operation and an underground Mars colony.
I swear I had nose seen it before making my little Mars colony flyover video a few weeks ago!

https://www.youtube.com/watch?v=bqDbuZPwBrs
Title: Re: Envisioning Amazing Martian Habitats
Post by: Triptych on 02/17/2017 04:38 pm
I'm doing a bit of research for an upcoming book  ;) so I have a question:

How vulnerable would a geodesic dome be against asteroid/ man made impacts?

I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?

How would you repair such damage?

What would be a defense against such things?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 02/17/2017 06:01 pm
I'm doing a bit of research for an upcoming book  ;) so I have a question:

How vulnerable would a geodesic dome be against asteroid/ man made impacts?

I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?

How would you repair such damage?

What would be a defense against such things?

Since "of course it would be vulnerable" no matter how much effort is invested in protecting any single dome, the question "what would be a defense against such things" would probably profit from being widened to "what overall architecture would be the best defense against such things". A good answer would almost certainly involve not putting all eggs in one basket/dome. So more & smaller domes, interconnected by bulwarked underground tunnels, would be safer than fewer & larger domes interconnected by overground passageways.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/18/2017 02:10 am
I'm doing a bit of research for an upcoming book  ;) so I have a question:

How vulnerable would a geodesic dome be against asteroid/ man made impacts?

I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?

How would you repair such damage?

What would be a defense against such things?
For asteroids, orbital defense should be easy by the time we get to Mars.  Mars may have a lot of hardware in orbit as well, stations, fuel depots, solar cargoes, perhaps a mining operation on Phobos.

Against very velocity rocks, thrown by a mass driver, for example, there wouldn't be much that could be done.

One problem would be acoustic shock, that depending on the size of the impact could be deadly.  Then depressurization.

I expect for small punctures up to a few m wide you could have emergency balloons, that would home in on the hole and block it; rather like platelets in the blood stream home in on a wound and stop the blood flow.

you might also have a series of tracks built into the dome wall, and a robot arm, that moves in on a hole and fits some kinds of strong tarp over the hole.  A large dome has quite a bit of volume of air.   If you need, I can find my spreadsheet for holes in domes and spacecraft and send it your way.  Very handy in estimating the time your characters have to react!

You can scale your catastrophe using the kinetic energy equation

energy=1/2mass*velocity2.
The best way to get a feeling for it is to try a few well identified things, aircraft crashing, car crashing, etc, the scale it up to whatever you need.
For example, a 10 ton truck at 50 km per hour (14 m/s) = 14x14x10000/2= 980 000 kJ.  If you want to use a small rock at 0,1% of the speed of light, for a nice extreme, your rock will be 980 000*2 / 300000 * 300000= 2e-5 kg, or 0,02 grams.  A grain of sand.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 02/18/2017 02:25 am
I'm doing a bit of research for an upcoming book  ;) so I have a question:

How vulnerable would a geodesic dome be against asteroid/ man made impacts?

I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?

How would you repair such damage?

What would be a defense against such things?
For asteroids, orbital defense should be easy by the time we get to Mars.  Mars may have a lot of hardware in orbit as well, stations, fuel depots, solar cargoes, perhaps a mining operation on Phobos.

Against very velocity rocks, thrown by a mass driver, for example, there wouldn't be much that could be done.

One problem would be acoustic shock, that depending on the size of the impact could be deadly.  Then depressurization.

I expect for small punctures up to a few m wide you could have emergency balloons, that would home in on the hole and block it; rather like platelets in the blood stream home in on a wound and stop the blood flow.

you might also have a series of tracks built into the dome wall, and a robot arm, that moves in on a hole and fits some kinds of strong tarp over the hole.  A large dome has quite a bit of volume of air.   If you need, I can find my spreadsheet for holes in domes and spacecraft and send it your way.  Very handy in estimating the time your characters have to react!

You can scale your catastrophe using the kinetic energy equation

energy=1/2mass*velocity2.
The best way to get a feeling for it is to try a few well identified things, aircraft crashing, car crashing, etc, the scale it up to whatever you need.
For example, a 10 ton truck at 50 km per hour (14 m/s) = 14x14x10000/2= 980 000 kJ.  If you want to use a small rock at 0,1% of the speed of light, for a nice extreme, your rock will be 980 000*2 / 300000 * 300000= 2e-5 kg, or 0,02 grams.  A grain of sand.

Mars' atmosphere limits all but very large meteorites to speeds somewhere around the speed of sound. Your grain of sand would vaporize, and even 1 kg-ish chunks of a larger breakup reaching the ground probably wouldn't cause any serious damage. Visible impact craters on Mars are all caused by impacts that are definitely large enough to be catastrophic, but they are quite rare even on geologic timescales and exceedingly unlikely on human timescales.

There is the off chance of a meteorite massing a few tens to a few thousand kg hitting a dome at around the speed of sound, with very serious but not necessary catastrophic effects. I think it's unlikely, but if there enough domes on Mars it will happen eventually.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/18/2017 04:34 am
The dome is likely to be large, so it will most likely contain buildings inside that people will spend most of their time in. So make the interior buildings capable of being at least minimally pressurized (2-3psi, say, enough if you're breathing pure oxygen from a mask... Or more like 4-5psi to enhance survivability until you get your oxygen mask on). Places far from building air locks would have emergency pressure bags, like Gamow bags used for high altitude treatment of altitude sickness. Might add arms or legs to them for mobility.

Also, possibly a device worn near the neck that can inject oxygenated blood to keep the brain alive for a few minutes.

You should have a couple minutes to get to shelter if the dome is large. Perhaps a drone could fly up and cover the hole with a big balloon to at least slow the leakage.

Also, large reservoirs of air could help maintain pressure in emergency. Also, large compressors could bring in Martian air to like 1psi, maybe enough to keep the plants alive and reduce embolism.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/18/2017 12:24 pm
All that needs to be done is to bulldoze the dirt until solid rock is reached, then erect walls/roof, and with more bulldozing pile up regolith on/around them.

"All that needs to be done"...  :-)

Why would you want to bulldoze away a lot of dirt to reach solid rock if you can easily drive up to any rockface at the bottom of any hill?

Why would you want to transport wall and roof building material all the way from Earth if you can dig a tunnel and thereby get solid walls and "roofs" from abundant on-site material?

Of course, I don't propose to transport building materials from Earth. Being able to make Marscrete is a must.

Why not tunnels? I like tunnels and already advocated looking into making them on Mars, but I suspect tunnelling may turn out to be much less efficient. In which case, this is my alternative idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/18/2017 02:28 pm
I'm doing a bit of research for an upcoming book  ;) so I have a question:
How vulnerable would a geodesic dome be against asteroid/ man made impacts?
I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?
How would you repair such damage?
What would be a defense against such things?

The only defense is to not be on the surface.

However, a geodesic dome is made of panels, so you're likely to lose just one panel in an impact.

[I was playing around with Bernoulli's equation for fluid flow (Poiseuille's doesn't work for low viscosity and large hole-diameter/wall-thickness ratio.) I'm not sure if I've got it right, but the result I get is that a 1m diameter hole (one panel) in a 100m dome would see the pressure drop from 10psi to 2psi (breathing pure oxygen) in just under 3 minutes. Hopefully enough time to reach a pressurisable shelter. OTOH, a 4 inch hole would take 4 freakin' hours to reach 2psi. It'd take half an hour for your ears to "pop".]
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/18/2017 02:30 pm
Using GoSpaceX's very good comment (I forgot about the atmosphere!) and using as an analog a terrorist attack or a small industrial explosion involving the equivalent of 10 kg of explosives: 41 840 000 joules (1 ton of tnt = 4,184e9 joules)

If the terminal velocity of the rock is mach2 or 680 m/s then 41 840 0000*2/680^2=232 kg.  That's a really big rock!  A rock this size is extremely unlikely and probably fits in the large asteroid category, so perhaps it would be going faster than mach 2.  At mach 10, you have a 2,32 kg rock, perhaps nickel iron?
The probability for this is probably very close to 0. 
And faking it, by creating a fake asteroid is probably impossible as well, since there are too many variables in the martian atmosphere, and a tiny difference in density, from the time of day, or in the shape of the rock, would have it land harmlessly far from the dome.
So a Martian dome can be considered for planning purposes to be safe from meteorite impact.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/18/2017 02:59 pm
I'm doing a bit of research for an upcoming book  ;) so I have a question:
How vulnerable would a geodesic dome be against asteroid/ man made impacts?
I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?
How would you repair such damage?
What would be a defense against such things?

The only defense is to not be on the surface.

However, a geodesic dome is made of panels, so you're likely to lose just one panel in an impact.

[I was playing around with Bernoulli's equation for fluid flow (Poiseuille's doesn't work for low viscosity and large hole-diameter/wall-thickness ratio.) I'm not sure if I've got it right, but the result I get is that a 1m diameter hole (one panel) in a 100m dome would see the pressure drop from 10psi to 2psi (breathing pure oxygen) in just under 3 minutes. Hopefully enough time to reach a pressurisable shelter. OTOH, a 4 inch hole would take 4 freakin' hours to reach 2psi. It'd take half an hour for your ears to "pop".]
Hi, I used a different equation taken from an engineering website, that has an even slower leak rate.  It is based on the choked flow proposition that the flow cannot be faster than the speed of sound in the gas.
I have no idea what is correct, but it does seem it will take some time.  I get 12 psi after 4 min and 2 psi after about 40 min. 
See spreadsheet.  Inputs in green fields, calculation in white fields.  Metric units so use a comma and not a period!

Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/18/2017 05:49 pm
I'm doing a bit of research for an upcoming book  ;) so I have a question:
How vulnerable would a geodesic dome be against asteroid/ man made impacts?
I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?
How would you repair such damage?
What would be a defense against such things?

The only defense is to not be on the surface.

However, a geodesic dome is made of panels, so you're likely to lose just one panel in an impact.

[I was playing around with Bernoulli's equation for fluid flow (Poiseuille's doesn't work for low viscosity and large hole-diameter/wall-thickness ratio.) I'm not sure if I've got it right, but the result I get is that a 1m diameter hole (one panel) in a 100m dome would see the pressure drop from 10psi to 2psi (breathing pure oxygen) in just under 3 minutes. Hopefully enough time to reach a pressurisable shelter. OTOH, a 4 inch hole would take 4 freakin' hours to reach 2psi. It'd take half an hour for your ears to "pop".]
Hi, I used a different equation taken from an engineering website, that has an even slower leak rate.  It is based on the choked flow proposition that the flow cannot be faster than the speed of sound in the gas.
I have no idea what is correct, but it does seem it will take some time.  I get 12 psi after 4 min and 2 psi after about 40 min. 
See spreadsheet.  Inputs in green fields, calculation in white fields.  Metric units so use a comma and not a period!

A 100m diameter dome isn't big enough for a football pitch. Even only three minutes is a lot of time to get to shelter. With 40 minutes, you might wait to get a better look at the emergency repairs before heading to shelter.

Imagine how far you can run in three minutes under Mars low gravity.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 02/18/2017 05:57 pm
I'm doing a bit of research for an upcoming book  ;) so I have a question:
How vulnerable would a geodesic dome be against asteroid/ man made impacts?
I mean, of course it would be vulnerable, but how much damage could one take before it turns catastrophic?
How would you repair such damage?
What would be a defense against such things?

The only defense is to not be on the surface.

However, a geodesic dome is made of panels, so you're likely to lose just one panel in an impact.

[I was playing around with Bernoulli's equation for fluid flow (Poiseuille's doesn't work for low viscosity and large hole-diameter/wall-thickness ratio.) I'm not sure if I've got it right, but the result I get is that a 1m diameter hole (one panel) in a 100m dome would see the pressure drop from 10psi to 2psi (breathing pure oxygen) in just under 3 minutes. Hopefully enough time to reach a pressurisable shelter. OTOH, a 4 inch hole would take 4 freakin' hours to reach 2psi. It'd take half an hour for your ears to "pop".]

You cannot get half the air volume of a 100m diameter dome out of a 1m diameter hole in less than 8 minutes, even at constant 1 atm pressure... the flow is sonicly choked in the hole to ~270 m3/sec.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/18/2017 07:00 pm
I suspect that a big dome will be seen as a "luxury item" for the first many years on Mars. If just for the view then a "Cupola"-sized dome will do just fine. Maybe a couple. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/18/2017 07:03 pm

Of course, I don't propose to transport building materials from Earth. Being able to make Marscrete is a must.

Why not tunnels? I like tunnels and already advocated looking into making them on Mars, but I suspect tunnelling may turn out to be much less efficient. In which case, this is my alternative idea.

So it seems that each choice comes with its own technical challenge. Tunnelling or making in-situ concrete. I don't know which  one is the easiest, but I suspect that both will actually be necessary to ensure a big expansion potential for a base.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/18/2017 08:30 pm
I suspect that a big dome will be seen as a "luxury item" for the first many years on Mars. If just for the view then a "Cupola"-sized dome will do just fine. Maybe a couple.
A medium-sized dome (or part of one) will be part of the very first crewed mission to Mars. ITS itself has a third of a 10-12m diameter dome as part of its habitable section and will be used for initial habitation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/18/2017 10:05 pm
I suspect that a big dome will be seen as a "luxury item" for the first many years on Mars. If just for the view then a "Cupola"-sized dome will do just fine. Maybe a couple.
A medium-sized dome (or part of one) will be part of the very first crewed mission to Mars. ITS itself has a third of a 10-12m diameter dome as part of its habitable section and will be used for initial habitation.

Geodesic dome brought the panorama window of ITS to my thoughts immediately. I too expect a dome of at least 15m diameter if not on the first then on the second synod with a manned lander. I think Elon Musk will see it as indispensable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/18/2017 10:18 pm

Of course, I don't propose to transport building materials from Earth. Being able to make Marscrete is a must.

Why not tunnels? I like tunnels and already advocated looking into making them on Mars, but I suspect tunnelling may turn out to be much less efficient. In which case, this is my alternative idea.

So it seems that each choice comes with its own technical challenge. Tunnelling or making in-situ concrete. I don't know which  one is the easiest, but I suspect that both will actually be necessary to ensure a big expansion potential for a base.

Making concrete and many other construction materials will be necessary anyway, even with tunnels. Tunnel walls need grouting (they will inevitably have cracks or unstable rocks); in big tunnels/caverns you'd want to build internal walls.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 02/18/2017 10:48 pm
You don't need concrete for internal walls if they're not load bearing. Stud walls are the internal wall of choice by the construction industry on Earth. Materials might be lacking for that on Mars at first, but dry stone walls have been successfully used on Earth for thousands of years. With lower gravity dry stone walls would be even more practical on Mars.

Example of dry stone wall from Machu Picchu, Peru, still standing after 600-700 years;

(http://i.imgur.com/hDCCnoB.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/19/2017 12:47 am
I suspect that a big dome will be seen as a "luxury item" for the first many years on Mars. If just for the view then a "Cupola"-sized dome will do just fine. Maybe a couple.
A medium-sized dome (or part of one) will be part of the very first crewed mission to Mars. ITS itself has a third of a 10-12m diameter dome as part of its habitable section and will be used for initial habitation.

Geodesic dome brought the panorama window of ITS to my thoughts immediately. I too expect a dome of at least 15m diameter if not on the first then on the second synod with a manned lander. I think Elon Musk will see it as indispensable.
Got that covered in the model  :-)  Guess eventually it was converted into a garage when better installations were built!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/19/2017 02:25 am
I've had a little bit of fun adding a grandiose entrance to the base.

First view of Mars from inside the ITS.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 02/19/2017 11:14 am
I suspect that a big dome will be seen as a "luxury item" for the first many years on Mars. If just for the view then a "Cupola"-sized dome will do just fine. Maybe a couple.
A medium-sized dome (or part of one) will be part of the very first crewed mission to Mars. ITS itself has a third of a 10-12m diameter dome as part of its habitable section and will be used for initial habitation.

Geodesic dome brought the panorama window of ITS to my thoughts immediately. I too expect a dome of at least 15m diameter if not on the first then on the second synod with a manned lander. I think Elon Musk will see it as indispensable.

Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

[Edit: Love the grandiose entrance, I think it is super important. You can't have a sprawling undergound habitat accessed by a small-looking entrance, it looks and feels jarringly wrong]
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/19/2017 03:07 pm
You don't need concrete for internal walls if they're not load bearing. Stud walls are the internal wall of choice by the construction industry on Earth.

Not on Earth, just in US. In Europe, for example, internal walls are usually more solid. Mine are from concrete. Other people have gypsum walls, brick walls, etc.

More importantly, I said "making concrete *and many other construction materials*". I have no fixation on the concrete per se. My point is that construction materials must be produced on Mars early on. As opposed, for example, to computer chips, scientific instruments, reactors etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/19/2017 03:09 pm
Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

Unsubstantiated. In what way a window is better than a large TV screen connected to a set of external visible light and IR cameras? I can see only drawbacks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 02/19/2017 03:10 pm
Concrete will be tricky on mars, no limestone.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/19/2017 03:22 pm
Concrete will be tricky on mars, no limestone.

It could be marscrete. A material made from local resources, not limestone. It needs less energy to produce, too.The material is even better than normal concrete except it is not very resistant to water. Not a concern on Mars.

https://www.youtube.com/watch?v=PmC3NZoiMzQ
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/19/2017 04:20 pm
Concrete will be tricky on mars, no limestone.

It could be marscrete. A material made from local resources, not limestone. It needs less energy to produce, too.The material is even better than normal concrete except it is not very resistant to water. Not a concern on Mars.

https://www.youtube.com/watch?v=PmC3NZoiMzQ
How will it react to the humidity in the habitats?  Humidity eats greenhouses on Earth, so it'll gobble this stuff up.
I guess a vapor barrier should solve that though.  Would be a good idea anyway, even if we did use portland cement, it doesn't like humidity all that much either, but it's more a problem over centuries.  So Marscrete, a vapor barrier and some kind of locally produced facing material.  Wood would be nice, eventually, some kind of painted fiberboard,
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/19/2017 05:18 pm
Basalt fiber and materials made from it might be interesting to look at. They have widely varying properties. Some are remarkably wood-like.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 02/19/2017 05:19 pm
You don't need concrete for internal walls if they're not load bearing. Stud walls are the internal wall of choice by the construction industry on Earth.

Not on Earth, just in US. In Europe, for example, internal walls are usually more solid. Mine are from concrete. Other people have gypsum walls, brick walls, etc.

More importantly, I said "making concrete *and many other construction materials*". I have no fixation on the concrete per se. My point is that construction materials must be produced on Mars early on. As opposed, for example, to computer chips, scientific instruments, reactors etc.

It varies by time and region, and I'm sure is different across Europe. I'm more knowledgable about UK building practices than US. Most modern UK houses are built really cheaply, in the past they used stone, bricks, aerated concrete blocks, but now stud walls are the norm. Obviously load bearing walls are still made from concrete blocks. Anyway, the point was that assuming that internal walls aren't load bearing, then they could be made from anything. They could even just be curtains, or "rooms" could be tents. One thing that Mars has a lot of is rock, so that would likely be the construction material of choice.

I think that two important construction materials would be a sealant paint to seal the excavated spaces, and insulation to surround it. I'm not sure what local resources would be best for those.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/19/2017 05:27 pm
Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

Unsubstantiated. In what way a window is better than a large TV screen connected to a set of external visible light and IR cameras? I can see only drawbacks.
Its an endless debate, with no clear solution.  Astronauts in the ISS like to look at the Earth directly.  They could look at screens, but they don't, as far as I know.
There is much more light in a window, and true depth of field.  You may not need to look out of them all the time, but having access from time to time seems like a good idea.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/19/2017 05:37 pm
Concrete will be tricky on mars, no limestone.

It could be marscrete. A material made from local resources, not limestone. It needs less energy to produce, too.The material is even better than normal concrete except it is not very resistant to water. Not a concern on Mars.

https://www.youtube.com/watch?v=PmC3NZoiMzQ
How will it react to the humidity in the habitats?  Humidity eats greenhouses on Earth, so it'll gobble this stuff up.
I guess a vapor barrier should solve that though.  Would be a good idea anyway, even if we did use portland cement, it doesn't like humidity all that much either, but it's more a problem over centuries.  So Marscrete, a vapor barrier and some kind of locally produced facing material.  Wood would be nice, eventually, some kind of painted fiberboard,

My understanding was that it is not that sensitive. But more importantly a coating would be needed to minimize air loss. I think if any paneling happens the panels should be easily removable. Cleaning to limit mold and bacterial growth will very much be needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 02/19/2017 06:05 pm
Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

Unsubstantiated. In what way a window is better than a large TV screen connected to a set of external visible light and IR cameras? I can see only drawbacks.
Its an endless debate, with no clear solution.  Astronauts in the ISS like to look at the Earth directly.  They could look at screens, but they don't, as far as I know.
There is much more light in a window, and true depth of field.  You may not need to look out of them all the time, but having access from time to time seems like a good idea.

Yeah, there is no clear solution because the preference is personal and subjective. To reveal the average preference, maybe we can look at homes in very harsh climates on Earth? What fraction of those homes doesn't have a single window to let sunlight in?

I think the answer from such investigations should confirm the common sense that most people, if given the choice, would prefer to have a direct connection to real sunlight, as opposed to merely photons of light.

Yes, underground can be made potentially far more robust and healthy than a surface dome, I've been thinking about that from the first day after the ITS reveal. But trying to weigh appeal vs. safety kinda misses the point. The point at this phase is marketing the concept of Mars as a place where one can imagine oneself living. Can anyone imagine themselves living the rest of your lives in a tunnel with no windows?

With this kind of reasoning, my best guess is that a balanced design for a Mars habitat would mix and match underground, overground, dome, window and skylight elements. Plus many artificial lighting/imaging solutions of course as complements. But I find it hard to believe that the artificial stuff can or will completely replace real sunlight.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 02/19/2017 10:19 pm
Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

Unsubstantiated. In what way a window is better than a large TV screen connected to a set of external visible light and IR cameras? I can see only drawbacks.
Its an endless debate, with no clear solution.  Astronauts in the ISS like to look at the Earth directly.  They could look at screens, but they don't, as far as I know.
There is much more light in a window, and true depth of field.  You may not need to look out of them all the time, but having access from time to time seems like a good idea.

Yeah, there is no clear solution because the preference is personal and subjective. To reveal the average preference, maybe we can look at homes in very harsh climates on Earth? What fraction of those homes doesn't have a single window to let sunlight in?

I think the answer from such investigations should confirm the common sense that most people, if given the choice, would prefer to have a direct connection to real sunlight, as opposed to merely photons of light.

Yes, underground can be made potentially far more robust and healthy than a surface dome, I've been thinking about that from the first day after the ITS reveal. But trying to weigh appeal vs. safety kinda misses the point. The point at this phase is marketing the concept of Mars as a place where one can imagine oneself living. Can anyone imagine themselves living the rest of your lives in a tunnel with no windows?

With this kind of reasoning, my best guess is that a balanced design for a Mars habitat would mix and match underground, overground, dome, window and skylight elements. Plus many artificial lighting/imaging solutions of course as complements. But I find it hard to believe that the artificial stuff can or will completely replace real sunlight.

Again: I would use shafts, not tunnels. Dig vertically down, put a dome with glass on the top and then use mirrors (plastic with an aluminum layer) to mirror down sunlight. Use spiral stairs to get around and use terraces and dug in horizontal rooms for living, workshops and storage. This way you get natural light, long lines of sight, you get natural exercise while moving around (walking in low gravity is difficult anyway) and you have a kind of 3D plaza as the central part of your "city". You can then also have plants on the walls, vines and others. And of course a natural day/night cycle with daylight in the open spaces.

Just as living (and walking) in tunnels isn't exactly cozy, having to strap yourself two hours a day to exercising machines isn't going to be fun. Climbing 100m up and down several times a day gives lots of exercise even without lots of self-discipline. And you have some open space to look around and see others instead of living like moles in tunnels.

Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/19/2017 10:32 pm
Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

Unsubstantiated. In what way a window is better than a large TV screen connected to a set of external visible light and IR cameras? I can see only drawbacks.
Its an endless debate, with no clear solution.  Astronauts in the ISS like to look at the Earth directly.  They could look at screens, but they don't, as far as I know.
There is much more light in a window, and true depth of field.  You may not need to look out of them all the time, but having access from time to time seems like a good idea.

Yeah, there is no clear solution because the preference is personal and subjective. To reveal the average preference, maybe we can look at homes in very harsh climates on Earth? What fraction of those homes doesn't have a single window to let sunlight in?

I think the answer from such investigations should confirm the common sense that most people, if given the choice, would prefer to have a direct connection to real sunlight, as opposed to merely photons of light.

Yes, underground can be made potentially far more robust and healthy than a surface dome, I've been thinking about that from the first day after the ITS reveal. But trying to weigh appeal vs. safety kinda misses the point. The point at this phase is marketing the concept of Mars as a place where one can imagine oneself living. Can anyone imagine themselves living the rest of your lives in a tunnel with no windows?

With this kind of reasoning, my best guess is that a balanced design for a Mars habitat would mix and match underground, overground, dome, window and skylight elements. Plus many artificial lighting/imaging solutions of course as complements. But I find it hard to believe that the artificial stuff can or will completely replace real sunlight.

A balanced design makes sense. It's not practical to have windows in most rooms. Monitors will have to do in most cases, and they'll brighten up work and living spaces, but there will still be some windows, cupolas, domes, etc.

The human eye is far more capable than any camera. While looking at a 4K screen might suffice in some cases, it is not a replacement for looking out a window. If anyone doubts me, look at a monitor and then go look out a window. If you can't tell the difference, it's because you have bad eyesight. People on Mars with good eyesight will want to look out a window once in awhile.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/19/2017 10:46 pm
A medium-sized dome (or part of one) will be part of the very first crewed mission to Mars. ITS itself has a third of a 10-12m diameter dome as part of its habitable section and will be used for initial habitation.

For the LEM they also wanted huge windows. They ended up with something much smaller. My guess is that the ITS will go in the same direction, even though I hope it won't be the case.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/19/2017 10:56 pm
Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

Unsubstantiated. In what way a window is better than a large TV screen connected to a set of external visible light and IR cameras? I can see only drawbacks.
Its an endless debate, with no clear solution.  Astronauts in the ISS like to look at the Earth directly.  They could look at screens, but they don't, as far as I know.

Your argument is based on what you don't know (whether they use screens and cameras to look outside, and how much they (dis)like it). Interesting concept.

Quote
There is much more light in a window, and true depth of field.  You may not need to look out of them all the time, but having access from time to time seems like a good idea.

"Seems like a good idea" needs to be weighted against other considerations. Such as cost, additional materials production (glass, transparent plastics), structural weakness, added requirement that habitat is not buried under meters of regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/19/2017 11:00 pm
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 02/19/2017 11:02 pm
Dynamic range of the human eye is very large. No idea if it is better than all cameras though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/19/2017 11:13 pm
Example photo. When you enter this gloomy, windowless cavern, you just want to kill yourself, right?
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/20/2017 12:29 am
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.

Wrong. You're comparing apples and oranges. In visible wavelengths the eye sees more detail and has a greater dynamic range than a video camera. A 4K display isn't a replacement for using your eye looking out a window.
Title: Re: Envisioning Amazing Martian Habitats
Post by: abc2010x on 02/20/2017 07:28 am
How big (voluminous) could an underground habitat on Mars be made? Wouldn't a large enough underground cavern be OK. I keep thinking of the old 1970's spin gravity habitat artistry. Or more recently in the film Elysium (although I haven't seen it)

http://4.bp.blogspot.com/-rM1DRiHvMHg/Vb3sQ3sNWaI/AAAAAAAAEGI/sDOROnyHV4o/s1600/Elysium-wallpapers-10.jpg (http://4.bp.blogspot.com/-rM1DRiHvMHg/Vb3sQ3sNWaI/AAAAAAAAEGI/sDOROnyHV4o/s1600/Elysium-wallpapers-10.jpg)

http://99percentinvisible.org/app/uploads/2016/06/space-colony-series.jpg (http://99percentinvisible.org/app/uploads/2016/06/space-colony-series.jpg)

If you have a large enough cavern, could you also have a sky blue ceiling projected far overhead? I don't think it would have to be very far away for the eye to perceive it focused on infinity.

Unfortunately I am no artist, but I think a large Mars cavern with lots of greenery might not be too bad.

The idea of living life in a spin gravity space city seems OK but the idea of doing so in an underground cavern not so. In one case you have solid rock beyond the walls; in the other you have hard vacuum. What's the difference?
Title: Re: Envisioning Amazing Martian Habitats
Post by: abc2010x on 02/20/2017 07:54 am
I would like a place on the surface where I could look through the windows at the bright unblinking stars and appreciate the vastness.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/20/2017 02:38 pm
Agreed, it will be hard to create demand for moving to Mars if all you have to offer is tunnels or homes covered by mounds of regolith. You need to be able to offer domes and windows, too.

Unsubstantiated. In what way a window is better than a large TV screen connected to a set of external visible light and IR cameras? I can see only drawbacks.
Its an endless debate, with no clear solution.  Astronauts in the ISS like to look at the Earth directly.  They could look at screens, but they don't, as far as I know.
There is much more light in a window, and true depth of field.  You may not need to look out of them all the time, but having access from time to time seems like a good idea.

Yeah, there is no clear solution because the preference is personal and subjective. To reveal the average preference, maybe we can look at homes in very harsh climates on Earth? What fraction of those homes doesn't have a single window to let sunlight in?

I think the answer from such investigations should confirm the common sense that most people, if given the choice, would prefer to have a direct connection to real sunlight, as opposed to merely photons of light.

Yes, underground can be made potentially far more robust and healthy than a surface dome, I've been thinking about that from the first day after the ITS reveal. But trying to weigh appeal vs. safety kinda misses the point. The point at this phase is marketing the concept of Mars as a place where one can imagine oneself living. Can anyone imagine themselves living the rest of your lives in a tunnel with no windows?

With this kind of reasoning, my best guess is that a balanced design for a Mars habitat would mix and match underground, overground, dome, window and skylight elements. Plus many artificial lighting/imaging solutions of course as complements. But I find it hard to believe that the artificial stuff can or will completely replace real sunlight.

Again: I would use shafts, not tunnels. Dig vertically down, put a dome with glass on the top and then use mirrors (plastic with an aluminum layer) to mirror down sunlight. Use spiral stairs to get around and use terraces and dug in horizontal rooms for living, workshops and storage. This way you get natural light, long lines of sight, you get natural exercise while moving around (walking in low gravity is difficult anyway) and you have a kind of 3D plaza as the central part of your "city". You can then also have plants on the walls, vines and others. And of course a natural day/night cycle with daylight in the open spaces.

Just as living (and walking) in tunnels isn't exactly cozy, having to strap yourself two hours a day to exercising machines isn't going to be fun. Climbing 100m up and down several times a day gives lots of exercise even without lots of self-discipline. And you have some open space to look around and see others instead of living like moles in tunnels.
...an excellent addition perfectly in the spirit of this thread! I'd like to see a rendering of it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 02/21/2017 12:54 pm
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.

Wrong. You're comparing apples and oranges. In visible wavelengths the eye sees more detail and has a greater dynamic range than a video camera. A 4K display isn't a replacement for using your eye looking out a window.

Commercial cameras, yes, although even the cheaper end are getting very good. However, you can buy/build cameras that are exceptionally good, it's just you don't need expensive cameras for your phone or video camera. 16 bit colour per channel would be fine (and even now most camera sensors are at least 10 bit).

The slightly more difficult bit is a high dynamic range display, but even they are getting better and better every day. Many displays are only 6bit/channel which is why you see blocking in dark scenes, but a decent (ie expensive) professional display will be 8 or even 10 bits per channel, which should be good enough for the purposes here.

You will also need a high bandwidth connection from camera to display, and decent 10 or more bit compression.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 02/21/2017 01:35 pm
Concrete will be tricky on mars, no limestone.

It could be marscrete. A material made from local resources, not limestone. It needs less energy to produce, too.The material is even better than normal concrete except it is not very resistant to water. Not a concern on Mars.

https://www.youtube.com/watch?v=PmC3NZoiMzQ
How will it react to the humidity in the habitats?  Humidity eats greenhouses on Earth, so it'll gobble this stuff up.
I guess a vapor barrier should solve that though.  Would be a good idea anyway, even if we did use portland cement, it doesn't like humidity all that much either, but it's more a problem over centuries.  So Marscrete, a vapor barrier and some kind of locally produced facing material.  Wood would be nice, eventually, some kind of painted fiberboard,

Porcelana concrete would be a possible option, as there are ready sources of volcanic glass type rock, however, what you'd substitute limestone and water with currently escapes me.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/21/2017 03:08 pm
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.

Wrong. You're comparing apples and oranges. In visible wavelengths the eye sees more detail

Of course not. Depends on the camera. Eye may see more detail than a *crappy camera*.

But if you need/want, you can always buy a camera which is orders of magnitude better than human eyesight in resolution, not to mention cameras which see in different parts of spectrum (IR would be very useful at night on Mars).

Did not somehow miss thousands of youtube videos from military helicopters' cameras? Why those even exist if "human eye is better"? Because military people are so stupid they order hardware they don't need, I take it? This makes no sense.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/21/2017 03:24 pm
Porcelana concrete would be a possible option, as there are ready sources of volcanic glass type rock, however, what you'd substitute limestone and water with currently escapes me.

Concrete-type material based on oxide reactions with water is far from the only material possible. Epoxy resins with sand/rock aggregate is an option. Various polyurethane and polyester-based liquids also. They are not normally used on Earth for higher-volume work because they are far more expensive than concrete. Costs of producing them on Mars may be different.

https://en.wikipedia.org/wiki/Engineered_stone
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/21/2017 03:53 pm
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.

Wrong. You're comparing apples and oranges. In visible wavelengths the eye sees more detail

Of course not. Depends on the camera. Eye may see more detail than a *crappy camera*.

But if you need/want, you can always buy a camera which is orders of magnitude better than human eyesight in resolution, not to mention cameras which see in different parts of spectrum (IR would be very useful at night on Mars).

Did not somehow miss thousands of youtube videos from military helicopters' cameras? Why those even exist if "human eye is better"? Because military people are so stupid they order hardware they don't need, I take it? This makes no sense.

We're discussing using a camera and monitor to replicate looking out a window for psychological reasons. I don't understand why you keep going on about IR and military grade systems. You're the one not making sense.

Commercial cameras, yes, although even the cheaper end are getting very good. However, you can buy/build cameras that are exceptionally good, it's just you don't need expensive cameras for your phone or video camera. 16 bit colour per channel would be fine (and even now most camera sensors are at least 10 bit).

The slightly more difficult bit is a high dynamic range display, but even they are getting better and better every day. Many displays are only 6bit/channel which is why you see blocking in dark scenes, but a decent (ie expensive) professional display will be 8 or even 10 bits per channel, which should be good enough for the purposes here.

You will also need a high bandwidth connection from camera to display, and decent 10 or more bit compression.

While high quality cameras and monitors would be sufficient in some areas of an underground base, it would be nice to go up to an observation dome to look around. The high quality display will still not be able to replicate your natural stereoscopic vision.

And before anyone says you can wear 3D glasses, just don't.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 02/22/2017 03:04 am
Quote
Again: I would use shafts, not tunnels.

Digging upward would make ridding the tailings easier.  In either case, up or down,  they would need to use equipment different than what has been suggested in the other thread.

Edit:  Creating the horizontal tunnels for surface or dome access would be a good place to remove the tailings to.  So, those could be created as the shaft progresses.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/22/2017 04:53 am
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.

Wrong. You're comparing apples and oranges. In visible wavelengths the eye sees more detail

Of course not. Depends on the camera. Eye may see more detail than a *crappy camera*.

But if you need/want, you can always buy a camera which is orders of magnitude better than human eyesight in resolution, not to mention cameras which see in different parts of spectrum (IR would be very useful at night on Mars).

Did not somehow miss thousands of youtube videos from military helicopters' cameras? Why those even exist if "human eye is better"? Because military people are so stupid they order hardware they don't need, I take it? This makes no sense.
Given the constraints, the human eye is highly optimized. It has a fairly small aperture, but is nearly diffraction limited (if you have excellent vision). Because it is foveated, you get a very high peak angular resolution in spite of the fact that there aren't THAT many "pixels" in the human eye while the field of view is enormous (if you replicated the field of view of our binocular vision with a non-foveated camera, it'd require about 122 megapixels, more than any DSLR you can buy today... plus the optics would be a real challenge, too). The stabilization is excellent. Built-in stereographic depth processing that works like a charm. Focal speed and accuracy is incredibly fluid. Focal range is excellent as well. Self-cleaning optics with built-in fast-reacting protective shutter. Dynamic range is nigh-unbeatable. Given time to adapt, the eye can detect light with only one photon (about 5 photons after you include our neural filtering), yet our eyes work in blaring sunlight as well. Slew rate and stability is also fantastic.

All of these things make for a very big challenge replicating for both the camera and the display. The only chance you'd have is something you strap to your face, which would be annoying. A flat panel can not replicate the experience and won't be able to for decades. But even the VR headset will need a decade and a half to start approaching the real limits of our vision with full fluidity (probably need at least 1000fps on the display-side, though not at the capture-side), and due to the necessity for optics in the VR headset and the introduction of artifacts, STILL would not be able to fully replicate the experience of looking at a starfield with one's own eyes (and I think getting truly to darksky starfield levels of dynamic range for the display while at those extreme resolutions and framerates will remain a challenge for decades...). Plus you have the sensation of a thing strapped to your face. And the knowledge that you're not looking at something real.

And if you insist on not having something strapped to your head, well, there might be a million people on Mars before a flat panel could fully replicate a full starfield at all angles and full fluidity and full dynamic range and without introducing detectable artifacts.

At some point, yeah, you might as well just put in a window. Also, maybe a spacesuit helmet sphere (and shoulders). Like poking your head into space while remaining in the comfort of the spaceship. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/22/2017 05:44 am
Also, maybe a spacesuit helmet sphere (and shoulders). Like poking your head into space while remaining in the comfort of the spaceship.

By the time you've optimised that design for being projected from a wall, you've ended up with a small cupola.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/22/2017 05:48 am
Also, maybe a spacesuit helmet sphere (and shoulders). Like poking your head into space while remaining in the comfort of the spaceship.

By the time you've optimised that design for being projected from a wall, you've ended up with a small cupola.
I was originally thinking of a big transparent sphere you could go into, then optimized it down to just a space helmet. :) probably a lot more realistic that way.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gospacex on 02/22/2017 09:55 am
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.

Wrong. You're comparing apples and oranges. In visible wavelengths the eye sees more detail

Of course not. Depends on the camera. Eye may see more detail than a *crappy camera*.

But if you need/want, you can always buy a camera which is orders of magnitude better than human eyesight in resolution, not to mention cameras which see in different parts of spectrum (IR would be very useful at night on Mars).

Did not somehow miss thousands of youtube videos from military helicopters' cameras? Why those even exist if "human eye is better"? Because military people are so stupid they order hardware they don't need, I take it? This makes no sense.

We're discussing using a camera and monitor to replicate looking out a window for psychological reasons.

Well, in this case 4K monitor works better for me than an actual window, since I have myopia and far off objects are blurred for me. Somehow I survive my inability to "fully" enjoy the view from the window, as do other ~30% of world population who are myopic.

Quote
I don't understand why you keep going on about IR and military grade systems.

For example, because on Mars, it'd be quite useful to be able to see people working outside of the base at night. If someone has an accident and needs help, say. You won't see that through the window at night, but will see it on TV screen showing camera view in IR mode.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 02/22/2017 10:18 am
The human eye is far more capable than any camera.

Of course, everyone knows this is false. There are IR and UV cameras. There are cameras with zoom which is better than eyesight of any human.

Wrong. You're comparing apples and oranges. In visible wavelengths the eye sees more detail

Of course not. Depends on the camera. Eye may see more detail than a *crappy camera*.

But if you need/want, you can always buy a camera which is orders of magnitude better than human eyesight in resolution, not to mention cameras which see in different parts of spectrum (IR would be very useful at night on Mars).

Did not somehow miss thousands of youtube videos from military helicopters' cameras? Why those even exist if "human eye is better"? Because military people are so stupid they order hardware they don't need, I take it? This makes no sense.

We're discussing using a camera and monitor to replicate looking out a window for psychological reasons. I don't understand why you keep going on about IR and military grade systems. You're the one not making sense.

Commercial cameras, yes, although even the cheaper end are getting very good. However, you can buy/build cameras that are exceptionally good, it's just you don't need expensive cameras for your phone or video camera. 16 bit colour per channel would be fine (and even now most camera sensors are at least 10 bit).

The slightly more difficult bit is a high dynamic range display, but even they are getting better and better every day. Many displays are only 6bit/channel which is why you see blocking in dark scenes, but a decent (ie expensive) professional display will be 8 or even 10 bits per channel, which should be good enough for the purposes here.

You will also need a high bandwidth connection from camera to display, and decent 10 or more bit compression.

While high quality cameras and monitors would be sufficient in some areas of an underground base, it would be nice to go up to an observation dome to look around. The high quality display will still not be able to replicate your natural stereoscopic vision.

And before anyone says you can wear 3D glasses, just don't.

One or two viewing areas sound acceptable. For rooms, use cameras and displays, The tech is around now to do a good enough job

Way to miss the point on the military cameras though. The point being that there are cameras, and there a very good cameras.

Oh, and some military purchasing is so stupid they do indeed buy stuff they don't need. This is a fact. Unable to give citation for confidentiality reasons.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 02/22/2017 03:59 pm
Return to Thistle Dome

aka "Project Eagle (http://blackbirdinteractive.com/news/project-eagle/)"   :D

Funny that they would choose just the same spot as the very notional Thistle Dome (http://forum.nasaspaceflight.com/index.php?topic=41427.msg1608957#msg1608957).  And judging from the "main well" callout, they found our hypothetical aquifer.  Lucky them.  ;)

(http://cdn.mos.cms.futurecdn.net/TcVCxrqP7kC3abwdCYQtcm.jpg)

(http://cdn.mos.cms.futurecdn.net/PfDBFgenB7yZKpiay2nwcm.jpg)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/22/2017 04:45 pm
Return to Thistle Dome

Funny that they would choose just the same spot as the very notional And judging from the "main well" callout, they found our hypothetical aquifer.  Lucky them.  ;)


Very nice.  Wish I had that kind of computing power and time.
Not certain the dome would hold up to the pressure, but it sure is pretty.
Very close to what we have worked out here, no?
Title: Re: Envisioning Amazing Martian Habitats
Post by: colbourne on 02/25/2017 08:29 am
To minimise the mass required to be transported from Earth to build the habitats, would it be possible to construct a habitat using Mars grown produce. Could a dome be built air tight using leaves or skins frozen together and probably covered with soil ?
The aim is to build a stand alone colony and assuming all contact was lost with Earth what other than tunnels and ice covered domes (igloos) are the potential options. Concrete and glass production will need huge energy and machine costs and might be many years into the isolated colonies future before practical.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 02/25/2017 03:04 pm
Yes you could build with bioplastic, which contains hydrogen, oxygen and carbon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 02/25/2017 05:46 pm
Why does the video show winged vehicles?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jeff Lerner on 03/11/2017 09:44 pm
How about 3D printing Martian habitats .....

http://apis-cor.com/en/
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/12/2017 03:50 am
How about 3D printing Martian habitats .....

Compression structure, we need a tensile structure. Even with bonding-reinforcement between the layers, it can't hold an internal pressure -- unless you bury it under sufficient regolith to counter the outward force.

In which case, if you're going to bury it anyway, why not just use an inflatable form and bury that? (Maybe spray-coat the outside (shotcrete over reinforcing mesh) before you bury it, so you can deflate the mould form and use it again. And maybe add another reinforced layer over the regolith, to stabilise the pile for safety and to let you attach external structures.)



Off-topic aside: 3d printed concrete houses seems like a technology in search of an application. The whole point of 3d printing is that it allows you to create much more complex forms without the steps required in normal manufacturing, or even forms that are impossible with normal manufacturing. Straight walls, square windows and doors, these are not the things that make buildings expensive. I did this stuff with my Dad when I was a teenager, and that demo was not a complex build. The biggest time-killer in concreting is boxing up the steel rebar. (Something I noticed absent from their video. Their hollow-wall zig-zag pattern is essentially re-creating a besser-block wall; something that does not take long to build.)

You want to invent a machine to radically change building with concrete? Create a "3d printer" that extrudes self-supporting basalt-fibre rebar mesh on-site, in the shape of the desired box-work.

(http://www.friends4expo.org/images/pico-3910-1024.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 03/12/2017 04:20 pm
Concrete will be tricky on mars, no limestone.

It could be marscrete. A material made from local resources, not limestone. It needs less energy to produce, too.The material is even better than normal concrete except it is not very resistant to water. Not a concern on Mars.

https://www.youtube.com/watch?v=PmC3NZoiMzQ
This stuff sounds like a real winner for Mars. Multiple potential raw materials (at least some already confirmed on Mars, hopefully the ideal source will be as well). Minimal water usage. Substantially less energy and physical properties as good as (or maybe a bit better) than conventional Portland cement. Sticks to almost anything so good for air sealing caves as well.

It's water stability may be a slight issue. Obvious ideas would be to make it the external structural shell for a pressure tight internal membrane (so all the rest of the regolith can be scooped on top of it. Or the surface can be sealed with some kind of watertight  coating (essentially high tech paint).

Energy wise this sounds like it would be a much better idea to do focused solar rather than the trouble of PV arrays to electricity to heat.

It sounds like you could build hardware on a viable scale for Mars that could really do this, provided you can land somewhere near the necessary supplies of raw materials.

[EDIT I'll note this is V 0.1 technology, hence the large proportion of trapped air. On Mars I would not expect this to be a major issue, with a near vacuum available at the opening of a tap to the outside, if the use of a vibrator is not enough ]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/13/2017 03:22 am
Energy wise this sounds like it would be a much better idea to do focused solar rather than the trouble of PV arrays to electricity to heat.

Atmospheric dust scatters sunlight amazingly well. Even on a bright clear day on Mars, you can lose 30% of direct light. Concentrator-mirrors can't work with scattered light, but solar panels are barely affected. Additionally, solar panels produce general purpose electricity (obviously), which can be diverted to any use, especially in an emergency. Solar furnaces will be single-purpose dedicated systems, nearly worthless for backing up other systems.

So, IMO, even with the loss of efficiency with solar PV, the net benefits vastly outweigh the costs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 03/14/2017 10:21 pm
Energy wise this sounds like it would be a much better idea to do focused solar rather than the trouble of PV arrays to electricity to heat.

Atmospheric dust scatters sunlight amazingly well. Even on a bright clear day on Mars, you can lose 30% of direct light. Concentrator-mirrors can't work with scattered light, but solar panels are barely affected. Additionally, solar panels produce general purpose electricity (obviously), which can be diverted to any use, especially in an emergency. Solar furnaces will be single-purpose dedicated systems, nearly worthless for backing up other systems.

So, IMO, even with the loss of efficiency with solar PV, the net benefits vastly outweigh the costs.
The trouble with any sort of bulk material processing (and if people are serious about mass settlement that's what's needed) is they are going to need a lot of raw heat energy.

Multi junction PV's can give 46% efficiency but IIRC they use (focusing) concentrators anyway. OTOH thin film systems have hit 20%+, although less in complete modules. However either ends up dumping the rest as heat. On Mars this should be quite valuable but it won't be anywhere near the temperatures needed to process minerals.

BTW a focused system may lose 30% due to dust scattering. That leaves 70% as usable energy. The reduced gravity also implies you can build large reflector structures with less material to give the same stiffness as Earth.

My instinct is you will need a PV power array but also some focused heat system for multiple materials processing tasks. This is the simplest way to harvest energy from the environment. It has a good TRL and it's much easier (in principal) to build out than PV arrays (excluding possibly thin film types).
In complexity terms it would be this, then biogas then geothermal, then PV, with nuclear a long way down the road.

It's only when you start digging into this stuff you realize how convenient a really large supply of coal or a hydroelectric dam is.  :(
Title: Re: Envisioning Amazing Martian Habitats
Post by: ThereIWas3 on 03/14/2017 10:24 pm
Do high-temp solar furnace processing on Phobos?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 03/16/2017 07:47 am
Do high-temp solar furnace processing on Phobos?

I see a problem there.  Isn't Phobos tidally locked to Mars ?  At the speed it orbits at you would have a hard time keeping anything focused.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/16/2017 10:54 am
Hmm, photovoltaics deployed on the surface of Mars will most probably be less complex than a system that involves flying back and forth between Phobos and the Martian surface.

Roll-out thin-film PV sheets (tied down to the Martin surface so they won't lift off when a cleaning dustdevil passes) are basically maintenance-free and highly dependable. I am quite sure they will provide the energy needed on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 03/16/2017 01:37 pm
Hmm, photovoltaics deployed on the surface of Mars will most probably be less complex than a system that involves flying back and forth between Phobos and the Martian surface.
True.
Quote from: Oersted
Roll-out thin-film PV sheets (tied down to the Martin surface so they won't lift off when a cleaning dustdevil passes) are basically maintenance-free and highly dependable. I am quite sure they will provide the energy needed on Mars.
I wouldn't bet on that. Roughly speaking Sunlight at Mars surface is about 59% of Earth at SL. Lab scale thin films have hit 20% efficiency and should be available by the time of a landing but that gives you about 120W/m^2 of surface, rather than the close to 200W/m^2 you can expect at the Earths surface.

That might be fine for electricity use but will cause trouble once you get into "bulk" energy use, like driving rock breaking, rock moving and materials processing. Some of those are just better suited to having the heat generated directly and applied to the problem.

For radiation shielding the best habitats are likely to be either underground or in a cliff face.

However that does not necessarily mean they have to cramped and/or badly lit.  :(
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/16/2017 02:44 pm
Thanks for your reply, John. However, I don't understand what the problem is. If you need more electricity for energy-intensive construction work you would just lay out more PV film, wouldn't you? It is not as if they lack real estate on the surface. Or is there a problem with having a lot of PV sheets generating electricity without "tapping it off"? Sorry, I just don't know.

I totally agree that tunneling is the way to go for the initial habitats and internal space. That has been quite conclusively proven in this thread, I think, and Musk seems to have arrived at the same conclusion it seems, given his new-found interest in the subject.
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 03/16/2017 09:06 pm
Thanks for your reply, John. However, I don't understand what the problem is. If you need more electricity for energy-intensive construction work you would just lay out more PV film, wouldn't you? It is not as if they lack real estate on the surface. Or is there a problem with having a lot of PV sheets generating electricity without "tapping it off"? Sorry, I just don't know.
Electricity is useful for some things and the substantial losses (roughly speaking Mars surface at Noon will give you 12% what the same 20% efficient thin film array would give you at the Earth's surface) IOW throw away 88% of the available sunlight from Earth orbit.

In contrast using solar concentrators (imagine or non imaging) may lose 30% due to dust scatter. That leaves 70% as available energy that can be used to process materials.

One conversion process leaves you leaves you with <20% of your input power (at Mars orbit, which is 41% down on Earth). The other leaves you with 70% as concentrated sunlight.  Neither works after sun down and bulk power storage remains difficult.

In general when it comes to bulk mfg people tend to avoid electricity as a heat source unless there are issues with purity (such as chip mfg) or the most efficient method is electro chemical (for Aluminum smelting). They prefer to work with direct combustion of either a fuel or the raw materials themselves. Without coal or coke you're left with biogas, solar PV or solar thermal.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 03/17/2017 09:52 pm
Why not both? Mirrors to concentrate more sunlight into panels?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 03/18/2017 03:28 am
Why not both? Mirrors to concentrate more sunlight into panels?

Scattering from dust/haze in the atmosphere. The panels themselves don't care what direction the light comes in from but reflectors do. If a large percentage of the light delivered to the panels comes off the reflectors there's a huge drop in power output whenever the weather isn't clear.

Works wonderfully when it does work but a lots of panels approach does better in less than ideal conditions. And anything needing lots of power is probably going to work better with a smaller but less variable supply.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/18/2017 08:08 am
In contrast using solar concentrators (imagine or non imaging) may lose 30% due to dust scatter. That leaves 70% as available energy that can be used to process materials.

That 70% is best case, on clear mid-summer days at noon, during low-storm years. It's generally much worse. The MER rovers have seen numbers under 2%. (Oppy under 0.5%.) Concentrator-reflectors are a bad idea on Mars.

For example: At Opportunity's site, transmissivity hasn't gotten above 60% for the last 11 months. And is currently at around 20% direct light.

The efficiency of concentrator reflectors directly correlates with focused sunlight, hence will correlate directly with transmissivity. Can an industrial process even operate if it's receiving 20% of it's rated heat? I mean work at all, there will surely be a minimum before the process doesn't work. Boltzmann's law and all that.

PV panels are happy with indirect sky glow. Oppy's solar panels are currently (with ~20% direct transmission) at 2/3rds of the capacity they were 11 months ago (with~60% direct transmission), with roughly similar levels of dust on the PV-array. PV arrays are more consistent and reliable. And during really bad times, you can turn off the heavy-industry production and divert that extra PV acreage to essential services. It's just electricity through wires. You can't do that with concentrator reflectors, they are site-specific, hence task specific.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 04/11/2017 08:52 am
Nylon would be a really useful material for clothing (even spacesuits) and 3D printers. Maybe with a big enough 3D printer habitats could be printed.

This would seem to also have a possible application for Mars;

Quote
Can Nylon Be Made From Water, Sunshine and Plant Waste? (http://apparel.edgl.com/news/Can-Nylon-Be-Made-From-Water,-Sunshine-and-Plant-Waste-109396)
— April 09, 2017

Currently, many types of fabrics, including nylon, are made in an energy-intensive, unsustainable process that uses fossil fuel. Now, NYU Tandon School of Engineering Assistant Professor Miguel Modestino, of the Department of Chemical and Biomolecular Engineering, is proposing a method that eliminates oil from the equation, employing water, plant waste and solar energy to deliver a material identical to the nylon now widely used in the fashion industry and in other commercial applications.

Modestino and his co-researcher, Sophia Haussener of the École Polytechnique Fédéral de Lausanne (EPFL), have garnered a 2017 Global Change Award of €250,000 ($267,000) from the H&M Foundation, the non-profit arm of the retailing giant. The first such initiative by a major member of the fashion world, the Global Change challenge attracted almost 3,000 applicants this year and aims to support early innovations that can accelerate the shift to a circular and sustainable garment industry, in order to protect the planet. The awards were presented in Stockholm, Sweden, on April 5.

The researchers chose to focus on nylon because of the large market for the popular polymer, which they estimate to be more than 6 million tons per year, with a value of more than $20 billion. Their proposed process uses photovoltaic arrays, which generate electricity directly from the sun, to drive the electrochemical reduction of acrylonitrile (ACN) to adiponitrile (ADN) and hydrogen (H2), which will, in turn, be synthesized into hexanediamine (HDA), one of the existing precursors to nylon.

Because ACN can be derived from plant waste, only sun, water and carbon dioxide will be required as inputs, and the new process will represent a new scheme for carbon capture, where greenhouse gases will be bound into the fabric, rather than releasing them into the air.

(http://i.imgur.com/UKoiz1k.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 04/17/2017 02:10 pm
Robust and Elastic Lunar and Martian Structures from 3D-Printed Regolith Inks (https://www.nature.com/articles/srep44931)

(http://i.imgur.com/Fo0ffMQ.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 04/27/2017 07:52 pm
Martian bricks will seemingly be very easy to  make by just compressing the soil:

http://www.realclearscience.com/quick_and_clear_science/2017/04/27/martian_soil_could_be_used_to_build_a_colony.html

"Creating the bricks was surprisingly simple. Yu Qiao, a Professor of Structural Engineering, and his team dried out simulated Martian soil, compressed it at high pressures in steel molds, and then subsequently allowed it to dry again. The resulting blocks were incredibly strong and had a permeability similar to dense rocks. This latter feature is important, because it means a structure built with the bricks could be adapted to hold an atmosphere [...]"

"The secret ingredient allowing for the formation of these bricks seems to be the iron oxide that gives the Martian soil its patented red hue. Under crushing pressure, the iron oxide morphs into a denser form, binding the surrounding regolith together in the process."

Article in Nature:
https://www.nature.com/articles/s41598-017-01157-w
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 04/28/2017 06:06 pm
From MIT: Digital Construction Platform,

Quote
It can be fitted with a range of different tools, including a foam insulation gun, a welding attachment, a “thermoplastic extruder” that squirts out melted plastic, a glorified squirt gun, and even a simple bucket.

The Verge.... (http://www.theverge.com/platform/amp/2017/4/27/15447578/autonomous-robot-3d-printers-mit-homes-planets)

https://www.youtube.com/watch?v=8zt_3Gs1ksg
Title: Re: Envisioning Amazing Martian Habitats
Post by: Hotblack Desiato on 07/31/2017 03:57 pm
Regarding 3D-printing large objects:

https://youtu.be/_GlxVjAHofk

The US Navy has released this nice video regarding printing entire submarine hulls.

They need to be tight (if they want it to be crewed), and need to be able to withstand a substantial pressure difference inside - outside (just the other way around of what's needed for a station on Moon, Mars, or in space itself).

So, it is possible to directly print the main structural parts of a surface module.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Chris_Pi on 08/07/2017 09:25 pm
It's probably a free-flooding design - Flat sides like that aren't much good for pressure vessels. Diving gear for everyone anyways to get in/out. Mostly a frame for a motor/batteries, seats, gear storage and a bit of electronics with an outer shell around those. Think underwater golf cart more than submarine.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 08/28/2017 08:13 pm
Some company called Tenfold Engineering makes these building structures which unfold:

https://www.youtube.com/watch?v=MmYRj0pqb_s

Could this be a way to build living quarters on Mars? I wonder if their technology resulted as a spin-off from space hab research?

I would've preferred Thunderbirds theme music, btw.
Title: Re: Envisioning Amazing Martian Habitats
Post by: whitelancer64 on 08/28/2017 08:50 pm
Some company called Tenfold Engineering makes these building structures which unfold:

**Youtube Vid**

Could this be a way to build living quarters on Mars? I wonder if their technology resulted as a spin-off from space hab research?

I would've preferred Thunderbirds theme music, btw.

It's nice, but remember, all that would need to be unfolding inside a pressure vessel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sanman on 08/28/2017 08:59 pm

It's nice, but remember, all that would need to be unfolding inside a pressure vessel.

Maybe inside a cave or lava tube that had been sealed and pressurized?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/28/2017 09:14 pm
Some company called Tenfold Engineering makes these building structures which unfold:

https://www.youtube.com/watch?v=MmYRj0pqb_s

Could this be a way to build living quarters on Mars? I wonder if their technology resulted as a spin-off from space hab research?

I would've preferred Thunderbirds theme music, btw.
More likely research into campers for happy retirees and expandable containers for disaster relief.
The problem for long term habitation is not packaging, it's the required mass for long term radiation protection.  And you can't fold that away. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 09/02/2017 01:17 pm
From MIT: Digital Construction Platform,

Quote
It can be fitted with a range of different tools, including a foam insulation gun, a welding attachment, a “thermoplastic extruder” that squirts out melted plastic, a glorified squirt gun, and even a simple bucket.

The Verge.... (http://www.theverge.com/platform/amp/2017/4/27/15447578/autonomous-robot-3d-printers-mit-homes-planets)

https://www.youtube.com/watch?v=8zt_3Gs1ksg
Wow. I have seen the future of cake decorating, and it works.  :)

Radiation shielding keeps being the issue. Somehow you have put about 3m of regolith, or its equivalent, between the settlers and the sky.  :(
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 09/02/2017 04:49 pm
Radiation shielding keeps being the issue.

As has been pointed out before in this and similar threads, radiation is much, much less of an issue for Mars.

(While I don't accept that it's "not an issue", it is reduced enough, compared to other problems, to be considered an afterthought, not a core consideration in the design.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 09/03/2017 02:39 am
I agree, assuming you've solved all your other harder problems (like regolith movers that are light enough to ship to Mars yet heavy enough to function, and powering them, and so on), dumping a bunch of regolith on top of your structures should be relatively easy.

Building the actual habitats, or deploying them, or tunneling them, or whatever - these are much harder than simply shielding them with regolith. By the time you get to shielding them, that problem is pretty much solved by all your other efforts.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 09/03/2017 03:01 am
By the time you get to shielding them, that problem is pretty much solved by all your other efforts.
Water is a good option. It needs to be priority #1 for return fuel anyway. It might not even involve any significant digging. 3 alternatives are pumping hot gas or liquid through a small bore, extraction from atmosphere, or landing on exposed ice.

You could let it freeze to ice, but I like the idea of a roof pool for swimming in.

This pool might also be useful for storing heat and equalising temperature between night and day.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/03/2017 10:58 pm
Radiation shielding keeps being the issue. Somehow you have put about 3m of regolith, or its equivalent, between the settlers and the sky.  :(

Why the sad smiley? - The technology to do that has existed for at least 2000 years....  https://en.wikipedia.org/wiki/Qanat
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 09/04/2017 12:36 pm
I like the idea of mining water with the bore hole and hot water(or other fluid) to melt the buried ice and bring it to the surface. It seems to be the preferred method to mine sulfur and lithium on earth.

Once you have water on the surface it can be used like quick setting cement. And many other uses.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 09/04/2017 02:25 pm
HP's vision of an Amazing Martian Habitat

https://youtu.be/GrJufEORMoQ
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 09/04/2017 06:59 pm
I created an account to see inside. Interesting. It is like HP is trying to crowdsource ideas over a wide range of applicable areas. Be careful of what ideas you share in this space. Read the terms carefully before sharing any ideas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DOCinCT on 09/04/2017 08:07 pm
Radiation shielding keeps being the issue. Somehow you have put about 3m of regolith, or its equivalent, between the settlers and the sky.  :(

Why the sad smiley? - The technology to do that has existed for at least 2000 years....  https://en.wikipedia.org/wiki/Qanat
Use of caves for shelter likely goes back 1 million years.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 09/05/2017 12:24 am
I created an account to see inside. Interesting. It is like HP is trying to crowdsource ideas over a wide range of applicable areas. Be careful of what ideas you share in this space. Read the terms carefully before sharing any ideas.
Unless you are me, and think the chances of monetising any of the crap you come up with is nil.

Personally I just throw it around like an angry monkey  :)

I like the idea of mining water with the bore hole and hot water(or other fluid) to melt the buried ice and bring it to the surface. It seems to be the preferred method to mine sulfur and lithium on earth.

Once you have water on the surface it can be used like quick setting cement. And many other uses.


Interesting! I hadn't heard of that. Searched and found this:
https://en.wikipedia.org/wiki/Frasch_process
Title: Re: Envisioning Amazing Martian Habitats
Post by: JamesH65 on 09/05/2017 11:50 am
Radiation shielding keeps being the issue. Somehow you have put about 3m of regolith, or its equivalent, between the settlers and the sky.  :(

Why the sad smiley? - The technology to do that has existed for at least 2000 years....  https://en.wikipedia.org/wiki/Qanat
Use of caves for shelter likely goes back 1 million years.

545M years or thereabouts; caves and crevices have been used for shelter since the evolution of the eye at or around the Cambrian explosion.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/09/2017 08:51 pm
Radiation shielding keeps being the issue. Somehow you have put about 3m of regolith, or its equivalent, between the settlers and the sky.  :(

Why the sad smiley? - The technology to do that has existed for at least 2000 years....  https://en.wikipedia.org/wiki/Qanat
Use of caves for shelter likely goes back 1 million years.


I was referring to building your own tunnels, not using caves formed by nature. There is quite a long discussion in this thread about excavating tunnels on Mars vs. using lava tubes. I don't believe so much in the latter...
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 09/10/2017 06:02 am
I was referring to building your own tunnels, not using caves formed by nature. There is quite a long discussion in this thread about excavating tunnels on Mars vs. using lava tubes. I don't believe so much in the latter...

I mostly agree. There may come a day when mega cities are built in many locations on Mars. Lava tubes may be the best option then. But that is a long time off.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 09/10/2017 08:38 am
1) find cliff face, mountainside, big plateau rock etc.

2) dig basic tunnels using Boring Co. TBM's.

3) do the internal contouring of chambers using Mars-adapted roadheaders. See the opal miner "cave  homes" in  Coober Pedy, Australia.

4) seal walls, add airlocks, ECLSS etc.

5) move in.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 09/10/2017 02:55 pm
1) find cliff face, mountainside, big plateau rock etc.

2) dig basic tunnels using Boring Co. TBM's.

3) do the internal contouring of chambers using Mars-adapted roadheaders. See the opal miner "cave  homes" in  Coober Pedy, Australia.

4) seal walls, add airlocks, ECLSS etc.

5) move in.

I don't know if the perfect location exists, but some glaciers may provide hundreds of meters of ice up against a rock face like you're suggesting. In that case ice mining excavates a large volume between the rock face which could be terraced and bored for the city and the ice face which would along with a roof contain atmosphere. Aerogel insulation of the ice face (aerogels made with local silica and CO2) allows a warm environment with a lake at the bottom level and other water features. Aerogels make for interesting lighting effects with light piped in from above or leds. The ice face might look a lot like a distant sky above a sea from the terraced cliff city, a bit like the Ligurian coast of Italy but larger and with more architectural variety.

I think much of the weight of the roof spanning the rock face and the ice face in one third gravity would be supported by the air pressure it contains.

This makes for a terraced cliff side city with a view of a spacious outdoor like volume created as a side effect of ice mining that would happen anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/12/2017 07:46 pm
From Gwynne Shotwell Q&A:

(This is not verbatim, but from notes by Reddit-user "Sticklefront": https://www.reddit.com/r/spacex/comments/75ufq9/interesting_items_from_gwynne_shotwells_talk_at/)

"Will SpaceX work with other companies regarding infrastructure on the surface of Mars?

SpaceX is focused on the transportation part of the Mars problem, but people need somewhere to go once they arrive. I don't think it's an accident that Elon started the Boring Company, tunnels will be very important in the first steps of living on Mars, before we build domes and terraform. We want other companies to start thinking about it and working on it, but we'll do it if we have to. I think the BFR might be ready before these other components of actually living on Mars."
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 10/12/2017 08:20 pm
1) find cliff face, mountainside, big plateau rock etc.

2) dig basic tunnels using Boring Co. TBM's.

3) do the internal contouring of chambers using Mars-adapted roadheaders. See the opal miner "cave  homes" in  Coober Pedy, Australia.

4) seal walls, add airlocks, ECLSS etc.

5) move in.

I don't know if the perfect location exists, but some glaciers may provide hundreds of meters of ice up against a rock face like you're suggesting. In that case ice mining excavates a large volume between the rock face which could be terraced and bored for the city and the ice face which would along with a roof contain atmosphere. Aerogel insulation of the ice face (aerogels made with local silica and CO2) allows a warm environment with a lake at the bottom level and other water features. Aerogels make for interesting lighting effects with light piped in from above or leds. The ice face might look a lot like a distant sky above a sea from the terraced cliff city, a bit like the Ligurian coast of Italy but larger and with more architectural variety.

I think much of the weight of the roof spanning the rock face and the ice face in one third gravity would be supported by the air pressure it contains.

This makes for a terraced cliff side city with a view of a spacious outdoor like volume created as a side effect of ice mining that would happen anyway.

There exists, somewhere here on NSF a detailed discussion of greenhouses and domes on Mars thread. The take away from my perspective is the lack of consideration of the massive air pressure that Mars sited structures must contain. Air pressure on Mars is effectively zero relative to standard sea level pressure here on Earth. That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft or 20+ tons per square meter. Twenty tons is the mass of a one meter square column of water 20 meters tall on Earth, on Mars where gravity is only about 38 percent of earth, the column would need to be over 52 meters tall.

The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/12/2017 08:27 pm
There exists, somewhere here on NSF a detailed discussion of greenhouses and domes on Mars thread. The take away from my perspective is the lack of consideration of the massive air pressure that Mars sited structures must contain. Air pressure on Mars is effectively zero relative to standard sea level pressure here on Earth. That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft or 20+ tons per square meter. Twenty tons is the mass of a one meter square column of water 20 meters tall on Earth, on Mars where gravity is only about 38 percent of earth, the column would need to be over 52 meters tall.

The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.

1 atm is 10 tonnes per square meter. Skin tension in the vessel membrane, or internal tension elements, can take the pressure. The former works fine up to about 10-15 meters diameter, and the latter can make much larger structures.

Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 10/12/2017 08:27 pm


The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.

I don't get it. The ISS is made from a few centimeters of aluminum and is in vacuum. It does not blow up. Why would things be different on the surface of Mars?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/12/2017 08:39 pm

There exists, somewhere here on NSF a detailed discussion of greenhouses and domes on Mars thread. The take away from my perspective is the lack of consideration of the massive air pressure that Mars sited structures must contain. Air pressure on Mars is effectively zero relative to standard sea level pressure here on Earth. That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft or 20+ tons per square meter. Twenty tons is the mass of a one meter square column of water 20 meters tall on Earth, on Mars where gravity is only about 38 percent of earth, the column would need to be over 52 meters tall.

The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.

Common sense tells me that just can't be right. Waiting for someone to step in with a better argument than mine!

Anyway, I am thrilled that Shotwell confirms tunnels will be a major part of the first Mars habitats! - We had already arrived at that conclusion in this thread...
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 10/12/2017 08:42 pm


The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.

I don't get it. The ISS is made from a few centimeters of aluminum and is in vacuum. It does not blow up. Why would things be different on the surface of Mars?


The internal air pressure on the ISS keeps the aluminium in tension and aluminium in very strong in tension. Many materials used in civil engineering construction (concrete, bricks etc) are strong in compression but weak in tension. As the internal air pressure would put them in tension, you need countervailing forces from surrounding rock or overlying regolith to keep the materials in compression.

Of course, you can build your habitats from materials that are strong in tension. But concrete and brick have their own advantages.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/12/2017 09:42 pm
The ice face might look a lot like a distant sky above a sea from the terraced cliff city, a bit like the Ligurian coast of Italy but larger and with more architectural variety.

Minor question, but why would the architecture be more varied?

I think much of the weight of the roof spanning the rock face and the ice face in one third gravity would be supported by the air pressure it contains.

Under Mars gravity and at roughly 1atm, you can support, from air-pressure alone, around 26 tonnes of material per square metre. So about 26 metres of water ice, maybe 10-12m of light rock, or maybe 3 metres of solid iron.

However, that assumes the materials have no other support, individual weights rather than a continuous structure. Obviously any structural gain from their layout will reduce their containment ability, so increase the risk of a blow-out. Flip side, faults within the inside face of the material may cause it to fall away, since once air can get into cracks, the material below the crack is not supported by air pressure. IMO, you wouldn't want to rely on air pressure alone for structural support. Even in an entirely engineered structure like a pressure vessel, you want to make sure it can support its own weight when unpressurised.



That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft.
Skin tension in the vessel membrane, or internal tension elements, can take the pressure.

He was replying to a comment talking about using ice/rock as "skin".



That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft or 20+ tons per square meter.

Converting from square feet to square metres looks like where you made your mistake. There's 10.7 sq_ft in 1 sq_m.

(This is how you lose space probes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/12/2017 09:42 pm
There is quite a long discussion in this thread about excavating tunnels on Mars vs. using lava tubes. I don't believe so much in the latter...

What don't you believe? That they exist, or that they are useful?



Aside: I've mentioned before that the temperature underground tends towards the average of the temperature on the surface. The deeper you go, the longer the averaging period. Below a few metres and the temperature is the yearly surface average.

Lava tubes on Mars should be permanently below freezing (but never as low as the winter or night-time temperatures). Breaks in the walls allows air to mix, so you should get preferential freezing of volatiles (at least water) inside the tube as you do at the poles. Most lava tubes might be filled with tens to hundreds of millions of years of accumulated water ice.

A shelter, a shield, and a resource, all in one neat package.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 10/13/2017 02:00 am
@ envy887,  @Paul451

I re-checked and you're right. One atmosphere pressure per square meter is about 10 metric tonnes or 10 long tons.

That might be why I thought that folks on the other thread underappreciated the force from air pressure inside the habitat.

Of course, there are solutions if the infrastructure exists to implement them. Bigalow habitats come to mind, and we obviously can construct rather large spaceships that will withstand the pressure. Just don't count on the regolith to hold the air in. Use it for radiation shielding over a pressure vessel, that's good, but windows? Large windows are questionable in my mind although the BFS is planned to have a rather large one. I am of the further opinion that a direct view of the outside would be good for the mental health of the colonists although cameras outside and video screens might be enough. Transparent sci-fi domes over a large, shirt sleeve environment? Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/13/2017 03:56 pm
Transparent sci-fi domes over a large, shirt sleeve environment? Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.

There are ways to do this, e.g multi-pane Lexan windows in a carbon fiber geodesic frame dome. But it's expensive, and probably still needs cables and ground anchors both throughout the area of the dome, and around the perimeter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/13/2017 04:20 pm

Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.
ALON Aluminum oxynitride
https://en.wikipedia.org/wiki/Aluminium_oxynitride
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/13/2017 04:51 pm
That might be why I thought that folks on the other thread underappreciated the force from air pressure inside the habitat.

No-one does. I know the numbers and yet it still weirds me out. (In two completely contradictory ways: We have ten tonnes of air per metre constantly pressing down on us and don't notice. OTOH, the weight of the entire atmosphere is only equivalent to a ten metre depth of water. If you liquefied the entire atmosphere, it would only be about 10-11m deep.)

Transparent sci-fi domes over a large, shirt sleeve environment? Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.

The "roof" of the dome itself could be made strong enough to stand up to the forces, even over large diameters. The two big issues for domes are that the air pressure will be trying both rip the dome off its foundations and trying to bow the bottom of the "walls" out. The maximum force will be right where the dome attaches to the base. (The other issue is that a regolith floor won't seal against the air leaking out, so you need to seal the floor... In which case, why bother with a dome, why not just build a decent pressure-vessel.)

Use it for radiation shielding over a pressure vessel

Radiation dosage on the surface is less than in open space. Half because of the planet (duh), then half again because of the atmosphere. You don't need as much protection as on a ship, plus if you are careful with your dosages, it should be possible to for.eg sleep in a protected area, but spend a reasonable chunk of time in unprotected windowed areas. And in non-government, self-funded settlements, people might see the radiation risk as less important than other colonisation risks. People still smoke, after all. People work in dangerous professions. And travelling in space and living on Mars is going to be inherently more dangerous than living in a western city on Earth. It's going to be awhile before Mars wins any "Safest City On Earthhumanoccupiedspace" awards.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/13/2017 06:11 pm
Seems like somebody has already designed and built pressure vessels. Bigelow anyone?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 10/13/2017 07:04 pm
That might be why I thought that folks on the other thread underappreciated the force from air pressure inside the habitat.

No-one does. I know the numbers and yet it still weirds me out. (In two completely contradictory ways: We have ten tonnes of air per metre constantly pressing down on us and don't notice. OTOH, the weight of the entire atmosphere is only equivalent to a ten metre depth of water. If you liquefied the entire atmosphere, it would only be about 10-11m deep.)

Transparent sci-fi domes over a large, shirt sleeve environment? Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.

The "roof" of the dome itself could be made strong enough to stand up to the forces, even over large diameters. The two big issues for domes are that the air pressure will be trying both rip the dome off its foundations and trying to bow the bottom of the "walls" out. The maximum force will be right where the dome attaches to the base. (The other issue is that a regolith floor won't seal against the air leaking out, so you need to seal the floor... In which case, why bother with a dome, why not just build a decent pressure-vessel.)

Use it for radiation shielding over a pressure vessel

Radiation dosage on the surface is less than in open space. Half because of the planet (duh), then half again because of the atmosphere. You don't need as much protection as on a ship, plus if you are careful with your dosages, it should be possible to for.eg sleep in a protected area, but spend a reasonable chunk of time in unprotected windowed areas. And in non-government, self-funded settlements, people might see the radiation risk as less important than other colonisation risks. People still smoke, after all. People work in dangerous professions. And travelling in space and living on Mars is going to be inherently more dangerous than living in a western city on Earth. It's going to be awhile before Mars wins any "Safest City On Earthhumanoccupiedspace" awards.

Right, and if your city is in a canyon, then the radiation is reduced even further. The average American is said to spend 87% of their life indoors, with a further 6% of their life in automobiles. So if you have a dome in a canyon on Mars, with shielded buildings and transport, then the dosage doesn't seem to be too bad.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DreamyPickle on 10/13/2017 08:44 pm
Bigelow modules seems like they would be the most mass-efficient way to provide habitable volume. But they're still designed primarily for operation in orbit. Would it be possible to build lighter and more compact habitats focused towards planetary surfaces? In particular you could rely on regolith for shielding from radiation and micrometeoroids.

Just imagine two berthing ports joined by a big elongated balloon. This is shipped as a compact cylindrical crate similar to BEAM. Deployment requires astronauts to place the ports at ground level and then pressurize it, after it's inflated regolith is poured on top until it covers the top with at least 30cm or so. All equipment inside (including life support) is shipped separately, moved in through airlocks and installed by astronauts.

For large diameter modules a hole would have to be dug first so the habitat can expand without lifting the ports. Modules would join to each other or to solid 4-way hubs.

This plan requires heavy earth-moving equipment but the mission already assumes mining hundreds of tons of ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 10/13/2017 09:23 pm
Bigelow modules seems like they would be the most mass-efficient way to provide habitable volume. But they're still designed primarily for operation in orbit. Would it be possible to build lighter and more compact habitats focused towards planetary surfaces? In particular you could rely on regolith for shielding from radiation and micrometeoroids.

Just imagine two berthing ports joined by a big elongated balloon. This is shipped as a compact cylindrical crate similar to BEAM. Deployment requires astronauts to place the ports at ground level and then pressurize it, after it's inflated regolith is poured on top until it covers the top with at least 30cm or so. All equipment inside (including life support) is shipped separately, moved in through airlocks and installed by astronauts.

For large diameter modules a hole would have to be dug first so the habitat can expand without lifting the ports. Modules would join to each other or to solid 4-way hubs.

This plan requires heavy earth-moving equipment but the mission already assumes mining hundreds of tons of ice.
You mean something like this
https://youtu.be/pk9PWUGkz7o
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/13/2017 09:28 pm
So if you have a dome

Well, not that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Kansan52 on 10/13/2017 09:43 pm
Bigelow has pitched surface based units.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/13/2017 10:13 pm
Bigelow has pitched surface based units.

For the moon. Mars would require very different modules. The atmosphere provides ample micrometeorite protection. We had this discussion before.

You can not just pour regolith on top of a habitat, especially not an inflatable one. You would need to build a self containing structure with the pressurized habitat inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/13/2017 10:20 pm
Transparent sci-fi domes over a large, shirt sleeve environment? Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.
Yeah, transparent tessellated domes like in SpaceX's presentation are totally unrealistic and can never be done unless someone invents unobtainium.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Kansan52 on 10/13/2017 10:21 pm
For me, yes and no. An inflatable could be built to handle the stress and puncture protection. But weight and cost might ruin that idea.

But memory says Bigelow doesn't call there unit inflatable but expandable. I haven't seen anything that states they could be covered in regolith.

Has Bigelow stated the units can't be covered?
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/13/2017 10:25 pm
About the dome anchoring vs "just build a pressure vessel" argument.

Elon Musk isn't discussing details of mining, letting us believe he will go for a fairly brute force approach instead of something like the Frasch process (https://en.wikipedia.org/wiki/Frasch_process)

If they are building a straightforward quarry (https://en.wikipedia.org/wiki/Quarry), then they will have no problem creating a bowl shaped depression to specification and they will have it early. I guess you would need to move multiple times the volume of a BFS, in the form of icy regolith, for every BFS flight. You will be moving even more once you start industry on Mars to build more city components.

I think there will be absolutely no problem building a dome that is also a perfectly good pressure vessel without anchoring. It doesn't have to be a perfect sphere. You can trade off the amount of soil you move with somewhat heavier/volume designs. There may be tricks that exploit the regolith for some support, saving mass for the underside eg cables for most of the strength and just sheeting for sealant, maybe.

My point is just that assuming quarries, domes that are really pressure vessels that do not rely on any anchoring is no problem and IMO you just split the buried underside into levels and use it for workspace and sleeping.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/13/2017 10:27 pm
Transparent sci-fi domes over a large, shirt sleeve environment? Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.
Yeah, transparent tessellated domes like in SpaceX's presentation are totally unrealistic and can never be done unless someone invents unobtainium. [picture of ISS's cupola]

You missed the "large". Meaning the SF image of domed over craters, whole cities, entire canyons.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/13/2017 10:37 pm
About the dome anchoring vs "just build a pressure vessel" argument.

Elon Musk isn't discussing details of mining, letting us believe he will go for a fairly brute force approach instead of something like the Frasch process (https://en.wikipedia.org/wiki/Frasch_process)

If they are building a straightforward quarry (https://en.wikipedia.org/wiki/Quarry), then they will have no problem creating a bowl shaped depression to specification and they will have it early. I guess you would need to move multiple times the volume of a BFS, in the form of icy regolith, for every BFS flight. You will be moving even more once you start industry on Mars to build more city components.

I think there will be absolutely no problem building a dome that is also a perfectly good pressure vessel without anchoring. It doesn't have to be a perfect sphere. You can trade off the amount of soil you move with somewhat heavier/volume designs. There may be tricks that exploit the regolith for some support, saving mass for the underside eg cables for most of the strength and just sheeting for sealant, maybe.

My point is just that assuming quarries, domes that are really pressure vessels that do not rely on any anchoring is no problem and IMO you just split the buried underside into levels and use it for workspace and sleeping.

So, dig a huge hole and build a half-buried spherical pressure vessel in it?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/13/2017 10:41 pm
Transparent sci-fi domes over a large, shirt sleeve environment? Don't count on it until someone invents transparent aluminum or something similar. Even with aluminum, there is a limit to the size before rupture.
Yeah, transparent tessellated domes like in SpaceX's presentation are totally unrealistic and can never be done unless someone invents unobtainium. [picture of ISS's cupola]

You missed the "large". Meaning the SF image of domed over craters, whole cities, entire canyons.
So now you define "large" in absurd terms. Fine, but that's nothing to do with unobtainium ("transparent aluminum") or lack thereof: Only because getting an entire city on Mars (with requisite industrial capacity) is really hard to begin with. From a materials science perspective, we've got everything needed.

What SpaceX showed in their presentation of an early Mars base (we're in the SpaceX section) could be done easily with existing materials. It just costs a lot to ship stuff to Mars and operate there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/13/2017 11:22 pm
I think there will be absolutely no problem building a dome that is also a perfectly good pressure vessel without anchoring.

Thusly?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/13/2017 11:27 pm
So now you define "large" in absurd terms.

Chill, dude. Don't shoot the messenger, I was just giving you my interpretation of Aero's comment. He wasn't talking about something the size of the ISS cupola, he was talking about the classic SF transparent dome-on-Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/14/2017 12:05 am
So, dig a huge hole and build a half-buried spherical pressure vessel in it?
Pretty much. Im not religious about "sphere". If it turns out you want to dig less, you could go with two sphere sections stuck together, with the lower one flatter than the upper one. If it turns out you are going to dig even more anyway, maybe you want to go with a biconic shape.

The only new thing I was really adding was: "look at these bowl-shaped holes we could be digging anyway":
https://en.wikipedia.org/wiki/Quarry
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/14/2017 12:46 am
So, dig a huge hole and build a half-buried spherical pressure vessel in it?
Pretty much. Im not religious about "sphere". If it turns out you want to dig less, you could go with two sphere sections stuck together, with the lower one flatter than the upper one. If it turns out you are going to dig even more anyway, maybe you want to go with a biconic shape.

The only new thing I was really adding was: "look at these bowl-shaped holes we could be digging anyway":
https://en.wikipedia.org/wiki/Quarry

Non-spherical (or non-cylindrical) sections will require internal tension elements. If you're adding internal tension elements, then there's little point in digging a big hole - unless you want to dig anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/14/2017 12:49 am
Not true. Some non-spherical shapes use only tension on the outside. Think like the disk-shaped Mylar balloon. That is actually an interesting case since you can put a zipper along where the folds tend to be without significant stress on the zipper.

https://en.wikipedia.org/wiki/Mylar_balloon_(geometry)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2017 12:50 am
And what will get to mars first. Earth movers(bulldozers) or tunnel borers?
Just put the bigelow modules in the tunnel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/14/2017 12:54 am
And what will get to mars first. Earth movers(bulldozers) or tunnel borers?
Just put the bigelow modules in the tunnel.
Best to just forget about Bigelow for SpaceX's Mars plans, IMHO. The BFS itself is cheaper for habitable volume than a Bigelow module is, even including all the useless overhead of all the fuel tanks and engines and stuff.

For the record, I'd bet on earth (regolith) movers, first.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/14/2017 01:01 am
And what will get to mars first. Earth movers(bulldozers) or tunnel borers?
Just put the bigelow modules in the tunnel.
Best to just forget about Bigelow for SpaceX's Mars plans, IMHO. The BFS itself is cheaper for habitable volume than a Bigelow module is, even including all the useless overhead of all the fuel tanks and engines and stuff.

For the record, I'd bet on earth (regolith) movers, first.

I pretty much agree.
For the start BFS's will be just as good as surface modules. Can't the crew sleep in the radiation safe room in the ship?
Eventually something underground though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/14/2017 01:06 am
Not true. Some non-spherical shapes use only tension on the outside. Think like the disk-shaped Mylar balloon. That is actually an interesting case since you can put a zipper along where the folds tend to be without significant stress on the zipper.

https://en.wikipedia.org/wiki/Mylar_balloon_(geometry)

You can make an inflatable whatever shape you want, but you'll pay a large mass penalty for anything other than a sphere.

Unless it uses gravity to oppose pressure...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/14/2017 01:12 am
Not true. Some non-spherical shapes use only tension on the outside. Think like the disk-shaped Mylar balloon. That is actually an interesting case since you can put a zipper along where the folds tend to be without significant stress on the zipper.

https://en.wikipedia.org/wiki/Mylar_balloon_(geometry)

You can make an inflatable whatever shape you want, but you'll pay a large mass penalty for anything other than a sphere.

Unless it uses gravity to oppose pressure...
Not a large penalty for this shape. The assumption that a sphere is ideal depends on the assumption that the material is isotropic, whereas you're basically guaranteed to use cables as the primary tension carriers.

And since the upper volume of a full sphere is likely to be mostly wasted space anyway, you wouldn't have any mass penalty for using this shape.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/14/2017 02:18 am
And what will get to mars first. Earth movers(bulldozers) or tunnel borers?
Just put the bigelow modules in the tunnel.
Roadheaders!!
And yellow trucks, of course.
You don't need a whole module, just a few strong air tight membranes backed up with rock
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/14/2017 02:24 am
Not true. Some non-spherical shapes use only tension on the outside. Think like the disk-shaped Mylar balloon. That is actually an interesting case since you can put a zipper along where the folds tend to be without significant stress on the zipper.

https://en.wikipedia.org/wiki/Mylar_balloon_(geometry)

You can make an inflatable whatever shape you want, but you'll pay a large mass penalty for anything other than a sphere.

Unless it uses gravity to oppose pressure...
Not a large penalty for this shape. The assumption that a sphere is ideal depends on the assumption that the material is isotropic, whereas you're basically guaranteed to use cables as the primary tension carriers.

And since the upper volume of a full sphere is likely to be mostly wasted space anyway, you wouldn't have any mass penalty for using this shape.

Yep... which is why I said use cables  ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/14/2017 02:38 am
Not true. Some non-spherical shapes use only tension on the outside. Think like the disk-shaped Mylar balloon. That is actually an interesting case since you can put a zipper along where the folds tend to be without significant stress on the zipper.

https://en.wikipedia.org/wiki/Mylar_balloon_(geometry)

You can make an inflatable whatever shape you want, but you'll pay a large mass penalty for anything other than a sphere.

Unless it uses gravity to oppose pressure...
Not a large penalty for this shape. The assumption that a sphere is ideal depends on the assumption that the material is isotropic, whereas you're basically guaranteed to use cables as the primary tension carriers.

And since the upper volume of a full sphere is likely to be mostly wasted space anyway, you wouldn't have any mass penalty for using this shape.

Yep... which is why I said use cables  ;)
But not necessarily required /internally/, as you claimed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DreamyPickle on 10/14/2017 12:07 pm
You can not just pour regolith on top of a habitat, especially not an inflatable one. You would need to build a self containing structure with the pressurized habitat inside.
You mean because of all the weight on top? I might be really dumb but I'm not sure I follow the physics here.

The weight on top should be distributed in a relatively even way and 20-30cm of regolith will push on the membrane less than the 1atm of pressure from below. So it should be largely fine, in fact you could add a lot more that 30cm.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/14/2017 12:11 pm
You can not just pour regolith on top of a habitat, especially not an inflatable one. You would need to build a self containing structure with the pressurized habitat inside.
You mean because of all the weight on top? I might be really dumb but I'm not sure I follow the physics here.

The weight on top should be distributed in a relatively even way and 20-30cm of regolith will push on the membrane less than the 1atm of pressure from below. So it should be largely fine, in fact you could add a lot more that 30cm.
You need 3 to 5 m for high energy galactic cosmic rays in a colony for a lifetime radiation dose protection
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/14/2017 12:16 pm
You can not just pour regolith on top of a habitat, especially not an inflatable one. You would need to build a self containing structure with the pressurized habitat inside.
You mean because of all the weight on top? I might be really dumb but I'm not sure I follow the physics here.

The weight on top should be distributed in a relatively even way and 20-30cm of regolith will push on the membrane less than the 1atm of pressure from below. So it should be largely fine, in fact you could add a lot more that 30cm.

I am of the firm opinion that any habitat needs to be stable both pressurized and unpressurized. Otherwise just partly losing pressure would mean the whole structure comes tumbling down.
Title: Re: Envisioning Amazing Martian Habitats
Post by: colbourne on 10/14/2017 01:04 pm
We dont actually need heavy bulldozers and boring equipment. I am sure some good old fashioned explosive can dig nice holes perfect for housing our flattened sphere or dome.
The dome does not need to be wasted space if you make use of it with multi floors.
 
(sorry for double post. I got mixed up between threads)
Title: Re: Envisioning Amazing Martian Habitats
Post by: colbourne on 10/14/2017 01:07 pm
You can not just pour regolith on top of a habitat, especially not an inflatable one. You would need to build a self containing structure with the pressurized habitat inside.
You mean because of all the weight on top? I might be really dumb but I'm not sure I follow the physics here.

The weight on top should be distributed in a relatively even way and 20-30cm of regolith will push on the membrane less than the 1atm of pressure from below. So it should be largely fine, in fact you could add a lot more that 30cm.

I am of the firm opinion that any habitat needs to be stable both pressurized and unpressurized. Otherwise just partly losing pressure would mean the whole structure comes tumbling down.
It should be possible to mix some kind of binder with the  regolith (might be as simple as water, cement or resin) so that it will harden over time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/14/2017 01:11 pm
Just remember there is no limestone on Mars so no traditional cement. It may be possible to use sulfur as a binder, if you can find some.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/14/2017 02:14 pm
Sulfur is plentiful on Mars. It's often found in a hydrated state, such as gypsum, so you get water at the same time when you process the ore.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/14/2017 04:58 pm
And what will get to mars first. Earth movers(bulldozers) or tunnel borers?
Just put the bigelow modules in the tunnel.
Best to just forget about Bigelow for SpaceX's Mars plans, IMHO. The BFS itself is cheaper for habitable volume than a Bigelow module is, even including all the useless overhead of all the fuel tanks and engines and stuff.

For the record, I'd bet on earth (regolith) movers, first.

Yes, bulldozers first. Need to smooth regolith for landing pads, roads, and structures. Cut and cover for habitats would be an easy way to add protection. If there's not a convenient steep hill or cliff nearby, they'll need a bulldozer to cut into the regolith deep enough for the tunnel borers to get started.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/14/2017 10:52 pm
Bigelow modules seems like they would be the most mass-efficient way to provide habitable volume.

No. That would be tunnels. A good excavator could in principle make an endless interior volume (discounting wear and tear on the equipment). That's the reason behind Musk's new-found interest in Boring Machines.

Lava tubes could be interesting as well. The only problem is that you cannot decide where to put them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/14/2017 11:17 pm
I know everyone keeps going on about lava tubes but I highly doubt they are going to be where you want a base, ie low altitude, near water, no large boulders, horizontal surface, near the equator etc. I think they would be a nice to have but should be not counted on for initial planning,
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 10/15/2017 01:17 am
There exists, somewhere here on NSF a detailed discussion of greenhouses and domes on Mars thread. The take away from my perspective is the lack of consideration of the massive air pressure that Mars sited structures must contain. Air pressure on Mars is effectively zero relative to standard sea level pressure here on Earth. That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft or 20+ tons per square meter. Twenty tons is the mass of a one meter square column of water 20 meters tall on Earth, on Mars where gravity is only about 38 percent of earth, the column would need to be over 52 meters tall.

The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.

1 atm is 10 tonnes per square meter. Skin tension in the vessel membrane, or internal tension elements, can take the pressure. The former works fine up to about 10-15 meters diameter, and the latter can make much larger structures.

Or external tension elements, as in a net outside the membrane.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 10/15/2017 01:49 am
There exists, somewhere here on NSF a detailed discussion of greenhouses and domes on Mars thread. The take away from my perspective is the lack of consideration of the massive air pressure that Mars sited structures must contain. Air pressure on Mars is effectively zero relative to standard sea level pressure here on Earth. That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft or 20+ tons per square meter. Twenty tons is the mass of a one meter square column of water 20 meters tall on Earth, on Mars where gravity is only about 38 percent of earth, the column would need to be over 52 meters tall.

The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.

1 atm is 10 tonnes per square meter. Skin tension in the vessel membrane, or internal tension elements, can take the pressure. The former works fine up to about 10-15 meters diameter, and the latter can make much larger structures.

Or external tension elements, as in a net outside the membrane.

That's possible, the problem is attaching them to something. The ground anchor requirements to hold a dome down around its perimeter are ridiculous. If you're just going around the perimeter it's easier to build a full pressure vessel than to ground anchor. Anchoring throughout the area is much more feasible.

The one thing external cables do help with is that they have a much higher specific strength than the window material, so by using more cable structure to "pull down" a spherical dome into an oblate spheroid to reduce the window surface area you actually save a lot of building mass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/15/2017 01:59 am
Not ridiculous if you drill down deep enough and sideways for the anchors. I mean, Musk is drilling large diameter tunnels. A much, much smaller drill for the anchors would be a lot easier than that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/15/2017 06:25 am
I know everyone keeps going on about lava tubes but I highly doubt they are going to be where you want a base, ie low altitude, near water, no large boulders, horizontal surface, near the equator etc. I think they would be a nice to have but should be not counted on for initial planning

Well, the thread isn't really about start-up settlements, per se. Although we naturally keep coming back to that.

As for lava tubes, and as I mentioned above, they may turn out to be full of water ice, since they should be at a fairly constant low temperature, but accessible to surface air via breaches along the length.

They often have relatively smooth floors, thanks to the final shallow flow of lava ponding in the tube. [Others are a freakin' mess, especially if the walls and roof spall away.] And typically the surrounding terrain is smooth and hard, precisely because it's a former lava-flow.

Instant protection from UV/cosmic-rays, dust-storms, temperature fluctuations, provides a good heat-sink for early habitation, and possibly partly filled with water-ice. What's not to love?



Examples:

Mars Express data mapped onto a perspective view: (Main rille plus two pit-chains. To illustrate the flat surrounding terrain.)

(https://lightsinthedark.files.wordpress.com/2015/03/pit-chains_in_tharsis_large.jpg?w=600&h=338) (https://lightsinthedark.files.wordpress.com/2015/03/pit-chains_in_tharsis_large.jpg?w=600&h=338)

Another example of a pit chain:

(https://qph.ec.quoracdn.net/main-qimg-95587a048193425f9df3ba5b33d7a45d) (https://qph.ec.quoracdn.net/main-qimg-95587a048193425f9df3ba5b33d7a45d)

and with a scale:

(http://blogs.esa.int/caves/files/2015/05/3.-Arsia8.jpg) (http://blogs.esa.int/caves/files/2015/05/3.-Arsia8.jpg)

While the surrounding terrain is flat, given their scale you could conceivably find a site where the floor in a rille or pit is flat enough and wide enough to let you build your landing site inside the rille itself, not far from the entrance of your lava tube based base.

Like this, but a kilometre across:

(http://www.stormchaser.ca/Caves/Hualalai_Volcano_Lava_Tubes/Hualalai_Volcano_Lava_Tubes_07.jpg) (http://www.stormchaser.ca/Caves/Hualalai_Volcano_Lava_Tubes/Hualalai_Volcano_Lava_Tubes_07.jpg)

Aside: The reason why some skylights/rilles are filled with debris and others seem smooth depends on when the collapse happened. If the lava was still flowing inside the tube, it scatters and/or absorbs the debris, then produces the same smooth floor as the rest of the tube when it freezes. But if the collapse occurs after the lava solidifies, the debris just piles up under the skylight.

(http://behindtheblack.com/wp-content/uploads/2015/06/CushingAPCformation.png) (http://behindtheblack.com/wp-content/uploads/2015/06/CushingAPCformation.png)

[Bottom two show the lave still flowing, top two are after it solidifies.]



You can see the similarity in the pit-chain terrain with the Undara lava caves in Queensland. Flat terrain with holes in it. [Fewer trees on Mars, I'd expect.]

(http://phlipvids.com.au/wp-content/uploads/2017/02/Undara-Lava-Tubes-Aerial-1024x768.jpg) (http://phlipvids.com.au/wp-content/uploads/2017/02/Undara-Lava-Tubes-Aerial-1024x768.jpg)

And a section of the Undara lava tube:

(https://s1.at.atcdn.net/wp-content/uploads/2006/04/Undara-Lava-Tubes.jpg) (https://s1.at.atcdn.net/wp-content/uploads/2006/04/Undara-Lava-Tubes.jpg)

Picture the above space, but up to two orders of magnitude bigger. Big enough to hold a small city just going across the tube, and with the tallest buildings on Earth unable to reach the ceiling. (Although on Mars you can build taller.)

I think that fits the criteria of an "Amazing Habitat".



And rille networks on Mars can be ridiculously complex, suggesting the same with lava tubes:

(http://kengarex.com/wp-content/uploads/2017/05/esa-mars-express-pavonis-mons-shield-volcano-central-tharsis-montes-desk-1024.jpg) (http://kengarex.com/wp-content/uploads/2017/05/esa-mars-express-pavonis-mons-shield-volcano-central-tharsis-montes-desk-1024.jpg)

(The above image is one I have to rotate 180° or it depth-reverses and looks like worms. If you get the same, then, depending on your browser, right-click > Rotate Image > Rotate 180°. It should look like channels.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/15/2017 06:26 am
Just to show that lava tubes don't always play nice and provide smooth flat floors:

(http://scp-wiki.wdfiles.com/local--files/scp-1351/moebiuscave1_color.jpg) (http://scp-wiki.wdfiles.com/local--files/scp-1351/moebiuscave1_color.jpg)

(https://c1.staticflickr.com/1/143/378035114_e8ba086742_b.jpg) (https://c1.staticflickr.com/1/143/378035114_e8ba086742_b.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/15/2017 06:26 am
Aside, just because I hadn't seen these ones before.

Mars Reconnaissance Orbiter, looking down into skylights:

(https://ufopress.files.wordpress.com/2011/01/giantsinkholesmars_2.jpg) (https://ufopress.files.wordpress.com/2011/01/giantsinkholesmars_2.jpg)

(http://farm3.static.flickr.com/2279/2104943998_5ced96dee6_o.jpg) (http://farm3.static.flickr.com/2279/2104943998_5ced96dee6_o.jpg)

(https://www.jpl.nasa.gov/images/mro/20101201/pia13650a-43.jpg) (https://www.jpl.nasa.gov/images/mro/20101201/pia13650a-43.jpg)

[edit: No significance to my argument, they're just interesting.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/15/2017 06:27 am
Further aside:

Apparently, NatGeo did a series on colonising Mars that used lava tubes as part of their base. And what did they do...? Filled it with frakkin' domes. Argh. Can't win.

(https://i.pinimg.com/originals/b6/34/b8/b634b8908177227090f7aa1cc4833987.jpg) (https://i.pinimg.com/originals/b6/34/b8/b634b8908177227090f7aa1cc4833987.jpg)



Speaking of NatGeo, on my drunkard's walk, this image came up. It reminds me, given some of the ridiculous formations that we find on Earth, especially in caves, and some of the bizarre land features that the orbital imagers are already finding on Mars, what will we find inside of kilometre wide Mars caves.

(http://cdn.zmescience.com/wp-content/uploads/2011/09/geopicture.jpg) (http://cdn.zmescience.com/wp-content/uploads/2011/09/geopicture.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/15/2017 06:28 am
And because searching for Mars images somehow always leads to UFO-nutter sites,

Sand worm!

(http://dinosaurs-world.com/Clkj_Images/upfile/image/20150225/20150225114056945694.jpg) (http://dinosaurs-world.com/Clkj_Images/upfile/image/20150225/20150225114056945694.jpg)

The spice must flow, Muad'Dib.



I think this is where I stop.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 10/15/2017 07:36 am
In Red, Green & Blue Mars, Kim Stanley Robinson used hollowed out mesa/butte formations.  Tunnel in at ground level and work your way up.  Martian High Rise living.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 10/15/2017 07:48 am
There exists, somewhere here on NSF a detailed discussion of greenhouses and domes on Mars thread. The take away from my perspective is the lack of consideration of the massive air pressure that Mars sited structures must contain. Air pressure on Mars is effectively zero relative to standard sea level pressure here on Earth. That means the structure must restrain 14 lbs/sq-in. That converts to  one ton per sq-ft or 20+ tons per square meter. Twenty tons is the mass of a one meter square column of water 20 meters tall on Earth, on Mars where gravity is only about 38 percent of earth, the column would need to be over 52 meters tall.

The habitats on mars must be very, very deep under the surface to avoid blowout from the internal air pressure.

1 atm is 10 tonnes per square meter. Skin tension in the vessel membrane, or internal tension elements, can take the pressure. The former works fine up to about 10-15 meters diameter, and the latter can make much larger structures.

Or external tension elements, as in a net outside the membrane.

That's possible, the problem is attaching them to something. The ground anchor requirements to hold a dome down around its perimeter are ridiculous. If you're just going around the perimeter it's easier to build a full pressure vessel than to ground anchor. Anchoring throughout the area is much more feasible.

The one thing external cables do help with is that they have a much higher specific strength than the window material, so by using more cable structure to "pull down" a spherical dome into an oblate spheroid to reduce the window surface area you actually save a lot of building mass.

I was thinking more along the line of having the net totally surround the membrane.  Be it spheroid or cylindrical, the net would be made to the same shape and therefore evenly restrain the internal pressure.  Anchor points would then only have to stop it blowing away in those ferocious Martian winds.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 10/15/2017 09:28 am
If you have pressurised habitats inside a dome, then you can get away with pressurising the dome a lot lower. 0.07atm is above the Armstrong limit, so no need for a pressure suit "outside", and the triple point of water is ~40°C, so you can have lakes etc. A breathing mask would still be required. External pressure at the bottom of a deep canyon such as Melas Chasma should be ~0.01atm.

For a minimally breathable atmosphere you could probably get away with ~0.2atm.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/15/2017 10:56 am
Paul451

Great post! To my eyes those features look more like they are associated by groundwater moving, however, I found a paper that links pit chains to a certain type of faulting.

Distribution, morphology, and origins of Martian pit crater chains (http://onlinelibrary.wiley.com/doi/10.1029/2004JE002240/full)

Label for figure
Schematic drawing illustrating that pit volume is a function of (a) the depth of the dilational fault segment, (b) increased displacement along the fault or (c) the thickness of the overlying unconsolidated material.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 10/15/2017 11:06 am
Pits can also be caused by CO2 ice sublimation on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 10/15/2017 02:54 pm
And because searching for Mars images somehow always leads to UFO-nutter sites,

Sand worm!

(http://dinosaurs-world.com/Clkj_Images/upfile/image/20150225/20150225114056945694.jpg) (http://dinosaurs-world.com/Clkj_Images/upfile/image/20150225/20150225114056945694.jpg)

The spice must flow, Muad'Dib.



I think this is where I stop.

Now we know how SpaceX will fund Mars colonization. House Musk will control the spice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 10/15/2017 02:59 pm
Is there a map or sets of coordinates for known Martian lava tubes, and do we have any evidence that there is plenty of the critical water resource nearby?
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/15/2017 03:15 pm
I think the water ice and the lava tubes are in different places...

Water ice is at high latitudes and low altitudes, features possibly associated with lava tubes are at low latitudes and high altitudes - specifically the tharsis bulge and the big volcanoes there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/15/2017 04:12 pm
Map from a paper on Lava tubes.  Dark blue dots are tubes.

http://marsed.asu.edu/sites/default/files/msip_reports/Martian%20lava%20tubes.pdf

And as a little decoration, my take on an elliptical dome
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/15/2017 04:21 pm
Map from a paper on Lava tubes.  Dark blue dots are tubes.

http://marsed.asu.edu/sites/default/files/msip_reports/Martian%20lava%20tubes.pdf

And as a little decoration, my take on an elliptical dome
Oh, wow, a low altitude lava tube! That might actually be worth checking out. The others are too high altitude, which is bad for a bunch of reasons.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 10/15/2017 04:26 pm
Water may be more widespread than those lower resolution maps suggest.

Equatorial locations of water on Mars: Improved resolution maps based on Mars Odyssey Neutron Spectrometer data (http://www.sciencedirect.com/science/article/pii/S0019103516306029?via%3Dihub)

Quote
We present a map of the near subsurface hydrogen distribution on Mars, based on epithermal neutron data from the Mars Odyssey Neutron Spectrometer. The map’s spatial resolution is approximately improved two-fold via a new form of the pixon image reconstruction technique. We discover hydrogen-rich mineralogy far from the poles, including  ∼10 wt.% water equivalent hydrogen (WEH) on the flanks of the Tharsis Montes and  >40 wt.% WEH at the Medusae Fossae Formation (MFF). The high WEH abundance at the MFF implies the presence of bulk water ice. This supports the hypothesis of recent periods of high orbital obliquity during which water ice was stable on the surface. We find the young undivided channel system material in southern Elysium Planitia to be distinct from its surroundings and exceptionally dry; there is no evidence of hydration at the location in Elysium Planitia suggested to contain a buried water ice sea. Finally, we find that the sites of recurring slope lineae (RSL) do not correlate with subsurface hydration. This implies that RSL are not fed by large, near-subsurface aquifers, but are instead the result of either small ( < 120 km diameter) aquifers, deliquescence of perchlorate and chlorate salts or dry, granular flows.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 10/15/2017 04:41 pm
Interesting, but needs to be taken with a pinch of salt. (groan :) )

"Our result is consistent with the lower member of the MFF containing ice rich material, which lends weight to the theory that, at least part of, the Medusae Fossae Formation (MFF) is a polar layered-like deposit. Salt hydrates could also explain the observations as they have up to 50 wt.% water equivalent hydrogen, but their stability in the Martian regolith has not been demonstrated (Bish et al., 2003). No detections of hydrated minerals within the MFF are reported in either CRISM or OMEGA data sets (Carter et al., 2013)."

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/16/2017 02:24 am
I found a paper that links pit chains to a certain type of faulting.
Distribution, morphology, and origins of Martian pit crater chains (http://onlinelibrary.wiley.com/doi/10.1029/2004JE002240/full)

Rilles associated with faulting has also been suggested as a mechanism on the moon. But rilles and pits associated with tunnels seems to be limited to lava tubes.

Note that the paper is talking about a different type of pit chain.

See the differences between their type and what I showed:

[Theirs]

(http://onlinelibrary.wiley.com/store/10.1029/2004JE002240/asset/image_n/jgre1843-fig-0001.png?v=1&s=3d0da88267cf3d1da5d97623443c4c3221903951) (http://onlinelibrary.wiley.com/store/10.1029/2004JE002240/asset/image_n/jgre1843-fig-0001.png?v=1&s=3d0da88267cf3d1da5d97623443c4c3221903951)

(http://onlinelibrary.wiley.com/store/10.1029/2004JE002240/asset/image_n/jgre1843-fig-0009.png?v=1&s=197f7f56e96502ec6d9574e0878b052dd94695e2) (http://onlinelibrary.wiley.com/store/10.1029/2004JE002240/asset/image_n/jgre1843-fig-0009.png?v=1&s=197f7f56e96502ec6d9574e0878b052dd94695e2)



[Mine]

(https://qph.ec.quoracdn.net/main-qimg-95587a048193425f9df3ba5b33d7a45d) (https://qph.ec.quoracdn.net/main-qimg-95587a048193425f9df3ba5b33d7a45d)

(https://ufopress.files.wordpress.com/2011/01/giantsinkholesmars_2.jpg) (https://ufopress.files.wordpress.com/2011/01/giantsinkholesmars_2.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/16/2017 02:28 am
Martian lava tubes, and do we have any evidence that there is plenty of the critical water resource nearby?

If you mean my idea of water ice preferentially collecting inside the tubes, then no. Zero data. It's just something I'm proposing from first principles. (I have seen other suggestions that lava tubes might collect melt-water run off, I haven't seen anyone suggest the same mechanism I'm proposing.)

Providing evidence would require pretty close examination, it's not something you could detect from orbit. (Too localised for deep scans that map broad areas, too hidden for fine scans that map surface composition.) But if my hypothesised effect exists, it should work in any lava tube, so a single robotic visit to a single site should prove/disprove the idea; and they are generally interesting features anyway.

Once it's cheap to get to Mars, throwing low-cost and relatively mass-produced robotic rovers around should become more common. In the window between cheap transport and human settlement, someone will hopefully have a look.

If it exists, then there's multiple sites with megatonnes of fairly pure ice (not hydrated regolith, or frozen aquifers, or buried glaciers) in an easily mined form (probably as firn), in a location that's extremely convenient for settlement (a pre-existing tunnel through a layer of hard basalt.)



I think the water ice and the lava tubes are in different places...
Water ice is at high latitudes and low altitudes, features possibly associated with lava tubes are at low latitudes and high altitudes - specifically the tharsis bulge and the big volcanoes there.

Again, my suggestion of a link between lava tubes and water is based on the temperature inside the tubes, it is unrelated to the broad distribution of hydrogen in the regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: vaporcobra on 10/16/2017 04:07 am
And what will get to mars first. Earth movers(bulldozers) or tunnel borers?
Just put the bigelow modules in the tunnel.
Best to just forget about Bigelow for SpaceX's Mars plans, IMHO. The BFS itself is cheaper for habitable volume than a Bigelow module is, even including all the useless overhead of all the fuel tanks and engines and stuff.

For the record, I'd bet on earth (regolith) movers, first.

Yes, bulldozers first. Need to smooth regolith for landing pads, roads, and structures. Cut and cover for habitats would be an easy way to add protection. If there's not a convenient steep hill or cliff nearby, they'll need a bulldozer to cut into the regolith deep enough for the tunnel borers to get started.

If SpaceX or a separate company is already going to have to design their own heavy machinery from scratch to optimize for mass, having separate machines is wasteful. I'd expect that wherever possible, a modular base with swappable tools will be preferred. 1/3rd Earth gravity will also spice things up considerably.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/07/2017 06:36 pm
If you have pressurised habitats inside a dome, then you can get away with pressurising the dome a lot lower. 0.07atm is above the Armstrong limit, so no need for a pressure suit "outside", and the triple point of water is ~40°C, so you can have lakes etc. A breathing mask would still be required. External pressure at the bottom of a deep canyon such as Melas Chasma should be ~0.01atm.

For a minimally breathable atmosphere you could probably get away with ~0.2atm.

You could have pressurized habitats inside a partially pressurized dome, but the bigger question is why would one want to do that... it seems that on an apples-to-apples basis, partial-pressure domes provide less habitable volume for a higher lifetime cost and more system complexity. Of course, a partially pressurized dome would be good for a greenhouse.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/07/2017 06:49 pm
If you have pressurised habitats inside a dome, then you can get away with pressurising the dome a lot lower. 0.07atm is above the Armstrong limit, so no need for a pressure suit "outside", and the triple point of water is ~40°C, so you can have lakes etc. A breathing mask would still be required. External pressure at the bottom of a deep canyon such as Melas Chasma should be ~0.01atm.

For a minimally breathable atmosphere you could probably get away with ~0.2atm.

You could have pressurized habitats inside a partially pressurized dome, but the bigger question is why would one want to do that... it seems that on an apples-to-apples basis, partial-pressure domes provide less habitable volume for a higher lifetime cost and more system complexity. Of course, a partially pressurized dome would be good for a greenhouse.

See the second post in this thread :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/07/2017 07:16 pm
a partially pressurized dome would be good for a greenhouse.

Not really. I forget the reference, it's probably somewhere in the Scaling Ag thread, but in reduced pressure environments, the critical limits (ie, the minimums and maximums) tend to approach each other; resulting in the plants becoming much "fussier" about their environment.

(Also, "dome". Reduced pressure merely makes a bad idea easier; it doesn't turn it into a good idea.)

[Edit: By "minimums and maximums", I mean the level of something that allows growth vs the level that causes toxicity. For example, plants have a minimum amount of CO2 required for growth, any less and they become dormant. But they also have a maximum level, beyond which the leaves will acidify and "burn". The former is related to partial pressure, the latter to relative gas percentage. Hence, when you lower the air pressure, the percentage of CO2 required to stay above the minimum partial pressure for growth increases; drop the pressure enough and it will exceed the percentage that causes acidification of the plant tissues. Similar things happen with other requirements, such as water. As you lower the air pressure, plants require more water to achieve the same growth. Drop the pressure enough, and plants enter their drought state regardless of how much water is available.]

[[To a certain extent, plants are more delicate than people.]]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2017 02:28 am
A dome is good for multiple reasons. First, it gives you pressure vessel redundancy. A big increase in safety.

Second: it can be pretty cheaply made, lightweight and makes construction of stuff inside a LOT easier as you can use nearly unmodified Earthside equipment.

Third, and depending on the makeup of the atmosphere inside, it greatly increases living space and reduces the feeling of claustrophobia.

fourth: it's cool. We're not going to Mars for our health, we're going because it's cool. So gotta maximize that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/08/2017 03:19 am
A dome is good for multiple reasons. First, it gives you pressure vessel redundancy. A big increase in safety.

Except domes aren't pressure vessels, that's their problem.

I'm not arguing against the idea of using a partial pressure environment to allow large volume at a lower cost (it might be useful, it might not, that's a different debate), just that domes are a really, really stupid way of doing it.

Second: it can be pretty cheaply made, lightweight

Not if you actually want to hold an atmosphere (even a partial one), then they need more construction to hold them in place than any proper pressure vessel. Making them more expensive, complex and fragile than alternatives.

You can force domes to work, by creating over-engineered anchors, by sufficiently sealing the floor, by reinforcing the rim, etc etc. For what? To expensively gain the same volume that could be vastly more easily gained by using a proper pressure vessel.

The only reason people suggest domes is that, like you no matter how many times we go over this, they always have this image in their heads that domes are "easy". Just throw together a few panels, or a plastic sheet, add some air, and viola! instant Martian/Lunar habitat. And, like you, no matter how many times we go into the details of why domes are just the dumbest concept for pressure-vessels, somehow as soon as the subject changes, they go back to that mental image of the easy dome on Mars or the Moon. It's almost like a very specific anterograde-amnesia (where people can't form new memories.)

Can't you guys get a tattoo or something? Keep a special notebook? Have a little macro pop-up on your computer wherever you type d-o-m-e, with a quick summary of why domes are stupid, and a counter showing how many times it's had to do that?
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/08/2017 03:58 am
I learn just to translate "dome" in my head to one of the various dome-like substitutes that seem acceptable to me. It could be a buried sphere or oblate sphere, it could be a dome anchored to an entire underground city. I think it is quite likely that "domes" is exactly what it will look like from the surface.

Unlike the Moon vs Mars debate, there is not even the theoretical possibility of getting stuck in "dome boondoggle", so it doesn't bother me that much.

It is only a pity that newbies who have not seen the threads on this may be left with the impression that you can put up a dome just like pitching a tent, and won't get a feel for the huge 5-10 ton/m2 pressure that will be dealt with one way or another.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/08/2017 04:14 am
It is only a pity that newbies who have not seen the threads on this may be left with the impression that you can put up a dome just like pitching a tent

Robotbeat, and others who keep bringing them up, are not newbies. And they don't mean "a proper pressure-vessel of deceptively dome-like appearance due to its placement".
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/08/2017 04:17 am
A dome is good for multiple reasons. First, it gives you pressure vessel redundancy. A big increase in safety.

Except domes aren't pressure vessels, that's their problem.

I'm not arguing against the idea of using a partial pressure environment to allow large volume at a lower cost (it might be useful, it might not, that's a different debate), just that domes are a really, really stupid way of doing it.

Second: it can be pretty cheaply made, lightweight

Not if you actually want to hold an atmosphere (even a partial one), then they need more construction to hold them in place than any proper pressure vessel. Making them more expensive, complex and fragile than alternatives.

You can force domes to work, by creating over-engineered anchors, by sufficiently sealing the floor, by reinforcing the rim, etc etc. For what? To expensively gain the same volume that could be vastly more easily gained by using a proper pressure vessel.

The only reason people suggest domes is that, like you no matter how many times we go over this, they always have this image in their heads that domes are "easy". Just throw together a few panels, or a plastic sheet, add some air, and viola! instant Martian/Lunar habitat. And, like you, no matter how many times we go into the details of why domes are just the dumbest concept for pressure-vessels, somehow as soon as the subject changes, they go back to that mental image of the easy dome on Mars or the Moon. It's almost like a very specific anterograde-amnesia (where people can't form new memories.)

Can't you guys get a tattoo or something? Keep a special notebook? Have a little macro pop-up on your computer wherever you type d-o-m-e, with a quick summary of why domes are stupid, and a counter showing how many times it's had to do that?

Domes are great pressure vessels.

Look, I remember that long thread arguing about anchors, etc.

All amateurish and arm-wavey. Didn't convince me in the least.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 11/08/2017 09:51 pm
Tattoos? Tattoo this somewhere handy. Be excellent to each other. Snark isn't needful. Thanks
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/09/2017 03:19 am
Air-supported structures are used often for sporting events especially in northern climates during the winter.

They normally operate at 0.35psi. Mars surface pressure at Hellas Basin is 0.18psi. The Armstrong Limit is 0.91psi, so even if you're just building stuff or growing plants, you'd want more than that. Probably more like 1.75psi to give a margin of safety. That's still closer to air-supported structures on Earth than it is to a full sea level pressure station module. Domes are feasible.

Some leakage is fine for some purposes, like growing plants or preparing buildings.

Instead of white plastic, you could make them using ETFE so they're clear.

With Zylon or carbon fiber cables, you could build a very large dome for relatively low mass (about 1000 tons for a square kilometer and 30 meter height, with anchors placed in the middle as well to reduce structural mass). Deep, deadman-style anchors wouldn't be too hard, either (with anchors sunk in a redundant fashion). Large blowers could keep them inflated. This would make constructing buildings way easier. And eventually you could also put a liner down to reduce leakage rates to arbitrarily low levels (so you can get rid of the blowers) and fill it with breathable air.

Might also be a good way to mine a glacier or minerals.

It'd need site prep around the perimeter, perhaps using sandbags and the like, to get a good seal. About 3 meters thick and tall sand tube around the perimeter with soil piled up a few meters tall on both sides should give a good seal. That would be in addition to the deep deadman anchors and anchors placed interspersed in the middle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 11/09/2017 07:49 am
What would a blower built to operate on Mars and generate sufficient pressure difference looks like? The atmosphere is pretty thin ... even though you wouldn't need much added pressure, it seems like the thin atmosphere will still make this an interesting engineering challenge.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/09/2017 04:49 pm
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1458696;image)

Uh, those black structures are the intake fans, running at a continuous 40kW each. That suggests a bit more than "some leakage". [edit: Apparently the airflow inside the structure is around 3mph. Suggesting it cycles it's own volume approximately every 2 minutes. In other words, without the continuous airflow, it would empty in 2 minutes. And that's with a pressure explicitly only the amount needed to balance the weight of the skin, providing no additional force.]

And yes, you could drill into rock and anchor the edges down, then add a sealed floor, and otherwise try to turn a non-pressure-vessel into a badly designed pressure-vessel. For what purpose? Just design a proper, fit-for-purpose, pressure-vessel from the start. Why the continued insistence on domes?
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/09/2017 05:12 pm
(The pressure used in those kinds of structures is explicitly the amount needed to balance the weight of the skin, providing no additional force. It's very deliberately as low as they can get away with.)

You can supplement with other support as necessary. All it needs to do is trap some atmosphere and the moisture. It's my belief that the best way to terraform mars is to create a greenhouse effect. And the best way to create a greenhouse effect is to build a greenhouse.

For what purpose? Just design a proper, fit-for-purpose, pressure-vessel from the start.

Then you're just stuck in an ISS on mars. Proper pressure vessels are too small.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/09/2017 05:29 pm
For what purpose? Just design a proper, fit-for-purpose, pressure-vessel from the start.
Then you're just stuck in an ISS on mars. Proper pressure vessels are too small.

Is that why people are so obsessed with domes? You think the only alternative is an aluminium can?

If the material of your dome is capable of holding ten-tonnes-per-square-metre of atmospheric pressure as a dome, it's more than capable of doing do when properly shaped. It's the same material. The only difference is that you aren't starting with the wrong structure and then trying to clumsily force it to do the job.

[edit:

The pressure used in those kinds of structures is explicitly the amount needed to balance the weight of the skin,
You can supplement with other support as necessary.

Restraint, not support. It doesn't take much pressure to hold up a skin of plastic, the issue is that even low pressure is a) leaking continuously and b) trying to tear the dome off the ground. And that the force tearing the dome off the ground increases with the square of diameter, while the circumference increases linearly, so the force per metre of rim increase in proportion with the size of the dome. A large dome, even at low pressure, will produce an extraordinary amount of force.

For example, say you had a partial-pressure CO₂-only dome a kilometre across to cover your base-proper. Say just 0.2 atm, drawn from raw Mars atmosphere via big fans. Area of the dome depends on the height; at 200m peak, we have a surface area of 900,000m², and a cross sectional area of 780,000m². (At 100m peak, surface area drops to 800,000m², at 300m peak, ~1e7m². So the 200m case is a reasonable value to work with for a back-of-the-envelope.)

The pressure trying to lift the dome vertically is around 7.8 million tonnes of force. Additionally there's an outward pressure on the rim of around 1.2m tonnes of force. The total 9 million tonnes of force ends up concentrated on the 3km rim, producing nearly 2,800 tonnes of force per metre, with 2,500 tonnes of that straight up (or 1.6 million lbs per foot, if you prefer, or 810 US long-tons per foot.) We'll ignore the outward force and focus on the vertical component.

If you tried to anchor the dome down by mass alone, 2,500 tonnes of force requires 6,500 tonnes of mass. Per metre. As regolith, you're looking at 2-3,000 cubic metres of regolith every metre, so a 50 metres high, 50 metres deep solid wall running all the way around the dome. Using rock drops that to a 40x40m wall. (You can't go much longer than high, or the near end will simply lift up anyway.)

That's just to hold it down. With no reserve.

The dome has a volume of ~83 million cubic metres. If you can get the rate of air-loss down to just 1% of Robotbeat's example, then you will need to replace that volume every 2.5-3 hours. Using figures from large industrial fans (around 6m³/s/kW), gives you a power requirement just to replace the leaking atmosphere of around 1.5MW, continuously. That assumes both excellent sealing against air-loss, and no loss of fan efficiency from pumping near-vacuum Mars air; and both assumptions seem unlikely.]

end-edit]
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/09/2017 05:36 pm
Is that why people are so obsessed with domes? You think the only alternative is an aluminium can?

Well yes, when trying to stay within the confines of hard sci-fi.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/09/2017 06:08 pm
Is that why people are so obsessed with domes? You think the only alternative is an aluminium can?
Well yes, when trying to stay within the confines of hard sci-fi.

[edit: snipe deleted]

What magic properties of a dome do you think allows it to hold pressure in a way that a closed structure (like a spheroid or rounded-end tube) can't?
Title: Re: Envisioning Amazing Martian Habitats
Post by: ejb749 on 11/09/2017 06:31 pm
I was reading earlier in this thread that the ITS can only land in certain areas of Mars, ie. not the polar regions.

With the BFR being presented as a 30 minute to anywhere on earth transport, wouldn't the BFS also be able to do 10 minute to anywhere on Mars transport? (Mars being 1/3 the size of Earth).

If so, you could land, refuel, and then hop to anywhere on Mars. 

This would give you an initial landing site with re-fueling capability, and a second site in a polar region where people would actually work and live.



Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/09/2017 06:42 pm
[Lars, how is snark not justified here? (Or at least facepalming jaw-dropping disbelief, which comes across as snark in text.)]

SS,
What magic properties of a dome do you think allows it to hold pressure in a way that a closed structure (like a spheroid or rounded-end tube) can't?

Sorry for my lack of imagination. Living areas probably would need to be proper pressure vessels. May be something like this could be scaled up on mars.
https://www.youtube.com/watch?v=WKfID-i41sc

My idea of "domes" is really just covering large areas with plastic to create a large warmth and moisture trap with low air pressure, but high humidity that could sustain liquid water (brine) and growth of algae. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/09/2017 06:51 pm
in a polar region where people would actually work and live.

Why? It's horrible in the winter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/09/2017 07:36 pm
If the material of your dome is capable of holding ten-tonnes-per-square-metre of atmospheric pressure as a dome, it's more than capable of doing do when properly shaped. It's the same material. The only difference is that you aren't starting with the wrong structure and then trying to clumsily force it to do the job.

Holding pressure forces is actually quite easy with modern fibers. 15 tonnes of Kevlar or Spectra will make a 100 meter half-sphere holding 1 atmosphere. The problem, as you noted, is the 80,000 tonnes of force trying to lift the half-sphere off the ground. However, with internal high tensile fiber cabling and a sealed structural floor it's not difficult to make a proper pressure vessel that's dome shaped and feels very open. And that's with no ground anchors or regolith ballast.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/09/2017 08:46 pm
Tunnels, guys. What's so difficult to understand about that?

The "buildings" are already there, on Mars. Pressure-, radiation- and meteorite-proof. They just need to be hollowed out!
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/09/2017 08:51 pm
For example, say you had a partial-pressure CO₂-only dome a kilometre across to cover your base-proper. Say just 0.2 atm ... height; at 200m peak

That's too amazing for my envisioning power. My vision of the fancy Mars biodome is more or less on that stock photo above. Positive pressure, but barely over ambient, leaky. It would surround the pressurized colony (could be tin cans or other pressure vessels) which dumps its waste heat and gasses into it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ejb749 on 11/09/2017 09:24 pm
in a polar region where people would actually work and live.

Why? It's horrible in the winter.

I'd rather be where the water is.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/09/2017 09:31 pm
Especially if you need the hydrogen in the water to get back to Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/09/2017 09:40 pm
I'd rather be where the water is.

Plenty of water is even near the equator.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/09/2017 10:49 pm
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1458696;image)

Uh, those black structures are the intake fans, running at a continuous 40kW each. That suggests a bit more than "some leakage". [edit: Apparently the airflow inside the structure is around 3mph. Suggesting it cycles it's own volume approximately every 2 minutes. In other words, without the continuous airflow, it would empty in 2 minutes. And that's with a pressure explicitly only the amount needed to balance the weight of the skin, providing no additional force.]

And yes, you could drill into rock and anchor the edges down, then add a sealed floor, and otherwise try to turn a non-pressure-vessel into a badly designed pressure-vessel. For what purpose? Just design a proper, fit-for-purpose, pressure-vessel from the start. Why the continued insistence on domes?
Oh please.

Greenhouses require lots of ventilation to keep cool. You don't need that on Mars since Mars is cold.

And I have no idea where you get the idea that an inflated dome isn't a pressure vessel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/10/2017 12:56 am
And I have no idea where you get the idea that an inflated dome isn't a pressure vessel.

That's the crux of this misunderstanding. One side believes the ground can act as the bottom half of a pressure vessel and the other side believes it would leak too much. I think we can all agree that the engineering issues can be solved, whatever that solution might be.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/10/2017 07:05 am
And I have no idea where you get the idea that an inflated dome isn't a pressure vessel.

That's the crux of this misunderstanding. One side believes the ground can act as the bottom half of a pressure vessel and the other side believes it would leak too much. I think we can all agree that the engineering issues can be solved, whatever that solution might be.

I really can't see the problem in sealing the ground to be airtight.

Edit: That said, my gut feeling is that a design with self containing forces is safer than a design that depends on ground anchors, which must never fail, considering there might be undetected ground faults that one day may give. At least the anchoring has to be done with a very high safety factor.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/10/2017 07:07 am
And I have no idea where you get the idea that an inflated dome isn't a pressure vessel.
That's the crux of this misunderstanding. One side believes the ground can act as the bottom half of a pressure vessel and the other side believes it would leak too much.

No, the issue is that people suggest domes because they think they are "cheaper, lighter, lower risk, easier construction" (to paraphrase Robotbeat's justification just recently.) Just pop up a plastic sheet or geodesic shell, pump in some air, et voila, instant large habitat. Enclose a city, enclose a crater. Hell, arch over a whole valley. A thousand artists' impressions can't be wrong.

And then some pedantic git like me points out the issues, and six pages of arguments and several mod-warnings later, the dome-advocate -- in order to hold onto the concept of "a dome on Mars" -- has added deep-drilled rock anchors every metre around the circumference, a sealed floor, extra lateral reinforcing around the rim, etc etc. And yes, you can, with great effort, create a dome on Mars. Mazel tov. And... what was the point again? What was the supposed advantage over a proper pressure vessel?

That's the crux.

People imagine domes on Mars (or the moon) because they are picturing... well, a giant tent. Just pop it on the surface, inflate and done. At most, maybe a few "pegs" along the sides. But they continue to defend the concept long after the effort required to "have a dome" exceeds the complexity/difficulty/risk of virtually any proper pressure-vessel. And later they continue to claim, to believe, that the dome is easier/cheaper/lower-risk. And so the process starts all over again.

[edit: tyopes typos.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Semmel on 11/10/2017 10:35 am
Paul, a question.. what would a proper pressure vessel be like? And can you make one with a transparent top for plant growth and human sanity? One with preferably one or multiple flat floors (for living space and plant growth)? What size could it be, realistically?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/10/2017 10:56 am
If the aim is to preserve human sanity then tunnels are still not a problem. You can easily imagine a tunnel system with some small "Cupola"-like domes popping up above the surface. They'd be a good place to go in the spare time of our intrepid tunnel-borers...
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/10/2017 11:49 am
Paul, a question.. what would a proper pressure vessel be like? And can you make one with a transparent top for plant growth and human sanity? One with preferably one or multiple flat floors (for living space and plant growth)? What size could it be, realistically?

Here is one option:

Thusly?

Or alternatively:

And as a little decoration, my take on an elliptical dome

Various shapes here:
https://en.wikipedia.org/wiki/Pressure_vessel

One of my favorites:
https://www.nasa.gov/content/liquid-hydrogen-the-fuel-of-choice-for-space-exploration
(a sphere)
Personally I think that is a very straightforward and pretty approach. The lower side could be divided into levels with nice down-looking windows, like at an airport.. or you could have external mirrors to reflect more light in and grow food there. The top level may contain vegetation, but mainly to provide a pleasant environment.

A swimming pool could provide shielding for levels beneath and store heat to balance night and day temperatures.

Another nice option could be a tower. Lower levels would have lots of shielding, and you would be able to see the horizon from many levels, which is more important than seeing the sky from one IMO.

I don't think there is any real limit on size. Bigger pressure vessels need thicker walls but overall mass to volume is constant regardless of size.

I also favour a cellular approach that could be built up over time. Cells could have walls taken out to create interesting shaped, winding and straight volumes, while still having multiple levels of redundancy.

This has all be discussed somewhere, possibly on this thread. There was another thread about Musk's mention of geodesic domes that speculated on other geometric shapes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 11/10/2017 05:24 pm
in a polar region where people would actually work and live.

Why? It's horrible in the winter.

Worse yet if the source of electricity is solar, polar colonies are pretty much out unless you're into really HUGE solar farms.  Even mid northern latitudes rich with water ice suffer from reduced insolation in the LONG winters.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 11/10/2017 06:37 pm
Later, history would record that the first Martian wars began over if domes were or were not pressure vessels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 11/10/2017 07:08 pm
NSF discussions are normally technical in nature. In that vein, consider the mass of a pressure vessel, or Dome if one is to insist that domes are pressure vessels.

https://en.wikipedia.org/wiki/Pressure_vessel#Scaling (https://en.wikipedia.org/wiki/Pressure_vessel#Scaling)

Quote
Spherical vessel

For a sphere, the minimum mass of a pressure vessel is

    M = 3 2 P V ρ σ {\displaystyle M={3 \over 2}PV{\rho \over \sigma }} M={3 \over 2}PV{\rho \over \sigma },

where:

    M {\displaystyle M} M is mass, (kg)
    P {\displaystyle P} P is the pressure difference from ambient (the gauge pressure), (Pa)
    V {\displaystyle V} V is volume,
    ρ {\displaystyle \rho } \rho is the density of the pressure vessel material, (kg/m^3)
    σ {\displaystyle \sigma } \sigma is the maximum working stress that material can tolerate. (Pa)[12]

Other shapes besides a sphere have constants larger than 3/2 (infinite cylinders take 2), although some tanks, such as non-spherical wound composite tanks can approach this.

With this, the surface area can be calculated for your preferred volume using S/V = 3/R or S = 3 V / R. Now thickness can be calculated as t = M/rho S. Continuing in this vein I get a formula for thickness, t =P*R/2 *sigma. Make sure that you derive this formula for yourself before you use it, I am notorious for making "minor" errors in derivations.

Many kinds of polyethylene are known, with most having the chemical formula (C2H4)n. Seems like the raw material is available on Mars. But the working stress is low. Even so, my formula applied to a sphere with a 500-meter radius made of HDPE, containing one psi pressure would only need to be 6 tenths of an inch thick if pressurized to yield stress.

Digging out the 500-meter deep pit to bury half the sphere may be a challenge, I suggest a room and tunnel system where the tunnels are 3-meter diameter cylinders laid out on the surface, and the rooms are 5 to 15-meter diameter spheres. Fifteen-meter spheres make for very big rooms but are admittedly not city-sized.

Digging a 2-1/2 meter deep pit to bury a 5-meter sphere is not nearly so tricky as trying to anchor a 5-meter dome then sealing the soil to be airtight. Remember, whether the dome is a habitat or a greenhouse, the oxygen content is quite valuable and you don't want it leaking away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/10/2017 07:47 pm
Worse yet if the source of electricity is solar, polar colonies are pretty much out unless you're into really HUGE solar farms.

Farm size won't matter in the polar night.

I'd rather be where the water is.

Plenty of water is even near the equator.

It actually bothers me. Huge amounts of water are necessary for plans that involve fueling rockets on mars. But it's utterly unclear to me where it comes from. Has this been convincingly addressed somewhere? Is it pulled form the dry air or squeezed from the dry sand or is it supposed to be found in a cave?

Google image search gives several differing versions of mars water maps, all seem to be based on Mars Oddyssey data. Is it reliable? I mean its based on converting some sorts of radiation counts into regolith water content, a process I assume relies on many assumptions. How deep does it see? Do the rovers confirm it? Assuming it's all correct and the gold standard of knowledge on the subject - how much is enough? 2%, 10%, 80% water content?

So many questions. Is it my ignorance or is there a huge and critical vacuum of knowledge here? I mean, the visions of amazing habitats should be quite different whether they are supposed to be the equator or the pole.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/10/2017 08:18 pm
NSF discussions are normally technical in nature. In that vein, consider the mass of a pressure vessel, or Dome if one is to insist that domes are pressure vessels.

https://en.wikipedia.org/wiki/Pressure_vessel#Scaling (https://en.wikipedia.org/wiki/Pressure_vessel#Scaling)

Quote
Spherical vessel

For a sphere, the minimum mass of a pressure vessel is

    M = 3 2 P V ρ σ {\displaystyle M={3 \over 2}PV{\rho \over \sigma }} M={3 \over 2}PV{\rho \over \sigma },

where:

    M {\displaystyle M} M is mass, (kg)
    P {\displaystyle P} P is the pressure difference from ambient (the gauge pressure), (Pa)
    V {\displaystyle V} V is volume,
    ρ {\displaystyle \rho } \rho is the density of the pressure vessel material, (kg/m^3)
    σ {\displaystyle \sigma } \sigma is the maximum working stress that material can tolerate. (Pa)[12]

Other shapes besides a sphere have constants larger than 3/2 (infinite cylinders take 2), although some tanks, such as non-spherical wound composite tanks can approach this.

With this, the surface area can be calculated for your preferred volume using S/V = 3/R or S = 3 V / R. Now thickness can be calculated as t = M/rho S. Continuing in this vein I get a formula for thickness, t =P*R/2 *sigma. Make sure that you derive this formula for yourself before you use it, I am notorious for making "minor" errors in derivations.

Many kinds of polyethylene are known, with most having the chemical formula (C2H4)n. Seems like the raw material is available on Mars. But the working stress is low. Even so, my formula applied to a sphere with a 500-meter radius made of HDPE, containing one psi pressure would only need to be 6 tenths of an inch thick if pressurized to yield stress.

Digging out the 500-meter deep pit to bury half the sphere may be a challenge, I suggest a room and tunnel system where the tunnels are 3-meter diameter cylinders laid out on the surface, and the rooms are 5 to 15-meter diameter spheres. Fifteen-meter spheres make for very big rooms but are admittedly not city-sized.

Digging a 2-1/2 meter deep pit to bury a 5-meter sphere is not nearly so tricky as trying to anchor a 5-meter dome then sealing the soil to be airtight. Remember, whether the dome is a habitat or a greenhouse, the oxygen content is quite valuable and you don't want it leaking away.
The idea is to use a thin layer (or double layer most likely) and then reinforce with a net or grid of cables. That's what large pressure stabilized domes look like. You can use very strong material for the cables; the thin material doesn't need to be particularly strong; other qualities like transparency are equally important.

For the cables, you would use something strong and lightweight. Strength is probably more important than weight if you're building them on Mars.

For stuff brought from Earth, you'd use Zylon or carbon fiber or similar. For ISRU, instead of the HDPE form of polyethylene, you would want UHMWPE, which has a very high strength to weight ratio. You could also use basalt fiber (basalt is common on Mars, and it's stronger than fiberglass) or steel/iron.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/10/2017 09:19 pm
Google image search gives several differing versions of mars water maps, all seem to be based on Mars Oddyssey data. Is it reliable? I mean its based on converting some sorts of radiation counts into regolith water content, a process I assume relies on many assumptions. How deep does it see? Do the rovers confirm it? Assuming it's all correct and the gold standard of knowledge on the subject - how much is enough? 2%, 10%, 80% water content?

I can't really provide answers, but I can add to your questions. The data is from hydrogen, not water. So it is converted into "water equivalent" units. (You see %WE in the labels sometimes.) The variation in maps presumably comes from assumptions about the amount of hydrogen present in the minerals at that part of Mars, which depends on assumptions/data about the types of materials.

The same techniques are used to monitor changing moisture levels in soils and plants and forests on Earth. But your assumptions about the site make a big difference in your interpretation of the data. That is, it's very good for telling you the thickness of the paint on the wall, provided you know exactly the underlying colour of the wall itself.

how much is enough? 2%, 10%, 80% water content?

And in what form? Is it hydrated minerals, ie, water chemically bonded into the regolith? Is it water (as water) soaked into the pores of the regolith grains or is it coating the grains?¹ Even if it's downright "wet", is the water in regolith (frozen mud) or in rock (frozen aquifer)? Is it collected into pockets of ice, or evenly distributed throughout the regolith/rock? The latter forcing you to process much more material. Or if you drill down, is there a wet aquifer?

The answer radically changes the difficulty of extracting water, the energy costs, and the equipment/man-power required.

¹ Soil has three types of water: Excess, which drains when allowed. Structural, where the water fills the gaps between the grains, but doesn't run through. And absorbed, where the water fills the pores of the grains themselves. (Those aren't the proper names.) Even with the same percentage of water, how it's available will vary wildly depending on the type and texture of the grains. On a farm, you want a lot of structural capacity, pore-held water isn't available to the plants, and excess water just runs through. On Mars you would want grains with poor holding capacity, with most of the water as frozen excess. That way you can just heat the regolith above freezing and it will drain through your filter. The worst case (other than rock) would be grains with high absorption, where you have to boil the water out. That obviously increases your energy costs greatly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/10/2017 09:41 pm
I'd rather be where the water is.

Plenty of water is even near the equator.

It actually bothers me. Huge amounts of water are necessary for plans that involve fueling rockets on mars. But it's utterly unclear to me where it comes from. Has this been convincingly addressed somewhere? Is it pulled form the dry air or squeezed from the dry sand or is it supposed to be found in a cave?

I looked into this, the water at the equator was inferred from reanalysis of neutron data from Odyssey, but I'm sceptical of this as there is no explanation that I can find with a cursory look as to why it's not sublimed. Technically is hydrogen abundance that is measured, so more info required to confirm if it is water. There is also evidence of buried 'pack ice' at Elysium Planitia (http://www.esa.int/Our_Activities/Space_Science/Mars_Express/ESA_s_Mars_Express_sees_signs_of_a_frozen_sea), but this would have to be under a reasonable about of dirt.

 
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 11/10/2017 09:49 pm
NSF discussions are normally technical in nature. In that vein, consider the mass of a pressure vessel, or Dome if one is to insist that domes are pressure vessels.

https://en.wikipedia.org/wiki/Pressure_vessel#Scaling (https://en.wikipedia.org/wiki/Pressure_vessel#Scaling)

Quote
Spherical vessel

For a sphere, the minimum mass of a pressure vessel is

    M = 3 2 P V ρ σ {\displaystyle M={3 \over 2}PV{\rho \over \sigma }} M={3 \over 2}PV{\rho \over \sigma },

where:

    M {\displaystyle M} M is mass, (kg)
    P {\displaystyle P} P is the pressure difference from ambient (the gauge pressure), (Pa)
    V {\displaystyle V} V is volume,
    ρ {\displaystyle \rho } \rho is the density of the pressure vessel material, (kg/m^3)
    σ {\displaystyle \sigma } \sigma is the maximum working stress that material can tolerate. (Pa)[12]

Other shapes besides a sphere have constants larger than 3/2 (infinite cylinders take 2), although some tanks, such as non-spherical wound composite tanks can approach this.

With this, the surface area can be calculated for your preferred volume using S/V = 3/R or S = 3 V / R. Now thickness can be calculated as t = M/rho S. Continuing in this vein I get a formula for thickness, t =P*R/2 *sigma. Make sure that you derive this formula for yourself before you use it, I am notorious for making "minor" errors in derivations.

Many kinds of polyethylene are known, with most having the chemical formula (C2H4)n. Seems like the raw material is available on Mars. But the working stress is low. Even so, my formula applied to a sphere with a 500-meter radius made of HDPE, containing one psi pressure would only need to be 6 tenths of an inch thick if pressurized to yield stress.

Digging out the 500-meter deep pit to bury half the sphere may be a challenge, I suggest a room and tunnel system where the tunnels are 3-meter diameter cylinders laid out on the surface, and the rooms are 5 to 15-meter diameter spheres. Fifteen-meter spheres make for very big rooms but are admittedly not city-sized.

Digging a 2-1/2 meter deep pit to bury a 5-meter sphere is not nearly so tricky as trying to anchor a 5-meter dome then sealing the soil to be airtight. Remember, whether the dome is a habitat or a greenhouse, the oxygen content is quite valuable and you don't want it leaking away.
The idea is to use a thin layer (or double layer most likely) and then reinforce with a net or grid of cables. That's what large pressure stabilized domes look like. You can use very strong material for the cables; the thin material doesn't need to be particularly strong; other qualities like transparency are equally important.

For the cables, you would use something strong and lightweight. Strength is probably more important than weight if you're building them on Mars.

For stuff brought from Earth, you'd use Zylon or carbon fiber or similar. For ISRU, instead of the HDPE form of polyethylene, you would want UHMWPE, which has a very high strength to weight ratio. You could also use basalt fiber (basalt is common on Mars, and it's stronger than fiberglass) or steel/iron.

Maybe, but what does the math say? I showed mine, let's see yours!
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/10/2017 09:59 pm
I looked into this, the water at the equator was inferred from reanalysis of neutron data from Odyssey, but I'm sceptical of this as there is no explanation that I can find with a cursory look as to why it's not sublimed.

You mean the Wilkinson Wilson et al. paper I assume. I am also skeptical because they used some fancy algorithm to increase the resolution of raw data. Such schemes I suspect are based on interpolation and sharpening algorithms. While working well to bring out detail in some data, I fear they are prone to create artifacts. Scientist are often susceptible to overinterpreting such artifacts.

edit: Wrong name
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/10/2017 10:12 pm
Yeah, this is the link to the paper, I've not read it properly yet.

Equatorial locations of water on Mars: Improved resolution maps based on Mars Odyssey Neutron Spectrometer data (http://www.sciencedirect.com/science/article/pii/S0019103516306029#fig0003)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/10/2017 11:12 pm
what would a proper pressure vessel be like?
Here is one option:
[...]
Or alternatively:
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1454793;image) (http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1454793;image)

The framework in Lamontagne's render is a good demonstration of the lines-of-force issue with domes. If you think of his ellipsoid as two domes cupped, the strength required to hold the force that the top half exerts on its rim is shown in the structure of the bottom. (And vice versa.) By definition, the bottom structure must be as strong at the top.

If you have a dome on the ground¹, the scale required for your anchoring is shown by the bottom half of the ellipsoid.² What you remove is what you have to replace.³

As KelvinZero noted, the optimum shape is a sphere. Whatever the actual shape of your pressure vessel, that's what it's trying to become; hence that's the "shape" of the forces on the structure, strongest wherever the walls deviate the most from that. In Lamontagne's ellipsoid hab, the structure will be trying to pull the rim inwards to circularise the lines-of-force, and hence it would need extra strength around the rim to cope with that.³ So if you go further and make the bottom half a flat floor (as in a sealed-floor dome), you can see how you are creating a worst-case edge effect long the rim. Essentially it's a zero radius, ~100° bend. All of the bending force across the entire thing ends up focused on that line, creating an entire extra layer of structural problems for no benefit over a proper pressure-vessel, other than satisfying your SF image of a "dome on Mars". Is an ellipsoid on Mars not futury enough for you? Why use the wrong structure for the job?

[Obviously having an open-floor is another issue on top of that. But for the sake of this I'm assuming the dome is at least a properly air-tight structure.]



¹ (Or worse, on the rim of a crater or valley.)

² (With independent anchors, the lines of restraint don't curve around and join, the anchors are using sheering force in the ground to balance the tensile force on the anchor rather than hoop-strength. That shows how difficult it would be to anchor a larger structure, because the individual anchors would be "using up" the rock/regolith mass of their neighbours, forcing you to drill much deeper. You can avoid some of that by reinforcing the rim of the dome horizontally (an extra ring-structure around the rim), with compression members capable of withstanding the entire horizontal force, leaving you with only the vertical vector; but however you divide out the vectors, you clearly aren't saving material or effort over Lamontagne's ellipsoids.)

³ (This is a problem with any pressure vessel: when you create an opening, you are, in effect, cutting through the great-circles of the lines-of-force that provide the tensile hoop-strength in the skin or frame. That weakens the area around the opening, the cut lines-of-force are pulling on the edges; you're going from even tensile forces to buckling or tearing force. (This is why I like the geodesic image, you can picture lines of force as discrete entities rather than continuous.) The larger the opening, the greater percentage of lines-of-force you are cutting, and hence the greater the amount of force focused on the edges of the cut. A dome under internal pressure is pretty much a worse-case scenario. You can picture this, again, using Lamontagne's image. If you remove a small section of the frame, you need to reinforce the surrounding elements to replace that lost strength. And indeed, the frame itself is a series of openings, each frame-segment has to withstand the bowing force of the skin connected to it, as well as the tensile force of the overall structure. The coarser the frame (bigger the openings) the more the angle of force on the frame is non-tensile and the heavier the frame has to be. The optimal geodesic exploits the balance between the gauge-strength of the framing material at the target tension (or compression), and the inherent bending limits at that thickness.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/10/2017 11:31 pm
I forgot to ask when you first posted this...

My vision of the fancy Mars biodome is more or less on that stock photo above. Positive pressure, but barely over ambient, leaky. It would surround the pressurized colony (could be tin cans or other pressure vessels) which dumps its waste heat and gasses into it.

By "biodome", do you mean something with plants? If so, you can't grow plants in a pure CO₂ atmosphere, at any pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/11/2017 01:34 am
what would a proper pressure vessel be like?
Here is one option:
[...]
Or alternatively:
(http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1454793;image) (http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1454793;image)

The framework in Lamontagne's render is a good demonstration of the lines-of-force issue with domes. If you think of his ellipsoid as two domes cupped, the strength required to hold the force that the top half exerts on its rim is shown in the structure of the bottom. (And vice versa.) By definition, the bottom structure must be as strong at the top.

If you have a dome on the ground¹, the scale required for your anchoring is shown by the bottom half of the ellipsoid.² What you remove is what you have to replace.³

As KelvinZero noted, the optimum shape is a sphere. Whatever the actual shape of your pressure vessel, that's what it's trying to become; hence that's the "shape" of the forces on the structure, strongest wherever the walls deviate the most from that. In Lamontagne's ellipsoid hab, the structure will be trying to pull the rim inwards to circularise the lines-of-force, and hence it would need extra strength around the rim to cope with that.³ So if you go further and make the bottom half a flat floor (as in a sealed-floor dome), you can see how you are creating a worst-case edge effect long the rim. Essentially it's a zero radius, ~100° bend. All of the bending force across the entire thing ends up focused on that line, creating an entire extra layer of structural problems for no benefit over a proper pressure-vessel, other than satisfying your SF image of a "dome on Mars". Is an ellipsoid on Mars not futury enough for you? Why use the wrong structure for the job?

[Obviously having an open-floor is another issue on top of that. But for the sake of this I'm assuming the dome is at least a properly air-tight structure.]



¹ (Or worse, on the rim of a crater or valley.)

² (With independent anchors, the lines of restraint don't curve around and join, the anchors are using sheering force in the ground to balance the tensile force on the anchor rather than hoop-strength. That shows how difficult it would be to anchor a larger structure, because the individual anchors would be "using up" the rock/regolith mass of their neighbours, forcing you to drill much deeper. You can avoid some of that by reinforcing the rim of the dome horizontally (an extra ring-structure around the rim), with compression members capable of withstanding the entire horizontal force, leaving you with only the vertical vector; but however you divide out the vectors, you clearly aren't saving material or effort over Lamontagne's ellipsoids.)

³ (This is a problem with any pressure vessel: when you create an opening, you are, in effect, cutting through the great-circles of the lines-of-force that provide the tensile hoop-strength in the skin or frame. That weakens the area around the opening, the cut lines-of-force are pulling on the edges; you're going from even tensile forces to buckling or tearing force. (This is why I like the geodesic image, you can picture lines of force as discrete entities rather than continuous.) The larger the opening, the greater percentage of lines-of-force you are cutting, and hence the greater the amount of force focused on the edges of the cut. A dome under internal pressure is pretty much a worse-case scenario. You can picture this, again, using Lamontagne's image. If you remove a small section of the frame, you need to reinforce the surrounding elements to replace that lost strength. And indeed, the frame itself is a series of openings, each frame-segment has to withstand the bowing force of the skin connected to it, as well as the tensile force of the overall structure. The coarser the frame (bigger the openings) the more the angle of force on the frame is non-tensile and the heavier the frame has to be. The optimal geodesic exploits the balance between the gauge-strength of the framing material at the target tension (or compression), and the inherent bending limits at that thickness.)

With internal tension elements (cables) you can make a pressure vessel whatever shape you want (including a dome) with a mass/volume ratio reasonably close to to the ideal of a sphere.

Domes are practical because they enclose a lot of floor area at grade without requiring excavation or building up to the main floor, and cool because they allow a lot of "open" space, even with internal cables.
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/11/2017 07:51 am
By "biodome", do you mean something with plants? If so, you can't grow plants in a pure CO₂ atmosphere, at any pressure.

I was thinking cyanobacteria, not because of lack of oxygen but because of temperature. The growth environment would be pretty close to the Don Juan pond. I wouldn't worry too much about the oxygen requirement of plants anyway, they can make their own.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/11/2017 09:09 pm
I wouldn't worry too much about the oxygen requirement of plants anyway, they can make their own.

Plants¹ can't tolerate a high (or pure) CO₂ atmosphere. It causes acidification inside the leaves and burns the plant tissue.

They also can't tolerate no oxygen, requiring reabsorption of oxygen through their roots and when they aren't photosynthesising. They also can't tolerate low atmospheric pressure, amongst other things it triggers their drought reflex because they can't absorb enough water, no matter how much is available. Plants are really twitchy sensitive. It's quite bizarre. (It would be an interesting project to see how many of these issues could be selectively-bred out or genetically-engineered around, given the wide variety of environments that plants do survive in.)

Obviously, cyanobacteria isn't a plant, and apparently does tolerate high CO₂. (And fairly low pressure. I've seen research claiming good growth down to 5kPa (5% of SLe, but 8 times Mars average.) Below that, water isn't liquid.) Algae also handles pure CO₂, but I can't find any reference for pressure tolerance. I suspect that as long as water is liquid (ie, >5kPa) then it should be fine.

¹ (Normal vascular plants like crops, etc.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/11/2017 10:09 pm
good growth down to 5kPa (5% of SLe, but 8 times Mars average.) Below that, water isn't liquid.

But brine can be. Saturated CaCl2 at melting point (-51C) should have vapor pressure <5 Pa. It should be liquid in pretty near vacuum.

edit: And why do you say that water can't be liquid below 5kPa? Triple point of water is at 611 Pa.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/12/2017 03:55 am
Here is my dome math.

I think it would be practically impossible to anchor a true dome on Mars, without a very thick floor.


I've also included a spreadsheet on thermal equilibrium, in case that comes up again  :-)

A large enough dome, however, would eventually self anchor, once it was massive enough to balance atmospheric pressure.  About 20km across, if made of steel.  Basically, once the dome weight reaches 10 tonnes per m2 (On Mars, i.e 30 tonnes per m2 on Earth) it could go on indefinitely. Mustn't lose air pressure though!



Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 11/12/2017 04:37 am
Here is my dome math.

I think it would be practically impossible to anchor a true dome on Mars, without a very thick floor.


I've also included a spreadsheet on thermal equilibrium, in case that comes up again  :-)

A large enough dome, however, would eventually self anchor, once it was massive enough to balance atmospheric pressure.  About 20km across, if made of steel.  Basically, once the dome weight reaches 10 tonnes per m2 (On Mars, i.e 30 tonnes per m2 on Earth) it could go on indefinitely. Mustn't lose air pressure though!

Thanks for running those calc's.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/12/2017 05:10 am
Basically, once the dome weight reaches 10 tonnes per m2 (On Mars, i.e 30 tonnes per m2 on Earth) it could go on indefinitely. Mustn't lose air pressure though!
I think it could be even slightly better, because for very high domes, the top of the dome would have lower air pressure to contain.

Im not sure of my logic here: is it that the mass per m3, of dome material plus enclosed atmosphere, has to be 30 tons in mass? (in order to exert the pressure that 10 tons of atmosphere would exert on earth)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/12/2017 05:30 am
Basically, once the dome weight reaches 10 tonnes per m2 (On Mars, i.e 30 tonnes per m2 on Earth) it could go on indefinitely.
Im not sure of my logic here: is it that the mass per m3, of dome material plus enclosed atmosphere, has to be 30 tons in mass? (in order to exert the pressure that 10 tons of atmosphere would exert on earth)

Pressure is exerted outward on the shell, so the constraining mass must be on (or by) the shell, exerted inwards.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/12/2017 10:18 am
Here is my dome math.

I think it would be practically impossible to anchor a true dome on Mars, without a very thick floor.


I've also included a spreadsheet on thermal equilibrium, in case that comes up again  :-)

A large enough dome, however, would eventually self anchor, once it was massive enough to balance atmospheric pressure.  About 20km across, if made of steel.  Basically, once the dome weight reaches 10 tonnes per m2 (On Mars, i.e 30 tonnes per m2 on Earth) it could go on indefinitely. Mustn't lose air pressure though!
Or you can fill the cells of the dome with water...

As far as anchoring, you just have to go deep. Not impossible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/12/2017 11:32 am
Or you can fill the cells of the dome with water...

As far as anchoring, you just have to go deep. Not impossible.

Ok, Paul wins that one I guess. At kilometer scales and breathable pressures domes seem impractical. I doubt building such structures is a problem that needs a solution in my lifetime though. A small, low pressure greenhouse wouldn't need a full pressure vessel. I wonder where the limits are where one design trades better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/12/2017 11:43 am
I don't see why domes are any LESS practical than any other solution. Paul just has more time to argue on this thread than I do.

Put down deep anchors (which isn't hard), and you're fine.

If you want a very large space, there's really nothing that can compete with domes. Which are pressure vessels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 11/12/2017 12:03 pm
I don't see why domes are any LESS practical than any other solution.

Yeah, building a kilometer diameter ball and digging it halfway into the ground is no more practical. The whole concept of a giant bubble is impractical.

If you want a very large space, there's really nothing that can compete with domes. Which are pressure vessels.

It has to be many interconnected small ones built gradually. Both spheres and domes could be built and practice will determine the best design for each application.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/12/2017 09:51 pm
A small, low pressure greenhouse wouldn't need a full pressure vessel.

No, the argument is still the same at small scales and at lower pressure. The effort needed to make a small open-floored dome work ends up being more than is required to make a sealed structure work, and the effort required to turn a sealed structure into a sort-of-dome is more than if you just used a mundane pressure-vessel shape (a spheroid, ellipsoid, rounded-end true cylinder or elliptical cylinder.)

The point is that it's always going to be more effort (and material, and cost) to engineer a dome than a proper pressure vessel of the same size. You are deliberately choosing the wrong structure for the job.

Domes are brilliant compression structures. It's why there are so many arches and vaults in pre-steel construction, and why it's still the go-to shape for covering wide open areas. They suck for holding a pressure, which is why you don't see dome-shaped pressure-tanks, at any scale. (Slight exception for large concrete pressure-tanks, which use their sheer mass to "cheat".)



Aside,

Yeah, building a kilometer diameter ball and digging it halfway into the ground is no more practical.

You don't have to bury pressure vessels. A frame that's capable of holding the air-pressure is also capable of supporting the whole shape above ground (or rather, the air-pressure is supporting the shape.) The idea of half burying it just came up because... I think it was KelvinZero... brought it up as a way to get pseudo-domes. (The surface appearance of "a dome on Mars" without the cost.) For example, have your industrial stuff below ground level, have your main crop layer at ground level, with a core of tall buildings (possibly hanging from the frame, given the enormous lift given by atmospheric pressure) to give you a view. Read earlier in the thread.

But you don't necessarily have to excavate to achieve even his idea. Plenty of small (<2km) craters are fairly neat bowl shapes.

(https://www.universetoday.com/wp-content/uploads/2015/01/ESP_011588_2225_RED.browse.jpg) (https://www.universetoday.com/wp-content/uploads/2015/01/ESP_011588_2225_RED.browse.jpg)

(Newish 1km impact.)

[If you found the right site, you could build a small ellipsoidal structure at the centre, then add successive layers of larger structures. Kind of like the expansion of medieval walls around cities.]

Whereas if you tried an open-floored dome over that crater, the structure wants to rip out the walls, exactly where you have the least material to anchor into.



Or you can fill the cells of the dome with water...

Around 30m thickness of water will reduce light levels. AIUI, in clear water you'll lose about 80% in the first 10 metres. (And 100% of red, which is important for plants. Blue is least affected.)  So for all that effort, what have you gained? A dimly lit hole. But at least it's a dome!

(And top weight doesn't help with the lateral vector, so you'll still need reinforcing around the rim.)

As far as anchoring, you just have to go deep. Not impossible.

I've never said it was impossible. I just said it's dumb because you aren't saving anything. You end up with as much or more effort/cost than if you'd just used a natural pressure vessel shape. You are making all this extra effort to use the wrong structure, to fight the internal pressure instead of using it for you, because you started with the idea that "domes are easier" and just will not give it up.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 11/12/2017 11:03 pm
As far as anchoring, you just have to go deep. Not impossible.

Actually, I'm not sure that it is possible. Check the Internet for the math on anchor design - (look at retaining walls). You will find that the anchor is resisted by a conic section of the fill (regolith) which means that the deeper the anchor, the further apart they need to be in order to lift on more of the covering material. That is, two anchors really close together but deep are no better than one marginally bigger anchor. The central angle of the conic section is a function of the regolith characteristics, but what you gain by going deep is the resistance of the mass at the top of the conic section. BUT - the anchors need to be further apart to avoid defeating the purpose of going deep. While you do gain from the extra mass over the anchor in the radial direction of the dome, you don't gain much in the circumferential direction because the anchors need to be more widely spaced and you can't gain by using more anchors at the same depth. One way if saying this is "You can't just go deep, you have to go a lot deeper."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/12/2017 11:49 pm
Of course it's possible. You can just use larger anchors. Just do a little research on anchor design, and it's clear if you go deeper, you get much stronger.

As far as a stiff structure being lighter than cables and a flexible dome, you must be kidding, right? Anything which requires substantial compressive loads will be really heavy (unless, you guessed it, pressure-stabilized). That's because you get Euler buckling for compressive loads, and so your structures tend to get complicated real fast. This is especially difficult for large structures.

Tensile loads carried by cables is the lightest thing possible. If you think some welded together pressure vessel placed on posts will be lighter, you are sadly mistaken.

...as far as 30m of water, no. We were talking 1.7psi, which is just 3m of water and conveniently provides plenty of shielding. One can imagine some compromise, like 3psi, so you split the loading between tensile and the water shielding.

As far as a blue tint, how is that a problem? Poppycock! It'd make it look better. And with just a few meters, it would be a huge effect, either. Compensating for the red tint of Mars would provide a pleasant effect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/13/2017 01:00 am
Regarding anchors, eventually, you could just curve them inwards, connect them together, and then you get an inverted dome... i.e. anchors are really just a different form of the other side of a pressure vessel.  They transform large amounts of rock into a gigantic flat plate that serves as the flat of a pressure vessel  Since the ground is already there it is cheap, but the anchors might get just as expensive as simply building a spherical or elliptic structure and filling half of it with soil.

Getting away from domes, I think this is what a typical tunnel should look like on Mars.

Use locally produced materials to build structures, a pleasant amount of variety, lots of potted plants.

These are views of the old center of Estepona, in Spain.
High density, low maintenance, pleasant to the eye.  You could bounce lamps from a white painted roof and it would look almost exactly like this.
Every street has a different color of pots for the plants, very interesting.
There is no need for a tunnel to be dark and monotonous.

I found Estepona quite amazing.  Any other street you know that would be interesting?  Pictures would be nice!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/13/2017 01:07 am
Right, if you want you could build it that way. The advantage is you wouldn't need film on the underside and probably a lot less interconnecting webbing. And for very large domes, the weight of the soil would mean you could place the anchors a lot shorter into the soil than the ceiling is high.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/13/2017 01:08 am
These are just to show the thickness required for a flat pressure vessel, i.e the floor of a dome, compared to a continuous construction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/13/2017 01:14 am
That's incorrect, as the dome is not made of an isotropic material like metal but cables which are continuous and buried deep. Thus, you would not get the stress concentrations you would if the dome were metal since on the interface between the floor and the cables the cable would be able to move relatively freely.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/13/2017 01:20 am
Right, if you want you could build it that way. The advantage is you wouldn't need film on the underside and probably a lot less interconnecting webbing. And for very large domes, the weight of the soil would mean you could place the anchors a lot shorter into the soil than the ceiling is high.
As the dome gets larger, it gets heavier for the same interior volume and slowly gets less spherical and more elliptical.  Eventually, it becomes a flat sheet, that exactly balances internal pressure and no longer requires anchoring.  My friend Robert Kennedy wrote an interesting paper on Shell Worlds exploring this concept.  Stability and safety might create some problems  :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/13/2017 01:27 am
That's incorrect, as the dome is not made of an isotropic material like metal but cables which are continuous and buried deep. Thus, you would not get the stress concentrations you would if the dome were metal since on the interface between the floor and the cables the cable would be able to move relatively freely.
I'm not quite certain what is incorrect here, but I'm pretty certain were saying about the same thing.  I do like my idea of just exposing the lower part of the dome, and using that as part of the habitat.  Once something is large enough, you can just build a lot of flat areas inside it, no need for a single floor.

That being said, I still think deep caves are much more logical and safe that domes.  Domes would be more useful as parks and architectural statements than as habitats.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/13/2017 01:35 am
I doubt that it'd be spherical to begin with. Large pressure-stabilized roofs generally aren't. This is partially an artifact of using cables (which are only loaded in one direction, versus two when building from isotropic metals) and partially due to being loaded with things hung from it like speakers and lights (in the case of a stadium roof) or water-filled cells (in the case of a Mars dome).

I've been in such very large pressure-stabilized domes many times.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/13/2017 01:37 am
That's incorrect, as the dome is not made of an isotropic material like metal but cables which are continuous and buried deep. Thus, you would not get the stress concentrations you would if the dome were metal since on the interface between the floor and the cables the cable would be able to move relatively freely.
I'm not quite certain what is incorrect here, but I'm pretty certain were saying about the same thing.  I do like my idea of just exposing the lower part of the dome, and using that as part of the habitat.  Once something is large enough, you can just build a lot of flat areas inside it, no need for a single floor.

That being said, I still think deep caves are much more logical and safe that domes.  Domes would be more useful as parks and architectural statements than as habitats.
I suspect that there will be MULTIPLE types of habitats used. Musk has mentioned domes and tunnels (as well as other CGI habitats, though that's not meant to be taken literally).

People underestimate the difficulty involved in digging when adjusting for volume.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 11/13/2017 02:27 am
By using cables tied to deep anchors, and dividing the large dome into several floor levels, what is the effective difference between such a dome and a rectangular, multistory building?

The building has the advantage that the walls can be tied together with cables that have a straight pull. The ceilings (floors) tied to the deep anchors can also have a straight, vertical pull. One could even deliberately use different, higher pressure on the lower floors with different, lower pressure on the higher floors, This would be a means to guarantee air circulation throughout the structure while easing the load on the anchors to the upper floors. The top floor would become the greenhouse/park as well as the air circulation system sump ensuring that recirculated air is freshly oxygenated. Soil mass on the top floor also eases the load on the vertical anchors a little bit. To further ease the load, the "in-between" space between the top floor and the ceiling of the next-to-top floor could be used for water storage tanks. The remainder of the building would be conventional. The ceiling of the top floor or roof of the building may even simulate a dome-shape if you insist.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/13/2017 03:46 am
Tensile structure vs non-tensile. Dome is tensile-dominated and so will be MUCH lighter and use less material.

Or to put it another way: a dome, because it's tensile-dominated, can encompass a much larger volume for the same structural mass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/13/2017 04:25 am
I found Estepona quite amazing.  Any other street you know that would be interesting?  Pictures would be nice!

http://www.carfree.com/
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/13/2017 11:16 pm
Tensile structure vs non-tensile. Dome is tensile-dominated and so will be MUCH lighter and use less material.

Or to put it another way: a dome, because it's tensile-dominated, can encompass a much larger volume for the same structural mass.

I like the idea of separating functions, shell for pressure, independent structure for general construction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/14/2017 01:28 am
Estepona in a tube.  :-)

With added texture and wall elements this would eventually look quite lived in, I expect.

Tunnel created by a large roadheader, 300 m3/hr and more
Bounce lighting from the ceiling, lamps can be rotated for various effects.
Utilidors are above the buildings, in the 2 triangular sections.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/14/2017 08:27 am
I've been in such very large pressure-stabilized domes many times.

There aren't that many, and the majority have been torn down (or tore themselves down) and replaced due to the problems they have. People were taken in by the illusion of low cost construction, but even their creator, David Geiger, was moving away from air-supported structures to self-standing structures (like Florida's Suncoast Dome (Tropicana Field) which he designed before he died).

Interesting article about one of the last permanent pressure-supported dome stadiums in the world (http://thenewshouse.syr.edu/dome35/2015/12/14/the-carrier-domes-iconic-inflatable-roof-necessitates-and-complicates-the-facility/):

"The Dome's staff monitors the facility's 16 five-foot diameter fans around the clock. [...] Managing Director Pete Sala said that maintaining the right amount of air pressure in the building is incredibly demanding. 'It takes a constant effort to keep the Dome aloft,' he said."

(From another article about the (snow caused) Metrodome failure: "Griffis also points out that maintenance costs tend to be higher than many owners want to pay; for example, maintaining air pressure can be both laborious and expensive. Maki, for example, says his facility's monthly electricity bill runs about $60,000. [...] They have 20 'blowers,' or fans, on the stadium's 'mechanical' level, located just above the upper concourse and below the roof; and each blower pumps at 100 horsepower and 2,800 cubic meters per minute. [...] 'There are better technologies out there,' Griffis says. 'We've probably seen the last of air-inflated tensegrity domes.' "

Digging around, it looks like the Carrier Dome runs at around 100 pascals, or 0.015psi (when not supporting snow, which requires nearly 1kpa to support) and requires upwards of 3000 m³/min to maintain that tiny amount of over-pressure; although the 16 fans are capable of more, obviously, when dealing with the extra weight of snow.)



Aside: In spite of my hammering of this issue, I'm not in some way philosophically opposed to domes or air-supported structures. I was always a fan of the idea (no pun intended), going back to Fuller and his idea of city-domes. And for the moon/Mars: Tenting over craters, enclosing whole valleys! 20-30 years ago I particularly pushed the idea of domes (or rather dome-roofed tessellating structures) for paraterraforming as superior to the more conventional proposals for terraforming. It struck me as a better use of resources and more compatible with natural organic development than top-down planetary-scale terraforming. I was disappointed when I did the maths of the loads involved (along with the problem with air loss through regolith) and realised that domes don't make any sense. Even more disappointed when I realised that clearly all those oh-so-clever designs thrown around by advocates and artists, and even engineers who should know better, clearly hadn't done the basic maths either.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/14/2017 08:42 am
Getting away from domes, I think this is what a typical tunnel should look like on Mars. [picture of cute Med terraced housing]

The majority of space of any settlement will be food production, air/water-treatment, and facilities necessary for fuel/volatiles production.

Actual dwellings will be a minor part of the requirements.

Hence if you solve the former, then that defines the boundaries for the latter. Ie, it's pointless designing cute streets until you know what shape the rest of the system (because it is all part of a system) will take.

If the requirements are to dig frozen aquifers out of rock, then that's where you'll live - because the excavated space is "free". If you need to dig through a buried glacier, ditto. If you need to scrape megatons of regolith into heater/evaporator/condensers in order to get water, then your housing will probably end up in the excavation, or taking advantage of the scale of equipment used, or taking advantage of the huge volume of "waste" de-watered regolith. If instead you are shoving some kind of hot immiscible fluid or gas into wells to unfreeze the frozen aquifers without digging them up, then the needs of the agricultural space will dominate construction (and hence what's easiest/cheapest for building dwellings.)

Cities come from their history. Martian cities will too. First fuel, then agriculture, will dictate the material, placement and layout. Whatever "pretty" you add, will be constrained by those first choices.

[Aside: Nice observation about shell-worlds. That they are part of the "continuum" of larger domes hadn't occurred to me before.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/14/2017 11:48 am
It's not a problem that there's a slight blue tint. Only 3m of water is needed (for radiation protection and to take off some of the load), not the 30m you claimed.

Quit using troll tactics.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/14/2017 01:36 pm
The majority of space of any settlement will be food production, air/water-treatment, and facilities necessary for fuel/volatiles production.

I think you could design the environment so that there was a lot of food production intermingled with dwellings, especially the type of food that goes straight from the plant to the plate with minimal processing. In lamontagnes Estepona in a tube the roof could be covered in tubs full of hydroponically grown vegetables and herbs, see Gardening With Cody for the small scale system that could be used to supplement larger dedicate facilities located elsewhere.

https://www.youtube.com/watch?v=P3gtNKRRVjA
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 11/15/2017 01:25 am
Maybe this debate hinges on the air pressure to be retained under the dome. Some assume standard sea level pressure will be required while others perhaps assume that a much lower pressure will be enough.

Comments?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/15/2017 03:59 am
Anchors must be spaced such that the weight of the cone of regolith above them is at least equal to the load they're supporting times a certain safety factor.

Martian soil has a density of about 1.5kg/liter. And a cone 1meter in diameter and 1 meter deep has a volume of about 260liters, and the volume (of course) increases with the depth cubed (while the atmospheric load only increases with the square).

If we assume a single anchor every 100m by 100m and a 1.75psi (12kPa) internal pressure, then each anchor needs to be 44 meters deep, 70 meters if we use a factor of 4 safety (or a higher pressure or a combination). Probably should have an appropriate anchor design such that slippage is not a concern.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 11/15/2017 05:48 am
Quote
with 1 inAq being a standard pressurization level for normal operating conditions. In terms of the more common pounds per square inch, 1 inAq equates to a mere 0.037 psi (2.54 mBar, 254 Pa)
See https://en.wikipedia.org/wiki/Air-supported_structure (https://en.wikipedia.org/wiki/Air-supported_structure)
Anyone who cares can apply Bernoulli's equation to compute the fan/blower air flow required at this pressure and https://www.engineeringtoolbox.com/fans-efficiency-power-consumption-d_197.html (https://www.engineeringtoolbox.com/fans-efficiency-power-consumption-d_197.html) to compute power required to support a dome pressurized to 1.75 or 3.5 psi, which is 47.3 or 94.6 times greater than Earth standard for air-supported structures.
Of course, you can always line your dome with steel to curtail much of the air leakage. But you wouldn't do this because then your dome becomes a badly shaped cable reinforced pressure vessel.

On digging halfway into the ground. Not necessary although a cradle of some size might be needed to eliminate any risk of corrosion and consequent rupture. An air-filled pressure vessel will support itself while sitting on the ground, just like an air-filled party balloon maintains its shape while sitting on the floor.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/15/2017 01:29 pm
The majority of space of any settlement will be food production, air/water-treatment, and facilities necessary for fuel/volatiles production.

I think you could design the environment so that there was a lot of food production intermingled with dwellings, especially the type of food that goes straight from the plant to the plate with minimal processing. In lamontagnes Estepona in a tube the roof could be covered in tubs full of hydroponically grown vegetables and herbs, see Gardening With Cody for the small scale system that could be used to supplement larger dedicate facilities located elsewhere.

https://www.youtube.com/watch?v=P3gtNKRRVjA
I’ll be adding roof top gardens to the model but that can only provide a few % of the needs. About 10 to 40 times the living area required for food production.  Still a pretty speculative venture, vertical farms.  Even though on Mars they might be horizontal!

BTW if anyone has suggestions for Estepona2 just let me know.  I’m designing it following the carfree web site info.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/15/2017 04:10 pm
Maybe this debate hinges on the air pressure to be retained under the dome. Some assume standard sea level pressure will be required while others perhaps assume that a much lower pressure will be enough.

Comments?

Good point, aero.

Air pressure and leakage are important. A pressure vessel dome avoids leaking by having a floor, but is more massive than an anchored dome (probably more expensive). Leakage through the edges and ground of an anchored dome would require some sort of sealant (adds mass and cost) or continuous replacement of the interior atmosphere (energy inefficient). Both designs have tradeoffs depending on size and application.

I find this argument between types of domes tiresome, especially after several pages. It will be up to architects and civil engineers to design these structures, not internet experts. If you are not an architect or civil engineer with pressurized structure experience, just stop.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/15/2017 07:58 pm
I’ll be adding roof top gardens to the model but that can only provide a few % of the needs. About 10 to 40 times the living area required for food production.  Still a pretty speculative venture, vertical farms.  Even though on Mars they might be horizontal!

BTW if anyone has suggestions for Estepona2 just let me know.  I’m designing it following the carfree web site info.

Check out the Coelux skylights which do a great job of mimicking natural sunlight:

https://youtu.be/EM8psaLBsr8

I posted a link to them back around page 20 in this thread!

Love your renderings of tunnels and the "Estepona" look. Certainly the way to go for Mars habitats, which absolutely need to be psychologically pleasing.

Many Tuscan villages would be good candidates too, for the pleasant and organic "look" that would be good in the tunnels, for instance Montefioralle:
https://www.google.com/search?q=montefioralle+gallery&num=30&safe=off&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwih2-3xu8HXAhVHI-wKHa5CB9sQsAQIJA&biw=1920&bih=963

The natural stones are a shoe-in for Mars...   
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/15/2017 08:06 pm
Do you think it would be worth asking for the dome debate to be split off? It would be a big job for some administrator.

I enjoy back of the napkin maths. I definitely don't care in the context of this thread though. The title says it all:

Envisioning Amazing Martian Habitats

.. it shouldn't get bogged down in page after page of defending/attacking one concept. It should almost be a one post per idea thread. What I would like to see here is extravagant and often visual ideas that would make an awesome coffee table book.

(edit) Or what if we named this to the discussion thread, and started an Update Only thread? That is the one that should just contain all the GCI, youtube clips, relevant news and so on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/15/2017 08:44 pm
BTW if anyone has suggestions for Estepona2 just let me know.  I’m designing it following the carfree web site info.
Many Tuscan villages would be good candidates too, for the pleasant and organic "look" that would be good in the tunnels, for instance Montefioralle. The natural stones are a shoe-in for Mars...   

I agree, old walled towns give a good idea of how area-constrained high-density towns have developed in the past. I really like the ideas in the carfree site, another idea of high density living is the Barcelona Superblocks. And if I have to live in a tube for the rest of my life, I'd really like to have a garden.

https://www.youtube.com/watch?v=ZORzsubQA_M

Edit: Another source that could be of interest is the farm in a tube that is currently supplying London with herbs and greens. You'll need to scroll down a bit in the link to get the story. Growing Underground (http://growing-underground.com/)

Edit 2: Sundrop Farms (http://www.sundropfarms.com/) Hydroponic farm using solar and saltwater producing 15,000 tonnes of tomatoes a year in 20 hectares, or about half the size of a district from the carfree site.

Just spamming thread with links for inspiration, for now at least ;) Hopefully they are helpful.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 11/15/2017 08:47 pm
Deleted posts that were significantly squabble. Some babies got thrown out with the bathwater.

Two people in this thread have PMs they need to read and reply to.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/16/2017 02:22 am
Hi, technical question: would it be reasonable for a wall able to hold 1atm to be able to bulge in either direction? It seems that these walls could be pretty thin.

We discussed cellular concepts before but I was not confident we could build a thin wall capable of holding pressure from either direction. I guess that is what I am really asking, how to efficiently hold pressure from either direction. Bulging walls attached to struts is just a possible way to implement that.

You could probably slash one of these walls even by accident, but with a cellular design most people would live one cell deep, even when looking out over a window. The outer cell would be reserved for uses of space that require less thoroughfare. Also it could have thicker slash-safe walls that could be reused and replaced with thinner ones if the outer layer is expanded.

With bulging walls, couldn't even a cube be a fairly good shape for holding pressure?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/16/2017 10:14 am
I'd like to borrow an idea from Kim Stanley Robinson's Mars trilogy.  The Acheron Fin.

Find a mesa, tunnel in at ground level from 4 sides, meet in the middle and then head upwards excavating different levels as you go.  A greenhouse garden on the roof.  Martian hi-rise.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/16/2017 10:35 am
Wouldn't a mesa be eroding away quite significantly from its sides? Maybe it could be stabilised some way, though. Certainly an attractive concept, though probably not for the first many years on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/16/2017 01:49 pm
Wouldn't a mesa be eroding away quite significantly from its sides? Maybe it could be stabilised some way, though. Certainly an attractive concept, though probably not for the first many years on Mars.

Yes, maybe only a billion years and it is gone.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/16/2017 02:15 pm
Hehe, good point... :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/16/2017 02:21 pm
Hi, technical question: would it be reasonable for a wall able to hold 1atm to be able to bulge in either direction? It seems that these walls could be pretty thin.

We discussed cellular concepts before but I was not confident we could build a thin wall capable of holding pressure from either direction. I guess that is what I am really asking, how to efficiently hold pressure from either direction. Bulging walls attached to struts is just a possible way to implement that.

You could probably slash one of these walls even by accident, but with a cellular design most people would live one cell deep, even when looking out over a window. The outer cell would be reserved for uses of space that require less thoroughfare. Also it could have thicker slash-safe walls that could be reused and replaced with thinner ones if the outer layer is expanded.

With bulging walls, couldn't even a cube be a fairly good shape for holding pressure?
A bulging wall is essentially a Bigelow module.  So yes it is quite possible, and for safety just have many layers of cloth.  Just remember you need continuity in a pressure vessel structure, so the floor would also be cloth, and the ceiling as well, and these would be under tension.  Although this is possible, it is probably expensive compared to other construction methods, since you will essentially be building a number of very strong walls that will probably never be used for pressure sustaining purposes.  Circulating from cell to cell might also be a problem.  The required strength goes up quickly with the size of the interior volume.  And for a long time all materials will come from Earth.
A tunnel on Mars would probably be built something along those lines, as rock is not airtight (lots of cracks and porosities!) Imagine a tunnel as an empty space lined with a thin layer of airtight material, then a protection layer for the airtight material from interior circulation, all supported by a lot of rock outside. This allows the airtight layer to be practically any size, as it is not structural. Then some relatively cheap local construction materials are used for building inside, most likely the material extracted from the tunnel in the first place.  Only the liner is likely to be an expensive material that come from Earth, the rest would be local.
Breaking rocks into large chunks and moving it away with trucks takes a lot less energy than many other construction methods.  I expect the most difficult problem will be the liner and its protection over decades, and eventually centuries.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/16/2017 02:27 pm
I'd like to borrow an idea from Kim Stanley Robinson's Mars trilogy.  The Acheron Fin.

Find a mesa, tunnel in at ground level from 4 sides, meet in the middle and then head upwards excavating different levels as you go.  A greenhouse garden on the roof.  Martian hi-rise.
The roof garden is insufficient.  You need a whole number of garden layers, I expect about 10-40 layers of gardens for each layer of habitation.  The garden layers can be fairly thin, but they will need a lot of artificial lighting.  So add a few km2 of solar panels around the Mesa, or a nuclear reactor not too far away ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/16/2017 03:05 pm
A bulging wall is essentially a Bigelow module.  So yes it is quite possible, and for safety just have many layers of cloth.  Just remember you need continuity in a pressure vessel structure, so the floor would also be cloth, and the ceiling as well, and these would be under tension.  Although this is possible, it is probably expensive compared to other construction methods, since you will essentially be building a number of very strong walls that will probably never be used for pressure sustaining purposes.  Circulating from cell to cell might also be a problem.  The required strength goes up quickly with the size of the interior volume.
I suspect a bigelow wall could not bulge in both directions. In this case I am thinking of a clear plastic sheet, and a fair bit thinner because it is not meant to be robust enough to stand on or slash etc. Robustness comes from redundancy and people generally living on inner layers, leaving outer ones for tasks that need volume but less thoroughfare. Robotic farming perhaps.

A cellular structure isn't more expensive, or at least, only by a constant factor. The mass of a pressure container tends to be proportional to the volume rather than the area. In this case the strength of a pressure container is just distributed though the volume.

If you expand a dome/sphere container, the walls become thicker (keeping the mass:volume ratio constant). However, if you expand a cellular volume by adding new cells, obviously each cell window does not need to be thicker.. but the mass:volume ratio nevertheless remains constant, just like a dome/sphere.

It might seem like the internal walls are not contributing to holding pressure since they have the same pressure on both sides but (a) most of the strength would be in the struts, and these internal struts would still contribute to keeping the entire structure together and (b) If there are internal walls with the same pressure on both sides, these can still contribute to the strength of the entire structure the same way the struts do.

Note: If a single cube can hold pressure, obviously 1000 stacked together (10x10x10) can also hold pressure. However this does not mean the 10x10x10 cube could hold pressure if the internal walls were removed, leaving only the thin shell that was sufficient for a single cube. That would violate the mass:volume ratio rule.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/16/2017 04:17 pm
A bulging wall is essentially a Bigelow module.  So yes it is quite possible, and for safety just have many layers of cloth.  Just remember you need continuity in a pressure vessel structure, so the floor would also be cloth, and the ceiling as well, and these would be under tension.  Although this is possible, it is probably expensive compared to other construction methods, since you will essentially be building a number of very strong walls that will probably never be used for pressure sustaining purposes.  Circulating from cell to cell might also be a problem.  The required strength goes up quickly with the size of the interior volume.
I suspect a bigelow wall could not bulge in both directions. In this case I am thinking of a clear plastic sheet, and a fair bit thinner because it is not meant to be robust enough to stand on or slash etc. Robustness comes from redundancy and people generally living on inner layers, leaving outer ones for tasks that need volume but less thoroughfare. Robotic farming perhaps.

A cellular structure isn't more expensive, or at least, only by a constant factor. The mass of a pressure container tends to be proportional to the volume rather than the area. In this case the strength of a pressure container is just distributed though the volume.

If you expand a dome/sphere container, the walls become thicker (keeping the mass:volume ratio constant). However, if you expand a cellular volume by adding new cells, obviously each cell window does not need to be thicker.. but the mass:volume ratio nevertheless remains constant, just like a dome/sphere.

It might seem like the internal walls are not contributing to holding pressure since they have the same pressure on both sides but (a) most of the strength would be in the struts, and these internal struts would still contribute to keeping the entire structure together and (b) If there are internal walls with the same pressure on both sides, these can still contribute to the strength of the entire structure the same way the struts do.

Note: If a single cube can hold pressure, obviously 1000 stacked together (10x10x10) can also hold pressure. However this does not mean the 10x10x10 cube could hold pressure if the internal walls were removed, leaving only the thin shell that was sufficient for a single cube. That would violate the mass:volume ratio rule.

If you follow this logic to it's conclusion, you end up with pure tensile elements connecting each part of the shell to the part on the opposite side. Those tensile elements can be beams, floors, columns, cables, etc.

The advantages of this constructions method are: 1) you can build any arbitrary shape with the same (or at least similar) structural mass:volume ratio as a thin-wall ideal sphere, and 2) the internal structure, in addition to holding the shell together, can serve as walls/floors/ceilings just like a load-bearing wall in a normal building - except in tension instead of compression.

The main disadvantage is you don't get very large open areas, which would look nice and possibly be psychologically important. The closest you would get is similar to column-and-beam space typical of factories and warehouses.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 11/16/2017 04:30 pm
The main disadvantage is you don't get very large open areas, which would look nice and possibly be psychologically important. The closest you would get is similar to column-and-beam space typical of factories and warehouses.

Indeed.
Areas without large clear sightlines can be depressing and cause real psychological issues.

(https://dncache-mauganscorp.netdna-ssl.com/thumbseg/1470/1470480-bigthumbnail.jpg)

More seriously, tensile ropes, even with truly massive redundancy, perhaps even lit to match the sky take up a very, very small amount of the volume.
These small obstructions can be backlit to reduce visibility, and collapsed down tree-like with trunks that are much less common than the branched supports on the top.

Radiation is of course an issue in pressure supported structures, as there are major issues with safety if you have large masses on top.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/16/2017 04:32 pm
A bulging wall is essentially a Bigelow module.  So yes it is quite possible, and for safety just have many layers of cloth.  Just remember you need continuity in a pressure vessel structure, so the floor would also be cloth, and the ceiling as well, and these would be under tension.  Although this is possible, it is probably expensive compared to other construction methods, since you will essentially be building a number of very strong walls that will probably never be used for pressure sustaining purposes.  Circulating from cell to cell might also be a problem.  The required strength goes up quickly with the size of the interior volume.
I suspect a bigelow wall could not bulge in both directions. In this case I am thinking of a clear plastic sheet, and a fair bit thinner because it is not meant to be robust enough to stand on or slash etc. Robustness comes from redundancy and people generally living on inner layers, leaving outer ones for tasks that need volume but less thoroughfare. Robotic farming perhaps.

A cellular structure isn't more expensive, or at least, only by a constant factor. The mass of a pressure container tends to be proportional to the volume rather than the area. In this case the strength of a pressure container is just distributed though the volume.

If you expand a dome/sphere container, the walls become thicker (keeping the mass:volume ratio constant). However, if you expand a cellular volume by adding new cells, obviously each cell window does not need to be thicker.. but the mass:volume ratio nevertheless remains constant, just like a dome/sphere.

It might seem like the internal walls are not contributing to holding pressure since they have the same pressure on both sides but (a) most of the strength would be in the struts, and these internal struts would still contribute to keeping the entire structure together and (b) If there are internal walls with the same pressure on both sides, these can still contribute to the strength of the entire structure the same way the struts do.

Note: If a single cube can hold pressure, obviously 1000 stacked together (10x10x10) can also hold pressure. However this does not mean the 10x10x10 cube could hold pressure if the internal walls were removed, leaving only the thin shell that was sufficient for a single cube. That would violate the mass:volume ratio rule.

If you follow this logic to it's conclusion, you end up with pure tensile elements connecting each part of the shell to the part on the opposite side. Those tensile elements can be beams, floors, columns, cables, etc.

The advantages of this constructions method are: 1) you can build any arbitrary shape with the same (or at least similar) structural mass:volume ratio as a thin-wall ideal sphere, and 2) the internal structure, in addition to holding the shell together, can serve as walls/floors/ceilings just like a load-bearing wall in a normal building - except in tension instead of compression.

The main disadvantage is you don't get very large open areas, which would look nice and possibly be psychologically important. The closest you would get is similar to column-and-beam space typical of factories and warehouses.
So once built, this eventually ends up as a large building with the flexible plastic windows holding pressure and the floors acting as diaphragms.  You don't need the internal partitions at all, you just need solid floors, working in tension.  Partitions can be set up at reasonable intervals as pressure walls in case of a large leak somewhere.
but don't you end up at square one of Mars design, a building subject to the radiation problem for a wide area near the external walls?  And, basically, aren't tension structures more expensive than compression structures once safety and fabrication cost are factored in?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/16/2017 04:46 pm
General shape of an Estepona2 District, following the Carfree website designs.  More or less.
Density is lower, since I don't expects 4 stories tall tunnels anytime soon.

However we can stack two or three of these, if we really want to :-)
You can get a sense of scale from the tunnel sections to the left, about 9m tall and 24m wide.  Built by a large roadheader, at about 1 to 2m per hour, depending on the rock.

Sealing remains an issue, not necessarily solvable at a reasonable cost.
I will be detailing a fragment, just to get a hint of the overall effect.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 11/16/2017 08:55 pm
What I would like to see here is extravagant and often visual ideas that would make an awesome coffee table book.

Some new ideas and glossy visuals at "Mars Home Planet Urbanization Concept Challenge (https://launchforth.io/hpmars/mars-home-planet-urbanization-concept-challenge/entries/?r=178ed03e-506b-42b5-bae6-c33e61a5ce39)".

(https://ucarecdn.com/c2be3cc6-3ff5-46cf-80c6-5951d4c2cb77/-/preview/496x279/)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/17/2017 12:43 am
A cellular structure isn't more expensive, or at least, only by a constant factor. The mass of a pressure container tends to be proportional to the volume rather than the area. In this case the strength of a pressure container is just distributed though the volume.

Similar to internal cabling. But it will be materially more expensive, because your external shape isn't a clean pressure vessel, you are using the internal struts to pull it into an unnatural shape. Certainly do-able, any shape is do-able (even a you-know-what) if you are willing to throw enough material at it, but you have to allow for that. To make it easier, I'd start with a rhombic-dodecahedral as your base-cell instead of a cube. It should reduce the force on the corners of the structure. It's not a flat-floor shape, but you need a sub-floor space for utilities, so you are always going to have some kind of secondary floor with any structure.

The advantage that may make it worthwhile is that as you complete each cell, it becomes immediately usable. Whereas a larger structure of the same volume needs to be completed entirely before you can use it. For eg, if you can build X volume per year, and you want a 5X volume, it'll take 5 years, during which time you can't use any of the structure, not even for crops. A cellular design might might give you a smaller volume from the same material and effort (say 4 X), but pieces keep coming online every 6 months over that 5 years. That alone - not having to trade size against time - might be worth the less efficient design.



Re: Your original question. I can't think of any theoretical reason why a flexible material capable of holding the required pressure in one direction wouldn't be symmetrically strong. In practice, there might be quirks like the way your framing presses against the flexible material (supporting in one direction, cutting-sharp edge in another), or the layers of material might be progressive in one direction (oxygen/moisture resistance on the inner facing, UV/near-vacuum resistance on the outermost facing. Flip the pressure around and they'll slowly degrade, or even quickly delaminate.) But if you know you are intending to flip the pressurised region, you'd obviously design for symmetry.

However, what happens when it becomes an internal wall? It will just flubber loosely. That might encourage material failure (over time) and so the former-external-now-internal walls might not be much good in an emergency after a few years of sagging neglect.

As an alternatively, would double-layered walls work? (Bubbles inside bubbles.) With a slight over-pressure between the layers, just enough to keep a lens-shape when they are internal walls. When the pressure drops from one side, they'd both bulge in the same direction, but still separated by their frame-width.

Even though Mars has a stupidly thin atmosphere, convection becomes the dominant form of heat loss even when the wind-speed is in the single-digit km/h. Adding a second skin with air trapped between will reduce that loss.

It also helps with your concern about slashing. If you tear the inner layer, the air-pressure would still be held by the outer layer. (And vice-versa.) Belt'n'braces. Buys you time for the maintenance guys to add another temporary emergency cover to hold the pressure while they do the repairs.

[Aside: I was thinking it might work better if the intra-wall pressure was higher than the hab pressure. But I can't picture the flow of force if you had an intra-wall pressure of, say, 1.1atm (where 1atm is any arbitrary hab pressure), 1atm on the habitat-side of the wall, Mars near-vacuum on the outside. Would the force on the outer layer of the wall just be 1.1atm, no different than if the inner layer didn't exist and the hab pressure was higher? Or does the pressure on the inner layer compound somehow? If the former, then the optimum might be to run double-walls at 1.1atm, whether they are external-mains or internal bulkheads. That way the walls don't change direction of the bulge.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/17/2017 12:43 am
However this does not mean the 10x10x10 cube could hold pressure if the internal walls were removed, leaving only the thin shell that was sufficient for a single cube. That would violate the mass:volume ratio rule.

If the skin was removed, but the framing struts remain, then yes, the same 10³ cube would be able to hold the same pressure. Only if the internal part of the frame is removed would the structure not be able to withstand the forces. (Same with any building really, don't cut through beams or columns, don't knock down load-bearing walls.)

In strut'n'membrane structures, the membrane isn't holding the structure together, it's just passing the local force from the air pressure onto the struts. Once you pressurise the internal spaces, the membrane serves no further function (beyond acting as an emergency bulkhead), the direct connections between the internal and external struts are what passes the force through the structure. The walls aren't necessary, only the frame. Likewise, the pressure on the external skin never exceeds the air-pressure difference; regardless of the internal volume. That's why you calculate the overall force on the structure by measuring the external surface area, not the volume.



The main disadvantage is you don't get very large open areas, which would look nice and possibly be psychologically important.

KelvinZero is picturing transparent walls. There should be plenty of light, including of the sky and the Mars surface, and hence a good sense of space.

And presumably as the colony grew and manufacturing capacity increased, it would be more efficient to add larger cells; giving you larger wall-less and strut-less spaces within each cell. [Edit: Especially if your larger cell is a whole integer multiple of the first cells, they'll be compatible with earlier designs. Even rhombic-dodecahedrals can scale in that way.]



You don't need the internal partitions at all, you just need solid floors, working in tension.  Partitions can be set up at reasonable intervals as pressure walls in case of a large leak somewhere.

Under KZ's concept, as cell walls become enclosed by new cells, they function as such emergency bulkheads anyway. And the tensile struts of the internal cells assist the outer cells to withstand the overall force, keeping the force on outer cells the same regardless of the size of the overall structure. Instead of adding internal cabling/framework, and internal partitions, after the fact, they are inherent in the design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/17/2017 04:47 am
I'd like to borrow an idea from Kim Stanley Robinson's Mars trilogy.  The Acheron Fin.

Find a mesa, tunnel in at ground level from 4 sides, meet in the middle and then head upwards excavating different levels as you go.  A greenhouse garden on the roof.  Martian hi-rise.
The roof garden is insufficient.  You need a whole number of garden layers, I expect about 10-40 layers of gardens for each layer of habitation.  The garden layers can be fairly thin, but they will need a lot of artificial lighting.  So add a few km2 of solar panels around the Mesa, or a nuclear reactor not too far away ;-)

Sorry, I was not clear. I did not mean the rooftop garden for food production but as a garden with flowers, plants and greenery to look, touch, smell.  Somewhere to walk and sit after a long day in a tunnel or a vac suit.  Something for the soul more than the body.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 11/17/2017 05:51 am
Mars city living: Designing for the Red Planet (http://news.mit.edu/2017/mars-city-living-designing-for-the-red-planet-1031)

Mars City Design: 2017 Winners Gallery (https://www.marscitydesign.com/2017)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/18/2017 05:17 am
Estepona2 main street.

Plus a few earlier renders I made for this thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/18/2017 06:16 am
Another view of main street.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/18/2017 10:00 am
Thanks jpo234 for posting the picture. Here are three better pictures of Redwood Forest and a short explanation of what (hopefully..) makes it "amazing" :)

In this concept, one giant tree is the central feature of each 50-person domed habitat, and the domes together, connected by a root network, comprise a forest city.

The roots of the tree are the indoors spaces. The above-ground part of the tree is "outdoors", and the Martian surface outside the dome is the real outdoors.

We located most living, working, agriculture and storage spaces in the roots, mainly for the long-term radiation protection and easy organic expandability and connectivity. The leisure facilities, personal gardening and public spaces are in the dome and in the tree branches, so that everyone will have a reason to visit the "outdoors" at least once a day.

A key design goal for Redwood Forest was to provide multiple physical and visual connections between indoors, "outdoors" and outdoors, and between tree-domes. Another was to design in three dimensions, so as to increase the diversity of spaces with different form and function within any given habitat volume.

Our team is continuing to work on Redwood Forest and we would welcome feedback. You can read more about it on  MIT News (http://news.mit.edu/2017/mars-city-living-designing-for-the-red-planet-1031).

(Images copyright: MIT Redwood Forest team)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 11/18/2017 01:54 pm
That's pretty!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/18/2017 09:28 pm
Excellent inspirational visualisations of "Redwood Forest".

I agree that there should be an underground radiation-hardened component of the habitats and some sort of more psychologically pleasing surface room with big windows.

Obviously a base will initially start out with pre-fabs. The landing spacecraft itself plus eventually, if necessary, some hab modules, possible Bigelow-style inflatables.

Afte that, the intrepid colonists would move on to the first habitats produced on Mars, and start with the necessary parts first, which would be the underground part.

With a solid underground habitat established, the "luxury items", i.e. the surface parts can be added. I imagine it will resemble the ISS cupola initially, perhaps even re-using BFR windows.

What if the whole BFS was assembled in a way that would make re-use of its elements easy? - If it was planned for that? The BFS wouldn't carry building elements to Mars, it would BE the building elements. Airlocks, windows, wall elements...
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/18/2017 09:35 pm
What if the whole BFS was assembled in a way that would make re-use of its elements easy? - If it was planned for that? The BFS wouldn't carry building elements to Mars, it would BE the building elements. Airlocks, windows, wall elements...

I suspect that is already the case. The cabins in the BFS look like they fit in through the airlock, in which case you could unload them and use them as a habitat. They could also be used as the basis of a containerized (https://en.wikipedia.org/wiki/Containerization) shipping system, even upto moving people from the ship onto surface transports and habs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/18/2017 11:03 pm
The main disadvantage is you don't get very large open areas, which would look nice and possibly be psychologically important. The closest you would get is similar to column-and-beam space typical of factories and warehouses.
There are a couple of ways of shoehorning that in, rather nicely.

The windows and the frames don't need to change, but if your local industry can produce struts then you can produce them of varying length.

Once you are at a certain scale and want a larger internal volume, you could add internal reenforcing struts in large hoops, either in the shape of a cylinder or a geodesic, and then remove internal cellular elements and reuse them elsewhere.

Once your industry gets to a certain size, there will also be no problem supporting 2x, 3x, 4x cell sizes in different production lines, with larger single panes. Keep it an integer multiple for compatibility.

(more trivially, you would also be able to omit some fraction of internal struts anyway without the whole thing blowing up)
Title: Re: Envisioning Amazing Martian Habitats
Post by: RobLynn on 11/19/2017 12:32 am
Maybe this debate hinges on the air pressure to be retained under the dome. Some assume standard sea level pressure will be required while others perhaps assume that a much lower pressure will be enough.

Comments?

We covered all of this in the other Martian habitats threads.

Lower limit for sustained habitability is about 9psi., roughly 13000 feet.

On earth, there are no towns above that height, but there are some small settlements.

La Rinchonada, Peru, 5130m, (16800ft), population 50,000.  Gold mining city.  51kPa, 7.5psi.  I've spent a few days at this altitude, it's unpleasant and tiring, but for a lot of people it's long-term survivable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/19/2017 12:36 am
Another vision I've had is to find a small impact crater or volcanic outlet, about 30 - 50 metres across. Tunnel in from outside in a number of places and fit airlocks. String a spider web of cables across the crater at a suitable height to support and restrain a clear poly something membrane. Pressurise.

Living and working spaces can be in the crater wall looking into the garden area in the middle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/19/2017 02:17 am
Maybe this debate hinges on the air pressure to be retained under the dome. Some assume standard sea level pressure will be required while others perhaps assume that a much lower pressure will be enough.

Comments?

We covered all of this in the other Martian habitats threads.

Lower limit for sustained habitability is about 9psi., roughly 13000 feet.

On earth, there are no towns above that height, but there are some small settlements.

La Rinchonada, Peru, 5130m, (16800ft), population 50,000.  Gold mining city.  51kPa, 7.5psi.  I've spent a few days at this altitude, it's unpleasant and tiring, but for a lot of people it's long-term survivable.

We've covered this, unless you are genetically adapted fertility is impacted by altitudes over 3,500m or so. Not good for a city with long term ambitions. People in the himalayas have genes from Denisovans that help cope with the low oxygen. Andean populations have evolved a different mechanism. It's an interesting topic.

Tibetans inherited high-altitude gene from ancient human (http://www.sciencemag.org/news/2014/07/tibetans-inherited-high-altitude-gene-ancient-human)
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 11/19/2017 02:24 am
Maybe this debate hinges on the air pressure to be retained under the dome. Some assume standard sea level pressure will be required while others perhaps assume that a much lower pressure will be enough.

Comments?

We covered all of this in the other Martian habitats threads.

Lower limit for sustained habitability is about 9psi., roughly 13000 feet.

On earth, there are no towns above that height, but there are some small settlements.

La Rinchonada, Peru, 5130m, (16800ft), population 50,000.  Gold mining city.  51kPa, 7.5psi.  I've spent a few days at this altitude, it's unpleasant and tiring, but for a lot of people it's long-term survivable.

Some NASA studies suggest 57 kPa (8.3 psi) at 34% O2. With that pressure there's in no prebreathing required for going into a 32 kPa (4.7 psi) pure O2 spacesuit. If I remember correctly, the pros and cons of pressure and O2 level have been discussed in several threads.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/19/2017 02:33 am
I'd like to know how high levels of oxygen effects fires, and any toxic effects before moving in.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/19/2017 04:56 am
Another vision I've had is to find a small impact crater or volcanic outlet, about 30 - 50 metres across. Tunnel in from outside in a number of places and fit airlocks. String a spider web of cables across the crater at a suitable height to support and restrain a clear poly something membrane. Pressurise.

It's doubtful that a crater wall would be able to withstand the force from the air pressure. Assuming 1atm¹, even with such a small diameter, you're still looking at 20,000 tonnes of force pulling upwards (nearly 40 tons per foot around the rim), and depending on the height of the curve another few thousand tonnes pulling the walls inwards. Plus you'll need to seal the floor to avoid air-loss.

So by the time you've reinforced the crater to make it structurally sound, then made it air-tight, it's unlikely that you've saved any effort or material or time compared with using the crater to hold a more natural, self-contained, self-supporting pressure vessel.

(Eg, picture a small version of the Redwood Forest geodesic sphere inside your 50m wide crater (top 2/3rds above the rim), except with the underground "roots" dug horizontally into the walls. The only anchoring would be mundane foundation piers, like any building, which might be integrated into the tunnels.)



¹ (Force is proportional to pressure, so even at half an atmosphere, you're still running 10,000 tonnes upwards pull.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/19/2017 05:42 am
I'd like to know how high levels of oxygen effects fires, and any toxic effects before moving in.

It's been debated endlessly earlier in this thread, and I think the Scaling-Ag thread. A search for "fire OR flammability" should find a few of the times.

Except at very low pressure, changes in percentage oxygen (or rather, percentage buffer gas) plays a greater roll in flammability than partial pressure. That is, the limit of flammability is at a fairly constant %O₂ regardless of pressure, hence minimum psiaO₂ varies strongly with overall pressure. Your lungs work the other way around, requiring a minimum psiaO₂ (around 2psia) regardless of the percentage of buffer gas. (Ditto any liquid chemistry.)

(For example, Zytel-Nylon requires a partial pressure of O₂ of 3.4psia at 14.7psi (with nitrogen as the buffer). At 7psi, it requires just 1.8psia. However, as a percentage, that takes you from 23% O₂ to just 25%. You can barely increase the minimum percentage of O₂ for the same level of flammability, even when you halve the overall pressure. Meaning that if you keep the O₂ partial pressure above 2psia (for humans), a self-extinguishing material becomes easily flammable. And flammable materials become highly flammable, etc.)

You see the same pattern with the minimum temperature required to get a material to ignite, and the speed that the fire moves through the material (and hence the amount of energy released per second, and hence the ability of one material to cause another to ignite.) Things burn faster and hotter at lower pressure even though they have the same psia oxygen.

And annoyingly, the flammability curve of different materials are also different, so you can't trust normal familiarity of materials at Earth-normal. Ie, two materials with similar flammability at Earth-normal might diverge wildly at lower pressure.



Given the danger of fire inside a closed environment, I'd be inclined to increase the overall pressure, while limiting O₂ to around 2.5psia in many areas, in order to reduce flammability (and increase required ignition temperatures, and reduce flame-speed.) It makes everything else harder, you need a stronger structure, you increase EVA pre-breathing times, etc, but... fire bad. And IMO it is just too much to expect to treat a colony like the inside of a space-capsule or EVA-suit; there's just too much required of city-scale living environments to limit your choice of materials to a handful of carefully studied aerospace materials.



[Edit: Oops, sources: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070005041.pdf (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070005041.pdf) for the pressure variation, above. Https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130010991.pdf (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130010991.pdf) for the gravity variation, below.]

[edit2: typos.]



Aside: Counter-intuitively, lower gravity also decreases the minimum oxygen limits for fire. Ie, at lower gravity, material becomes more flammable. It's not a huge effect, 3-5% at Martian gravity depending on the material, but it's yet another thing to watch out for. Even less intuitively, the effect reverses again at very low gravity. (See below.) The worst case seems to be lunar gravity. Poor Loonies can't catch a freakin' break.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 11/19/2017 12:35 pm
La Rinchonada, Peru, 5130m, (16800ft), population 50,000.  Gold mining city.  51kPa, 7.5psi.  I've spent a few days at this altitude, it's unpleasant and tiring, but for a lot of people it's long-term survivable.
A substantial fraction of the population may be genetically predisposed to be able to do well at altitude.
https://www.ncbi.nlm.nih.gov/pubmed/17482897 - is one of many papers on this.

You probably don't want to raise oxygen percentage too much, for obvious fire reasons.
https://en.wikipedia.org/wiki/List_of_highest_large_cities - is interesting.

El Alto is at 4150m, and 1M people.
Between 2500 and 2900m there are cities with many tens of millions total population. Mexico city is at 2200m.

I have not found a nice graph with total population living over a given altitude.
Ideally, you'd want a graph of something like: 'Mortality of people like you plan to send  living at altitude', if contemplating a colony.

Over 2500m, oxygen saturation in the blood tends to fall rapidly, which will affect cognition somewhat.

If you are planning a 'ideal' habitat, you may want to look at agricultural productivity at different pressures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/19/2017 03:13 pm
Maybe this debate hinges on the air pressure to be retained under the dome. Some assume standard sea level pressure will be required while others perhaps assume that a much lower pressure will be enough.

Comments?

We covered all of this in the other Martian habitats threads.

Lower limit for sustained habitability is about 9psi., roughly 13000 feet.

On earth, there are no towns above that height, but there are some small settlements.

La Rinchonada, Peru, 5130m, (16800ft), population 50,000.  Gold mining city.  51kPa, 7.5psi.  I've spent a few days at this altitude, it's unpleasant and tiring, but for a lot of people it's long-term survivable.
And also, at such high altitudes, the partial pressure of oxygen is so low that you can increase the oxygen pressure while keeping the fire risk the same.

3psi is comparable to EVA suit pressure. Perfect for a working environment, allowing you to use Mars atmosphere for pressure and an oxygen mask for breathing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/19/2017 03:17 pm
La Rinchonada, Peru, 5130m, (16800ft), population 50,000.  Gold mining city.  51kPa, 7.5psi.  I've spent a few days at this altitude, it's unpleasant and tiring, but for a lot of people it's long-term survivable.
A substantial fraction of the population may be genetically predisposed to be able to do well at altitude.
https://www.ncbi.nlm.nih.gov/pubmed/17482897 - is one of many papers on this.

You probably don't want to raise oxygen percentage too much, for obvious fire reasons.
https://en.wikipedia.org/wiki/List_of_highest_large_cities - is interesting.

El Alto is at 4150m, and 1M people.
Between 2500 and 2900m there are cities with many tens of millions total population. Mexico city is at 2200m.

I have not found a nice graph with total population living over a given altitude.
Ideally, you'd want a graph of something like: 'Mortality of people like you plan to send  living at altitude', if contemplating a colony.

Over 2500m, oxygen saturation in the blood tends to fall rapidly, which will affect cognition somewhat.

If you are planning a 'ideal' habitat, you may want to look at agricultural productivity at different pressures.
It makes sense to have a very large dome at low pressure and small habs inside at higher pressure. That gives the health benefits of high pressure but weight advantages of low pressure and a defense-in-depth protection against depressurization.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/19/2017 11:16 pm
And also, at such high altitudes, the partial pressure of oxygen is so low that you can increase the oxygen pressure while keeping the fire risk the same.

Not really. As I said above, the reduction in fire risk from reduced pressure is small, the increase in fire risk from increasing the percentage of oxygen is large. The latter dominates the former.

In the example I gave from the NASA paper, even if you halve the overall air pressure, you can only increase the oxygen content by 9% (or two %points) for the same fire risk, reducing the maximum psiaO₂ by over 45%.

[Edit: To put the percentage in context, 9% is the difference between sea-level and 900m -- assuming the same atmospheric pressure at that location because you'll see an easy 5% variation in pressure (and hence oxygen levels) between a high and low pressure system in most area, at the same altitude. OTOH, the psia, 45%, is the difference between sea-level and 5500m. The two effects are hugely different.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/20/2017 01:31 am
And also, at such high altitudes, the partial pressure of oxygen is so low that you can increase the oxygen pressure while keeping the fire risk the same.

Not really. As I said above, the reduction in fire risk from reduced pressure is small, the increase in fire risk from increasing the percentage of oxygen is large. The latter dominates the former.

In the example I gave from the NASA paper, even if you halve the overall air pressure, you can only increase the oxygen content by 9% (or two %points) for the same fire risk, reducing the maximum psiaO₂ by over 45%.
So in other words, yes really.

Anyway, don't want to squabble here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/21/2017 02:37 am
I'm curious about plant resistance to radiation.

In particular would large trees like the one pictured if the habitat have problems from GCRs and solar storms?  I've taken it for granted plants are tougher than animals in many of my designs, but really, perhaps not?  Plants get cancer too, after all, and have complex regulatory mechanisms, it particular the more evolved and energy efficient ones...
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 11/21/2017 03:15 am
Not the same as GCR's, but wildlife around Chernobyl thrives due to lack of humans.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Athrithalix on 11/21/2017 10:17 am
I was under the impression that humans would also thrive around Chernobyl, it's just that they're not allowed to. I don't think the radiation levels are comparable. But I could be wrong.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/21/2017 12:38 pm
I was under the impression that humans would also thrive around Chernobyl, it's just that they're not allowed to. I don't think the radiation levels are comparable. But I could be wrong.

Humans in fact live there. Some old people who were supposed to move out or were moved out just returned to their places. I have seen a biologist checking on the radiation levels in different plants. He said, cherries are carrying a lot of radiation, but it is concentrated in the stone. He eats them, just make sure not to eat the stone. Radiation in Chernobyl is a lot higher than on Mars.

Edit: Different in type of radiation, sure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 11/21/2017 12:39 pm
What dose rate, in mSv/year?
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/21/2017 12:54 pm
I think it's rather variable depending on where you are. Chernobyl Radiation Levels (http://chernobylgallery.com/chernobyl-disaster/radiation-levels/). I have had friends that have gone on tours there and they say the place is amazing, especially the wildlife.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/21/2017 01:26 pm
What dose rate, in mSv/year?

I don't know. For sure some places are worse than others. But it are levels where major radiation damage to animals were expected. That did not happen. There is a herd of wild horses that was sent there as an experiment. Biologists were thinking they send them to certain death or at least lingering illness. Instead a robust healty population developed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/21/2017 04:15 pm
How did we end up in Chernobyl?
On Mars, unprotected solar storms and GCR radiation.  Plants.  Not residual radiation from dust.  The mechanisms are entirely different.


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/22/2017 06:14 pm
A short video of Estepona2.
Hope you enjoy this!

https://youtu.be/jL81lROBae0
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 11/22/2017 06:50 pm
A short video of Estepona2.
Hope you enjoy this!

https://www.youtube.com/watch?v=jL81lROBae0&feature=youtu.be

Very nice! The underground network model for a Mars city will really happen, I think. Apart from the top-notch radiation protection and overall high reliability, building underground probably has the lowest lifecycle cost per cubic meter of habitable space, in the short term and in the very long term.

Creative architects will find hundreds of ways to link the warrens of tunnels with the outside and with direct sunlight. Many have already been proposed in this thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 11/24/2017 03:28 am
A short video of Estepona2.
Hope you enjoy this!

https://www.youtube.com/watch?v=jL81lROBae0

"Underhill" on steroids.  Love your work Michel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/25/2017 08:58 pm
A short video of Estepona2.
Hope you enjoy this!

Really inspirational! - And a European closely-built historical village is obviously a great model for an underground Mars habitat. White-washed walls are also a good idea to combat the natural murkiness you'd expect inside tunnels. You want the LED illumination to bounce off as many surfaces as possible. Lots of plants will be beneficial too. A well-designed underground habitat does not need to be depressing at all.

A while back I thought brick-production and brick-laying wouldn't really be helpful on Mars, since people were just going to live in excavated tunnels anyway. What I didn't think of was that you'll of course need separators in those tunnels and that brick walls are the obvious choice. You can shape them exactly as you wish and they'll conform to any curvature of the tunnels.

Tunnellers and brick-layers wanted for Mars outpost!   
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 11/25/2017 09:12 pm
Check out my "dream" for the aesthetics and functionality of an early-days Martian outpost:

https://youtu.be/ee11pdMrjd0

Village of Dolceacqua ("Fresh water") in Italy.

This is a 360 degree video so you can grab any part of the image with your mouse and pan around.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/26/2017 02:32 am
Re: Dolceacqua, and the like.

I don't think any "early" settlement will look like a place that has been built and rebuilt for centuries. (Dolceacqua castle dates to at least the 12th Century. Presumably the old district has roots going back much, much further, still present in some of the walls and foundations.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/26/2017 03:41 am
A common assumption of Mars habitats is that they will be cramped. Maybe we can do some math on that.

Look at how many tons of hydrocarbons go into a single return flight of a BFS from mars. How many tons of more elaborate hydrocarbons could we make with the same energy budget? How much greenhouse material could we spit out every synod with that much feedstock? How many acres?

I am thinking something along the lines of parallel cylindrical strips running east west with lightweight trough mirrors to bring light levels up to earth levels.

Dont worry about radiation protection and life support costs. That is a wider issue and I have some ideas about that I don't want to divert into right now. Just the basic cost of covering acre after acre in earth-pressure volume. We could also go lower than earth pressure but that is not important. It is only a potential 2x factor that you can throw in or withhold as to your own preference.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/26/2017 04:39 am
An attempt at modular construction elements using Rhombic Dodecahedrons.

As suggested by Paul 451 fro KelvinZero's initial descriptions of flexible multi walled habitats.

Any number of these can be assembled into arbitrary shapes, as long as they can stand up to gravity.

Although the appear complex, they are, I think, in the end, just a series of boxes, and by changing triangular sections (nominally made from a flexible transparent material) into rectangular ones any number of rectangular tubes and sizes of elements could be built.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/26/2017 04:58 am
A common assumption of Mars habitats is that they will be cramped. Maybe we can do some math on that.

Look at how many tons of hydrocarbons go into a single return flight of a BFS from mars. How many tons of more elaborate hydrocarbons could we make with the same energy budget? How much greenhouse material could we spit out every synod with that much feedstock? How many acres?

I am thinking something along the lines of parallel cylindrical strips running east west with lightweight trough mirrors to bring light levels up to earth levels.

Dont worry about radiation protection and life support costs. That is a wider issue and I have some ideas about that I don't want to divert into right now. Just the basic cost of covering acre after acre in earth-pressure volume. We could also go lower than earth pressure but that is not important. It is only a potential 2x factor that you can throw in or withhold as to your own preference.
If you need to stand up to 1 atmosphere, using, for example polyethylene bubbles in a kind of colossal bubble wrap arrangement, and a hoop stress equation as a first approximation  you would need about 30 kg per m2 of 'floor'if the bubbles are 10m in diameter and reinforced with steel wires.  You can check out various diameters and mixes or wires and plastic with the spreadsheet.  i haven't tried to optimize things.
An acre is about 4 000 m2, so each acre requires about 120 000 kg or 120 tonnes.
Safety factors are pretty thin though.
The pure polyethylene dome would be twice as heavy as the steel reinforced one, and require almost 2cm thick walls.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 11/26/2017 07:13 am
What type of polyethylene are you using? I have very little knowledge of polymers but I'm sure that pure polyethylene can be improved on.

Use dacron (Polyethylene terephthalate (https://en.wikipedia.org/wiki/Polyethylene_terephthalate)) as a gas and liquid barrier.
Use dyneema/spectra (Ultra-high-molecular-weight polyethylene (https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene)) to contain the force from the pressure.

These are both engineered polyethylene so would require the same elements to make as rocket fuel (carbon, hydrogen, oxygen), if you can find a source of nitrogen then that opens up the possibility of aramid (kevlar), and maybe epoxy and carbon fibre.

My only knowledge of these materials is from sailcloth (https://en.wikipedia.org/wiki/Sailcloth#Dyneema), so it is very limited.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/26/2017 07:31 am
I suggest a different design for surface habitats. A vertical cylinder, like the big oil tanks.

At the center an appartement block, probably a pressure vessel by itself, at least with lower pressure as a shelter, if the outer shell fails. Strong enough to carry a top cover heavy enough to hold the vertical component of pressure with weight and wide enough to cover a cylindrical transparent side wall. That wall would not have to deal with vertical forces so all pressure force would be horizontal and can be contained by tension elements, no ground anchors required. All transparent segments can be the same size and shape, so easier to manufacture and transport.

With the top cover heavy and not transparent lighting would be limited but still enough to support many decorative plants. Maybe a vegetable garden at the south side.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/27/2017 12:00 am
What type of polyethylene are you using? I have very little knowledge of polymers but I'm sure that pure polyethylene can be improved on.

Use dacron (Polyethylene terephthalate (https://en.wikipedia.org/wiki/Polyethylene_terephthalate)) as a gas and liquid barrier.
Use dyneema/spectra (Ultra-high-molecular-weight polyethylene (https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene)) to contain the force from the pressure.

These are both engineered polyethylene so would require the same elements to make as rocket fuel (carbon, hydrogen, oxygen), if you can find a source of nitrogen then that opens up the possibility of aramid (kevlar), and maybe epoxy and carbon fibre.

My only knowledge of these materials is from sailcloth (https://en.wikipedia.org/wiki/Sailcloth#Dyneema), so it is very limited.
Just regular polyethylene from general tables. It would have to be made with multiple layers, I expect.
As plastic is often fabricated as tubes, a tubular construction would probably be more practical than spheres.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 11/27/2017 12:54 am
Anchors must be spaced such that the weight of the cone of regolith above them is at least equal to the load they're supporting times a certain safety factor.

Martian soil has a density of about 1.5kg/liter. And a cone 1meter in diameter and 1 meter deep has a volume of about 260liters, and the volume (of course) increases with the depth cubed (while the atmospheric load only increases with the square).

If we assume a single anchor every 100m by 100m and a 1.75psi (12kPa) internal pressure, then each anchor needs to be 44 meters deep, 70 meters if we use a factor of 4 safety (or a higher pressure or a combination). Probably should have an appropriate anchor design such that slippage is not a concern.

Bringing this back... an anchored dome might be more viable if it has anchor points in the middle, to cover a large open area but with "pillars" holding the dome down to distribute the pressure differential into more ground.

Perhaps "Mars Gothic" could be a thing?


(https://i.imgur.com/GAhoXPE.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/27/2017 01:40 am
Just regular polyethylene from general tables. It would have to be made with multiple layers, I expect.
As plastic is often fabricated as tubes, a tubular construction would probably be more practical than spheres.
Starting with polyethylene cylinders is fine for a basic value. We can fiddle with different materials and shapes later but it will take pages and only change the answer by a simple factor.

Strength to weight is probably not as important as strength to effort anyway. It is not the same problem as a rocket tank. We are not mass limited. 10x thicker of an easier material may be the way to go. What I was really asking was how much area/volume could we capture with the effort of filling a BFS tank.

We could think of effort in terms of energy budget to start with. An oversimplification but it could make it easier to stick to numbers.

I have no idea how to estimate the energy requirements of polyethylene compared to methane+oxygen. Anyone got any idea?

===

For pressure, how about aiming for 2atm? Living pressure could be somewhat lower than 1atm, giving us something like a 3x safety margin. I also like the idea of the cylinder having 3 layers for good thermal protection and these layers could be designed to slide in opposite directions if punctured, self sealing small holes. Those details are not important for the estimate though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2017 08:34 am
Bringing this back... an anchored dome might be more viable if it has anchor points in the middle, to cover a large open area but with "pillars" holding the dome down to distribute the pressure differential into more ground.

A massive building at the center of the dome. Heavy enough that it can hold down the forces even without anchors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/27/2017 09:34 am
Bringing this back... an anchored dome might be more viable if it has anchor points in the middle, to cover a large open area but with "pillars" holding the dome down to distribute the pressure differential into more ground.
A massive building at the center of the dome. Heavy enough that it can hold down the forces even without anchors.

Do the maths. It would need to be a solid mass, not a building.

For example, for a 100m wide dome at 1atm, to counter the vertical component alone would require a central cylindrical block of solid steel 30m high, 30+m wide. (Or 50 high, 25 wide, if the dome is a hemisphere.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 11/27/2017 09:45 am
Bringing this back... an anchored dome might be more viable if it has anchor points in the middle, to cover a large open area but with "pillars" holding the dome down to distribute the pressure differential into more ground.
A massive building at the center of the dome. Heavy enough that it can hold down the forces even without anchors.
Do the maths. It would need to be a solid mass, not a building.
I think it would get easier as you scale the dome and tower up. The mass you need is proportional to the area (about 30 tons/ square meter) but the mass of the building would be proportional to the volume.

How about a large water reservoir at the top, with apartments beneath?
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2017 10:28 am
Bringing this back... an anchored dome might be more viable if it has anchor points in the middle, to cover a large open area but with "pillars" holding the dome down to distribute the pressure differential into more ground.
A massive building at the center of the dome. Heavy enough that it can hold down the forces even without anchors.

Do the maths. It would need to be a solid mass, not a building.

For example, for a 100m wide dome at 1atm, to counter the vertical component alone would require a central cylindrical block of solid steel 30m high, 30+m wide. (Or 50 high, 25 wide, if the dome is a hemisphere.)

I was replying to the suggestion of adding hold downs to the center of the dome. That would not require to hold down the full vertical component of the force. Part could still be done by anchors at the perimeter.  A 10m concrete and regolith structure would hold the forces for the area of the building. Add the mass of the building below and it can hold more. The 10m roof could expand  beyond the building and the structure may reduce the vertical forces at the perimeter by half.

Edit: the cylindrical structure I suggested before, would need a 10m roof plate to counter the full vertical pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 11/27/2017 01:26 pm
Bringing this back... an anchored dome might be more viable if it has anchor points in the middle, to cover a large open area but with "pillars" holding the dome down to distribute the pressure differential into more ground.
A massive building at the center of the dome. Heavy enough that it can hold down the forces even without anchors.

Do the maths. It would need to be a solid mass, not a building.

For example, for a 100m wide dome at 1atm, to counter the vertical component alone would require a central cylindrical block of solid steel 30m high, 30+m wide. (Or 50 high, 25 wide, if the dome is a hemisphere.)

I was replying to the suggestion of adding hold downs to the center of the dome. That would not require to hold down the full vertical component of the force. Part could still be done by anchors at the perimeter.  A 10m concrete and regolith structure would hold the forces for the area of the building. Add the mass of the building below and it can hold more. The 10m roof could expand  beyond the building and the structure may reduce the vertical forces at the perimeter by half.

Edit: the cylindrical structure I suggested before, would need a 10m roof plate to counter the full vertical pressure.

Er, if the "dome" is supposed to scale, the mid-dome anchors will need to be able to "support" at least the pressure between the mid dome anchors. Like an upside down, 3d suspension bridge of arbitrary size, you count on the edges for stability, but not additional strength.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2017 03:17 pm
Er, if the "dome" is supposed to scale, the mid-dome anchors will need to be able to "support" at least the pressure between the mid dome anchors. Like an upside down, 3d suspension bridge of arbitrary size, you count on the edges for stability, but not additional strength.

Your comment does not in any way invalidate the design I suggested.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 11/27/2017 03:52 pm
      One problem that I have with many designs presented here, involving domes, is not taking into account soil permeability.

      Simple put, unless your ENTIRE habitat is sealed up tight, atmosphere is going to leak through any exposed soil.

      I can't seem to understand why so many seem to think covering a crater with a dome would automatically make it a complete habitat.  If water can leak through the soil, the so will air.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2017 05:31 pm
      One problem that I have with many designs presented here, involving domes, is not taking into account soil permeability.

      Simple put, unless your ENTIRE habitat is sealed up tight, atmosphere is going to leak through any exposed soil.

      I can't seem to understand why so many seem to think covering a crater with a dome would automatically make it a complete habitat.  If water can leak through the soil, the so will air.

I wonder where you get that impression from. The necessity of some kind of seal at the bottom is obvious and it is trivial to do. So nobody thought of discussing it. That's my impression.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/27/2017 09:59 pm
The big tower, presented here some time last year.

Central radiation proof core, lateral growing/park areas, external walls held by the floors.  Basically a curtain wall building.  Likely to be very expensive!

Not really logical when you have a lot of horizontal real estate.


Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 11/28/2017 12:10 am
Er, if the "dome" is supposed to scale, the mid-dome anchors will need to be able to "support" at least the pressure between the mid dome anchors. Like an upside down, 3d suspension bridge of arbitrary size, you count on the edges for stability, but not additional strength.

Your comment does not in any way invalidate the design I suggested.
Then can you clarify your position from this quote?

I was replying to the suggestion of adding hold downs to the center of the dome. That would not require to hold down the full vertical component of the force. Part could still be done by anchors at the perimeter. 

You appear to be, not just suggesting, but outright stating, that the mid dome anchors do NOT need to support their fair share of the dome pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/28/2017 07:02 am
I am stating that a sufficiently heavy cover plate can balance part of the vertical pressure force. If the plate is ~10m thick it balances all the vertical force below it. That plate can be as large as the central building or can be larger.

Sure if so desired ground anchors below the building can be added.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 12/01/2017 01:18 pm
MIT's "Mars Redwood" city design team envisioned a pressurized sphere, half buried. It eliminated the dome/floor interface issues we've been discussing (yet again).

http://news.mit.edu/2017/mars-city-living-designing-for-the-red-planet-1031

I like their external mechanical pressure frame with an internal bladder, but I happen to think their design doesn't go far enough. Regolith should be used instead of beams imported from Earth.

We covered this for ages upthread (including the gothic architecture concepts): https://forum.nasaspaceflight.com/index.php?topic=34667.msg1355550#msg1355550







Title: Re: Envisioning Amazing Martian Habitats
Post by: saliva_sweet on 12/02/2017 11:57 am
MIT's "Mars Redwood" city design team envisioned a pressurized sphere, half buried. It eliminated the dome/floor interface issues we've been discussing (yet again).

http://news.mit.edu/2017/mars-city-living-designing-for-the-red-planet-1031

Not seeing the sphere on the illustration. In the link you provided they call them "domes" ... "anchored by tunneling roots". Spheres would need no anchoring. I don't know the details of their plan, just looking at the pics and the short text.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/02/2017 12:15 pm
Check out my "dream" for the aesthetics and functionality of an early-days Martian outpost:

https://www.youtube.com/watch?v=ee11pdMrjd0

Village of Dolceacqua ("Fresh water") in Italy.

This is a 360 degree video so you can grab any part of the image with your mouse and pan around.

Re: Dolceacqua, and the like.

I don't think any "early" settlement will look like a place that has been built and rebuilt for centuries. (Dolceacqua castle dates to at least the 12th Century. Presumably the old district has roots going back much, much further, still present in some of the walls and foundations.)

Evidently I am not saying that the Mars underground habitat will have the finish and visual aesthetics of a centuries-old town.

What I am referring to is the general shape and lay-out of the tunnel dwellings. When the initial tunneling has been performed there are just corridors and cave-like interior spaces. Those will have to be subdivided and the best way is obviously to use ISRU techniques. Locally produced bricks and cement would be best, and would lead to interior spaces perhaps reminiscent of what the Dolceacqua video shows.

High towers and domes and other outlandishly heavy structures, dependent on ridiculous amounts of material flown in from Earth, are obviously for a far-off future where a human space-faring civilisation (like "The Expanse") is already established.

We have to think in homesteader terms, not in highrise terms.   
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/02/2017 03:11 pm
Check out my "dream" for the aesthetics and functionality of an early-days Martian outpost:
I don't think any "early" settlement will look like a place that has been built and rebuilt for centuries.
Evidently I am not saying that the Mars underground habitat will have the finish and visual aesthetics of a centuries-old town.

Well, you did literally say that.

What I am referring to is the general shape and lay-out of the tunnel dwellings. When the initial tunneling has been performed there are just corridors and cave-like interior spaces. [...]
High towers and domes and other outlandishly heavy structures, dependent on ridiculous amounts of material flown in from Earth, are obviously for a far-off future [...]
We have to think in homesteader terms, not in highrise terms.

This gets back to my earlier point, the nature of the early settlement will depend more on other activities than what is the "best" habitat design. If you need to dig water from frozen aquifers, then tunnels will dominate simply because they are "free". If you need to scrape surface regolith to process out water, then cut'n'cover will dominate because that's the equipment you have. If you need to cut into a buried glacier, you might end up with some kind of wet habitat that KelvinZero has talked about.

Likewise, if you've got acres of solar panels (or a nuke) to power the fuel production, adding ten percent more in order to illuminate buried grow-rooms might be easier than having sun-exposed grow modules on the surface in addition to the needs of the excavation of water. However, if you get your water without major excavation (say drilling into that frozen aquifer, pumping in hot fluid, sucking out the meltwater), then the needs of your grow areas will dominate your hab design.

The actual living areas are a tiny, tiny part of the scale of activities and construction. So you need to answer the other questions before you can say, "Given that, what is the easiest way for them to add habitat volume."

For eg, the design of ISS is dominated by the limits of its construction (Shuttle payloads), then its power system, then the thermal system, then the lab requirements, and then and only then the "living area".
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/02/2017 11:12 pm
For eg, the design of ISS is dominated by the limits of its construction (Shuttle payloads), then its power system, then the thermal system, then the lab requirements, and then and only then the "living area".

Clearly the Mars habitat will be limited in the same way: by BFS payloads. However, unlike the ISS a Mars habitat will be built in a place with plenty of potential building material. So the BFS's should not carry building material but rather building equipment that can use the material already in place.

Elon Musk and many others have come to the conclusion that tunnels are the solution. He said so very clearly. That's why I think it is more interesting to read about ideas for underground habitats than other ideas. Domes, towers, spheres etc are all great fun but not too relevant for the first generations of a Mars base.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/03/2017 12:17 am
Elon Musk and many others have come to the conclusion that tunnels are the solution. He said so very clearly. That's why I think it is more interesting to read about ideas for underground habitats than other ideas. Domes, towers, spheres etc are all great fun but not too relevant for the first generations of a Mars base.

Elon Musk also mentioned geodesic domes with carbon fibre and glass panels.

Question from /u/Ulysius

As a follow-up, considering the synodal reuse of the ITS spaceships, what form of permanent habitation do you foresee? Shipped modules or an (eventual) shift to in-situ resource utilization such as Martian rigolith/plastic-reinforced concrete structures?

Thank you for your time.



Answer from /u/ElonMuskOfficial

Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 12/03/2017 07:05 am
Even if or especially if they all live underground, a dome with plants, a garden, will be a huge moral boost. A place to go to. Even knowing it exists and you could go to if you wish, will be a plus.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/10/2017 01:22 pm
MIT's "Mars Redwood" city design team envisioned a pressurized sphere, half buried. It eliminated the dome/floor interface issues we've been discussing (yet again).

http://news.mit.edu/2017/mars-city-living-designing-for-the-red-planet-1031

I like their external mechanical pressure frame with an internal bladder, but I happen to think their design doesn't go far enough. Regolith should be used instead of beams imported from Earth.

We covered this for ages upthread (including the gothic architecture concepts): https://forum.nasaspaceflight.com/index.php?topic=34667.msg1355550#msg1355550

Thanks :) I'm part of MIT's Redwood Forest City team so I can try to answer these, though the civil engineering work is not my area. I did the systems architecting and systems engineering, which included translating users' needs to the top level architectural requirements.

We did indeed select a half-buried sphere for its passive mechanical benefits. Each sphere (a.k.a. "dome") is connected to its own underground spaces and tunnels, and the tunnels are connected in a network, resulting in a city that is both above and below ground. The central feature of each "dome", the tree, provides additional structural strength and easy vertical transport of water, power and people to all levels of the habitat.

We don't import beams from Earth - ISRU is built in to the concept. As tunnels and underground spaces are being excavated the tailings are processed into water (and from there plastics), metals and structural building materials.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2017 01:32 pm
Lots of tunnels and a few domes, most of the tunnels for agriculture.
Acres and acres of solar panels and large underground tanks of water and propellant.

A few bravado buildings/structures.  because fun is part of life.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/10/2017 01:35 pm
MIT's "Mars Redwood" city design team envisioned a pressurized sphere, half buried. It eliminated the dome/floor interface issues we've been discussing (yet again).

http://news.mit.edu/2017/mars-city-living-designing-for-the-red-planet-1031

Not seeing the sphere on the illustration. In the link you provided they call them "domes" ... "anchored by tunneling roots". Spheres would need no anchoring. I don't know the details of their plan, just looking at the pics and the short text.

Sharp eyes :) The main structural elements of the sphere would wrap all the way around through the buried section to complete the sphere and give it its strength. That illustration doesn't show that. The structural tree provides anchoring because the sphere has large openings to the tunnel network at the bottom. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/10/2017 01:47 pm
Even if or especially if they all live underground, a dome with plants, a garden, will be a huge moral boost. A place to go to. Even knowing it exists and you could go to if you wish, will be a plus.

Right, and also since the dome has a high ceiling, you might as well give the inhabitants access to that third dimension. For example, the pizza & pasta joint can be a treehouse high up in the dome, with spectacular views out to the horizon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2017 01:54 pm
Even if or especially if they all live underground, a dome with plants, a garden, will be a huge moral boost. A place to go to. Even knowing it exists and you could go to if you wish, will be a plus.

Right, and also since the dome has a high ceiling, you might as well give the inhabitants access to that third dimension. For example, the pizza & pasta joint can be a treehouse high up in the dome, with spectacular views out to the horizon.
Like this then?   :-))
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 12/10/2017 02:12 pm
MIT's "Mars Redwood" city design team envisioned a pressurized sphere, half buried. It eliminated the dome/floor interface issues we've been discussing (yet again).

http://news.mit.edu/2017/mars-city-living-designing-for-the-red-planet-1031

I like their external mechanical pressure frame with an internal bladder, but I happen to think their design doesn't go far enough. Regolith should be used instead of beams imported from Earth.

We covered this for ages upthread (including the gothic architecture concepts): https://forum.nasaspaceflight.com/index.php?topic=34667.msg1355550#msg1355550

Thanks :) I'm part of MIT's Redwood Forest City team so I can try to answer these, though the civil engineering work is not my area. I did the systems architecting and systems engineering, which included translating users' needs to the top level architectural requirements.

We did indeed select a half-buried sphere for its passive mechanical benefits. Each sphere (a.k.a. "dome") is connected to its own underground spaces and tunnels, and the tunnels are connected in a network, resulting in a city that is both above and below ground. The central feature of each "dome", the tree, provides additional structural strength and easy vertical transport of water, power and people to all levels of the habitat.

We don't import beams from Earth - ISRU is built in to the concept. As tunnels and underground spaces are being excavated the tailings are processed into water (and from there plastics), metals and structural building materials.

Awesome! Glad to hear you are part of that effort!

I especially like MIT's mix of tunnels and airy spaces, and I can see from the illustrations how the tunneling machines are envisioned.

Very well done, even though I don't agree with all of it. My main beef is with the transparent geodesic domes. I just don't see them happening even if large open air spaces are created by some other means. (See my previous link).

Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 12/10/2017 02:21 pm
Lots of tunnels and a few domes, most of the tunnels for agriculture.
Acres and acres of solar panels and large underground tanks of water and propellant.

A few bravado buildings/structures.  because fun is part of life.

I've stated before that IMHO, agriculture will be present in every passage and facility (except where it poses a hazard) because as a general rule any system that can be distributed is safer than a centralized system.  Plus, there are other benefits to having a row of plants at waist height along every corridor.  It looks nice, it purifies air, it provides emergency food sources (in some cases) if/when access to parts of the facility is closed off because of an emergency.

Furthermore, I believe a diversity of small-scale food production by individual colonists will encourage the local economy and encourage a diversity of food sources. Each colonist will have their own cottage growing facilities where they make specialty crops or animals for consumption. Staple crops and animals will be grown in larger specialized facilities.  Thus the morel mushrooms and guinea pigs will be grown at home and traded or sold for locally brewed beer or cheese from another home. Large mono-culture farming or ranching facilities will be built and maintained by corporations for wheat, corn, rice, generic animal protein, etc.

https://forum.nasaspaceflight.com/index.php?topic=35877.msg1651890#msg1651890

All seems a moot point to me anyway.  Nobody would approve a mission that relies on the concept of agricultural success from the get-go. So you maintain at least one launch window's worth of stocks of food for everyone at all time, and continue to do so until local agriculture is proven reliable. Where's the problem?

I tend to agree, except that the problem is the cost of shipping and handling.  I think the least risky event is to supply a snod's worth of long duration food, and also establish crop growth facilities on Day 1.  That way in the event of a complete failure, you can abandon the place without a famine.

Secondly, and I've said this waaaaaay upthread, I think agriculture, and everything else up there will be distributed. The specialists will be cottage farmers who grow little bits of things that add up to a complete diet. Just like we did on Earth until the advent of highly mechanized farming.

In addition to large growing facilities for the staple nutritional crops, IMHO, there will be a talapia monger, a lettuce lady, the algae kids, the beer dude, etc.

I know that sounds romantic, but it's just how we divided food production labor for millennia.  Each of these items could fail on it's own without causing famine, but all of them are unlikely to fail at once (if the population is still alive).  A large single farm can easily be wiped out all at once.

To paraphrase "The Gripping Hand," will they cook, or will they just eat? Cuisine is at the very essence of a healthy culture. Without it, your're just visiting- or starving.

lamontagne, if you are willing to render a passage cut-away with planters growing a variety of trees and crops off to the side of the right-of-way, that'd be cool to see.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2017 09:05 pm
Added a lot of greenery.  Guess I could add more?  Is this enough, mr. Hill  :-)

I think some side tunnels will be entirely green, intensive agricultural areas, probably with some glass/ plastic separation to control the differences in humidity.

I expect the light 'strength' at the roof levels might be quite high, that would be good for plants, if not all that comfy for humans.

Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 12/10/2017 09:27 pm
Plants absorb red and blue light best, and obviously reflect green light. In commercial systems red and blue leds are used so the plants get just the wavelengths they need.

So in the side tunnels you could turn down the green to save some energy.

Interestingly the sun actually puts out the most light in green, so why are plants green...

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/11/2017 05:55 am
Interestingly the sun actually puts out the most light in green, so why are plants green...

Read a theory that it was because plants evolved late. Anaerobic slime-mats on the surface of lakes/seas glommed onto the rich creamy centre of the spectrum, leaving single-celled plants to grovel for the outer dregs that trickled past into deeper water.

[Edit: Yellow actually suppresses photosynthesis in many plants. By using select spectrum lights, you can increase the lighting levels beyond that of sunlight. Allowing better-than-best growth rates.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Long EZ on 12/28/2017 08:40 pm
Add a velodrome to the Mars colony site for great exercise! You could actually make your own g's, I calculated a 4.5 meter radius cylinder at 6.7 meters per second would make one g. Or how about having a circular path on the BFR so you could make your own g's while on the way to Mars. Get your exercise and g conditioning at the same time! I am thinking bicycles to get the necessary speed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: gin455res on 12/28/2017 09:37 pm
Add a velodrome to the Mars colony site for great exercise! You could actually make your own g's, I calculated a 4.5 meter radius cylinder at 6.7 meters per second would make one g. Or how about having a circular path on the BFR so you could make your own g's while on the way to Mars. Get your exercise and g conditioning at the same time!
https://www.youtube.com/watch?v=KuThmwYNBUc
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/29/2017 08:23 am
Add a velodrome to the Mars colony site for great exercise!
https://www.youtube.com/watch?v=KuThmwYNBUc

Somewhere between 20 and 25 RPM, around 1.5-2g combined. Running.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 12/29/2017 09:19 am
I dont see domes happening because of radiation. Domes are a staple of how a sci-fi colony looks like, but a more realistic design will be as much underground as possible. Especially if we are talking about an actual colony where people live and procreate long-term, and not just for six months.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 12/29/2017 10:22 am
Add a velodrome to the Mars colony site for great exercise! You could actually make your own g's, I calculated a 4.5 meter radius cylinder at 6.7 meters per second would make one g. Or how about having a circular path on the BFR so you could make your own g's while on the way to Mars. Get your exercise and g conditioning at the same time! I am thinking bicycles to get the necessary speed.

I'd like to see HPV's as a large part of Mars habitats. It's 'free' exercise when moving around.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/29/2017 11:06 am
HPV?

OK, a bit of sleuthing came up with human-powered vehicles... http://www.whpva.org/hpv.html

- I don't think you can count on that being an acronym people would know, though!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 12/29/2017 12:20 pm
- I don't think you can count on that being an acronym people would know, though!

Oops.  I didn't want to use bicycle as people immediately think diamond frame bikes.  That's a very narrow version of what a human powered vehicle can be.  There's not a practical need for in-habitat EV's for people or non industrial cargo.  Nothing's more that 30 minutes ride away on flat smooth surface. 

(although possibly would want automated delivery for light cargo, given workforce shortages).

Why waste batteries on EVs when you can have a simpler solution with secondary benefits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 12/29/2017 12:52 pm
I recognised HPV, but then I'm a fan of bikes etc.

Really good point with the bicycles to. I could quite easily see dockless ride share bikes being the main form of transport. Three wheel cargo electric bikes could also be made autonomous with just the addition of a smartphone and power steering and brakes. That gives you light cargo delivery plus independence for those unable (or unwilling) to peddle themselfs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: moreno7798 on 01/06/2018 04:36 am
I dont see domes happening because of radiation. Domes are a staple of how a sci-fi colony looks like, but a more realistic design will be as much underground as possible. Especially if we are talking about an actual colony where people live and procreate long-term, and not just for six months.

If you think about it, what is one of the most successful organisms in nature? Ants come to mind.

Deep underground habitats provide the perfect protection from radiation, climate, as well as space debris. On earth, this has been the case for ants. The deeper you go, the better off you'll be. Also, if it were up to me, I would put all food farms and equipment deep underground - again, protection is paramount. I do understand the need for a psychological outdoor-like space - perhaps for recreation. This could be the role of domes on Mars. Although, besides solar panels for power production, nothing of importance should be exposed at the surface until a mature colony has developed with enough materials and resources to quickly replace anything lost to natural disasters.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/06/2018 05:07 am
I dont see domes happening because of radiation. Domes are a staple of how a sci-fi colony looks like, but a more realistic design will be as much underground as possible. Especially if we are talking about an actual colony where people live and procreate long-term, and not just for six months.

If you think about it, what is one of the most successful organisms in nature? Ants come to mind.

Deep underground habitats provide the perfect protection from radiation, climate, as well as space debris. On earth, this has been for ants. The deeper you go, the better off you'll be. Also, if it were up to me, I would put all food farms and equipment deep underground - again, protection is paramount. I do understand the need for a psychological outdoor-like space - perhaps for recreation. Although, besides solar panels for power production, nothing of importance should be exposed at the surface until a mature colony has developed with enough materials and resources to quickly replace anything lost to natural disasters.

I absolutely see domes happening. Not like Elon Musk mentioned as the main habitats for people. But people have the need to look outside, not only through TV screens. So domes as a recreational area, places to go to to relax. Plants really don't suffer from that radiation level. Maybe seating areas can be covered with solid roofs but occasional exposure to these levels won't do harm. Robotbeat calculated that a 5 day 8 hour work schedule on the surface would not exceed radiation worker exposure limits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/09/2018 10:40 pm
Weirdly, the knowledge that domes are hugely difficult to build in a near-vacuum seems to disappear from this thread every two pages. The down-force needed on them is tremendous.

If you want domes it would be a better to have inverse, hanging domes with their structural weight counter-acting the suction of atmospheric near-vacuum. The structural strength of a dome acts inwards, not outwards.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/10/2018 12:41 am
The structural strength of a dome acts inwards, not outwards.

Not entirely. Domes still act as half-spheres to distribute internal pressure around the dome. Unfortunately, being half-spheres, you have in effect cut through all of the force-carrying great-circles, except the rim. So all of the distribution of force ends up pulling on the rim. That's why domes suck for internal pressure. (The same process is why domes (arches, etc) are so good at dealing with outside pressure and their own mass. The external force is neatly channelled outwards from the ceiling to the rim, then downwards into the foundations, instead of pulling down on a unsupported ceiling.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/10/2018 02:42 am
The structural strength of a dome acts inwards, not outwards.

Not entirely. Domes still act as half-spheres to distribute internal pressure around the dome. Unfortunately, being half-spheres, you have in effect cut through all of the force-carrying great-circles, except the rim. So all of the distribution of force ends up pulling on the rim.
That's not a problem, just use deep anchors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 01/11/2018 10:01 am
Here we go again !
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 01/11/2018 10:16 am
Here we go again !

Massive eye rolls from the audience!
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 01/12/2018 04:37 am
I can't tell.  Are his eyes tracing out a dome or a full sphere?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/12/2018 05:24 am
They are tracing out the words "don't go there, don't have that argument again, it's boring" on a screen perched halfway up the flat ceiling.

Which is really convenient, as that way I don't have to say it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 01/12/2018 05:45 pm
The latest stories about glaciers 300m thick just below the surface emphasize the idea that what you build as a habitat depends on the circumstances and local conditions.

Underground doesn’t have to be tunnels and small spaces. If you’re excavating water ice anyway it’s effectively free to make large underground spaces if you plan for them. If you build into glaciers that you want to locate near anyway the main architectural detail is the roof or cap you keep in place as you hollow out volume. That can be as massive as needed to retain atmosphere.

A volume 300m deep extending eventually for thousands of meters could be spacious enough to seem outdoors even though it’s underground. Water would be plentiful and could be used freely in design with lakes or waterfalls down the terraced sides of the rockface.

The objection that building a city in a glacier would be cold seems easily addressed since aerogels can be made with local materials and are excellent insulators so the warm inhabited volume could be separated from the ice face. Sunlight could be piped in or simulated.

The city would be started along the edge of a glacier so there’s a rock face and and an ice face that’s insulated and a growing volume between as ice is removed. The space would first grow down to the base of the glacier along the rock face. Habitats would be built in terraces on the rock face open to the excavated chamber and connected to tunnels and underground facilities on the other side.

The effect would be something like a very large spacious dome 1000’ tall but with habitations along the terraced rock face. Because it’s based on local features it’s cheaper to build than a dome and could be started and inhabited very early in a settlement and gradually expanded. The ongoing excavation of water ice to make propellant, water, oxygen would constantly expand the livable volume.

Most habitations would be on the terraced rockface so they have a side facing the “outdoor” volume and a side facing the rock. Every such dwelling or habitat could expand as needed underground. Utilities, storage, machinery could be located as needed on the underground side with the “outdoor” side left largely to be a beautiful public space. As the city grows it might also have buildings rising from the floor of the volume or even suspended from the roof.

This sort of city could have an O’Neill space colony sort of feel eventually with spacious vistas of enclosed volume with trees, rivers and landscaping, but actually grow organically like a traditional city without a predefined master plan inside a hull. Like an O’Neill colony it could locate farms, power plants, industry and anything it wants outside of view of the public spaces of the city. In this case by boring laterally into the rock face to create spaces for them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/12/2018 09:55 pm
Ludus,
You talk of green spaces and farming. Where do you envisage the light coming from? (O'Neill colonies have giant windows and mirrors, and orbit facing permanently at the sun.)

Concentrator-reflectors/light-pipes/etc don't work well on Mars, so for reflected light you are limited to 1:1 ratio of light:opening (ie, you can use a moving non-concentrator mirror to reflect sunlight into the opening, but it's only equivalent to having the same size opening facing the sun.) And if you use completely artificial light, you have the added power demand.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 01/12/2018 11:04 pm
Ludus,
You talk of green spaces and farming. Where do you envisage the light coming from? (O'Neill colonies have giant windows and mirrors, and orbit facing permanently at the sun.)

Some numbers.
Potatoes, for near-optimum production are fine at 75W/m^2 of current LED lights (with long days)
Assuming 500W of solar input at martian distance, and 25% efficiencies of solar, that's about 1.6m^2 of potatos per m^2 of noonday sun.
Assuming the equator, and seasons and stuff, you conservatively get .4m^2 of reasonable light per square meter of solar panels.
Even if you only cover the very surface of the habitat with solar panels, that is enough to light 40% or so of it to levels adequate for growing crops.

This level of illumination is also fine for any plant other than ones which absolutely require full sun. Purely decorative planting can go a lot lower.

 ( http://forum.nasaspaceflight.com/index.php?topic=43608.msg1766097#msg1766097 )
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dave G on 01/13/2018 05:23 pm
I dont see domes happening because of radiation. Domes are a staple of how a sci-fi colony looks like, but a more realistic design will be as much underground as possible. Especially if we are talking about an actual colony where people live and procreate long-term, and not just for six months.

Well said.  Or as Gwynne said at Stanford (https://www.flickr.com/photos/jurvetson/37659376821):
Quote from: Fireside Chat with SpaceX President Gwynne Shotwell, October 11, 2017
I don't think it's an accident that Elon started the Boring Company, tunnels will be very important in the first steps of living on Mars, before we build domes and terraform.

In other words, it won't be just domes, and it won't be just tunnels.  It will be both.  Domes for growing food.  Tunnels for living space that's shielded from space radiation.



Title: Re: Envisioning Amazing Martian Habitats
Post by: oiorionsbelt on 01/13/2018 05:45 pm
If there are indeed glaciers 300 meters thick just below the surface it seems like a real win win.
Tunnel into the glacier use tailings for ISRU, scoop out enough ice to build your dome such that the top of the dome is at the ceiling of the excavation. Leave just enough ice above the dome to support/hold down the dome and give enough radiation shielding yet let light through. No anchors required. Assumes of course the ice is at least somewhat transparent.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dave G on 01/13/2018 05:55 pm
If there are indeed glaciers 300 meters thick just below the surface it seems like a real win win.
Tunnel into the glacier use tailings for ISRU, scoop out enough ice to build your dome such that the top of the dome is at the ceiling of the excavation. Leave just enough ice above the dome to support/hold down the dome and give enough radiation shielding yet let light through. No anchors required. Assumes of course the ice is at least somewhat transparent.

1) Mars ice is mixed with soil.

2) Mars ice isn't transparent.

3) Mars ice evaporates (sublimes) quickly.  That's why it doesn't exist on the surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/13/2018 07:08 pm
I dont see domes happening because of radiation. Domes are a staple of how a sci-fi colony looks like, but a more realistic design will be as much underground as possible. Especially if we are talking about an actual colony where people live and procreate long-term, and not just for six months.

Well said.  Or as Gwynne said at Stanford (https://www.flickr.com/photos/jurvetson/37659376821):
Quote from: Fireside Chat with SpaceX President Gwynne Shotwell, October 11, 2017
I don't think it's an accident that Elon started the Boring Company, tunnels will be very important in the first steps of living on Mars, before we build domes and terraform.

In other words, it won't be just domes, and it won't be just tunnels.  It will be both.  Domes for growing food.  Tunnels for living space that's shielded from space radiation.
The space radiation risk is over-emphasized, though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dave G on 01/13/2018 07:50 pm
The space radiation risk is over-emphasized, though.

For radiation during space travel, I agree, mainly because:
 • Space travel times will be relatively short, i.e. months instead of years.
 • There are relatively easy ways to deal with it, for example:
     • Orient the spaceship so that there's a layer of water between the passengers and the the sun.
     • Have a small shielded room for temporary periods of high radiation.

For living on Mars, I think radiation is more serious, as evidenced by Gwynne's comment about the Boring Company.   Earth's liquid iron core produces a huge magnetic field which shields us from the vast majority of the sun's radiation.  What little radiation makes it past the Earth's magnetic shield, the vast majority of that is absorbed by our atmosphere.

By contrast, Mars has no liquid core, so there's no significant magnetic field, and Mar's atmosphere is only 1% of Earth's.  To be clear, if you're on the surface for a few hours here and there, that's probably OK.  But if you spend all or most of your time exposed to Mars surface radiation, that would probably be bad.

Note that there are schemes to shield areas of the surface from radiation using magnetism, but this would require large amounts of energy, i.e. a fairly large nuclear power plant.
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 01/13/2018 08:35 pm
I believe that the solar incoming in space is multidirectional so orienting the ship behind one wall of water won't help.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dave G on 01/13/2018 09:40 pm
I believe that the solar incoming in space is multidirectional so orienting the ship behind one wall of water won't help.

I may be remembering it wrong, but I thought the constant solar solar radiation was fairly directional, while the really dangerous radiation from big solar flares tended to come at you from multiple directions, hence the need for a small room that's shielded from all angles.

Does anyone have links with more specific info on whether or not various types of solar radiation are directional?
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 01/13/2018 11:52 pm
I believe that the solar incoming in space is multidirectional so orienting the ship behind one wall of water won't help.

I may be remembering it wrong, but I thought the constant solar solar radiation was fairly directional, while the really dangerous radiation from big solar flares tended to come at you from multiple directions, hence the need for a small room that's shielded from all angles.

Does anyone have links with more specific info on whether or not various types of solar radiation are directional?

Could be that I'm confused.  As you say, we need links.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/14/2018 01:01 am
I dont see domes happening because of radiation. Domes are a staple of how a sci-fi colony looks like, but a more realistic design will be as much underground as possible. Especially if we are talking about an actual colony where people live and procreate long-term, and not just for six months.

In our Redwood Forest design, the underground part will likely end up being much larger than the overground part because the marginal effort to expand underground will be much less than expansion overground. Also, by the functional allocation and designated use of spaces, people will end up spending most of their time underground.

For the overground part, the upper-inside part of the spherical domes is lined with water cells to cut most of the incoming radiation. At low elevation angles, the much larger "atmospheric cylinder" mass** compensates for the lack of water shielding.

** : see http://www.boulder.swri.edu/~rafkin/rafkin_etal_radpress_2014.pdf (http://www.boulder.swri.edu/~rafkin/rafkin_etal_radpress_2014.pdf), total radiation dose on Mars is inversely proportional to atmospheric column mass, with heavy ions disproportionately affected.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/14/2018 01:17 am
The space radiation risk is over-emphasized, though.
For living on Mars, I think radiation is more serious, [...]
By contrast, Mars has no liquid core, so there's no significant magnetic field, and Mar's atmosphere is only 1% of Earth's. To be clear, if you're on the surface for a few hours here and there, that's probably OK. But if you spend all or most of your time exposed to Mars surface radiation, that would probably be bad.

Robotbeat's point is that we have actual data of radiation levels on the surface of Mars thanks to Curiosity. It's greatly reduced compared to deep space, around a third, ending up around a third higher than ISS. (So 500 days on the surface gives an equivalent dosage of a 180 day transit, or 2 years in LEO.)

Although I will add that Curiosity's Radiation Assessment Detector is a limited test; biological effects are... complex, and not necessarily predicted by simple particle counts. Importantly, most high-energy cosmic radiation will be reduced to secondary radiation by impacting the upper Martian atmosphere before it hits any shielding (rather than inside the shielding), that means all of the remaining radiation should be blocked by a fairly small amount of shielding. [Edit: Nope, I remembered that backwards. Cosmic rays are largely unaffected by the Martian atmosphere. Heavy (solar) ions are strongly affected.]

So if you work in an unshielded area on the surface during the day, then sleep in a lightly shielded bunker (protected by a foot or two of concrete/rock/etc), you shouldn't experience any more cumulative radiation than someone living at high altitudes on Earth. [Edit: So, "it's complicated".]



[There are all sorts of weird interactions. Eg. Surface radiation is lower during the day, because solar heating thickens the atmosphere compared to the cooler atmosphere at night. Another reason to stay inside at night.]

(https://i0.wp.com/www.spacesafetymagazine.com/wp-content/uploads/2012/11/radiation-pressure-mars-graph.jpg) (https://i0.wp.com/www.spacesafetymagazine.com/wp-content/uploads/2012/11/radiation-pressure-mars-graph.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/14/2018 01:18 am
Ludus,
You talk of green spaces and farming. Where do you envisage the light coming from? (O'Neill colonies have giant windows and mirrors, and orbit facing permanently at the sun.)

Concentrator-reflectors/light-pipes/etc don't work well on Mars, so for reflected light you are limited to 1:1 ratio of light:opening (ie, you can use a moving non-concentrator mirror to reflect sunlight into the opening, but it's only equivalent to having the same size opening facing the sun.) And if you use completely artificial light, you have the added power demand.

Agriculture on Mars can't be designed to rely on sunlight because of the "Dust-storm Winter" effect. Therefore, artificial light is the way to go.

Adding the energy requirement for agricultural lighting to all the other energy requirements for life support, ISRU, manufacturing etc. leads to the easy conclusion that when it comes to designing Mars colonies, you go power-rich or go home.

Hence, a real Mars colony will likely rely primarily on nuclear power, with solar cells as a backup or secondary technology.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dave G on 01/14/2018 03:13 am
Agriculture on Mars can't be designed to rely on sunlight because of the "Dust-storm Winter" effect. Therefore, artificial light is the way to go.
Why does it have to be one or the other?  I suspect a mix of natural and artificial lighting would work best, i.e. transparent domes with additional overhead LED lighting.  It's more reliable to have 2 different types of light sources, should anything go wrong with either.

Hence, a real Mars colony will likely rely primarily on nuclear power, with solar cells as a backup or secondary technology.
I see solar and nuclear as complementary.  Nuclear can provide constant baseline power 24/7.  Solar can provide additional power during the day.  Batteries can also help even things out, but I don't think you need 24 hours of batteries.  2-4 hours of storage should be enough.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/14/2018 03:26 am
Ludus,
You talk of green spaces and farming. Where do you envisage the light coming from? (O'Neill colonies have giant windows and mirrors, and orbit facing permanently at the sun.)

Concentrator-reflectors/light-pipes/etc don't work well on Mars, so for reflected light you are limited to 1:1 ratio of light:opening (ie, you can use a moving non-concentrator mirror to reflect sunlight into the opening, but it's only equivalent to having the same size opening facing the sun.) And if you use completely artificial light, you have the added power demand.

Agriculture on Mars can't be designed to rely on sunlight because of the "Dust-storm Winter" effect. Therefore, artificial light is the way to go.

Adding the energy requirement for agricultural lighting to all the other energy requirements for life support, ISRU, manufacturing etc. leads to the easy conclusion that when it comes to designing Mars colonies, you go power-rich or go home.

Hence, a real Mars colony will likely rely primarily on nuclear power, with solar cells as a backup or secondary technology.
Exactly.

A good sized front loader is 700 HP, or half a MWatt.  Which on Mars is a MWatt-sized field.

And said tractor can now only work a few hours a day with that field.

And people are talking TBMs...

Power is the biggest missing piece in all of the Mars plans, and the only scalable solution is nuclear.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 01/14/2018 03:47 am
Ludus,
You talk of green spaces and farming. Where do you envisage the light coming from? (O'Neill colonies have giant windows and mirrors, and orbit facing permanently at the sun.)

Concentrator-reflectors/light-pipes/etc don't work well on Mars, so for reflected light you are limited to 1:1 ratio of light:opening (ie, you can use a moving non-concentrator mirror to reflect sunlight into the opening, but it's only equivalent to having the same size opening facing the sun.) And if you use completely artificial light, you have the added power demand.

Agriculture on Mars can't be designed to rely on sunlight because of the "Dust-storm Winter" effect. Therefore, artificial light is the way to go.

Adding the energy requirement for agricultural lighting to all the other energy requirements for life support, ISRU, manufacturing etc. leads to the easy conclusion that when it comes to designing Mars colonies, you go power-rich or go home.

Hence, a real Mars colony will likely rely primarily on nuclear power, with solar cells as a backup or secondary technology.

I assume a power rich settlement with reactors that it cools with water that also keeps the large pseudo outdoor volume warm.

My assumption for a city built into the edge of a glacier, underground, would be that agriculture would be outside the city volume, mostly vertical Ag with LEDs in excavated space linked to the city. Things like agriculture and industry would be tunneled to behind the cliff.

As far as light in the city, the city has a sort of artificial Sky across from the terraced cliff face its built on. It would cover an arc including the ice face of the glacier that’s covered in aerogel insulation and LEDs that extends to include the roof.

The effect might be something like a city on the Amalfi coast or Liguria in Italy built up a cliff and looking out to the sea and sky.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 01/14/2018 03:49 am
Agriculture on Mars can't be designed to rely on sunlight because of the "Dust-storm Winter" effect. Therefore, artificial light is the way to go.

Adding the energy requirement for agricultural lighting to all the other energy requirements for life support, ISRU, manufacturing etc. leads to the easy conclusion that when it comes to designing Mars colonies, you go power-rich or go home.

Hence, a real Mars colony will likely rely primarily on nuclear power, with solar cells as a backup or secondary technology.

Doesn't quite follow.
If you have efficient ISRU going to methane and oxygen, you can simply run that process backwards to get power out at a moderate efficiency, meaning coping with dust storms lasting a month is basically trivial as you have a years backup power.

Not that big nuclear wouldn't be nice of course.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 01/14/2018 04:10 am
Ludus,
You talk of green spaces and farming. Where do you envisage the light coming from? (O'Neill colonies have giant windows and mirrors, and orbit facing permanently at the sun.)

Concentrator-reflectors/light-pipes/etc don't work well on Mars, so for reflected light you are limited to 1:1 ratio of light:opening (ie, you can use a moving non-concentrator mirror to reflect sunlight into the opening, but it's only equivalent to having the same size opening facing the sun.) And if you use completely artificial light, you have the added power demand.

Reactors. ONeill Colonies just seemed like a common reference to designs with large pseudo outdoor spaces with trees and beaches. There have also been similar designs in hollowed out asteroids that have no external light. I don’t think designs for cities intended to eventually have hundreds of thousands of people can be attractive without a plentiful concentrated power source.

Lava tubes might provide large underground volumes but don’t seem to be where the water is, and constructed spaces would be safer. Cities should be where there’s plentiful water and it’s going to excavated and used up anyway so why not use the underground volume created? I’m not a civil engineer or architect but it seems likely they could come up with a plan for an expandable roof over this growing pit on the edge of a glacier.

There’s an intuitive idea that a city that’s surrounded by ice would be cold but with good insulation like aerogel that can be locally made, the city could have palm trees and tropical plants and the ice face of the glacier could look like the sea and sky in the distance.

The sea might be something like this, from a company called “Crystal Lagoons”. They already have designs to use these for cooling power plants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/14/2018 04:38 am
Agriculture on Mars can't be designed to rely on sunlight because of the "Dust-storm Winter" effect.

Not necessarily. Plants can use diffuse light as easily as direct light. And even during the worst dust storms, total light available is still around a third as much as during the clearest skies, even though direct sunlight drops below 1%. [Same with modern solar panels.]

IMO, the complexity in using natural light for agriculture is the conflict between needing high transparency walls for the plants, against needing high thermal insulation to deal with the day/night, summer/winter temperature variations. (Even the thin Martian atmosphere is surprisingly effective at conducting/convecting heat away from a surface. At just a few km/h wind-speed, it becomes the dominant form of heat loss.) Whatever your solution for that, I suspect it will always be easier/cheaper to just add more power for artificial lighting.

Adding the energy requirement for agricultural lighting to all the other energy requirements for life support, ISRU, manufacturing etc. leads to the easy conclusion that when it comes to designing Mars colonies, you go power-rich or go home.

Yes. The needs of propellant production will dominate the power use for the entire settlement. With artificial-light for intensive agriculture a fraction of that. And everything else down in the rounding-off error.

But IMO that factor also helps with solar panels. If propellant production can be slowed or suspended during dust-storm-season, that frees up enough power for all-year agriculture. At absolute worst case, there might be a few days during decadal mega-storms, where you need to let the plants go dormant in order to have enough power for night-time use of the habitats-proper.

Hence, a real Mars colony will likely rely primarily on nuclear power, with solar cells as a backup or secondary technology.

Again, not necessarily. Solar power, batteries, etc are continuously developed to cater to Earth markets, Mars (and other space users) can therefore piggyback on that research-funding/commercial-development. Space-rated, modular nuclear power has virtually no Earth market to date, and development of nuclear power is still focused on traditional reactor designs. Therefore, almost the entire cost of research and development will need to be borne by the space users. Adding an extra billion dollars to your R&D cost weighs poorly against just buying a billion dollars worth of extra panels/storage and their transport.

Don't get me wrong, if you can just buy an off-the-shelf, plug'n'play, zero-maintenance, walk-away-safe, multi-megawatt reactor to use on Mars, why wouldn't you? But if that doesn't exist, it will likely always be cheaper, easier, safer and more effective to just buy more solar/storage.



(Aside: Some of this is probably better suited to the Scaling-Ag thread, or similar.)



Lava tubes might provide large underground volumes but don’t seem to be where the water is

If the average (day/night/summer/winter) ground temperature at that site is below freezing, then the constant temperature in the lava tube will also be below freezing, and so they will collect water ice in the same way that the poles do.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dave G on 01/14/2018 04:57 am
Don't get me wrong, if you can just buy an off-the-shelf, plug'n'play, zero-maintenance, walk-away-safe, multi-megawatt reactor to use on Mars, why wouldn't you?

Does the technology Bill Gates is working on have any applicability here?  http://terrapower.com/about

From what I've heard, you just bury it in the ground and let it do it's thing.  Lasts 50-60 years.

They're pitching this for third world countries. As I understand it, the main target is smaller villages with no electricity.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 01/14/2018 06:07 am
This might well have been brought up before, but in light of mass and power restrictions I was wondering if a slow downward expansion of internal space would be preferable.  The beginning core building would be designed to have enough mass or anchoring to sustain pressure.  Once secured and the floors adequately sealed, excavation below could continue at a pace determined by the size of equipment available and power limitations.  This notion in some ways would resemble the way that TBM's drill and add structure continuously.

The rubble would need to be removed from above and likely through the existing floors which would be noisy and unfit for living spaces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: mgeagon on 01/14/2018 06:35 am
There’s an intuitive idea that a city that’s surrounded by ice would be cold
Ice is no colder than its surroundings. In fact, it is a pretty efficient insulator rather than conductor. I have personally been very cozy inside igloos. The issue will be with structural stability, as density is doubled by melting. This has been dealt with on Earth for centuries. With human activity (ie. warm) fresh water will flow, so colonizing inside a glacier is an elegant solution.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/14/2018 07:27 am
TripD/etc,

What is the purpose of the volume you are creating? Is it just living space?

Something that was just brought up again in relation to power demand, and I might as well repeat an observation I made earlier about habitat construction:

- The main industrial activity for your settlement, for a long, long time, will be ISRU propellant production. Hence how you get water will be the biggest predictor of the type of equipment, skills, material, etc that you will have available.

- OTOH, the biggest requirement for pressurised volume will be agriculture. Many many times the size of your living space.

- Hence your living space will be a small side-area off of your agricultural volume, which will be built using whatever equipment you need to get water, and whatever materials are surplus/waste from that process.

[Even once you've expanded to the point where specialist housing construction makes sense, this early habitation will still set the standard for later construction, because it will have set the demand for parts/equipment for the first on-Mars manufacturing, and hence be the lowest cost systems available for later development. The size of the Channel Tunnel was ultimately set by the width of the arses of Napoleon's horses, so the joke goes.]

People seem to picture everything in reverse order. First your big living area. Then some small ag spaces off the side, tucked out of the way. Then, as an afterthought, somewhere completely out-of-sight, a little module that manufactures propellant.

Ludus, at least, puts the water-source first. But he then focuses on living space. Whereas Ag-volume is next, by an order of magnitude.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/14/2018 05:31 pm
Ludus, the Amalfi-like giant ice cave is a beautiful concept and it reminds me of Zygote in the Mars trilogy :) Was that your inspiration?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 01/14/2018 05:34 pm
TripD/etc,

What is the purpose of the volume you are creating? Is it just living space?

Something that was just brought up again in relation to power demand, and I might as well repeat an observation I made earlier about habitat construction:

- The main industrial activity for your settlement, for a long, long time, will be ISRU propellant production. Hence how you get water will be the biggest predictor of the type of equipment, skills, material, etc that you will have available.

- OTOH, the biggest requirement for pressurised volume will be agriculture. Many many times the size of your living space.

- Hence your living space will be a small side-area off of your agricultural volume, which will be built using whatever equipment you need to get water, and whatever materials are surplus/waste from that process.

[Even once you've expanded to the point where specialist housing construction makes sense, this early habitation will still set the standard for later construction, because it will have set the demand for parts/equipment for the first on-Mars manufacturing, and hence be the lowest cost systems available for later development. The size of the Channel Tunnel was ultimately set by the width of the arses of Napoleon's horses, so the joke goes.]

People seem to picture everything in reverse order. First your big living area. Then some small ag spaces off the side, tucked out of the way. Then, as an afterthought, somewhere completely out-of-sight, a little module that manufactures propellant.

Ludus, at least, puts the water-source first. But he then focuses on living space. Whereas Ag-volume is next, by an order of magnitude.

For me the purpose of the volume created is “Amazing Martian Habitat”. It would be a cool place to live rather like the French or Italian Riviera. It doesn’t have any above ground structure or any necessary natural light while seeming very outdoor and naturally lit.

Agriculture space I see as just a variant of industrial space that’s built underground as needed.If people don’t live in it, it can just be chambers hollowed out of rock linked by tunnels. I guess the theme would be design that drops natural sunlight as a important criterion for a desirable place to live.

The cliff side city space is everywhere connected to underground utility spaces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 01/14/2018 05:38 pm
Ludus, the Amalfi-like giant ice cave is a beautiful concept and it reminds me of Zygote in the Mars trilogy :) Was that your inspiration?

Thanks. You mean Robinson’s trilogy? No, but I should move that up on my reading list.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/14/2018 06:07 pm
One thing to note is that the concepts for agriculture, amount & type of energy required and type of habitat (over / under ground) must all be co-determined and cannot be chosen independently.

A village-size habitat that is mostly underground, with distributed hydroponic farming based mostly on artificial light and an energy source that is mostly distributed nuclear (https://www.nasa.gov/directorates/spacetech/kilopower (https://www.nasa.gov/directorates/spacetech/kilopower)) is a feasible, scalable, and relatively uncomplicated & reliable solution that checks many of the boxes of what is a good system architecture for a large habitat on Mars.

The Redwood Forest concept builds on this baseline, adding the overground domes which provide visual access to the real outdoors and a place for organic smallholder "personal farming" using natural sunlight. Such overground domes mainly serve psychological purposes, but this is not to diminish these purposes. With a hostile planet outside, the contribution to psychological wellness will be a critically important attribute of any amazing habitat on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 01/14/2018 06:43 pm

A village-size habitat that is mostly underground, with distributed hydroponic farming based mostly on artificial light and an energy source that is mostly distributed nuclear (https://www.nasa.gov/directorates/spacetech/kilopower (https://www.nasa.gov/directorates/spacetech/kilopower))

Sounds great. However, single Kilopower reactor is only 1 to 10 KWe. How many MWe would be required to lets say, have enough artificial light to reliably feed a dozen people on Mars and also fill up a BFS with ISRU propellant? That seems like a lot of Kilopowers..
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 01/14/2018 07:12 pm
Quote
What is the purpose of the volume you are creating? Is it just living space?

Your point is taken.  I was just suggesting an overall method for expansion.  I was imagining the benefits of working within a somewhat protected space.   

As you said living space would need the least expansion and I don't think would fit well with an ongoing work. Any other usage would be tolerant of continued work.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/14/2018 07:13 pm
Yeah, and at least some shielding can be done by filling the transparent panels with water or making them out of thick clear plastic.

People seem to act as if no level of radiation above sea level Earth in any part of the habitat is acceptable, therefore they make ridiculous assumptions about the required thickness of shielding.. But that's simply not true. We wouldn't get dental X-rays or CT scans or live in places like Denver or Lima, Peru, etc. We wouldn't take airline flights.

We can make a transparent dome-like structure well enough shielded that people could spend hours every day without unacceptable radiation levels. Heck, Americans tend to spend only 7% of their life outdoors, so if the transparent dome (and perhaps EVA) is the "outdoors" of Mars, then at the 0.67mSv/day, Mars settlers will only get 17mSv/year. We could improve that a lot just by adding a couple feet of water in addition to the structure in the dome's panels, bringing it to just 5mSv/year (or 3.75mSv over 9 months), which is an acceptably low level for nearly all purposes provided people spend a "normal" amount of time in the dome vs "inside."

Radiation workers can get up to 50 mSv/year. Even pregnant women are allowed 5mSv for the duration of their pregnancy.


So very well-shielded tunnels can serve as the indoors with the less-well-shielded (but still good enough) dome serving as the outdoors, and everyone including pregnant women and children (5mSv/year limit) would be well enough protected provided they get the "normal" amount of time indoors.

Of course, if you normally get 5mSv/year indoors, then you can afford to "spend" about 45mSv/year on EVAs. That's a lot, actually. The daily dose on the surface of Mars is about 0.67mSv/day, or .028mSv/hour. That means the typical adult can spend over 1600 hours per year outside doing EVAs with effectively no additional shielding. Assuming a typical 250 day work-year, that means each work-day, you can spend over 6.4 hours doing unshielded EVAs. Out of a typical 8 hour workday, that's pretty good for JUST outside work! And that's IN ADDITION to the 7% of time spent "outdoors" in the less-well-shielded dome.

...the consequence of that is that some domes could have ZERO extra shielding and people could still spend like 5-6 hours a day in them without going over limits. I expect most people won't be doing EVAs.

So again, I think the radiation concerns are over-blown. As long as most time spent "indoors" is well-shielded, there's no reason that every dome has to be shielded with 30 feet of water or whatever. Just 2 or 3 feet would allow even children to spend a significant amount of time in them every day, and adults wouldn't need even that much shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/14/2018 07:13 pm

A village-size habitat that is mostly underground, with distributed hydroponic farming based mostly on artificial light and an energy source that is mostly distributed nuclear (https://www.nasa.gov/directorates/spacetech/kilopower (https://www.nasa.gov/directorates/spacetech/kilopower))

Sounds great. However, single Kilopower reactor is only 1 to 10 KWe. How many MWe would be required to lets say, have enough artificial light to reliably feed a dozen people on Mars and also fill up a BFS with ISRU propellant? That seems like a lot of Kilopowers..
...that's why solar is likely to be the predominant power source on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/14/2018 10:56 pm
Well said.  Or as Gwynne said at Stanford (https://www.flickr.com/photos/jurvetson/37659376821):
Quote from: Fireside Chat with SpaceX President Gwynne Shotwell, October 11, 2017
I don't think it's an accident that Elon started the Boring Company, tunnels will be very important in the first steps of living on Mars, before we build domes and terraform.

In other words, it won't be just domes, and it won't be just tunnels.  It will be both.  Domes for growing food.  Tunnels for living space that's shielded from space radiation.

What she said makes it quite clear that tunnels are what we will see in the first years of Mars habitats. "Before we build domes and terraform" distinctly makes domes sound as a far-off thing. Which makes eminent sense.

Logic dictates that the first years of creating substantial spaces on Mars (beyond shipped-in pre-fabs) will be tunnels and subterranean spaces. You just can't afford to bring building materials to Mars. You instead bring building equipment and carve out the abundant bedrock already in place.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/15/2018 02:38 am
I've read upthread, multiple times, that ISRU propellant energy costs will dominate the power budget.

I even probably wrote the same thing.

But now I'm thinking this may not be true.

A large front loader or excavator runs half a MWatt engine. Construction activities are pretty power hungry.

Agriculture, if you need to illuminate large patches of ground, is also MWatt-scale. (Ask any basement pot grower)

Earth insolation is 1 kWatt/m2, and I wonder how many m2 are required to feed a person year round.

http://www.farmlandlp.com/2012/01/one-acre-feeds-a-person/

Wow.

---

Someone did the math here before (RB?) But how much again was 1BFS/synode?
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 01/15/2018 03:05 am
I've read upthread, multiple times, that ISRU propellant energy costs will dominate the power budget.

I even probably wrote the same thing.

Agriculture, if you need to illuminate large patches of ground, is also MWatt-scale. (Ask any basement pot grower)

Earth insolation is 1 kWatt/m2, and I wonder how many m2 are required to feed a person year round.

Plants don't require nearly that amount, for several reasons. (an acre-kilowatt)

http://forum.nasaspaceflight.com/index.php?topic=43608.msg1766097#msg1766097 - potatos can feed one person enough calories to live on about 3kW.
6kW gets you assorted other plants in the diet quite freely, and 8kW lets you add a bit of meat. (pigs can convert calories in to pork at ~9%). (all average)
ISRU, as a comparison, to generate a couple of hundred tons of methane you need about (average) 600kW for a year.

So, if you can return 100 people to earth, that's 6kW*year-per person, or about the same for growing a mixed vegetarian diet.

http://forum.nasaspaceflight.com/index.php?topic=43608.msg1727087#msg1727087 refers to a process which enables you to go from methane -> food at 25% efficiency which might in principle supplement diet and reduce power usage on farming, as it's around 10* as efficient but not very palatable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 01/15/2018 03:34 am

http://forum.nasaspaceflight.com/index.php?topic=43608.msg1727087#msg1727087 refers to a process which enables you to go from methane -> food at 25% efficiency which might in principle supplement diet and reduce power usage on farming, as it's around 10* as efficient but not very palatable.

Filter it through a pig or chicken or fish to improve taste. At 10 times the efficiency still a deal. Or grow algae with natural sunlight in a relatively cheap setup and filter that through some animals.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/15/2018 03:46 am
I've read upthread, multiple times, that ISRU propellant energy costs will dominate the power budget.

I even probably wrote the same thing.

Agriculture, if you need to illuminate large patches of ground, is also MWatt-scale. (Ask any basement pot grower)

Earth insolation is 1 kWatt/m2, and I wonder how many m2 are required to feed a person year round.

Plants don't require nearly that amount, for several reasons. (an acre-kilowatt)

http://forum.nasaspaceflight.com/index.php?topic=43608.msg1766097#msg1766097 - potatos can feed one person enough calories to live on about 3kW.
6kW gets you assorted other plants in the diet quite freely, and 8kW lets you add a bit of meat. (pigs can convert calories in to pork at ~9%). (all average)
ISRU, as a comparison, to generate a couple of hundred tons of methane you need about (average) 600kW for a year.

So, if you can return 100 people to earth, that's 6kW*year-per person, or about the same for growing a mixed vegetarian diet.

http://forum.nasaspaceflight.com/index.php?topic=43608.msg1727087#msg1727087 refers to a process which enables you to go from methane -> food at 25% efficiency which might in principle supplement diet and reduce power usage on farming, as it's around 10* as efficient but not very palatable.

So even under the numbers you quote (which I think are a bit optimistic), food at least competes with propellant ISRU.

Which would make sense.  A person at rest is a constant 100 Watt consumer I believe.  Factor in the efficiency of metabolism, and the fact that you're not always at rest, and then the efficiency of the agriculture producing the food, and it adds up to near what that BFS needs, per person.

And what about the machines the person operates?  The construction equipment, driving around, excavating soil and ice, processing soil...

I think the assumption that propellant ISRU will dominate is erroneous.  Might be true for the first couple of years, but if we're truly shooting for a colony, day-to-day survival and growth activities will quickly equal and then surpass propellant ISRU. (keeping it on a per-person basis, so accounting for the increase in BFS launch rate)

It's just that the more advanced the colony, the more activities will be performed in-situ, (e.g. a cement plant, a glass plant, copper plant...) and the power budget will keep going up.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/15/2018 03:51 am
Well said.  Or as Gwynne said at Stanford (https://www.flickr.com/photos/jurvetson/37659376821):
Quote from: Fireside Chat with SpaceX President Gwynne Shotwell, October 11, 2017
I don't think it's an accident that Elon started the Boring Company, tunnels will be very important in the first steps of living on Mars, before we build domes and terraform.

In other words, it won't be just domes, and it won't be just tunnels.  It will be both.  Domes for growing food.  Tunnels for living space that's shielded from space radiation.

What she said makes it quite clear that tunnels are what we will see in the first years of Mars habitats. "Before we build domes and terraform" distinctly makes domes sound as a far-off thing.
...
Far-off? Nah, that's reading way too much into it.

The original ITS had basically half a dome built-in, and ITS was to be the first habitat. BFS has slightly different/smaller windows, but much the same deal.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/15/2018 07:33 am
the agriculture producing the food, and it adds up to near what that BFS needs, per person.

Not quite. Remember that for each crew ship there will be several cargo ships which all need to go back to Earth too. (10:1 was thrown around in the early days.)

And what about the machines the person operates?  The construction equipment, driving around, excavating soil and ice, processing soil...

I was including that in the "cost of propellant production", not just the propellant manufacture itself. Everything that goes into feeding the beast. That's also what I meant about it dictating the resources you will have available for building pressurised volume. If you need to scrape the regolith, you'll have regolith diggers and haulers, and way too much waste regolith. So cut'n'cover seems obvious. If you are digging underground, you will live in those spaces, because rock-cutters are your main equipment and mines are your primary excavated volume. If you are melting through lightly buried glaciers, that dominates your equipment/volume/thinking. And so on.

And I accept that, eventually, broader industry will replace propellant as the main energy users. But the pattern will remain. The largest activity will be industry. The largest pressurised area and second largest power and materials user will be agriculture. The actual living area will be a small add-on, by comparison.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/15/2018 08:48 am
the agriculture producing the food, and it adds up to near what that BFS needs, per person.

Not quite. Remember that for each crew ship there will be several cargo ships which all need to go back to Earth too. (10:1 was thrown around in the early days.)

And what about the machines the person operates?  The construction equipment, driving around, excavating soil and ice, processing soil...

I was including that in the "cost of propellant production", not just the propellant manufacture itself. Everything that goes into feeding the beast. That's also what I meant about it dictating the resources you will have available for building pressurised volume. If you need to scrape the regolith, you'll have regolith diggers and haulers, and way too much waste regolith. So cut'n'cover seems obvious. If you are digging underground, you will live in those spaces, because rock-cutters are your main equipment and mines are your primary excavated volume. If you are melting through lightly buried glaciers, that dominates your equipment/volume/thinking. And so on.

And I accept that, eventually, broader industry will replace propellant as the main energy users. But the pattern will remain. The largest activity will be industry. The largest pressurised area and second largest power and materials user will be agriculture. The actual living area will be a small add-on, by comparison.
Good point about the multiple cargo ships
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/19/2018 03:47 am
What is the energy budget on earth? I think industry is dominant here (but I'm guessing)[1]... this supports the thesis that it will be that way on Mars too.

1 - support factoid, supposedly it takes as much energy to make a car as it does to fuel it for an average lifetime. No cite, just a factoid I remember...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/19/2018 03:59 am
What is the energy budget on earth? I think industry is dominant here (but I'm guessing)[1]... this supports the thesis that it will be that way on Mars too.

1 - support factoid, supposedly it takes as much energy to make a car as it does to fuel it for an average lifetime. No cite, just a factoid I remember...
Your factoid is off by about a factor of 4. If the car lasts 100,000 miles (and they often last much longer), then the embodied energy is only about 22% of the total energy:
http://energyskeptic.com/2015/how-much-energy-does-it-take-to-make-a-car-by-david-fridley-lbl/
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/19/2018 04:36 am
What is the energy budget on earth? I think industry is dominant here (but I'm guessing)[1]... this supports the thesis that it will be that way on Mars too.

1 - support factoid, supposedly it takes as much energy to make a car as it does to fuel it for an average lifetime. No cite, just a factoid I remember...
Your factoid is off by about a factor of 4. If the car lasts 100,000 miles (and they often last much longer), then the embodied energy is only about 22% of the total energy:
http://energyskeptic.com/2015/how-much-energy-does-it-take-to-make-a-car-by-david-fridley-lbl/

I knew I shouldn't have kept my last car 196K miles then!

Anyway I am agreeing with those who think it likely that on Mars, as on Earth now, industrial and ag are the major energy consumers followed by transport with residential somewhere in the way back... Transport may be more in the early days but that will diminish...
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 01/21/2018 08:29 am

So even under the numbers you quote (which I think are a bit optimistic), food at least competes with propellant ISRU.

Which would make sense.  A person at rest is a constant 100 Watt consumer I believe.  Factor in the efficiency of metabolism, and the fact that you're not always at rest, and then the efficiency of the agriculture producing the food, and it adds up to near what that BFS needs, per person.
I might be out of context here, but usually when people are comparing fuel ISRU to other energy usage, it is combined with the argument that solar power is sufficient, because even during dust storms you can still have plenty of power for your life support (something like 100w/person), being far less than fuel ISRU. It often comes up in discussions of solar vs nuclear.

Food is a form of energy storage, so the intermittent solar power issues are not such an issue here. You could stockpile basic food calories for a decade ahead. It would be useful if your most basic crops are salvagable if there is a dust storm. I am confident there are such options.

In the longer term I certainly do expect BFR fuel ISRU to become a minor part of the energy budget. It could theoretically become zero when there is enough local population growth.

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 01/21/2018 03:06 pm

So even under the numbers you quote (which I think are a bit optimistic), food at least competes with propellant ISRU.

Which would make sense.  A person at rest is a constant 100 Watt consumer I believe.  Factor in the efficiency of metabolism, and the fact that you're not always at rest, and then the efficiency of the agriculture producing the food, and it adds up to near what that BFS needs, per person.
I might be out of context here, but usually when people are comparing fuel ISRU to other energy usage, it is combined with the argument that solar power is sufficient, because even during dust storms you can still have plenty of power for your life support (something like 100w/person), being far less than fuel ISRU. It often comes up in discussions of solar vs nuclear.

Food is a form of energy storage, so the intermittent solar power issues are not such an issue here. You could stockpile basic food calories for a decade ahead. It would be useful if your most basic crops are salvagable if there is a dust storm. I am confident there are such options.

In the longer term I certainly do expect BFR fuel ISRU to become a minor part of the energy budget. It could theoretically become zero when there is enough local population growth.
What you say is correct in that context. Almost all energy needs are immune to short term variability.

This conversation was in Joules/yr however.

At what point will power for propellant ISRU be overtaken by power for other things like material ISRU, agriculture (which is also ISRU), digging and construction, transportation...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/22/2018 07:17 am
Did we ever create that power-on-Mars thread like we were told to?

[Edit: Quick look. There's a couple of threads (one SpaceX-Mars, on Mission-to-Mars general) which discuss "options for powering", ie, nuke or solar, but I can't see anything that is a general discussion of power demands for various tasks, at various milestones in base/settlement/colony development.]

[Edit2: Jpo234. For example.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 01/22/2018 07:28 am
Did we ever create that power-on-Mars thread like we were told to?

http://forum.nasaspaceflight.com/index.php?topic=39785.0
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/11/2018 12:42 pm
I was sceptical at first, and thought SpaceX would dig their underground Mars base with roadheaders, but given the latest developments with The Boring Company I am coming around to the idea that SpaceX will go for a heavily modified, modular and light TBM for their Mars base construction. For sure using a Tunnel Boring Machine will greatly speed up the pace of tunnelling compared to using a roadheader. Especially if they manage to produce ISRU lining as it seems they are attempting in Los Angeles. 

TBM tunnelling will obviously have a major impact on the lay-out of the underground Mars base since TBMs don't really do sharp corners. I have attached a quick sketch of the style of lay-out we can perhaps expect. Very few sharp corners, lots of curves and straight lines.

It's important to remember that the base could very well work with super-imposed tunnels in several layers.

I imagine that tunnelling will take place at ambient Martian near-vacuum and that sections can then be progressively sealed off. If organised well it would only be necessary to have quite few airlocks.

Dug out material could be used for tunnel lining, berms around the BFS pads, etc.

Thoughts?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/12/2018 09:38 am
[TBM habs]

Even if you are primarily using TBMs, you still need other rock-cutters like road-headers for entries, level changes, etc. TBMs are fussy. So if you have a primarily underground settlement, you don't have to choose only TBM-type tunnels.



However, if I were using TBMs, I'd do parallel tunnels. Say three or four in parallel lines or concentric rings. Enough gap in between for structural stability, but otherwise as close as possible. (Entrances cross-cut between the tunnels. Like the front doors of a street of buildings.) Most of the volume will be agricultural space, then work and living areas. In an early settlement, you might have one tunnel for transport, one for agriculture (hydroponics/aeroponics/aquaculture/livestock), one that's various use, habitat/industrial/etc. As the colony expands, the ag-space invariable gets pushed further away from the main hab areas, and industrial uses move to their own dedicated spaces. And in some busy areas, tunnels are co-opted for extra transport volume.

Multiple parallel tunnels gives you flexible use, and, importantly, changeable usage over time. While, in the very early days, it allows a relatively compact settlement, walking between tunnels from hab to work to ag areas, instead of down long single tunnels. And obviously it provides redundancy, if one tunnel is blocked, you can get around it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 02/12/2018 04:20 pm
Multiple levels of concentric rings. Expanding the habitat rings in three dimensions keeps everything close. (relatively)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/12/2018 09:07 pm
If we go along with the idea that they'll bring a TBM to Mars then I am pretty sure that 99% of the volume of tunnels will be done with the TBM. Making lots of smaller tunnels with a roadheader to connect the bigger TBM tunnels won't make much sense, if you can create connections by cleverly arranging the lay-out of the bigger tunnels.

Making slight inclines a TBM can easily work on various levels. Whether it makes sense I don't know. If the rock space was limited, I guess, but why would they choose a place like that?

I imagine that the drilling crew would spend most of their time in the spaceship and that the whole drilling operation would be highly robotized. Would it make sense to quickly seal the tunnels or would it be better to do all the work in near-vacuum and only seal it up at the end? What do you think?

As for making a seal, I think good old-fashioned bricklaying will be important. Drill crew, bricklayers, electricians... - Not your granddad's astronauts!     
Title: Re: Envisioning Amazing Martian Habitats
Post by: Semmel on 02/12/2018 09:32 pm
wrt. living in tunnels: I think you are missing the point of going to Mars. SpaceX wants to settle Mars because its exciting and fun. There are other reasons but thats the primary there. If you are setting up the settlement as a bunch of tunnels, it defies the purpose. You could live in tunnels here on Earth far cheaper. Settling Mars makes only sense if a significant part of the settlement is above ground. So that you experience Mars on a daily bases. That means windows at the very least.

There is no doubt that tunnels will be a big part of a Mars city. But putting too much emphasis on the tunnels is a mistake I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/12/2018 09:49 pm
Elon mentioned tunnels as factory and workplace. Geodesic domes for habitats. I can not see that yet. Domes are expensive. Tunnels, parallel tunnels with plenty of connections can provide a lot of interesting open space. Geodesic domes will be an important addition. Just to know they are there and one can go there to see plants under natural light and see the outside will be important. But everyday life can be inside IMO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/13/2018 08:12 am
wrt. living in tunnels: I think you are missing the point of going to Mars. SpaceX wants to settle Mars because its exciting and fun. There are other reasons but thats the primary there. If you are setting up the settlement as a bunch of tunnels, it defies the purpose. You could live in tunnels here on Earth far cheaper. Settling Mars makes only sense if a significant part of the settlement is above ground. So that you experience Mars on a daily bases. That means windows at the very least.

There is no doubt that tunnels will be a big part of a Mars city. But putting too much emphasis on the tunnels is a mistake I think.

For the first years it is the "settler" stage. It is about survival and building up a viable colony. The luxuries will come later.

"Experiencing Mars" can be many things. Drilling into bedrock is one way. Hydroponic farming in tunnels is another. Goofing around in low-G is a third way.

Despite primarily living and working in tunnels for the first years our intrepid settlers will have plenty of opportunities to go top-side. I imagine the spaceship will be the primary habitat for a long time. Acres of solar panels will have to be rolled out on the surface as well. Prospecting will also be a big thing, I imagine.

I wonder how much time scientists at Amundsen-Scott South Pole Station spend outside? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Valerij on 02/13/2018 09:37 am
A village-size habitat that is mostly underground, with distributed hydroponic farming based mostly on artificial light and an energy source that is mostly distributed nuclear (https://www.nasa.gov/directorates/spacetech/kilopower (https://www.nasa.gov/directorates/spacetech/kilopower))
Sounds great. However, single Kilopower reactor is only 1 to 10 KWe. How many MWe would be required to lets say, have enough artificial light to reliably feed a dozen people on Mars and also fill up a BFS with ISRU propellant? That seems like a lot of Kilopowers..
...that's why solar is likely to be the predominant power source on Mars.
I do not agree. This means that to ensure the energy of the Martian colony, classical nuclear reactors of high power will be required.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 02/13/2018 12:56 pm
I wonder how much time scientists at Amundsen-Scott South Pole Station spend outside?

A word has been coined for places where being outside is uncomfortable and/or dangerous. The word is "uninhabitable".
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 02/13/2018 04:29 pm
A word has been coined for places where being outside is uncomfortable and/or dangerous. The word is "uninhabitable".

Weeel - no.

In most (all?) inhabited places, most people spend the majority of their time indoors.
In most inhabited places, outside is for portions of the year uncomfortable and/or dangerous to be in for long periods unprotected.

Summer in Vegas, or Arizona, winter in Canada or Scotland.

If protective equipment is convenient enough, it makes going outside pleasant enough that people walk for leisure in climates that would unprotected cause them to at least seek shelter, and perhaps die without it.

Spacesuits are clearly not at the 'unplanned walk outside' stage yet.
Doesn't mean they'll never get there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jim Davis on 02/13/2018 05:20 pm
In most inhabited places, outside is for portions of the year uncomfortable and/or dangerous to be in for long periods unprotected.

And if those portions of the year become almost all of the year the place becomes uninhabited.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 02/13/2018 07:29 pm
In most inhabited places, outside is for portions of the year uncomfortable and/or dangerous to be in for long periods unprotected.

And if those portions of the year become almost all of the year the place becomes uninhabited.


(mod)
You might be in the wrong thread. This thread is about envisioning habitats. Not about debating whether people will or won't go to Mars because it's a rough environment.... for this thread, that's a given, they will... under that assumption, what will their habitats look like.

Please find another thread to debate whether people will go to extreme environments or not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 02/13/2018 08:42 pm
This thread is about envisioning habitats.<snip>
what will their habitats look like.

I wonder about outside being amazing.
(https://upload.wikimedia.org/wikipedia/commons/thumb/9/9b/RyoanJi-Dry_garden.jpg/1024px-RyoanJi-Dry_garden.jpg)

What forms of art might lend themselves to actually being performed on the minimally improved surface?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/09/2018 03:10 pm
there are schemes to shield areas of the surface from radiation using magnetism, but this would require large amounts of energy, i.e. a fairly large nuclear power plant.

Our Omaha Field (http://www.lakematthew.com/press/press-release-november-16-2017/) configuration shields a city-region with < 80 kW.   

It cuts surface dose considerably (green), allowing for short-duration surface habs with little shielding structure, perhaps nothing beyond the pressure vessel itself.  Long-duration habs still require supplemental shielding.

(https://ucarecdn.com/e33745df-7e4e-405d-b270-4a93998b9e77/-/preview/2048x1536/)


Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 03/09/2018 04:01 pm
there are schemes to shield areas of the surface from radiation using magnetism, but this would require large amounts of energy, i.e. a fairly large nuclear power plant.

Our Omaha Field (http://www.lakematthew.com/press/press-release-november-16-2017/) configuration shields a city-region with < 80 kW.   

An interesting paper!
I note on skimming you assume 1W/m or so cooling requirements.
http://www.questthermal.com/products/wrapped-mli claims significantly lower than this, for example.
ReBCO continues to improve.
https://www.alibaba.com/product-detail/2-Generation-High-Temperature-Superconductor-tape_50013334401.html I find it amusing it's now off-the-shelf.

Title: Re: Envisioning Amazing Martian Habitats
Post by: alexterrell on 03/09/2018 04:01 pm
I was sceptical at first, and thought SpaceX would dig their underground Mars base with roadheaders, but given the latest developments with The Boring Company I am coming around to the idea that SpaceX will go for a heavily modified, modular and light TBM for their Mars base construction. For sure using a Tunnel Boring Machine will greatly speed up the pace of tunnelling compared to using a roadheader. Especially if they manage to produce ISRU lining as it seems they are attempting in Los Angeles. 

On Earth, cut and cover is always cheaper than TBMs, where it can be used. A Mars base would probably aim for about 5m of regolith on top of the cut and cover - to roughly match the internal pressure, stop all radiation and provide thermal insulation.

A disadvantage of TBM - especially of the kind the Boring Company is pushing - is the narrow bore. It means too much of your space is taken up with access tunnels, and the inside looks a bit like something of the Aliens set.

With cut and cover, you could dig a 25m wide, 100m long, 12m deep ditch. This would be done with automated diggers and the material would be sent for materials processing to extract useful elements. Then build a 2 story structure, and cover. Then cover with spoil and pressurise. (The structure is strong enough to take the regolith whilst unpressurised).
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/09/2018 05:31 pm
there are schemes to shield areas of the surface from radiation using magnetism, but this would require large amounts of energy, i.e. a fairly large nuclear power plant.

Our Omaha Field (http://www.lakematthew.com/press/press-release-november-16-2017/) configuration shields a city-region with < 80 kW.   

An interesting paper!
I note on skimming you assume 1W/m or so cooling requirements.
http://www.questthermal.com/products/wrapped-mli claims significantly lower than this, for example.
ReBCO continues to improve.
https://www.alibaba.com/product-detail/2-Generation-High-Temperature-Superconductor-tape_50013334401.html I find it amusing it's now off-the-shelf.

Motojima & Yanagi was a unique paper, and it suggested an interesting challenge.  It's always nice to see that someone has worked to accomplish something much harder than what you yourself are considering.

As for cooling requirement, we can note that 1W/m was an Earth requirement.  Extreme martian cold slashes the requirement. 

Quote from: LMT
Terrestrial refrigeration requirement is roughly 1 W/m.  The extremely cold martian environment eases refrigeration requirement (one easy thing on Mars), so the power requirement might be somewhere between 30 and 80 kW.  This is a modest requirement, especially for a facility where some tens of MW must be generated, if only to manufacture sufficient propellant for the crew's Earth-return flights.

Thanks for the WMLI link.  Yes, their methods might lower the Omaha Field power requirement considerably, not that it's very great even now.

(http://www.questthermal.com/sites/default/files/ckfinder/images/Screen%20Shot%202013-11-11%20at%2010_26_23%20AM.png)

And ReBCO tape does continue to improve.  Improvements in critical current density (http://iopscience.iop.org/article/10.1088/0953-2048/29/1/014002) are slashing the mass requirement, which in turn has led us to consider a lightweight cable design modeled after the ENEA-TRATOS design.

(https://ucarecdn.com/6379544a-d7e7-4afc-ac11-4ba5024ff13a/-/preview/2048x1536/)

The advantage of such a lightweight cable is that its self-generated Lorentz forces can self-deploy an Omaha Field (https://launchforth.io/LakeMatthewTeam/artificial-geomagnetic-field-to-protect-a-crewed-mars-facility-from-cosmic-rays/overview/?r=178ed03e-506b-42b5-bae6-c33e61a5ce39#post_12), to enable lightly shielded habs out on a flat plain or at elevated sites.  Lorentz self-deployment would draw cables together above the habs, while lifting those cables to an operational altitude of 1.5 km, or higher.  It's a topic we continue to explore.

(http://www.lakematthew.com/wp-content/uploads/2017/11/InflatableShield.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 03/09/2018 09:06 pm
If the power fails, the cables would fall down, right? Probably bad for any structure underneath (but at least it's not a falling orbital elevator). Can you use Lorentz forces to pull them into position initially, then reinforce them after the fact with supports? Don't need to be supports holding them in exact shape, just such that if power fails they don't fall down totally, if they sag some between supports that's fine until the power is back, I'd assume.

What sort of strain occurs at the outer edges where they are anchored to the ground/structure? Is it trying to pull itself from the structure due to Lorentz forces, or does it act more like a solid dome structure sitting on top of walls, held down by gravity? I'm guessing the cables are in the open Martian atmosphere, not themselves a solid pressurized space, so we don't have to worry about buoyancy ripping them off their moorings, just balancing gravity / mass of the structure and Lorentz forces (and any anti-sag/collapse reinforcements to protect against power loss).
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/09/2018 09:33 pm
If the power fails, the cables would fall down, right?

They're superconductors, so the power cables themselves need no power supply once charged.

The kW power is just for refrigerant replenishment.  If that power system failed, you'd shunt some of the stored power out of the cables into the refrigeration system, as backup.  If that situation persisted for several days, the cables would eventually settle toward the ground, as Lorentz force very slowly decreases.

What sort of strain occurs at the outer edges where they are anchored to the ground/structure? Is it trying to pull itself from the structure due to Lorentz forces, or does it act more like a solid dome structure sitting on top of walls, held down by gravity?

Actually the current would just be calibrated to balance net upward Lorentz force against the weight of primary cable (red), when in operation 1.5 km above the return cable.  With balancing, the primary cable exerts only small horizontal force on the anchor pylon. 

The return cable (purple), would experience downward Lorentz force + weight.  As in our original Omaha Field proposal, light suspension cabling would hold the return cable horizontal.  Anchor pylons would support the suspension cabling.

I'm guessing the cables are in the open Martian atmosphere, not themselves a solid pressurized space, so we don't have to worry about buoyancy ripping them off their moorings, just balancing gravity / mass of the structure and Lorentz forces (and any anti-sag/collapse reinforcements to protect against power loss).

Well, cables would have a tiny vacuum insulation space, but no significant buoyancy, no.  And yes, a balancing of forces and the low cable unit mass should keep the architecture manageable. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/09/2018 11:41 pm
If the power fails, the cables would fall down, right?
They're superconductors, so the power cables themselves need no power supply once charged.

"Power failure" generally means a failure of the active, not the drain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/10/2018 04:28 pm
https://www.alibaba.com/product-detail/2-Generation-High-Temperature-Superconductor-tape_50013334401.html
I find it amusing it's now off-the-shelf.

Test Sites

Off-the-shelf is good.  Superconductor cable tech is generally mature, used daily for example at fusion research centers.  So it may be that a demo of an Omaha Field on Earth, while not trivial, isn't very interesting.  Perhaps the interesting test would be lunar.

Rationale:

Polar craters are candidate sites for a first lunar base.  Shoemaker, for example.  It seems to have a little ice as per the neutron count; maybe enough ice in spots for ISRU experiments like LOX production.

(http://2.bp.blogspot.com/-ahFcMtDxaMM/Ua0SOluTzJI/AAAAAAAAW9I/zRd7bNZEg_c/s1600/SVS-LEND-20130601-580-2.jpg)

A polar network of PV panels can have overlapping illumination to supply power continually, as from the 6 peaks marked on Bussey et al. 2010.

(http://www.lakematthew.com/wp-content/uploads/2018/03/SouthPoleSunlightYearRound_Shoemaker.png)

Shoemaker is in continual shade.  It's deep enough to keep Omaha Field cables in continual shade as well, to minimize refrigeration requirement.  Here a small site of, say, 10 km2, could be protected from cosmic rays by the Omaha Field, and using little power or LOX, all well within capability of even the smallest base infrastructure.

Because most required tech is mature, in some cases off-the-shelf, a system could be designed and constructed in advance of a lunar base initiative, even a rapidly-advancing one.  Deployment would be concurrent with the first temporary residency.  Should the system suffer failure, temporary residents would not incur a great radiation dose, as they return to Earth soon anyway.  Of course you'd want to learn from failures and perfect the system prior to long-term residency.

And no one has to live underground.

Q:  What are the most mature and applicable lunar hardware designs available today?  e.g., designs for lunar LOX plants, suspension-cable systems, and lightweight pylons.  Such designs can extend the initial thought experiment, or factor into some future Mars design.

Refs:

Bussey, D. B. J., McGovern, J. A., Spudis, P. D., Neish, C. D., Noda, H., Ishihara, Y., & Sørensen, S. A. (2010). Illumination conditions of the south pole of the Moon derived using Kaguya topography. Icarus, 208(2), 558-564.

Wright, E. LEND Looks for Water at the South Pole (https://svs.gsfc.nasa.gov/vis/a000000/a004000/a004057/) (2013).  NASA/Goddard Space Flight Center.

--

Addendum on Power and Communication:

A smaller, separate magnetostatic system might serve quite different infrastructure roles in this lunar scenario, providing continuous power and continuous line-of-sight communication with Earth

Solar panels at Connecting Ridge site CR1 in Vanoutryve et al. 2010 (marked up above with red circle in lower left quadrant, and also marked as "B" down below) can have continuous illumination if raised at least 20 m above the surface.  Uninterrupted line-of-sight with Earth would require that the communication platform be raised about 3 km.  Ideally one system would meet both requirements at that site, or at another elevated site analyzed by Vanoutryve et al.

Both requirements might be met with a two-cable magnetostatic system.  Lorentz force draws the two primary cables together and can raise them to 3 km height.  Opposite-facing solar panels could be suspended from the cables to create a pair of PV "walls" for continuous power.  A line-of-sight communication platform would be mounted at apex. 

If the solar panels were designed with reflective backing, they could provide a sunshield to the suspended cables, to cool them and perhaps keep LOX refrigerant requirement manageable.  Room temperature keeps superconductor refrigeration manageable on Earth, so perhaps here as well, if LOX production is robust.

Also, in this system the return cables would be simplified as straight cables, without solenoids, because surface magnetic flux density is not an issue at this uninhabited infrastructure site.

(https://cs9.pikabu.ru/post_img/big/2018/02/19/8/151904726414643948.jpg)

Refs:

Vanoutryve, B., De Rosa, D., Fisackerly, R., Houdou, B., Carpenter, J., Philippe, C., ... & Gardini, B. (2010). An analysis of illumination and communication conditions near lunar south pole based on Kaguya Data. 7th, 10.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 03/12/2018 09:29 pm
That's very interesting, if the failure mode due to loss of power is just a gradual settling, might not do any damage to structures below.

Though I'd still think some kind of basic support would be good in case of some kind of damage that stops the superconducting flow ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/13/2018 12:53 am
That's very interesting, if the failure mode due to loss of power is just a gradual settling, might not do any damage to structures below.

Right.  It's a reversal of deployment. 

One method:  In deployment each primary cable is initially wrapped around a tensioned spool system at the pylons.  As deployment begins superconducting current increases.  Lorentz force exceeds weight and spool tension, so that the primary cable spools out toward operational height.  When you lose power, or just want to lower the cable for maintenance, you decrease superconducting current and Lorentz force, so that tension slowly wraps the cable around the spool again.

Though I'd still think some kind of basic support would be good in case of some kind of damage that stops the superconducting flow ?

To manage superconductor failure, quench protection would be expected, but cable redundancy also protects the system.  For example the ENEA-TRATOS cable design has five independent tape stacks, for five independent currents.  If one tape stack overheats, its current is shunted to the quench protector, and the other four tape stacks continue to operate. 

Result:  Lorentz force decreases by only 1/5, and the cable remains suspended.

--

A loss of all five tape stacks would of course drop the cable.   (And of course you wouldn't place an important structure right on a cable drop path.)

One method to manage:  Increase spool take-up speed to match.  Under lunar gravity a dropped cable would need 43 seconds to fall 1.5 km, so high-speed take-up during fall should be feasible.  When the remaining taut cable reaches pylon top, adjust the spool tension to allow a small play-out that gives a constant deceleration.   When the cable's fall is arrested, lock the spool. 

--

Of course many methods of cable management are conceivable.  What methods might be better?
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 03/13/2018 01:36 am
Of course many methods of cable management are conceivable.  What methods might be better?
Don't insulate the cable stacks from each other?
Or provide shorting bridges very regularly?

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/13/2018 02:59 pm
Of course many methods of cable management are conceivable.  What methods might be better?
Don't insulate the cable stacks from each other?
Or provide shorting bridges very regularly?

Hmm.  Are you thinking of some in-cable quench protection method, perhaps?  But wouldn't the stack contacts also remove redundancy, by spreading hotspots across tape stacks?  Can you expand a bit?  Thanks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 03/13/2018 03:13 pm
Of course many methods of cable management are conceivable.  What methods might be better?
Don't insulate the cable stacks from each other?
Or provide shorting bridges very regularly?

Hmm.  Are you thinking of some in-cable quench protection method, perhaps?  But wouldn't the stack contacts also remove redundancy, by spreading hotspots across tape stacks?  Can you expand a bit?  Thanks.

If your cable is in one enclosure with one thermal environment, heat from a quenched strand is going to be shared across all strands, so if you've got enough heat to make a hotspot spread, then it risks spreading across the whole cable.

If however, the strands are tied together electrically occasionally, what happens instead is as that as one spot quenches, the current is immediately taken up by the other strands, and there is no generated heat, as there is no current flow in the cable that's gone resistive, leading to the possibility that it can become superconducting again if there was some transitory issue.

I need to think about this properly and read the above paper in more depth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/16/2018 08:26 pm
Of course many methods of cable management are conceivable.  What methods might be better?
Don't insulate the cable stacks from each other?
Or provide shorting bridges very regularly?

Hmm.  Are you thinking of some in-cable quench protection method, perhaps?  But wouldn't the stack contacts also remove redundancy, by spreading hotspots across tape stacks?  Can you expand a bit?  Thanks.

If your cable is in one enclosure with one thermal environment, heat from a quenched strand is going to be shared across all strands, so if you've got enough heat to make a hotspot spread, then it risks spreading across the whole cable.

If however, the strands are tied together electrically occasionally, what happens instead is as that as one spot quenches, the current is immediately taken up by the other strands, and there is no generated heat, as there is no current flow in the cable that's gone resistive, leading to the possibility that it can become superconducting again if there was some transitory issue.

I need to think about this properly and read the above paper in more depth.

Cold Steel

I was just thinking you'd want to isolate the hotspot within the originating tape stack, for safety.  The selection of cable core material could do that.  For example, looking at that ENEA-TRATOS design, if you replace their aluminum core with austenitic stainless steel, you get a core having much lower thermal conductivity than the tape stacks.  Result:  the core is a relative thermal insulator, isolating a hotspot within its originating tape stack.

--

And yes, the quench protector would quickly remove current and prevent further heating in the warmed tape stack.  However if the cause of the hotspot were not obviously an eddy current transient, I think you'd want to lower the cable for inspection before firing up that specific circuit again.  If a physical defect were the cause, it would likely be located within that one tape stack.

--

Incidentally, stainless steel also has exceptional and maximized fracture toughness at those cryogenic temperatures.  Implication:  stainless steel enables safe use of high cable tension, as for example in the (hopefully very unlikely) emergency of free-fall cable arrest.

Refs:

Bonura, M., & Senatore, C. (2015). Transverse thermal conductivity of REBCO coated conductors. (https://arxiv.org/ftp/arxiv/papers/1412/1412.1335.pdf) IEEE Transactions on Applied Superconductivity, 25(3), 1-4.

Duthil, P. (2015). Material properties at low temperature. (https://arxiv.org/ftp/arxiv/papers/1501/1501.07100.pdf) arXiv preprint arXiv:1501.07100.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 07/04/2018 08:03 am
Top 10 Teams Selected in Virtual Model Stage of NASA’s 3D-Printed Habitat Challenge (https://www.nasa.gov/directorates/spacetech/centennial_challenges/3DPHab/top-10-virtual-model-stage)
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 09/01/2018 12:26 pm
https://amp.space.com/39760-mars-ice-home-concept-in-pictures.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 09/03/2018 07:53 am
One of my hobby horses is that although terraforming is hard, oceanforming is easy. All over the solarsystem there are icy worlds (and mars has ice caps 4km thick) and if we buried ourselves in them our waste heat would trivially begin building ocean environments with all the basics for life: pressure, temperature between freezing and boiling, radiation protection.

(Some worlds already have oceans of course but the point is it is not important. Our waste heat will create them anyway. There is no cost, in fact a way of disposing arbitrary amounts of waste heat is a convenience)

If we mastered self sufficient lifestyles under water on earth then these might translate easily to the rest of the solar system.

Im not sure if this clip is the most relevant, but it is very pretty.

https://youtu.be/VwawntVZYEg

(edit: wrong clip)
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 09/06/2018 11:16 pm
I was just wondering if anyone has a good handle on the lapse rate of the atmosphere and the temperature profile of the upper crust on Mars.

The reason is that evacuated caverns deep down may be doable if the temperature and atmospheric pressure provide any advantage to using such caverns in which to construct facilities. Reaching ~5psi pressure would be a significant benefit allowing survival with only an oxygen mask for breathing.

Another way of asking the question above is, "What would the atmospheric pressure at the bottom of a 30 km deep shaft on Mars?" And what would the rock temperature be at the bottom of a 30 km deep shaft on Mars?" Then substitute your best guess at a practical depth and use that instead of 30 km in these questions. I have used "shaft" as in "elevator shaft" which could be used for both surface access and cooling atmosphere flow.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 09/06/2018 11:27 pm
I did a search and found this calculation by RobotBeat:

Excavating a portion of Hellas Planitia deep enough that the surface pressure is above the Armstrong Limit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 09/07/2018 01:24 am
I did a search and found this calculation by RobotBeat:

Excavating a portion of Hellas Planitia deep enough that the surface pressure is above the Armstrong Limit.

https://forum.nasaspaceflight.com/index.php?topic=22046.msg608359#msg608359 (https://forum.nasaspaceflight.com/index.php?topic=22046.msg608359#msg608359)

That was an interesting read, evacuating an open pit but the idea here is an elevator shaft down to depth. Atmospheric pressure would increase down a shaft just the same as down an open pit. Robobeat calculates about 18 km deep below Hellas basin to get enough pressure but doesn't consider the natural temperature of the rock at that depth. On Earth, rock temperature goes up quickly with depth and I don't think Mars is totally dead. I don't know what the temperature gradient is though.

A shaft would be easier to dig, easier to seal against collapse and equally useful to transfer human-generated heat from the facility at the bottom. It all depends on what the actual rock temperature is at depth. And of course, the lack of something much better being developed before digging such a shaft becomes doable in the future. It seems to me that something better should come along.

Edit Add:
KelvinZero's idea, posted elsewhere, of just filling the elevator shaft with water would be easier. Just make the shaft a little oversized then convert the elevator car to a bathysphere with watertight seals around the lower exit door. That is, the lower exit would be a water lock, like an airlock only working underwater instead of in a vacuum. This system would hold atmospheric pressure as long as the cavern with facilities at the bottom was deep enough so that the overburden could prevent a blowout.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 09/07/2018 02:25 pm
Robobeat calculates about 18 km deep below Hellas basin to get enough pressure but doesn't consider the natural temperature of the rock at that depth. On Earth, rock temperature goes up quickly with depth and I don't think Mars is totally dead. I don't know what the temperature gradient is though.

The googles says 8℃/km. So ~140-150℃ above surface temp at Hellas. Not good.

But if you're able to afford to dig a great big, multi-km deep hole. Sealing a fail-safe roof across a much shallower shaft seems pretty basic.

KelvinZero's idea, posted elsewhere, of just filling the elevator shaft with water would be easier.

Given that ~26m of water gives one atm of downward pressure, it's not only easier, it's not even in the same league as digging a multi-km shaft.



As an aside, the vapour pressure from water alone is almost the same as Mars' atmospheric pressure. Ie, at that pressure of water-vapour, boil-off stops. Note: Of water vapour. Doesn't help you outside, since it's a partial-pressure thing. However, if you merely stop the exchange of water-vapour and Mars air, by having an unpressurised door, you won't lose water from the water-lock once it hits vapour pressure. Hence ideally, the water temperature would be kept at the level needed to reduce the vapour pressure to ambient Mars air pressure. But in most places, that's around or just below freezing. (610pa at 0℃, 870pa at 5℃) So in practice, you'd want a low-pressure capable door. Say max difference 1 kpa. I assume you'd also have both an outer and inner door each capable of maintaining a full 1atm difference, as backup for failure elsewhere. But the water-lock lets you keep the inner-hatch open, and the water-vapour atmosphere in a low-pressure outer room lets you keep the outer hatch open. You only need a low-pressure door.

Assuming you aren't struggling for every drop of water (or you wouldn't have considered a water-lock), then you don't need to worry about losing a little water-vapour when you open the low-pressure door. Similarly, you don't need to pump it down into an air-tank, you just vent the door before opening. Depending on how fast the boil-off is from the water-lock when at ambient Mars pressure, you might even be able to leave the door unpressurised during the multi-hours long EVA. Just close it to stop the free exchange of water-vapour and Mars air, but leave the vents open.

If that low-pressure door fails, the only danger is the faster boil-off of water in the water-lock. Long, long time to repair it, to close the outer emergency hatch, or to close the inner hatch.

convert the elevator car to a bathysphere

Hardly a "bathysphere". By definition, the highest desirable pressure difference is 1atm.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 09/07/2018 04:46 pm
I remember some older concepts that used certian oils that remain liquid at mars surface pressure for vapor locks. Is that a better option that water?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 09/07/2018 05:01 pm
If you have a robust ISRU infrastructure including complex hydrocarbon synthesis, yes... otherwise you have to import all the oil so no (presumably)
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 09/07/2018 05:23 pm
Maybe just float a small amount of oil on top of the water to stop it evaporating.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 10/21/2018 02:12 pm

(snip)

As an aside, the vapour pressure from water alone is almost the same as Mars' atmospheric pressure. Ie, at that pressure of water-vapour, boil-off stops. Note: Of water vapour. Doesn't help you outside, since it's a partial-pressure thing. However, if you merely stop the exchange of water-vapour and Mars air, by having an unpressurised door, you won't lose water from the water-lock once it hits vapour pressure. Hence ideally, the water temperature would be kept at the level needed to reduce the vapour pressure to ambient Mars air pressure. But in most places, that's around or just below freezing. (610pa at 0℃, 870pa at 5℃) So in practice, you'd want a low-pressure capable door. Say max difference 1 kpa. I assume you'd also have both an outer and inner door each capable of maintaining a full 1atm difference, as backup for failure elsewhere. But the water-lock lets you keep the inner-hatch open, and the water-vapour atmosphere in a low-pressure outer room lets you keep the outer hatch open. You only need a low-pressure door.

Assuming you aren't struggling for every drop of water (or you wouldn't have considered a water-lock), then you don't need to worry about losing a little water-vapour when you open the low-pressure door.

(snip) (emphasis added)


Great points. Our "Redwood Forest" design for a city on Mars was designed as a water-rich city, so we deliberately came up with ways to use and store water everywhere: radiation shielding, vast cisterns for swimming and for storage, hydroponics, personal vegetable patches, underground canals connecting the domes, and swim-through water-locks leading from the lowest levels up 26m to the outdoors. For the water-locks we used a low-pressure surface antechamber with revolving doors and mechanical air handling systems to keep the water liquid and dynamically stable. As you point out, in our design we don't care about losses of vapor to the outside when people use the water-lock because the key principle is that the city will be water-rich.
Title: Re: Envisioning Amazing Martian Habitats
Post by: moreno7798 on 11/05/2018 09:41 pm
Wondering if SpaceX is going to try to implement Kimbal Musk's farming technology on Mars . . .

https://youtu.be/VxRNoSSkLkE
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 11/25/2018 04:47 pm
Saw this on r/CozyPlaces (https://www.reddit.com/r/CozyPlaces/comments/9zja9i/cozy_desert_view/). Something like this on Mars would be amazing...
It's probably from Amangiri (https://www.aman.com/resorts/amangiri)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/25/2018 10:06 pm
Something like this on Mars would be amazing...

You might want to close that window/door.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 11/27/2018 01:42 am
Something like this on Mars would be amazing...

You might want to close that window/door.

The blinds will only be closed during dust storms.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 11/27/2018 04:22 am
Something like this on Mars would be amazing...

You might want to close that window/door.
Put a transparent fishtank there for rad shielding/aquaponics.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 11/27/2018 12:14 pm
Something like this on Mars would be amazing...

You might want to close that window/door.
Put a transparent fishtank there for rad shielding/aquaponics.

Sitting in a comfy chair looking out, you'd only get cosmic radiation coming in through a 90 degree x 45 degree solid angle, approximately 1/32 of what you would get sitting out in space. Of that, it's halved again by the horizon, and then more chunks are taken out of it by terrain features. That cosmic radiation is also coming in at a steep angle through the atmosphere, through an average atmospheric slope thickness of 22.5 degrees.

You'd get some backscatter, but it would be fairly small I think. A thick piece of acrylic would cut that down, and of course water would be great too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/27/2018 12:21 pm
Something like this on Mars would be amazing...

You might want to close that window/door.
Put a transparent fishtank there for rad shielding/aquaponics.

Sitting in a comfy chair looking out, you'd only get cosmic radiation coming in through a 90 degree x 45 degree solid angle, approximately 1/32 of what you would get sitting out in space. Of that, it's halved again by the horizon, and then more chunks are taken out of it by terrain features. That cosmic radiation is also coming in at a steep angle through the atmosphere, through an average atmospheric slope thickness of 22.5 degrees.

You'd get some backscatter, but it would be fairly small I think. A thick piece of acrylic would cut that down, and of course water would be great too.

At that angle, the atmosphere is equivalent to about 3 m of water. Would need a pretty big fish tank to appreciably improve that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 11/27/2018 01:45 pm
Something like this on Mars would be amazing...

You might want to close that window/door.
Put a transparent fishtank there for rad shielding/aquaponics.

Sitting in a comfy chair looking out, you'd only get cosmic radiation coming in through a 90 degree x 45 degree solid angle, approximately 1/32 of what you would get sitting out in space. Of that, it's halved again by the horizon, and then more chunks are taken out of it by terrain features. That cosmic radiation is also coming in at a steep angle through the atmosphere, through an average atmospheric slope thickness of 22.5 degrees.

You'd get some backscatter, but it would be fairly small I think. A thick piece of acrylic would cut that down, and of course water would be great too.

At that angle, the atmosphere is equivalent to about 3 m of water. Would need a pretty big fish tank to appreciably improve that.

Think you misplaced a decimal point, Mars' atmospheric column is 20g/cm^2 and at 22.5 degrees that's about 50g/cm^2.

With properly designed buildings (which colonists spend most of their time in) you could build domes* with less transparent radiation shielding. And I firmly believe that Musk is going to offer domes of some sort. The front of Starship is already half a dome. Nobody wants to go to Mars to live in a cave and peek out through an airlock portal the engineers grudgingly allowed.

Water features with a thin layer of oil would be an interesting sight.

*half-buried pressure vessels
Title: Re: Envisioning Amazing Martian Habitats
Post by: envy887 on 11/27/2018 02:09 pm
Something like this on Mars would be amazing...

You might want to close that window/door.
Put a transparent fishtank there for rad shielding/aquaponics.

Sitting in a comfy chair looking out, you'd only get cosmic radiation coming in through a 90 degree x 45 degree solid angle, approximately 1/32 of what you would get sitting out in space. Of that, it's halved again by the horizon, and then more chunks are taken out of it by terrain features. That cosmic radiation is also coming in at a steep angle through the atmosphere, through an average atmospheric slope thickness of 22.5 degrees.

You'd get some backscatter, but it would be fairly small I think. A thick piece of acrylic would cut that down, and of course water would be great too.

At that angle, the atmosphere is equivalent to about 3 m of water. Would need a pretty big fish tank to appreciably improve that.

Think you misplaced a decimal point, Mars' atmospheric column is 20g/cm^2 and at 22.5 degrees that's about 50g/cm^2.

With properly designed buildings (which colonists spend most of their time in) you could build domes* with less transparent radiation shielding. And I firmly believe that Musk is going to offer domes of some sort. The front of Starship is already half a dome. Nobody wants to go to Mars to live in a cave and peek out through an airlock portal the engineers grudgingly allowed.

Water features with a thin layer of oil would be an interesting sight.

*half-buried pressure vessels

20 g/cm2 atmospheric column at datum, but colonies are likely to be well below datum. Either way, I shouldn't do trig in my head :D the best case at 22.5 deg oblique angle at the bottom of Hellas is about 1 meter water equivalent and not 3 m. At datum it's about half a meter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 11/29/2018 11:53 am

JPL / Blackbird Interactive's* little interactive Mars base demo is available on Steam.  There's not a lot to do other than look around.  The scanner model lets you mouse over buildings for descriptions.

https://store.steampowered.com/app/224000/Project_Eagle_A_3D_Interactive_Mars_Base/



* Homeworld developers, for those who like games.  It would be nice if they did develop this into a full game.  Neither of the recent-ish Mars strategy games have struck a chord with me.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 11/29/2018 12:00 pm
Something like this on Mars would be amazing...

You might want to close that window/door.
As long as you only sit in front of the window an hour a day, you should be OK?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 11/29/2018 09:00 pm
Something like this on Mars would be amazing...

You might want to close that window/door.
As long as you only sit in front of the window an hour a day, you should be OK?

Recall the inside of the F-16 glass canopy is coated with a thin layer of gold. Will some similar technique significantly reduces the radiation exposure dosage?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/30/2018 08:57 am
Something like this on Mars would be amazing...
You might want to close that window/door.
As long as you only sit in front of the window an hour a day, you should be OK?
Recall the inside of the F-16 glass canopy is coated with a thin layer of gold. Will some similar technique significantly reduces the radiation exposure dosage?

In case you missed the joke, there's no glass on that opening (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1880198#msg1880198).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 11/30/2018 11:55 pm
Something like this on Mars would be amazing...
You might want to close that window/door.
As long as you only sit in front of the window an hour a day, you should be OK?
Recall the inside of the F-16 glass canopy is coated with a thin layer of gold. Will some similar technique significantly reduces the radiation exposure dosage?

In case you missed the joke, there's no glass on that opening (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1880198#msg1880198).

Didn't missed the joke. It is just strange to see an open space that big without a glass panel.

But the query remains can a gold plated glass panel reduce radiation exposure on the Martian surface.


Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/01/2018 12:07 am
A thin, transparent  layer, like on helmets? Only from alpha (helium nuclei) and low energy beta (electrons). Higher  energy beta hitting gold will create x-rays via bremstrahlung, and hard x-rays will pass through a transparent coating- or worse, scatter. 

Lead or barium/lead  glass is better, and ALON may be acceptable for mild environments (impact resistant too).
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/01/2018 12:08 am
But the query remains can a gold plated glass panel reduce radiation exposure on the Martian surface.
Just answering as a layman.. I would say absolutely not. You generally want a meter or so of material with a high hydrogen content such as water or various plastics to make any difference.

(edit) To clarify, in space a few grams per square centimetre DO make a useful difference. I think this can eliminate the low energy radiation that there is a lot of.. but once you have gotten rid of the easy stuff you are left with high energy cosmic rays and similar and that stuff gets really hard to block. You can't just say a few grams blocks half the radiation so a few more grams will halve it again, and so on.


Maybe for a vertical window you could get significant gains from much less since most of the radiation is probably coming from above rather than from near the horizon. Also it is probably the shielding above your head that matters most. That is one of the reasons I like the idea of towers instead of domes.

Anyone know what this gold film is for? Maybe it is for shielding against something else, like ultraviolet or glare in general?

(google is your friend.. just found this: )
https://aviation.stackexchange.com/questions/29107/why-does-the-canopy-of-the-f-22-raptor-have-a-golden-tinge

https://aviation.stackexchange.com/questions/21802/what-kind-of-materials-is-being-used-for-fighter-jets-glass-shields

The "radiation" it is keeping out is things like microwaves and also scatters radar according to those links.. not cancer causing radiation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 12/01/2018 11:19 am
About GCR coming through the window. It is probably not that bad. The vertical component is still shielded by the roof material. What comes in is going at a low angle through a lot of atmosphere. The total coming in is a small part of the total dose you would get in a space suit outside. You still would not want your bed or desk right by the window.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/01/2018 11:42 am
........Which is why SpaceX is heading underground: the radiation issue is solved.

Also: when you go underground you don't make structures, you make spaces. The structures are already there. In abundance. They're called bedrock.

Sure, living underground can be a bit oppressive. However, it won't be the first time humanity starts settling a planet by living in caves.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/01/2018 01:01 pm
........Which is why SpaceX is heading underground: the radiation issue is solved.
>
Sure, living underground can be a bit oppressive. However, it won't be the first time humanity starts settling a planet by living in caves.

We're already becoming Morlocks, at least in terms of our habitation.

The EPA reports the average US resident spends 87% of their life indoors and 6% in vehicles. That's just 7% of our time outdoors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 12/01/2018 07:39 pm
........Which is why SpaceX is heading underground: the radiation issue is solved.
>
Sure, living underground can be a bit oppressive. However, it won't be the first time humanity starts settling a planet by living in caves.

We're already becoming Morlocks, at least in terms of our habitation.

The EPA reports the average US resident spends 87% of their life indoors and 6% in vehicles. That's just 7% of our time outdoors.

Are you aware on if this is broken down into purposeful and unpurposeful outdoors?

I.E - you can't really count people who walk to work as it's the only option they have, if they would by choice use a car.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/01/2018 09:16 pm
The statistic is very interesting as it is and I really can't see the point of - or possibility of - finding out whether the time spent outside is involuntary or not.

Made me wonder what the percentage of time spent outside is for me. Probably much less than it should be!
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/01/2018 10:21 pm
........Which is why SpaceX is heading underground: the radiation issue is solved.
>
Sure, living underground can be a bit oppressive. However, it won't be the first time humanity starts settling a planet by living in caves.

We're already becoming Morlocks, at least in terms of our habitation.

The EPA reports the average US resident spends 87% of their life indoors and 6% in vehicles. That's just 7% of our time outdoors.

Are you aware on if this is broken down into purposeful and unpurposeful outdoors?

I.E - you can't really count people who walk to work as it's the only option they have, if they would by choice use a car.

That should be a rather small subset. The vast majority of commuters, school or work, are driven, use mass transit or school buses.

Also, that data is at least a decade old. I seriously doubt it's improved, most likely  the opposite.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 12/01/2018 11:47 pm
(snip)

Maybe for a vertical window you could get significant gains from much less since most of the radiation is probably coming from above rather than from near the horizon. Also it is probably the shielding above your head that matters most. That is one of the reasons I like the idea of towers instead of domes.

(snip)


and

About GCR coming through the window. It is probably not that bad. The vertical component is still shielded by the roof material. What comes in is going at a low angle through a lot of atmosphere. The total coming in is a small part of the total dose you would get in a space suit outside. You still would not want your bed or desk right by the window.

In the old days, before air conditioning, vernacular (i.e. traditional) architecture in tropical latitudes often included  overhanging roofs to keep the sun's heat out in the summer and soak it in during wintertime.

Water-rich cities on Mars would probably have large quantities of "structural water" anyway, which would double as an emergency reserve. So, a "Mars vernacular" architecture might include cylindrical high-rise towers with overhanging water tanks between floors, like this:
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/02/2018 12:17 am
If radiation from the side was still a problem, you could probably also use a periscope technique. I have seen this with a single level in some moon-base designs, but with a tower, every level could use the same trick, showing you instead a view from the level below.

You could probably also use the periscope to zigzag light left and right around vertical pillars that are better for supporting the tower, though I suspect horizontal periscopes would give a more panoramic view.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/02/2018 12:41 am
If radiation from the side was still a problem, you could probably also use a periscope technique. I have seen this with a single level in some moon-base designs, but with a tower, every level could use the same trick, showing you instead a view from the level below.

You could probably also use the periscope to zigzag light left and right around vertical pillars that are better for supporting the tower, though I suspect horizontal periscopes would give a more panoramic view.
Radiation from the side isn't much of a problem because the effective amount of atmosphere the radiation would have to travel through is FAR greater. Near the horizon, there's very low dose. Might be equivalent to high altitude on Earth.

There is some scattering that occurs as well, but that bites both ways and generally speaking the does from sky near the horizon is miniscule. So you could be surrounded by a 360 degree vista of Mars and have basically no radiation if your roof is very well-shielded.

It might be really cool to build on a mountain in Mellas Chasma for this reason. Jaw-dropping visuals, low dose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/02/2018 03:06 am
If you hollowed out mesa's, like the " Acheron Fin " in KSR's Mars trilogy and had windows set back 2 metres or so then that should provide enough natural rock overhang.  Same as the apartments looking into the caldera of Pavonis Mons.  If on the north and/or south face then direct solar radiation should be very limited.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/02/2018 03:58 am
If radiation from the side was still a problem, you could probably also use a periscope technique. I have seen this with a single level in some moon-base designs,
>

Or stick a 4k camera on the roof, fed to an AUX input of a wall size LED/QD display.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/02/2018 04:33 am
Or stick a 4k camera on the roof, fed to an AUX input of a wall size LED/QD display.
And if you are going to do that why just show the outside when you can have.. dinosaurs! :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 12/02/2018 10:14 am
Or stick a 4k camera on the roof, fed to an AUX input of a wall size LED/QD display.
And if you are going to do that why just show the outside when you can have.. dinosaurs! :)

I got heavily downvoted on reddit when I voiced the opinion that a HD TV screen is not a full replacement for real windows. There must be a generation out there who do not appreciate that difference.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 12/02/2018 10:59 am
All this talk of radiation shields above the windows makes me think of a famous building that has similar sun shields. It even has solar panels and a large airlock! I'll leave it to others to argue about doming over the courtyard ;D
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/02/2018 11:01 am
Or stick a 4k camera on the roof, fed to an AUX input of a wall size LED/QD display.
And if you are going to do that why just show the outside when you can have.. dinosaurs! :)

I got heavily downvoted on reddit when I voiced the opinion that a HD TV screen is not a full replacement for real windows. There must be a generation out there who do not appreciate that difference.
I wouldn't have thought so either. Good enough for some purposes no doubt. The easiest scenery would be where everything is at infinite range so there is no 3d or depth of field to worry about. I guess you would still need some panoramic trick so that (if you don't have real 3d) the background appears at infinite distance, and you get totally different views when you press your face against the glass and look left and right.

Even within those limitations I would love to see something like that. Imagine space views where you are only a few thousand miles from Saturn or something like that. Scenes from that Wanderers short film done in 360° and viewed though screens on different walls, all in sync. Thats what I imagine we might be able to get pretty close to at the moment, with some sort of clever optics.

If this was easy I would have thought it would be something we saw every day in malls though. If we could do it with 4k screens surely it would be far easier with photographic stills.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 12/03/2018 08:58 pm
........Which is why SpaceX is heading underground: the radiation issue is solved.
>
Sure, living underground can be a bit oppressive. However, it won't be the first time humanity starts settling a planet by living in caves.

We're already becoming Morlocks, at least in terms of our habitation.

The EPA reports the average US resident spends 87% of their life indoors and 6% in vehicles. That's just 7% of our time outdoors.

Are you aware on if this is broken down into purposeful and unpurposeful outdoors?

I.E - you can't really count people who walk to work as it's the only option they have, if they would by choice use a car.

That should be a rather small subset. The vast majority of commuters, school or work, are driven, use mass transit or school buses.

Also, that data is at least a decade old. I seriously doubt it's improved, most likely  the opposite.
That particular involuntary reason to be outside perhaps has decreased.

If you are trying to ask 'how much time do people need to be outside for their mental health' - then counting times people are disinterested in their surroundings, or are actively wishing they could be inside contaminates your data.

At least for me, a very substantial fraction of time outside is done on tasks I do not enjoy, and would prefer someone else did, and I would not be outside if that happened.
Everything from hedge-trimming the awkward parts, clearing snow, securing things before high winds, most weeding, car maintenance (much rather be in garage), ... 

Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/04/2018 05:46 am
And I've been the opposite, camping for several weeks at a time -  sometimes in winter, always remote.

People like me should probably be assigned to resource scouting, transporting between bases etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 12/04/2018 01:18 pm
Any discussion of the necessity of being outside needs to account for how "outside" one feels in an environmental suit.  Sure, you get the sun (through the faceplate) and the soil (through your insulated soles and gloves), but I'm not sure how "outside" it would feel.  And, of course, Mars outside is pretty austere in any case.

It may be more beneficial for mental health to have substantial greenhouse spaces that people can visit, with plants they can touch, water they can feel and hear, and scents they can smell.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/04/2018 11:55 pm
Any discussion of the necessity of being outside needs to account for how "outside" one feels in an environmental suit.  Sure, you get the sun (through the faceplate) and the soil (through your insulated soles and gloves), but I'm not sure how "outside" it would feel.  And, of course, Mars outside is pretty austere in any case.

It may be more beneficial for mental health to have substantial greenhouse spaces that people can visit, with plants they can touch, water they can feel and hear, and scents they can smell.
Also there actually has to be a fair bit of greenery per person. A sustainable base cannot be people living in cramped tin cans. (If we did things we did it on earth, each person would have their own acre of land for farming and biosphere etc )

I see trips outside as between tramping and mountain climbing expeditions.. the type with oxygen bottles.. not something you do to stretch your legs after dinner.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/05/2018 07:14 am
Any discussion of the necessity of being outside needs to account for how "outside" one feels in an environmental suit.  Sure, you get the sun (through the faceplate) and the soil (through your insulated soles and gloves), but I'm not sure how "outside" it would feel.

According to astronauts who've done space-walks, you feel pretty genuinely "out there", even though you're in what is effectively a mini-spaceship and are merely looking out a window.

It may be more beneficial for mental health to have substantial greenhouse spaces that people can visit, with plants they can touch, water they can feel and hear, and scents they can smell.

The problem is, as has been debated endlessly in a few of the Mars threads, a proper "greenhouse" (a transparent one under sunlight) adds complexity that a conventional large module doesn't. It occurs to me that you might have a small place, equivalent of the ISS cupola, scaled to the size/population of the habitat, that is all windows, purely for looking out onto the Martian surface. But not the large agricultural spaces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 12/05/2018 07:58 am
Quote
According to astronauts who've done space-walks, you feel pretty genuinely "out there", even though you're in what is effectively a mini-spaceship and are merely looking out a window.

In fairness, space-walks are comparatively a one off scenario.  I imagine that the day to day grind of prepping for outside activities might pose a reminder for some of their confines.  But, people who might have issues like this hopefully are vetted out prior to committing to Mars to begin with.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/05/2018 09:20 am
And I've been the opposite, camping for several weeks at a time -  sometimes in winter, always remote.

People like me should probably be assigned to resource scouting, transporting between bases etc.

I'm with you, Doc.  I quite enjoy my own company and could happily live in / out of a 2 man rover
for weeks at a time just coming in to drop off samples and take on supplies.

'Doin A Watney' might be pushing the bounds a bit, though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 12/05/2018 01:30 pm
a proper "greenhouse" (a transparent one under sunlight) adds complexity that a conventional large module doesn't. It occurs to me that you might have a small place, equivalent of the ISS cupola, scaled to the size/population of the habitat, that is all windows, purely for looking out onto the Martian surface. But not the large agricultural spaces.
I suppose "greenhouse" isn't the correct term for what I was thinking, as I don't think having a transparent roof matters nearly as much as having a lot of green plants one can sit in/walk through/be around.  I'm envisioning a large open space with plants, lots of light, warm humid air, and perhaps the sound of water.  Whether the space is above ground or under, and that light is provided by the sun through transparent panels or by artificial lights in a cave, I think are less important psychologically.

In other words, hanging out in a conservatory matters more than seeing/walking in a desert (especially while wearing a pressurized suit).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/05/2018 01:59 pm
........Which is why SpaceX is heading underground: the radiation issue is solved.

Also: when you go underground you don't make structures, you make spaces. The structures are already there. In abundance. They're called bedrock.

Sure, living underground can be a bit oppressive. However, it won't be the first time humanity starts settling a planet by living in caves.

As someone who spends their time looking at fractured borehole wall rock, I can tell you that it is not the panacea people think it is. Studies of lunar and Martian base construction mention it, then toss it aside because of the problems.

You have to physically cut (heavy equipment) and remove it (heavy equipment), whilst keeping the support structure intact through pillars or rockbolts and shotcrete, and even then it crumbles and collapses. Earthmoving equipment depends on its weight for purchase. On Mars, these things are reduced. Your tunnel boring machine could start turning on its own axis if it's not securely anchored.

Typical depths to competent bedrock on Earth are on the order of 20-30m. On Mars, it's a complete unknown.

If for some reason you are in a section that is cut off in an emergency, someone has to actively tunnel to get to you. A structural failure would mean tonnes of rock collapsing on you. If you are digging the tunnel, you can lose your tunnelling machine to structural failure. Or worse, you could discover that competent bedrock is absolutely nonexistent down to 50m.

Assuming you overcome all these challenges, and seal the tunnels with sintered concrete / vitrification, build in escape stairways, you then discover that because you have landed in an area with permafrost for propellant and water, the waste heat from your underground habs has started to melt it...

*"You" being the hypothetical Martian settlers

Now there are ways to build underground on Mars, but hiring The Boring Company is not going to be the solution. Lava tubes are there, vitrified and easy to seal. Cutting into a mesa like in Red Mars which was mentioned upthread is another valid idea, although subject to the questions of rock competency I would ask.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 12/05/2018 06:16 pm
According to astronauts who've done space-walks, you feel pretty genuinely "out there", even though you're in what is effectively a mini-spaceship and are merely looking out a window.

When I go outside I don't really feel like I'm "out there" until I put my glasses on. Without those two "windows" everything looks fuzzy.

Think of an EVA suit as heavy clothing and a helmet, just like what you should wear riding a motorcycle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/06/2018 01:49 am
Which is why SpaceX is heading underground: the radiation issue is solved. Also: when you go underground you don't make structures, you make spaces. The structures are already there. In abundance. They're called bedrock.

Bedrock isn't required. The requirements for radiation, even assuming the worst numbers and the least tolerance for risk, require only a few metres of regolith.

Just as you can pile rubble over your surface modules, you can cut down and cover with lose material. Or, just as you can sinter regolith blocks for external structural elements and just add the internal pressure liner, you can cut and sinter a buried structure into which you add the pressure vessels proper.

(To answer the obvious question: if you can cover surface modules, why add the hassle of also excavating down? You have to dig up the regolith to cover the habs. So use the hole you dug. For any given volume of covering, putting the module in the hole reduces the amount you need to dig. Although you might end up with a sort of half-buried, half-covered structure. But I'm not a purist. Whatever works, works.)

You don't need bedrock. Indeed, you might actively avoid it until your capabilities have improved. And even then, only dig into bedrock because the size of the structures exceeds the depth of the regolith.

(The exception will be if you have to dig water out of buried aquifers. Then you have to know how to dig down, how to support your work areas, and since you have that excavated volume available...)

[edit: split out the other part of my reply into a separate post]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/06/2018 01:50 am
Earthmoving equipment depends on its weight for purchase. On Mars, these things are reduced.

As I understand it, some diggers (like TBMs) don't rely on weight, but push against their previous anchor points. I suspect something similar will need to be done for all earthmoving equipment. Deployable anchors that dig in behind any vehicle when it needs to push forward.

This would be required for all surface work, even just a grader, so it's a general problem, not just for underground work.

you then discover that because you have landed in an area with permafrost for propellant and water, the waste heat from your underground habs has started to melt it...

To be fair, you aren't going to "discover" this after-the-fact. Civil engineering isn't new. Assaying rock, making stable underground structures, understanding water movement, etc, is all stuff we do already. The maths needs to get tweaked for Mars (less gravity, pressure difference), but the basis for the maths is the same.

Cutting into a mesa like in Red Mars which was mentioned upthread is another valid idea, although subject to the questions of rock competency I would ask.

Cutting into a mesa is cutting into bedrock.

Lava tubes are there, vitrified and easy to seal.

The latter is debatable. We don't know how structurally sound any tube would be, how permeable/airtight, how clear. We'd have to do the same engineering analysis as with any underground work. (The advantage is that it is, nonetheless, pre-dug.)

As I've mentioned many times, my favourite part of lava tubes is that anything underground will have a temperature that is the average of the surface temperature (heat-pulses mush together the deeper you go). For most places on Mars, even at the equator, lava tubes would be below freezing. Hence water vapour that heats up on the surface will freeze out in the tubes. I suspect that a short way inside from any skylight or breach will be a solid plug of water ice. (Maybe CO₂ as well, depending on the temp.)

Radiation shielding, huge excavated volumes, water in a nice solid filtered form. What's not to love.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JasonAW3 on 12/06/2018 02:00 am
A thin, transparent  layer, like on helmets? Only from alpha (helium nuclei) and low energy beta (electrons). Higher  energy beta hitting gold will create x-rays via bremstrahlung, and hard x-rays will pass through a transparent coating- or worse, scatter. 

Lead or barium/lead  glass is better, and ALON may be acceptable for mild environments (impact resistant too).

Eh, I still like the aquaponics window idea...

      The image of exotic, or even food fish swimming against a Martian horizon and landscape gives me a bit of a kick!
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/06/2018 10:40 am
Personally, I think both would/should be included. Different people will have different ideas of what "Open Space" means.  A couple of 2 or 3 metre diameter dome shaped structures with 6 or 8 windows around the circumference would provide ample viewing of the outside while a large room full of plants, an indoor garden, will also have a therapeutic effect at other times.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/06/2018 03:15 pm
........Which is why SpaceX is heading underground: the radiation issue is solved.

Also: when you go underground you don't make structures, you make spaces. The structures are already there. In abundance. They're called bedrock.

Sure, living underground can be a bit oppressive. However, it won't be the first time humanity starts settling a planet by living in caves.

As someone who spends their time looking at fractured borehole wall rock, I can tell you that it is not the panacea people think it is. Studies of lunar and Martian base construction mention it, then toss it aside because of the problems.

You have to physically cut (heavy equipment) and remove it (heavy equipment), whilst keeping the support structure intact through pillars or rockbolts and shotcrete, and even then it crumbles and collapses. Earthmoving equipment depends on its weight for purchase. On Mars, these things are reduced. Your tunnel boring machine could start turning on its own axis if it's not securely anchored.

Typical depths to competent bedrock on Earth are on the order of 20-30m. On Mars, it's a complete unknown.

If for some reason you are in a section that is cut off in an emergency, someone has to actively tunnel to get to you. A structural failure would mean tonnes of rock collapsing on you. If you are digging the tunnel, you can lose your tunnelling machine to structural failure. Or worse, you could discover that competent bedrock is absolutely nonexistent down to 50m.

Assuming you overcome all these challenges, and seal the tunnels with sintered concrete / vitrification, build in escape stairways, you then discover that because you have landed in an area with permafrost for propellant and water, the waste heat from your underground habs has started to melt it...

*"You" being the hypothetical Martian settlers

Now there are ways to build underground on Mars, but hiring The Boring Company is not going to be the solution. Lava tubes are there, vitrified and easy to seal. Cutting into a mesa like in Red Mars which was mentioned upthread is another valid idea, although subject to the questions of rock competency I would ask.

Thanks for your great contribution in response to my posting!

For sure tunnelling in bedrock is fraught with difficulties. We agree on that.

However, the relevant question is: how big are the difficulties compared to the difficulties of other methods?

This is where I see several advantages of tunnelling.

- The major limitation of working on Mars is the mass budget. Energy is there in abundance (solar or small nuclear reactor), but there is no getting around that you are severely limited in how much material you can land on Mars.

In the initial stage it is obvious that the habs will just be the spaceships. However, when you move beyond that stage how will you expand? With prefab habs? Building habs on the surface? Both methods are mass prohibitive. Even if you pile regolith on surface structures you still need to bring those structures in the first place.

This is why the holy grail for expanding the interior volume on Mars involves going underground. And it needs to be in a structurally self-sustaining and self-pressurized interior volume.

I hear you when you say that lots of caves and tunnels on Earth are not structurally self-sustaining; However, there ARE also very many self-sustaining underground habitats. The geology of Earth allows them in a multitude of places and I have not read that Mars should be any different; If anything Mars is more geologically stable than Earth (less erosion, no tectonics, etc).

It will take a thorough reconnaissance campaign to find just the right spot, a spot which contains stable solid bedrock near a water resource, preferably allowing a horizontal entrance from the surface. As they say: "location is everything."

That's also why lava tubes, enticing though they are, probably won't do, since it would require a minor miracle to find one in just the right place. Another problem with lava tubes is sealing the entrance, which may be of a huge diameter. If you do your own tunnelling it should prove relatively straightforward to plug the entrance.

When tunnelling you only need machinery and energy (and the energy is there). The rest, i.e. the MASS LIMITED raw materials, are already there.

It is pretty clear to me that it is the reason why Musk is actively exploring exponential improvements in tunneling technology. He has taken a first principles approach to the settling of Mars and come to the same conclusion as the one I (and many others) are proposing. Yes, tunnelling on Mars will be devilishly difficult, but it is the best way to attempt limitless expansion (in theory) of habitable volume on a very mass-limited budget.   
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/06/2018 03:57 pm
I see this thread has picked up again!

I will be working on a design for the Mars Society Colony prize, and I guess I might as well post my stuff here, since I am hoping to make an amazing design!  And I will be recycling some of my earlier work.

The core element in the design is a tunnel system.  I would use  Roadheader(s) to make the tunnel in what I hope would be fairly soft stone, clay/sandstone  rocky mixture, in one of the partially erosion filled craters. 
Then build structural pressure resistant linings inside the tunnels.  The linings would be offset from the walls, so most thermal transfer would be by radiation, as the space between the walls will be at Martian atmospheric pressure.
The liners would be made from Compressed Earth Bricks (CEB), made on the spot.  I'm still looking into if I need to add some kind of cement for waterproofing and air tightness.  But I'm planning for some continuous leakage.
Te actual strength of the liners would come from external hoops of carbon fiber wires, post tensionned, eventually replaced by locally produced steel.  Longitudinal strength would be from rods set between the blocks.

I'm looking at intersections, and will try to figure out a reasonable way of making them, as I want a complex multi tube system for a richer environment.

The base will be insulated by the vacuum and low emissivity coatings, so it will overheat and require active cooling, probably using air currents, but perhaps some circulation water as well.

I'll include a number of surface domes for a more varied environment.

I'm open to suggestions and ideas, as I've got till the end of March to finish the thing.
The blocks are 400mm x 400mm x 1000mm..  That might be too big for realistic CEB, but there are some failry large elements visible on the net.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 12/06/2018 06:36 pm
I see this thread has picked up again!

I will be working on a design for the Mars Society Colony prize, and I guess I might as well post my stuff here, since I am hoping to make an amazing design!  And I will be recycling some of my earlier work.

The core element in the design is a tunnel system.  I would use  Roadheader(s) to make the tunnel in what I hope would be fairly soft stone, clay/sandstone  rocky mixture, in one of the partially erosion filled craters. 
Then build structural pressure resistant linings inside the tunnels.  The linings would be offset from the walls, so most thermal transfer would be by radiation, as the space between the walls will be at Martian atmospheric pressure.
The liners would be made from Compressed Earth Bricks (CEB), made on the spot.  I'm still looking into if I need to add some kind of cement for waterproofing and air tightness.  But I'm planning for some continuous leakage.
Te actual strength of the liners would come from external hoops of carbon fiber wires, post tensionned, eventually replaced by locally produced steel.  Longitudinal strength would be from rods set between the blocks.

I'm looking at intersections, and will try to figure out a reasonable way of making them, as I want a complex multi tube system for a richer environment.

The base will be insulated by the vacuum and low emissivity coatings, so it will overheat and require active cooling, probably using air currents, but perhaps some circulation water as well.

I'll include a number of surface domes for a more varied environment.

I'm open to suggestions and ideas, as I've got till the end of March to finish the thing.
The blocks are 400mm x 400mm x 1000mm..  That might be too big for realistic CEB, but there are some failry large elements visible on the net.
Sounds like an interesting project. Perhaps the tunnelling approach and the lava tube approach are not mutually exclusive. If a suitable lava tube can be found with a shallow angle that is accessible and goes deep enough why not use the lava tube to access deeper layers of rock directly without having to dig vertically first? Just dig into the wall of the lava tube and keep going. Could also build some habitat elements in the lava tube and cover them with spoil from the tunnelling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/06/2018 07:15 pm
Good point. Only question: will the lava tube be in the right spot?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/06/2018 07:20 pm
I see this thread has picked up again!

I will be working on a design for the Mars Society Colony prize, and I guess I might as well post my stuff here, since I am hoping to make an amazing design!  And I will be recycling some of my earlier work.

The core element in the design is a tunnel system.  I would use  Roadheader(s) to make the tunnel in what I hope would be fairly soft stone, clay/sandstone  rocky mixture, in one of the partially erosion filled craters. 
Then build structural pressure resistant linings inside the tunnels.  The linings would be offset from the walls, so most thermal transfer would be by radiation, as the space between the walls will be at Martian atmospheric pressure.
The liners would be made from Compressed Earth Bricks (CEB), made on the spot.  I'm still looking into if I need to add some kind of cement for waterproofing and air tightness.  But I'm planning for some continuous leakage.
Te actual strength of the liners would come from external hoops of carbon fiber wires, post tensionned, eventually replaced by locally produced steel.  Longitudinal strength would be from rods set between the blocks.

I'm looking at intersections, and will try to figure out a reasonable way of making them, as I want a complex multi tube system for a richer environment.

The base will be insulated by the vacuum and low emissivity coatings, so it will overheat and require active cooling, probably using air currents, but perhaps some circulation water as well.

I'll include a number of surface domes for a more varied environment.

I'm open to suggestions and ideas, as I've got till the end of March to finish the thing.
The blocks are 400mm x 400mm x 1000mm..  That might be too big for realistic CEB, but there are some failry large elements visible on the net.
Sounds like an interesting project. Perhaps the tunnelling approach and the lava tube approach are not mutually exclusive. If a suitable lava tube can be found with a shallow angle that is accessible and goes deep enough why not use the lava tube to access deeper layers of rock directly without having to dig vertically first? Just dig into the wall of the lava tube and keep going. Could also build some habitat elements in the lava tube and cover them with spoil from the tunnelling.
You can put a pressurized habitat in a lava tube.  that is basically what National Geographic proposed in a recent issue.  You could eventually build the habitats using exclusively local materials.
As lavatubes are, as far as I know, essentially basaltic, we could probably develop a local industry using basalt fibers in a organic or metallic matrix, with the main bulk of the habitats sintered basalt or even steel, if there is iron nearby.
However, for the purpose of the colony design, I will presume the colonists did not identify a handy tube with large amounts of water nearby, but have to create the entire habitat from scratch.  the difference will essentially be the power required for digging (about 1-2 kWh per m3 in my rule of thumb for the moment) and hauling the tunnel material, so one could argue they are essentially the same project, with the artificial tunnel one being more conservative.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/06/2018 07:28 pm
Good point. Only question: will the lava tube be in the right spot?
I'm guessing it will not be.  Otherwise, I think both solutions are fairly similar, the main cost difference being the rate of use of the digging equipment, thousands of hours for tunnels vs hundreds for tubes.  I expect sintered basalt blocks are more expensive the CEB blocs, but that hardly offsets the digging costs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/07/2018 12:23 am
Te actual strength of the liners would come from external hoops of carbon fiber wires, post tensionned, eventually replaced by locally produced steel. Longitudinal strength would be from rods set between the blocks.

Why not extruded basalt? (And not just basalt fibre in a matrix. Extruded basalt rods and mesh are already used in building to reinforce concrete. Well, technically the concrete is the matrix, but you get what I mean. Half inch rods are not "fibre".)

that is basically what National Geographic proposed in a recent issue.

And that god-awful series they made.



how will you expand? With prefab habs? Building habs on the surface? Both methods are mass prohibitive. Even if you pile regolith on surface structures you still need to bring those structures in the first place.

If you can't build an airtight shell, IMO you're not capable of settling Mars.

A basic airtight shell is the equivalent of building a lean-to in a forest. It's the absolute technological minimum cost of entry if you expect to do more than short exploration-and-return.

When tunnelling you only need machinery and energy (and the energy is there). The rest, i.e. the MASS LIMITED raw materials, are already there.

Plus the consumables of the machines.

If you want to build an airtight chamber in raw rock, the walls have to be non-permeable, that rules out soft rock, if you want it to self-support over fairly large areas, that also rules out soft-rock. So you're looking at hard granites. You are going to be consuming a surprising amount of parts to keep the, for example, road-headers running. If that mass is greater than the mass of a shell equivalent to that volume, you haven't saved anything.

Likewise, is the mass of digging equipment necessary for cutting underground structures higher than the mass of equipment for making ISRU airtight shells?

(This argument holds for my suggestion of cut'n'cover. You do need machines to work regolith anyway, but if you bury every hab, the rate of wear on those machines is much higher than if you're just levelling roads and landing-pads.)

It is pretty clear to me that it is the reason why Musk is actively exploring exponential improvements in tunneling technology.

Perhaps, but it's worth noting that the savings he suggests came from reducing the diameter of the tunnel, by using electric "skateboards" instead of having to have full lanes for running cars and full height for trucks. Halve the diameter, quarter the volume dug. He hasn't actually changed tunnel boring the way he has launch costs, distributed power storage, and electric cars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: matthewkantar on 12/07/2018 12:59 am
If an arch of loose stone can be built, a dome can be built. Pile an arbitrary tonnage of stone on top of the dome, don't worry about small gaps.  Insert a one piece membrane with an integrated airlock and you have a pretty good shelter. No tools needed, just gather rocks. Hand carryable rocks will be 2.5 times larger than they are on earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/07/2018 07:05 am
Good point. Only question: will the lava tube be in the right spot?

This is a good question, one which I hope to answer in MSc thesis (still at the proposal stage). But I can tell you that most lava tubes are in the Tharsis Montes region, which, since it lacks sedimentary runoff, doesn't have a lot in the way of promising surface minerals: hydrates, aluminosillicates etc. They're also at higher altitudes and latitudes. But the ones near Noctis Landing, near the equator and feeding into Valles Marineris, look like promising candidates. I think that's where the Mars TV series is located, too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/07/2018 08:28 am
Earthmoving equipment depends on its weight for purchase. On Mars, these things are reduced.

As I understand it, some diggers (like TBMs) don't rely on weight, but push against their previous anchor points. I suspect something similar will need to be done for all earthmoving equipment. Deployable anchors that dig in behind any vehicle when it needs to push forward.

This would be required for all surface work, even just a grader, so it's a general problem, not just for underground work.

The gripper force is dictated by a number of things, including the weight of the TBM. But for the concrete-laying types (ie the ones that don't drill through hard, competent rock) they also push against the edges of the concrete that has been laid. Gravity also affects a TBM as the rock chips fall through gutters in the cutting disc into a hopper and out a chute at the back. Alternatively, they go into a slurry and get pumped out back.

Speaking of pumping, TBMs convert all of their input energy into heat (hundreds of kilowatts even for a small borer, a megawatt for one large enought to dig comfortably sized tunnels). About half of that goes into the broken rock, a quarter or so gets carried out by the slurry (if you have it). The rest of it, on Mars, must be handled by coolant cables. Those must go out to the top to a radiator array.

Quote
you then discover that because you have landed in an area with permafrost for propellant and water, the waste heat from your underground habs has started to melt it...

To be fair, you aren't going to "discover" this after-the-fact. Civil engineering isn't new. Assaying rock, making stable underground structures, understanding water movement, etc, is all stuff we do already. The maths needs to get tweaked for Mars (less gravity, pressure difference), but the basis for the maths is the same.

Post-hoc sarcasm tag. However, rocks can behave in unexpected fashions.

Quote
Cutting into a mesa like in Red Mars which was mentioned upthread is another valid idea, although subject to the questions of rock competency I would ask.

Cutting into a mesa is cutting into bedrock.

There's a distinction between competent and weathered bedrock which is why I bring it up. The walls of a mesa or plateau are a continually weathering face (or at least weathered and then stopped, in the case of Mars). Generally (though I'm no geotechnical engineer), you can throw concrete at bad ground, I'm just saying it won't be a straightforward exercise.

Quote
Lava tubes are there, vitrified and easy to seal.

The latter is debatable. We don't know how structurally sound any tube would be, how permeable/airtight, how clear. We'd have to do the same engineering analysis as with any underground work. (The advantage is that it is, nonetheless, pre-dug.)

As I've mentioned many times, my favourite part of lava tubes is that anything underground will have a temperature that is the average of the surface temperature (heat-pulses mush together the deeper you go). For most places on Mars, even at the equator, lava tubes would be below freezing. Hence water vapour that heats up on the surface will freeze out in the tubes. I suspect that a short way inside from any skylight or breach will be a solid plug of water ice. (Maybe CO₂ as well, depending on the temp.)

Radiation shielding, huge excavated volumes, water in a nice solid filtered form. What's not to love.

Well, most lava tubes run down at a slight angle, especially in the Tharsis Montes regions. There would also be slope winds from the diurnal pressure changes which I'm guessing would cause the tubes to "breathe," carrying water vapour in or out. So an ice plug does not sound at all out of place.

The issue with tunnelling as a solution is that people see a TBM and think it's just this one machine which makes holes, when in fact it's an entire construction solution with the added complexity of a TBM.

But the tunnels are lined with precast concrete blocks made on the surface and sequentially bolted into place. There's gravel and grouting between the tunnel wall and the blocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/07/2018 08:55 am
Also not being a Geotechnical engineer, I'm wondering if a good place to tunnel would be the base of a five or six kilometre high cliff in Valles Marineris.  Would this likely be Competent Bedrock ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/07/2018 09:25 am
Also not being a Geotechnical engineer, I'm wondering if a good place to tunnel would be the base of a five or six kilometre high cliff in Valles Marineris.  Would this likely be Competent Bedrock ?

It would mostly be loose rocks and soil for several hundred metres. The deeper you tunnel towards the actual base of the cliff, the higher the pressure over your head. By the time you are directly underneath the top of the cliff, you have the equivalent of two kilometres of Earth rock bearing down on you. At those depths, rock is basically plastic and tunnels are eventually squeezed shut.

But Valles Marineris is not actually a cliff, more like a medium slope (20 or so degrees) in most places. The vertical scale is heavily exaggerated in the 3D flyarounds you see.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/07/2018 09:38 am
Well, there goes my plans to BASE jump off the top.

Anyway.  In that case, what about somewhere a little smaller, like Ius or Euchus Chasma ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/07/2018 10:07 am
Well, there goes my plans to BASE jump off the top.

Anyway.  In that case, what about somewhere a little smaller, like Ius or Euchus Chasma ?

That's a bloody good question which needs answering. Generally slopes on Mars are like maximum 45 degrees due to scree buildup and so on. But knowing where really steep slopes would be is also useful. I'll use MOLA data to try figure it out. Actually, no... it'll have to be HIRISE stereo because MOLA data points are ~400m apart.

The cliffs in Echus Chasma are four 2.5 kilometres tall (slope is ~45 degrees):

(https://apod.nasa.gov/apod/image/0807/echuschasma_marsexpress_big.jpg)

Then there are the steep, smooth cliffs of the North Pole region. These are about two km tall (but I suspect actually 800m), slope is ~80 degrees:

(https://apod.nasa.gov/apod/image/0503/marscliffs_express_big.jpg)

You could ski your way to a BASE jump  ;D
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/07/2018 01:50 pm
Te actual strength of the liners would come from external hoops of carbon fiber wires, post tensionned, eventually replaced by locally produced steel. Longitudinal strength would be from rods set between the blocks.

Why not extruded basalt? (And not just basalt fibre in a matrix. Extruded basalt rods and mesh are already used in building to reinforce concrete. Well, technically the concrete is the matrix, but you get what I mean. Half inch rods are not "fibre".)

that is basically what National Geographic proposed in a recent issue.

And that god-awful series they made.



how will you expand? With prefab habs? Building habs on the surface? Both methods are mass prohibitive. Even if you pile regolith on surface structures you still need to bring those structures in the first place.

If you can't build an airtight shell, IMO you're not capable of settling Mars.

A basic airtight shell is the equivalent of building a lean-to in a forest. It's the absolute technological minimum cost of entry if you expect to do more than short exploration-and-return.

When tunnelling you only need machinery and energy (and the energy is there). The rest, i.e. the MASS LIMITED raw materials, are already there.

Plus the consumables of the machines.

If you want to build an airtight chamber in raw rock, the walls have to be non-permeable, that rules out soft rock, if you want it to self-support over fairly large areas, that also rules out soft-rock. So you're looking at hard granites. You are going to be consuming a surprising amount of parts to keep the, for example, road-headers running. If that mass is greater than the mass of a shell equivalent to that volume, you haven't saved anything.

Likewise, is the mass of digging equipment necessary for cutting underground structures higher than the mass of equipment for making ISRU airtight shells?

(This argument holds for my suggestion of cut'n'cover. You do need machines to work regolith anyway, but if you bury every hab, the rate of wear on those machines is much higher than if you're just levelling roads and landing-pads.)

It is pretty clear to me that it is the reason why Musk is actively exploring exponential improvements in tunneling technology.

Perhaps, but it's worth noting that the savings he suggests came from reducing the diameter of the tunnel, by using electric "skateboards" instead of having to have full lanes for running cars and full height for trucks. Halve the diameter, quarter the volume dug. He hasn't actually changed tunnel boring the way he has launch costs, distributed power storage, and electric cars.
Extruded basalt is ok if we set up in a basaltic area.  I'm thinking more of settling in a sediment rich area.  Then the equivalent would be fiber glass from SiO2.  I think the energy requirement to make steel wire may be similar to the energy requirement to make fiber and the fiber binder. 

Cut and cover vs tunneling machines is not always a clear cut decision even here on Earth.  The consensus is cut and cover is cheaper, but if the Boring company really improves boring processes by a factor of 10, then boring would become chepaer most of the time, I expect.
And for the base, we select the rock formation for optimum conditions.  On Earth, in most cases, cities are pre existing for completely different reasons, and the rock is not of very good quality, tunnel wise.  So excavation usually wins.

I suggest using soft rock, but strong tunnel liners.  I don't expect any rock to really be competent against 15 psi of air, so liners of some sort will always be required anyway, even in granite or basalt.



Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/07/2018 01:55 pm
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

Every construction and mining site today starts with a visit from one of these guys.

The rig can stay at an interesting spot for a few days and drill cores, then change crews (using a second shuttle vehicle carrying supplies) and keep drilling.  When the core box is full it returns home for analysis of the cores.

My guess is that the range would be about 200 km from home base. Up to 400 km with a way station (a way station being a solar array with a battery pack, a Supercharger station, in effect).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/07/2018 02:03 pm
And here is the second element, a roadheader with four to six dump trucks.  100 tonnes for the roadheader, about 40 to 60 tonnes for the trucks.
Not illustrated here is the battery swapper truck ,that carries batteries in and out more or less continuously to power the roadheader.

The roadheader has a rated output of 350 m3 per hour.  This would allow for the excavation of the volume of a suburban house every 2 hours! The entire volume of the Starship in three.  Of course, the system througput is much lower, one would hope at least 10% of that, so perhaps about one house per day.  Present performance of roadheader is usually lower than 35m3 per hour, but that is the type of ratios the Boring company is trying to improve through automation, batteries and use of locally produced liners.

A battery powered roadheader will run much cooler than a diesel powered one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/07/2018 11:34 pm
Perhaps not my most convincing machine, but part 3 of my grand scheme, a kludge built on Mars:

Hopper, additive hopper, crusher and press.  A Compact Earth Block system

Plus a pile of CEBs.   And a little utility machine.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/07/2018 11:36 pm
Then there are the steep, smooth cliffs of the North Pole region. These are about two km tall (but I suspect actually 800m), slope is ~80 degrees:

(https://apod.nasa.gov/apod/image/0503/marscliffs_express_big.jpg)

That's my bet for a first base. Tunnel into the base of the cliffs. From the tunnelled habitat drill small tubes upwards into the bottom of the glaciers. Pump hot air into the tubes and collect the water running down. Make rocket fuel and grow hydroponics.

In addition the lay-out of the cliffs lends itself to naturally sheltered landing sites for the spaceships, to avoid pelting structures and previously landed spaceships with rocks.

Also such a landscape is highly motivational due to its sheer beauty (and cliffs).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/07/2018 11:54 pm
I'm wondering if a good place to tunnel would be the base of a five or six kilometre high cliff in Valles Marineris.
It would mostly be loose rocks and soil for several hundred metres. The deeper you tunnel towards the actual base of the cliff, the higher the pressure over your head. By the time you are directly underneath the top of the cliff, you have the equivalent of two kilometres of Earth rock bearing down on you. At those depths, rock is basically plastic and tunnels are eventually squeezed shut.
But Valles Marineris is not actually a cliff, more like a medium slope (20 or so degrees) in most places. The vertical scale is heavily exaggerated in the 3D flyarounds you see.

You also don't want to build near the base of any cliff because there's a probably a reason it's a cliff.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/08/2018 02:04 am
Only question: will the lava tube be in the right spot?

My point was that the lava tube itself might innately be the right spot. Not just giving you shelter, but water at well.

Sure, you might not have loads of high quality metal ore around, but initially you can use a couple of billion years of accumulated unweathered metallic meteorite debris, which will be fairly evenly spread around the planet. (And, IMO, that's something you'd do anyway, even if your first settlement was right on top of alternating layers of haematite and bauxite.)

By the time you've cleared all the metallic iron around you, you'll need to be large enough for specialised mining and hence large enough to support remote-site mines and associated secondary settlements. And you will need multiple mines because you generally won't get enough elements from a single spot, iron/aluminium/copper/uranium/sulphur/phosphorus/arsenic, etc etc etc, no matter how free you are to pick your initial site. (Or at least not discoverable from orbital surveys and minimal ground work.)



But the tunnels are lined with precast concrete blocks made on the surface and sequentially bolted into place. There's gravel and grouting between the tunnel wall and the blocks.

That was a point I was trying to make to Oersted previously. In order to make a viable underground volume, if you end up have to make a structural or pressure vessel anyway, how are you saving anything from making the same structural/pressure-vessel and leaving it on the surface (or covering it with regolith.) Or if excavating a large volume uses more resources (parts/labour/energy/etc) than the machinery needed to build a shell on the surface, how is it worth it?

Or how much energy does it take to excavate each cubic metre of suitable rock (if you don't want to also manufacture a lining)? Vs how much energy does it take to merely enclose an equivalent volume on the surface with ISRU material? (Note cube/square.)

I think building underground is one of those ideas that seems like a "simple" solution (like transparent greenhouses, or domes) but when you add in all the things you need in order for it to work, it ends up being harder than solving the initial problem(s) directly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/08/2018 02:30 am
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

On Mars I'd expect the wheels to be more spread out and with greater ground clearance.

And particularly with independent-wheel electric drives, it's mechanically simpler than trying to run a single power-source through multiple axles, even allowing independent all-wheel steering. You might end up with a modular chassis-drive-steer components, like the EFT-truck concept. (Although with more clearance, you need to travel over raw terrain. Unless the very first vehicle is a tracked dozer-grader. [edit: Turns out they have adjustable lift, tons of clearance.]) Connect two drive modules and it's a 4x4 rover chassis, two and a cabin and it's a manned rover. A third and it's a general-purpose 6x6 utility chassis. Five and it's a loader. 10-15 and it's a multi-articulated long distance transport. Oops, did your truck break? Just grab three modules off the long-hauler and swap over your cabin and service units and go back to working while we salvage what we can off the old parts.

(https://i.ytimg.com/vi/bhZbp2qpf0c/maxresdefault.jpg) (https://i.ytimg.com/vi/bhZbp2qpf0c/maxresdefault.jpg)

(https://i.pinimg.com/originals/b8/68/f2/b868f226befe23402dd5d68101647217.jpg) (https://i.pinimg.com/originals/b8/68/f2/b868f226befe23402dd5d68101647217.jpg)

[It's the lots-of-standard-units-because-it's-electric concept I'm interested in. (Or hybrid-electric in EFT's case.)]

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 12/08/2018 02:40 am

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
eh, ICE has the same problem when the methane tanks are full.
On the other hand, though it risks complicating the design and is climate dependant, what about a atmospheric water condensor hooked up to an ice cube mechine and a shadecloth? The idea being to store water outside of a tank, for the next rover to come by and take back to the fuel plant.

it'll be lossy as all hell, but since you only run it when the batteries are full, lossy with unlimited storage beats standing around doing nothing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/08/2018 11:09 am
eh, ICE has the same problem when the methane tanks are full.

(And LOx tanks.) However, for an equivalent mass, methalox is denser than batteries. Moreso, for the way-station itself, tanks with the same mass as the entire battery-pack when transported empty to the site, can have store vastly, vastly more energy than the batteries. (Hence the solar arrays can work longer to fill those tanks.) And the tanks can be built locally at a much lower technology level of the settlement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/08/2018 01:23 pm
Taking into account conversion inefficiencies and the need to carry LOx, and the difference between batteries and ICE is pretty small on Mars. And some kind of batteries actually exceed ICE.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 12/08/2018 01:53 pm
Taking into account conversion inefficiencies and the need to carry LOx, and the difference between batteries and ICE is pretty small on Mars. And some kind of batteries actually exceed ICE.

They will need to consider battery chemistries that can be produced from ISRU on Mars, which might have lower energy density than Li, but not need to be transported all the way from Earth. Solar energy capture will be a critical path and they need to do as much of it as possible in different modes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/08/2018 03:15 pm
Truck fleet from a common base.

Basically one tonne per wheel loading. 4 wheels to 10 or even 12 if we have a double front axle like the large cement trucks.  But the most common are four and six.  I expect the extra rear axle is also a steering one.

The rear axle is additive, just as described by Paul 451 (good idea!)

All electrical, with 200 kWh core battery. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/08/2018 03:33 pm
I'm working with a solar power base cost af a bit less than 1 $ per kWh, with the solar arrays from Earth, 20 years of operation and a very partial battery back up.  Surface transportation costs are a fraction of food and fuel production costs, so the useful optimisations are in fuel production and food production.  There will be about 1 charging station for 100 solar power arrays a the colony, so there is little point in optimising the charging stations.  When the exploration is over in one area, the array can be moved.  Arrays will usually be set up on long and actively travelled routes.
Folded and deployed solar array shown.  192 m2, 14 kW peak, 140 kWh per day on good days. 288 kG mass (no battery).
40 kWh per day during dust storms.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/09/2018 05:18 pm
Taking into account conversion inefficiencies and the need to carry LOx, and the difference between batteries and ICE is pretty small on Mars. And some kind of batteries actually exceed ICE.

They will need to consider battery chemistries that can be produced from ISRU on Mars, which might have lower energy density than Li, but not need to be transported all the way from Earth. Solar energy capture will be a critical path and they need to do as much of it as possible in different modes.
The first decade on Mars will need to include a lot of geological exploration, including satellite obervations and surveys using drones, and latter geoplogists with hammers and drilling rigs.  Lithium, as a salt, may have interesting concentrations in old lake beds, perhaps?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/09/2018 05:22 pm
eh, ICE has the same problem when the methane tanks are full.

(And LOx tanks.) However, for an equivalent mass, methalox is denser than batteries. Moreso, for the way-station itself, tanks with the same mass as the entire battery-pack when transported empty to the site, can have store vastly, vastly more energy than the batteries. (Hence the solar arrays can work longer to fill those tanks.) And the tanks can be built locally at a much lower technology level of the settlement.
There will only be a very few way stations compared to the number of solar panels required for food and propellant production.  I think it will probbly be more interesting to invest ressources in time and material in cleaning the large solar arrays near the colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/09/2018 05:27 pm

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
eh, ICE has the same problem when the methane tanks are full.
On the other hand, though it risks complicating the design and is climate dependant, what about a atmospheric water condensor hooked up to an ice cube mechine and a shadecloth? The idea being to store water outside of a tank, for the next rover to come by and take back to the fuel plant.

it'll be lossy as all hell, but since you only run it when the batteries are full, lossy with unlimited storage beats standing around doing nothing.
Depends on what the vehicles going through the way stations are carrying.  If they carry supplies on the way up and geological samples on the way down, or tired geologists, then there might not be much margin for water/propellant recovery. 
Some of the power could be used for telecommunications, and perhaps it would be interesting to power drones, or similar light vehicles from the way stations to explore the intermediate areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/09/2018 05:30 pm
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

On Mars I'd expect the wheels to be more spread out and with greater ground clearance.

And particularly with independent-wheel electric drives, it's mechanically simpler than trying to run a single power-source through multiple axles, even allowing independent all-wheel steering. You might end up with a modular chassis-drive-steer components, like the EFT-truck concept. (Although with more clearance, you need to travel over raw terrain. Unless the very first vehicle is a tracked dozer-grader. [edit: Turns out they have adjustable lift, tons of clearance.]) Connect two drive modules and it's a 4x4 rover chassis, two and a cabin and it's a manned rover. A third and it's a general-purpose 6x6 utility chassis. Five and it's a loader. 10-15 and it's a multi-articulated long distance transport. Oops, did your truck break? Just grab three modules off the long-hauler and swap over your cabin and service units and go back to working while we salvage what we can off the old parts.

(https://i.ytimg.com/vi/bhZbp2qpf0c/maxresdefault.jpg) (https://i.ytimg.com/vi/bhZbp2qpf0c/maxresdefault.jpg)

(https://i.pinimg.com/originals/b8/68/f2/b868f226befe23402dd5d68101647217.jpg) (https://i.pinimg.com/originals/b8/68/f2/b868f226befe23402dd5d68101647217.jpg)

[It's the lots-of-standard-units-because-it's-electric concept I'm interested in. (Or hybrid-electric in EFT's case.)]

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
These vehicles are concepts?
I think it would be great to have the way stations as storage places for water and oxygen.  Perhaps if they can be arranged in a loop it might make sense to have 'harvesters' move from one way station to the next.  Then the way stations would serve a dual purpose.  There may not be a specific advantage to having all of the production equipment in a single spot, if we have distributed solar, might as well spread it over a wide are.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/09/2018 07:34 pm
>
These vehicles are concepts?

>

ETF Mining... (http://www.etf.equipment/etf-mining-trucks/etf-mining-trucks/)

https://youtu.be/JzOLRF53-_g

https://youtu.be/RfQbKXw-oOI



Title: Re: Envisioning Amazing Martian Habitats
Post by: groknull on 12/09/2018 07:39 pm
Here is my first element for my tunnel system: a Mars adapted drill rig, with a extended stay cabin and a large solar array, battery system for power.

On Mars I'd expect the wheels to be more spread out and with greater ground clearance.

And particularly with independent-wheel electric drives, it's mechanically simpler than trying to run a single power-source through multiple axles, even allowing independent all-wheel steering. You might end up with a modular chassis-drive-steer components, like the EFT-truck concept. (Although with more clearance, you need to travel over raw terrain. Unless the very first vehicle is a tracked dozer-grader. [edit: Turns out they have adjustable lift, tons of clearance.]) Connect two drive modules and it's a 4x4 rover chassis, two and a cabin and it's a manned rover. A third and it's a general-purpose 6x6 utility chassis. Five and it's a loader. 10-15 and it's a multi-articulated long distance transport. Oops, did your truck break? Just grab three modules off the long-hauler and swap over your cabin and service units and go back to working while we salvage what we can off the old parts.

(https://i.ytimg.com/vi/bhZbp2qpf0c/maxresdefault.jpg) (https://i.ytimg.com/vi/bhZbp2qpf0c/maxresdefault.jpg)

(https://i.pinimg.com/originals/b8/68/f2/b868f226befe23402dd5d68101647217.jpg) (https://i.pinimg.com/originals/b8/68/f2/b868f226befe23402dd5d68101647217.jpg)

[It's the lots-of-standard-units-because-it's-electric concept I'm interested in. (Or hybrid-electric in EFT's case.)]

(a way station being a solar array with a battery pack, a Supercharger station, in effect).

This is clever. I occasionally hear a throw-away mention of "way stations" to extend range, I've yet to see anyone actually flesh out a minimum version of such a thing. Yours lends itself to standardisation.

[This also gets back to battery-vs-ICE/fuel-cell question. It is vastly more efficient to have a solar array charge a battery and a battery power an electric drive, compared to having the solar array power a fuel/oxide-maker, then fuel an inefficient chemical-fuel generator. But in the former case, once that small battery is charged... that array is doing nothing. Are you better off having it trickle-generate and store fuel/oxygen over long periods, for use in bursts? The latter also gives you a handy emergency oxygen supply. Not suggesting that for your Mars-contest entry, not futurey enough for judges.]
These vehicles are concepts?
I think it would be great to have the way stations as storage places for water and oxygen.  Perhaps if they can be arranged in a loop it might make sense to have 'harvesters' move from one way station to the next.  Then the way stations would serve a dual purpose.  There may not be a specific advantage to having all of the production equipment in a single spot, if we have distributed solar, might as well spread it over a wide are.

The EFT MT-240 is/was under construction, and may be in use by now.  It appears to be the pathfinder for a family of modular mining vehicles.
https://i.pinimg.com/originals/a6/55/17/a6551734992c0a3ae5632106fb2f9d6c.jpg
https://www.youtube.com/watch?v=qUPaj5hi8KU

The WTW220E has been in use for a while now.  It uses individual electrically powered bogies.
https://i.pinimg.com/originals/8c/c6/88/8cc6882430dcad0696be68176d0642a4.jpg

Multiple bogie heavy vehicle propulsion is well understood from decades of use in Self Propelled Mobile Transporters (SPMTs).  The WTW220E is proving the use of bogies in very heavy mining trucks.  The EFT MT-240 is expanding the knowledge base to include modularity on the subsystem level, vehicle level, and multi-vehicle level in mining applications.

There appears to be a trend towards multiple bogie systems in mining vehicle designs [1].  AIUI, tire wear is a big issue on mining vehicles.  Individual bogies allow near-zero scrub angles on all tires, reducing tire wear.  In addition, bogies allow raising individual wheel sets to change tires, avoid soft surfaces or hazardous objects, or disable a non-working motor, wheel, or tire.  Also, smaller tires often have lower cost due to higher production volume.

Tire/wheel wear for Mars vehicles probably needs some research.  The Curiosity rover has suffered wheel damage during its lifetime.  Initially it might be useful to choose a drive layout that is highly modular and fault tolerant.

[1] Mining is not my field of expertise.  This is just an observation about heavy vehicle design.

EDIT: Added EFT MT-240 Run 2 YouTube video.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/09/2018 10:15 pm

Tire/wheel wear for Mars vehicles probably needs some research.  The Curiosity rover has suffered wheel damage during its lifetime.  Initially it might be useful to choose a drive layout that is highly modular and fault tolerant.

[1] Mining is not my field of expertise.  This is just an observation about heavy vehicle design.

EDIT: Added EFT MT-240 Run 2 YouTube video.
I think these trucks are way too big for my needs, of for Mars until way latter, but the independant wheel thing certainly has merit, after all the MMSEV uses them.  Haven't seem them out there in the real world though. 
I worked on mining truck garages; the wheels were a big part of the work, they operated at 90 psi and cost a fortune.  Mining trucks lead a simple life: drive down, get loaded, drive up.  The roads are rough, the mining pits rougher.  Maintenance was frequent, and they needed to be cleaned often,  A single 100T truck could carry a ton of oil encrusted dirt on its chassis. They exist because they are more flexible and cheaper than conveyors for the same job.  Automation seems to be rapidly replacing the drivers with remote control though.
For tunnel work I think fairly conventional trucks will do, but I worry about the weels, and the glass transition phase of rubber.  So the wheels I've illustrated are very close to the lunar Jeep wheels, braided wire with some metal inserts.  Wonder why they didn't use these on Mars?
Edit:
I see that are thinking about it:
https://www.mlive.com/news/us-world/index.ssf/2017/11/nasas_new_tires.html
I'll stick with these for the moment then.



Title: Re: Envisioning Amazing Martian Habitats
Post by: groknull on 12/09/2018 11:32 pm

Tire/wheel wear for Mars vehicles probably needs some research.  The Curiosity rover has suffered wheel damage during its lifetime.  Initially it might be useful to choose a drive layout that is highly modular and fault tolerant.

[1] Mining is not my field of expertise.  This is just an observation about heavy vehicle design.

EDIT: Added EFT MT-240 Run 2 YouTube video.
I think these trucks are way too big for my needs, of for Mars until way latter, but the independant wheel thing certainly has merit, after all the MMSEV uses them.  Haven't seem them out there in the real world though. 
I worked on mining truck garages; the wheels were a big part of the work, they operated at 90 psi and cost a fortune.  Mining trucks lead a simple life: drive down, get loaded, drive up.  The roads are rough, the mining pits rougher.  Maintenance was frequent, and they needed to be cleaned ofter,  A single 100T truck could carry a ton of oil encrusted dirt on its chassis. They exist because they are more flexible and cheaper than conveyors for the same job.  Automation seems to be rapidly replacing the drivers with remote control though.
For tunnel work I think fairly conventional trucks will do, but I worry about the weels, and the glass transition phase of rubber.  So the wheels I've illustrated are very close to the lunar Jeep wheels, braided wire with some metal inserts.  Wonder why they didn't use these on Mars?


Independent bogie vehicle designs are very scalable.  Here's an SPMT of about the right dimensions:
https://www.youtube.com/watch?v=tJWTVf7fDeQ

I was wondering the same thing about the Mars rover wheels.  Maybe the tradeoff between rover expected lifetime, distance traveled, development effort, mass, and volume favored a simple cylinder with cleats.  For Mars colonization vehicles, the braided wire wheels you suggest make sense to me.

EDIT: Fixed quotes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 12:41 am

Tire/wheel wear for Mars vehicles probably needs some research.  The Curiosity rover has suffered wheel damage during its lifetime.  Initially it might be useful to choose a drive layout that is highly modular and fault tolerant.

[1] Mining is not my field of expertise.  This is just an observation about heavy vehicle design.

EDIT: Added EFT MT-240 Run 2 YouTube video.
I think these trucks are way too big for my needs, of for Mars until way latter, but the independant wheel thing certainly has merit, after all the MMSEV uses them.  Haven't seem them out there in the real world though. 
I worked on mining truck garages; the wheels were a big part of the work, they operated at 90 psi and cost a fortune.  Mining trucks lead a simple life: drive down, get loaded, drive up.  The roads are rough, the mining pits rougher.  Maintenance was frequent, and they needed to be cleaned ofter,  A single 100T truck could carry a ton of oil encrusted dirt on its chassis. They exist because they are more flexible and cheaper than conveyors for the same job.  Automation seems to be rapidly replacing the drivers with remote control though.
For tunnel work I think fairly conventional trucks will do, but I worry about the weels, and the glass transition phase of rubber.  So the wheels I've illustrated are very close to the lunar Jeep wheels, braided wire with some metal inserts.  Wonder why they didn't use these on Mars?


Independent bogie vehicle designs are very scalable.  Here's an SPMT of about the right dimensions:

I was wondering the same thing about the Mars rover wheels.  Maybe the tradeoff between rover expected lifetime, distance traveled, development effort, mass, and volume favored a simple cylinder with cleats.  For Mars colonization vehicles, the braided wire wheels you suggest make sense to me.

EDIT: Fixed quotes.
Very interesting image.  These vehicles seem to move slowly, but I expect it's more the nature of the load that any specific limitation
Here is version of my common platform with the maximum number of wheels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: groknull on 12/10/2018 01:52 am

Tire/wheel wear for Mars vehicles probably needs some research.  The Curiosity rover has suffered wheel damage during its lifetime.  Initially it might be useful to choose a drive layout that is highly modular and fault tolerant.

[1] Mining is not my field of expertise.  This is just an observation about heavy vehicle design.

EDIT: Added EFT MT-240 Run 2 YouTube video.
I think these trucks are way too big for my needs, of for Mars until way latter, but the independant wheel thing certainly has merit, after all the MMSEV uses them.  Haven't seem them out there in the real world though. 
I worked on mining truck garages; the wheels were a big part of the work, they operated at 90 psi and cost a fortune.  Mining trucks lead a simple life: drive down, get loaded, drive up.  The roads are rough, the mining pits rougher.  Maintenance was frequent, and they needed to be cleaned ofter,  A single 100T truck could carry a ton of oil encrusted dirt on its chassis. They exist because they are more flexible and cheaper than conveyors for the same job.  Automation seems to be rapidly replacing the drivers with remote control though.
For tunnel work I think fairly conventional trucks will do, but I worry about the weels, and the glass transition phase of rubber.  So the wheels I've illustrated are very close to the lunar Jeep wheels, braided wire with some metal inserts.  Wonder why they didn't use these on Mars?


Independent bogie vehicle designs are very scalable.  Here's an SPMT of about the right dimensions:

I was wondering the same thing about the Mars rover wheels.  Maybe the tradeoff between rover expected lifetime, distance traveled, development effort, mass, and volume favored a simple cylinder with cleats.  For Mars colonization vehicles, the braided wire wheels you suggest make sense to me.

EDIT: Fixed quotes.
Very interesting image.  These vehicles seem to move slowly, but I expect it's more the nature of the load that any specific limitation
Here is version of my common platform with the maximum number of wheels.

Excellent.

Your images seem to show mostly rotating joints rather than sliding / telescopic ones.  Sliding interfaces (hydraulic cylinders, beam trolleys, mill/lathe ways, etc.) have issues with fluid loss, seal integrity, surface galling, and swarf/dust contamination. 

Hydraulic cylinder design on Earth is fairly mature - known atmospheric properties, known environmental conditions (dirt, mud, sand, dust, water, etc.), hydraulic fluid selected for specific properties, and seal material and geometry designed for the application and temperature range.

We don't have a lot of data for sliding interfaces on Mars.  (Viking I & II robot arms excepted.)

Given that you worked with/on mining equipment, what is your experience with the robustness and reliability of sliding vs. rotating interfaces on heavy equipment in mechanically harsh environments?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 03:41 am

Very interesting image.  These vehicles seem to move slowly, but I expect it's more the nature of the load that any specific limitation
Here is version of my common platform with the maximum number of wheels.

Excellent.

Your images seem to show mostly rotating joints rather than sliding / telescopic ones.  Sliding interfaces (hydraulic cylinders, beam trolleys, mill/lathe ways, etc.) have issues with fluid loss, seal integrity, surface galling, and swarf/dust contamination. 

Hydraulic cylinder design on Earth is fairly mature - known atmospheric properties, known environmental conditions (dirt, mud, sand, dust, water, etc.), hydraulic fluid selected for specific properties, and seal material and geometry designed for the application and temperature range.

We don't have a lot of data for sliding interfaces on Mars.  (Viking I & II robot arms excepted.)

Given that you worked with/on mining equipment, what is your experience with the robustness and reliability of sliding vs. rotating interfaces on heavy equipment in mechanically harsh environments?

They kept the equipement warm and running pretty much all times in winter, to reduce problems with the cold.
I would expect there would be heat tracing on most lines, and infra red heading as well.  Probably some insulation.
I think there would be flexible extendable jackets to protect sliding surfaces from abrasive dust.  These are not much used on Earth, as they are a nuisance and sealing technology is mature, but poor viscosity might  make these obligatory on Mars.  I don't illustrate these because they are a real pain to model :-)

http://www.filterfocus.co.za/Products/hydraulic-cylinder-protection.html


Machine designers I knew said alumina was probably the worst material for abrasion. Cement was pretty bad as well, but I saw loaders  and screw conveyors working happily away in cement piles.  My guess is that iron oxyde would be OK, but that silica on Mars would be a problem.

In general I think rotating elements are easier.  The problems with rubber and seals on Mars (glass transition phase at low temperatures, probable breakage during cold nights) are obviously solvable, the various rovers being proof of this.

At the mines, the equipement was washed often, and there was a schedule of about ... one month? Before each vehicle was brough in an overhauled.  This was operations, while I was in services, so my knowledge of these numbers is hazy.   The garage in a mining operation was the second largest building after the mill. 

I think one of the important pieces of colony support on the Earth side of things would be a large environmental chamber, where standard equipement could be tested and adapted for Mars operations.

A semi enclosed of fully enclosed garage with a number of bays would be a needed on Mars, I've tried to imagine both open one and enclosed ones in earlier designs.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/10/2018 07:29 am
For enclosing the rotating joints, one option that presents itself is legged vehicles, though they are not as efficient as wheeled ones even on Mars. We certainly have the technology now to do that.

Also: Martian bedrock. Absolutely awful. The fractured rock goes down to 100m. Regolith depth is about 10m, so any shielding you want from that you can get with a simple box cut, emplace the pressure vessel and then pile regolith back on. No underground excavation required (Like Paul451 keeps saying)

It seems like you're going for a side entrance to bedrock through a crater. Crater walls from small impacts generally don't have a thick melt zone on the walls. For this one, looks 1 or 2 km in diameter, at the very base of it you might get a solid melt zone. Most of it would be puddled on the crater floor... in larger craters, crater wall slump covers it with a mass of fractured breccias which buries it to some depth.

The crater wall would probably require reinforcement above the mining zone, with rockbolts, shotcrete and netting. Landslides on Mars are a thing and sending a 250 tonne Starship roaring into the crater every is certainly going to rattle some teacups and start a landslide or two. Beyond the impact melt zone, the rock is just going to be fractured to hell. I would say it's so loose you could probably excavate it with picks and rock drills. The meteorite impact did all the blasting for you.  ;D

A better idea might be to excavate into the upper rim of the crater. The bedrock is uplifted there, cleared of regolith and offers a nice natural decline which goes with the strata. The fracturing caused by the impact usually erodes away almost immediately. The rim of Victoria Crater is a good example. But I would think doing a box cut following the circumference would be easier from a materials handling standpoint, otherwise you need to pour loads of concrete for an apron on very dubious ground.

(https://apod.nasa.gov/apod/image/0707/victoria2_opportunity_big.jpg)

https://www.hou.usra.edu/meetings/lpsc2014/pdf/2217.pdf (https://www.hou.usra.edu/meetings/lpsc2014/pdf/2217.pdf)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/10/2018 09:22 am
And here is the second element, a roadheader with four to six dump trucks.  100 tonnes for the roadheader, about 40 to 60 tonnes for the trucks.
Not illustrated here is the battery swapper truck ,that carries batteries in and out more or less continuously to power the roadheader.

The roadheader has a rated output of 350 m3 per hour.  This would allow for the excavation of the volume of a suburban house every 2 hours! The entire volume of the Starship in three.  Of course, the system througput is much lower, one would hope at least 10% of that, so perhaps about one house per day.  Present performance of roadheader is usually lower than 35m3 per hour, but that is the type of ratios the Boring company is trying to improve through automation, batteries and use of locally produced liners.

A battery powered roadheader will run much cooler than a diesel powered one.

Your roadheader will need coolant lines to a surface radiator farm. None of the heat will be removed by convection as it is on Earth. Or removable heat sinks, since you are going with battery swaps.

The question of tires is a good one. Those titanium wire ones are really only for a small rover that doesn't go very far or fast compared to a hard working mine vehicle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 12/10/2018 10:27 am
I guess there will be a good solution for the tires. But I would like to know how much can one drillhead do. Do they need to exchange the whole drillhead or can they replace single bits? Those drillheads look heavy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/10/2018 10:59 am
Your images seem to show mostly rotating joints rather than sliding / telescopic ones.  Sliding interfaces (hydraulic cylinders, beam trolleys, mill/lathe ways, etc.) have issues with fluid loss, seal integrity, surface galling, and swarf/dust contamination.

However, if you are going to dig or scoop or pile anything, you need to leverage levers, which means telescoping cylinders a good distance from the rotating pivot point. You aren't going to get much loading if you are limited to powered rotating joints.

So it's either a solved problem by the time you deploy or the whole concept of work vehicles on Mars is show stopper.



But I would like to know how much can one drillhead do. Do they need to exchange the whole drillhead or can they replace single bits? Those drillheads look heavy.

With most of these kinds of things, the main impact part is a swappable bit or blade. Sometimes the part the bit/blade attaches to is also swappable, sometimes it's welded on. That's what it looks like with road-headers, swappable bits, sometimes swappable bases sometimes welded. The bits are crazy hard but wear down like they're wet cardboard.

(I haven't been involved in mining, but I grew up around building sites. I recall the "fun" of weekends spent in the garage replacing the individual blades on a trencher. Worse when replacing chain links. Worse when replacing the trailing cog. Worst of all when replacing the drive cog, pulling out the engine was easier. (A trencher is like a chainsaw had sex with a bull-dozer.))
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/10/2018 11:07 am
[ETF/etc]
I think these trucks are way too big for my needs

Go big or go stay home?

but the independant wheel thing certainly has merit, after all the MMSEV uses them.

My point was to go even further into modularity than ETF or MMSEV. Not only would each bogie be independently steerable, drivable and articulated, not only would they be common and swappable between all vehicles, but the chassis itself would be entirely made up of 2-bogie segments (the "decks" in each segment would house batteries and ancillary gear.) The 2-bogie chassis segments connect together to form larger vehicles. Then you add the stuff onto standard connectors on top of the chassis decks.

(I'm also imagining some distance between sections, with multiple optional connectors. Connect at one point and you can articulate the chassis in any direction (roll, pitch, yaw), connect two horizontally and you can only flex vertically (pitch), two vertically and you can only turn horizontally (yaw), connect at three points and they are held rigidly together.)



However, I just remembered you are working on a tunnelling proposal. The vehicles I used as examples all came from open-cut mines. Underground mining trucks and tools tend to be low-slung and long (and highly articulated.)

(https://egbc-images.s3-eu-west-1.amazonaws.com/content/w620/205277.jpg) (https://egbc-images.s3-eu-west-1.amazonaws.com/content/w620/205277.jpg)

(http://img.directindustry.com/images_di/photo-g/40827-5076349.jpg) (http://img.directindustry.com/images_di/photo-g/40827-5076349.jpg)

Which puts you in a catch-22. If you use vehicles optimised for underground work, they'll be hopeless over open terrain, so you'll need even larger (all terrain) flat-bed transport trucks to/from the work-site. OTOH, if you generalise all-purpose/all-terrain work vehicles, you'll make the actual tunnelling more difficult.

[independent wheel things] Haven't seem them out there in the real world though.

It seems to be an electric thing. If you look at proposals for all-electric jets, you see the same massively-multi-engined thing going on. Different scale effects, I guess.

Be interesting to see if electric mining vehicles evolve back to four big wheels when the harsh light of decades of work shines its evil pragmatism on them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 12:26 pm
And here is the second element, a roadheader with four to six dump trucks.  100 tonnes for the roadheader, about 40 to 60 tonnes for the trucks.
Not illustrated here is the battery swapper truck ,that carries batteries in and out more or less continuously to power the roadheader.

The roadheader has a rated output of 350 m3 per hour.  This would allow for the excavation of the volume of a suburban house every 2 hours! The entire volume of the Starship in three.  Of course, the system througput is much lower, one would hope at least 10% of that, so perhaps about one house per day.  Present performance of roadheader is usually lower than 35m3 per hour, but that is the type of ratios the Boring company is trying to improve through automation, batteries and use of locally produced liners.

A battery powered roadheader will run much cooler than a diesel powered one.

Your roadheader will need coolant lines to a surface radiator farm. None of the heat will be removed by convection as it is on Earth. Or removable heat sinks, since you are going with battery swaps.

The question of tires is a good one. Those titanium wire ones are really only for a small rover that doesn't go very far or fast compared to a hard working mine vehicle.
I was hoping the rock might be considered a removable heat sink, as most of the work will be happening to it.  As the drilling head gets hotter it might eventually create evaporation from the surronding rock, if it has, say 10% water content?  Phase change would take up quite a bit of heat.
Radiation would have to provide the rest of the cooling. At 70C with -50 walls and good emissivity I'm getting about 300W/m2. So the road header itself can only radiate a few kW at best, and it has to operate efficiently.
Although the roadheader would have about 300 kW of power, it would be operating on average at about 10% of this, so 30 kW would need to be removed, over an hour that would be 100 000 kJ.  If we can remove 30 tonnes per hour, or 30 000 kg, with 1 kJ/kg Cp,  then the temperature of the rock would need to be raised about 3C to remove 100 000 kJ.  Seems possible.  The road header I'm basing my design on is rated in the Sandvik catalogue at 350 tonnes per hour maximum output so 30 tonnes per hour seems reasonable.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 12:44 pm
[ETF/etc]
I think these trucks are way too big for my needs

Go big or go stay home?

but the independant wheel thing certainly has merit, after all the MMSEV uses them.

My point was to go even further into modularity than ETF or MMSEV. Not only would each bogie be independently steerable, drivable and articulated, not only would they be common and swappable between all vehicles, but the chassis itself would be entirely made up of 2-bogie segments (the "decks" in each segment would house batteries and ancillary gear.) The 2-bogie chassis segments connect together to form larger vehicles. Then you add the stuff onto standard connectors on top of the chassis decks.

(I'm also imagining some distance between sections, with multiple optional connectors. Connect at one point and you can articulate the chassis in any direction (roll, pitch, yaw), connect two horizontally and you can only flex vertically (pitch), two vertically and you can only turn horizontally (yaw), connect at three points and they are held rigidly together.)



However, I just remembered you are working on a tunnelling proposal. The vehicles I used as examples all came from open-cut mines. Underground mining trucks and tools tend to be low-slung and long (and highly articulated.)

(https://egbc-images.s3-eu-west-1.amazonaws.com/content/w620/205277.jpg) (https://egbc-images.s3-eu-west-1.amazonaws.com/content/w620/205277.jpg)

(http://img.directindustry.com/images_di/photo-g/40827-5076349.jpg) (http://img.directindustry.com/images_di/photo-g/40827-5076349.jpg)

Which puts you in a catch-22. If you use vehicles optimised for underground work, they'll be hopeless over open terrain, so you'll need even larger (all terrain) flat-bed transport trucks to/from the work-site. OTOH, if you generalise all-purpose/all-terrain work vehicles, you'll make the actual tunnelling more difficult.

[independent wheel things] Haven't seem them out there in the real world though.

It seems to be an electric thing. If you look at proposals for all-electric jets, you see the same massively-multi-engined thing going on. Different scale effects, I guess.

Be interesting to see if electric mining vehicles evolve back to four big wheels when the harsh light of decades of work shines its evil pragmatism on them.

Well, at least on Mars, for a few centuries, you won't get spring thawing load reductions :-)
A flatbed trailer is about the easiest machine to design in the world.  Two beams one deck and a number of borrowed components.  So moving mining equipment about will not be a problem.
Once the colony gets started, I don't expect the equipment will ever come out again.  The things that are moving rapidly will be the dump trucks, and those will be working in the same environment, be it underground or overground, i.e., crushed rock roads.
My guess is that modern electrics lend themselves to very high redundancy.  And directly driven motors with variators are very flexible indeed.
Surface mining machines are still very much four big wheels (well six, to be nitpicky, as far as the trucks go). But it's a conservative world, mining.  And they like to go bigger and bigger.  I would expect a similar trend in a Martina colony with the tunnels (or habitats, or covered trenches) getting larger and larger as well.

Underground mines are usually designed for the most optimum path to the ore.  So the lowest headroom possible, and the less useless rock possible.  Or for coal, that just happens to mostly exist in large flat beds with low headroom.  That is not necessarily required for an underground colony, that will be built like a road or train tunnel.  High headroom is a requirement for tunnels, not for mines.

Rather than very flexible vehicles, I recommend very flat roads.  More optimum in the long run.  And you can go faster too.

Roadbuilding on Mars.  It seems a straighforward question of pushing boulders aside, crushing some rock for potholes and then... what would make a good roling surface?  Compacted regolith?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 12:53 pm
Your images seem to show mostly rotating joints rather than sliding / telescopic ones.  Sliding interfaces (hydraulic cylinders, beam trolleys, mill/lathe ways, etc.) have issues with fluid loss, seal integrity, surface galling, and swarf/dust contamination.

However, if you are going to dig or scoop or pile anything, you need to leverage levers, which means telescoping cylinders a good distance from the rotating pivot point. You aren't going to get much loading if you are limited to powered rotating joints.

So it's either a solved problem by the time you deploy or the whole concept of work vehicles on Mars is show stopper.



But I would like to know how much can one drillhead do. Do they need to exchange the whole drillhead or can they replace single bits? Those drillheads look heavy.

With most of these kinds of things, the main impact part is a swappable bit or blade. Sometimes the part the bit/blade attaches to is also swappable, sometimes it's welded on. That's what it looks like with road-headers, swappable bits, sometimes swappable bases sometimes welded. The bits are crazy hard but wear down like they're wet cardboard.

(I haven't been involved in mining, but I grew up around building sites. I recall the "fun" of weekends spent in the garage replacing the individual blades on a trencher. Worse when replacing chain links. Worse when replacing the trailing cog. Worst of all when replacing the drive cog, pulling out the engine was easier. (A trencher is like a chainsaw had sex with a bull-dozer.))
The roadheader has swappable teeth.  Likely very hard steel. Probably a great pain to change.   I'm hopping we can find a nice sandstone equivalent on Mars, so minimum wear.  Average downtimes for roadheaders in the litterature seems low, so perhaps it's not too much of a problem.

A lot of mining is actually done with explosives, ammonia based if I recall correctly.  This is not a good alternative on Mars, where the chemical preparation of the explosive will always use more energy than mechanical grinding.  And grinding creates natural sand and gravel, that should be useful.

Some images of the colony grid, based on Compressed Earth Blocks with tension rings/loops.  I'm begining to see the point that this might just as well be built in a trench.  Will look into the specifics of the methods soon.  My deadline is still March!  Anybody know the difference in energy between digging and boring?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/10/2018 01:01 pm
And here is the second element, a roadheader with four to six dump trucks.  100 tonnes for the roadheader, about 40 to 60 tonnes for the trucks.
Not illustrated here is the battery swapper truck ,that carries batteries in and out more or less continuously to power the roadheader.

The roadheader has a rated output of 350 m3 per hour.  This would allow for the excavation of the volume of a suburban house every 2 hours! The entire volume of the Starship in three.  Of course, the system througput is much lower, one would hope at least 10% of that, so perhaps about one house per day.  Present performance of roadheader is usually lower than 35m3 per hour, but that is the type of ratios the Boring company is trying to improve through automation, batteries and use of locally produced liners.

A battery powered roadheader will run much cooler than a diesel powered one.

Your roadheader will need coolant lines to a surface radiator farm. None of the heat will be removed by convection as it is on Earth. Or removable heat sinks, since you are going with battery swaps.

The question of tires is a good one. Those titanium wire ones are really only for a small rover that doesn't go very far or fast compared to a hard working mine vehicle.
I was hoping the rock might be considered a removable heat sink, as most of the work will be happening to it.  As the drilling head gets hotter it might eventually create evaporation from the surronding rock, if it has, say 10% water content?  Phase change would take up quite a bit of heat.
Radiation would have to provide the rest of the cooling. At 70C with -50 walls and good emissivity I'm getting about 300W/m2. So the road header itself can only radiate a few kW at best, and it has to operate efficiently.
Although the roadheader would have about 300 kW of power, it would be operating on average at about 10% of this, so 30 kW would need to be removed, over an hour that would be 100 000 kJ.  If we can remove 30 tonnes per hour, or 30 000 kg, with 1 kJ/kg Cp,  then the temperature of the rock would need to be raised about 3C to remove 100 000 kJ.  Seems possible.  The road header I'm basing my design on is rated in the Sandvik catalogue at 350 tonnes per hour maximum output so 30 tonnes per hour seems reasonable.



I know that with TBM bits, about 40% of the energy goes into the shattered rock and can be considered removed. The remainder stays with the machine through efficiency losses and also the fact that the bit itself will also heat up from the friction without Maxwell's Demon to shovel the heat away.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 12/10/2018 01:04 pm
And here is the second element, a roadheader with four to six dump trucks.  100 tonnes for the roadheader, about 40 to 60 tonnes for the trucks.
Not illustrated here is the battery swapper truck ,that carries batteries in and out more or less continuously to power the roadheader.

The roadheader has a rated output of 350 m3 per hour.  This would allow for the excavation of the volume of a suburban house every 2 hours! The entire volume of the Starship in three.  Of course, the system througput is much lower, one would hope at least 10% of that, so perhaps about one house per day.  Present performance of roadheader is usually lower than 35m3 per hour, but that is the type of ratios the Boring company is trying to improve through automation, batteries and use of locally produced liners.

A battery powered roadheader will run much cooler than a diesel powered one.

Your roadheader will need coolant lines to a surface radiator farm. None of the heat will be removed by convection as it is on Earth. Or removable heat sinks, since you are going with battery swaps.

The question of tires is a good one. Those titanium wire ones are really only for a small rover that doesn't go very far or fast compared to a hard working mine vehicle.
I was hoping the rock might be considered a removable heat sink, as most of the work will be happening to it.  As the drilling head gets hotter it might eventually create evaporation from the surronding rock, if it has, say 10% water content?  Phase change would take up quite a bit of heat.
Radiation would have to provide the rest of the cooling. At 70C with -50 walls and good emissivity I'm getting about 300W/m2. So the road header itself can only radiate a few kW at best, and it has to operate efficiently.
Although the roadheader would have about 300 kW of power, it would be operating on average at about 10% of this, so 30 kW would need to be removed, over an hour that would be 100 000 kJ.  If we can remove 30 tonnes per hour, or 30 000 kg, with 1 kJ/kg Cp,  then the temperature of the rock would need to be raised about 3C to remove 100 000 kJ.  Seems possible.  The road header I'm basing my design on is rated in the Sandvik catalogue at 350 tonnes per hour maximum output so 30 tonnes per hour seems reasonable.



I know that with TBM bits, about 40% of the energy goes into the shattered rock and can be considered removed. The remainder stays with the machine through efficiency losses and also the fact that the bit itself will also heat up from the friction without Maxwell's Demon to shovel the heat away.
And its operating in a near vacuum so that won't help disipate heat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: alexterrell on 12/10/2018 01:12 pm
Not sure about energy, but on Earth, digging is almost always preferred unless:
- The tunnel is very deep - typically more than 10m (or more fora big tunnel)
- You don't want to disturb the surface because it's a City, or Water. 

More important, which can be done with less manual input? Probably both - diggers can be automated (we don't, because operators on Earth are cheap).

I was thinking of something cut and cover.

This image is of what would be built in 400m x 20m, 15m high trench. The excavated regolith is processed to remove useful stuff, and the spoil makes the roof.

One innovation I've come across that will help all these designs:
https://www.youtube.com/watch?v=aJ4TJ4-kkDw
This invention effectively provides "artificial sunlight". Once this becomes cheaper, we can build dwellings without regard to sunlight, either on Earth or Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 12/10/2018 01:16 pm
With the discussion of mining vehicals and regular washing for maintinance, has anyone revisited the concept of a mineral-oil-sealed waterlock for the vehical bay?
 (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1400300;image)
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Clearly designed for vehicles, not people.

I also incorporated other concepts I have in mind - the up-sloped/stepped design, the "central creek".

This all assumes of course that water is easy to come by, which I think is getting more certain by the day.
'
(big discussion of pros and cons)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 12/10/2018 01:36 pm
With the discussion of mining vehicals and regular washing for maintinance, has anyone revisited the concept of a mineral-oil-sealed waterlock for the vehical bay?
 (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1400300;image)
That post about very deep habitats got me thinking about a no-door airlock.  Do you think it will work?

Clearly designed for vehicles, not people.

I also incorporated other concepts I have in mind - the up-sloped/stepped design, the "central creek".

This all assumes of course that water is easy to come by, which I think is getting more certain by the day.
'
(big discussion of pros and cons)
I think an ice seal will work better, as long as the exit is in a shaded cave.

I also think the water trap should be linked to an underground ice deposit, which will melt inside the lock since pressure and temp are high enough.  This will guarantee that the lock can't go dry.

-----
ABCD: Always Be Counting Down

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/10/2018 01:40 pm
Your images seem to show mostly rotating joints rather than sliding / telescopic ones.  Sliding interfaces (hydraulic cylinders, beam trolleys, mill/lathe ways, etc.) have issues with fluid loss, seal integrity, surface galling, and swarf/dust contamination.

However, if you are going to dig or scoop or pile anything, you need to leverage levers, which means telescoping cylinders a good distance from the rotating pivot point. You aren't going to get much loading if you are limited to powered rotating joints.

So it's either a solved problem by the time you deploy or the whole concept of work vehicles on Mars is show stopper.



But I would like to know how much can one drillhead do. Do they need to exchange the whole drillhead or can they replace single bits? Those drillheads look heavy.

With most of these kinds of things, the main impact part is a swappable bit or blade. Sometimes the part the bit/blade attaches to is also swappable, sometimes it's welded on. That's what it looks like with road-headers, swappable bits, sometimes swappable bases sometimes welded. The bits are crazy hard but wear down like they're wet cardboard.

(I haven't been involved in mining, but I grew up around building sites. I recall the "fun" of weekends spent in the garage replacing the individual blades on a trencher. Worse when replacing chain links. Worse when replacing the trailing cog. Worst of all when replacing the drive cog, pulling out the engine was easier. (A trencher is like a chainsaw had sex with a bull-dozer.))
The roadheader has swappable teeth.  Likely very hard steel. Probably a great pain to change.   I'm hopping we can find a nice sandstone equivalent on Mars, so minimum wear.  Average downtimes for roadheaders in the litterature seems low, so perhaps it's not too much of a problem.

A lot of mining is actually done with explosives, ammonia based if I recall correctly.  This is not a good alternative on Mars, where the chemical preparation of the explosive will always use more energy than mechanical grinding.  And grinding creates natural sand and gravel, that should be useful.

Some images of the colony grid, based on Compressed Earth Blocks with tension rings/loops.  I'm begining to see the point that this might just as well be built in a trench.  Will look into the specifics of the methods soon.  My deadline is still March!  Anybody know the difference in energy between digging and boring?


Take a Starship you don't want to fly anymore and point one of its engines at a piece of ground that you do not want to have rocks or regolith.

A somewhat less insane method is a simple backhoe...

https://www.lectura-specs.com/en/model/construction-machinery/crawler-excavators-liebherr/r-934-c-litronic-1036350 (https://www.lectura-specs.com/en/model/construction-machinery/crawler-excavators-liebherr/r-934-c-litronic-1036350)

So I'm going to go on the absolute worst-case scenario. I'm going to ignore Martian gravity here and crib straight from the product sheet.

150kW x 0.3 load factor = 45kW 162 MJ per hour. Basically an ISS size array for the excavator given Martian daylight. An electric backhoe would be vastly more efficienty than filthy dieselses (we hates them precioussss).
10 seconds per scoop = 360 scoops per hour = 360m^3 per hour (it's a bit quicker than that but buckets aren't always full)
Equals roughly 500kJ per cubic metre or 324MJ per house, unless I've dropped a decimal point here or there.

You will need more energy to smooth, pat and make stable slopes like your excavators typically do on Earth but since you're making a single large excavation it should be much easier. Spray water (?) to stabilise the regolith.

As with the roadheader, though the work is mostly scoop and lift, you need a radiator. Or perhaps an ice sublimator, since you are now on the surface.

If you really really want a nice hole in the ground, a good crater is already excavated, and you just have to smooth out the floor (often filled with regolith like Victoria crater), maybe sinter or concrete it over, add your tunnels, scoop some regolith over the top and voila. Of course you want to make the tunnels able to support themselves with 2-3 metres of regolith, which is about 2 tonne-weight per square metre. Sinter the regolith on top if you feel it's better that way.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 01:51 pm
And here is the second element, a roadheader with four to six dump trucks.  100 tonnes for the roadheader, about 40 to 60 tonnes for the trucks.
Not illustrated here is the battery swapper truck ,that carries batteries in and out more or less continuously to power the roadheader.

The roadheader has a rated output of 350 m3 per hour.  This would allow for the excavation of the volume of a suburban house every 2 hours! The entire volume of the Starship in three.  Of course, the system througput is much lower, one would hope at least 10% of that, so perhaps about one house per day.  Present performance of roadheader is usually lower than 35m3 per hour, but that is the type of ratios the Boring company is trying to improve through automation, batteries and use of locally produced liners.

A battery powered roadheader will run much cooler than a diesel powered one.

Your roadheader will need coolant lines to a surface radiator farm. None of the heat will be removed by convection as it is on Earth. Or removable heat sinks, since you are going with battery swaps.

The question of tires is a good one. Those titanium wire ones are really only for a small rover that doesn't go very far or fast compared to a hard working mine vehicle.
I was hoping the rock might be considered a removable heat sink, as most of the work will be happening to it.  As the drilling head gets hotter it might eventually create evaporation from the surronding rock, if it has, say 10% water content?  Phase change would take up quite a bit of heat.
Radiation would have to provide the rest of the cooling. At 70C with -50 walls and good emissivity I'm getting about 300W/m2. So the road header itself can only radiate a few kW at best, and it has to operate efficiently.
Although the roadheader would have about 300 kW of power, it would be operating on average at about 10% of this, so 30 kW would need to be removed, over an hour that would be 100 000 kJ.  If we can remove 30 tonnes per hour, or 30 000 kg, with 1 kJ/kg Cp,  then the temperature of the rock would need to be raised about 3C to remove 100 000 kJ.  Seems possible.  The road header I'm basing my design on is rated in the Sandvik catalogue at 350 tonnes per hour maximum output so 30 tonnes per hour seems reasonable.



I know that with TBM bits, about 40% of the energy goes into the shattered rock and can be considered removed. The remainder stays with the machine through efficiency losses and also the fact that the bit itself will also heat up from the friction without Maxwell's Demon to shovel the heat away.
An evaporatively cooled head?  Water melted elsewhere from waste heat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/10/2018 02:03 pm
I know that with TBM bits, about 40% of the energy goes into the shattered rock and can be considered removed. The remainder stays with the machine through efficiency losses and also the fact that the bit itself will also heat up from the friction without Maxwell's Demon to shovel the heat away.
An evaporatively cooled head?  Water melted elsewhere from waste heat.

The sublimed water vapour is going to go somewhere though. Possibly build up in the tunnel. Not a showstopper.

Also, on the topic of ice, it's still quite viable as a construction material... stickying this here even though I'm sure this paper has been mentioned before.

https://arxiv.org/ftp/arxiv/papers/1303/1303.5356.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/10/2018 02:20 pm
Not sure about energy, but on Earth, digging is almost always preferred unless:
- The tunnel is very deep - typically more than 10m (or more fora big tunnel)
- You don't want to disturb the surface because it's a City, or Water. 

More important, which can be done with less manual input? Probably both - diggers can be automated (we don't, because operators on Earth are cheap).

I was thinking of something cut and cover.

This image is of what would be built in 400m x 20m, 15m high trench. The excavated regolith is processed to remove useful stuff, and the spoil makes the roof.

One innovation I've come across that will help all these designs:
https://www.youtube.com/watch?v=aJ4TJ4-kkDw
This invention effectively provides "artificial sunlight". Once this becomes cheaper, we can build dwellings without regard to sunlight, either on Earth or Mars.

Digging preferred to tunnelling on Earth. Sure, but on Earth we don't need to worry about air pressure and radiation.

The pretend skylights were mentioned very many pages back in this thread. Great technology. Will surely be used on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 02:23 pm
I know that with TBM bits, about 40% of the energy goes into the shattered rock and can be considered removed. The remainder stays with the machine through efficiency losses and also the fact that the bit itself will also heat up from the friction without Maxwell's Demon to shovel the heat away.
An evaporatively cooled head?  Water melted elsewhere from waste heat.

The sublimed water vapour is going to go somewhere though. Possibly build up in the tunnel. Not a showstopper.

Also, on the topic of ice, it's still quite viable as a construction material... stickying this here even though I'm sure this paper has been mentioned before.

https://arxiv.org/ftp/arxiv/papers/1303/1303.5356.pdf
Fans.  If it’s a gas fans can remove it. Even if it’s very low density gas.  At 2.2 mj/ kg would need 80 kg/hr for 50 KW load.  Would stick to walls but that wouldn’t be a problem.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 03:20 pm
Your images seem to show mostly rotating joints rather than sliding / telescopic ones.  Sliding interfaces (hydraulic cylinders, beam trolleys, mill/lathe ways, etc.) have issues with fluid loss, seal integrity, surface galling, and swarf/dust contamination.

However, if you are going to dig or scoop or pile anything, you need to leverage levers, which means telescoping cylinders a good distance from the rotating pivot point. You aren't going to get much loading if you are limited to powered rotating joints.

So it's either a solved problem by the time you deploy or the whole concept of work vehicles on Mars is show stopper.



But I would like to know how much can one drillhead do. Do they need to exchange the whole drillhead or can they replace single bits? Those drillheads look heavy.

With most of these kinds of things, the main impact part is a swappable bit or blade. Sometimes the part the bit/blade attaches to is also swappable, sometimes it's welded on. That's what it looks like with road-headers, swappable bits, sometimes swappable bases sometimes welded. The bits are crazy hard but wear down like they're wet cardboard.

(I haven't been involved in mining, but I grew up around building sites. I recall the "fun" of weekends spent in the garage replacing the individual blades on a trencher. Worse when replacing chain links. Worse when replacing the trailing cog. Worst of all when replacing the drive cog, pulling out the engine was easier. (A trencher is like a chainsaw had sex with a bull-dozer.))
The roadheader has swappable teeth.  Likely very hard steel. Probably a great pain to change.   I'm hopping we can find a nice sandstone equivalent on Mars, so minimum wear.  Average downtimes for roadheaders in the litterature seems low, so perhaps it's not too much of a problem.

A lot of mining is actually done with explosives, ammonia based if I recall correctly.  This is not a good alternative on Mars, where the chemical preparation of the explosive will always use more energy than mechanical grinding.  And grinding creates natural sand and gravel, that should be useful.

Some images of the colony grid, based on Compressed Earth Blocks with tension rings/loops.  I'm begining to see the point that this might just as well be built in a trench.  Will look into the specifics of the methods soon.  My deadline is still March!  Anybody know the difference in energy between digging and boring?


Take a Starship you don't want to fly anymore and point one of its engines at a piece of ground that you do not want to have rocks or regolith.

A somewhat less insane method is a simple backhoe...

https://www.lectura-specs.com/en/model/construction-machinery/crawler-excavators-liebherr/r-934-c-litronic-1036350 (https://www.lectura-specs.com/en/model/construction-machinery/crawler-excavators-liebherr/r-934-c-litronic-1036350)

So I'm going to go on the absolute worst-case scenario. I'm going to ignore Martian gravity here and crib straight from the product sheet.

150kW x 0.3 load factor = 45kW 162 MJ per hour. Basically an ISS size array for the excavator given Martian daylight. An electric backhoe would be vastly more efficienty than filthy dieselses (we hates them precioussss).
10 seconds per scoop = 360 scoops per hour = 360m^3 per hour (it's a bit quicker than that but buckets aren't always full)
Equals roughly 500kJ per cubic metre or 324MJ per house, unless I've dropped a decimal point here or there.

You will need more energy to smooth, pat and make stable slopes like your excavators typically do on Earth but since you're making a single large excavation it should be much easier. Spray water (?) to stabilise the regolith.

As with the roadheader, though the work is mostly scoop and lift, you need a radiator. Or perhaps an ice sublimator, since you are now on the surface.

If you really really want a nice hole in the ground, a good crater is already excavated, and you just have to smooth out the floor (often filled with regolith like Victoria crater), maybe sinter or concrete it over, add your tunnels, scoop some regolith over the top and voila. Of course you want to make the tunnels able to support themselves with 2-3 metres of regolith, which is about 2 tonne-weight per square metre. Sinter the regolith on top if you feel it's better that way.
You should see that pages and pages of posts about BFS landings  about how using a Starship engine near loose rock is a bad idea.
I worry about blowout of anything that isn’t reinforced. 10t per m2 is not monstrous, but still significant.
Ice domes have their own problems, worse than tunnels IMHO, so I’ll stick to tunnels, or trenches. 
Sealing surfaces is a big cost, as the material must come from Earth for quite a while, or be created from organic materials that are created from CO2 at high energy cost.  Or metals that need to be refined, again for a high energy cost.
I was hoping CEBs might provide adequate sealing, but there are a lot of joints that require some kind of caulking or sealing, again.  ANd the CEBs themselves are porous if not mixed with some cement.
So this leads me to choosing a site with some useful cement precursors, therefore areas with lots of deposits.
There are very deep deposits on Mars, that then have been uncovered by erosion, or latter meteroid impact, and one of these would be my choice. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 12/10/2018 03:36 pm
snip...

"A lot of mining is actually done with explosives, ammonia based if I recall correctly.  This is not a good alternative on Mars, where the chemical preparation of the explosive will always use more energy than mechanical grinding.  And grinding creates natural sand and gravel, that should be useful."
Liquid oxygen and liquid methane can form a miscible solution if some carbon monoxide is present. Such a solution might well be used as an explosive with a little ingenuity and a blasting cap.
https://pubs.acs.org/doi/abs/10.1021/ja01580a062 (https://pubs.acs.org/doi/abs/10.1021/ja01580a062)
But I’m not sure that sand and gravel will be in short supply on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 03:45 pm
snip...

"A lot of mining is actually done with explosives, ammonia based if I recall correctly.  This is not a good alternative on Mars, where the chemical preparation of the explosive will always use more energy than mechanical grinding.  And grinding creates natural sand and gravel, that should be useful."
Liquid oxygen and liquid methane can form a miscible solution if some carbon monoxide is present. Such a solution might well be used as an explosive with a little ingenuity and a blasting cap.
https://pubs.acs.org/doi/abs/10.1021/ja01580a062 (https://pubs.acs.org/doi/abs/10.1021/ja01580a062)
But I’m not sure that sand and gravel will be in short supply on Mars.
Explosives are used in a small scale as well for blasting in hard rock.  It's an art though.  And again, the energy to make the explosives will be larger than the mechanical energy required to break the rock directly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 04:02 pm
Huge energy and resource difference between digging and boring. Digging and boring both require the equivalent energy to excavate a trench and strengthen side walls. But boring also requires some sort of mechanical ceiling support and debris removal through the confines of a tunnel, whereas digging requires a backhoe and dump truck (and often not even the dump truck....).
The joined file shows my question: a trench will require more overall volume due to overexcavation (unless the rock is strong), due to angles of respose for the sand.  I'm thinking 9m x 6m tunnels, so that will require ramps, and large construction vehicles.
Removing debris in the tunnel is a straigtfoward design problem, and trucks can be just as effective as conveyors, if the tunnel is large enough for them to cross.  Probably more, in most cases.  Using some of the material in situ to create blocks might reduce the load somewhat (5-10%?).
It's really just a question of the energy required.  Everything on Mars is a question of the most efficient method, energy wise.  That being said, I'm slowly getting won over by the trench and cover suporters.

I'm adding my Roadheader spreadsheet, that has a trench digger comparision.  My guess at this point is that the roadheader tunnel is about twice the cost of the trench and cover, for the same volume.  As trench and cover uses more volume, the costs are similar, and either one could be chosen, with trench and cover winning out by about... 20 to 50%?
If the tunnels require rock bolts and other added elements then they are even less interesting.

So the main reason to use tunnels would be if the habitat itself (essentially the tunnel lining) can be built for a lower cost in a tunnel, or if we want more than a few meters of covering, as then the handled materials would favor tunnels.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 12/10/2018 04:31 pm
Huge energy and resource difference between digging and boring. Digging and boring both require the equivalent energy to excavate a trench and strengthen side walls. But boring also requires some sort of mechanical ceiling support and debris removal through the confines of a tunnel, whereas digging requires a backhoe and dump truck (and often not even the dump truck....).
The joined file shows my question: a trench will require more overall volume due to overexcavation (unless the rock is strong), due to angles of respose for the sand.  I'm thinking 9m x 6m tunnels, so that will require ramps, and large construction vehicles.
Removing debris in the tunnel is a straigtfoward design problem, and trucks can be just as effective as conveyors, if the tunnel is large enough for them to cross.  Probably more, in most cases.  Using some of the material in situ to create blocks might reduce the load somewhat (5-10%?).
It's really just a question of the energy required.  Everything on Mars is a question of the most efficient method, energy wise.  That being said, I'm slowly getting won over by the trench and cover suporters.
To further facilitate trench and cover, consider building your habitats in the edge of sand dunes. There are many regions where large dunes have accumulated over millions of years. Ideally located near a flat, wind-swept area good for landings.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 04:54 pm
Huge energy and resource difference between digging and boring. Digging and boring both require the equivalent energy to excavate a trench and strengthen side walls. But boring also requires some sort of mechanical ceiling support and debris removal through the confines of a tunnel, whereas digging requires a backhoe and dump truck (and often not even the dump truck....).
The joined file shows my question: a trench will require more overall volume due to overexcavation (unless the rock is strong), due to angles of respose for the sand.  I'm thinking 9m x 6m tunnels, so that will require ramps, and large construction vehicles.
Removing debris in the tunnel is a straigtfoward design problem, and trucks can be just as effective as conveyors, if the tunnel is large enough for them to cross.  Probably more, in most cases.  Using some of the material in situ to create blocks might reduce the load somewhat (5-10%?).
It's really just a question of the energy required.  Everything on Mars is a question of the most efficient method, energy wise.  That being said, I'm slowly getting won over by the trench and cover suporters.
To further facilitate trench and cover, consider building your habitats in the edge of sand dunes. There are many regions where large dunes have accumulated over millions of years. Ideally located near a flat, wind-swept area good for landings.
Yeah, I'm almost convinced to move to trench and cover.  If the colonists want higher density, then can do the tunnels a century from now.  Now, i'd like to reduce conduction as much as possible and tunnels offered a better environment for that aspect; perhaps there is a clever way of piling sand to avoid contact with the colony walls as much as possible, using in situ materials?  Maximum number of voids....
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2018 04:59 pm
Any pumice on Mars?
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 12/10/2018 06:50 pm
I know that with TBM bits, about 40% of the energy goes into the shattered rock and can be considered removed. The remainder stays with the machine through efficiency losses and also the fact that the bit itself will also heat up from the friction without Maxwell's Demon to shovel the heat away.
An evaporatively cooled head?  Water melted elsewhere from waste heat.

The sublimed water vapour is going to go somewhere though. Possibly build up in the tunnel. Not a showstopper.

Also, on the topic of ice, it's still quite viable as a construction material... stickying this here even though I'm sure this paper has been mentioned before.

https://arxiv.org/ftp/arxiv/papers/1303/1303.5356.pdf
Fans.  If it’s a gas fans can remove it. Even if it’s very low density gas.  At 2.2 mj/ kg would need 80 kg/hr for 50 KW load.  Would stick to walls but that wouldn’t be a problem.

Thank you. Fans are my go-to for this discussion as well. Just because the air density is low doesn't mean that car radiators won't work fine for any sort of vehicle. Increase the size of the radiator, the air speed across it, or both.

Mass heat sinks will also work. Store waste heat during the day and blow super-cold night air across a radiator.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/11/2018 04:58 am
A lot of mining is actually done with explosives, ammonia based if I recall correctly.  This is not a good alternative on Mars, where the chemical preparation of the explosive will always use more energy than mechanical grinding.

Hmmm, can you use freezing water as your "explosive"? Drill holes into the Mars-temp rockface, pump in warm water while the holes are still above freezing and plug the holes. Then let the whole thing (ha!) sit overnight and freeze. Cold's free. Expanding water-ice breaks open the rock by morning. Crew come in and clean up the rubble and prepare the next face.



If you really really want a nice hole in the ground, a good crater is already excavated,

It's not the hole, it's the cover. The idea with cut'n'cover is that if you are digging out regolith to cover a surface hab, then why not put the hab in the hole. Halves how much you have to dig.



However, I want to go back to a point I made awhile ago: Your habitats, at least for the first few thousand settlers, won't use a separate technology. Water extraction will be your primary external activity, right from the very first settlers, in order to feed the fuel production in order to make the ships affordable. How you site your habitats will slave off of whatever process you use to get water, just as where you site them does.

The exception is if you can just pump hot water (or some working fluid) down a borehole into a frozen aquifer or glacier and pump melted water back up. Every other method means a type of construction that you will exploit for your habitat/settlement. For eg...

- If you need to mine into an underground frozen aquifer, then you live in the spaces you've excavated.

- If you need to dig up "wet" regolith to process, you site your habs in the trenches you've dug.

- If lava tubes do collect water-ice as I hope, you live in lava tubes.

- If you can dig directly into a lightly covered glacier, you open up near-fantasy scenarios of floating habitats in bubbles of melt-water kept liquid by your waste heat.

(The latter is so far outside of what we picture with Mars colonies, it's hard to include in any Mars discussion, even though such glaciers would be overwhelmingly the best site for a colony.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/11/2018 06:35 am
a trench will require more overall volume due to overexcavation (unless the rock is strong), due to angles of respose for the sand.

You don't let the trench walls slump. The usual method on Earth is to supported trench walls with wooden boards or corrugated metal sheets. For larger/deeper works you start by cutting two thin parallel trenches, line each face with boards/sheets, then pour concrete between the liners, removing the liners once cured. The liners are reused and last decades (**). Those first trenches become the retaining walls of your main trench, you can then safely excavate the space in between the walls. No slump, no slope.

**(Even wooden boards. The concrete seems to soak in and protect them. They virtually end up wood-fibre reinforced concrete slabs. But if you use thin ply, or fibre/plaster board, that is typically not reused. Either left in the hole or dumped after use. I remember when they used asbestos boards for a lot of this. (Amazing stuff. We lost such an amazing material when it turned out to be dangerous.) There's also a method where you pump a clay-slurry into the trench as you are digging, it's liquid enough to not interfere with the trenching but dense enough to prevent trench collapse, allowing unlined trenches. But it's less dense than concrete, so you can pour directly into the slurry, pumping it out as it overfills, into holding tanks for re-use. Never seen that technique in person, but it's impressively simple/clever. Sadly not usable on Mars, though.)

Ideally, this whole process should be linear. Ie, the wall-diggers work ahead of the wall-makers, ahead of the main trench excavation, ahead of the foundation layers, ahead of the hab placement, ahead of the hab utilities connections and other work, ahead of the backfill, in a continuous process as the settlement grows.

I don't know how viable the various proposed "Marscrete"'s will turn out to be. Nor how good regolith blocks might be. Hell, you might be able to directly sinter the walls of the trench as you dig. Or not. But basically you use whatever is easiest to use. It might just be sheets of corrugated iron hammered into the ground and bracing bars as you dig down, pulled out once you've placed the habs, allowed to slump onto the habs, with the excavated material piled over. Move on to the next section. No sintering, no Marscrete, no blocks, no foundations.

Now, i'd like to reduce conduction as much as possible and tunnels offered a better environment for that aspect; perhaps there is a clever way of piling sand to avoid contact with the colony walls as much as possible, using in situ materials?

IMO, you don't want to avoid thermal conduction. The habitats produce waste heat that needs to be gotten rid of. You've got a handy heat-sink around you. Why insulate the habitat and then have to run pipes to a heat-exchange on the surface?

But if you have to have gaps, you can still cut'n'cover. Obviously that's what we do for cut'n'cover tunnels, going back to the very first London Underground. You might enclose a full cut'n'cover arched tunnel made from regolith blocks, with a gap between the habs and the tunnel walls. It's hard to imagine a trench in regolith requiring more energy or complexity than a similar sized tunnel dug into rock. It's hard to imagine a rock tunnel coming within an order of magnitude.



(Contradicting myself: If the processed regolith blocks (or the walls of a rock-mined tunnel) aren't too gas-permeable, you might pressurise the tunnel-trench with raw Mars atmosphere. Doesn't matter if it leaks, as long as the air pumps can keep up and the energy cost of running them isn't too great. The habs can then effectively be unpressurised and just need to be gas-tight, they can be any shape, even rectangular. And you can do pseudo-EVAs into the tunnel with just breathing air tanks or hoses. That easy-of-access means you can put a lot of industrial systems in the tunnel as well; not inside of the habs, but still pressurised (in an inert atmosphere) and protected from the surface.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/11/2018 06:38 am
Just because the air density is low doesn't mean that car radiators won't work fine for any sort of vehicle. Increase the size of the radiator, the air speed across it, or both.

At just a few kmh airflow, conduction to air causes as much heat-loss as radiation. Above that, conduction to air quickly becomes dominant.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/11/2018 07:07 am
The exception is if you can just pump hot water (or some working fluid) down a borehole into a frozen aquifer or glacier and pump melted water back up.
I think this could also be a good way of creating space for underground habitats, which you could control accurately with directed high pressure hot water. Whatever method you use, in ground like that you probably have to be aware of the effect of waste heat on the surrounding soil. IMO the best solution is to build your base already at equilibrium re buoyancy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 12/11/2018 08:41 am
Is it necessary to dig a deep trench? There must be a lot of depressions and craters of all shapes and sizes over vast areas of Mars. Can't a base be built in a small crater or depression and then back filled? I don't think there will be any shortage of gravel, rock fragments, sand and dust on Mars, the surface is covered in it. Just use a bulldozer.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/11/2018 09:20 am
It's really just a question of the energy required.  Everything on Mars is a question of the most efficient method, energy wise.

That is fundamentally wrong, as I see it. Energy use is not the limiting factor on Mars, since there is a renewable energy source (solar) present. The limiting factor is mass brought from Earth. You want to maximise the usefulness of every gramme of material you bring from Earth.

As I see it, scaffolding and bags of cement are very heavy items that could easily be exchanged for more useful, productive material brought from Earth. This is why I think cut-and-cover is a no-go, unless the support structures and cement can be produced exclusively of locally sourced materials. Which technique would be possible? Brick arches with some source of locally-produced cement, I guess: but I wonder if they won't be more difficult to construct than tunnels.

The basic fact of Martian construction is this: Energy is already there. Construction material is already there. What is NOT there is construction equipment.

You want a building strategy which maximises the percentage of construction equipment you bring, to the exclusion of construction material. Energy you either bring (nuclear) or harvest (solar).

So, I think people should be searching for the technique which will deliver maximum habitable volume with the least construction material brought from Earth. With the extreme mass limitation of flying material in from planet Earth you need that mass to be actionable, and not just rebar and cement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/11/2018 10:01 am
[hrInteresting paper on using percussion or gas jets to excavate on the Moon. Earth-moving equipment could therefore be made quite light.

https://www.researchgate.net/publication/268568929_Novel_Approaches_to_Drilling_and_Excavation_on_the_Moon

A bulldozer blade mounted on a lunar rover prototype. Includes all the equations you could want for plugging into a spreadhseet.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130012987.pdf[/hr]

Hmmm, can you use freezing water as your "explosive"? Drill holes into the Mars-temp rockface, pump in warm water while the holes are still above freezing and plug the holes. Then let the whole thing (ha!) sit overnight and freeze. Cold's free. Expanding water-ice breaks open the rock by morning. Crew come in and clean up the rubble and prepare the next face.



Martian sedimentary bedrock seems heavily fractured so it would likely just expand along joints and bedding, and/or just push out the plug... it is pretty soft so just take a pneumatic drill to it.

Quote
If you really really want a nice hole in the ground, a good crater is already excavated,

It's not the hole, it's the cover. The idea with cut'n'cover is that if you are digging out regolith to cover a surface hab, then why not put the hab in the hole. Halves how much you have to dig.



The craters are already filled with dust and regolith, but considering the PITA of getting in and out of the crater... better to cut n cover. The regolith is so thick anyway you just scoop it out. And if you want subsurface ice you'll probably have to dig for it.

Quote
However, I want to go back to a point I made awhile ago: Your habitats, at least for the first few thousand settlers, won't use a separate technology. Water extraction will be your primary external activity, right from the very first settlers, in order to feed the fuel production in order to make the ships affordable. How you site your habitats will slave off of whatever process you use to get water, just as where you site them does.

The exception is if you can just pump hot water (or some working fluid) down a borehole into a frozen aquifer or glacier and pump melted water back up. Every other method means a type of construction that you will exploit for your habitat/settlement. For eg...

- If you need to mine into an underground frozen aquifer, then you live in the spaces you've excavated.

Easier to extract frozen underground aquifer water by heating the borehole.

Quote
- If you need to dig up "wet" regolith to process, you site your habs in the trenches you've dug.

- If lava tubes do collect water-ice as I hope, you live in lava tubes.

- If you can dig directly into a lightly covered glacier, you open up near-fantasy scenarios of floating habitats in bubbles of melt-water kept liquid by your waste heat.

(The latter is so far outside of what we picture with Mars colonies, it's hard to include in any Mars discussion, even though such glaciers would be overwhelmingly the best site for a colony.)

Agree with your points, but Phoenix got buried under 30cm of CO2 ice, which is believed to have snapped off one of its solar panels...

In the game Offworld Trading Company the colonies do actually start off at the poles and only progress further south once the technology to mine aquifers is developed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: alexterrell on 12/11/2018 11:03 am

The joined file shows my question: a trench will require more overall volume due to overexcavation (unless the rock is strong), due to angles of respose for the sand.  I'm thinking 9m x 6m tunnels, so that will require ramps, and large construction vehicles.
I think the cost of a trench-solution will increase by a small amount with increased size, especially as the amount of top cover required stays roughly constant. So for large buildings, it will beat tunneling, for small ones, not sure. Hence why I went for a 20m wide, 15m high structure.

The trench solution also needs more steel work. It should support the roof in event of a pressure loss. But the structure is then pretty straight forward, and we know a lot about how to build with steel.

So I think it will win hands down for later, larger developments.

Tunnels may be attractive earlier on, but there they compete with inflatable domes. I attach a 30m dome sketch, which could be delivered in a single mission and inflated and packed with regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 12/11/2018 11:06 am
...
...
That is fundamentally wrong, as I see it. Energy use is not the limiting factor on Mars, since there is a renewable energy source (solar) present. The limiting factor is mass brought from Earth. You want to maximise the usefulness of every gramme of material you bring from Earth.

As I see it, scaffolding and bags of cement are very heavy items that could easily be exchanged for more useful, productive material brought from Earth. This is why I think cut-and-cover is a no-go, unless the support structures and cement can be produced exclusively of locally sourced materials. Which technique would be possible? Brick arches with some source of locally-produced cement, I guess: but I wonder if they won't be more difficult to construct than tunnels.

The basic fact of Martian construction is this: Energy is already there. Construction material is already there. What is NOT there is construction equipment.

You want a building strategy which maximises the percentage of construction equipment you bring, to the exclusion of construction material. Energy you either bring (nuclear) or harvest (solar).

So, I think people should be searching for the technique which will deliver maximum habitable volume with the least construction material brought from Earth. With the extreme mass limitation of flying material in from planet Earth you need that mass to be actionable, and not just rebar and cement.
I agree that materials from Earth are the first limiting factor and energy is second. You may be interested in an article from 2014 that spells out such an approach. It exploits naturally occurring rock formations and involves cutting rock into blocks. No heavy machines or large equipment, just diamond-tipped chain saws and rock cutters.
http://themarspioneer.com/PioneerHouse.html

Edit: 2015 2014
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/11/2018 11:59 am
A lot of mining is actually done with explosives, ammonia based if I recall correctly.  This is not a good alternative on Mars, where the chemical preparation of the explosive will always use more energy than mechanical grinding.

Hmmm, can you use freezing water as your "explosive"? Drill holes into the Mars-temp rockface, pump in warm water while the holes are still above freezing and plug the holes. Then let the whole thing (ha!) sit overnight and freeze. Cold's free. Expanding water-ice breaks open the rock by morning. Crew come in and clean up the rubble and prepare the next face.




If you really really want a nice hole in the ground, a good crater is already excavated,

It's not the hole, it's the cover. The idea with cut'n'cover is that if you are digging out regolith to cover a surface hab, then why not put the hab in the hole. Halves how much you have to dig.



However, I want to go back to a point I made awhile ago: Your habitats, at least for the first few thousand settlers, won't use a separate technology. Water extraction will be your primary external activity, right from the very first settlers, in order to feed the fuel production in order to make the ships affordable. How you site your habitats will slave off of whatever process you use to get water, just as where you site them does.

The exception is if you can just pump hot water (or some working fluid) down a borehole into a frozen aquifer or glacier and pump melted water back up. Every other method means a type of construction that you will exploit for your habitat/settlement. For eg...

- If you need to mine into an underground frozen aquifer, then you live in the spaces you've excavated.

- If you need to dig up "wet" regolith to process, you site your habs in the trenches you've dug.

- If lava tubes do collect water-ice as I hope, you live in lava tubes.

- If you can dig directly into a lightly covered glacier, you open up near-fantasy scenarios of floating habitats in bubbles of melt-water kept liquid by your waste heat.

(The latter is so far outside of what we picture with Mars colonies, it's hard to include in any Mars discussion, even though such glaciers would be overwhelmingly the best site for a colony.)
If the icecrete idea is correct, you might just end up with an even stronger wall, that you have just reinforced with a strong binder.  Melting the ice takes more energy than breaking the surface, I believe.

Anything kelp going by waste heat is subject to the risk that the waste heat is not available for a while.  This was a problem with many energy recovery scenarios dreamed up over the years for Northern communities:  Most mines and plants deliver lots of waste heat, but they also have down time.  So a village heated by a factory needed a back-up system for when the factory was shut down, and energy is so cheap the cost of the backup plant was always too high.
An exception is Northern mines that are off the grid are sometimes heated by waste heat from the electrical generators. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/11/2018 12:12 pm
It's really just a question of the energy required.  Everything on Mars is a question of the most efficient method, energy wise.

That is fundamentally wrong, as I see it. Energy use is not the limiting factor on Mars, since there is a renewable energy source (solar) present. The limiting factor is mass brought from Earth. You want to maximise the usefulness of every gramme of material you bring from Earth.

As I see it, scaffolding and bags of cement are very heavy items that could easily be exchanged for more useful, productive material brought from Earth. This is why I think cut-and-cover is a no-go, unless the support structures and cement can be produced exclusively of locally sourced materials. Which technique would be possible? Brick arches with some source of locally-produced cement, I guess: but I wonder if they won't be more difficult to construct than tunnels.

The basic fact of Martian construction is this: Energy is already there. Construction material is already there. What is NOT there is construction equipment.

You want a building strategy which maximises the percentage of construction equipment you bring, to the exclusion of construction material. Energy you either bring (nuclear) or harvest (solar).

So, I think people should be searching for the technique which will deliver maximum habitable volume with the least construction material brought from Earth. With the extreme mass limitation of flying material in from planet Earth you need that mass to be actionable, and not just rebar and cement.
Hum.  Energy is in fact brought to Mars as infrastructure, solar panels or reactors.  Equipement cannot work without energy, so you could bring any amount of equipment, it cannot work without the infrastructure.
Without the panels, the solar energy is unusable.  So the main limiting factor is the mass of the solar panels, the cost of the energy infrastructure. 
And as far as equipment goes, if it needs to be application specific and every machine requires huge investments to design, then the colony is probably research limited, cost of development will outweight all other costs.
But anyway you're right, my grand idea was incorrect :-)  In my own spreadsheet, equipment costs outweighs enegy by a factor of two to one, and this is for lightly modified equipement.  The equipement cost is 50% equipment, 50% transportation at 500$/kg.  Call it a mix, I guess.


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/11/2018 12:22 pm
I know that with TBM bits, about 40% of the energy goes into the shattered rock and can be considered removed. The remainder stays with the machine through efficiency losses and also the fact that the bit itself will also heat up from the friction without Maxwell's Demon to shovel the heat away.
An evaporatively cooled head?  Water melted elsewhere from waste heat.

The sublimed water vapour is going to go somewhere though. Possibly build up in the tunnel. Not a showstopper.

Also, on the topic of ice, it's still quite viable as a construction material... stickying this here even though I'm sure this paper has been mentioned before.

https://arxiv.org/ftp/arxiv/papers/1303/1303.5356.pdf
Fans.  If it’s a gas fans can remove it. Even if it’s very low density gas.  At 2.2 mj/ kg would need 80 kg/hr for 50 KW load.  Would stick to walls but that wouldn’t be a problem.

Thank you. Fans are my go-to for this discussion as well. Just because the air density is low doesn't mean that car radiators won't work fine for any sort of vehicle. Increase the size of the radiator, the air speed across it, or both.

Mass heat sinks will also work. Store waste heat during the day and blow super-cold night air across a radiator.
A small spreadsheet for cooling using martian atmosphere.  The main unknown ir air velocity that is tolerable in the tunnel, and the heat transfer mechanism within the tunnel head that transfers energy from the equipment to the air. See the air cooling tab.  The air flow is for a large 90m2 tunnel.  The 500 kW is probably much too high.

The Martian air will need to move extremely quickly through the radiator to be effective, and probably have a very large surface radiator.  Dust clogging may be a problem on Mars, if the air passages are too small.  Possible a very high number of fins per inch?
There is also the question that the extremely low Martian air pressure doesn't have as much pressure drop capacity as air on Earth.  Would need to look at the pressure drop under heavily turbulent flow.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/11/2018 12:26 pm
[hrInteresting paper on using percussion or gas jets to excavate on the Moon. Earth-moving equipment could therefore be made quite light.

https://www.researchgate.net/publication/268568929_Novel_Approaches_to_Drilling_and_Excavation_on_the_Moon

A bulldozer blade mounted on a lunar rover prototype. Includes all the equations you could want for plugging into a spreadhseet.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130012987.pdf[/hr]

Hmmm, can you use freezing water as your "explosive"? Drill holes into the Mars-temp rockface, pump in warm water while the holes are still above freezing and plug the holes. Then let the whole thing (ha!) sit overnight and freeze. Cold's free. Expanding water-ice breaks open the rock by morning. Crew come in and clean up the rubble and prepare the next face.



Martian sedimentary bedrock seems heavily fractured so it would likely just expand along joints and bedding, and/or just push out the plug... it is pretty soft so just take a pneumatic drill to it.

Quote
If you really really want a nice hole in the ground, a good crater is already excavated,

It's not the hole, it's the cover. The idea with cut'n'cover is that if you are digging out regolith to cover a surface hab, then why not put the hab in the hole. Halves how much you have to dig.



The craters are already filled with dust and regolith, but considering the PITA of getting in and out of the crater... better to cut n cover. The regolith is so thick anyway you just scoop it out. And if you want subsurface ice you'll probably have to dig for it.

Quote
However, I want to go back to a point I made awhile ago: Your habitats, at least for the first few thousand settlers, won't use a separate technology. Water extraction will be your primary external activity, right from the very first settlers, in order to feed the fuel production in order to make the ships affordable. How you site your habitats will slave off of whatever process you use to get water, just as where you site them does.

The exception is if you can just pump hot water (or some working fluid) down a borehole into a frozen aquifer or glacier and pump melted water back up. Every other method means a type of construction that you will exploit for your habitat/settlement. For eg...

- If you need to mine into an underground frozen aquifer, then you live in the spaces you've excavated.

Easier to extract frozen underground aquifer water by heating the borehole.

Quote
- If you need to dig up "wet" regolith to process, you site your habs in the trenches you've dug.

- If lava tubes do collect water-ice as I hope, you live in lava tubes.

- If you can dig directly into a lightly covered glacier, you open up near-fantasy scenarios of floating habitats in bubbles of melt-water kept liquid by your waste heat.

(The latter is so far outside of what we picture with Mars colonies, it's hard to include in any Mars discussion, even though such glaciers would be overwhelmingly the best site for a colony.)

Agree with your points, but Phoenix got buried under 30cm of CO2 ice, which is believed to have snapped off one of its solar panels...

In the game Offworld Trading Company the colonies do actually start off at the poles and only progress further south once the technology to mine aquifers is developed.
Thanks for the references. 
How about we dig tunnels, for ice, perhaps,  then use the tunnels to installs habs.  On the surface, we use the rock extracted from the mine to cover more habitats?  A mix of both solutions?
Seems energy/ressources efficient.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/11/2018 01:34 pm
Thanks for the references. 
How about we dig tunnels, for ice, perhaps,  then use the tunnels to installs habs.  On the surface, we use the rock extracted from the mine to cover more habitats?  A mix of both solutions?
Seems energy/ressources efficient.


My pleasure.

Here are some more references. In the first, they examine water well extraction (drilling, melting the ice and extracting it). For some reason not specified, they essentially abandon the idea of mining solid ice blocks.

https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf

In another paper, it is noted that ice blocks are too strong to remove at with a backhoe at Martian temperatures. In fact, the strength of ice on Mars is equivalent to that of basalt (!). A roadheader would struggle with it. So for large quantities of Martian ice, they need to be drilled and blasted out. The author notes that explosives are a Bad Idea on Mars due to the low gravity making the debris fly much, much further. You only want to do this if you are ice mining for a colony.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

So basically, ice on Mars is as strong as rock.

Another paper indicates that permafrost at 20-30% ice is quite hard but still possible to excavate, especially if cut with a saw to 10cm first. Below 15% the permafrost is not cohesive and can be excavated with a backhoe.

https://arc.aiaa.org/doi/abs/10.2514/6.2016-0227
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/11/2018 01:49 pm
...
...
That is fundamentally wrong, as I see it. Energy use is not the limiting factor on Mars, since there is a renewable energy source (solar) present. The limiting factor is mass brought from Earth. You want to maximise the usefulness of every gramme of material you bring from Earth.

As I see it, scaffolding and bags of cement are very heavy items that could easily be exchanged for more useful, productive material brought from Earth. This is why I think cut-and-cover is a no-go, unless the support structures and cement can be produced exclusively of locally sourced materials. Which technique would be possible? Brick arches with some source of locally-produced cement, I guess: but I wonder if they won't be more difficult to construct than tunnels.

The basic fact of Martian construction is this: Energy is already there. Construction material is already there. What is NOT there is construction equipment.

You want a building strategy which maximises the percentage of construction equipment you bring, to the exclusion of construction material. Energy you either bring (nuclear) or harvest (solar).

So, I think people should be searching for the technique which will deliver maximum habitable volume with the least construction material brought from Earth. With the extreme mass limitation of flying material in from planet Earth you need that mass to be actionable, and not just rebar and cement.
I agree that materials from Earth are the first limiting factor and energy is second. You may be interested in an article from 2014 that spells out such an approach. It exploits naturally occurring rock formations and involves cutting rock into blocks. No heavy machines or large equipment, just diamond-tipped chain saws and rock cutters.
http://themarspioneer.com/PioneerHouse.html

Thanks, very interesting paper. I imagine something like this "zipper" block-building technique...
https://youtu.be/7ns5UBd0gls

No cement needed. However, the technique on Mars would require ISRU blocks and whether they can be made easily is a big unknown.

Tunnel excavation is more of a known challenge. If it results in useable blocks it could perhaps be combined with habitat building as Lamontagne suggest and as the above video shows.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 12/11/2018 02:26 pm
Zipper truck construction looks like a good idea.
However, note that this technique depends on gravity to hold the blocks in place and any force from above merely compresses the blocks together. On this forum it is well established that on Mars  the internal pressure of a habitable structure will require substantial tensile strength to hold it together. Even 3 m of regolith cover may not enough. So an added requirement is some form of adhesive between blocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/11/2018 02:52 pm
...Why is why my preferred method will always be tunnelling in bedrock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/13/2018 01:46 am
Thanks for the references. 
How about we dig tunnels, for ice, perhaps,  then use the tunnels to installs habs.  On the surface, we use the rock extracted from the mine to cover more habitats?  A mix of both solutions?
Seems energy/ressources efficient.


My pleasure.

Here are some more references. In the first, they examine water well extraction (drilling, melting the ice and extracting it). For some reason not specified, they essentially abandon the idea of mining solid ice blocks.

https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf

In another paper, it is noted that ice blocks are too strong to remove at with a backhoe at Martian temperatures. In fact, the strength of ice on Mars is equivalent to that of basalt (!). A roadheader would struggle with it. So for large quantities of Martian ice, they need to be drilled and blasted out. The author notes that explosives are a Bad Idea on Mars due to the low gravity making the debris fly much, much further. You only want to do this if you are ice mining for a colony.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

So basically, ice on Mars is as strong as rock.

Another paper indicates that permafrost at 20-30% ice is quite hard but still possible to excavate, especially if cut with a saw to 10cm first. Below 15% the permafrost is not cohesive and can be excavated with a backhoe.

https://arc.aiaa.org/doi/abs/10.2514/6.2016-0227

My little Mars place.  A small 2km crater, filled with sediment, and then emptied by runoff.
The base is both within the cliff by boring and under the tailings from the tunnels.
The excavated rock has something like15% water content, most of it as real water, not tied in with the rock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/13/2018 11:47 am
can you use freezing water as your "explosive"? [...] Expanding water-ice breaks open the rock by morning.
If the icecrete idea is correct, you might just end up with an even stronger wall, that you have just reinforced with a strong binder.

Water expands as it freezes, exerting a surprising amount of force. It's an erosion mechanism in rocks on Earth. I'm just wondering if it can be used in place of explosives on Mars, since the cold is essentially free.

- If you can dig directly into a lightly covered glacier, you open up near-fantasy scenarios of floating habitats in bubbles of melt-water kept liquid by your waste heat.
Anything kelp going by waste heat is subject to the risk that the waste heat is not available for a while.

The waste heat comes from people living. There's no risk, melting the bubble isn't some vital purpose, rather the glacier is serving as a heat-sink for the habitat (and its industries, and possibly even a nuclear reactor if that's an option over solar.) The bubble of water is just... amusing.

How about we dig tunnels, for ice, perhaps,  then use the tunnels to installs habs.  On the surface, we use the rock extracted from the mine to cover more habitats?  A mix of both solutions? Seems energy/ressources efficient.

That was option 1 on my "water drives everything else" list. If you have to mine water out of an aquifer, you live in the holes.



In fact, the strength of ice on Mars is equivalent to that of basalt (!).

You have to be careful with "strength" claims. That was "Unconfined Compressive Strength" only. Note that a wide auger worked easily on permafrost too hard to pick into. No tensile strength. (With minimal wear on the auger. Try that on basalt.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/13/2018 12:06 pm
On this forum it is well established that on Mars  the internal pressure of a habitable structure will require substantial tensile strength to hold it together. Even 3 m of regolith cover may not enough. So an added requirement is some form of adhesive between blocks.

I doubt adhering the blocks would be enough to contain that much pressure. Bricks are good under compression, terrible under tension.

Aside: Using just mass to counter atmospheric pressure seems excessive unless you have another reason to bury yourself that deep. 1atm is 10tonnes/m². Loose regolith masses around 1 tonne/m². Rock 2-3 tonnes/m². Bricks are typically 2t/m². And, of course, 0.38g on Mars. So to hold 10t/m², you need about 13m depth of bricks. Or about 25m of regolith over a brick arch.

That's why I think you'll need to make pressure vessels, no matter where or how you site the settlement. Which means coming up with a strong ISRU material, which lends itself to extruded basalt fibre wrapped compressive structures. (Higher melt energy than fibre-glass, but in every other way much easier to make.) Which gets us back to energy costs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/13/2018 12:23 pm
Thanks for the references. 
How about we dig tunnels, for ice, perhaps,  then use the tunnels to installs habs.  On the surface, we use the rock extracted from the mine to cover more habitats?  A mix of both solutions?
Seems energy/ressources efficient.


My pleasure.

Here are some more references. In the first, they examine water well extraction (drilling, melting the ice and extracting it). For some reason not specified, they essentially abandon the idea of mining solid ice blocks.

https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf

In another paper, it is noted that ice blocks are too strong to remove at with a backhoe at Martian temperatures. In fact, the strength of ice on Mars is equivalent to that of basalt (!). A roadheader would struggle with it. So for large quantities of Martian ice, they need to be drilled and blasted out. The author notes that explosives are a Bad Idea on Mars due to the low gravity making the debris fly much, much further. You only want to do this if you are ice mining for a colony.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

So basically, ice on Mars is as strong as rock.

Another paper indicates that permafrost at 20-30% ice is quite hard but still possible to excavate, especially if cut with a saw to 10cm first. Below 15% the permafrost is not cohesive and can be excavated with a backhoe.

https://arc.aiaa.org/doi/abs/10.2514/6.2016-0227

My little Mars place.  A small 2km crater, filled with sediment, and then emptied by runoff.
The base is both within the cliff by boring and under the tailings from the tunnels.
The excavated rock has something like15% water content, most of it as real water, not tied in with the rock.


You might like this then:

Multi-Robot Hillside Excavation Strategies for Mars Settlement Construction (https://ttu-ir.tdl.org/bitstream/handle/2346/73023/ICES_2017_227.pdf)

Crater walls are essentiall loose rock and Earth, so you would rather want to burrow into the uplifted lip from the other side, and then drill your tunnels through the circumference.

In fact, the strength of ice on Mars is equivalent to that of basalt (!).

You have to be careful with "strength" claims. That was "Unconfined Compressive Strength" only. Note that a wide auger worked easily on permafrost too hard to pick into. No tensile strength. (With minimal wear on the auger. Try that on basalt.)

Well, rock has pretty poor tensile strength anyway so mostly the ice structures would be in compression. Some of the papers I've seen go for the simplest 3-point arch construction because all locally available materials are much better in compression.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Norm38 on 12/13/2018 12:39 pm
I vote we send the Swedes.  Looks like they've already got it all figured out.

https://www.thousandwonders.net/R%C3%A5dhuset+Metro+Station
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 12/13/2018 12:55 pm


Here are some more references. In the first, they examine water well extraction (drilling, melting the ice and extracting it). For some reason not specified, they essentially abandon the idea of mining solid ice blocks.

https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf

In another paper, it is noted that ice blocks are too strong to remove at with a backhoe at Martian temperatures. In fact, the strength of ice on Mars is equivalent to that of basalt (!). A roadheader would struggle with it. So for large quantities of Martian ice, they need to be drilled and blasted out. The author notes that explosives are a Bad Idea on Mars due to the low gravity making the debris fly much, much further. You only want to do this if you are ice mining for a colony.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

So basically, ice on Mars is as strong as rock.

Another paper indicates that permafrost at 20-30% ice is quite hard but still possible to excavate, especially if cut with a saw to 10cm first. Below 15% the permafrost is not cohesive and can be excavated with a backhoe.

https://arc.aiaa.org/doi/abs/10.2514/6.2016-0227

My little Mars place.  A small 2km crater, filled with sediment, and then emptied by runoff.
The base is both within the cliff by boring and under the tailings from the tunnels.
The excavated rock has something like15% water content, most of it as real water, not tied in with the rock.
[/quote]

So your site is somewhere very much toward the poles for that much water to be found in the rocks.  My issue with such locations is solar power is infeasible in the long winters. Days are too short to non-existent.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 12/13/2018 12:57 pm
Not sure about energy, but on Earth, digging is almost always preferred unless:
- The tunnel is very deep - typically more than 10m (or more fora big tunnel)
- You don't want to disturb the surface because it's a City, or Water. 

More important, which can be done with less manual input? Probably both - diggers can be automated (we don't, because operators on Earth are cheap).

I was thinking of something cut and cover.

This image is of what would be built in 400m x 20m, 15m high trench. The excavated regolith is processed to remove useful stuff, and the spoil makes the roof.

One innovation I've come across that will help all these designs:
https://www.youtube.com/watch?v=aJ4TJ4-kkDw
This invention effectively provides "artificial sunlight". Once this becomes cheaper, we can build dwellings without regard to sunlight, either on Earth or Mars.

Those CoeLux lights are nice.   I found a spec sheet.  They consume around 300W to to light an area of 20m2, which doesn't seem too bad for 'natural' light? 

The 1700 x 850 mm skylight is 3759 x 2274 x 966 mm unit.  It's not clear how they're assembled.  If they can only be shipped as a unit makes it quite a luxury item. 

http://cdn.shopify.com/s/files/1/1046/0812/files/CoeLux__Datasheets_UL_1.pdf?13310844782056675942
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/13/2018 03:57 pm


Here are some more references. In the first, they examine water well extraction (drilling, melting the ice and extracting it). For some reason not specified, they essentially abandon the idea of mining solid ice blocks.

https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf

In another paper, it is noted that ice blocks are too strong to remove at with a backhoe at Martian temperatures. In fact, the strength of ice on Mars is equivalent to that of basalt (!). A roadheader would struggle with it. So for large quantities of Martian ice, they need to be drilled and blasted out. The author notes that explosives are a Bad Idea on Mars due to the low gravity making the debris fly much, much further. You only want to do this if you are ice mining for a colony.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

So basically, ice on Mars is as strong as rock.

Another paper indicates that permafrost at 20-30% ice is quite hard but still possible to excavate, especially if cut with a saw to 10cm first. Below 15% the permafrost is not cohesive and can be excavated with a backhoe.

https://arc.aiaa.org/doi/abs/10.2514/6.2016-0227

My little Mars place.  A small 2km crater, filled with sediment, and then emptied by runoff.
The base is both within the cliff by boring and under the tailings from the tunnels.
The excavated rock has something like15% water content, most of it as real water, not tied in with the rock.

So your site is somewhere very much toward the poles for that much water to be found in the rocks.  My issue with such locations is solar power is infeasible in the long winters. Days are too short to non-existent.
[/quote]
Nope, sited at or near the equator, based on the red areas of this map, that indicate water content that can reach 15% in certain areas.
Ref https://www.nasa.gov/vision/universe/solarsystem/new_maps_mars_water.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/13/2018 04:02 pm
Not sure about energy, but on Earth, digging is almost always preferred unless:
- The tunnel is very deep - typically more than 10m (or more fora big tunnel)
- You don't want to disturb the surface because it's a City, or Water. 

More important, which can be done with less manual input? Probably both - diggers can be automated (we don't, because operators on Earth are cheap).

I was thinking of something cut and cover.

This image is of what would be built in 400m x 20m, 15m high trench. The excavated regolith is processed to remove useful stuff, and the spoil makes the roof.

One innovation I've come across that will help all these designs:
https://www.youtube.com/watch?v=aJ4TJ4-kkDw
This invention effectively provides "artificial sunlight". Once this becomes cheaper, we can build dwellings without regard to sunlight, either on Earth or Mars.

Those CoeLux lights are nice.   I found a spec sheet.  They consume around 300W to to light an area of 20m2, which doesn't seem too bad for 'natural' light? 

The 1700 x 850 mm skylight is 3759 x 2274 x 966 mm unit.  It's not clear how they're assembled.  If they can only be shipped as a unit makes it quite a luxury item. 

http://cdn.shopify.com/s/files/1/1046/0812/files/CoeLux__Datasheets_UL_1.pdf?13310844782056675942
Natural light is anything up to 1000 W/m2, so this is an illusion.  I think te effect is great, but probably wouldn't be all that good for plant growth.  15 W/m2 is standard office lighting levels.
Grow rooms in interior plant production are about 500W/m2 when the lights are on.  Quite blinding and uncomfortable, actually.
Title: Re: Envisioning Amazing Martian Habitats
Post by: glennfish on 12/13/2018 07:27 pm


I would say, go back to the basics.  Of course, it works better at the poles, but if you can make bricks, you really don't need sophisticated technologies.

see:  https://www.youtube.com/watch?v=7jfWm2jTFf4
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/13/2018 07:36 pm
Igloos rely on compressive strength though. On mars you would need 30 meters thickness of ice just to balance earth sea-level pressure.

The igloo structure would probably be good for domed habitats deep underground though. In that case you probably don't want to use ice due to the contained heat. Underground domed habitats would be nice though, especially if you could figure out some way to project a sky onto them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/13/2018 07:55 pm
Install a projection or display membrane ceiling

https://youtu.be/EEq_2dq4OyM
Title: Re: Envisioning Amazing Martian Habitats
Post by: glennfish on 12/13/2018 08:06 pm
Igloos rely on compressive strength though. On mars you would need 30 meters thickness of ice just to balance earth sea-level pressure.

The igloo structure would probably be good for domed habitats deep underground though. In that case you probably don't want to use ice due to the contained heat. Underground domed habitats would be nice though, especially if you could figure out some way to project a sky onto them.

Actually, I like the construction technique.  Doesn't have to be ice.  Airtight bricks, say foamed concrete, with an appropriate bonding agent.  You should watch the video, the technique is ultra simple.  As you watch it, remember you can work foamed concrete with a wood saw.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 12/13/2018 08:35 pm
Not sure about energy, but on Earth, digging is almost always preferred unless:
- The tunnel is very deep - typically more than 10m (or more fora big tunnel)
- You don't want to disturb the surface because it's a City, or Water. 

More important, which can be done with less manual input? Probably both - diggers can be automated (we don't, because operators on Earth are cheap).

I was thinking of something cut and cover.

This image is of what would be built in 400m x 20m, 15m high trench. The excavated regolith is processed to remove useful stuff, and the spoil makes the roof.

One innovation I've come across that will help all these designs:
https://www.youtube.com/watch?v=aJ4TJ4-kkDw
This invention effectively provides "artificial sunlight". Once this becomes cheaper, we can build dwellings without regard to sunlight, either on Earth or Mars.

Those CoeLux lights are nice.   I found a spec sheet.  They consume around 300W to to light an area of 20m2, which doesn't seem too bad for 'natural' light? 

The 1700 x 850 mm skylight is 3759 x 2274 x 966 mm unit.  It's not clear how they're assembled.  If they can only be shipped as a unit makes it quite a luxury item. 

http://cdn.shopify.com/s/files/1/1046/0812/files/CoeLux__Datasheets_UL_1.pdf?13310844782056675942
Natural light is anything up to 1000 W/m2, so this is an illusion.  I think te effect is great, but probably wouldn't be all that good for plant growth.  15 W/m2 is standard office lighting levels.
Grow rooms in interior plant production are about 500W/m2 when the lights are on.  Quite blinding and uncomfortable, actually.

For plant growth / vertical farming it's more energy efficient to use purple LEDs. I wasn't suggesting coelux for that.  It should help with the well-being of the humans though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/14/2018 01:18 am
Install a projection or display membrane ceiling

https://www.youtube.com/watch?v=EEq_2dq4OyM
Done.  Doing the whole colony ceiling would be too heavy, but a number of these would be cool.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/14/2018 01:30 am
Igloos rely on compressive strength though. On mars you would need 30 meters thickness of ice just to balance earth sea-level pressure.

The igloo structure would probably be good for domed habitats deep underground though. In that case you probably don't want to use ice due to the contained heat. Underground domed habitats would be nice though, especially if you could figure out some way to project a sky onto them.

Actually, I like the construction technique.  Doesn't have to be ice.  Airtight bricks, say foamed concrete, with an appropriate bonding agent.  You should watch the video, the technique is ultra simple.  As you watch it, remember you can work foamed concrete with a wood saw.
I think compressed earth blocks might be just as simple, require less energy and offer higher strength and better radiation protection.  But a layer of this would replace styrofoam nicely, and require no organics.  How does this compare to fibreglass insulation though?.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/14/2018 01:32 am
Not sure about energy, but on Earth, digging is almost always preferred unless:
- The tunnel is very deep - typically more than 10m (or more fora big tunnel)
- You don't want to disturb the surface because it's a City, or Water. 

More important, which can be done with less manual input? Probably both - diggers can be automated (we don't, because operators on Earth are cheap).

I was thinking of something cut and cover.

This image is of what would be built in 400m x 20m, 15m high trench. The excavated regolith is processed to remove useful stuff, and the spoil makes the roof.

One innovation I've come across that will help all these designs:
https://www.youtube.com/watch?v=aJ4TJ4-kkDw
This invention effectively provides "artificial sunlight". Once this becomes cheaper, we can build dwellings without regard to sunlight, either on Earth or Mars.

Those CoeLux lights are nice.   I found a spec sheet.  They consume around 300W to to light an area of 20m2, which doesn't seem too bad for 'natural' light? 

The 1700 x 850 mm skylight is 3759 x 2274 x 966 mm unit.  It's not clear how they're assembled.  If they can only be shipped as a unit makes it quite a luxury item. 

http://cdn.shopify.com/s/files/1/1046/0812/files/CoeLux__Datasheets_UL_1.pdf?13310844782056675942
Natural light is anything up to 1000 W/m2, so this is an illusion.  I think te effect is great, but probably wouldn't be all that good for plant growth.  15 W/m2 is standard office lighting levels.
Grow rooms in interior plant production are about 500W/m2 when the lights are on.  Quite blinding and uncomfortable, actually.

For plant growth / vertical farming it's more energy efficient to use purple LEDs. I wasn't suggesting coelux for that.  It should help with the well-being of the humans though.
How high can vertical farm elements be stacked?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/14/2018 07:20 am
Those CoeLux lights are nice. [...] They consume around 300W to to light an area of 20m2, which doesn't seem too bad for 'natural' light?
For plant growth / vertical farming it's more energy efficient to use purple LEDs. I wasn't suggesting coelux for that.  It should help with the well-being of the humans though.

Actually, 15W/m2 is too low for humans too. You need exposure to brighter lights for healthy eye development. And there are issues associated with dim light and depression (beyond the vitamin D connection.)

They give a nice ambience. That's all.

(Also 15W/m2 is the power consumption, unless they've discovered 100% efficient lights, I'm assuming the actual watts of light energy is lower. But the figure gives us a ceiling. No pun intended.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/14/2018 07:21 am
Igloos rely on compressive strength though. On mars you would need 30 meters thickness of ice just to balance earth sea-level pressure.
Actually, I like the construction technique.  Doesn't have to be ice.  Airtight bricks, say foamed concrete, with an appropriate bonding agent.  You should watch the video, the technique is ultra simple.  As you watch it, remember you can work foamed concrete with a wood saw.

You missed his point. On Mars you have the biggest forces inside, air pressure, pushing up and outwards. Igloos, arches, domes, are all intended for the force to be down and inward. They don't work as pressure vessels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/14/2018 07:22 am
How high can vertical farm elements be stacked?

Can you elaborate? "Elements"?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 12/14/2018 07:43 am
Not sure about energy, but on Earth, digging is almost always preferred unless:
- The tunnel is very deep - typically more than 10m (or more fora big tunnel)
- You don't want to disturb the surface because it's a City, or Water. 

More important, which can be done with less manual input? Probably both - diggers can be automated (we don't, because operators on Earth are cheap).

I was thinking of something cut and cover.

This image is of what would be built in 400m x 20m, 15m high trench. The excavated regolith is processed to remove useful stuff, and the spoil makes the roof.

One innovation I've come across that will help all these designs:
https://www.youtube.com/watch?v=aJ4TJ4-kkDw
This invention effectively provides "artificial sunlight". Once this becomes cheaper, we can build dwellings without regard to sunlight, either on Earth or Mars.

Those CoeLux lights are nice.   I found a spec sheet.  They consume around 300W to to light an area of 20m2, which doesn't seem too bad for 'natural' light? 

The 1700 x 850 mm skylight is 3759 x 2274 x 966 mm unit.  It's not clear how they're assembled.  If they can only be shipped as a unit makes it quite a luxury item. 

http://cdn.shopify.com/s/files/1/1046/0812/files/CoeLux__Datasheets_UL_1.pdf?13310844782056675942
Natural light is anything up to 1000 W/m2, so this is an illusion.  I think te effect is great, but probably wouldn't be all that good for plant growth.  15 W/m2 is standard office lighting levels.
Grow rooms in interior plant production are about 500W/m2 when the lights are on.  Quite blinding and uncomfortable, actually.

For plant growth / vertical farming it's more energy efficient to use purple LEDs. I wasn't suggesting coelux for that.  It should help with the well-being of the humans though.
How high can vertical farm elements be stacked?

Some makes with automated racks can go up several stories. I'd have though that stacking wouldn't be optimal on Mars?  Tunnels would probably be cheaper/ easier to build than shafts or towers?  A Mars variant of the self contained container farms seems like a sensible way to go.  You can distribute farms all over the place.

I've looked a couple of times at indoor farming just out of curiousity.  I found it hard to envisage where actual performance could be for Mars. There's loads of start ups, all promising improvements to energy efficiency, automation and water consumption.

Seems like you would need no more than 50% of the energy us of an Earth greenhouse.  Water consumption would be significantly lower.  They are almost a closed loop, so the risk of crop collapse compared to a greenhouse is small.

I haven't looked a vat grown food production.  In principle you can cover off protein needs without it.  Stuff like Quorn (Mycoprotien) seems like it has its place though.  That's quite an industrial process.  I'm not sure at what point a colony invests in such a thing or whether you can set up mini/local fermentation and processing lines instead.

(Hopefully I've not deviated too far into the agriculture thread's territory)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/14/2018 09:34 am
How high can vertical farm elements be stacked?

Can you elaborate? "Elements"?

a tunnel is not the most efficient volume. To save on construction costs i would like to stack grow trays (elements)  up to 5m high, rather like a automated warehouse.  Is this possible?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 12/14/2018 10:34 am
How high can vertical farm elements be stacked?

Can you elaborate? "Elements"?

a tunnel is not the most efficient volume. To save on construction costs i would like to stack grow trays (elements)  up to 5m high, rather like a automated warehouse.  Is this possible?

Warehouse farming is pretty much what most of these companies are pimping.

Random pics if you want to go down that rabbit hole:

https://www.google.com/search?q=vertical+farming+warehouse&rls=com.microsoft:en-GB:IE-Address&source=lnms&tbm=isch&sa=X&ved=0ahUKEwioiqrTnJ_fAhUJC-wKHb2pCmgQ_AUIDigB&biw=1050&bih=680
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/14/2018 01:02 pm
Since plants can grow at very low air pressures, inflatable transparent greenhouses are feasible. Presumably it would not be too hard to produce ones with locally manufactured glass or even plastics. I'm sure they could also be scaled up to 5m height, with a bit of thickening. Whether or not it's something you want to put in your colony architecture is up to you.

My personal view on a Mars colony is that there would be a lot of different organisations bringing their own things to the table, just like the ISS. So you wouldn't necessarily have one monolithic design for everything. NASA might decide a buried LED-let greenhouse is the way to go, and then a Japanese corporation decides to grow rice* in transparent greenhouses on the surface.

*amazingly radiation resistant
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/14/2018 05:56 pm
How high can vertical farm elements be stacked?

Can you elaborate? "Elements"?

a tunnel is not the most efficient volume. To save on construction costs i would like to stack grow trays (elements)  up to 5m high, rather like a automated warehouse.  Is this possible?

Warehouse farming is pretty much what most of these companies are pimping.

Random pics if you want to go down that rabbit hole:

https://www.google.com/search?q=vertical+farming+warehouse&rls=com.microsoft:en-GB:IE-Address&source=lnms&tbm=isch&sa=X&ved=0ahUKEwioiqrTnJ_fAhUJC-wKHb2pCmgQ_AUIDigB&biw=1050&bih=680
Thanks for the images.  Some of this, some of that, not the entire food supply but probably some percentage of it would be in racks.  There are other intensive methods that might be useful as well.
Then there will be some algae tanks for animal feed and oil, plus some chickens and rabbits, and some sort of rice.  Herb gardens, probably in the habitats themselves, to add variety cheaply.  Tilapia fish.  the usual, I guess.
I'm planing on a lot of variation in lighting intensity, with many very high lighting levels in the corridors with plants, and lower levels elsewhere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/14/2018 05:59 pm
Since plants can grow at very low air pressures, inflatable transparent greenhouses are feasible. Presumably it would not be too hard to produce ones with locally manufactured glass or even plastics. I'm sure they could also be scaled up to 5m height, with a bit of thickening. Whether or not it's something you want to put in your colony architecture is up to you.

My personal view on a Mars colony is that there would be a lot of different organisations bringing their own things to the table, just like the ISS. So you wouldn't necessarily have one monolithic design for everything. NASA might decide a buried LED-let greenhouse is the way to go, and then a Japanese corporation decides to grow rice* in transparent greenhouses on the surface.

*amazingly radiation resistant
I'm rather worried about freezing greenhouses during the night. There will be lots of radiation losses at night.
But I'm planning on a reasonable messy colony, with some abandonned elements and a large variety of arrangements.
Although the compressed earth blocks technology might be involved in many of the arrangements.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/15/2018 03:10 am
Since plants can grow at very low air pressures,

Plants become less productive at lower pressure, and eventually become dormant. They transpire more as the pressure drops until eventually they can't draw enough water to keep up. Essentially they go into a drought state regardless of how much water is available.

This has been discussed several times in the Scaling Ag thread.

[Aside: Can't find a maximum pressure though.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/15/2018 03:42 am
Then there will be some algae tanks for animal feed and oil, plus some chickens and rabbits, and some sort of rice.  Herb gardens, probably in the habitats themselves, to add variety cheaply.  Tilapia fish.  the usual, I guess.

I'd add insects. You can raise larva on human/animal waste. Then feed the larva to the fish and chickens. (Chickens apparently adore eating insect larva; not only is it a protein rich diet, but it seems psychologically positive for the animals compared to normal feed, reducing their stress response.) The three-species process (humans-insects-chickens-humans) should virtually eliminate re-infection of humans from their own waste, assuming there are infectious agents we can't exclude by quarantine. The insect waste itself ("frass") should be directly suitable for plant fertilisation.

(And insects and worms raised on plant waste could be eaten directly by humans, if the settlers are so inclined. And again the frass and castings should be directly suitable for plant fertilisation.)

I'm rather worried about freezing greenhouses during the night. There will be lots of radiation losses at night.

Not just radiation. As I've said, conduction to air dominates at modest wind-speed. (And therefore heat loss will be complex to model.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/15/2018 05:56 am
Since plants can grow at very low air pressures,

Plants become less productive at lower pressure, and eventually become dormant. They transpire more as the pressure drops until eventually they can't draw enough water to keep up. Essentially they go into a drought state regardless of how much water is available.

This has been discussed several times in the Scaling Ag thread.

[Aside: Can't find a maximum pressure though.]
Agreed, wonder how this might affect algea growth in surface bags, since they obviously don't have the same problem.  And plastic bags fllled of water would have high thermal inertia.  A double wall, typical of greenhouses on Earth, with low emissivity films, might allow for a low surface temperature at the outer surface and both low radiation and low convection?  At the same time the film probably reduces heat gain during the dat, so don't know how it work out overall.  Probably need to insulate on the ground side though.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/15/2018 06:04 am
Then there will be some algae tanks for animal feed and oil, plus some chickens and rabbits, and some sort of rice.  Herb gardens, probably in the habitats themselves, to add variety cheaply.  Tilapia fish.  the usual, I guess.

I'd add insects. You can raise larva on human/animal waste. Then feed the larva to the fish and chickens. (Chickens apparently adore eating insect larva; not only is it a protein rich diet, but it seems psychologically positive for the animals compared to normal feed, reducing their stress response.) The three-species process (humans-insects-chickens-humans) should virtually eliminate re-infection of humans from their own waste, assuming there are infectious agents we can't exclude by quarantine. The insect waste itself ("frass") should be directly suitable for plant fertilisation.

(And insects and worms raised on plant waste could be eaten directly by humans, if the settlers are so inclined. And again the frass and castings should be directly suitable for plant fertilisation.)

I'm rather worried about freezing greenhouses during the night. There will be lots of radiation losses at night.

Not just radiation. As I've said, conduction to air dominates at modest wind-speed. (And therefore heat loss will be complex to model.)
Insects sounds good.  Wonder of we should create soils just to add bacterial mass to the overall system, after all that is what the worms eat.  Even if this is not the 'optimum' hydro-aqua' design, can't help thinking soil is a localy produced ressource, and adding to the biomass of the colony through bacteria is probably a good thing.  Bacteria can produce biomass using less energy than plants, I expect?

The idea beeing that the optimum form of a pressure vessel (circular section) is not the idea form for a habitat, because an arc is not a good floor, but if we simply fill the bottom of the habitat with regolith, water and bacteria, we'll eventually get a surface that is walkable.
There are perhaps issues with humidity in the soil though, and too much bacteria might be a problem.  I'm already worried a habitat would be a bit swampy, because of all the thermal energy and evapotrasnpiration from food production.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/15/2018 06:06 am
Then there will be some algae tanks for animal feed and oil, plus some chickens and rabbits, and some sort of rice.  Herb gardens, probably in the habitats themselves, to add variety cheaply.  Tilapia fish.  the usual, I guess.

I'd add insects. You can raise larva on human/animal waste. Then feed the larva to the fish and chickens. (Chickens apparently adore eating insect larva; not only is it a protein rich diet, but it seems psychologically positive for the animals compared to normal feed, reducing their stress response.) The three-species process (humans-insects-chickens-humans) should virtually eliminate re-infection of humans from their own waste, assuming there are infectious agents we can't exclude by quarantine. The insect waste itself ("frass") should be directly suitable for plant fertilisation.

(And insects and worms raised on plant waste could be eaten directly by humans, if the settlers are so inclined. And again the frass and castings should be directly suitable for plant fertilisation.)

I'm rather worried about freezing greenhouses during the night. There will be lots of radiation losses at night.

Not just radiation. As I've said, conduction to air dominates at modest wind-speed. (And therefore heat loss will be complex to model.)
Conduction can be tricky, perhaps not with a single wall greenhouse, but with any double walled or insulated vessel you can get surface temperature that are close to the environment temperatures and that make convection very low. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/15/2018 06:11 am
General view of the colony.

Rather than greenhouses, long compressed Earth block structures with pressure resistant hoops and artificial lighting (600 W/m2 peak, 300 W/m2 average) serve for food production.  They are not buried as plants are more resistant to radiation damage.  Plant nurseries might be in covered areas though.

A solar farm slightly larger than 1km x 1km provides power.  Fuel production and some food production are stopped during storms, leaving plenty of energy to run the habitat.

The colony has already tunneled entirely through the crater rim and the small plateau, and emerged on the other side.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 12/15/2018 04:27 pm
>
I'd add insects. You can raise larva on human/animal waste. Then feed the larva to the fish and chickens. (Chickens apparently adore eating insect larva; not only is it a protein rich diet, but it seems psychologically positive for the animals compared to normal feed, reducing their stress response.)
>

Certain breeds of duck should be in the mix. For meat they mature to harvest quickly, they also eat larvae, and they can produce ~25-30% larger and more nutritious eggs than chickens. Their prodigious levels of manure is also easier to manage and process into fertilizer than chicken droppings. Many advantages.
Title: Re: Envisioning Amazing Martian Habitats
Post by: alexterrell on 12/15/2018 07:24 pm
Those CoeLux lights are nice. [...] They consume around 300W to to light an area of 20m2, which doesn't seem too bad for 'natural' light?
For plant growth / vertical farming it's more energy efficient to use purple LEDs. I wasn't suggesting coelux for that.  It should help with the well-being of the humans though.

Actually, 15W/m2 is too low for humans too. You need exposure to brighter lights for healthy eye development. And there are issues associated with dim light and depression (beyond the vitamin D connection.)

They give a nice ambience. That's all.

(Also 15W/m2 is the power consumption, unless they've discovered 100% efficient lights, I'm assuming the actual watts of light energy is lower. But the figure gives us a ceiling. No pun intended.)

The human eye is quite remarkable at adjusting to different levels, to the point the brain doesn't realise the light range.

Back in the old days, a 20m2 room might have been lit with a 100W incandescent (about 15W of LED), giving about 5 Watts of light over 20m2. These days with LEDs we demand a lot more, and offices have been better lit since flourescent tubes were deployed. 

At the other extreme, sunlight is giving about 1000W/m2. Hence we used to go outside for our light and our vitamin D.

The CoeLux lights (15W LEDs per m2) will be bright for an office, and very bright for a home. But their main purpose is to fool your senses into thinking that there is sunlight outside, and that the skylight is a real window - hence I assume they are 6000K LEDs. Whilst they may not help you make vitamin D, they should make you feel better.

These lights offset the need for real windows. On a Mars colony, they could be placed in common areas to give ambience. Not for domestic areas or for plant growth. And I assume humans might still like a sunbed (perhaps 100W/m2) for 30 minutes per week.

The brochure I've seen suggests the units are quite deep (IIRC 400mm?) and bulky, but it should be easy to make all but the LED itself on Mars at some point. 

(Edit: https://www.engineeringtoolbox.com/light-level-rooms-d_708.html gives lighting needs for different levels. The remarkable thing is the difference between sunlight and indoors)
Title: Re: Envisioning Amazing Martian Habitats
Post by: brainbit on 12/15/2018 10:38 pm
As a starter I would look for a trench maybe 20m wide and 20m deep and perhaps 2km long and maybe running north south. You can dig out the sides to build pressurized habitats. If you cover over the top with ISRU glass and concrete, and pressurize the hole trench with martian air to start .5 psi which would allow water to form and stay on the surface and build to say 4.5 psi as you plug all the holes so that you would not need a spacesuit to go into this environment just a breathing apparatus and tight suit. I believe the EVA space suit use 4.5 psi. The pressure on Everest is similar 5.5 psi.   
You can develop the environment for a pond big enough for water plants, and as your environment matures grow moss which survives CO2 saturation and produces O2. 
You could start by covering just the first 50m at 10m above the bottom and a wall at the end to make the ISRU not to daunting, and as you expand fill in the trench bit by bit with walls between each section to protect against complete decompression. At some point you would be able to build sections strong enough to make the pressure high enough and the air good enough to walk around in normal cloths. The radiation in the bottom of the trench will be considerably less than on the surface and your exposure could be controlled.
It would be a good start.....  ;)       
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/16/2018 06:26 am
Actually, 15W/m2 is too low for humans too. You need exposure to brighter lights for healthy eye development. And there are issues associated with dim light and depression (beyond the vitamin D connection.)
The human eye is quite remarkable at adjusting to different levels, to the point the brain doesn't realise the light range.

Yes, but you need the higher end of the range to develop properly. At least according to current research.

(In the first study that came up on Google, link (https://iovs.arvojournals.org/article.aspx?articleid=2466239) (note: axial eye growth is what causes myopia), the top group averaged 1450 lux. You can get that going outside on an overcast day, or wearing dark sunglasses on a sunny day. Or a white room 8 feet away from a 7000W incandescent bulb. Seven thousand. I've other papers previously, where they eliminated pretty much all other associations except genetic. Childhood myopia has nothing to do with close-work, computers/phones/books, lack of exercise, or vitamin D. It's purely down to light exposure.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 12/16/2018 08:20 am

Electrek have obtained details of Tesla's megapacks.  23′-5″ (7.14m) x 5′-3″ (1.60m) with a capacity of around 2,673 kWh.  Not sure what you need to adapt them for Mars, assuming you have them sat on the surface.  There's a plan of the 1.2MWh California facility in the article.

https://electrek.co/2018/12/15/tesla-megapack-debut-giant-energy-storage/
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 12/16/2018 10:32 pm

Electrek have obtained details of Tesla's megapacks.  23′-5″ (7.14m) x 5′-3″ (1.60m) with a capacity of around 2,673 kWh.  Not sure what you need to adapt them for Mars, assuming you have them sat on the surface.  There's a plan of the 1.2GWhMWh California facility in the article.

https://electrek.co/2018/12/15/tesla-megapack-debut-giant-energy-storage/

Fixed that for you.  ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/29/2018 12:52 pm
For anyone interested: rakaydos has spun off a thread for the solar way-station idea.

Designing a Solar Power Rover Waystation (https://forum.nasaspaceflight.com/index.php?topic=47042.0)
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 12/29/2018 04:47 pm
The independent wheel electrical drive (and steering) could also allow units (vehicles including habs, labs, facilities etc) to move IN ANY DIRECTION. (including vertical adjustment) This could make assembly of a 2D multi unit base easier.
Assuming dust is a significant problem, having a system where two vehicles meeting can quickly and easily adjust height, and alignment and connect together so occupants can move between them and use the shared interior volume easily will be a massive enabler. It will reduce the need for suiting up, and the wear and tear on the suiting process. All modules could by default connect to a modular wheel system. This will allow easy siting, and re-siting for example to a new mine, or into large tunneled spaces.
Using at least two habitat vehicles for missions away from "base" will give safety by redundancy. Being able to join them into one space will be a very frequently desired option. It will facilitate professional and social mixing.
Martians will become snails... as they will naturally bring their houses (and labs) with them!
Title: Re: Envisioning Amazing Martian Habitats
Post by: kevinof on 01/08/2019 03:29 pm
Wasn't sure where to put this but when I saw it I thought , wouldn't it make a great exploration vehicle for mars. Ok needs a little work the suspension and drive train is clever and all electric.

https://www.youtube.com/watch?v=A33Yu-9rgxo
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 01/08/2019 07:14 pm
Wasn't sure where to put this but when I saw it I thought , wouldn't it make a great exploration vehicle for mars. Ok needs a little work the suspension and drive train is clever and all electric.

https://www.youtube.com/watch?v=A33Yu-9rgxo

There are 2 issues with the vehicle concept after a quick viewing that needs answering before considering it for Mars exploration.

One is the gel roll up battery packs in the vehicle chassis. They are hard to pair with a thermal management system. The current batteries of that design in the so called "Tesla Killers" automobiles are heavier and less energy efficient then a battery build from an array of 2170 battery cells with embedded coolant conduits. The rolled up gel pack batteries have energy capacity degradation issues due to heat retention in the battery packs. So this type of batteries might not last very long on Mars.

The other issue is how durable the articulated suspension and the drive train is with Martian surface conditions. And if something breaks how many man hours in labor and the stockpile level of required spare parts as compare to a more conventional vehicle design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/08/2019 07:57 pm
Wasn't sure where to put this but when I saw it I thought , wouldn't it make a great exploration vehicle for mars. Ok needs a little work the suspension and drive train is clever and all electric.


There are 2 issues with the vehicle concept after a quick viewing that needs answering before considering it for Mars exploration.

One is the gel roll up battery packs in the vehicle chassis. They are hard to pair with a thermal management system. The current batteries of that design in the so called "Tesla Killers" automobiles are heavier and less energy efficient then a battery build from an array of 2170 battery cells with embedded coolant conduits. The rolled up gel pack batteries have energy capacity degradation issues due to heat retention in the battery packs. So this type of batteries might not last very long on Mars.

The other issue is how durable the articulated suspension and the drive train is with Martian surface conditions. And if something breaks how many man hours in labor and the stockpile level of required spare parts as compare to a more conventional vehicle design.
Although it's nice to have an agile vehicle, I think it makes a lot more, sense, in most cases, to build better roads.  On Mars this might be simpler than on Earth, since there are no swamps and rivers to cross, no forests to cut and if you avoid areas of sand dunes, the regolith should be fairly simple to push around and flatten.  You could go a long way with a shovel and a fairly simple wheeled or even tracked vehicle.
And a flexible platform can see many uses, as per joined image.


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/08/2019 08:01 pm
Working on the details of my full sized base.
Nodes and connectors, or the Tinker Toy base :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 01/08/2019 11:15 pm
Wasn't sure where to put this but when I saw it I thought , wouldn't it make a great exploration vehicle for mars. Ok needs a little work the suspension and drive train is clever and all electric.

https://www.youtube.com/watch?v=A33Yu-9rgxo
At first sight it looks like too many things to go wrong - and spares etc. However all four legs appear the same, a normal car has parts that are specific to front, back, left and right!  So this "levetate" (elevate) has less fiddly parts to work on under the vehicle. I think the capabilities of the vehicle shown would come into their own a bit later, once a base has begun, and there is an urge or need to explore more inaccessible parts of Mars. On Earth mountains can be climbed, and the climbers can camp. On Mars, the suit is somewhat bulky, and the air needs recharging.... and you have to retreat to some kind of "hab" to rest and eat etc. This vehicle provides that. Brilliant.

Simpler versions of wheels on legs have been used by experimental Marion habs. The ability to steer independently, power independently and raise or lower significantly to cope with terrain, to pick up body modules, and to adjust height to attach to other modules all seem invaluable to me for Mars. Just no need to have as great a height, and the walking ability for initial operations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/09/2019 06:43 am
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image)

Is there a reason you have long connector tunnels to small living spaces? As opposed to directly connected living areas, with just archway/walls (and emergency bulkheads) between? Those tunnels seems like a lot more volume to excavate for no purpose except to make everything harder to reach.



Re: Hyundai concept.

Asian motor companies generally give their engineering teams a once-a-year "super-fun-project-time" to play with. They are never serious. (Nissan Cube excepted.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/09/2019 01:58 pm
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image)

Is there a reason you have long connector tunnels to small living spaces? As opposed to directly connected living areas, with just archway/walls (and emergency bulkheads) between? Those tunnels seems like a lot more volume to excavate for no purpose except to make everything harder to reach.



Re: Hyundai concept.

Asian motor companies generally give their engineering teams a once-a-year "super-fun-project-time" to play with. They are never serious. (Nissan Cube excepted.)

The tunnels are the habitats, 10m wide, 7m high, 200m long.  The nodes as well, but less so.  There is one 30m diameter node per 3 tunnels, and each tunnel has 2500 m2 of floor area, while the nodes only have 675 m2, so 7500 to 675 is a ratio of 10 to 1.  But the nodes provide areas of higher volume, plus an 'open' roof to improve the living experience.  About 20 to 25 % of the tunnels are actually common walkways, so the ratio is a little less.
So this is a compromise between volume and floor areas.  Plus the tunnels are much easier to build than the nodes.
The structures are in tunnels, but the tunnels walls are not used as habitat walls.  The actual habitat walls are tunnel liners, built from rock extracted from the tunnels, compressed and improved with a bit of cement.  And held together with post tensioned wires.  This works great for tunnels, not so much for the nodes, that need more costly and complex parts.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/09/2019 02:34 pm

[snip]

The tunnels are the habitats, 10m wide, 7m high, 200m long.  The nodes as well, but less so.  There is one 30m diameter node per 3 tunnels, and each tunnel has 2500 m2 of floor area, while the nodes only have 675 m2, so 7500 to 675 is a ratio of 10 to 1.  But the nodes provide areas of higher volume, plus an 'open' roof to improve the living experience.  About 20 to 25 % of the tunnels are actually common walkways, so the ratio is a little less.
So this is a compromise between volume and floor areas.  Plus the tunnels are much easier to build than the nodes.
The structures are in tunnels, but the tunnels walls are not used as habitat walls.  The actual habitat walls are tunnel liners, built from rock extracted from the tunnels, compressed and improved with a bit of cement.  And held together with post tensioned wires.  This works great for tunnels, not so much for the nodes, that need more costly and complex parts.

I like this design. Nodes and edges, with activities in the nodes and along the edges...

I imagine rows of buildings lining the mostly residential tunnels. These can be "in character", reflecting the Earth origin of the residents (e.g. Victorian mews homes, Boston Back Bay townhouses, etc.). Some tunnels can also be functional, e.g. a greenhouse, industrial...

The open domed spaces can be multilevel and amphitheatric, hosting most non-private buildings which would receive traffic during daytime, e.g. workplaces, pizza joints...
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 01/09/2019 02:42 pm
Yep, as I suggested way way above. I think lamontane has taken some of the ideas from Carfree Cities (http://www.carfree.com/) and run and run with them 👍
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/09/2019 04:58 pm
Exactly! :)
It’s a great ressource.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Dao Angkan on 01/09/2019 11:07 pm
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image)

Is there a reason you have long connector tunnels to small living spaces? As opposed to directly connected living areas, with just archway/walls (and emergency bulkheads) between? Those tunnels seems like a lot more volume to excavate for no purpose except to make everything harder to reach.



Re: Hyundai concept.

Asian motor companies generally give their engineering teams a once-a-year "super-fun-project-time" to play with. They are never serious. (Nissan Cube excepted.)

The tunnels are the habitats, 10m wide, 7m high, 200m long.  The nodes as well, but less so.  There is one 30m diameter node per 3 tunnels, and each tunnel has 2500 m2 of floor area, while the nodes only have 675 m2, so 7500 to 675 is a ratio of 10 to 1.  But the nodes provide areas of higher volume, plus an 'open' roof to improve the living experience.  About 20 to 25 % of the tunnels are actually common walkways, so the ratio is a little less.
So this is a compromise between volume and floor areas.  Plus the tunnels are much easier to build than the nodes.
The structures are in tunnels, but the tunnels walls are not used as habitat walls.  The actual habitat walls are tunnel liners, built from rock extracted from the tunnels, compressed and improved with a bit of cement.  And held together with post tensioned wires.  This works great for tunnels, not so much for the nodes, that need more costly and complex parts.

I love your designs, but interested in why are the tunnels non-circular (10 x 7)? I'm guessing that you're using roadheaders instead of TBMs, so that these dimensions are optimal?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/09/2019 11:53 pm
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1538215;image)

Is there a reason you have long connector tunnels to small living spaces? As opposed to directly connected living areas, with just archway/walls (and emergency bulkheads) between? Those tunnels seems like a lot more volume to excavate for no purpose except to make everything harder to reach.



Re: Hyundai concept.

Asian motor companies generally give their engineering teams a once-a-year "super-fun-project-time" to play with. They are never serious. (Nissan Cube excepted.)

The tunnels are the habitats, 10m wide, 7m high, 200m long.  The nodes as well, but less so.  There is one 30m diameter node per 3 tunnels, and each tunnel has 2500 m2 of floor area, while the nodes only have 675 m2, so 7500 to 675 is a ratio of 10 to 1.  But the nodes provide areas of higher volume, plus an 'open' roof to improve the living experience.  About 20 to 25 % of the tunnels are actually common walkways, so the ratio is a little less.
So this is a compromise between volume and floor areas.  Plus the tunnels are much easier to build than the nodes.
The structures are in tunnels, but the tunnels walls are not used as habitat walls.  The actual habitat walls are tunnel liners, built from rock extracted from the tunnels, compressed and improved with a bit of cement.  And held together with post tensioned wires.  This works great for tunnels, not so much for the nodes, that need more costly and complex parts.

I love your designs, but interested in why are the tunnels non-circular (10 x 7)? I'm guessing that you're using roadheaders instead of TBMs, so that these dimensions are optimal?
Exactly.  I used the joined Roadheader for specs, but they would have to lower the mass a bit for the Mars Edition and make the width just a bit larger  :-)
I am a bit worried an oval shape would fail as a pressure vessel, even though the blocks are preformed for it, and might require too much butteressing from the tunnel walls.  Some of the section shapes  looked at are joined.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 01:27 am
Tunnel cutaway.

The rooms, to the left, will have normal interior lighting.  The corridor will have stronger lighting, sufficient for non interior plants.
Seems it improves eyesight, overtime, and in particular in children.
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 01/10/2019 08:14 am
Tunnel cutaway.

The rooms, to the left, will have normal interior writing.  The corridor will have stronger lighting, sufficient for non interior plants.
Seems it improves eyesight, overtime, and in particular in children.

And basically the same design from Ceres in "The Expanse":
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 10:26 am
Tunnel cutaway.

The rooms, to the left, will have normal interior writing.  The corridor will have stronger lighting, sufficient for non interior plants.
Seems it improves eyesight, overtime, and in particular in children.

And basically the same design from Ceres in "The Expanse":
Yes, except I don't use spin gravity (and tear my asteroid apart but that's an issue for another thread).  It's a logical arrangement, walls for private, center for public. A street is  basically the same thing, so I'm reinventing the street :-).  In my case I don't have space for two rows of rooms/houses, but I expect a future, larger version of the habitat would.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/10/2019 02:02 pm
As a starter I would look for a trench maybe 20m wide and 20m deep and perhaps 2km long and maybe running north south. You can dig out the sides to build pressurized habitats. If you cover over the top with ISRU glass and concrete, and pressurize the hole trench with martian air to start .5 psi which would allow water to form and stay on the surface and build to say 4.5 psi as you plug all the holes so that you would not need a spacesuit to go into this environment just a breathing apparatus and tight suit. I believe the EVA space suit use 4.5 psi. The pressure on Everest is similar 5.5 psi.   
You can develop the environment for a pond big enough for water plants, and as your environment matures grow moss which survives CO2 saturation and produces O2. 
You could start by covering just the first 50m at 10m above the bottom and a wall at the end to make the ISRU not to daunting, and as you expand fill in the trench bit by bit with walls between each section to protect against complete decompression. At some point you would be able to build sections strong enough to make the pressure high enough and the air good enough to walk around in normal cloths. The radiation in the bottom of the trench will be considerably less than on the surface and your exposure could be controlled.
It would be a good start.....  ;)       

Or just dig a tunnel, plug it and have a shirt-sleeve environment from Day 1.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 02:31 pm
As a starter I would look for a trench maybe 20m wide and 20m deep and perhaps 2km long and maybe running north south. You can dig out the sides to build pressurized habitats. If you cover over the top with ISRU glass and concrete, and pressurize the hole trench with martian air to start .5 psi which would allow water to form and stay on the surface and build to say 4.5 psi as you plug all the holes so that you would not need a spacesuit to go into this environment just a breathing apparatus and tight suit. I believe the EVA space suit use 4.5 psi. The pressure on Everest is similar 5.5 psi.   
You can develop the environment for a pond big enough for water plants, and as your environment matures grow moss which survives CO2 saturation and produces O2. 
You could start by covering just the first 50m at 10m above the bottom and a wall at the end to make the ISRU not to daunting, and as you expand fill in the trench bit by bit with walls between each section to protect against complete decompression. At some point you would be able to build sections strong enough to make the pressure high enough and the air good enough to walk around in normal cloths. The radiation in the bottom of the trench will be considerably less than on the surface and your exposure could be controlled.
It would be a good start.....  ;)       

Or just dig a tunnel, plug it and have a shirt-sleeve environment from Day 1.
The tunnel will start out at -50C, shirtsleeves will have to wait for a bit.  If there is any water frozen in the soil it will melt as the tunnel gets warmer.  This might destabilize parts of the walls, and cause never ending humidity problems in the tunnel itself.  The warm zone around the tunnel will progressively get larger and larger, until equilibrium is reached with the soil and the atmospheric heat loss.  This might have unforeseen results somewhere down the line, as most rock is fractured.
Rock at depth, such as basalt or granite, may be quite hard, and require more energy to dig into.  And will still be cold.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 04:43 pm
Typical floor plan and cutaway view.
Each tunnel should house about 150 people at maximum density and fairly small rooms, 2,85 x 3.3.

Tunnel walls are 400mm thick, floors and interior walls are 150mm.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 01/10/2019 05:23 pm
Typical floor plan and cutaway view.
Each tunnel should house about 150 people at maximum density and fairly small rooms, 2,85 x 3.3.

Tunnel walls are 400mm thick, floors and interior walls are 150mm.
Suggestion have a wall (structural if necessary) running down the centre line. Extend the upper deck right across the width of the tunnel doubling space in that area. Move the car deck towards the centre line and lower the deck slightly on that side.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 06:41 pm
Typical floor plan and cutaway view.
Each tunnel should house about 150 people at maximum density and fairly small rooms, 2,85 x 3.3.

Tunnel walls are 400mm thick, floors and interior walls are 150mm.
Suggestion have a wall (structural if necessary) running down the centre line. Extend the upper deck right across the width of the tunnel doubling space in that area. Move the car deck towards the centre line and lower the deck slightly on that side.
Seems to work well.  Thanks
The only caveat I have, and it it entirely subjective as I have no real expertise on the subject, is that I feel having a 'corridor' with a higher ceiling creates a better indoor outdoor effect, and therefore a better overall quality of life.
I expect the corridors should switch left to right at least once in the corridor to break up excessive regularity, and perhaps have a wider space near the center so two vehicles can pass.
As these are automated vehicles and most of the displacements will be by walking from the traffic hubs the problem shouldn't arise, but just in case.  Also provides an opportunity for a little public space.

If you need a far perspective, you can climb up to the dome :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 01/10/2019 06:49 pm
In my view, the tunnel design is wasting open space by having a dedicated, walled-off passage just for vehicles, especially because I'm not clear just how much traffic a colony will initially have (thus making this space largely unused).  I much prefer "The Expanse" approach, where the vehicle space is also a public area that is accessible to pedestrians, and provides more open air for residents.  There is no reason that pedestrian and vehicle spaces shouldn't mix, as the vehicle speeds will likely be low (and the vehicles automated).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/10/2019 07:12 pm
Or just dig a tunnel, plug it and have a shirt-sleeve environment from Day 1.
The tunnel will start out at -50C, shirtsleeves will have to wait for a bit.  If there is any water frozen in the soil it will melt as the tunnel gets warmer.  This might destabilize parts of the walls, and cause never ending humidity problems in the tunnel itself.  The warm zone around the tunnel will progressively get larger and larger, until equilibrium is reached with the soil and the atmospheric heat loss.  This might have unforeseen results somewhere down the line, as most rock is fractured.
Rock at depth, such as basalt or granite, may be quite hard, and require more energy to dig into.  And will still be cold.

I prefer the idea of boring into stable bedrock. However, if that is not possible it would of course be necessary to line the tunnel with ISRU lining elements. Those would help insulate the tunnel, but sure, it may be a parka coat rather than a shirt-sleeve environment in the beginning... :-)

As for inhabiting circular tunnels I think the upper area, due to its low ceiling, would be good for sleeping quarters.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/10/2019 07:19 pm
In my view, the tunnel design is wasting open space by having a dedicated, walled-off passage just for vehicles, especially because I'm not clear just how much traffic a colony will initially have (thus making this space largely unused).  I much prefer "The Expanse" approach, where the vehicle space is also a public area that is accessible to pedestrians, and provides more open air for residents.  There is no reason that pedestrian and vehicle spaces shouldn't mix, as the vehicle speeds will likely be low (and the vehicles automated).
Agreed. Think shopping mall or airport.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 07:48 pm
In my view, the tunnel design is wasting open space by having a dedicated, walled-off passage just for vehicles, especially because I'm not clear just how much traffic a colony will initially have (thus making this space largely unused).  I much prefer "The Expanse" approach, where the vehicle space is also a public area that is accessible to pedestrians, and provides more open air for residents.  There is no reason that pedestrian and vehicle spaces shouldn't mix, as the vehicle speeds will likely be low (and the vehicles automated).
Ah, I see I have not been clear.
The passage is mainly a walkway and public space.  It's really a large corridor, that happens to be large enough for an automated vehicle.  The vehicle is just there for sizing to ensure there is space enough.  There will be very few vehicles in an area at any given time.  So it is exactly what you describe  :-)
You do want space for a vehicle to deliver packages, or construction materials, or for emergency services.  There will be a bright red vehicle, eventually, with Fire and Leak department written on it.
Actual vehicle circulation at high speed is in separate dedicated 4m tunnels.  These will really come into their own when the colony reaches a few tens of thousands, but will be available from the start. One hub out of six will have a pair of entry and exit points, with higher density in the larger more public tunnels.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 07:54 pm
Or just dig a tunnel, plug it and have a shirt-sleeve environment from Day 1.
The tunnel will start out at -50C, shirtsleeves will have to wait for a bit.  If there is any water frozen in the soil it will melt as the tunnel gets warmer.  This might destabilize parts of the walls, and cause never ending humidity problems in the tunnel itself.  The warm zone around the tunnel will progressively get larger and larger, until equilibrium is reached with the soil and the atmospheric heat loss.  This might have unforeseen results somewhere down the line, as most rock is fractured.
Rock at depth, such as basalt or granite, may be quite hard, and require more energy to dig into.  And will still be cold.

I prefer the idea of boring into stable bedrock. However, if that is not possible it would of course be necessary to line the tunnel with ISRU lining elements. Those would help insulate the tunnel, but sure, it may be a parka coat rather than a shirt-sleeve environment in the beginning... :-)

As for inhabiting circular tunnels I think the upper area, due to its low ceiling, would be good for sleeping quarters.
The interesting gain (theoretical of course, no one really knows) of boring into sandstone closer to the surface would be that the work is not so difficult, and that voids are very likely to be filled with ice, so you dig for your ice and your tunnel at the same time.  15% water ice seems possible, and if you leave 5% of water and mix it with cement made from nearby carbonate deposits, desiccated into cement, you get concrete, or compressed Earth blocks.
Access to natural lighting is also possible, that would be useless in a deeper base.
And if the sandstone is mixed with magnetic type iron ore dust, as is very likely, you get your rock source, your glass source, your water (hydrogen/oxygen)source, your iron source and probably some titanium as well.
All that is left to do is extract CO2 and Nitrogen from the atmosphere and you have all your primary materials.
You do need a separate carbonate mine.  Nearby clays would also be nice, not the best source of aluminium but they can be quite concentrated here on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 01/10/2019 07:56 pm
The passage may be useful as a walkway, but (if I'm reading the drawing correctly) because it is not aligned with and open to the residential areas, it can't serve as a pedestrian mall and public square. 

As for package delivery, have you considered running small autonomous vehicles at the very lowest levels, under the residential levels?  This is space that otherwise isn't usable by people (unlike the large vehicle space).  This approach is somewhat like what Sidewalk Labs is proposing for its waterfront development in Toronto -- move the "utility" functions underground and out of the way, and leave streets largely for pedestrians.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 08:13 pm
The passage may be useful as a walkway, but (if I'm reading the drawing correctly) because it is not aligned with and open to the residential areas, it can't serve as a pedestrian mall and public square. 

As for package delivery, have you considered running small autonomous vehicles at the very lowest levels, under the residential levels?  This is space that otherwise isn't usable by people (unlike the large vehicle space).  This approach is somewhat like what Sidewalk Labs is proposing for its waterfront development in Toronto -- move the "utility" functions underground and out of the way, and leave streets largely for pedestrians.
Here is a wider view showing the transportation tunnels.  Think Boring company, of course.
The passageway is sized for a vehicle, but mostly used as a common walking and living area.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 01/10/2019 08:34 pm
Is the upper part of the vehicle passage intended to be a "balcony" for the upper level residential?

(I'd also suggest that any vehicle passage should accommodate at least two vehicle widths, otherwise a single breakdown could completely prevent traffic flow.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 08:41 pm
Is the upper part of the vehicle passage intended to be a "balcony" for the upper level residential?

(I'd also suggest that any vehicle passage should accommodate at least two vehicle widths, otherwise a single breakdown could completely prevent traffic flow.)
Yes, it's a balcony.
Two vehicle width is unfortunately too large.  I have driven in a number of small European towns that do not provide two vehicle widths ;-). 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 01/10/2019 08:48 pm
I'd strongly suggest a re-think of either the tunnel size, "street" width, or size of vehicle.  The difference between a Mars hab and a European town is that there are far more limited ways to get to one's destination in the former.  You really don't want a vehicle breakdown to be an emergency.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/10/2019 08:54 pm
The interesting gain (theoretical of course, no one really knows) of boring into sandstone closer to the surface would be that the work is not so difficult, and that voids are very likely to be filled with ice, so you dig for your ice and your tunnel at the same time.  15% water ice seems possible, and if you leave 5% of water and mix it with cement made from nearby carbonate deposits, desiccated into cement, you get concrete, or compressed Earth blocks.

Carbonate deposits on Mars?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 10:01 pm
I'd strongly suggest a re-think of either the tunnel size, "street" width, or size of vehicle.  The difference between a Mars hab and a European town is that there are far more limited ways to get to one's destination in the former.  You really don't want a vehicle breakdown to be an emergency.
I'll go for vehicle size.  Consider the vehicles shrunk about 80%.  We hardly need 12 erson buses in an early colony anyway.
However, in an hexagonal nodal construction, the basic layout of this colony, there are always at least three ways to a node, up tp 6 for a central node, and 2 ways to any spot.  So the problem is unlikely, but small vehicles solve it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/10/2019 10:03 pm
The interesting gain (theoretical of course, no one really knows) of boring into sandstone closer to the surface would be that the work is not so difficult, and that voids are very likely to be filled with ice, so you dig for your ice and your tunnel at the same time.  15% water ice seems possible, and if you leave 5% of water and mix it with cement made from nearby carbonate deposits, desiccated into cement, you get concrete, or compressed Earth blocks.

Carbonate deposits on Mars?
https://en.wikipedia.org/wiki/Carbonates_on_Mars

Seems believable?
Title: Re: Envisioning Amazing Martian Habitats
Post by: WindyCity on 01/10/2019 10:31 pm

Basically impossible to discuss without knowing the effect of partial gravity on human health.t
A possible solution to surviving in a low-G environment would be regular centrifuge treatments.Options such as this were discussed at length in an inactive forum called "Artificial Gravity -punctuated gravity using a centrifuge". (Also, check out https://forum.nasaspaceflight.com/index.php?topic=42844.0) bviously, it's scandalous that artificial grav hasn't been tested in LEO using animal subjects.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/11/2019 02:35 am
The colony, with two traffic tunnels bellow.
No one is ever more than 200m away from a station where a vehicle can be boarded.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 01/11/2019 02:46 am
How about instead of maintaining a single continuous run of residence on one side, vehicle passage on the other, alternate the sides so that it is less obviously a long tunnel going to "infinity".

This would waste some volume probably to leave space for vehicles to cross from one side to the other, but would be more visually interesting. Could also provide an area for two vehicles to pass each other. Maybe 2-4 transitions per tunnel between nodes? If the balcony is a walkway and not a private balcony, add small pedestrian bridges from one side to the other at this crossover areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 01/11/2019 07:38 am
In my view, the tunnel design is wasting open space by having a dedicated, walled-off passage just for vehicles, especially because I'm not clear just how much traffic a colony will initially have (thus making this space largely unused).  I much prefer "The Expanse" approach, where the vehicle space is also a public area that is accessible to pedestrians, and provides more open air for residents.  There is no reason that pedestrian and vehicle spaces shouldn't mix, as the vehicle speeds will likely be low (and the vehicles automated).
Agreed. Think shopping mall or airport.

Images 1 & 2: My local mall has some good domes and skylights for lighting. They're bright, but as you can see in the photos they don't let in that much light. The high dynamic range fools us into thinking there is more light than is actually there - however, it does appear very bright, especially supplemented with artificial lighting.  Note the hanging "clouds" to add a sense of depth.

Image 3: Terrible example of an indoor sky attempt. It actually makes the mall (a pretentious faux-Italian town) feel extremely oppressive as opposed to simply adding bright lights and an actual ceiling.

Image 4: University building. Lots of open "wasted" volume but although it looks like a rather dystopian structure (Johannesburg has plenty of these which is why Dredd was filmed there) it still feels open and airy. The reason for this is overlaid scenery - walkways - and some extra height afforded by the warehouse-type natural lighting. So if you have a groove in the top of the tunnel to add a couple of metres of "wasted" volume you would get a drastic increase in the feeling of openness.

I don't see any reason why a mall-type colony wouldn't have a lot of solar collectors piping daylight-equivalent light down to the mall avenues. You could even set it up so that the roof collects it in conjunction with domes, dial in some natural lighting variation throughout the day to simulate cloudiness.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 01/11/2019 12:49 pm
I think you want to get as much indirect light in as possible, perhaps including the use of mirrors or white surfaces whist avoiding as much direct sunlight as possible in most areas so as to minimise radiation exposure whilst maintaining a pleasant bright environment. I'm sure residents would still get plenty of radiation exposure when they went outside so keeping indoor exposure to the very minimum would be useful.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 01/11/2019 12:58 pm
You would want to colour correct the light too by adding blue light (really important with sleep cycles) to the incident light.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/11/2019 04:38 pm
Lighting will be an interesting problem.  And eventually will create a significant cooling load if the high lighting areas if we want to avoid a depressive and dim colony.
Glass and mirrors have significant losses, as well as significant costs.  It they are large enough for significant amounts of light they are also large enough for radiation to pass through.

There will be an interesting difference in cooling loads between the day and night periods. 

On another tack, for transportation, as the gravity is lower, will the acceleration that can be supported by people in a transit system be lower?  Intuitively, I would guess that someone standing would have more difficulty maintaining stability, so perhaps public transit accelerations will be lower.  Or they will necessarily be done sitting down and even tied in with a seat buckle?
At this point the colony sizing gives acceleration ramps of about 100m long, that translates as 50 km per hour traffic speed with 1m/s2 acceleration.  This appears to be in line with present traffic design, but does it hold on Mars? 
I guess eventually a second tier of tunnels with longer access ramps would give access to an inter district traffic running at higher velocities.  A few decades down the road!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/11/2019 04:54 pm
In my view, the tunnel design is wasting open space by having a dedicated, walled-off passage just for vehicles, especially because I'm not clear just how much traffic a colony will initially have (thus making this space largely unused).  I much prefer "The Expanse" approach, where the vehicle space is also a public area that is accessible to pedestrians, and provides more open air for residents.  There is no reason that pedestrian and vehicle spaces shouldn't mix, as the vehicle speeds will likely be low (and the vehicles automated).
Agreed. Think shopping mall or airport.

Images 1 & 2: My local mall has some good domes and skylights for lighting. They're bright, but as you can see in the photos they don't let in that much light. The high dynamic range fools us into thinking there is more light than is actually there - however, it does appear very bright, especially supplemented with artificial lighting.  Note the hanging "clouds" to add a sense of depth.

Image 3: Terrible example of an indoor sky attempt. It actually makes the mall (a pretentious faux-Italian town) feel extremely oppressive as opposed to simply adding bright lights and an actual ceiling.

Image 4: University building. Lots of open "wasted" volume but although it looks like a rather dystopian structure (Johannesburg has plenty of these which is why Dredd was filmed there) it still feels open and airy. The reason for this is overlaid scenery - walkways - and some extra height afforded by the warehouse-type natural lighting. So if you have a groove in the top of the tunnel to add a couple of metres of "wasted" volume you would get a drastic increase in the feeling of openness.

I don't see any reason why a mall-type colony wouldn't have a lot of solar collectors piping daylight-equivalent light down to the mall avenues. You could even set it up so that the roof collects it in conjunction with domes, dial in some natural lighting variation throughout the day to simulate cloudiness.
The problem with skylights will be radiation protection and line of sight.  The no 4 roof would not be able to provide both side windows and 5m of rock in a practical package, I expect.  However, how much time is spent in a university lobby?
I think some skylight in public spaces and the joined radiation will be acceptable because colonists will pass most of their time in private spaces, sleeping and such, or in commercial/service work spaces with relatively low light levels (as we already collectively do) and high radiation protection.
If you need light therapy, perhaps a week in the greenhouses potting plants would be good and sufficient.  Probably be good anyway, for a multiple of reasons.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Andre Infante on 01/11/2019 10:10 pm
A couple of things, regarding lighting.

The coelux skylights, if you ditch the light scattering stuff, are basically just a big optical collimator. Reading between the lines, it's probably a larger version of the edge-lit waveguides used for AR headsets. The upshot is that you shouldn't take their actual brightness as an upper limit. There are a few different ways of collimating light, and some of them have no practical upper limit on brightness. So daylight-bright fake skylights ought to be plenty tractable, you just need to either budget mass for the collimator, or find a way to make it out of fused quartz.

As far as above-ground lighting goes, I've been thinking about the logistics of dome farming. A conventional dome winds up wasting a lot of volume, because a proper cylindrical or spherical pressure vessel needs to be as tall as it is wide, and plants only grow so high, and if you stack them in the dome, the ones in the middle get heavily shaded. If you make the domes smaller, the space you have to allocate for people maneuvering through them becomes a major waste. You also have to make the glass thicker as the radius of curvature increases.

So how about towers? Specifically, really small ones. 

What I'm thinking is you make capsule-shaped glass pressure vessels, and orient them on end, protruding from a buried fibercrete tunnel. Each capsule is < 1 meter wide, just a bit wider than one of the pots that goes into it, but long - like an oversized, upside-down test tube.

The pots are hydroponic, and designed to interlock vertically like legos, with the plants growing out of openings on the sides. So you seed the pots, stack them up into the greenhouse tower, and circulate water through them. When the crop is mature, you dismantle the stack, harvest, and repeat, leaving the glass tower in place. Humans don't have to go in and out of the glass grow area, so virtually all of the greenhouse space ends up filled (and fully utilized by) plant matter. And, because the radius is small, the pressure vessels can be relatively thin, since the mechanics are more like a car tire than like a space station.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/12/2019 05:16 pm

(...)

Yes, except I don't use spin gravity (and tear my asteroid apart but that's an issue for another thread).  It's a logical arrangement, walls for private, center for public. A street is  basically the same thing, so I'm reinventing the street :-).  In my case I don't have space for two rows of rooms/houses, but I expect a future, larger version of the habitat would.

There are more places to put residences in your design. You can create vertical skylights or wells of roughly the same diameter as the main tunnel and build in levels above or below the main tunnel. If you can afford to cover it with a small dome (note: small domes are easier to handle) then you can drill all the way to the surface and provide small above-ground private spaces for various functions - a roof deck, a private vegetable patch, a private airlock, a private rover garage...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/13/2019 04:12 pm
Surface use of the connector and node system of construction.
The illustration shows the main agricultural section of the colony, built using the same connector and node system with compressed Earth Blocks than proposed for the underground colony.
The connectors are covered with multilayer insulation, micron thin plastic sheets (4 or 5) with ultra thin aluminium foil surfaces.
Solar cells provide the power for the lighting in the connectors, that serve as greenhouses.
The assumption is that the 25-30% efficiency conversion of the artificial lighting system is offset by overall cheaper construction costs, better heat transfer control, in particular lower night losses, and use of more appropriate wavelengths for plant growth. In a sense the photoelectric cells act as a solar concentrator, collecting the power over a large surface and concentrating it into the connectors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: nacnud on 01/13/2019 06:33 pm
With construction on Mars being very resource intensive might it be worth looking at the cheapest forms of housing used on Earth for ideas. Terrace or tenement housing would reduce the need for external walls. Folding a street back on itself to produce irregular blocks would reduce the feeling of living in impersonal surroundings and irregular landmarks aid in navigation. 

I have lived in the UKs only city build on a grid and I was always lost, a semi random close nit selection of streets somehow seems easier to navigate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/13/2019 08:39 pm
With construction on Mars being very resource intensive might it be worth looking at the cheapest forms of housing used on Earth for ideas. Terrace or tenement housing would reduce the need for external walls. Folding a street back on itself to produce irregular blocks would reduce the feeling of living in impersonal surroundings and irregular landmarks aid in navigation. 

I have lived in the UKs only city build on a grid and I was always lost, a semi random close nit selection of streets somehow seems easier to navigate.
Terraced housing can produce both the best and the worst, Edinburgh offering examples of both.  Tenement housing tends towards the worst.  I would expect we would get better results if the colonists owned their houses as in the fancy terrasses of Edinburgh New Town.
The model I am looking at is Estepona in Spain, an upgraded town center that went from run down quasi slum to really good looking area, mostly car free.
Each street has a specific color of flower pot, a simple but effective identification system.  Of course an important part of the visual interest is the high level of lighting.  Narrow streets and not too many floors.
There is a more commercial strip along the beach; this could be provided by a set of larger tunnels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/14/2019 12:50 am
With construction on Mars being very resource intensive might it be worth looking at the cheapest forms of housing used on Earth for ideas. Terrace or tenement housing would reduce the need for external walls. Folding a street back on itself to produce irregular blocks would reduce the feeling of living in impersonal surroundings and irregular landmarks aid in navigation. 

I have lived in the UKs only city build on a grid and I was always lost, a semi random close nit selection of streets somehow seems easier to navigate.

The most resource intensive activity on Mars is propellant production, followed closely by food production.  I think the colony should therefore focus on higher quality construction.  Buried the nodes alittle more in this image and added a pair of rovers
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 01/15/2019 09:30 pm
With construction on Mars being very resource intensive might it be worth looking at the cheapest forms of housing used on Earth for ideas. Terrace or tenement housing would reduce the need for external walls. Folding a street back on itself to produce irregular blocks would reduce the feeling of living in impersonal surroundings and irregular landmarks aid in navigation. 

I have lived in the UKs only city build on a grid and I was always lost, a semi random close nit selection of streets somehow seems easier to navigate.

The most resource intensive activity on Mars is propellant production, followed closely by food production.  I think the colony should therefore focus on higher quality construction.  Buried the nodes alittle more in this image and added a pair of rovers

I see a problem with this architecture of above-ground connecting tunnels - that the surface gets carved up into many hard-to-access small pieces. For this reason one might prefer to place many (most?) tunnels completely underground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 01/16/2019 06:08 am
With construction on Mars being very resource intensive might it be worth looking at the cheapest forms of housing used on Earth for ideas. Terrace or tenement housing would reduce the need for external walls. Folding a street back on itself to produce irregular blocks would reduce the feeling of living in impersonal surroundings and irregular landmarks aid in navigation. 

I have lived in the UKs only city build on a grid and I was always lost, a semi random close nit selection of streets somehow seems easier to navigate.

The most resource intensive activity on Mars is propellant production, followed closely by food production.  I think the colony should therefore focus on higher quality construction.  Buried the nodes alittle more in this image and added a pair of rovers

I see a problem with this architecture of above-ground connecting tunnels - that the surface gets carved up into many hard-to-access small pieces. For this reason one might prefer to place many (most?) tunnels completely underground.

On Earth we solve problems of things being in the way by building ramps over them. :)

As it is, lamontagne's domes have sand berms around them already which function as ramps. Presumably the tunnels would also have airlocks at regular intervals for emergencies anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/16/2019 10:05 pm
With construction on Mars being very resource intensive might it be worth looking at the cheapest forms of housing used on Earth for ideas. Terrace or tenement housing would reduce the need for external walls. Folding a street back on itself to produce irregular blocks would reduce the feeling of living in impersonal surroundings and irregular landmarks aid in navigation. 

I have lived in the UKs only city build on a grid and I was always lost, a semi random close nit selection of streets somehow seems easier to navigate.

The most resource intensive activity on Mars is propellant production, followed closely by food production.  I think the colony should therefore focus on higher quality construction.  Buried the nodes alittle more in this image and added a pair of rovers

I see a problem with this architecture of above-ground connecting tunnels - that the surface gets carved up into many hard-to-access small pieces. For this reason one might prefer to place many (most?) tunnels completely underground.

On Earth we solve problems of things being in the way by building ramps over them. :)

As it is, lamontagne's domes have sand berms around them already which function as ramps. Presumably the tunnels would also have airlocks at regular intervals for emergencies anyway.
Ramp tracks and airlocks added :-).
Road and train tunnels have exits every 750m (or so) according to NFPA requirements in the US.  I believe it is similar in Europe.  I'm not certain a quick exit from a tunnel on Mars is such a good idea though.  I have planned for the colony to be entirely protected by sprinklers and to include fire damper doors at each tunnel entrance.  Actual pressure doors at each tunnel would be a lot more expensive, but perhaps are required.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2019 01:05 am
The agricultural area of the colony.
14 MW of power, 7 km of greenhouses totaling 100 000 m2 of floor area.  For 1000+ inhabitants
There is another 26 MW of power to lay out to complete the power supply.
The fuel production and industrial area is still missing as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/17/2019 01:19 am
The agricultural area of the colony.
14 MW of power, 7 km of greenhouses totaling 100 000 m2 of floor area.  For 1000+ inhabitants
There is another 26 MW of power to lay out to complete the power supply.
The fuel production and industrial area is still missing as well.
Why not a square/rectangular grid? Much better packing with the rectangular solar arrays.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2019 01:32 am
The agricultural area of the colony.
14 MW of power, 7 km of greenhouses totaling 100 000 m2 of floor area.  For 1000+ inhabitants
There is another 26 MW of power to lay out to complete the power supply.
The fuel production and industrial area is still missing as well.
Why not a square/rectangular grid? Much better packing with the rectangular solar arrays.
Land is cheap.  Nodes are expensive.  More connectors for less nodes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 01/17/2019 01:36 am
How about putting an underpass midway along each tunnel ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2019 01:53 am
How about putting an underpass midway along each tunnel ?
Too little surface traffic
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/17/2019 02:28 am
The agricultural area of the colony.
14 MW of power, 7 km of greenhouses totaling 100 000 m2 of floor area.  For 1000+ inhabitants
There is another 26 MW of power to lay out to complete the power supply.
The fuel production and industrial area is still missing as well.
Why not a square/rectangular grid? Much better packing with the rectangular solar arrays.
Land is cheap.  Nodes are expensive.  More connectors for less nodes.
Fewer nodes per area with a square grid, too (with same length between nodes).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2019 11:51 am
The agricultural area of the colony.
14 MW of power, 7 km of greenhouses totaling 100 000 m2 of floor area.  For 1000+ inhabitants
There is another 26 MW of power to lay out to complete the power supply.
The fuel production and industrial area is still missing as well.
Why not a square/rectangular grid? Much better packing with the rectangular solar arrays.
Land is cheap.  Nodes are expensive.  More connectors for less nodes.
Fewer nodes per area with a square grid, too (with same length between nodes).
Not really, perhaps I misunderstand you on this.  I did two attempts, one obviously worse one similar but with two more nodes.  If you add diagonals, then you pretty much get back to the hexagonal case.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2019 11:59 am
On Mars, land is a bit like the sea, essential but without much value until it is converted into habitats.
It's the number of nodes per m2 of living area that is important, not per m2 of land. At least that's how I figure it at this time.
The tunnels are at the recommended maximum length of walking transit recommended in carfree cities.  The central nodes are transit stations for a Boring company type tunnel system.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DougSpace on 01/17/2019 12:28 pm
Initially, large inflatable, flat-roofed habitats make the most sense.  They can be folded and hence packed flat.  They can be constructed on Earth with strong material such as Kevlar and test-proven before shipping/use.  Set up is as easy as opening a valve of condensed air.  With internal tethers holding the roof flat, telerobots can push regolith on top and it won't slough off -- no need to rigidize the shielding.  These processes can be done autonomously-telerobotically prior to crew arrival.

Compared to alternate strategies, this approach has a lot to offer.  The BFR crew compartment won't be sufficiently shielded against GCRs.  3D printing may require binders be sent or sintering requires a lot of power.  Ice limits your base location.  Same thing holds true with lava tubes.  Unlike ice houses, one doesn't have to manage shielding melt.

3D-printed structures won't be as strong as Kevlar-type materials and internal air pressure at 5 tonnes/m2 could well endanger the structural integrity of the habitat.  Flat-packed structures may require crew for assembly.  That crew may not be shielded from GCRs during assembly and shielding construction.

Boring underground means a larger distance to transport extracted material than the additive approach of just telerobotically pushing regolith on top of the inflatable habitat.  If excavating room-shapes areas underground then there is the chance of collapse and supporting the roof while inserting and inflating an air-proof liner could be challenging.

3D printing and boring prior to crew arrival means that machinery breakdown would need to be repaired telerobitically -- not easy.  By comparison, inflating a habitat likely won't involve equipment breakdown although telerobots pushing regolith on top may need worn parts swapped with spares.

In conclusion, I think that large, flat-roofed, inflatable habitats should be given serious consideration.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 01/17/2019 12:38 pm

In conclusion, I think that large, flat-roofed, inflatable habitats should be given serious consideration.

I like the simple automatic first setup.
I also like the roll out solar panels from the spaceship for first power.
Basically rollout 6-8 individual long panels. Should be totally automatic.
What else is easy to do before humans are there or before they even have to leave their ship.

Drillers with hoses for hot water Rodriguez wells?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2019 12:46 pm
Initially, large inflatable, flat-roofed habitats make the most sense.  They can be folded and hence packed flat.  They can be constructed on Earth with strong material such as Kevlar and test-proven before shipping/use.  Set up is as easy as opening a valve of condensed air.  With internal tethers holding the roof flat, telerobots can push regolith on top and it won't slough off -- no need to rigidize the shielding.  These processes can be done autonomously-telerobotically prior to crew arrival.

Compared to alternate strategies, this approach has a lot to offer.  The BFR crew compartment won't be sufficiently shielded against GCRs.  3D printing may require binders be sent or sintering requires a lot of power.  Ice limits your base location.  Same thing holds true with lava tubes.  Unlike ice houses, one doesn't have to manage shielding melt.

3D-printed structures won't be as strong as Kevlar-type materials and internal air pressure at 5 tonnes/m2 could well endanger the structural integrity of the habitat.  Flat-packed structures may require crew for assembly.  That crew may not be shielded from GCRs during assembly and shielding construction.

Boring underground means a larger distance to transport extracted material than the additive approach of just telerobotically pushing regolith on top of the inflatable habitat.  If excavating room-shapes areas underground then there is the chance of collapse and supporting the roof while inserting and inflating an air-proof liner could be challenging.

3D printing and boring prior to crew arrival means that machinery breakdown would need to be repaired telerobitically -- not easy.  By comparison, inflating a habitat likely won't involve equipment breakdown although telerobots pushing regolith on top may need worn parts swapped with spares.

In conclusion, I think that large, flat-roofed, inflatable habitats should be given serious consideration.
It's probably a fine way to start.  However, in the long term in situ production will favor some type of locally produced elements, and concrete, or compressed Earth blocks, and steel are by far the cheapest for this.
Depending on the depth of burial you decide is safe, the shape of the roof is something of a moot point.  I would suggest that simplest is best, in this case.  So whatever is simpler to deploy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/17/2019 12:59 pm

In conclusion, I think that large, flat-roofed, inflatable habitats should be given serious consideration.

I like the simple automatic first setup.
I also like the roll out solar panels from the spaceship for first power.
Basically rollout 6-8 individual long panels. Should be totally automatic.
What else is easy to do before humans are there or before they even have to leave their ship.

Drillers with hoses for hot water Rodriguez wells?
Whatever is used first is unlikely to be still used in the longer run.  And the amazing part probably comes a little latter as well.  As airtight compressed Earth blocks will need at least some cement, be it magnesium or calcium based carbonates, mining, processing and transportation is likely to be required.  I think it is unlikely that they be used from the start, and phase 1 of the Martian habitat will probably be some kind of Earth built module.  But the colonists would probably want to transition towards more permanent quarters, for which they control the means of production, as soon as possible.  And as soon as they start digging, be it trenches or tunnels, there will be all that material at hand that really makes sense to use.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/18/2019 01:23 am
Martian colony Industrial area.
Water tanks in blue, methane tank in yellow.  Eventually they will have berms and insulation.  The Starship is one of the first vehicles that stayed behind.  But perhaps these would be put to work anyway?  There would be a huge solar field nearby.

I wonder what the air compressors for atmospheric extraction might look like?  And what heat rejection systems would look like on Mars?   Water towers are out, so some form of large plates with fans to increase convection?  Perhaps simply something very similar to our dry coolers...

Don't know if I will keep the geodesic domes. Seems expensive and perhaps not required.  Could simply have a thick rock filled plate and wall assembly.  A big tub on top, in a sense.

Of course it's not because it's an industrial area that it has to be ugly.  What could be done to give some aesthetics to this installation?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 01/18/2019 10:08 am
Martian colony Industrial area.
Water tanks in blue, methane tank in yellow.  Eventually they will have berms and insulation.  The Starship is one of the first vehicles that stayed behind.  But perhaps these would be put to work anyway?  There would be a huge solar field nearby.

I wonder what the air compressors for atmospheric extraction might look like?  And what heat rejection systems would look like on Mars?   Water towers are out, so some form of large plates with fans to increase convection?  Perhaps simply something very similar to our dry coolers...

Don't know if I will keep the geodesic domes. Seems expensive and perhaps not required.  Could simply have a thick rock filled plate and wall assembly.  A big tub on top, in a sense.

Of course it's not because it's an industrial area that it has to be ugly.  What could be done to give some aesthetics to this installation?

Why not make use of translucent concrete? 5% of fibre optic strands mixed in with any old concrete, transmits ~2% of light in.

(http://img.archiexpo.com/images_ae/projects/images-og/amazing-translucent-concrete-opens-new-world-design-ideas-55272-12823240.jpg)

You could also model your domes like the fancy Cloud Forest or Flower Domes of Singapore:

(https://www.dinktravelers.com/wp-content/uploads/2017/12/350_Flower-Dome-in-Singapore_Foto_1-768x432.jpg)

http://www.singapore-guide.com/attractions/cloud-forest.htm

Notice how the Cloud Forest dome makes the most use of its vertical space, has rampways etc to take advantage of all that volume. You could Gherkin-ise your domes to stick a tall building inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/18/2019 12:44 pm
Martian colony Industrial area.
Water tanks in blue, methane tank in yellow.  Eventually they will have berms and insulation.  The Starship is one of the first vehicles that stayed behind.  But perhaps these would be put to work anyway?  There would be a huge solar field nearby.

I wonder what the air compressors for atmospheric extraction might look like?  And what heat rejection systems would look like on Mars?   Water towers are out, so some form of large plates with fans to increase convection?  Perhaps simply something very similar to our dry coolers...

Don't know if I will keep the geodesic domes. Seems expensive and perhaps not required.  Could simply have a thick rock filled plate and wall assembly.  A big tub on top, in a sense.

Of course it's not because it's an industrial area that it has to be ugly.  What could be done to give some aesthetics to this installation?

Why not make use of translucent concrete? 5% of fibre optic strands mixed in with any old concrete, transmits ~2% of light in.

You could also model your domes like the fancy Cloud Forest or Flower Domes of Singapore:


Notice how the Cloud Forest dome makes the most use of its vertical space, has rampways etc to take advantage of all that volume. You could Gherkin-ise your domes to stick a tall building inside.
Very interesting. I guess they polish the concrete to 'activate' the embedded fibers? 
Very cool architecture.  I was planning on adding a 'Marvel' to the finished colony along the lines of this dome, that I presented about 50 pages ago ;-) and this arrangement of white elements makes it very striking, visually.
Consider the dome included!
Will think about translucent domes or plates vs glass and steel.  Can fibers be done on the cheap?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 01/18/2019 01:24 pm
Plain old glass fibres are pretty easy to make, maybe easier on a small scale than pressurised plate glass. There are also designs for passive light collectors using flat fresnel lens that also gather up light to convey with a light pipe.

https://www.mdpi.com/2075-5309/7/4/92

You could make the dome out of steel, just having small holes in each section for the gathered light then just spread it out again on the inside. Translucent opaque dome. But having a glass dome, or at least cupolas to see "outside" is still important. The ISS astronauts love their cupola.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DougSpace on 01/18/2019 02:40 pm
lamontagne > However, in the long term in situ production

Yes, I'm not suggesting that large, inflatable, flat-roofed habitats will be the permanent solution but rather would be the solution until ISRU habitats are less expensive mostly in terms of crew time to produce and construct.  That could take a fair amount of time until that point is crossed.

Also, bear in mind that the initial BFRs will be cargo rich and crew poor because you want to risk fewer crew while the transport systems are new and you need to get lots of hardware on the surface before large populations.  So, shipping large inflatables is an easy way of shifting crew time away from constructing (less robust) habitats and towards crew setting up a large number of systems for all sorts of things.  Crew time will be so critical that you don't want for them to have to build habitats upon which their lives depend.  Rather, they should immediately start working inside a safe habitat producing, assembling, and operating hardware to produce as much of the hardware as possible.  Yes, eventually they will produce additional habitats but it shouldn't be the first things that they work on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/18/2019 05:02 pm
lamontagne > However, in the long term in situ production

Yes, I'm not suggesting that large, inflatable, flat-roofed habitats will be the permanent solution but rather would be the solution until ISRU habitats are less expensive mostly in terms of crew time to produce and construct.  That could take a fair amount of time until that point is crossed.

Also, bear in mind that the initial BFRs will be cargo rich and crew poor because you want to risk fewer crew while the transport systems are new and you need to get lots of hardware on the surface before large populations.  So, shipping large inflatables is an easy way of shifting crew time away from constructing (less robust) habitats and towards crew setting up a large number of systems for all sorts of things.  Crew time will be so critical that you don't want for them to have to build habitats upon which their lives depend.  Rather, they should immediately start working inside a safe habitat producing, assembling, and operating hardware to produce as much of the hardware as possible.  Yes, eventually they will produce additional habitats but it shouldn't be the first things that they work on.
I pretty much agree.  Spacex did say that the ships themselves would serve as the earliest habitats.  then I imagine inflatables, then In-Situ.  My own idea is that a practical source of in-situ resources is sandstone deposits with a 10-15% water ice content.  This seems very likely to be common on Mars.  Extracting the water from this source, to create fuel, naturally creates a building resource, slightly humid stone and sand.  when mixed with some treated carbonates it should be a natural building material.  so I expect that as soon as large scale propellant production starts, and that will be pretty fast with the construction rates that Spacex should be able to churn out, CEBs or actual concrete will start being used.
If SpaceX makes only 3 ships per year, after a decade that a fleet of 30 ships..., after 15 years it's 45 ships!  And the oldest one will have only flown 7 times, so it should still be good for a few more.  Even with a low ratio of 4 cargo to 1 passenger ships, it's a lot of people and a lot of fuel production.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/18/2019 05:04 pm
Plain old glass fibres are pretty easy to make, maybe easier on a small scale than pressurised plate glass. There are also designs for passive light collectors using flat fresnel lens that also gather up light to convey with a light pipe.

https://www.mdpi.com/2075-5309/7/4/92

You could make the dome out of steel, just having small holes in each section for the gathered light then just spread it out again on the inside. Translucent opaque dome. But having a glass dome, or at least cupolas to see "outside" is still important. The ISS astronauts love their cupola.
yes, a mix of solutions is the most likely.  I'll sprinkle a few variations around for the various nodes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/18/2019 09:09 pm
Plain old glass fibres are pretty easy to make, maybe easier on a small scale than pressurised plate glass. There are also designs for passive light collectors using flat fresnel lens that also gather up light to convey with a light pipe.

https://www.mdpi.com/2075-5309/7/4/92

You could make the dome out of steel, just having small holes in each section for the gathered light then just spread it out again on the inside. Translucent opaque dome. But having a glass dome, or at least cupolas to see "outside" is still important. The ISS astronauts love their cupola.
yes, a mix of solutions is the most likely.  I'll sprinkle a few variations around for the various nodes.
There you go.  Domes and saltshakers :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 01/21/2019 12:29 pm
Plain old glass fibres are pretty easy to make, maybe easier on a small scale than pressurised plate glass. There are also designs for passive light collectors using flat fresnel lens that also gather up light to convey with a light pipe.

https://www.mdpi.com/2075-5309/7/4/92

You could make the dome out of steel, just having small holes in each section for the gathered light then just spread it out again on the inside. Translucent opaque dome. But having a glass dome, or at least cupolas to see "outside" is still important. The ISS astronauts love their cupola.
yes, a mix of solutions is the most likely.  I'll sprinkle a few variations around for the various nodes.
There you go.  Domes and saltshakers :)

If you want to go full Space Elf, lighting prisms are indeed a thing. They were used as lighting for all sorts of underground and belowdecks situations (pointy side down). The purple colour is from UV ageing not any latent elvish magical properties :P

(https://glassian.org/Prism/Gallery/Deck/triple_spike3.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/21/2019 02:04 pm
Plain old glass fibres are pretty easy to make, maybe easier on a small scale than pressurised plate glass. There are also designs for passive light collectors using flat fresnel lens that also gather up light to convey with a light pipe.

https://www.mdpi.com/2075-5309/7/4/92

You could make the dome out of steel, just having small holes in each section for the gathered light then just spread it out again on the inside. Translucent opaque dome. But having a glass dome, or at least cupolas to see "outside" is still important. The ISS astronauts love their cupola.
yes, a mix of solutions is the most likely.  I'll sprinkle a few variations around for the various nodes.
There you go.  Domes and saltshakers :)

If you want to go full Space Elf, lighting prisms are indeed a thing. They were used as lighting for all sorts of underground and belowdecks situations (pointy side down). The purple colour is from UV ageing not any latent elvish magical properties :P

It seems inevitable that a Steampunk Victorian sector will some day be built on Mars.  These seem likely to find use there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/22/2019 01:43 am
Lampyridae's Dome!

Why build a boring dome when you can build a dome with style!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/26/2019 07:43 pm
A help for builders on Mars perhaps...

AR bricklaying:

https://www.archdaily.com/908618/this-is-how-a-complex-brick-wall-is-built-using-augmented-reality?ad_medium=widget&ad_name=most-visited-index
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/27/2019 05:03 am
A view of the production area on Mars.

Large methane tank in the background, a production habitat in the forefront
Dry coolers, for process cooling, an astronaut and a large general purpose vehicle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 01/31/2019 02:35 am
Wow! this thread is chock full of information! Just finished reading through.

So through this threat, has there been any discussion of how/if you can construct Domes from local materials relatively simply? I hadn't spotted anything but may have missed it.

You can make steel and glass from the basic regolith (of varying qualities and quantities) but are they sufficient to do the job? Or would you need to wait until you could produce something more complicated (Aluminium and/or exotic plastics) before you could do it?

Cheers,
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 01/31/2019 03:33 am
I believe steel and glass will be sufficient, with some sealant. So would be steel and plastic panes, with some sealant. There is active debate in various threads about whether glass or plastic is easier to make early on in the ISRU ramp up cycle. In part that depends on how good is good enough for a glass or plastic pane (glass, how impure the silica, plastic, how complex the molecule in the polymer)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/31/2019 04:30 am
Wow! this thread is chock full of information! Just finished reading through.

So through this threat, has there been any discussion of how/if you can construct Domes from local materials relatively simply? I hadn't spotted anything but may have missed it.

You can make steel and glass from the basic regolith (of varying qualities and quantities) but are they sufficient to do the job? Or would you need to wait until you could produce something more complicated (Aluminium and/or exotic plastics) before you could do it?

Cheers,

We just went through a pretty complete analysis of the pros and cons on the following thread:
Elon Musk: glass geodesic domes

https://forum.nasaspaceflight.com/index.php?topic=41526.msg1906319#msg1906319
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 01/31/2019 04:59 am
Wow! this thread is chock full of information! Just finished reading through.

So through this threat, has there been any discussion of how/if you can construct Domes from local materials relatively simply? I hadn't spotted anything but may have missed it.

You can make steel and glass from the basic regolith (of varying qualities and quantities) but are they sufficient to do the job? Or would you need to wait until you could produce something more complicated (Aluminium and/or exotic plastics) before you could do it?

Cheers,

We just went through a pretty complete analysis of the pros and cons on the following thread:
Elon Musk: glass geodesic domes

https://forum.nasaspaceflight.com/index.php?topic=41526.msg1906319#msg1906319

Thanks!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 01/31/2019 04:06 pm
Wow! this thread is chock full of information! Just finished reading through.

So through this threat, has there been any discussion of how/if you can construct Domes from local materials relatively simply? I hadn't spotted anything but may have missed it.

You can make steel and glass from the basic regolith (of varying qualities and quantities) but are they sufficient to do the job? Or would you need to wait until you could produce something more complicated (Aluminium and/or exotic plastics) before you could do it?

Cheers,
Here is another recent thread on a similar topic:
https://forum.nasaspaceflight.com/index.php?topic=47284.0

In summary there is a lot of silica on Mars but the problem will be finding a deposit that is sufficiently close to the landing site that is sufficiently pure. Even small traces of elements like Chromium can turn the glass bottle green. Processing will in all likelihood be very different from the processes used on Earth due to the different gravity, different atmosphere, the shortage of energy and the lack of infrastructure.

Iron and steel can be made by reduction using hydrogen and purified using carbon monoxide. Plastics such as polyethylene and polypropylene and others can be made from water and atmospheric gases (see the above thread for details).

One really big problem will be energy. Some of the processes are really energy intensive for example electrolysis of water to produce hydrogen and oxygen. And these will be in high demand for propellant, for breathing air, for the synthesis of plastics (double the amount of hydrogen is required for the production of ethylene and subsequent plastics) and for the reduction of Iron. The availability of sufficient solar and/or nuclear energy will be the rate determining step in how fast any Mars base can grow.
Title: Re: Envisioning Amazing Martian Habitats
Post by: tea monster on 01/31/2019 09:26 pm
Render of a Mars base using geodesic domes and buried hab units.

The Mars rovers and astronauts are from NASA's 3D assets page.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/01/2019 10:43 pm
A Storm is brewing on Mars
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/02/2019 12:34 am
Regarding landing areas on Mars.  At the rapid development rate suggested by Musk, there will soon be groups of 40 ships moving to Mars every synod.  Seems crazy but at a not to extravagant rate of three ships per year, after 10 year you have 30 ships for Each synod!
How can a Mars base handle the traffic and what might this spaceport like?  What is the spread between ships?  Do they land, fuel and then go straight back up to orbit, so you just have a ship or so at a time?  Do they all arrive the same day?  Same week? Same month?  Do you have half a dozen or more ships on the ground at the same time?
How precise is the landing? 
Do the ships take off from where they landed?
Would a mobile service tower be useful?  Or are they Starships going to be bottom fuelled and so rough and ready that all you need a flat spot and a big set of fill pipes?
How close, or how far, should the prepared propellant tanks be?

Time to design an Amazing spaceport!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/02/2019 02:13 am
Spaceport 1.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/02/2019 03:24 am
Ready to launch.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/03/2019 03:36 am
So after a long discussion on Domes, I've concluded that they are doable, but not very efficient economically.
So I've replaced most of my domes with thick flat tops, with a row of windows for some light, but nothing like a dome.  Here a view of the greenhouse section of my colony.  Mars surface has been removed because it take a long time to render :-)

Dome vs cap.  I think the cap can look good too, if done well.

I'm also looking at some kind of active cooling for the artificially lit greenhouses, since I think they should be well insulated with multilayer insulation, but that also means that they overheat when they are in production mode.  I need a model of forced convection with thin gases over heat exchanger surfaces.  I'm guessing the solution is either equipment with very large surfaces, of very high rpm fans.

Any ideas about Mars spaceports?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/03/2019 02:52 pm
I'd stick with the dome but just concrete over most of it. A hemispherical dome end only requires half the thickness of the same material as a cylinder for the same pressure (ie it has half the stress for the same pressure).

If you make the windows as cupolas, you reduce their radius and therefore the thickness of glass required. Something like Alvernia Studios near Warsaw would be a good design.

(http://www.alvernia.com/wp-content/galleries/about-us/onas.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/03/2019 03:42 pm
What is the CHEAPEST way of getting pressurized volume on mars? Including earth launch of any installed earth-built components but not durable construction equipment or ISRU materials.

Tunnels with some kind of lightweight tunnel liner to ensure a pressure seal despite cracking seems a good contender. Airlocks between sections get imported from earth. Heavier liner is acceptable if it can be produced on mars. What are other cheap options?

The other important point for mars habs is solar power. And by Solar power, I include direct Solar-Thermal as well as Photosynthesys. What is the cheapest way to expand planetary solar usage, given the same restrictions as above? (Including earth launch of any installed earth-built components but not durable construction equipment or ISRU materials.)

Are domes a better or cheaper use of solar energy than algae slush tanks, solar fields, or solar water heaters?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/03/2019 06:10 pm
Two launching pad and two landing pads, with a self propelled transporter used to bring the Starship from the landing zone to the mobile launch platform.
As Starship is probably bottom fed as far as propellant goes, there is no need for a tower.  Although the earlier Starships are supposed to use an internal crane, by the time a spaceport like this one is required what might be the method use to empty out cargo and passengers?

In the background, a fancy dome that serves as the entrance to the colony.

A pair of ISRU build buildings serve as general depots.  What else might be built around a spaceport?
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 02/03/2019 06:28 pm
How does the transporter thingy get under the just landed Starship?

EDIT:  DUH!!!

See next posts following below    VVVV
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 02/03/2019 06:31 pm
How does the transporter thingy get under the just landed Starship?

The same way the octograbber gets under a falcon 9. Three fins/legs should make it easier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/03/2019 06:49 pm
How does the transporter thingy get under the just landed Starship?
It slips under.  The fins raise the Starship about 3m off the ground, plenty of space for a self propelled transporter to slide in.  Then the orange hydraulic jacks lift the starship, perhaps, 1-2m off the ground? by pushing on the hold down points.

 Then the transporter moves the vehicle over to the mobile launch pad.  All the wheels are or turning posts and the system seems very maneuverable.

The illustrated vehicles has 16 x 4 x 2 wheels, or 138 wheels (could have a few more, if needed).  Depending on the load in the Starship, if it is moved to the pad unloaded, that would be about 1 tonne per wheel on Earth, or about 1/3 of that on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/03/2019 07:47 pm
Good looking spaceport.

Even with a concrete or whatever landing pad, FOD (foreign object debris) will be a problem. A dropped bolt, rocks falling off truck wheels, etc. can be propelled at high velocity from the landing rocket exhaust. Could build a berm around the landing pad, but probably would be easier to have a robot remove FOD from the pad. Clean pad, safe landing for nearby equipment.

Just need a supersized Mars Roomba. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2019 02:27 am
Good looking spaceport.

Even with a concrete or whatever landing pad, FOD (foreign object debris) will be a problem. A dropped bolt, rocks falling off truck wheels, etc. can be propelled at high velocity from the landing rocket exhaust. Could build a berm around the landing pad, but probably would be easier to have a robot remove FOD from the pad. Clean pad, safe landing for nearby equipment.

Just need a supersized Mars Roomba. :)
Not much sucking happening at low pressure, but anyway, mechanical brushes and some succion  :-)

And what else might we find at the Mars Spaceport?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/04/2019 12:57 pm
Good looking spaceport.

Even with a concrete or whatever landing pad, FOD (foreign object debris) will be a problem. A dropped bolt, rocks falling off truck wheels, etc. can be propelled at high velocity from the landing rocket exhaust. Could build a berm around the landing pad, but probably would be easier to have a robot remove FOD from the pad. Clean pad, safe landing for nearby equipment.

Just need a supersized Mars Roomba. :)
Not much sucking happening at low pressure, but anyway, mechanical brushes and some succion  :-)

And what else might we find at the Mars Spaceport?

The landing pad should be elliptical because the rocket will have a residual horizontal component as it's coming in to land, unlike on Earth where atmospheric drag cancels out that. NASA's lunar ISRU-derived landing pad concepts are like that. Ideally you want to have only unimportant or very hardened stuff downrange. Being next a crater is good for an overshoot / coming in too hot contingency. Maybe have an emergency pad down there.

Definitely add berms. One Raptor has the power output of Switzerland, even from a long way away is still going to be like a hurricane on Mars - and a flying rock is a good way to wreck another Starship. NASA Human Mission guidelines are for landers to come in at least 5km away from base infrastructure. I would add some kind of deployable netting or screen to protect the ships that have already landed.

Also: a control tower. It will get quite busy, and I imagine there will be loads of small robotic vehicles moving around. Having a room at a good vantage point with big windows is a very good thing, 16K video walls or no. You don't want suddenly be confronted with Windows asking you to update when a Starship is coming in hot. Humans like windows, and if people are monitoring things it gives them that much more confidence. Plus there are just a lot of very mundane uses for a place with windows that's high up.

Sheds for storage. Lights for nighttime illumination. Later on, a big pressurised hangar for shirtsleeve inspections and repair.

Weather and comms station: radar to track and guide incoming Starships, plus up-to-the-minute accurate weather data. There will be quite a few of these downrange.

Beyond that, a lot of pads, two rows going off in alternate directions. This is so that successive ships don't impinge or jostle the ships on the pads underneath their flight track. And in a worst case scenario, ensures one ship doesn't suffer an engine failure and drop right onto another one. Manned ships would land first every synod, then the cargo ships filling in the pads behind them.

You'll still want a berm around the whole thing because the exhaust will pick still impinge on the regolith and send rocks flying.

Last, but not least, a big SpaceX "X" on the landing pad. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/04/2019 01:53 pm
Good looking spaceport.

Even with a concrete or whatever landing pad, FOD (foreign object debris) will be a problem. A dropped bolt, rocks falling off truck wheels, etc. can be propelled at high velocity from the landing rocket exhaust. Could build a berm around the landing pad, but probably would be easier to have a robot remove FOD from the pad. Clean pad, safe landing for nearby equipment.

Just need a supersized Mars Roomba. :)
Not much sucking happening at low pressure, but anyway, mechanical brushes and some succion  :-)

And what else might we find at the Mars Spaceport?
If you have a servicing vehical that drives up to and under a Starship, what about one with an elevator tower that mates with the Starship cargo doors?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/04/2019 02:10 pm
For this year's NASA Big Idea challenge, we have Martian greenhouses!

(Yes, they want you to incorporate translucent-walled inflatables)

http://bigidea.nianet.org/

(http://i2.wp.com/bigidea.nianet.org/wp-content/uploads/2015/09/2-Interior-Rendering-Alternative-1.jpg)

Note the thick restraint webbing, no doubt from much ILC Dover experience. This all sits in a Mars Ice House-type ice structure, filled with water-ice lenses and CO2 pockets for insulation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: tea monster on 02/04/2019 03:11 pm
Fuel and oxidiser tanks, with plenty of thermal shielding. Piping to carry said fuel and oxidiser. Some kind of loading arm to load them into the Starships for launch.

People and cargo carrying vehicles including loading and access arms/elevators.

I personally think that the pads should be further apart as if a ship crashes, it could take out the entire spaceport.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Norm38 on 02/04/2019 03:57 pm
Good looking spaceport.

Even with a concrete or whatever landing pad, FOD (foreign object debris) will be a problem. A dropped bolt, rocks falling off truck wheels, etc. can be propelled at high velocity from the landing rocket exhaust. Could build a berm around the landing pad, but probably would be easier to have a robot remove FOD from the pad. Clean pad, safe landing for nearby equipment.

Just need a supersized Mars Roomba. :)

This is critical, and a point to remember is that the thin martian atmosphere won't do much to decelerate debris once it is flung out.  If shot out like a bullet, it will hit at basically the same velocity that it was launched with.
Title: Re: Envisioning Amazing Martian Habitats
Post by: tea monster on 02/04/2019 07:34 pm
Another thing is that you are going to be moving dozens or hundreds of people off and onto the Starships when they land. Having them all don pressure suits to get into and out of the ship is going to be a pain, and might not work with the young or injured passengers.

Maybe having a vehicle with a pressurised cabin that can be raised on hydraulics up to the hatch of the Starship might be a good idea. It would make a seal with the rocket and the passengers would disembark into the capsule. When the capsule was full, the hatches of the ship and the capsule would be sealed and it would be disconnected from the hatch of the ship. The capsule would then be lowered back onto the flatbed of the vehicle and the passengers would be all rolled over to the main entrance to the colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/04/2019 07:47 pm
Another thing is that you are going to be moving dozens or hundreds of people off and onto the Starships when they land. Having them all don pressure suits to get into and out of the ship is going to be a pain, and might not work with the young or injured passengers.

Maybe having a vehicle with a pressurised cabin that can be raised on hydraulics up to the hatch of the Starship might be a good idea. It would make a seal with the rocket and the passengers would disembark into the capsule. When the capsule was full, the hatches of the ship and the capsule would be sealed and it would be disconnected from the hatch of the ship. The capsule would then be lowered back onto the flatbed of the vehicle and the passengers would be all rolled over to the main entrance to the colony.
Make it big enough for a reasonable sized rover to drive into and be lowered to the ground. Personel can take the elevator when it isn't in use by rovers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2019 07:54 pm
Another thing is that you are going to be moving dozens or hundreds of people off and onto the Starships when they land. Having them all don pressure suits to get into and out of the ship is going to be a pain, and might not work with the young or injured passengers.

Maybe having a vehicle with a pressurised cabin that can be raised on hydraulics up to the hatch of the Starship might be a good idea. It would make a seal with the rocket and the passengers would disembark into the capsule. When the capsule was full, the hatches of the ship and the capsule would be sealed and it would be disconnected from the hatch of the ship. The capsule would then be lowered back onto the flatbed of the vehicle and the passengers would be all rolled over to the main entrance to the colony.
A bit like this one, used in various airport and for the space shuttle, except it goes wayyyyy higher?

http://www.trucktrend.com/features/1707-truck-trend-legends-the-mobile-lounge/

Good for 102 passengers, so just the right size?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2019 08:02 pm
Fuel and oxidiser tanks, with plenty of thermal shielding. Piping to carry said fuel and oxidiser. Some kind of loading arm to load them into the Starships for launch.

People and cargo carrying vehicles including loading and access arms/elevators.

I personally think that the pads should be further apart as if a ship crashes, it could take out the entire spaceport.
Can we expect the Starship to be loaded in propellant from connectors at the base, between the cargo pods, as illustrated in the Dear Moon illustrations?  As well as in the bottom to bottom orbital fueling images?  So a short stump of an arm?

Local tanks good for one fill, plus distant tanks near to the production plant?

Do the really really need to be further away than the pads at Kennedy for Falcon Heavy?  They had 2 'ships' landing at the same time, after all. 
When a ship crashes, it has no more fuel inside... how big a boom will that be?

I would expect that with modern technology we could provide a clean pad for landing.  Can't image there won't be a bolt spotting camera, or rock camera, or whatever of that sort?
Better to solve a problem/risk at the source than to provide a barrier.  Safety 101  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2019 08:03 pm
Another thing is that you are going to be moving dozens or hundreds of people off and onto the Starships when they land. Having them all don pressure suits to get into and out of the ship is going to be a pain, and might not work with the young or injured passengers.

Maybe having a vehicle with a pressurised cabin that can be raised on hydraulics up to the hatch of the Starship might be a good idea. It would make a seal with the rocket and the passengers would disembark into the capsule. When the capsule was full, the hatches of the ship and the capsule would be sealed and it would be disconnected from the hatch of the ship. The capsule would then be lowered back onto the flatbed of the vehicle and the passengers would be all rolled over to the main entrance to the colony.
Make it big enough for a reasonable sized rover to drive into and be lowered to the ground. Personel can take the elevator when it isn't in use by rovers.
Don't quite get this.  A rover in every ship?  Or a rover elevator?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2019 08:09 pm
Landing pad distance: 86 m pads at 310m distance for SpaceX at Kennedy.  Wouldn't this work on Mars as well?

https://en.wikipedia.org/wiki/Landing_Zones_1_and_2

No berms as far as I can see.

Did the Falcon heavy landings generate projectiles?

5 seconds of hurricane winds are not a hurricane.  But I get the point.  However how would it be worse on Mars than on Earth?

Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 02/04/2019 08:38 pm
No assumptions about local geography, such as plain, hills, canyons, or craters are made in the recent posts, except for the launch pads overhanging an escarpment to gain a "flame trench".

An area with varied topography could aid separating several pads, and habitation areas. Unlike on earth, impact on a ship, or HAB structure from a significant piece of shrapnel or displaced rock etc, could easily cause rapid or catastrophic depressurisation, or even collapse, and the death of people within. And rescue of survivors would be slow and cumbersome. It would also cause a setback of colony development.

Therefore it is worth giving protection against such incidents a high priority.
Ideally all pads will be behind a land form, such as a hill, in a valley, round a bend in a canyon, or if these are not available, the pad area could be lowered, and berms/walls created. Any nearby HABs having regolith walls/loose shielding in the pad direction. Any HAB "viewing areas" or "control towers" having pressure doors to isolate each unit.

I suspect "concrete" domes covered by regolith with frequent pressure doors, for radiation reduction, will also reduce any blast risk. And the only way to watch a launch landing directly will be from a pressure suit, or a rover! as nice windows viewing the pads will be banned!
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/04/2019 09:06 pm
Landing pad distance: 86 m pads at 310m distance for SpaceX at Kennedy.  Wouldn't this work on Mars as well?

https://en.wikipedia.org/wiki/Landing_Zones_1_and_2

No berms as far as I can see.

Did the Falcon heavy landings generate projectiles?

5 seconds of hurricane winds are not a hurricane.  But I get the point.  However how would it be worse on Mars than on Earth?

Norm38 pointed it out:

This is critical, and a point to remember is that the thin martian atmosphere won't do much to decelerate debris once it is flung out.  If shot out like a bullet, it will hit at basically the same velocity that it was launched with.

The debris will fly farther in the very thin Mars atmosphere. So, the landing pads need more separation if you're not going to worry about berms or cleaning the pad. Since the launch mount is next to the landing pad, the complex needs enough separation to prevent damage if a BFS blows up on the launch mount.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/04/2019 09:43 pm
Landing pad distance: 86 m pads at 310m distance for SpaceX at Kennedy.  Wouldn't this work on Mars as well?

https://en.wikipedia.org/wiki/Landing_Zones_1_and_2

No berms as far as I can see.

Did the Falcon heavy landings generate projectiles?

5 seconds of hurricane winds are not a hurricane.  But I get the point.  However how would it be worse on Mars than on Earth?

Norm38 pointed it out:

This is critical, and a point to remember is that the thin martian atmosphere won't do much to decelerate debris once it is flung out.  If shot out like a bullet, it will hit at basically the same velocity that it was launched with.

The debris will fly farther in the very thin Mars atmosphere. So, the landing pads need more separation if you're not going to worry about berms or cleaning the pad. Since the launch mount is next to the landing pad, the complex needs enough separation to prevent damage if a BFS blows up on the launch mount.
But if I do clean the pad, as it seems quite logical to do, will we still need berms and distance?  If there are no rocks they can't break anything....

I'm not just arguing for the fun of it, well, perhaps a bit to allow myself to fit two different ship arrangements into a single drawing :-)  but I've based this design on SpaceX's own landing pads so I wonder what is the difference on Mars.  Can we really say that a rock at Kennedy or Vandenberg is less dangerous than on Mars? 

How much damage did the SpaceX pad explosion do?  Quite a bit, I'm sure, but how far did it reach?
On the other hand if a safe distance on Earth is 300m, can I assume the safe distance on Mars will be 1 km, or about three times more? 

Are the multiple pads at Boca Chica yet, BTW?  These would presumably be designed for Spaceship?
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/05/2019 12:59 am
Another thing is that you are going to be moving dozens or hundreds of people off and onto the Starships when they land. Having them all don pressure suits to get into and out of the ship is going to be a pain, and might not work with the young or injured passengers.

Maybe having a vehicle with a pressurised cabin that can be raised on hydraulics up to the hatch of the Starship might be a good idea. It would make a seal with the rocket and the passengers would disembark into the capsule. When the capsule was full, the hatches of the ship and the capsule would be sealed and it would be disconnected from the hatch of the ship. The capsule would then be lowered back onto the flatbed of the vehicle and the passengers would be all rolled over to the main entrance to the colony.
Make it big enough for a reasonable sized rover to drive into and be lowered to the ground. Personel can take the elevator when it isn't in use by rovers.
Don't quite get this.  A rover in every ship?  Or a rover elevator?
An elevator for rovers, which works for passangers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/05/2019 02:20 am
If the self propelled transporter can carry the ship, it can also carry a much lighter mobile tower for disembarking.
A bit of commonality. 
The tower has some hydraulic jacks so the transporter can get under it, then it retracks the jacks so they don't get in the way.
The transporter has  a lounge and an airlock that can connect to rover buses and utility trucks than come and get the passengers and the cargo.  This way the passengers never leave their shirtsleeve environment.
The slowest point is the elevator.  Might take ten to fifteen trips to empty the ship, so perhaps 20 minutes?  The self propelled transporter might be pretty slow as well.

For this to work the Starship hatches must be offset from the fixed fin by about 45 degrees.  Don't know if they are still like that.  They were that way last year but I haven't seen any hatch for a while in the SpaceX models.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/05/2019 02:36 am
A view of the X .  The pads have been separated a bit more, for added safety.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 02/05/2019 05:04 am
After landing, move the Starship to a fixed service tower to unload cargo and passengers before going to the launch cradle for fueling and departure.

The tower can have a pressurised crew access arm leading into elevator/s going straight down to a subway station then off to the colony complex.  Cargo has a separate elevator, un-pressurised, dropping to a loading dock at the base of the tower.

One tower with multiple arms could service 3 or 4 different landing/launch pad sets.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 02/05/2019 02:22 pm
After landing, move the Starship to a fixed service tower to unload cargo and passengers before going to the launch cradle for fueling and departure.

The tower can have a pressurised crew access arm leading into elevator/s going straight down to a subway station then off to the colony complex.  Cargo has a separate elevator, un-pressurised, dropping to a loading dock at the base of the tower.

One tower with multiple arms could service 3 or 4 different landing/launch pad sets.
Kind of like airline gates. Airliners taxi to the gate (usually under their own power but not always) after landing. The carrier presented earlier can do exactly this... move the landed ship to a service tower with an extendable airlock passage way. The only difference from Terra is the height of the arm, and that it seals to the ship
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/05/2019 02:39 pm
After landing, move the Starship to a fixed service tower to unload cargo and passengers before going to the launch cradle for fueling and departure.

The tower can have a pressurised crew access arm leading into elevator/s going straight down to a subway station then off to the colony complex.  Cargo has a separate elevator, un-pressurised, dropping to a loading dock at the base of the tower.

One tower with multiple arms could service 3 or 4 different landing/launch pad sets.
Is it safer to move the ship to the tower or the tower to the ship? That's an endless debate in the making! :-)

Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 02/05/2019 02:51 pm
I like the idea of a mobile launch mount and flame deflector.
There are many pictures of the flame deflectors made of steel in macgregor. They have many pipes welded together at a 45deg angle. They are water cooled which could be a problem for mars. Maybe cool with liquid co2 on mars? We should have lots of that.

Would look like a cross between the mobile stairways for airplanes on earth and the octograbber for f9.
A ship would land on a clean steel or concrete pad.
The mobile launch mount(MLM) would move under the ship.
MLM would then jack up to support ship. (Or ship retracts leg pistons)
Would also provide fuel hookups to ship.
MLM would connect to buried fuel connectors(same as airplanes do today).
Fuel up and launch.
In this way the ship never moves. The stuff for the ship moves to it.

BTW I like the idea of block and tackle and small platform for loading and unloading the Starship.

Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/05/2019 06:40 pm
After landing, move the Starship to a fixed service tower to unload cargo and passengers before going to the launch cradle for fueling and departure.

The tower can have a pressurised crew access arm leading into elevator/s going straight down to a subway station then off to the colony complex.  Cargo has a separate elevator, un-pressurised, dropping to a loading dock at the base of the tower.

One tower with multiple arms could service 3 or 4 different landing/launch pad sets.
Is it safer to move the ship to the tower or the tower to the ship? That's an endless debate in the making! :-)
Put me down for "safer to move the tower to the ship" camp. Even airliners park several diamiters from the facility, and a  mobile gangway makes the final  craft-terminal connection.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 02/05/2019 11:07 pm

Put me down for "safer to move the tower to the ship" camp. Even airliners park several diamiters from the facility, and a  mobile gangway makes the final  craft-terminal connection.
I'm not sure I agree with your analogy or analysis.

Airliners move close to the facility first. Which (except for mobile lounges) does not move at all, only the actual jetbridge moves to close the final gap.  I suspect that we will see something analogous but who knows. Maybe we'll see something more analogous to mobile lounges (but with far higher scissors?)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/06/2019 12:28 am
So with the talk about Space Ports, now would be a good time to interject something I've been thinking about.

Has any one though about using trains on Mars? One benefit this would have is you could ship a relatively light components up from Earth, and build the heavy components locally out of Steel. Just as an example, Half the weight of a 120 tonne Loco, is the wheel set and bogies. And if you build it custom, and fully electic, you could halve the weight again easily. It would make local repair very easy, where as heavy duty trucks may have issues gettting replacement wheels etc.

On top of that, you could have constant access to power using a third rail (as oppose to over-head lines) which would have ALOT less issues on Mars as there won't be any rain or trees to short the track.

Finally, laying track is increasingly becoming VERY automated, and is already very simple. Trains already lend themselve to easy automation.

One big drawback however is how will simple steel fair under the low temperature.

Thoughts?

...I work in the rail industry but am a space nerd, so Mars Trains appelas to me... ;)

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/06/2019 12:46 am
So with the talk about Space Ports, now would be a good time to interject something I've been thinking about.

Has any one though about using trains on Mars? One benefit this would have is you could ship a relatively light components up from Earth, and build the heavy components locally out of Steel. Just as an example, Half the weight of a 120 tonne Loco, is the wheel set and bogies. And if you build it custom, and fully electic, you could halve the weight again easily. It would make local repair very easy, where as heavy duty trucks may have issues gettting replacement wheels etc.

On top of that, you could have constant access to power using a third rail (as oppose to over-head lines) which would have ALOT less issues on Mars as there won't be any rain or trees to short the track.

Finally, laying track is increasingly becoming VERY automated, and is already very simple. Trains already lend themselve to easy automation.

One big drawback however is how will simple steel fair under the low temperature.

Thoughts?

...I work in the rail industry but am a space nerd, so Mars Trains appelas to me... ;)

There was a good discussion that included train here:
https://forum.nasaspaceflight.com/index.php?topic=32636.220


You might get it going again, it's been quiet for a while.
One thing I've been wondering about for Mars is how good the ground connection would be.  Grounding is easy on Earth because the soil is full of dirty water, but permafrost is a poor electrical conductor, so it might be more difficult.  Just a thought.  There was a fair amount of discussion about installing a hyperloop without the need of a tube, since there is a bit of air, there might be enough for a ram effect.  And no one will complain about the noise.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/06/2019 12:53 am
So with the talk about Space Ports, now would be a good time to interject something I've been thinking about.

Has any one though about using trains on Mars? One benefit this would have is you could ship a relatively light components up from Earth, and build the heavy components locally out of Steel. Just as an example, Half the weight of a 120 tonne Loco, is the wheel set and bogies. And if you build it custom, and fully electic, you could halve the weight again easily. It would make local repair very easy, where as heavy duty trucks may have issues gettting replacement wheels etc.

On top of that, you could have constant access to power using a third rail (as oppose to over-head lines) which would have ALOT less issues on Mars as there won't be any rain or trees to short the track.

Finally, laying track is increasingly becoming VERY automated, and is already very simple. Trains already lend themselve to easy automation.

One big drawback however is how will simple steel fair under the low temperature.

Thoughts?

...I work in the rail industry but am a space nerd, so Mars Trains appelas to me... ;)

There was a good discussion that included train here:
https://forum.nasaspaceflight.com/index.php?topic=32636.220


You might get it going again, it's been quiet for a while.
One thing I've been wondering about for Mars is how good the ground connection would be.  Grounding is easy on Earth because the soil is full of dirty water, but permafrost is a poor electrical conductor, so it might be more difficult.  Just a thought.  There was a fair amount of discussion about installing a hyperloop without the need of a tube, since there is a bit of air, there might be enough for a ram effect.  And no one will complain about the noise.

Brilliant! thanks
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/08/2019 05:27 am
So I need some help/thoughts/criticism with four Martian Tunnel designs I've been working on, and I need to Pro/Con them.

Generally:
 - Excuse my use of FEMAP, it's the only thing I've got that I can use easily.
 - All tunnels are roughly the same dimensions, a 3m radius arc, raised 3m off the ground, so 6mx6m in total.
 - Green is ground/martian Regolith
 - Yellow is compacted Regolith
 - Orange is mortar-less, interlocking bricks
 - Internal atmosphere is ~50 kPa, so requires ~6.5m of 2000 kg/m3 (compacted regolith, brick) to counter-act in Martian gravity
 - All dimensions are in Meters
 - no foundation included
 - All tunnels (except 4) will need some kind of sealant, hopefully made locally, but you probably could get away with bringing it from Earth.

Martian Tunnel 1:
Pro:
 - Was my first idea
 - is a "cut and cover" design that only requires you to dig down 7m,
 - Compromises between burying and 'cut and cover'
Con:
 - you have to dig down AND build up
 - Will need to have the below-ground section built and the sides refilled before the above-ground supports can be built

Martian Tunnel 2:
Pro:
 - Basically the same as Tunnel 1
 - But can be built in one go, as the above-ground sides can be built up before the below-ground sides are reburied
Con
 - Would require more earth moved initially for a wider footing
 
Martian Tunnel 3:
Pro:
 - Fully above ground - No Digging!
Con:
 - Needs a very wide base/foundation
 - Access to the top will be difficult, due to height, 13m to the top from ground level (4 stories!, though you can live in 1.5 of them)

Martian Tunnel 4:
Notes:
This design uses an internal steel tank/bladder standing off from the Brick Wall by 50mm (0.05m) to hold the atmosphere, so the tunnel doesn't have to be anywhere near as buried, just some external brick (to make it look cool!) and some dirt for radiation shielding. More stand off distance may be needed to avoid contact with the tunnel wall but the design is basically the same. (Steel tank is in the image, may just be hard to see)
Pro:
 - Much more compact design
 - Can be used for a range of pressures, not limited to 50 kPa
 - provides sealant and insulation
 - Brick won't need to be sealed, and as a result, there is little-to-no risk of damage to the brick structure if the steel tank is punctured (it can leak out from the brick tunnel slowly).
 - Thickness of steel can be adjusted as necessary to make the design very safe
Cons:
 - More complicated design
 - Requires more material
 - Will require corrosion protection for the steel


So that's what I can see so far! Feel free to rip them all to shreds :D


Title: Re: Envisioning Amazing Martian Habitats
Post by: MikeAtkinson on 02/09/2019 06:00 am
This looks interesting. Printed martian habitat.

https://www.youtube.com/watch?v=C_KxqCL5L5Q&feature=youtu.be

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/12/2019 11:08 pm
This looks interesting. Printed martian habitat.

https://www.youtube.com/watch?v=C_KxqCL5L5Q&feature=youtu.be
Interesting and well designed.  Not clear what they use for construction material though, extruded plastic mixed with regolith?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/12/2019 11:24 pm
View towards a node with geodesic dome from a side tunnel.
The artificially lighted one took forever to render.

The rendering tool is very precise, so you can see the difference between a naturally lit sce and one with artificial light.  The loss of light through the dome is set at about 15%.
The orange is probably a bit darker than the real Martian sky would be, but on the other hand the sunlight is at full Earth power so I think this compensates that.
The overall arrangement of a sector is shown in the third image.

Quite similar to the design of Rocket Surgeon, but I've got better tools  ;-)
I would have a bit less that half the base dug in bellow a few meters of regolith and the rest on the surface.

Rocket Surgeon, I suggest you look into the wonders of multilayer insulation for your colony.  Otherwise it might loose heat pretty fast.  https://en.wikipedia.org/wiki/Multi-layer_insulation.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/13/2019 12:22 am
View towards a node with geodesic dome from a side tunnel.
The artificially lighted one took forever to render.

The rendering tool is very precise, so you can see the difference between a naturally lit sce and one with artificial light.  The loss of light through the dome is set at about 15%.
The orange is probably a bit darker than the real Martian sky would be, but on the other hand the sunlight is at full Earth power so I think this compensates that.
The overall arrangement of a sector is shown in the third image.

Quite similar to the design of Rocket Surgeon, but I've got better tools  ;-)
I would have a bit less that half the base dug in bellow a few meters of regolith and the rest on the surface.

Rocket Surgeon, I suggest you look into the wonders of multilayer insulation for your colony.  Otherwise it might loose heat pretty fast.  https://en.wikipedia.org/wiki/Multi-layer_insulation.

Man that looks awesome! Is that just SketchUp? We seem to have similar-ish designs, though I think mine is going to end up being a bit more.... Mesopotamian ;)

Yeah, insulation is definitely something I'm worried about as I'd like to use as many native "ingredients" as possible, hence my idea to use a steel liner stood off a few dozen millimetres from the wall. Same with sealing the tunnels to reduce the loss of atmosphere.

However, I've been having A LOT of problems simulating a non-cylindrical pressure vessel (the stress become literally insane unless I use a perfect circle.. anyone got any good resources/guides for pressure vessel sims?)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/13/2019 12:47 am
View towards a node with geodesic dome from a side tunnel.
The artificially lighted one took forever to render.

The rendering tool is very precise, so you can see the difference between a naturally lit sce and one with artificial light.  The loss of light through the dome is set at about 15%.
The orange is probably a bit darker than the real Martian sky would be, but on the other hand the sunlight is at full Earth power so I think this compensates that.
The overall arrangement of a sector is shown in the third image.

Quite similar to the design of Rocket Surgeon, but I've got better tools  ;-)
I would have a bit less that half the base dug in bellow a few meters of regolith and the rest on the surface.

Rocket Surgeon, I suggest you look into the wonders of multilayer insulation for your colony.  Otherwise it might loose heat pretty fast.  https://en.wikipedia.org/wiki/Multi-layer_insulation.

Man that looks awesome! Is that just SketchUp? We seem to have similar-ish designs, though I think mine is going to end up being a bit more.... Mesopotamian ;)

Yeah, insulation is definitely something I'm worried about as I'd like to use as many native "ingredients" as possible, hence my idea to use a steel liner stood off a few dozen millimetres from the wall. Same with sealing the tunnels to reduce the loss of atmosphere.

However, I've been having A LOT of problems simulating a non-cylindrical pressure vessel (the stress become literally insane unless I use a perfect circle.. anyone got any good resources/guides for pressure vessel sims?)
Sketchup with Twilight render.  Both free versions.
Although I've use non cylindrical pressure vessels in my illustrations I have no adequate way of simulating them either.  And I kind of worry about that.  The only ressources I have are the  approximations for elliptical cylinder ends.  Since domes have half the hoop stress that the cylindrical parts have, it's common practice to flatten the ends, until the thickness required is equal to the thickness of the cylinder walls. 
IF you do come across something I would love to see it!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/13/2019 01:42 am
Here is an annoyingly pessimistic simulation that I've just found regarding pressure vessel sections.  Seems clear the oval section will do everything it can to become a circular section.

Even for very low ovalities they find strains go up practically 50 times.

On the other hand I expect even fairly small external pressure, or internal tension wires would reduce these strains to manageable proportions.

But really, it looks like a bad idea to move away from round.

Damn, will need to redo all the models again :-))  and those curves were so pretty.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/13/2019 03:16 am
Here is an annoyingly pessimistic simulation that I've just found regarding pressure vessel sections.  Seems clear the oval section will do everything it can to become a circular section.

Even for very low ovalities they find strains go up practically 50 times.

On the other hand I expect even fairly small external pressure, or internal tension wires would reduce these strains to manageable proportions.

But really, it looks like a bad idea to move away from round.

Damn, will need to redo all the models again :-))  and those curves were so pretty.

Well, good to see some outside validation of my models.

As a brief simulation, I did a cylinder 6m in diameter and 10m long with an internal pressure of 50 kPa.
Max stress was 30 MPa, so well within the capabilities of the most basic steel.

However, I then made the circle a slight Obround and the stress shot through the roof, up to 1000 MPa at max, which is roughly in line with what that paper showed. I still think there is something wrong in my simulation, but I've hammed my head against it, along with the help of another FEMAP guru and we can't find anything wrong with my model from a simulation perspective. So either it is correct, or there is something fundamentally wrong with my set-up/how I'm processing the results.

I think my steel liner idea is a bust then, or at least not worth the time it would take to develop an optimised shape that can fit in my Archways. Basic reinforcement with steel sections takes a lot less material per unit length. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/13/2019 03:26 am
Here is an annoyingly pessimistic simulation that I've just found regarding pressure vessel sections.  Seems clear the oval section will do everything it can to become a circular section.

Even for very low ovalities they find strains go up practically 50 times.

On the other hand I expect even fairly small external pressure, or internal tension wires would reduce these strains to manageable proportions.

But really, it looks like a bad idea to move away from round.

Damn, will need to redo all the models again :-))  and those curves were so pretty.

Well, good to see some outside validation of my models.

As a brief simulation, I did a cylinder 6m in diameter and 10m long with an internal pressure of 50 kPa.
Max stress was 30 MPa, so well within the capabilities of the most basic steel.

However, I then made the circle a slight Obround and the stress shot through the roof, up to 1000 MPa at max, which is roughly in line with what that paper showed. I still think there is something wrong in my simulation, but I've hammed my head against it, along with the help of another FEMAP guru and we can't find anything wrong with my model from a simulation perspective. So either it is correct, or there is something fundamentally wrong with my set-up/how I'm processing the results.

I think my steel liner idea is a bust then, or at least not worth the time it would take to develop an optimised shape that can fit in my Archways. Basic reinforcement with steel sections takes a lot less material per unit length.
I expect what happens in the real world is plastic deformation until the oval becomes a round shape, or at least until the material can take the strain.  You could probably have an oval shape, as long as the actual structural elements holding it in place were circular.  Barrel hoops, and concrete staves.  Not much point to it though.
You could also have mass pressing down on your archway, that would not need to be structural, just need to balance out the outwards pressure.
Might have awkward results if internal pressure is lost, of course. Having partly self supporting bricks might solve the loss of pressure issue.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/13/2019 03:41 am
Come to think of it, the very nature of a thin walled pressure vessel is that it is so thin it cannot have anything else than tension in it,  there isn't enough thickness for any kind of moment and force to build up.  I guess the lesson is than any vessel thin enough to be a thinned wall pressure vessel will necessarily be circular.

So what about thick walled pressure vessels?  If you have a thin shell under tension (steel) and thick interior under compression (regolith or concrete) because your shape is not circular, does this still create these ridiculous levels of stress?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/13/2019 04:00 am
Come to think of it, the very nature of a thin walled pressure vessel is that it is so thin it cannot have anything else than tension in it,  there isn't enough thickness for any kind of moment and force to build up.  I guess the lesson is than any vessel thin enough to be a thinned wall pressure vessel will necessarily be circular.

So what about thick walled pressure vessels?  If you have a thin shell under tension (steel) and thick interior under compression (regolith or concrete) because your shape is not circular, does this still create these ridiculous levels of stress?

Haven't tried exactly what you suggested above, but upping the wall thickness to 50mm solves the problem...
Problem is you now need 10 tonne of steel per meter of habitat.

Doing what you've described above would take a 'contact' analysis with Solids which would take a while to set up and run unfortunately.

I HAVE tried some basic steel reinforcement simulations and the results are much better, as the reinforcements can be thicker.

...
You could also have mass pressing down on your archway, that would not need to be structural, just need to balance out the outwards pressure.
Might have awkward results if internal pressure is lost, of course. Having partly self supporting bricks might solve the loss of pressure issue.

A while back I did some simulation to check if a Brick Arch could take the required mass to balance an internal atmosphere of ~35 kPa, it can. So the problem isn't designing a compressive Brick Arch to survive a loss of pressure. That's easy.

The problem I found thanks to this thread, is that you can't have an atmosphere that low with out things becoming highly flammable AND still being able to breath (I was using the atmosphere suggested by Bob Zurbin in 'the Case for Mars', 35 kPa and 60% oxygen), and I also used his assumption that regolith would be 4 times as dense as water.

Turns out you need about 7 meters of regolith (with an actual density of ~2000 kg/m3) to counter-act a 45-50 kPa atmosphere. So if you want a Vault about 6 meters high, you need a total structure height of about 15 meters, which needs to be built either totally above ground (tall and difficult to build up 5 stories) or it needs to be partially buried (back to the 'tunnel vs. cut-and-cover vs. above ground' debate).

Hence my "multiple options" a few posts back.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 02/13/2019 04:52 pm
The problems might be greatly reduced if a thick layer of clear ice was formed on top of a flat clear plastic ceiling and the air pressure increased underneath it to support it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 02/13/2019 06:35 pm
The problems might be greatly reduced if a thick layer of clear ice was formed on top of a flat clear plastic ceiling and the air pressure increased underneath it to support it.
Exactly my thought as well -- since water will be part of the ISRU production anyway, why not use it structurally as well?  It has to be easier to make clear ice than glass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/13/2019 08:35 pm
The problems might be greatly reduced if a thick layer of clear ice was formed on top of a flat clear plastic ceiling and the air pressure increased underneath it to support it.
Exactly my thought as well -- since water will be part of the ISRU production anyway, why not use it structurally as well?  It has to be easier to make clear ice than glass.

It gets complicated fast.  Your ice musn't melt, yet it's just a plastic pane away from the hot base.
The ice is going to get dusty.  If these dust grains get a bit hot they will melt into the ice and damage it.
Ice is ridiculously weak structurally and breaks easily under impact.  It might be interesting to go with translucent ice, but again there is a serious risk of overheating the ice.  In summer, after all, certain areas of MArs can get fairly hot.
Ice is not very expensive but the cost of thick ice quickly gets out of hand.  See the joined table.  Glass is 14 times more expensive than ice to manufacture on Mars, plastics are 15 times more expensive than glass.  After all, to make plastic on Mars you need to electrolyse water, or to manage to build Algae farms and do extensive treatment to the biomass.

So if your ice is more than 30 cm thick, compared to small glass panes, it will be more expensive.  And you really need about 20m of ice to offset the pressure of a base at 1 atmosphere. 1 atmosphere is 10 tonnes per m2 of pressure, and as water on Mars weighs only 500 kg per m3...  even at reduced pressures it's ridiculously thick.
It's not impossible, just not, IMHO, a cost effective first solution, or even a first century of occupation solution.  For huge domes it might be applicable.

BTW the table is a compendium of various sources about the intrinsic energy costs of materials.  It a trending way of evaluating construction methods.   The values are far from certain, but give a good idea.  The energy cost if to amortize solar panels on Mars over 20 years with 500$ per kg transportation costs.  Optimistic might be a polite description.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 02/13/2019 08:54 pm
You're probably right for the early habitats, but later on it might have some appeal. I doubt that many of the early habitats would count as amazing in any case. If the upper surface is covered with a thin plastic layer it should be possible to keep the dust out. It would also provide radiation and meteorite protection. Multiple layers of glazing would help insulate the ice from the warm interior.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/13/2019 10:13 pm
The problems might be greatly reduced if a thick layer of clear ice was formed on top of a flat clear plastic ceiling and the air pressure increased underneath it to support it.
Exactly my thought as well -- since water will be part of the ISRU production anyway, why not use it structurally as well?  It has to be easier to make clear ice than glass.

It gets complicated fast.  Your ice musn't melt, yet it's just a plastic pane away from the hot base.
The ice is going to get dusty.  If these dust grains get a bit hot they will melt into the ice and damage it.
Ice is ridiculously weak structurally and breaks easily under impact.  It might be interesting to go with translucent ice, but again there is a serious risk of overheating the ice.  In summer, after all, certain areas of MArs can get fairly hot.
Ice is not very expensive but the cost of thick ice quickly gets out of hand.  See the joined table.  Glass is 14 times more expensive than glass to manufacture on Mars, plastics are 15 times more expensive than glass.  After all, to make plastic on Mars you need to electrolyse water, or to manage to build Algae farms and do extensive treatment to the biomass.

So if your ice is more than 30 cm thick, compared to small glass panes, it will be more expensive.  And you really need about 20m of ice to offset the pressure of a base at 1 atmosphere. 1 atmosphere is 10 tonnes per m2 of pressure, and as water on Mars weighs only 500 kg per m3...  even at reduced pressures it's ridiculously thick.
It's not impossible, just not, IMHO, a cost effective first solution, or even a first century of occupation solution.  For huge domes it might be applicable.

BTW the table is a compendium of various sources about the intrinsic energy costs of materials.  It a trending way of evaluating construction methods.   The values are far from certain, but give a good idea.  The energy cost if to amortize solar panels on Mars over 20 years with 500$ per kg transportation costs.  Optimistic might be a polite description.

Given gravity on Mars is 38% of that on Earth, it'd need to be closer to 27m of water for 1 atmosphere.

Also bare in mind that "clear" ice is about as see-through as water. 27m of water is going to absorb light, making the problem with darkness on Mars even worse... and remember you need to some how build up 27 meters which is basically a 9 storey building, either as a giant tank while the water freezes or lifted into place as specially made 'clear' blocks of ice... and remember that 27 meters doesn't include your living space, so you'd almost certainly have to go higher, or dig deeper.
 
And to be honest, 27,000kg of water per m2 is going to have much better uses on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RobLynn on 02/14/2019 12:02 am
Pretty sure that the basic element of habitat construction on Mars is going to be huge flat stainless steel balloons, laid on slightly dished and flattened ground and then buried under ~10m of dirt before being inflated to create large circular lenticular habitats.  Add a layer of dirt internally to protect floor from damage.
-Lowest manufactured or imported materials input - maybe only a couple of 100 tonnes per hectare.
-Huge internal space to meet psychological need for wide open spaces/vistas and space needed for growing food.
-Good radiation protection and thermal insulation (in fact might even need radiators for cooling).

If someone with a fortune of (say) $20 billion put it into such a habitat then could probably build something on the order of 1km diameter with 50-100million m³ volume to support several thousand inhabitants using $1000/kg imported stainless steel, and all within 20 years of now.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/14/2019 12:50 am
Pretty sure that the basic element of habitat construction on Mars is going to be huge flat stainless steel balloons, laid on slightly dished and flattened ground and then buried under ~10m of dirt before being inflated to create large circular lenticular habitats.  Add a layer of dirt internally to protect floor from damage.
-Lowest manufactured or imported materials input - maybe only a couple of 100 tonnes per hectare.
-Huge internal space to meet psychological need for wide open spaces/vistas and space needed for growing food.
-Good radiation protection and thermal insulation (in fact might even need radiators for cooling).

If someone with a fortune of (say) $20 billion put it into such a habitat then could probably build something on the order of 1km diameter with 50-100million m³ volume to support several thousand inhabitants using $1000/kg imported stainless steel, and all within 20 years of now.
Pressure supported domes are great, until they aren't pressurized anymore. 
Add to this a few tonnes of radiation protection regolith, or ice, per m2, and that become a very dangerous situation indeed.

I agree that probably all colonies will need active cooling.  There's just too much loss when the system go down if they are not properly insulated.  If there is no input, then you need a way to lower your output.  And active cooling can be stopped, not passive cooling.

I've added a calculation for a 1 km stainless steel dome, not pressure balanced.  I find it would need to be about 10 cm thick, and mass about 3 to 4 million tonnes when you include the floor.  At 1000$ per kg that's 2 000 billion dollars.  Plus the metal.
It's a simple calculation but I may be wrong.  Feel free to check.

Title: Re: Envisioning Amazing Martian Habitats
Post by: livingjw on 02/14/2019 01:30 am
So, you are saying that if it loses its air, it collapses? If it loses it air, I don't think the people inside will care.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/14/2019 01:42 am
So, you are saying that if it loses its air, it collapses? If it loses it air, I don't think the people inside will care.
Well yes, if there are tonnes of ice or regolith on it to stop radiation.  Depends if it's a gentle collapse or a catastrophic break.  Stainless steel should be more forgiving than ice, in any case. 
As in any building you hope it is built so that you can detect signs of failure and get out before it collapses.  Limit state design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Eylrid on 02/14/2019 01:46 am
If it rapidly depressurizes the people inside will be dead whether it collapses or not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/14/2019 01:50 am
If it rapidly depressurizes the people inside will be dead whether it collapses or not.
A well designed dome will not collapse rapidly.  It will collapse gracefully.  Or else it is not a well designed dome.
You need an incredibly large hole in a km wide dome to make it collapse quickly. And one of the virtues of steel is its toughness, that makes large failures unlikely.
Not that I think the dome is a good idea.  I'm a tunnel person, with, at most, little domes to gladden the hearts of peppy colonists :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/14/2019 07:49 am
Even for very low ovalities they find strains go up practically 50 times.

At certain locations, yes, but that's kind of a internal shear of the pressure vessel material between inside and outside. Elliptical tank heads are used everywhere. Usually they are overdesigned relative to the cylindrical section anyway because it's a pain to make it a different thickness.

Additonal stress is kinda a good thing for tanks because a tank with two hemispherical heads will experience differential strain at the dome joins... wehen pressurised the cylinder wants to expand more than the domes so you need to account for that with a kind of elbow or just make thick walls and welds.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/14/2019 09:11 am
So, you are saying that if it loses its air, it collapses? If it loses it air, I don't think the people inside will care.

Sure, but if they get to safety during the pressure loss, afterwards they'll want to be able to repair it by simply fixing the hole and repressurising it, not having to replace the entire structure and everything that is crushed under it. So being able to self-support seems a reasonable minimum requirement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 02/14/2019 08:27 pm
So, you are saying that if it loses its air, it collapses? If it loses it air, I don't think the people inside will care.

Sure, but if they get to safety during the pressure loss, afterwards they'll want to be able to repair it by simply fixing the hole and repressurising it, not having to replace the entire structure and everything that is crushed under it. So being able to self-support seems a reasonable minimum requirement.

Large columns of rock put in place when dome is inflated?

Rock cutting should be a basic skill on mars. Might even be better than concrete because the raw materials are cutting cables, diamond saws, torches. All light compared to the materials of concrete. sand(silica) limestone, lots of heat.

So what do people think about cut rock versus poured cement? It seems like cut rock has a lot of advantages?
Native weight instead of imported.
Lower energy to manufacture.

I know in New England we would rather uses cut rock(granite) for curb stones, lighthouses(well not anymore), breakwaters, boat moorings, etc.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/14/2019 08:33 pm
The whole dome idea is looking less and less feasible. Won't be a big loss either: glass domes never were a big hit on Earth, why should they be on Mars. Nice panoramic flat glass windows sure, domes.... well. Seems a bit complicated.

rsdavis9, absolutely agree with you: building with slabs cut out of rock makes a lot of sense. I especially love the interlocking stone courses of lighthouses such as Bell rock: https://www.gracesguide.co.uk/images/4/49/JD_Bell_Rock4.jpg

That would make a lot of sense on Mars, to create guaranteed stable and airtight structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RobLynn on 02/14/2019 09:05 pm
So, you are saying that if it loses its air, it collapses? If it loses it air, I don't think the people inside will care.

I imagine that one of first jobs after inflation would be to make a flat topped basement floor, living, work and industrial space over entire dome area out of a cheap rock based materials (martian masonry) to allow people to escape and move around to do repairs to the thin membrane in the case of a loss of pressure.  Everything above that layer to be easily collapsible.

Or maybe emergency bouncy-castle type air bag mushrooms that can be inflated rapidly in case of loss of pressure to support entire roof.

Or maybe cover dome in vast array of hexagonal water tanks that can be drained quickly to a reservoir to remove the weight.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 02/14/2019 09:36 pm
The problems might be greatly reduced if a thick layer of clear ice was formed on top of a flat clear plastic ceiling and the air pressure increased underneath it to support it.
Exactly my thought as well -- since water will be part of the ISRU production anyway, why not use it structurally as well?  It has to be easier to make clear ice than glass.

It gets complicated fast.  Your ice musn't melt, yet it's just a plastic pane away from the hot base.
The ice is going to get dusty.  If these dust grains get a bit hot they will melt into the ice and damage it.
Ice is ridiculously weak structurally and breaks easily under impact.  It might be interesting to go with translucent ice, but again there is a serious risk of overheating the ice.  In summer, after all, certain areas of MArs can get fairly hot.
Ice is not very expensive but the cost of thick ice quickly gets out of hand.  See the joined table.  Glass is 14 times more expensive than glass to manufacture on Mars, plastics are 15 times more expensive than glass.  After all, to make plastic on Mars you need to electrolyse water, or to manage to build Algae farms and do extensive treatment to the biomass.

So if your ice is more than 30 cm thick, compared to small glass panes, it will be more expensive.  And you really need about 20m of ice to offset the pressure of a base at 1 atmosphere. 1 atmosphere is 10 tonnes per m2 of pressure, and as water on Mars weighs only 500 kg per m3...  even at reduced pressures it's ridiculously thick.
It's not impossible, just not, IMHO, a cost effective first solution, or even a first century of occupation solution.  For huge domes it might be applicable.

BTW the table is a compendium of various sources about the intrinsic energy costs of materials.  It a trending way of evaluating construction methods.   The values are far from certain, but give a good idea.  The energy cost if to amortize solar panels on Mars over 20 years with 500$ per kg transportation costs.  Optimistic might be a polite description.

Given gravity on Mars is 38% of that on Earth, it'd need to be closer to 27m of water for 1 atmosphere.

Also bare in mind that "clear" ice is about as see-through as water. 27m of water is going to absorb light, making the problem with darkness on Mars even worse... and remember you need to some how build up 27 meters which is basically a 9 storey building, either as a giant tank while the water freezes or lifted into place as specially made 'clear' blocks of ice... and remember that 27 meters doesn't include your living space, so you'd almost certainly have to go higher, or dig deeper.
 
And to be honest, 27,000kg of water per m2 is going to have much better uses on Mars.

Yes all true, but that’s worse case. It may not be desirable to have 1 atmosphere of pressure and the ice does not have to carry the entire pressure on its own as I imagine a significant steel structure would still be needed. Even a few metres of ice would help as a radiation shield and aid in the strength of the structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 02/15/2019 12:32 am
Inflate your dome underneath a rigid spider web of steel bands.  Once in the right position, attach the dome material to the steel with some form of adhesive overstraps glued to the material on either side of a steel member.
This should allow some slight movement due to pressure variations but prevent a full collapse in the case of pressure loss.

Over the top of the steel frame goes multiple layers of clear poly something or other to act as mmod and radiation protection.  Seal the bottom layer/s to the dome material to give an air gap for insulation purposes. When the top gets too dusty just replace the top layer with a fresh, clean one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/15/2019 08:39 am
to act as mmod and radiation protection.

You don't need MMOD protection on Mars. Micrometeors can't reach the ground, only larger ones.

Inflate your dome

Domes are the wrong shape for a pressure vessel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Semmel on 02/15/2019 09:46 am
How about:
Use curved glass plates that follow the outward curvature, but cover it on the outside with thin wire mesh. These are mounted to beams just as shown before. The trick of the wire mesh on the outside of the windows is, that they take all the tensile forces that the glass cant resist. It would look ugle up close but if you are a few meters away, the mesh would hardly be visible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/15/2019 10:44 am
to act as mmod and radiation protection.

You don't need MMOD protection on Mars. Micrometeors can't reach the ground, only larger ones.

Inflate your dome

Domes are the wrong shape for a pressure vessel.
Wrong on the second part. In fact, if you have only radial reinforcement, a dome (of a specific type) is the ideal shape for a pressure vessel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/15/2019 02:50 pm
Just a reminder that if we want to discuss the nitty gritty of transparent domes etc there's a whole thread dedicated to that.

In general, I think balancing internal pressure with external mass is a recipe for disaster.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/15/2019 04:23 pm
Just a reminder that if we want to discuss the nitty gritty of transparent domes etc there's a whole thread dedicated to that.

In general, I think balancing internal pressure with external mass is a recipe for disaster.
As long as the external mass forms stable arches when unpressurized, I don't see the issue.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 02/15/2019 08:32 pm
This probably deserves its own thread, but meet Marsha:

https://m.youtube.com/watch?v=XnrVV0w2jrE#


This reminds me of the Scottish Brochs:
https://www.thevintagenews.com/2017/04/15/the-broch-of-mousa-is-the-best-preserved-iron-age-broch-in-scotland/
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 02/15/2019 10:36 pm
Marsha seems well thought out, especially if there’s a good 3D printer extrudable material that can be locally sourced without too much equipment transport. IDK how much infrastructure/other resources might be required for PLA. Biological production means it competes with food.

It would be nice to include some discussion of adding tunnels to connect these structures through the basement so as a settlement develops and there are more of them, people don’t have to go outside to travel between them. Design wise they do a nice job of creating a light airy sort of interior with natural sunlight while still dealing with pressure vessel and construction constraints.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/15/2019 11:17 pm
Come to think of it, the very nature of a thin walled pressure vessel is that it is so thin it cannot have anything else than tension in it,  there isn't enough thickness for any kind of moment and force to build up.  I guess the lesson is than any vessel thin enough to be a thinned wall pressure vessel will necessarily be circular.

So what about thick walled pressure vessels?  If you have a thin shell under tension (steel) and thick interior under compression (regolith or concrete) because your shape is not circular, does this still create these ridiculous levels of stress?

Haven't tried exactly what you suggested above, but upping the wall thickness to 50mm solves the problem...
Problem is you now need 10 tonne of steel per meter of habitat.

Doing what you've described above would take a 'contact' analysis with Solids which would take a while to set up and run unfortunately.

I HAVE tried some basic steel reinforcement simulations and the results are much better, as the reinforcements can be thicker.

...
You could also have mass pressing down on your archway, that would not need to be structural, just need to balance out the outwards pressure.
Might have awkward results if internal pressure is lost, of course. Having partly self supporting bricks might solve the loss of pressure issue.

A while back I did some simulation to check if a Brick Arch could take the required mass to balance an internal atmosphere of ~35 kPa, it can. So the problem isn't designing a compressive Brick Arch to survive a loss of pressure. That's easy.

The problem I found thanks to this thread, is that you can't have an atmosphere that low with out things becoming highly flammable AND still being able to breath (I was using the atmosphere suggested by Bob Zurbin in 'the Case for Mars', 35 kPa and 60% oxygen), and I also used his assumption that regolith would be 4 times as dense as water.

Turns out you need about 7 meters of regolith (with an actual density of ~2000 kg/m3) to counter-act a 45-50 kPa atmosphere. So if you want a Vault about 6 meters high, you need a total structure height of about 15 meters, which needs to be built either totally above ground (tall and difficult to build up 5 stories) or it needs to be partially buried (back to the 'tunnel vs. cut-and-cover vs. above ground' debate).

Hence my "multiple options" a few posts back.
For oval tunnels, I think the solution is to have the tunnel made from a combination of circular arches with 'knuckle joint at each direction change.  The thin walled pressure vessel behaves exactly like a cable.  It can only handle forces in a single direction, hence that is why the hoop stress equation is only normal: it transforms the radial pressure into a normal force in the thin wall. That is why it fails in a numerical simulation.  You are trying to use the cable to resist a moment, and it is totally incapable of it.
You can model the pressure vessel wall analytically as a series of square cables.  A change in direction of one of these cables corresponds to having it turn on a pulley wheel.   The strain in the cable remains the same but the force on the pulley varies with the angle.
The tunnel liners serve as the 'pulleys' and the exterior walls are the 'cable'.  For a 15 degree angle change, for example, the walls will need to handle the couple induced by cos 15%, about 25% of the normal force.  And this will be a compressive force, so if you have a fairly thick regolith liner inside the pressure wall you can survive the angle change. 
I think I've just saved my non circular tunnels.  Hope I am right.  Any thought on this?

Might be the best way to model anchors in a base plate for a 'dome on a plate' design, as well. The reinforcing rods in the plate concrete act as more cables, compressing the plate amd linking the walls together.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/16/2019 03:26 am
Here's part two.

https://www.youtube.com/watch?v=C_KxqCL5L5Q
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/16/2019 04:59 am
Here's part two.

https://www.youtube.com/watch?v=C_KxqCL5L5Q

I love the looks of these! They remind me of the Stone Towers from Majora's Mask

My one concern is that in their current form, they wouldn't scale well to hundreds or thousands of people in terms of mass brought from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 02/16/2019 09:28 am
Come to think of it, the very nature of a thin walled pressure vessel is that it is so thin it cannot have anything else than tension in it,  there isn't enough thickness for any kind of moment and force to build up.  I guess the lesson is than any vessel thin enough to be a thinned wall pressure vessel will necessarily be circular.

So what about thick walled pressure vessels?  If you have a thin shell under tension (steel) and thick interior under compression (regolith or concrete) because your shape is not circular, does this still create these ridiculous levels of stress?

Haven't tried exactly what you suggested above, but upping the wall thickness to 50mm solves the problem...
Problem is you now need 10 tonne of steel per meter of habitat.

Doing what you've described above would take a 'contact' analysis with Solids which would take a while to set up and run unfortunately.

I HAVE tried some basic steel reinforcement simulations and the results are much better, as the reinforcements can be thicker.

...
You could also have mass pressing down on your archway, that would not need to be structural, just need to balance out the outwards pressure.
Might have awkward results if internal pressure is lost, of course. Having partly self supporting bricks might solve the loss of pressure issue.

A while back I did some simulation to check if a Brick Arch could take the required mass to balance an internal atmosphere of ~35 kPa, it can. So the problem isn't designing a compressive Brick Arch to survive a loss of pressure. That's easy.

The problem I found thanks to this thread, is that you can't have an atmosphere that low with out things becoming highly flammable AND still being able to breath (I was using the atmosphere suggested by Bob Zurbin in 'the Case for Mars', 35 kPa and 60% oxygen), and I also used his assumption that regolith would be 4 times as dense as water.

Turns out you need about 7 meters of regolith (with an actual density of ~2000 kg/m3) to counter-act a 45-50 kPa atmosphere. So if you want a Vault about 6 meters high, you need a total structure height of about 15 meters, which needs to be built either totally above ground (tall and difficult to build up 5 stories) or it needs to be partially buried (back to the 'tunnel vs. cut-and-cover vs. above ground' debate).

Hence my "multiple options" a few posts back.
For oval tunnels, I think the solution is to have the tunnel made from a combination of circular arches with 'knuckle joint at each direction change.  The thin walled pressure vessel behaves exactly like a cable.  It can only handle forces in a single direction, hence that is why the hoop stress equation is only normal: it transforms the radial pressure into a normal force in the thin wall. That is why it fails in a numerical simulation.  You are trying to use the cable to resist a moment, and it is totally incapable of it.
You can model the pressure vessel wall analytically as a series of square cables.  A change in direction of one of these cables corresponds to having it turn on a pulley wheel.   The strain in the cable remains the same but the force on the pulley varies with the angle.
The tunnel liners serve as the 'pulleys' and the exterior walls are the 'cable'.  For a 15 degree angle change, for example, the walls will need to handle the couple induced by cos 15%, about 25% of the normal force.  And this will be a compressive force, so if you have a fairly thick regolith liner inside the pressure wall you can survive the angle change. 
I think I've just saved my non circular tunnels.  Hope I am right.  Any thought on this?

Might be the best way to model anchors in a base plate for a 'dome on a plate' design, as well. The reinforcing rods in the plate concrete act as more cables, compressing the plate amd linking the walls together.
I think having martian regolith with a mass of 4x that of water is a bit excessive. perhaps half of that IMHO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Luc on 02/16/2019 09:44 am
Rather than build tunnels between them, why not simply build the adjacent to one another? Seems much more efficient.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Aussie_Space_Nut on 02/16/2019 09:56 am
The video's show various fittings & windows being embedded within the walls while building. In a similar way, if you were to use a generous amount of goop, I wonder if you could use local stone in the walls as well? I don't mean like a brick wall with thin mortar, but much thicker mortar so the wall can still flex.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/16/2019 11:02 am
Re: Marsha

My one concern is that in their current form, they wouldn't scale well to hundreds or thousands of people in terms of mass brought from Earth.

As near as I can tell, they aren't really sufficient to perform the tasks needed in their own creation. That is, they are the small living section off of the settlement-proper, not the primary settlement themselves. Suitable, perhaps, for a small NASA hab. Not suitable for a settlement.

Like a lot of these designs, it focuses on the human living area (with some token lab and green space). Given the requirements for agriculture, industry, etc, needed to support people, the actual "housing" itself will be a rounding-off error.



Rather than build tunnels between them, why not simply build the adjacent to one another? Seems much more efficient.

Mutual shadowing becomes an issue.

And if you don't care about that, then you don't need the height and could instead build long. Continuous sausages.

(Their justification for the shape was by comparing it against a dome. And obviously it'll work better than a dome.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/16/2019 11:03 am
Domes are the wrong shape for a pressure vessel.
Wrong on the second part. In fact, if you have only radial reinforcement, a dome (of a specific type) is the ideal shape for a pressure vessel.

See a few pages back regarding the relationship between radius of curve and strength requirements. A dome would transmit all the forces around it to the joint with its edge. You are taking a sphere, a perfectly good pressure holding shape, and cutting through every line of force. It has to go somewhere.



suggested by Bob Zurbin in 'the Case for Mars', [...] I also used his assumption that regolith would be 4 times as dense as water.

Compacted sand has a given density of around 1.7 tonnes/m³, loose sand around 1.4. (Wet rammed sand is about 2.1 t/m³, I suspect polymer-regolith in 3d printing is less.) Cured cement is around 3 tonnes/m³. Even solid basalts or granites are around 3. Not sure where Zubrin ever got 4 tonnes/m³. (Which is why I never trust any figures produced by Zubrin, or Zubrin fans. Even his most "conservative" figures are always over-inflated.)

Mars regolith is usually given at 1500kg/m³, putting it in the same range as ordinary sand. So compacted or sintered into blocks, it'll be around 2. If Marscrete has the same density as Portland, you can assume 3 if you have well produced inputs, 2.5 for early stuff that's more porous and imprecise. Iron or steel is around 8 tonnes/m³, electrically/RF sintered metal fines will be around 2.5-4 depending on how much you can compact them while sintering.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/16/2019 11:36 am
Domes are the wrong shape for a pressure vessel.
Wrong on the second part. In fact, if you have only radial reinforcement, a dome (of a specific type) is the ideal shape for a pressure vessel.

See a few pages back regarding the relationship between radius of curve and strength requirements. A dome would transmit all the forces around it to the joint with its edge. You are taking a sphere, a perfectly good pressure holding shape, and cutting through every line of force. It has to go somewhere.



suggested by Bob Zurbin in 'the Case for Mars', [...] I also used his assumption that regolith would be 4 times as dense as water.

Compacted sand has a given density of around 1.7 tonnes/m³, loose sand around 1.4. (Wet rammed sand is about 2.1 t/m³, I suspect polymer-regolith in 3d printing is less.) Cured cement is around 3 tonnes/m³. Even solid basalts or granites are around 3. Not sure where Zubrin ever got 4 tonnes/m³. (Which is why I never trust any figures produced by Zubrin, or Zubrin fans. Even his most "conservative" figures are always over-inflated.)

Mars regolith is usually given at 1500kg/m³, putting it in the same range as ordinary sand. So compacted or sintered into blocks, it'll be around 2. If Marscrete has the same density as Portland, you can assume 3 if you have well produced inputs, 2.5 for early stuff that's more porous and imprecise. Iron or steel is around 8 tonnes/m³, electrically/RF sintered metal fines will be around 2.5-4 depending on how much you can compact them while sintering.

Yeah, I have since found this myself. Though the number varies, I tend to use 2000 kg/m3 as the base line density for anything used to bury my vaults. You could do better if you found some thing like a Lead deposit, but 2000 kg/m3 is roughly what you can do with what is literally lying around.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 02/16/2019 05:31 pm
Rather than build tunnels between them, why not simply build the adjacent to one another? Seems much more efficient.

Yep. If you put them close together it’s easy to just link the bottom levels with short surface tubes. They depict them spread far apart for no apparent reason.

Over longer distances, underground tunnels might be more efficient since they might be built by Tunnel Boring Machines that use only local materials that are readily available. The habs are 3D printed from extruded plastic that requires agriculture and would compete with food for resources.

I suppose that’s an issue with these habs in general vs underground construction or use of some sort of locally sourced concrete (geo/areopolymer?). The plastic material they’re made with seems to be a bottleneck.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 02/17/2019 05:54 pm
Lets say that you are sick of being confined to the cramped Spaceship with other annoying colonists all the time, so you have used a simple roadheader to excavate a nice set of underground tunnels. They are at a comfortable depth of 10+ meters, and even have buried airlocks at the entrance so that they can be pressurized.

Now how would you go about lining the walls of the tunnels? Without having to import lots of mass from Earth or manufacture huge amounts of Martian concrete or bricks.

What I am imagining is a machine that would press on the wall of the tunnel to compact it and then deliver either heat or microwaves to sinter it for good measure.

Thoughts?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 02/17/2019 06:09 pm
Lets say that you are sick of being confined to the cramped Spaceship with other annoying colonists all the time, so you have used a simple roadheader to excavate a nice set of underground tunnels. They are at a comfortable depth of 10+ meters, and even have buried airlocks at the entrance so that they can be pressurized.

Now how would you go about lining the walls of the tunnels? Without having to import lots of mass from Earth or manufacture huge amounts of Martian concrete or bricks.

What I am imagining is a machine that would press on the wall of the tunnel to compact it and then deliver either heat or microwaves to sinter it for good measure.

Thoughts?

Would have thought you want to be deeper than 10M. Not sure how deep but you want to be well into the solid bed rock not the regolith or fracture zone. So no need to compact  the walls of the tunnel.

Once bored I would fill any residual fissures or cracks with cement (preferably made on Mars) Then coat the whole tunnel surface with a thin layer of polythene (manufactured on Mars) to make it totally air tight.

The only issue then is heat. Might also need to have an insulation layer to prevent excessive heat loss to the ground
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/17/2019 06:44 pm
Might be the best way to model anchors in a base plate for a 'dome on a plate' design, as well. The reinforcing rods in the plate concrete act as more cables, compressing the plate amd linking the walls together.

Just to reiterate, spherical or circular pressure vessels are nice for rigid pressure vessels, but not necessary. The space shuttle cabin didn't bother with domed bulkheads or anything. They were flat. The Orion forward bulkhead is flat. Kibo's end is flat, so is the ELPM connected to it. An 8m diameter tunnel made of steel-lined marscrete is not going to explode. It's only where we propose things like locally-produced glass that pressure vessels should be rounded. Before its demise, the X-33 program was looking at flat-sided conformal tanks to make the most out of its rounded rectangular cross-section. And those tanks would be super light, have to carry launch loads and be pressurised to 2-3 bar. For reference, it was the multi-lobed composite cryo tanks that failed.

But if you're making an inflatable dome then the bottom needs to have some sort of roundness to it otherwise it tries to become a sphere. But you can flatten the bottom somewhat with restraint straps and so on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/17/2019 06:53 pm
Lets say that you are sick of being confined to the cramped Spaceship with other annoying colonists all the time, so you have used a simple roadheader to excavate a nice set of underground tunnels. They are at a comfortable depth of 10+ meters, and even have buried airlocks at the entrance so that they can be pressurized.

Now how would you go about lining the walls of the tunnels? Without having to import lots of mass from Earth or manufacture huge amounts of Martian concrete or bricks.

What I am imagining is a machine that would press on the wall of the tunnel to compact it and then deliver either heat or microwaves to sinter it for good measure.

Thoughts?

Microwaves only really work on lunar soil because of the nanophase iron in the regolith (which would not apply since you're talking about a roadheader which would only make sense well below the regolith anyway). Raw heat needs to be applied on Mars, through susceptor-assisted microwaves perhaps. But sintered melts would not seal well - they're full of cracks and bubbles. Glassy materials need a long time to cool to prevent cracking. You could make bricks of it offsite.

To prepare opaque glass and glass fibres from lunar or Martian regolith is not difficult. Something more sophisticated may be needed, such as a TBM that creates a glass fibre tunnel liner as it goes that is used to reinforce something like the sulphur-based concrete they've been testing.

https://www.researchgate.net/publication/329054230_Manufacture_of_glass_and_mirrors_from_lunar_regolith_simulant
https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=2428&context=matsci_eng_facwork

I have seen a suggestion for a regolith-tunneling machine based on melting and solidifying the tunnel walls, which would work quite easily since in most places the first 5 to 20m of Martian surface is just loose dust.

But personally I'm not a fan of underground tunnels as Martian habitats, not on their own anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/17/2019 11:01 pm
The Orion forward bulkhead is flat.

Actually it's a slight curve, around a foot IIRC. (But that's to do with the shape of the heat-shield, I suspect.)

So are the ends of Kibo's pressure vessel. The flat plate is the MMOD shield. There's a gap between that and the pressure-vessel proper, you can see it on some of the construction images.

Nonetheless, regarding this and your similar comment in t'other thread: You don't see a slight difference between a couple of square metres and hundreds? Between a few tens of tonnes of force and a few thousand tonnes of force?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/18/2019 08:09 am
Lets say that you are sick of being confined to the cramped Spaceship with other annoying colonists all the time, so you have used a simple roadheader to excavate a nice set of underground tunnels. They are at a comfortable depth of 10+ meters, and even have buried airlocks at the entrance so that they can be pressurized.

Now how would you go about lining the walls of the tunnels? Without having to import lots of mass from Earth or manufacture huge amounts of Martian concrete or bricks.

What I am imagining is a machine that would press on the wall of the tunnel to compact it and then deliver either heat or microwaves to sinter it for good measure.

Thoughts?

...
I have seen a suggestion for a regolith-tunneling machine based on melting and solidifying the tunnel walls, which would work quite easily since in most places the first 5 to 20m of Martian surface is just loose dust.

But personally I'm not a fan of underground tunnels as Martian habitats, not on their own anyway.

Do you have a source for this? I just want to be able to confirm this for my own designs for both building and manufacturing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/18/2019 10:50 am
The Orion forward bulkhead is flat.

Actually it's a slight curve, around a foot IIRC. (But that's to do with the shape of the heat-shield, I suspect.)

So are the ends of Kibo's pressure vessel. The flat plate is the MMOD shield. There's a gap between that and the pressure-vessel proper, you can see it on some of the construction images.

Nonetheless, regarding this and your similar comment in t'other thread: You don't see a slight difference between a couple of square metres and hundreds? Between a few tens of tonnes of force and a few thousand tonnes of force?

Orion's forward bulkhead.

Required thickness is directly proportional to radial, so scaling up a pressure vessel is quite an easy thing. My main point is that you don't have to have curved cross sections everywhere if you really don't want to. Some parts can be flat, they just need extra reinforcement. I would go for a beveled section below the barrel connecting to a flat base plate. In the context of 8m diameter tunnels, I think flat bottoms are quite manageable.

For an actual worked example of a flat-bottomed dome, see page 35 of this article. (Their dome is 38m in diameter, concrete and uses pre-stressing cables and anchors driven into the ground to deal with the upward pressure).

https://www.researchgate.net/publication/318792953_Earthrise_I_Design_of_a_Stripmining_Base_on_the_Moon

4th year civil engineering students doing a project certainly beats out my limited knowledge.

...
I have seen a suggestion for a regolith-tunneling machine based on melting and solidifying the tunnel walls, which would work quite easily since in most places the first 5 to 20m of Martian surface is just loose dust.

But personally I'm not a fan of underground tunnels as Martian habitats, not on their own anyway.

Do you have a source for this? I just want to be able to confirm this for my own designs for both building and manufacturing.

All I can find on the topic is this: https://www.lpi.usra.edu/publications/reports/TR98-01/98-01.full.pdf

See page 2. Due to nanophase iron it would be easier to microwave-sinter regolith into a 1cm thick shell on the Moon. Mars would require direct heating and possibly glassing the regolith. The trouble with glass is the amount of time it takes to cool without cracking. They suggest using a metal plasma spray gun to seal the cracks... but cracks in glass can show up months later. Also note the enormous power requirements: 500kW thermal energy for a 3m diameter hole, from a nuclear reactor. Very supervillain-ish.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/18/2019 03:32 pm
Some parts can be flat, they just need extra reinforcement. [...] and uses pre-stressing cables and anchors driven into the ground to deal with the upward pressure).

And this has always been my point. It's not that it's "impossible", it's that once you add the extra engineering required to deal with the shape... why are you insisting on that shape again? People propose this stuff because they think it's "easier", "just inflate a dome" (even better, a dome over open ground), and then you have the tail-chase of adding all the things you need in order to make it actually work, but by then you've stopped (or never started) looking at alternatives that might be vastly superior.

The MARSHA proposal is an example (although the opposite conclusion), they examined the forces on their structure vs a dome and of course their structure won out. But then they stopped. A dome was assumed to be the "best" solution to compare it to, rather than one of the worst.

[Aside: The report you linked to is the same. The author chose a surface dome because of aesthetic reasons, then "solved" the issues caused by that choice without analysing any other option. Also He3 mining?]



That said, tunnels are a little different. You've dealing with pressure from the rock/regolith not only above you, but also alongside you, it changes the places you can transfer force to. Also, even the weight on the ceiling is not just the rock/regolith above the tunnel that is pushing down, it's the rock/regolith which is able to transfer force to that. (See sketch below.) The angle (red lines) depends on the friction/cohesion of the rock/regolith. Same way rock anchors work, they aren't just pulling on the rock they are touching, but on the rock being pulled by that rock, etc, created an inverted cone. (In the case of lose material, it might be related to the angle-of-repose?)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/18/2019 10:38 pm
Thought you all might enjoy some images of production areas rather than the usual living spaces.

Raw material treatment, mostly. 

Raw material sourcing
Steel melting and extrusion
Steel wires (similar process)
Glass making
3D printers
And oil distillation
Input on details and such would be great!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 02/19/2019 02:23 am
Lets say that you are sick of being confined to the cramped Spaceship with other annoying colonists all the time, so you have used a simple roadheader to excavate a nice set of underground tunnels. They are at a comfortable depth of 10+ meters, and even have buried airlocks at the entrance so that they can be pressurized.

Now how would you go about lining the walls of the tunnels? Without having to import lots of mass from Earth or manufacture huge amounts of Martian concrete or bricks.

What I am imagining is a machine that would press on the wall of the tunnel to compact it and then deliver either heat or microwaves to sinter it for good measure.

Thoughts?

Would have thought you want to be deeper than 10M. Not sure how deep but you want to be well into the solid bed rock not the regolith or fracture zone. So no need to compact  the walls of the tunnel.

Once bored I would fill any residual fissures or cracks with cement (preferably made on Mars) Then coat the whole tunnel surface with a thin layer of polythene (manufactured on Mars) to make it totally air tight.

The only issue then is heat. Might also need to have an insulation layer to prevent excessive heat loss to the ground

It ought to be possible locally make aerogel with methanol and liquid CO2 that’s a fantastic insulator.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/19/2019 08:47 am
Lets say that you are sick of being confined to the cramped Spaceship with other annoying colonists all the time, so you have used a simple roadheader to excavate a nice set of underground tunnels. They are at a comfortable depth of 10+ meters, and even have buried airlocks at the entrance so that they can be pressurized.

Now how would you go about lining the walls of the tunnels? Without having to import lots of mass from Earth or manufacture huge amounts of Martian concrete or bricks.

What I am imagining is a machine that would press on the wall of the tunnel to compact it and then deliver either heat or microwaves to sinter it for good measure.

Thoughts?

Would have thought you want to be deeper than 10M. Not sure how deep but you want to be well into the solid bed rock not the regolith or fracture zone. So no need to compact  the walls of the tunnel.

Once bored I would fill any residual fissures or cracks with cement (preferably made on Mars) Then coat the whole tunnel surface with a thin layer of polythene (manufactured on Mars) to make it totally air tight.

The only issue then is heat. Might also need to have an insulation layer to prevent excessive heat loss to the ground

It ought to be possible locally make aerogel with methanol and liquid CO2 that’s a fantastic insulator.
Even when you melt the rock you don't change the volume, so you can't really 'press' it into the walls.  If you have sandstone, some types have a lot of voids, and you could probably densify it significantly by melting it.  You end up with glass, which is not the strongest material and very susceptible to fracture shock and catastrophic failure.  You might want to make glass blocks, in that way the fractures are controlled.  You just need to fill the gap between the blocks with suitable flexible material.

Alternatively, if you find a suitable source of calcium carbonate, or of you develop a suitable process for magnesium carbonate, or if you feel comfortable with cement that can burn (sulfur based binders), you have three ways of producing cement, that you can use to bind the stone from the tunnel into concrete elements or compressed regolith elements.
For insulation, I suggest multilayer insulation (see Wikipedia).  It is used extensively in satellites and cryogenics, and is both extremely effective, and light.  If you have a plastics industry than can produce thin films , then you can produce it locally. 
You want to be in bedrock if you want to use the tunnel walls as pressure holding structure.  If you use the tunnel liner as the pressure holding structure then the tunnel can easily be in fractured surface regolith.  Easier to dig.
Bedrock will be fractured anyway.  But less than surface rock.
See joined file for pressure tunnel liner ideas
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/19/2019 01:20 pm
---
The MARSHA proposal is an example (although the opposite conclusion), they examined the forces on their structure vs a dome and of course their structure won out. But then they stopped. A dome was assumed to be the "best" solution to compare it to, rather than one of the worst.


Pretty much all of the NASA 3D Print Hab entrants proposed a dome with a flat base. MARSHA is a skinny dome to cut down on the footprint when printing and to tower above the Martian landscape providing a good view. Personally I think they have far too little radiation shielding in the design. My personal favourite is SEArch+/Apis Corp's entry, which is slightly buried.

https://www.nasa.gov/directorates/spacetech/centennial_challenges/3DPHab/top-10-virtual-model-stage

The competition is in Phase 3 now, with testing of actual structures. Recently they did 3D printed structure pressure testing, which is awesome and solves a lot of the problems we've been stuck with.

Quote
That said, tunnels are a little different. You've dealing with pressure from the rock/regolith not only above you, but also alongside you, it changes the places you can transfer force to. Also, even the weight on the ceiling is not just the rock/regolith above the tunnel that is pushing down, it's the rock/regolith which is able to transfer force to that. (See sketch below.) The angle (red lines) depends on the friction/cohesion of the rock/regolith. Same way rock anchors work, they aren't just pulling on the rock they are touching, but on the rock being pulled by that rock, etc, created an inverted cone. (In the case of lose material, it might be related to the angle-of-repose?)

We can pretty much assume that the habitat would be beneath loose soil and regolith, and it does in fact get really complicated. There are three four factors at play: diameter of the pipe, depth of the pipe and how stiff the pipe is plus the soil's properties which include things like Young's Modulus and also how wide the ditch is in relation to the pipe blah blah. Flexible pipes generally just take the load directly above them, as the previous examples have assumed but this would not be the case (flexible pipes are also counterintuitive because they are less compressed the deeper you go). Because the habitat is pressurised we must assume it is rigid. Therefore the soil transmits its load differently (soil actually forms internal arches). Rigid pipes in fact start taking up more load than the vertical column above them due to negative arching: the soil forms arches into the rigid pipe. Even at (especially at!) the relatively shallow depths we need for radiation shielding, this will create zones of pressure greater than the internal pressure and introduce bending moments to the pipe.

Then there's other stuff like bedding, because the weight of soil above must still be transmitted to the rock or soil below. Anyway, the pipe will bend a % or so when buried due to differential forces, so that has to be taken into consideration too.

There are ways and means to reduce these loads, especially with proper sidewall treatment, and a layer of compressible "geofoam" above the pipe.

(http://blog.achfoam.com/wp-content/uploads/2017/01/Arching-Effect.jpg)

Here's a visualisation of a soil arch:

(http://www-personal.umich.edu/~rlmich/public/images/arching1.jpg)

Here's a fairly simple solution from a nuclear war survival handbook (you gotta love Cold War optimism):

(https://www.oism.org/nwss/nw042.jpg)

By digging a simple ditch and laying some flexible (note the importance of that) pipes over the top, the soil forms a nice safe mound to protect you from nuclear blast and radiation.

Assumung you have time to dig it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/20/2019 05:30 am
Pretty much all of the NASA 3D Print Hab entrants proposed a dome with a flat base.

Many of the proposals in these kinds of NASA contests seem naive. But I'd disagree that "pretty much all" the proposals are pressurised domes.

On the naive side, the Team Zopherus one has the lander create a "pressured environment" for 3d printing (and an emergency shelter) simply by sitting, unanchored, on bare regolith. Eh, no. And sure enough, their design is a pressurised flat-bottomed dome. OTOH, the Hassell/EOC and SEArch+ seem to grok the issue. In both cases, their "domes" are unpressurised protective structures only. (XArch, otoh, talks about the "weight" of the 40t shell on the foundation (instead of several hundred tonnes of lift) and has no anchors, but at least they curve the bottom corners to enlarge the radius and reduce the forces, so perhaps their "dome" does work out as a flattened round rather than a true flat-bottomed dome.)

The focus on radiation by  SEArch+ was interesting. Especially with other teams adding roof skylights. It occurs to me that given how protected the inflatable modules were, which also gives thermal stability, I'm surprised they didn't have more transparent/translucent parts facing those light "collecting" shells. Add a pale or even reflective coating to the inside of these shells and a translucent skin on that side of the pressurised-hab and you'd drastically increase the amount of natural light entering the habs, while only slightly increasing the heat loss. (Which may actually be necessary, you do have to get rid of some heat.)

MARSHA is a skinny dome to cut down on the footprint when printing and to tower above the Martian landscape providing a good view.

Not just that, if you reduce the horizontal size, you reduce the ground anchoring required (although they still have some) both by reducing the cross-section and by increasing the weight over the base, although you increase the stress on the walls.

to cut down on the footprint when printing

I believe it's more about cutting down on overhang. 3d prints don't like printing over an opening. That shape is the best curve you can print without printing supports (that have to be removed.) The Hassell design uses an inflated, removable form to support the shell during construction. Not sure if SEArch+ checked their overhangs, didn't see any supports in the video presentation. Nor does X-Arch, but they seem to have checked, so maybe Mars gravity allows big overhangs?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/20/2019 02:10 pm
Pretty much all of the NASA 3D Print Hab entrants proposed a dome with a flat base.

Many of the proposals in these kinds of NASA contests seem naive. But I'd disagree that "pretty much all" the proposals are pressurised domes.

Quote
On the naive side, the Team Zopherus one has the lander create a "pressured environment" for 3d printing (and an emergency shelter) simply by sitting, unanchored, on bare regolith. Eh, no. And sure enough, their design is a pressurised flat-bottomed dome.

Team Zopherus seals the regolith before printing. All of the habitat designs had to have at least a 60% complete model with calculated pressure loads.

Quote
OTOH, the Hassell/EOC and SEArch+ seem to grok the issue. In both cases, their "domes" are unpressurised protective structures only. (XArch, otoh, talks about the "weight" of the 40t shell on the foundation (instead of several hundred tonnes of lift) and has no anchors, but at least they curve the bottom corners to enlarge the radius and reduce the forces, so perhaps their "dome" does work out as a flattened round rather than a true flat-bottomed dome.)

I noticed in X-Arc's concept image, they pile regolith around the base to make a slope. Soil pressure would counteract some of the forces in the base ring.

Quote
The focus on radiation by  SEArch+ was interesting. Especially with other teams adding roof skylights. It occurs to me that given how protected the inflatable modules were, which also gives thermal stability, I'm surprised they didn't have more transparent/translucent parts facing those light "collecting" shells. Add a pale or even reflective coating to the inside of these shells and a translucent skin on that side of the pressurised-hab and you'd drastically increase the amount of natural light entering the habs, while only slightly increasing the heat loss. (Which may actually be necessary, you do have to get rid of some heat.)



MARSHA is a skinny dome to cut down on the footprint when printing and to tower above the Martian landscape providing a good view.

Not just that, if you reduce the horizontal size, you reduce the ground anchoring required (although they still have some) both by reducing the cross-section and by increasing the weight over the base, although you increase the stress on the walls.

to cut down on the footprint when printing

I believe it's more about cutting down on overhang. 3d prints don't like printing over an opening. That shape is the best curve you can print without printing supports (that have to be removed.) The Hassell design uses an inflated, removable form to support the shell during construction. Not sure if SEArch+ checked their overhangs, didn't see any supports in the video presentation. Nor does X-Arch, but they seem to have checked, so maybe Mars gravity allows big overhangs?

SEArch+ is partnered with Apis Cor, which is a world leader in 3D printing of buildings. There is a big difference between the teams' ability to actually print stuff, which is a component of the competition.

The Mars ice house seems to be something that SEArch+ and NASA converged on independently. One of the big issues is the uncertainty over thick high-Z shielding with the nasty discovery of additional neutrons and pions/EM in materials simulations. The "design a Martian greenhouse" specifically says to design a habitat around a translucent-walled habitat, and they use images of the MIH.

(https://freight.cargocollective.com/w/1500/i/fdff347daa9c6b125d24a6c32955af45c81ec80a914042a31f93c9963ff7d830/LaRC-CAO_MIH_171023_d-CUTAWAY-SEC.jpg)

A trick which seems to have emerged is physical arrangement of the barriers. Instead of a simple padding like the 2017 dome, this 2019 dome has walls made up of ice blades. These apparently reduce the incoming radiation by 50% by using about 2/3 of the water a simple solid hemisphere would require, something which they validated with OLTARIS. I can only imagine this has something to do with some deflection of incoming particles as they hit the outer tips. Maybe this is applicable to larger domes too. Nope, no configuration voodoo, just putting ice where the radiation is mostest.

(https://freight.cargocollective.com/w/1500/i/aa3d1f4130d08e38a969a48ef0b9bdac44351a37d7136bec637f64129ac6a511/MIH_Plans_clean_2.jpg)

I saw this effect somewhere else too. A redesign of Orion's storm shelter (grab the boxes and hide behind them) showed that putting a water layer on the outside of the hull with no box piling in fact performed better than the grab-box-shelter with the water packs on the inside. Another paper showed that low Z outside of higher Z produced better results for the same mass. (6g/cm^2 Carbon outside 6g/cm^2 Aluminium seemed to be one of the best solutions)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/20/2019 09:09 pm
Team Zopherus seals the regolith before printing.

But no anchor (as far as I could tell from their presentation) to prevent the base of the lander from lifting (leaking) as soon as they try to pressurise it.

All of the habitat designs had to have at least a 60% complete model with calculated pressure loads.

That would be the pressure on the walls. Doesn't mean they model the "lift", unless they think of it. (Contrast X-Arch being concerned about the "weight" on the foundation. Whereas MARSHA uses anchors into the foundation to hold the walls (and hence roof) down.

The Mars ice house

Just putting in an "I told you so" regarding domes. Ice house (at least the NASA variant) is a rounded pressurised bladder under an unpressurised dome. Not a pressurised, flat-bottomed dome. Because pressurised domes are the wrong shape.

[Although I'm curious, is either CO2 layer partially pressurised? That would reduce sublimation. Or are they ambient?)

[edit: The "blade" result is interesting, too, not because of mass-reduction, but because it should reduce light-blocking compared to solid walls of the same thickness. That makes sunlight exposed agricultural spaces more viable, whether the wall is polymer-only, water-bladders or ice-bladders.]

Another paper showed that low Z outside of higher Z produced better results for the same mass. (6g/cm^2 Carbon outside 6g/cm^2 Aluminium seemed to be one of the best solutions)

(Just carbon or "carbon" meaning hydrogen rich polymer?)

That was something I'd been wondering, the best way to layer light/heavy elements. I knew that a heavy element outer layer (high-z) is worse than nothing for GCR because it produces a "shotgun" of high-energy secondaries, but are you better with light-then-heavy, heavy-then-light, light-only-but-thicker? Apparently it's light-then-heavy. Okay. But that heavy-then-light is worse than heavy-then-nothing (the Orion result) is very surprising.

But does that apply to Mars? In that the atmosphere serves as the high-z outer layer, making a low-z walled hab bad?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 02/20/2019 10:17 pm
Team Zopherus seals the regolith before printing.

But no anchor (as far as I could tell from their presentation) to prevent the base of the lander from lifting (leaking) as soon as they try to pressurise it.

All of the habitat designs had to have at least a 60% complete model with calculated pressure loads.

That would be the pressure on the walls. Doesn't mean they model the "lift", unless they think of it. (Contrast X-Arch being concerned about the "weight" on the foundation. Whereas MARSHA uses anchors into the foundation to hold the walls (and hence roof) down.

The Mars ice house

Just putting in an "I told you so" regarding domes. Ice house (at least the NASA variant) is a rounded pressurised bladder under an unpressurised dome. Not a pressurised, flat-bottomed dome. Because pressurised domes are the wrong shape.

[Although I'm curious, is either CO2 layer partially pressurised? That would reduce sublimation. Or are they ambient?)

[edit: The "blade" result is interesting, too, not because of mass-reduction, but because it should reduce light-blocking compared to solid walls of the same thickness. That makes sunlight exposed agricultural spaces more viable, whether the wall is polymer-only, water-bladders or ice-bladders.]

Another paper showed that low Z outside of higher Z produced better results for the same mass. (6g/cm^2 Carbon outside 6g/cm^2 Aluminium seemed to be one of the best solutions)

(Just carbon or "carbon" meaning hydrogen rich polymer?)

That was something I'd been wondering, the best way to layer light/heavy elements. I knew that a heavy element outer layer (high-z) is worse than nothing for GCR because it produces a "shotgun" of high-energy secondaries, but are you better with light-then-heavy, heavy-then-light, light-only-but-thicker? Apparently it's light-then-heavy. Okay. But that heavy-then-light is worse than heavy-then-nothing (the Orion result) is very surprising.

But does that apply to Mars? In that the atmosphere serves as the high-z outer layer, making a low-z walled hab bad?

On Mars at low elevations radiation would have to pass through a significant atmospheric barrier, but from directly overhead the atmospheric barrier is fairly thin. So it would make sense to have a non-uniform distribution of radiation protection in the habitat. Thicker directly above and then thinning to the sides.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/20/2019 11:51 pm
On Mars at low elevations radiation would have to pass through a significant atmospheric barrier, but from directly overhead the atmospheric barrier is fairly thin. So it would make sense to have a non-uniform distribution of radiation protection in the habitat. Thicker directly above and then thinning to the sides.

Looking at the refs quoted, 30 degrees to the horizon is your max safe window. Which is not much good for bringing in sunlight for agriculture, where 30-150 is your butter-zone. (Especially because the Martian atmospheric dust makes light-concentrators (like mirrors) much less effective, so you really do want line-of-sight to the sky.) If there's a "cheat" that lets you have direct (and indirect) sunlight, but low radiation for workers, that will be a huge bonus for ag areas. If it gives thermal stability on top of that, even better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/21/2019 09:29 am
If there's a "cheat" that lets you have direct (and indirect) sunlight, but low radiation for workers, that will be a huge bonus for ag areas. If it gives thermal stability on top of that, even better.

I wonder how effective this would be as a cheat, assuming visual spectrum reflectors are not effective at reflecting radiation: https://www.sciplus.com/3d-mirascope-illusion-toy-43878-p?gclid=EAIaIQobChMI5Yat1s3M4AIVipyzCh3LagyqEAQYBSABEgLdZ_D_BwE

You essentially get a skylight with all directions of light maintained, but the only radiation that can get through is straight down.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/23/2019 07:30 pm
Obviously, Musk Base won't be complete before it has received a Norman Foster-designed glass dome with a column of angled mirrors in the middle to throw light into the cavernous Elon auditorium below.

A bit like: http://www.magx.com/places/glass-dome-the-national-parliament-of-the-federal-republic-of-germany.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rondaz on 02/25/2019 06:50 pm
Elon Musk: The Popular Mechanics Interview

The SpaceX CEO on food, fuel, and the risk of vaporization.

As Told To Ryan D'Agostino Feb 25, 2019

https://www.popularmechanics.com/space/moon-mars/a26513651/elon-musk-interview-spacex-mars/?utm_source=reddit.com
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/25/2019 08:23 pm
That was the least interesting interview I've ever read of Elon Musk.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 02/25/2019 09:40 pm
That was the least interesting interview I've ever read of Elon Musk.

I don't disagree. But then there was one interview and Popular Mechanics produces a series of articles out of it. The first one was interesting, this one is not. Let's see if they have more interesting material.

Some people may interpret Elons remark on a moon base as an announcement that SpaceX will do it. I don't see it that way. It is just a wink. Anyone out there who wants a moon base? We can help you build one for a reasonable price.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 03/04/2019 05:01 am
So here is my latest idea for a Martian Habitat! I call it the Martian Temple. This is a radical departure from my previous ideas which relied far more heavily on brick, but since discovering the issues with the internal atmosphere, I've been hard pressure to make that idea stick.

It is essentially a steel silo 40 meters in diameter with a domed roof (either steel or steel/glass) with an 8mm wall thickness. Second floor is 10mm thick steel plate, reinforced with stringers.

The dome and second floor are supported on brick columns, with the side walls being welded onto a ground level steel sheet that is both the first floor and extended under the brick outer walls that offer both protection and anchoring (and it looks cool). Foundations are a 30 mm thick layer of Martian Sulphur-crete, using ~65 tonnes of Sulphur. All bricks used are Compressed Earth Bricks.

Construction is done via building the second floor and dome essentially at ground level then 'growing' the side walls using a rotating continuous welding system often used in gas and water tanks.
(http://cobratanks.com/images/cobra%20tank%20brochure.pdf)

Once construction of the outer shell is completed, air locks/connectors are cut and installed, then the Silo is pressurised, allowing for the second floor to be completed, and up to 4, 3 story brick and steel apartments being built in a shirts-and-sleeves environment, each housing up to 12 occupants in a spacious 30m2 for a total of 48 occupants.

The second floor has ~1200m2 of space and is rated to carry the equivalent of a layer of moist soil, 1 meter deep. This space can be used for anything from recreational parks, to gyms, to more buildings, to farming.

Total steel used is ~350,000 kg of low carbon mild steel, produced locally. Heat loss still needs more analysis, but is at least 450 kW radiatively, if the internal temperature is kept at 285K (10oC) with NO extra insulation.

Corrosion protection comes from sacrificial anodes of either aluminium or magnesium. Internal pressure is 50 kPa.

Reasoning:
 - Tanks like this are built very often on Earth
 - Domes and Cylinder offer the best volume-to-mass ratio
 - This process is highly automated, with the non-automated parts being very straight forwards.
 - Steel can readily be produced from the soil (which is on average 17% Fe2O3)
 - can be made to look cool

EDIT: Everything red/orange is steel, everything green is brick except the weird paternal on the ground which was for FEA. I left it in to show where the ground level is.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/04/2019 07:15 am
So here is my latest idea for a Martian Habitat! I call it the Martian Temple.

I think you're still not getting your head around the forces involved. A 40m diameter dome has an upward pressure of around 6 thousand tonnes (using your half-atm figure).

A 33mm layer of Marscrete is not going to hold that down.

Corrosion protection comes from sacrificial anodes of either aluminium or magnesium. Internal pressure is 50 kPa.

Again, you don't want to reduce the amount of buffer gas, unless you want a drastically increased fire risk.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Nilof on 03/04/2019 07:54 am
With martian gravity, 1 atm pressure lifts a ~30 m pillar of water. Or ~12 meters of concrete. If you want the pressure to be provided by stuff weighing down on it & compressive structures, you have to really bury yourself down deep.

If you want to have practical above-ground structures, you need tensile structures to handle pressurization, and you should not be inspired too much by Earth buildings.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 03/04/2019 10:53 am
So here is my latest idea for a Martian Habitat! I call it the Martian Temple.

I think you're still not getting your head around the forces involved. A 40m diameter dome has an upward pressure of around 6 thousand tonnes (using your half-atm figure).

A 33mm layer of Marscrete is not going to hold that down.

Corrosion protection comes from sacrificial anodes of either aluminium or magnesium. Internal pressure is 50 kPa.

Again, you don't want to reduce the amount of buffer gas, unless you want a drastically increased fire risk.

You'll pardon the bad joke if I say you've activated my trap card!

To be fair I should have explained a few things better.
The steel plating on the floor that the dome roof and tank side-walls weld into extends under the Brick outer facade which acts both as physical protection, radiation protection AND an anchoring force. I designed it to weigh more than enough to anchor the whole thing, espeacially since the Silo is fully enclosed. Additionally, the columns and mass inside will also act to anchor it.

The 30mm thick layer of Sulphur-crete foundations are under all of that (and another single layer of bricks) and are literally the foundations. Below that is compacted regolith but the Sulphur-crete is there to form a 'raft' to protect that structure agasint any settling after it is built.

Finally, the internal pressure comes from your advise over in the geodesic dome thread, though I'll admit I'm struggling to get my hands on the paper you quoted and am just using your advise for now. As for greater flammability due to reduced gravity, I don't have enough info so I'm ignoring that for now...worst case scenario I make the side-walls thicker. This design is very flexible in that respect and the stress analysis I've done for my load cases puts the peak stress well below even the fatigue limit of Steel let alone the Yeild stress.

50 kPa may be doable with higher oxygen content (somthing like 8psi, 32% Oxygen...or 8/32),
That would drastically increase your fire risk.
As for atmosphere, I'll check my source but my understanding was 8/32 had the right balance of increase percentage and decreased pressure to maintain a similar flammability.

Looking at what I have at hand, something which is on the just self-extinguishing at 14.7psi & 21% Oxygen will self-extinguish at 12/23 and 7/28. Therefore 8/32 is well over the line.

That's at 1g. At Mars gravity, flammability is even higher.

edit: clarity
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/04/2019 01:29 pm

You'll pardon the bad joke if I say you've activated my trap card!

To be fair I should have explained a few things better.
The steel plating on the floor that the dome roof and tank side-walls weld into extends under the Brick outer facade which acts both as physical protection, radiation protection AND an anchoring force. I designed it to weigh more than enough to anchor the whole thing, espeacially since the Silo is fully enclosed. Additionally, the columns and mass inside will also act to anchor it.

The 30mm thick layer of Sulphur-crete foundations are under all of that (and another single layer of bricks) and are literally the foundations. Below that is compacted regolith but the Sulphur-crete is there to form a 'raft' to protect that structure agasint any settling after it is built.

Finally, the internal pressure comes from your advise over in the geodesic dome thread, though I'll admit I'm struggling to get my hands on the paper you quoted and am just using your advise for now. As for greater flammability due to reduced gravity, I don't have enough info so I'm ignoring that for now...worst case scenario I make the side-walls thicker. This design is very flexible life that and the stress analysis I've done for my load cases puts the peak stress well below even the fatigue limit of Steel let alone the Yeild stress.

Are the pillars involved in transmitting pressure loads to the base plate?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 03/04/2019 07:24 pm

You'll pardon the bad joke if I say you've activated my trap card!

To be fair I should have explained a few things better.
The steel plating on the floor that the dome roof and tank side-walls weld into extends under the Brick outer facade which acts both as physical protection, radiation protection AND an anchoring force. I designed it to weigh more than enough to anchor the whole thing, espeacially since the Silo is fully enclosed. Additionally, the columns and mass inside will also act to anchor it.

The 30mm thick layer of Sulphur-crete foundations are under all of that (and another single layer of bricks) and are literally the foundations. Below that is compacted regolith but the Sulphur-crete is there to form a 'raft' to protect that structure agasint any settling after it is built.

Finally, the internal pressure comes from your advise over in the geodesic dome thread, though I'll admit I'm struggling to get my hands on the paper you quoted and am just using your advise for now. As for greater flammability due to reduced gravity, I don't have enough info so I'm ignoring that for now...worst case scenario I make the side-walls thicker. This design is very flexible life that and the stress analysis I've done for my load cases puts the peak stress well below even the fatigue limit of Steel let alone the Yeild stress.

Are the pillars involved in transmitting pressure loads to the base plate?

Yes, other wise the load of the second level is going entirely through the side walls and it doesn't like that.

Their spacing wasn't particularily optimised, but generally they form up 4, 5 meter wide streets the intersect in the middle.

Why 5 meters wide? Well generally as a standard so that large construction equipment can move through every Temple where needed. Again, better optimisation may allow for narrower streets and more living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/07/2019 08:26 am
I recently registered on OLTARIS, which is rather clunky and nasty but at least it's straightforward. I'm going to fiddle around and see if there are certain material combinations that cut down on radiation. The big problem is that getting more accurate data for Mars requires the use of a ray-by-ray model which seems to be very computationally expensive. I'm still trying to get basic material slabs to run but they're not queuing. Seems this is going to be a rather time-consuming exercise.

Anybody have any material combination (in terms of thicknesses) they want to try out?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 03/07/2019 10:21 pm
I recently registered on OLTARIS, which is rather clunky and nasty but at least it's straightforward. I'm going to fiddle around and see if there are certain material combinations that cut down on radiation. The big problem is that getting more accurate data for Mars requires the use of a ray-by-ray model which seems to be very computationally expensive. I'm still trying to get basic material slabs to run but they're not queuing. Seems this is going to be a rather time-consuming exercise.

Anybody have any material combination (in terms of thicknesses) they want to try out?

Oh wow! Thanks for the offer!
How hard was it to register on?

If you've got some free time, could you run 8mm Thick Mild Steel?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 03/08/2019 12:11 am
An idea for a quick and easy pressurised space.

Telescopic, cylindrical steel sections with flanges welded on each end, studs and seals already fitted.
Transported to site collapsed.  Put in location, extended, bolted together and pressurised.
could be a stand alone unit with an airlock on each end or join multiple units together at a central hub.

What thickness mild steel would be needed to hold say, 13psi ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/08/2019 01:18 am
An idea for a quick and easy pressurised space.
Telescopic, cylindrical steel sections with flanges welded on each end, studs and seals already fitted.
Transported to site collapsed.  Put in location, extended, bolted together and pressurised.
could be a stand alone unit with an airlock on each end or join multiple units together at a central hub.

How are you making the telescopy bits airtight?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/08/2019 01:27 am
An idea for a quick and easy pressurised space.

Telescopic, cylindrical steel sections with flanges welded on each end, studs and seals already fitted.
Transported to site collapsed.  Put in location, extended, bolted together and pressurised.
could be a stand alone unit with an airlock on each end or join multiple units together at a central hub.

What thickness mild steel would be needed to hold say, 13psi ?
Thickness is a function of diameter.  Are you thinking locally produced steel?  You will need rounded ends that might be complicated to transport in a single piece.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/08/2019 01:30 am
I recently registered on OLTARIS, which is rather clunky and nasty but at least it's straightforward. I'm going to fiddle around and see if there are certain material combinations that cut down on radiation. The big problem is that getting more accurate data for Mars requires the use of a ray-by-ray model which seems to be very computationally expensive. I'm still trying to get basic material slabs to run but they're not queuing. Seems this is going to be a rather time-consuming exercise.

Anybody have any material combination (in terms of thicknesses) they want to try out?
400 mm of compressed regolith would be nice.  I guess concrete would be similar. 5% water by mass?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/08/2019 02:14 am
I recently registered on OLTARIS, [...]
Anybody have any material combination (in terms of thicknesses) they want to try out?

10.8km scale height of mostly CO2, and the pattern of distribution of the radiation at the bottom. Angle vs intensity vs type.

10.8km scale height of mostly CO2 above the different secondary materials (polymers, steel, alum, water/ice, regolith) as top side (flat) vs 90 degree wall.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 03/08/2019 05:22 am
Outer cylinders have flanges on the ends facing inward while inner cylinders have flanges facing outwards.
When extended these flanges meet face to face with a seal between them and studs fitted to the outer flanges
so the nuts are fitted on the inside of the tube.

Internal pressure should force the joints together to assist with sealing.

For the ends I'm thinking prefab airlock units,  with all doors opening inwards, and fitted inside the flanges on the cylinder ends.

I'm thinking these would be initially sent from Earth as early days habs in the first few synods. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/08/2019 10:26 am
I recently registered on OLTARIS, which is rather clunky and nasty but at least it's straightforward. I'm going to fiddle around and see if there are certain material combinations that cut down on radiation. The big problem is that getting more accurate data for Mars requires the use of a ray-by-ray model which seems to be very computationally expensive. I'm still trying to get basic material slabs to run but they're not queuing. Seems this is going to be a rather time-consuming exercise.

Anybody have any material combination (in terms of thicknesses) they want to try out?
400 mm of compressed regolith would be nice.  I guess concrete would be similar. 5% water by mass?

The Martian regolith they have in the system is ~7% water by mass.
I recently registered on OLTARIS, [...]
Anybody have any material combination (in terms of thicknesses) they want to try out?

10.8km scale height of mostly CO2, and the pattern of distribution of the radiation at the bottom. Angle vs intensity vs type.

10.8km scale height of mostly CO2 above the different secondary materials (polymers, steel, alum, water/ice, regolith) as top side (flat) vs 90 degree wall.

They already have the Mars surface environment, in fact you can put in an altitude. It'll take me a while to figure out how to do stuff more complicated than slabs...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/13/2019 05:57 am
"Amazing" imo would be a huge city grid covering many km², even if the individual buildings themselves were of a practical and cost-optimized design. Does "amazing" automatically imply "expensive?" Everyone seems to agree that underground habitation is doable (and it provides a cost backstop), but could a sufficiently well-designed above ground hab be even cheaper? Or faster to build/deploy?

Here's my humble attempt at a first principles approach. Rather than start with a desired shape and work backward, I'll start with a mass-efficient pressure vessel and work forward. Something more than the standard tuna can.

Imo this approach is justified because pressure restraint is by far the largest structural load (including holding an n meter thick regolith shield overhead), and most ISRU-derived structural materials will be expensive and should still be conserved as much as reasonably possible. Mining and processing on Mars is costly, even if it's cheaper than Earth imports. Ultimately it's about minimizing total lifecycle cost per square/cubic meter per year — energy, water, labor, imports, etc. 

Lacking a better name I call it... The Waffle Hab. :) See attached image.

It's a straightforward cellular pressure vessel with the cells aligned with individual rooms and levels. Cellular hab designs must have some optimal cell size, and this seems like a natural choice. Preferred initial implementation is inflatable so it can be acceptance tested on Earth, stowed in a small volume, and quickly deployed. This provides bulk volume for early missions without tying up too many personnel on construction tasks, or alternately it maximizes the output of a given size construction crew. Gradually it would transition to ISRU materials and manufacturing as changing costs dictate.

Advantages

It's a thin-walled pressure vessel having the same geometric efficiency as a cylindrical cross-section, but it creates vastly more human-accessible space (ie not just a big open void). Thin-walled vessels are pure tensile structures so they have high mass efficiency, such that even rigid habs should assume shapes like inflatables to minimize mass — think of the inflatable as a physical "form-finding" model for discovering purely tensile geometries.

A 40 meter long hab with this cross-section would provide 3000 m² of floor space, and if using Kevlar its pressure restraint would mass only 6.7 tonnes, or 9.4 tonnes for basalt fiber (assuming 4x safety factor and 100 kPa pressure). It needs an air bladder and anti-scuff layers too of course. Transhab used a CombiTherm liner for low permeability, but aluminum oxide sputtered films are thinner and have even lower measured leak rates (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080010625.pdf). Anti-scuff layer might be Nomex like Transhab, or non-structural glass fiber (since many sources of ISRU glass will likely contain high iron content).

The floor is held in high tension and supported at each internal wall, so even a non-rigid design would have very little sag. A rigidizing secondary floor structure could be added if necessary, but at the cost of increased mass, stowed volume, and deployment complexity. Hopefully this is not needed for most structures.

No heavy-duty rock anchors. The "basement" cavities would be insulated to minimize conductive heat loss and avoid destabilizing the permafrost (more an issue in dense city grids than for standalone buildings).

Water or regolith can go on top for radiation protection, and if necessary in the outer wall cavities. No buoyancy problems. A regolith shield might use waste from tunneling or water mining. A water shield could allow plants to grow under natural light in the "attic" space, or that volume might be used as a gravity-fed water tower and rad shield. It can also provide inexpensive volume for fully-artificial illumination, with tensile supported hydroponics, flexible tank bioreactors, and suspended lights and ductwork for an ultralight and quick-to-setup growing volume. Many possible layouts here, so the design is intentionally "unopinionated" on other decisions such as fully artificial vs some natural light, regolith vs water shield, material selection, and even inflatable vs rigid (both have advantages, but imo inflatable will have a lower overall cost for at least the early missions, and probably long after).

Equipment and furnishings can have lightweight tensile secondary structures and be mounted to load rated break-safe loops in the ceiling, walls, and floor. These include internal fabric partitions, equipment racks, lights/electrical/plumbing, stowage sacks, lay-flat hammocks (~1kg for a bed/chair), and cable-supported NFT hydroponics ala UA's M/LGH. Some interior components might be pre-installed on Earth, saving labor on early missions. Operational constraints should be in place to avoid overloading and excessive floor deflection for non-rigid designs.

I'm sure I'm missing a lot, but a few of the more obvious problems/challenges include:

Walking on a fabric pressure vessel under tension? Yikes! But I think it can be made ok if covered with a suitable load-spreading foam "carpet underlayment" and an appropriate thin hard-wearing traction floor — picture a souped-up vinyl carpet protector, though perhaps not actual vinyl. Or instead of foam, perhaps alternating-direction layers of coroplast (or per the low-tech survival thread, cardboard) to spread out point loads.  Whatever the floor protection layer[​s] ends up looking like, it's almost certainly lighter/cheaper/less work than building a complete standalone structural floor and supporting wall/column structures (which is effectively what is replaced).

It still needs a lightweight structure to support the radiation shield and floors if pressure is lost. This feature reduces loss of equipment, but not necessarily loss of life. One possible design has internally-supported roof trusses, another resembles a suspension bridge with external towers. IMO long-term this won't actually be necessary once high pressure reliability is demonstrated (similar to Starship omitting the "necessary" LES), but it's needed for early buildings.

There are complex seams at the intersections. Probably early designs will be conventional sewn seams doubled with reinforcing straps. One possible solution is multi-way buckles, which might allow individual segments to be replaced without sewing (partly mitigating the floor wear risk). Heat welded bladders (similar to Transhab) could re-seal compartments to meet leaktightness and redundancy requirements specific to each structure.

Expansion and contraction with temperature and pressure can cause structural fatigue and abrasion. In extreme cases the entire structure could "walk" with each cycle. I assume that suitable materials, structural margins, anti-scuff layers, guy wires, thermal/pressure regulation systems, and maintenance schedules can solve this.

Vibration and cyclic loading due to people walking and equipment operating is much smaller amplitude than pressure cycling, but higher frequency. Watch for resonance and fatigue limits. Structural margins and de-tuning/damping the building's resonance at walking frequencies should fix this, but in the worst case steel or titanium can be used for high cycle load parts.

To move between sealed compartments I envision pre-fab frames that attach to the wall straps, with a pressure-sealing door. Each side is an I-beam to transmit load around the opening. Smaller hatches allow maintenance access.

How to wire/plumb between pressure-isolated compartments? My idea is to route these between the weave of the pressure restraining straps (making a hole in the air bladder lamination layer), with a sealing plate over the opening from both sides. Internal partitions are contingency air bladders only, so acceptable leak rates may be relatively high.

Any pure tensile wall/ceiling/floor will shift in response to pressure changes in adjacent compartments. This could pose a problem for material strain rates, causing secondary liner damage, or directly causing injury to occupants. Still better than instant depressurization, and again I think the ultimate solution is "don't depressurize the adjacent compartment," but additional work is needed to mitigate this risk. The obvious solution is to replace the pure tensile webbing with foam-core composite panels with enough profile thickness to resist the bending moment, but this carries a significant design penalty.

Sound transmission between rooms could diminish privacy. I assume additional acoustic layers would be used for private areas if needed (suites, bedrooms, private offices, etc). Also equipment and ventilation will provide noise.

Variations

Naturally this design can be imported from Earth and/or made on Mars. Possible tensile materials include carbon fiber, kevlar, basalt fiber, glass fiber, steel, or UHMWPE.

The same geometry can be made self-supporting rigid structure by rotating the "waffle" to a top-down view. The outer hoops are rigidized like grain silos, and the inner rooms have diagonal bracing.

If large open spaces are needed, the tensile walls can be replaced with a grid of I-beams or cables, with flat trusses at the outer walls to spread load between spans. Using I-beam verticals can yield a self-supporting regolith shielded design.

Anyway this post is already much longer than intended, so I'll leave further discussion of thermal, airlocks, deployment, operation, design evolution, and optimizations for another post. So please kindly rip this design to shreds let me know what I've overlooked. ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/13/2019 01:57 pm
Impressively thorough presentation, kudos!
Title: Re: Envisioning Amazing Martian Habitats
Post by: KSHavre on 03/13/2019 11:12 pm
Is it me, or are there quite a few interesting or in-depth posts from members with less than 10 posts, lately? This idea is very simple and an effective use of space, but the head-height clearance on each floor jumped out at me. Having to remain in very tight quarters indefinitely may be too claustrophobic for many. If you could try the same idea with only 3 'people' layers, it might seem more psychologically sustainable?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/14/2019 09:08 am
Posting on phone so I must be brief. As you say, essentially you are inflating square boxes, if one cell deflates the surrounding walls will bulge and crush fixtures/people unless they have full-pressure restraint. Point loads such as furniture and fixtures will strain the downward-bulging cells. The overall "box" waffle will also bulge to an oval shape even with restraints unless they are rigid, like metal beams. This means different strapping strengths for each outer cell bulge. Overall loading also has to converge on a single point to work, ie a pumpkin stem. Also, if cells are pressure isolatable that means rigid pressure doors between them.

The simple alternative is imported ISRU or imported steel sheeting welded to make airtight structures, so not seeing a great advantage to this difficult inflatable shape so far.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/14/2019 09:30 am
Thanks Oersted and KSHavre for your kind words. Long time poster, first time lurker! Er scratch that... reverse it.

Specific parameters like dimensions, number of levels, and width of rooms can and should be tweaked (and might vary between buildings). I needed to choose something for the illustration though.

Regarding "very tight quarters," I chose a height of 2.5 meters (8' 2.4") specifically because standing in a room with an 8 foot high ceiling felt more than comfortable/spacious, although I'm 5' 11" (180 cm) and the human figures are somewhat arbitrarily 6' 4" (193 cm), ie the NASA height limit for mission specialists. I'd be cautious estimating occupant claustrophobia by viewing it as a dollhouse on a screen. There's simply no substitute for standing in a space and feeling it, which is what makes VR so compelling.

Also this particular dollhouse would look less claustrophobic if it weren't crammed with people to show the floorspace. :)

Higher ceilings naturally come at the cost of proportionally more mass, so the question is, "how much is enough?" Architects Christopher Alexander et al recommend 10-12' (3.0-3.6 meter) ceilings for public spaces (Ceiling Height Variety, pattern #190 in A Pattern Language (1977)). They summarize:

Quote
Therefore, vary the ceiling heights continuously throughout the building, especially between rooms which open into each other, so that the relative intimacy of different spaces can be felt. In particular, make ceilings high in rooms which are public or meant for large gatherings (10 to 12 feet, 3.0 to 3.6 meters), lower in rooms for smaller gatherings (7 to 9 feet, 2.1 to 2.7 meters), and very low in rooms or alcoves for one or two people (6 to 7 feet, 1.8 to 2.1 meters).

This suggests 2.5 m or similar should work for private dwellings and apartments, economizing the mass of the pressure restraint, wall air bladders, wall protective layers, and the air itself, which surprisingly is more massive than the restraint layer. All these masses scale in proportion with ceiling height, and the costs will scale close behind.

For example a Mars hotel might have its first-floor lobby and conference rooms 3.5 m high, above which are multiple 2.5 m floors for regular rooms, and a 3.0 m penthouse level. An open multi-story arcade or two might be built by replacing certain floor segments with criss-crossed cables and peripheral I-beams.

The decision to use four floors comes from the near universal limit in old-world urban architecture observed by Alexander et al (Four Story Limit, pattern #21), so rather than preserve whatever the building height is I'd keep the same number of floors and make the building taller. Clearly there's some cost-optimal number of floors (related to thermal or rad shield scaling? other human factors?), but I haven't the foggiest idea what that is yet. :-\ Suggestions are most welcome.

Lampyridae, thanks! I'm composing a reply for you now.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/14/2019 10:10 am
From what I understand, you are basically making a collection of cells, so the final building will look something like this, with more regular, puffy cell elements (think chocolate slab-sided boxes).

(https://upload.wikimedia.org/wikipedia/commons/5/5a/Beijing_National_Aquatics_Centre_1.jpg)

There's really no need to worry about internally pressurisable rooms. If something has punched through to the middle room to make a leak, you have bigger things to worry about. Buildings are very large and will take time to depressurise - rather have designated safe havens designed in. So the internal layout can be much simplified.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/14/2019 10:25 am
Posting on phone so I must be brief. Essentially you are inflating square boxes, if one cell deflates the surrounding walls will bulge and crush fixtures/people unless they have full-pressure restraint.

I talk about this the paragraph starting "any pure tensile wall/ceiling/floor will shift in response to pressure changes in adjacent compartments." I'm not too worried about crushing since they're either A) still at partial pressure so the walls won't deform enough, or B) fully depressurized, therefore anyone is unconscious in 10 seconds and dead in 90.

As I said, the ultimate solution is "don't deflate the cells." High reliability solves a lot of problems.

Point loads such as furniture and fixtures will strain the downward-bulging cells.

Any deflection is incredibly tiny. This is why I specified "load rated break-safe loops in the ceiling, walls, and floor" (as in, each individual loop has an individual load rating) and that "operational constraints should be in place to avoid overloading and excessive floor deflection for non-rigid designs."

The rectangular waffle will also bulge to an oval shape even with restraints unless they are rigid, like metal beams.

It sure looks like they would, doesn't it? But if the pressure is the same across both sides of the restraint, it will be completely flat and in pure tension. Just look at the inner wall between conjoined soap bubbles of the same diameter.

The outer surfaces (the ones holding differential pressure) are indeed all curved, as expected. No magic here, just force diagrams!

This means different strapping strengths for each outer cell bulge.

The outer hoops are effectively sections of cylindrical pressure vessels, so they need twice the strength in the hoop direction as in the axial direction. But otherwise each outer hoop of the same size has an essentially identical restraint layer.


Overall loading also has to converge on a single point to work, ie a pumpkin stem.

It's one option, but what makes you say it's the only workable geometry? I see no basis for that claim.


Also, if cells are pressure isolatable that means rigid pressure doors between them.

Indeed, I mentioned that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/14/2019 11:14 am


The same geometry can be made self-supporting rigid structure by rotating the "waffle" to a top-down view. The outer hoops are rigidized like grain silos, and the inner rooms have diagonal bracing.

If large open spaces are needed, the tensile walls can be replaced with a grid of I-beams or cables, with flat trusses at the outer walls to spread load between spans. Using I-beam verticals can yield a self-supporting regolith shielded design.

Anyway this post is already much longer than intended, so I'll leave further discussion of thermal, airlocks, deployment, operation, design evolution, and optimizations for another post. So please kindly rip this design to shreds let me know what I've overlooked. ;)
I think your illustration shows it very well, but actually illustrates the opposite conclusion.   If you build a conventional building inside a circular thin walled pressure vessel it will always be less expensive than a building built from a number of reinforced pressure vessel walls.  Because the interior building is a simple conventional gravity structure, while the reinforced fabric building is a tension structure, requiring much higher quality materials and al large number of complicated joints and fittings.
So you need to complete the circular illustration with conventional floors and then compare costs, noise control and such.  I think the conventional building will win.  Could be wrong though  :-)  worth a spreadsheet, I expect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/14/2019 10:41 pm
Thanks, great points! I'll try to cover them.

From what I understand, you are basically making a collection of cells, so the final building will look something like this, with more regular, puffy cell elements (think chocolate slab-sided boxes).

(https://upload.wikimedia.org/wikipedia/commons/5/5a/Beijing_National_Aquatics_Centre_1.jpg)

What I described has the sides and top covered in rows of hoop sections, but you present another promising wall geometry.

Should the "pillows" be aligned to a square grid, hex grid, or triangle grid? Ignore internal layout considerations for a moment, what's the relative mass efficiency?

Briefly here's my ontology of cellular hab geometries. A pure tensile cellular outer wall can be restrained into a "button" geometry (a grid of point tensile restraints), "hoop" geometry (rows of linear restraints in one direction, either webbed tensile partitions or beams/trusses or cable stay), a "quilted" geometry (rows of linear restraints in multiple directions), or some hybrid approach (perhaps discontinuous linear restraints like a dotted line). The grid can be square, rectangular, hex, or triangular, and the size can vary.  And all these parameters can change with axis. For instance a hab might have horizontal "hoop" geometry at the sides and a hexagonal "quilted" geometry at the top and bottom; that would look pretty cool imo.

There's no shortage of design options to explore. Many should work, so Cellular City needn't be visually boring either inside or out.

There's really no need to worry about internally pressurisable rooms. If something has punched through to the middle room to make a leak, you have bigger things to worry about. Buildings are very large and will take time to depressurise - rather have designated safe havens designed in. So the internal layout can be much simplified.

Agreed, thank you for stating it so clearly. I was trying to convey that to the extent that individual building/room requirements dictate pressure-isolated compartments, they are easy and inexpensive to provide with this design. If isolated compartments are not needed then the air bladders, utility penetration seals, and rigid pressure doors (but not the rigid door frames) can be deleted from those internal partitions. Only the "designated safe havens" need those features, and the space around them can have sufficient equipment clearance to accommodate partition deflection.

the interior building is a simple conventional gravity structure, while the reinforced fabric building is a tension structure, requiring much higher quality materials


Except that's apples to oranges. It ignores the cylindrical pressure restraint itself, which requires the same amount of high quality tensile materials. So once you build the waffle pressure vessel, you get the gravity structure almost "for free" (as I pointed out will require more mass for seams and protective layers, see below).

Also, I'd look again at the materials and construction used in the nearest "simple" gravity structure, eg a big box store. Large cost-optimized buildings use steel deck truss composite floor/roof systems (I realize that Mars costs are not necessarily analogous, but this provides a starting point that's at least not egregiously boneheaded structurally). If the bottom chord of a deck truss fails it's not good either (modulo structural redundancy and safety margins, same as any good hab design), so I'd question your premise that lower quality materials are required for gravity structures vs tensile structures.

Maybe you're picturing a different type of floor?

As Buckminster Fuller observed, tensile structures are good for weight optimization — a crane's cable weighs much less than its tower truss. Since I'm starting with a fully-loaded pure tensile structure it automatically has the highest theoretical volume to weight ratio (modulo the outer cylindrical surface's non-sphericality, which causes a surprisingly small penalty). A tensile design is automatically mass optimized. So even if you're building with Mars steel, you still want to prefer tensile structures to reduce steel mass.

and a large number of complicated joints and fittings.

Exactly. Those are the real design penalties here (not the tensile material whose cost are almost entirely offset by "deleting" the cylinder). But even those penalties aren't so bad.

Sewn doubling straps aren't terribly heavy or complicated. Transhab and Bigelow have proved out the basic assembly steps, and this would be a further development of that technology. One open question is, what's the minimum feasible mass for a "hot swappable" buckle system? This would allow not just replacement of worn partitions, but reconfiguring/expanding existing buildings, and more easily reusing spare parts from decommissioned buildings.

Sealed rigid pressure doors are needed for any hab design requiring redundant isolated compartments, so if you need redundancy you're already paying the door and frame mass penalty. And the sealed wiring/plumbing penetration fittings I mentioned would be very lightweight (due to the very small "span" covered, only 1-2 inches or 2-4 cm) and aren't a significant mass or cost.

The big mass penalty is the floor and wall protection layers. And as I said it should mass less, cost less, and require less work than the full standalone floor and supporting structural walls/columns which it replaces. I still think this pro-cellular thesis is fundamentally correct.

Again I like the idea of a self-supporting design using vertical I-beams and trusses, but I think you design the I-beams to double as vertical tension elements, and the load-spreading trusses to double as contingency roof / rad shield support. Avoids "box within a box."

Floor trusses (or other thick floors) have another hidden cost because they consume expensive and valuable pressurized volume. Pressure vessel scaling doesn't care whether you made fully useful office space or less useful truss volume. The obvious counterargument is that you can still run utilities there, so it's not totally wasted volume. Problem is the volume isn't quite as useful but only fractionally so, since I doubt "tucked away space for utility runs" will be the limiting constraint and not truss thickness. Appropriately sized cable/plumbing raceways along each wall and film ducts in the awkward high corners, along with an equipment room or two, and that should suffice for servicing most apartment or office environments. Making space for cable runs therefore offers very thin justification for intentionally creating truss space you wouldn't otherwise. This implies that very thin floors have a cost advantage simply due to the side effect of reducing total pressure vessel volume/mass.

Really what I'm attempting is a breadth-first search through the entire Mars hab design space, so given the scope there's necessarily a lot of Fermi estimation for early "branch prediction" of major design decisions, but nevertheless my goal is for all the numbers to close in detail. This is an infant design that's still very fluid, which I hope explains my many caveats and back-and-forth waffling (ha).

And for my next trick, I shall persuade you all that what my thin-walled pressure vessel really needs is... corners! ??? :D Stay tuned.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/15/2019 06:59 am
Quibble:

Regarding "very tight quarters," I chose a height of 2.5 meters (8' 2.4") specifically because standing in a room with an 8 foot high ceiling felt more than comfortable/spacious

Eight foot (or 8'4") floor-to-floor height does not create "8 foot high ceilings".

Floor separation must take into consideration the thickness of the floor, any under-floor/false-floor structure (such as drainage), any false-ceiling/drop-ceiling space for ventilation and utilities. (I don't know the regs, but from what I've seen, it's unusual for commercial facilities to have false-ceiling space less than a third of the usable floor-to-ceiling height.)

(I also agree with Lampyridae about purely tensile floors. You need a compressive structure over the tensile one in order to smooth out the point-loads from actual use. The difference between a hammer and a nail.)



Less quibbly, more curious...

Previously in this thread (I can't find it now, but I think it involved KelvinZero, lamontagne, and myself), we discussed cellular structures, but with a focus on them being modular, expandable.

Do you think you can change your structure such that the cells can be added, changed, after an initial structure is built?

(The obvious way is to move the primary strength from the walls to a frame that runs through the joins/intersections of your illustration, with the walls only existing to transfer air-pressure force to the frame. But that is so different from your assumptions, I'm not sure if it remains yours.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/15/2019 07:03 am
"waffle"
I think your illustration shows it very well, but actually illustrates the opposite conclusion.   If you build a conventional building inside a circular thin walled pressure vessel it will always be less expensive than a building built from a number of reinforced pressure vessel walls.  Because the interior building is a simple conventional gravity structure, while the reinforced fabric building is a tension structure, requiring much higher quality materials and al large number of complicated joints and fittings.

I believe the argument is to move some of the required external structural mass inside the overall building, and then use that to also live on/in/through. In other words, the mass of the interior structure replaces mass that would otherwise be part of the exterior. Same overall mass as an empty single volume. In effect eliminating the entirety of the interior (compressive) building.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/15/2019 10:24 am
Ahhh, hoop sections. That makes a lot more sense to me. I thought you were describing a stack of cylinders, ie a hot dog packet. Stacked hoops makes more sense. Stacked square hoops are going to be interesting. Your proposal is most similar to the hexagonal inflatable station NASA was thinking about in the 60s.

Box-shaped pressurised structures are doable but they're a pain. This is one of those Amazon packaging pillows you get. Internal pressure is typically around 0.2 atm.

(https://p.globalsources.com/IMAGES/PDT/BIG/047/B1159405047.jpg)

Note that the pinching-in of the long sides is the greatest due to the strain from internal pressure in the centre being the greatest, so what you want will be a cube. Of course, you could deliberately use this to your advantage: make the low-tension corners where you have your weaker transparent material. I assume this is what you're advocating with the angled corners?

Adding cells, making it more spherical (ie a cube) gets rid of this tendency to bulge, like those inflatable ottomans.

However, in terms of radiation shielding, you have to generate more ISRU mass for the same quantity of shielding. Domes are the optimal shape for a shielded volume, also in part because they are self-supporting and easy enough to build. You will need at least 2 metres of material to achieve anything like an acceptable radiation reduction. And the more mass you have inside your habitat, pot plants, furniture etc the more shielding you get on top of that. So there is a bonus to having traditional concrete/brick internal structures.



Regarding using fabric for flooring... I don't think it's worth the mass savings. For reasons Paul451 mentioned, but also because fabric stretches and wears over time. Human footsteps in Mars gravity actually generate 2/3 of the forces they do on Earth (on the Moon, just under 1/2), so the loads are not that reduced. And if a tensioned fabric starts ripping, it can keep on ripping, dumping the room's contents into the room below. There are a lot more reasons I don't think it's a fantastic idea in the context of a permanent habitat, those were the two main ones. Bear in mind, I don't deal with tensile fabric structures at all in my day job (just accounting for stretch and slippage in steel cable), I just know from what I've picked up that inflatables and fabrics are kind of a specialised art, and do come with their own issues which must be managed.

I don't think rigid material for internals will be a problem. NASA already has a machine that chomps the crew's garbage and turns it into plastic. The bonus of thick floors is that they double as shielding for the people below you. And there is plenty of regolith to sinter or glass or otherwise turn into bricks with very little production effort.

However, using fabric partitions for early settlements would be a good idea. Rounded interiors give an impression of greater space, so you could use tensile fabric structures to make a very stylish and zen interior. You could also have simple fabric wall partitions on an aluminium frame. Tensile fabric would also be a good debris protection from Starship landings, fairly easy to stretch over delicate modules into a kind of ballistic tent.

(https://www.kasubaworks.com/uploads/9/5/3/0/95300938/3-ivein-3_orig.jpg)

As for multi-cell designs, are you familiar with noded spheroid tank geometries (below)? They're used for partially-pressurised tanks, although they've fallen out of favour due to difficulty inspecting the nodes between the toroid sections.

As for cellular structures, the Beijing Water Park is basically an empty box with fancy walls. Interconnected cells without a rigid framework would strain unevenly with the centre roof and floor of the box getting the most strain, and the outer cell corners more relaxed.

For the inflata-cube design, simply having cubic subdivisions on the inside makes the most sense. Other primitives don't lend themselves well to human-occupied rooms, no matter what architects would have us believe :P . The strapping of the exterior surface would have to be given some careful thought... the straps clustering around the centre since that's where there is the most strain. Probably have aluminium truss edges. Something like this, but each cube face is like 3m on a side. Internal tension control would come from steel cables because of their tendency to not elastically stretch or degrade.

(https://www.dhresource.com/0x0s/f2-albu-g7-M00-C8-09-rBVaSlrNWDqALh2RAAE4M1fVQag583.jpg/inflatable-cube-tent-customized-large-white.jpg)

The exterior mass required for insulation and protection from the Martian environment (abrasion, UV etc) would be approximately 1.4x that of a sphere of identical volume (sqrt 6: sqrt pi). Actually, a shade more than that since the cube faces are pillowing.



Going back to radiation shielding materials, OLTARIS tells me that a 2m thick dome (well, sphere) on Mars reduces the radiation dosage inside to about 1/4 of the unshielded surface dose. So that's 20g/cm^2 of CO2, 200g/cm^2 of H2O and the surface blocking half the incident GCR is 300cm of regolith (this is modeled for backscatter).

Next I'll try with 200g/cm^2 of Martian regolith and then try a mix of 100g/cm^2 ice then 100g/cm^2 regolith to see what that does.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 03/15/2019 12:39 pm
Regarding "very tight quarters," I chose a height of 2.5 meters (8' 2.4") specifically because standing in a room with an 8 foot high ceiling felt more than comfortable/spacious, although I'm 5' 11" (180 cm) and the human figures are somewhat arbitrarily 6' 4" (193 cm), ie the NASA height limit for mission specialists. I'd be cautious estimating occupant claustrophobia by viewing it as a dollhouse on a screen. There's simply no substitute for standing in a space and feeling it, which is what makes VR so compelling.

Don't forget that the gravity on Mars is only 0.38 g. Walking will be a slow and cautious affair if you don't want to hit the ceiling. Also some major health problems in micro (or reduced) gravity are caused by not enough muscle and bone loads, which means that you actually want to encourage people to jump, climb, run and generally strain their bones and muscles during normal day to day activities.

Having more vertically oriented habitats forcing the inhabitants to put effort into moving around could be quite imperative if you don't want to force them to strap themselves for two hours a day onto exercise machines.

This is a sharp contrast to weightlessness, where you have no choice. But if you have a third of a g, you can work with this. Orientation doesn't matter in zero g, in full gravity horizontal orientation is more convenient, but in reduced gravity vertical orientation might be just better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/16/2019 09:10 am
Sorry for the long post, but I want to clear up any misconceptions.

Eight foot (or 8'4") floor-to-floor height does not create "8 foot high ceilings".

By "height" I meant floor to ceiling height.

Floor separation must take into consideration the thickness of the floor, any under-floor/false-floor structure (such as drainage), any false-ceiling/drop-ceiling space for ventilation and utilities. (I don't know the regs, but from what I've seen, it's unusual for commercial facilities to have false-ceiling space less than a third of the usable floor-to-ceiling height.)

Again my understanding is that it's driven by the minimum profile thickness of the floor truss, not the pressing need for utility space.

Sure, if you're stuck with all this otherwise-useless truss space it makes sense to put utilities there. But my supposition (partly based on observing the low volumetric density and poor packaging efficiency of utilities in such false ceiling spaces) is that clever packaging can redistribute these utilities in a less volumetrically wasteful way, in part by utilizing otherwise awkward or dead spaces.

I assume that both the high cost of pressurized volume and duct mass will drive toward high velocity ducts, which reduce duct volume by 75% at the expense of blower power. There's of course some "best" (cost-optimizing) duct speed that balances these two factors, but with pressurized volume at such a premium I think the design trades will settle on a higher duct speed/pressure than found in commercial buildings on Earth (which, naturally, have no incentive to conserve their "free" truss space).

Note also that the outer wall/attic/basement hoop space provides a convenient volume for running specialized oversized utilities the length of the hab (I suppose one limitation is that "only" 14 out of 20 compartments are adjacent to a hoop space). If not used as a redundant double-layer wall, the entire hoop volume could conceivably be used as large supply and/or return ducts. Not sure if this makes sense, but it's an option.

Regarding using fabric for flooring... I don't think it's worth the mass savings. For reasons Paul451 mentioned, but also because fabric stretches and wears over time. Human footsteps in Mars gravity actually generate 2/3 of the forces they do on Earth (on the Moon, just under 1/2), so the loads are not that reduced.

But is it worth the mass/material savings + pressurized volume savings + Martian assembly labor savings?

Unfolding a hab, anchoring it, and inflating it is much easier than bolting together a rigid structure from pre-fab parts (especially wearing a pressure suit).


(I also agree with Lampyridae about purely tensile floors. You need a compressive structure over the tensile one in order to smooth out the point-loads from actual use. The difference between a hammer and a nail.)

I also agree with Lampyridae and Paul451! After all, I wrote:

Walking on a fabric pressure vessel under tension? Yikes! But I think it can be made ok if covered with a suitable load-spreading foam "carpet underlayment" and an appropriate thin hard-wearing traction floor — picture a souped-up vinyl carpet protector, though perhaps not actual vinyl. Or instead of foam, perhaps alternating-direction layers of coroplast (or per the low-tech survival thread, cardboard) to spread out point loads.  Whatever the floor protection layer[​s] ends up looking like, it's almost certainly lighter/cheaper/less work than building a complete standalone structural floor and supporting wall/column structures (which is effectively what is replaced).

Beyond just raising the problem again, is something unworkable about my solution? Because it seems to at least plausibly address the issue (I'm not suggesting it is solved of course, just that it appears solvable within a reasonable mass and R&D budget).

And if a tensioned fabric starts ripping, it can keep on ripping, dumping the room's contents into the room below.

Practically all structures can be subject to cascading failure, and the solution is the same: redundancy, structural margins, and inspection and maintenance.

Do you think you can change your structure such that the cells can be added, changed, after an initial structure is built?

I have proposed loops threaded into multi-way buckles (or more technically, clews) that open to free/capture the loop.
During replacement the wall would first be detensioned by installing special temporary perimeter beams. These attach to each clew and have cables spanning between them, and this assembly assumes the tension during replacement. No heavy equipment needed.

The simplest clew is just four rods (for the straps to loop around) all bolted together by two rounded squares on each end, with a hole in the square where the pins for the temporary support beam engage. I'll have to draw a picture.

(The obvious way is to move the primary strength from the walls to a frame that runs through the joins/intersections of your illustration, with the walls only existing to transfer air-pressure force to the frame. But that is so different from your assumptions, I'm not sure if it remains yours.)

Not different at all! In fact I mentioned that configuration as one possibility, and I think it's a good one.

Nothing's set in stone yet, but I worry the diagram mistakenly gives people that impression. I drew it mostly to illustrate my geometric/engineering argument in favor of cellular hab designs. Don't mistake it for The Final Design (or even the current design-in-progress).

Ahhh, hoop sections. That makes a lot more sense to me. I thought you were describing a stack of cylinders, ie a hot dog packet. Stacked hoops makes more sense. Stacked square hoops are going to be interesting. Your proposal is most similar to the hexagonal inflatable station NASA was thinking about in the 60s.

Thanks, I didn't know about that!

Box-shaped pressurised structures are doable but they're a pain. This is one of those Amazon packaging pillows you get. Internal pressure is typically around 0.2 atm.

(https://p.globalsources.com/IMAGES/PDT/BIG/047/B1159405047.jpg)

Note that the pinching-in of the long sides is the greatest due to the strain from internal pressure in the centre being the greatest, so what you want will be a cube.

Squares do minimize strain anisotropy, but they also add assembly complexity. I think you just terminate the hoops in a pillow shape like this (which is fine, because as you point out it experiences less stress than a cylinder).

My goal is "nothing left to take away." Why perform assembly in two directions when you could just double the thickness of the straps in the hoop direction and eliminate half the seams?


Also, wouldn't a quilted hexagon grid be closer to the ideal spherical section? I'm not suggesting hexagonal rooms (which have obvious problems), but a hexagonal grid of vertical posts. This appears almost identical to a square grid except each row is staggered.

Of course, you could deliberately use this to your advantage: make the low-tension corners where you have your weaker transparent material. I assume this is what you're advocating with the angled corners?

Close, but that's not quite it. :) I want to respond to everyone's questions and comments first.

It's perfectly fine to put the weak transparent material across the entire area, since it only spans the empty square between the tensile straps (this is where the "cube pillows" come in, and here it is optimal). For regular opaque walls this span is 1-2" or 2-4 cm, but for 'transparent' walls it might be as much as 4" or 10 cm to maximize transmissivity.

Adding cells, making it more spherical (ie a cube) gets rid of this tendency to bulge, like those inflatable ottomans.

In the limit these are long cylindrical sections, so the hoop stress is twice the axial stress. The hoop straps are twice as thick accordingly, causing a 50% mass penalty for the tensile restraint. This isn't as bad as it sounds since it only scales with the volume enclosed by the hoop, not the total building volume, and also the pressure restraint layer is only a fraction of the total hoop assembly's mass.

BUT this buys you a 50% decrease in seam length (improving reliability), making inspection easier by replacing many four-way seams in isolated "rooms" with fewer long two-way seams in "hallways". It also makes the layout more flexible (since tensile interior walls are only needed in a single direction), and minimizes the number of rigid door frames needed to allow circulation through restraining walls.

However, in terms of radiation shielding, you have to generate more ISRU mass for the same quantity of shielding. Domes are the optimal shape for a shielded volume

Are you sure about that?

Counterexample time. Let's say your domes get very popular and you start tiling these X meter tall domes across a flat Martian plain, using hex tiling for the tightest possible packing. You say this is optimal. And yet I can improve on this configuration! If I take the same quantity of regolith per hectare and arrange it into a flat slab X meters off the ground covering a large hab, I've simultaneously A) made the rad shield 81% thicker because it no longer has to follow the hump of the hemisphere "up and down," and B) increased the amount of shielded volume by 65% because the cellular hab takes up the full height everywhere.

If domes really were the optimal shape, how could such improvements be possible? I think you may have inadvertently asked/answered the wrong geometric optimization problem.

also in part because they are self-supporting and easy enough to build.

I can do it easier: simply pile cheap loose regolith on top with a crane, rather than needing to compress/sinter/sulfurcrete/icecrete/whatever that same regolith into rigid blocks and then laboriously (robot or human) assemble them into a self-supporting dome.

The hab can still be self-supported if unpressurized, since that's a separate design decision. But there's no need to spend anything "improving" large amounts of regolith for a simple rad shield. Just scrape it up, or blast some from the local gravel pit, or reuse convenient mining/tunneling waste. Whichever's cheapest on a particular site.

the more mass you have inside your habitat, pot plants, furniture etc the more shielding you get on top of that. So there is a bonus to having traditional concrete/brick internal structures.

...

The bonus of thick floors is that they double as shielding for the people below you. And there is plenty of regolith to sinter or glass or otherwise turn into bricks with very little production effort.


There is a bonus, but it's not worth it.

This design still has pot plants and furniture of course. The only mass I've deleted is the unneeded gravity structure, and compared to that, loose regolith will be vastly cheaper per-kg (and each kg so invested will shield the entire hab, not just the lower floors). Don't spend a dollar on steel to save a penny on dirt.


I don't think rigid material for internals will be a problem. NASA already has a machine that chomps the crew's garbage and turns it into plastic.

Ok, you have a supply of bulk raw plastic. Problem is that rearranging that plastic into a highly reliable hab is the hard/expensive part, not getting the plastic.

That's partly why my idea is to build and pre-test the habs on Earth first, and only later build them on Mars when the technology matures.

As for multi-cell designs, are you familiar with noded spheroid tank geometries (below)? They're used for partially-pressurised tanks, although they've fallen out of favour due to difficulty inspecting the nodes between the toroid sections.

Yes, that's a great example of the structures I'm describing! This particular layout also has the "big open void" problem though.

As for cellular structures, the Beijing Water Park is basically an empty box with fancy walls. Interconnected cells without a rigid framework would strain unevenly with the centre roof and floor of the box getting the most strain, and the outer cell corners more relaxed.

...The strapping of the exterior surface would have to be given some careful thought... the straps clustering around the centre since that's where there is the most strain. Probably have aluminium truss edges.

Those are true of the Beijing Water Park (which is essentially a gravity structure with a long span, mostly holding up its own dead load), but not of cellular pressure vessels. The "span" is only as wide as the cells themselves, the strain should be theoretically uniform throughout the volume, and the pressure forces will completely overwhelm the dead load even with regolith on top.

For the inflata-cube design, simply having cubic subdivisions on the inside makes the most sense. Other primitives don't lend themselves well to human-occupied rooms, no matter what architects would have us believe :P

Don't get me started on geodesic domes...

Having no subdivisions (just a grid of vertical posts/cables) would be even better than cubes imo. But again, why choose square subdivisions over simpler long rectangles? The small reduction in peripheral restraint mass doesn't seem to justify all the additional joints and assembly complexity.

Note that roof/floor trusses are conventionally laid out in long parallel rows, not in an "elegant" square grid.

The exterior mass required for insulation and protection from the Martian environment (abrasion, UV etc) would be approximately 1.4x that of a sphere of identical volume (sqrt 6: sqrt pi).

Again, I think you have to compare a tessellated grid of spheres to a large, flat cellular building (one such that total outer wall area << total outer roof/basement area). This counterexample shows that in the limit cellular buildings only require 0.60x as much mass for insulation and protection as the sphere, not 1.4x. Far from a 40% mass penalty, cellular habs enjoy a 40% mass savings!

Actually, a shade more than that since the cube faces are pillowing.

Likely true for the top and bottom, but I've been assuming the wall's thermal and protective layers can "shortcut" in area-minimizing straight lines (similar to how MLI is installed on satellites or the LEM).

I was going to mention this all when I covered thermal, but now seems as good a time as any. :D There's a rather unconventional solution: install the roof thermal insulation above the piled regolith shield. Now you have a huge thermal buffer that equilibriates at room temperature. Switchable insulation (essentially heated nickel hydride in an evacuated MLI blanket (https://www.nrel.gov/docs/legosti/old/5814.pdf), needed since regular MLI works poorly in the Mars atmosphere; see also Quest Thermal's ME-MLI (https://sbir.nasa.gov/SBIR/abstracts/17/sbir/phase1/SBIR-17-1-Z10.01-9245.html)) could soak up daytime solar heat while insulating against cold night temperatures. Or vice-versa if thermal rejection is needed. It also means solar heat can be used to pre-warm this large thermal mass up to room temperature after installation.

Of course this does mean the insulation needs extra height to cover the regolith shield, but that penalty scales with building perimeter whereas the gain from shortcutting flat vs following the hoops scales with area. So again we find that scaling the building larger makes it get better.

Going back to radiation shielding materials, OLTARIS tells me that a 2m thick dome (well, sphere) on Mars reduces the radiation dosage inside to about 1/4 of the unshielded surface dose. So that's 20g/cm^2 of CO2, 200g/cm^2 of H2O and the surface blocking half the incident GCR is 300cm of regolith (this is modeled for backscatter).

Next I'll try with 200g/cm^2 of Martian regolith and then try a mix of 100g/cm^2 ice then 100g/cm^2 regolith to see what that does.

How does the 2m thick sphere compare with my 3.62m thick infinite horizontal slab? 2m infinite slab? In general what thickness of slab provides equivalent shielding to a 2m sphere?

My geometric intuition says it's <3.62m, which would imply that large flat slabs, not hemispheres, are the optimal shape for city-size radiation shields.

Don't forget that the gravity on Mars is only 0.38 g. Walking will be a slow and cautious affair if you don't want to hit the ceiling.

This video suggests otherwise:

https://www.youtube.com/watch?v=LvnDIDqcfGI (https://www.youtube.com/watch?v=LvnDIDqcfGI)

This study (https://www.cosmos.esa.int/documents/1566003/1642202/eslab2017-abstract+31.pdf/c0afc11b-75f2-54bf-b418-6f35f52148bd) found no statistically significant difference in vertical head oscillation between 0.3g and 1g when walking at either 4 km/hr or 11.5 km/hr.

Honestly whether the floor-to-ceiling height should be 2.5 meters or 2.7 meters or 2.9 meters isn't a very interesting question to me. It's bikeshedding. I'll use 2.5 meters, and folks can use VR goggles to simulate a slightly taller room. ;) Sorry, but there's no real engineering requirement that you be able to play basketball in the hallways.


Having more vertically oriented habitats forcing the inhabitants to put effort into moving around could be quite imperative if you don't want to force them to strap themselves for two hours a day onto exercise machines.

Hence why I prefer multiple levels. That and "amortizing" the rad shield over more volume.

Thanks everyone. Really valuable insights! So far (and despite efforts to the contrary) I find no show-stoppers in the cellular concept.

edit: typos
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ice on 03/23/2019 02:59 pm
Yesterday Elon Musk visited Doyle Ryder Elementary school in Flint, Michigan and demonstrated a new video of SpaceX's Starship. Here are some (low quality as captured by a camera) render images from that presentation with Starship landing at Mars Base Alpha: New official renders of SpaceX Starship landing at Mars Base Alpha (https://www.humanmars.net/2019/03/new-official-renders-of-spacex-starship.html)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/26/2019 07:53 am
Interesting. The settlement is in a crater, up against a crater wall to reduce radiation and separated from the landing pads by several kilometres. One large geodesic dome for show and the rest are surface buildings of some kind. Some of those buildings are clearly repurposed Starships. The majority are very hard to make out but from what I can make out they appear to be solid domes with windows (like Alvernia Studios), varying to egg shapes which I think are good from a radiation shielding point of view. Further away from the geodesic dome are purpose-built buildings similar to what you see on Earth, the models probably purchased off of Turbosquid's sci-fi buildings collection. Solar panels are located in between pad and settlement, out of the crater shadow and using otherwise useless land.

It's almost like someone's been reading our posts, but I think this thread and the geodesic domes one has become a pretty good resource thanks to the calibre of discussion and contribution.

(https://3.bp.blogspot.com/-bqDKokp18Ko/XJVmpBegeJI/AAAAAAAADjM/k2BFm9_GQkYqpX1iR4o9YZdiq0LlXxPIACLcBGAs/s1600/Official%2Brender%2Bof%2BSpaceX%2BStarship%2Bapproaching%2BMars%2BBase%2BAlpha.jpg)

Alvernia Studios in Poland for reference.

(http://www.alvernia.com/wp-content/galleries/about-us/onas.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/26/2019 12:16 pm
So as I understand it, the big problem with domes is enough mass above your habitat to passively pressurize it, but enough support structure to keep the structure up if pressure is lost.

There is an era of earth architecture that has very similar constraints- Gothic Heavy stone construction for the glory of divinity.

A tall martian cathedral, with flying buttresses to  help keep the pressure in sideways, (and regular buttresses to keep it from falling in when unpressurized) would be an interesting take on a mars hab. Stain glass mosaic windows can be reinforced with something much stronger than glass in the space between differently colored tiles, while experimenting with the initial poor  glass quality we can expect out of local production. And it has presence, which is the reason  it developed out of the stone castle-type architecture of the middle ages.

How practical do you think a Martian Cathedral would be as a ground hab?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/26/2019 12:32 pm
So as I understand it, the big problem with domes is enough mass above your habitat to passively pressurize it, but enough support structure to keep the structure up if pressure is lost.

IMO, the issue is why you are doing that?

Why are you trying to force a compressive structure to act as a tensile container? Just... don't. Use a structure that's meant for the job. I don't understand why that's such a radical concept.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/26/2019 12:36 pm
So as I understand it, the big problem with domes is enough mass above your habitat to passively pressurize it, but enough support structure to keep the structure up if pressure is lost.

IMO, the issue is why you are doing that?

Why are you trying to force a compressive structure to act as a tensile container? Just... don't. Use a structure that's meant for the job. I don't understand why that's such a radical concept.
Because compressive structures are easy to construct locally, while tensile structures will require imports for longer.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/26/2019 12:38 pm
So as I understand it, the big problem with domes is enough mass above your habitat to passively pressurize it, but enough support structure to keep the structure up if pressure is lost.

There is an era of earth architecture that has very similar constraints- Gothic Heavy stone construction for the glory of divinity.

A tall martian cathedral, with flying buttresses to  help keep the pressure in sideways, (and regular buttresses to keep it from falling in when unpressurized) would be an interesting take on a mars hab. Stain glass mosaic windows can be reinforced with something much stronger than glass in the space between differently colored tiles, while experimenting with the initial poor  glass quality we can expect out of local production. And it has presence, which is the reason  it developed out of the stone castle-type architecture of the middle ages.

How practical do you think a Martian Cathedral would be as a ground hab?

Domes are naturally self-supporting: they are arches. That's why so much premodern architecture uses it - and extraterrestrial habitat construction studies. St. Paul's Cathedral is 34m across, the top of the dome is 85m high. Florence Cathedral is 45m in diameter and the top of the dome is 115m high.

Passive pressurisation is not required, and generally a bad idea. You would need 15-20m of extremely compacted regolith directly overhead, and as you note would not passively pressurise the sides. There really is no need to do this. 6mm steel as used on the Starship would easily contain 1 bar of pressure in a 30m diameter dome (sphere, spotlight, whatever).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/26/2019 12:43 pm
Because compressive structures are easy to construct locally, while tensile structures will require imports for longer.

The policeman said, "So why are looking for them over here?"

The drunk replied, "Because the lighting's better."
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/26/2019 12:45 pm
So as I understand it, the big problem with domes is enough mass above your habitat to passively pressurize it, but enough support structure to keep the structure up if pressure is lost.

There is an era of earth architecture that has very similar constraints- Gothic Heavy stone construction for the glory of divinity.

A tall martian cathedral, with flying buttresses to  help keep the pressure in sideways, (and regular buttresses to keep it from falling in when unpressurized) would be an interesting take on a mars hab. Stain glass mosaic windows can be reinforced with something much stronger than glass in the space between differently colored tiles, while experimenting with the initial poor  glass quality we can expect out of local production. And it has presence, which is the reason  it developed out of the stone castle-type architecture of the middle ages.

How practical do you think a Martian Cathedral would be as a ground hab?

Domes are naturally self-supporting: they are arches. That's why so much premodern architecture uses it - and extraterrestrial habitat construction studies. St. Paul's Cathedral is 34m across, the top of the dome is 85m high. Florence Cathedral is 45m in diameter and the top of the dome is 115m high.

Passive pressurisation is not required, and generally a bad idea. You would need 15-20m of extremely compacted regolith directly overhead, and as you note would not passively pressurise the sides. There really is no need to do this. 6mm steel as used on the Starship would easily contain 1 bar of pressure in a 30m diameter dome (sphere, spotlight, whatever).

That reads to me like a 30-40m spire on top of the main arch, and flying buttresses capable of applying  similar resistance in compression to the sides. It's as much about the spectacle as it is the practicality.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/26/2019 12:47 pm
Because compressive structures are easy to construct locally, while tensile structures will require imports for longer.

The policeman said, "So why are looking for them over here?"

The drunk replied, "Because the lighting's better."
If I recall the whole joke, it hinges around there only being one object to find.
There is any number of solutions to the habitation problem. This is just an architectural style.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/26/2019 12:49 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/26/2019 12:52 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.
I understand that there are other options, that can be accomplished with less material. That's not the point.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/26/2019 12:56 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.
I understand that there are other options, that can be accomplished with less material. That's not the point.

Are you wanting a structure that is pretty or one that would be safe enough to raise children in?
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/26/2019 12:59 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.
I understand that there are other options, that can be accomplished with less material. That's not the point.

Are you wanting a structure that is pretty or one that would be safe enough to raise children in?
Ideally, both. Enough engineering margin can cover the safety aspect, but it takes a change in perspective to make an ugly building look good.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 03/26/2019 01:23 pm
So as I understand it, the big problem with domes is enough mass above your habitat to passively pressurize it, but enough support structure to keep the structure up if pressure is lost.

IMO, the issue is why you are doing that?

Why are you trying to force a compressive structure to act as a tensile container? Just... don't. Use a structure that's meant for the job. I don't understand why that's such a radical concept.
Because compressive structures are easy to construct locally, while tensile structures will require imports for longer.

Here we go again!...


Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/26/2019 01:25 pm
So as I understand it, the big problem with domes is enough mass above your habitat to passively pressurize it, but enough support structure to keep the structure up if pressure is lost.

IMO, the issue is why you are doing that?

Why are you trying to force a compressive structure to act as a tensile container? Just... don't. Use a structure that's meant for the job. I don't understand why that's such a radical concept.
Because compressive structures are easy to construct locally, while tensile structures will require imports for longer.

Here we go again!...
Yup!

Note that I'm not saying it's better. That seems to be the entirety of the objections, that there are better options. I'm asking if there are show stoppers to prevent someone from designing a building in this style.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 03/26/2019 02:24 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...

A local industrial base will be required to build anything more than a small research station.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/26/2019 04:22 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.
True and might be of use at some future point, but I fear it might be self limiting. Once a few tons have been collected how far do you have to travel to find more?

I suspect that Iron and steel processing will take a while to develop. Firstly they will want to focus on propellants, water and oxygen and food. They will also need a robust way of dealing with human waste that recycles as much as possible. After that plastics all of these materials will be produced/used in large quantities.

Eventualy iron and steel will be produced. However processing will be very different to what we see on Earth and on Mars Nickel might be favoured as it can be easily extracted using the Mond process
https://en.wikipedia.org/wiki/Mond_process (https://en.wikipedia.org/wiki/Mond_process)
The toxicity of Nickel carbonyl being much less of an issue on Mars than on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/26/2019 05:54 pm
I am just now envisioning little autonomous rover bots scouring Mars for iron meteorites in the not too distant future... Cool.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 03/26/2019 11:03 pm
Coming to the close of my teams design for the Mars Society Mars Colony Prize I can say this:
It is RIDICULOUSLY easy to make Mild Steel from the Martian soil if you have access to enough Methane.

Like, scarily easy.

Locally made steel pressure vessels will be the go for anything past 100 people. Think 'Artemis' except with Steel instead of Aluminium.

What form they take is up for debate/the architects though. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/27/2019 08:57 am
Quote
Are you wanting a structure that is pretty or one that would be safe enough to raise children in?
Ideally, both. Enough engineering margin can cover the safety aspect, but it takes a change in perspective to make an ugly building look good.

These engineering priorities are completely reversed. Enough cheap murals and/or VR (or massless "perspective change") can solve aesthetic concerns, but it takes a lot of heavy and expensive engineering margin to make a suboptimal hab design safe.


Note that I'm not saying it's better. That seems to be the entirety of the objections, that there are better options. I'm asking if there are show stoppers to prevent someone from designing a building in this style.


Based on that first sentence it seems we now agree that tensile restraint is in fact superior, so I won't rehash it.

Nothing stops anyone from designing a building of course, whether the design is lean and efficient or shockingly expensive. Actually establishing and operating a building on Mars is another matter entirely.

It just depends on which poison you feel like picking today: science fiction or science fact?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/27/2019 09:04 am
Coming to the close of my teams design for the Mars Society Mars Colony Prize I can say this:
It is RIDICULOUSLY easy to make Mild Steel from the Martian soil if you have access to enough Methane.

Like, scarily easy.

Locally made steel pressure vessels will be the go for anything past 100 people. Think 'Artemis' except with Steel instead of Aluminium.

What form they take is up for debate/the architects though.
Interesting. Do you have any further information or links for this?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/27/2019 09:12 am
Interesting. Do you have any further information or links for this?

It's called Direct Reduced Iron.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.660.8956&rep=rep1&type=pdf

https://pure.unileoben.ac.at/portal/files/576985/Plasma_Reduction_of_Iron_Oxide_by_Methane_Gas_and_its_Process_Up_scaling.pdf

Modern smelting operations eg in Australia use natural gas and fine iron ore sand to make steel with a lower carbon footprint than the coking method we all learned in school. The carbonyl method detailed in the first paper can make extremely high purity iron with relatively little energy input.

Just looking at the speed with which Texans with welders are throwing together Hopper and now Heart of Gold makes me think that steel will be very big in Martian construction.

A 30m diameter dome (sphere) made from 6mm steel plate would weigh 133 tonnes and have an interior volume of 14 137m^3. That's comfortably enough early-phase residential space for 100 people. Going back to Rakaydos' questions on using compressive strength to counter atmospheric pressure, the concrete base the bottom half of the sphere would have to be sunk into would help the hoop stresses in the lower half of the dome. Internal weight from the dome's fittings would also push it against the concrete, and there's less concern about punctures etc down there. Alternatively, an "observatory" style dome could be a sphere with regolith piled up to 15 metres around it, and extending 30m from the sphere rim with a resting slope angle of 30 degrees.

Iron is also more effective (or less bad) a radiation shielding material than you would think, because it's moderately effective at slowing neutrons - the bane of thick radiation shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/27/2019 10:15 am
Interesting. Do you have any further information or links for this?

It's called Direct Reduced Iron.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.660.8956&rep=rep1&type=pdf

https://pure.unileoben.ac.at/portal/files/576985/Plasma_Reduction_of_Iron_Oxide_by_Methane_Gas_and_its_Process_Up_scaling.pdf

Modern smelting operations eg in Australia use natural gas and fine iron ore sand to make steel with a lower carbon footprint than the coking method we all learned in school. The carbonyl method detailed in the first paper can make extremely high purity iron with relatively little energy input.

Just looking at the speed with which Texans with welders are throwing together Hopper and now Heart of Gold makes me think that steel will be very big in Martian construction.

A 30m diameter dome (sphere) made from 6mm steel plate would weigh 133 tonnes and have an interior volume of 14 137m^3. That's comfortably enough early-phase residential space for 100 people. Going back to Rakaydos' questions on using compressive strength to counter atmospheric pressure, the concrete base the bottom half of the sphere would have to be sunk into would help the hoop stresses in the lower half of the dome. Internal weight from the dome's fittings would also push it against the concrete, and there's less concern about punctures etc down there. Alternatively, an "observatory" style dome could be a sphere with regolith piled up to 15 metres around it, and extending 30m from the sphere rim with a resting slope angle of 30 degrees.

Iron is also more effective (or less bad) a radiation shielding material than you would think, because it's moderately effective at slowing neutrons - the bane of thick radiation shielding.

No doubt the methane plasma process could be made to work on Mars eventually but I don’t think it would be easy or quick. The first problem is the site of the initial base which will almost certainly be dictated by safety concerns and the presence of large amounts of water. The likelihood of also finding high purity iron ore (66% Fe) at this site is not good. The process might be adapted to use Martian regolith with much lower iron content, but who knows how successful that would be?

The other major obstacle is the very high electric power requirement for plasma arc furnaces of this sort and the problem of generating this power on Mars. Especially when there will be many other calls on this energy, such as ISRU for propellant production as well as the basic functioning of the base ECLSS etc.

However the carbonyl process mentioned in the paper does show great promise due to low energy usage, the ability to recycle the carbon monoxide and the ability to form the iron into component shapes by vapour deposition. If there is enough metallic iron on the surface in the form of meteorites and meteorite fragments this would be the way to go. It would also be a good way to recycle scrap steel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 03/27/2019 10:38 am
Hi folks,

Been following this great discussion for a while now.  Some really good ideas.

But I'm struck by a certain 'chicken or the egg' type problem.  Specifically, it seems as though there are going to be several synods worth of time (probably decades) wherein the first outposts established will be just for the purpose of preparing the infrastructure to accept actual long term settlers.  This includes initially things just involved in launch and landing of the Starship, such as ISRU based methalox production (which includes the whole water mining bit) and probably a type of paved landing/launch pad.  Then their efforts will move on to immediate life support (oxygen, water and food production, etc.) and then on to all of the other infrastructure needs (smelting, chemical plants, etc.) 

The problem is, I don't think any long term, permanent habitats (such as we have been discussing here) can be constructed until this last set of infrastructure tasks is completed.  Which again is probably decades after first landing.  So where do our 'outposters' live in the mean time. 

It seems to me they have to live in habs that are brought with them.  As such, they must be in a form that can easily be unloaded from the ship and easily deployed.

What is the general thinking on the form of these habitats?  Thanks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/27/2019 11:12 am
No doubt the methane plasma process could be made to work on Mars eventually but I don’t think it would be easy or quick. The first problem is the site of the initial base which will almost certainly be dictated by safety concerns and the presence of large amounts of water. The likelihood of also finding high purity iron ore (66% Fe) at this site is not good. The process might be adapted to use Martian regolith with much lower iron content, but who knows how successful that would be?

The other major obstacle is the very high electric power requirement for plasma arc furnaces of this sort and the problem of generating this power on Mars. Especially when there will be many other calls on this energy, such as ISRU for propellant production as well as the basic functioning of the base ECLSS etc.



Ignore the second paper, that was just an alternative production method. Methane reduction is widely used today - without plasma arcs. The DRI shaft process takes electricity, iron ore, natural gas and oxygen as inputs. There's also the rotary hearth process which involves some thermal coal as well.

The main advantage of the carbonyl method is that it seems to not need an electric arc furnace (requiring magnesite) after reduction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/27/2019 11:50 am
Hi folks,

Been following this great discussion for a while now.  Some really good ideas.

But I'm struck by a certain 'chicken or the egg' type problem.  Specifically, it seems as though there are going to be several synods worth of time (probably decades) wherein the first outposts established will be just for the purpose of preparing the infrastructure to accept actual long term settlers.  This includes initially things just involved in launch and landing of the Starship, such as ISRU based methalox production (which includes the whole water mining bit) and probably a type of paved landing/launch pad.  Then their efforts will move on to immediate life support (oxygen, water and food production, etc.) and then on to all of the other infrastructure needs (smelting, chemical plants, etc.) 

The problem is, I don't think any long term, permanent habitats (such as we have been discussing here) can be constructed until this last set of infrastructure tasks is completed.  Which again is probably decades after first landing.  So where do our 'outposters' live in the mean time. 

It seems to me they have to live in habs that are brought with them.  As such, they must be in a form that can easily be unloaded from the ship and easily deployed.

What is the general thinking on the form of these habitats?  Thanks.
The very first habitats will be the Starships themselves plus some modular additions that can be carried as cargo. There will need to be at least one and probably several un-crewed robot Starships landed near each other to bring all of the paraphernalia that will be required. If the first base construction crew to land can build some landing pads, with luck, after a few synods they will have 3 or more Starships in close proximity possibly linked by inflatable tunnels with smaller experimental habitat modules as well perhaps a small inflatable dome and some other prefab units.

But the focus will be on all of the other stuff they will need starting with as many solar panels and batteries as they can afford the space and mass for, an ISRU propellant plant with water mining kit, a rover or two, scientific kit and initially at least lots and lots of consumables also things like spacesuits, spare spacesuits and spacesuit spares etc etc etc

After that basic base is established they will have to consider their priorities for the next ships coming in a large 3d printer, sewage treatment equipment, lots more solar power and perhaps some hydroponics modules and all kinds of experimental set ups to test how to make everything from concrete and bricks to plastics and steel. So the initial habitat might not grow that quickly initially as there will be huge competition for cargo space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 03/27/2019 12:35 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...

A local industrial base will be required to build anything more than a small research station.

That is the wrong end of a simple cart before the horse discussion. Have you ever seen a foundry or steel mill? Or the major industries that feed one?  I'd argue that only crude oil production and handling is larger in scope than metals mining and milling. Those two industries are literally at the pinnacle of heavy industries because they are wildly resource and labor intensive.

Because of this, foundries and mills on Mars will be the last thing that occurs there, not the first, and certainly they will not be on the critical path to founding a colony because you need a major colony with infrastructure and population in place to support mining and milling operations. 

I will concede that metal working and fabrication facilities are required for constructing and supporting large scale buildings, but those are different specialized industries. They can utilize purified, but unmilled raw metals sent from Earth in various sizes on cargo ships- kind of like we do on Earth...




Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/27/2019 01:02 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...

A local industrial base will be required to build anything more than a small research station.

That is the wrong end of a simple cart before the horse discussion. Have you ever seen a foundry or steel mill? Or the major industries that feed one?  I'd argue that only crude oil production and handling is larger in scope than metals mining and milling. Those two industries are literally at the pinnacle of heavy industries because they are wildly resource and labor intensive.

Because of this, foundries and mills on Mars will be the last thing that occurs there, not the first, and certainly they will not be on the critical path to founding a colony because you need a major colony with infrastructure and population in place to support mining and milling operations. 

I will concede that metal working and fabrication facilities are required for constructing and supporting large scale buildings, but those are different specialized industries. They can utilize purified, but unmilled raw metals sent from Earth in various sizes on cargo ships- kind of like we do on Earth...

Iron and steel production on Mars will look very different from that on Earth. It will be at a different scale will be driven by different requirements  and will use different chemical processes. That said Iron and Steel production on Mars will almost certainly not be high up on the adgenda for a long time, although scrap recycling might, epecialy using the low energy carbonyl process.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/27/2019 02:08 pm

A 30m diameter dome (sphere) made from 6mm steel plate would weigh 133 tonnes and have an interior volume of 14 137m^3. That's comfortably enough early-phase residential space for 100 people. Going back to Rakaydos' questions on using compressive strength to counter atmospheric pressure, the concrete base the bottom half of the sphere would have to be sunk into would help the hoop stresses in the lower half of the dome. Internal weight from the dome's fittings would also push it against the concrete, and there's less concern about punctures etc down there. Alternatively, an "observatory" style dome could be a sphere with regolith piled up to 15 metres around it, and extending 30m from the sphere rim with a resting slope angle of 30 degrees.


Marsteel is nice and practical, but hemispheres still have structural problems.

A 30 meter diameter hemisphere needs a concrete/marscrete slab with sufficient bending moment and strength to avoid being ripped apart by the >25,000 kN (>2500 tonnes-force) which pulls up on the perimeter, while the same force pushes down across the entire concrete floor area. The 133 tonne dome on Mars will weigh 500 kN (50 tonnes-force), and perhaps several times that weight for the anchors and concrete footer, but it changes the force diagram very little. Functionally the weight is irrelevant, and it's just a pressure vessel with a flat concrete end cap (yes it's possible, but reactor containment vessels ain't exactly cheap).

Huge piles of regolith around the perimeter have the same basic problem. You need a structural floor with enough bending strength to transfer the load from the hemisphere outward into the pile, then transferred upwards into the regolith in a cone shape. If the entire 30 meter wide gravity pile is to be used, it needs a 30 meter structural floor projecting out from the rim of the dome, 8x larger area than the interior concrete floor. Or it needs even more regolith on top, when it's already using enough to rad shield three similar-sized buildings. I know regolith is cheap, but dirt and dirt moving isn't free even on Earth.

So you can do all that, or... just finish the other half of the tensile pressure vessel. :) Pressure vessels can be scaled as needed, so the exact same quoted performance numbers -- 133 tonnes of steel for 14 137 m³ of interior volume -- apply even after the radical simplification of deleting all the costly non-tensile elements! "It seems perfection is achieved not when there is nothing more to add, but when there is nothing left to take away."

[hobby horse] Of course large spheres may require additional site excavation, a point which favors cellular habs. :) That same 133 tonnes of steel (or a little more), a cellular hab will have the same volume but at least 8x the usable floorspace. And it allows you to delete the concrete/marscrete, the rebar, the large anchors, and whatever internal structure is planned to utilize the full height. You get the entire pressure restraint in a steel budget that's less than the hemisphere + anchors + rebar. This high economy is only possible because cellular arrangements can be spherical on the cell scale to optimize mass efficiency (this avoids having flat slabs act as single long spans), but rectilinear on the whole-building scale for ease of internal layout. [/hobby horse]

Gravity is weak whereas pressure is strong (in this case). Mars buildings should be pressure vessels first and gravity structures second, not the other way around. Philosophically it's like packing a car: biggest items first, then fit the smaller stuff around it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 03/27/2019 02:37 pm
The issues with both pressure and production of native construction materials seems to strongly militate towards tunnelled structures, rather than surface constructions.  It may be far easier, at least at the start, to drive a tunnelling machine into some convenient rock and then seal it, rather than bring suitable construction material to Mars, or create the infrastructure to make such material.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/27/2019 03:09 pm
The issues with both pressure and production of native construction materials seems to strongly militate towards tunnelled structures, rather than surface constructions.  It may be far easier, at least at the start, to drive a tunnelling machine into some convenient rock and then seal it, rather than bring suitable construction material to Mars, or create the infrastructure to make such material.
Or just pile enough rock to overcome the pressure differential.

Because if theres ONE thing Mars has plentiful amounts of, it's rock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 03/27/2019 03:29 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...

A local industrial base will be required to build anything more than a small research station.

That is the wrong end of a simple cart before the horse discussion. Have you ever seen a foundry or steel mill? Or the major industries that feed one?  I'd argue that only crude oil production and handling is larger in scope than metals mining and milling. Those two industries are literally at the pinnacle of heavy industries because they are wildly resource and labor intensive.

Because of this, foundries and mills on Mars will be the last thing that occurs there, not the first, and certainly they will not be on the critical path to founding a colony because you need a major colony with infrastructure and population in place to support mining and milling operations. 

I will concede that metal working and fabrication facilities are required for constructing and supporting large scale buildings, but those are different specialized industries. They can utilize purified, but unmilled raw metals sent from Earth in various sizes on cargo ships- kind of like we do on Earth...

Foundry doesn't mean a steel making industrial complex that can supply the needs of a nation. The word doesn't imply the size of the facility, it's the purpose. Think of it as the Mars version of a blacksmith's shop. Build what you need for local construction. Melt down some nickle-iron meteorites and pour into a mold.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Northern Sky on 03/27/2019 03:31 pm
I recently saw that Caterpillar and PON (a major European CAT distributor) teamed up to develop a fully electric excavator. It's a 25 ton machine, the base model of which is normally powered by a diesel engine, but which they have converted by replacing the diesel with an electric motor of equivalent power, and a lithium battery pack to power it. The battery pack gives enough power for over 7 hours of run time per charge. Battery-electric mini excavators have been made before, and large ones with an external power cord for use in mines, but this is the first time I've seen a large (not huge, like a mining machine, but not a mini either) machine that is battery electric.

https://www.youtube.com/watch?v=GEXgcXtC1sQ

The first thought into my head when I saw it was "machines like this are made for Mars work."

Obviously the machine in question was not designed with mars colonization in mind - it was designed to illustrate that large construction equipment could be run off a battery with zero emissions, as part of a co2 reduction effort - but it also in so doing gave an example of the kind of machine that could be used on Mars. I guess, a lot of different kinds of machines... excavators, loaders, dozers, scrapers, cranes, mixers etc. that are used today on earth, would also work on mars pretty well if you swap out the diesel engine for an electric motor, and put a big lithium pack on it.

Just a thought.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/27/2019 03:50 pm
The issues with both pressure and production of native construction materials seems to strongly militate towards tunnelled structures, rather than surface constructions.  It may be far easier, at least at the start, to drive a tunnelling machine into some convenient rock and then seal it, rather than bring suitable construction material to Mars, or create the infrastructure to make such material.
Depends on the cost of the sealant and the quality of the rock.  Most tunnels, pressure tunnels in particular, have liners, so if liners are required we're more or less back to the same solution as surface habs with piled up rock.

Most surface rock is not good rock.  Surface rock is broken up by weather and geological processes and full of fractures.  for Mars and the Moon, meteorites have probably broken up most of the surface rock over time into boulders and fractured stuff that may not be all that pressure proof.
Although ice might serve as a good cement, we really have to go and see before we can decide anything on this.

So best not to plan on tunnels too soon.  Start with imported pressure vessels, buried or with ice/water walls.  Explore, find adequate resources (rock, sandstone, monolithic ice, whatever), make some small pilot plants and test installations and see what works.

Then you can open up the industrial machine and start scaling at whatever speed your funds allow you to do and your transportation infrastructure allows you to move.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/27/2019 03:50 pm
There are loads of threads on Mars ISRU and plenty of posts in this one about it. Let's not reinvent the wheel. I'd like to hear about people's ideas for cool-looking habitats, no matter what tech level they're at.
Title: Re: Envisioning Amazing Martian Habitats
Post by: uhuznaa on 03/27/2019 03:53 pm
If you can make steel, spiral-winding and welding big and long tubes (with hemispherical end caps) would be a much better choice than domes. Easier to make, a cylinder is much more mass-efficient for pressure vessels and even piling regolith on top of a horizontal tube is easier than piling it on top of a high dome. You could first dig a trench to bury if to half height and then pile regolith on top of it for protection and insulation.

Piling up regolith for compensating internal pressure won't be easy. At a density of 1.5 g/cm3 and 0,38 g you would need to pile up about 18 m of regolith on top of your pressure vessel to counter an internal pressure of one atmosphere. Boring into a sandstone cliff (if there's one around) might indeed be easier than that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/27/2019 04:00 pm
The issues with both pressure and production of native construction materials seems to strongly militate towards tunnelled structures, rather than surface constructions.  It may be far easier, at least at the start, to drive a tunnelling machine into some convenient rock and then seal it, rather than bring suitable construction material to Mars, or create the infrastructure to make such material.

Bingo, we have a winner.

...And that's what quite a few have been saying in this thread dating back to ... years ago.

You don't bring the building materials to Mars. You bring the building machinery.

The bedrock is there to be hollowed out by roadheaders and TBM's.

Domes, spheres and bouncy castles, sorry, tensile structures, are too import-intensive for the early years when every kilo brought to Mars must be used to produce the basics for survival.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 03/27/2019 04:06 pm
If you can make steel, spiral-winding and welding big and long tubes (with hemispherical end caps) would be a much better choice than domes. Easier to make, a cylinder is much more mass-efficient for pressure vessels and even piling regolith on top of a horizontal tube is easier than piling it on top of a high dome. You could first dig a trench to bury if to half height and then pile regolith on top of it for protection and insulation.

Piling up regolith for compensating internal pressure won't be easy. At a density of 1.5 g/cm3 and 0,38 g you would need to pile up about 18 m of regolith on top of your pressure vessel to counter an internal pressure of one atmosphere. Boring into a sandstone cliff (if there's one around) might indeed be easier than that.

Put windows on the end caps of cylinders if you want a nice view. Depending on the size of the cylinder, say multiple levels, this could be a nice park area.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/27/2019 04:10 pm
The issues with both pressure and production of native construction materials seems to strongly militate towards tunnelled structures, rather than surface constructions.  It may be far easier, at least at the start, to drive a tunnelling machine into some convenient rock and then seal it, rather than bring suitable construction material to Mars, or create the infrastructure to make such material.

Bingo, we have a winner.

...And that's what quite a few have been saying in this thread dating back to ... years ago.

You don't bring the building materials to Mars. You bring the building machinery.

The bedrock is there to be hollowed out by roadheaders and TBM's.

Domes, spheres and bouncy castles, sorry, tensile structures, are too import-intensive for the early years when every kilo brought to Mars must be used to produce the basics for survival.

I propose we create separate threads for tunnelling vs surface construction and imports vs local materials.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/27/2019 04:27 pm
Nah, I think we can stick to one thread, this one. I love reading about all the different ideas for Mars habitats and I am happy to find it all in one place.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/27/2019 04:30 pm
I recently saw that Caterpillar and PON (a major European CAT distributor) teamed up to develop a fully electric excavator. It's a 25 ton machine, the base model of which is normally powered by a diesel engine, but which they have converted by replacing the diesel with an electric motor of equivalent power, and a lithium battery pack to power it. The battery pack gives enough power for over 7 hours of run time per charge. Battery-electric mini excavators have been made before, and large ones with an external power cord for use in mines, but this is the first time I've seen a large (not huge, like a mining machine, but not a mini either) machine that is battery electric.

https://www.youtube.com/watch?v=GEXgcXtC1sQ

The first thought into my head when I saw it was "machines like this are made for Mars work."

Obviously the machine in question was not designed with mars colonization in mind - it was designed to illustrate that large construction equipment could be run off a battery with zero emissions, as part of a co2 reduction effort - but it also in so doing gave an example of the kind of machine that could be used on Mars. I guess, a lot of different kinds of machines... excavators, loaders, dozers, scrapers, cranes, mixers etc. that are used today on earth, would also work on mars pretty well if you swap out the diesel engine for an electric motor, and put a big lithium pack on it.

Just a thought.

Thanks, it looks great!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 03/27/2019 04:42 pm
Most surface rock is not good rock.  Surface rock is broken up by weather and geological processes and full of fractures.  for Mars and the Moon, meteorites have probably broken up most of the surface rock over time into boulders and fractured stuff that may not be all that pressure proof.
If it is just a matter of airtight sealing (and not structural lining), then some sort of plastic made from the methane feedstock might do.  I don't know how complex the industrial equipment to produce that would be, but it would be using material already being generated (methane), rather than having to mine materials for ore or concrete.  I'm thinking of something one could just spray on the exposed rock to form a seal.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 03/27/2019 05:12 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...

A local industrial base will be required to build anything more than a small research station.

That is the wrong end of a simple cart before the horse discussion. Have you ever seen a foundry or steel mill? Or the major industries that feed one?  I'd argue that only crude oil production and handling is larger in scope than metals mining and milling. Those two industries are literally at the pinnacle of heavy industries because they are wildly resource and labor intensive.

Because of this, foundries and mills on Mars will be the last thing that occurs there, not the first, and certainly they will not be on the critical path to founding a colony because you need a major colony with infrastructure and population in place to support mining and milling operations. 

I will concede that metal working and fabrication facilities are required for constructing and supporting large scale buildings, but those are different specialized industries. They can utilize purified, but unmilled raw metals sent from Earth in various sizes on cargo ships- kind of like we do on Earth...

Foundry doesn't mean a steel making industrial complex that can supply the needs of a nation. The word doesn't imply the size of the facility, it's the purpose. Think of it as the Mars version of a blacksmith's shop. Build what you need for local construction. Melt down some nickle-iron meteorites and pour into a mold.

Your analogy is wrong.  A smithy is not mining and purifying iron and making steel. It is a metal working shop. I agree metal working shops and machine shops will be essential on Mars as I stated above.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/27/2019 06:20 pm
Piling up regolith for compensating internal pressure won't be easy. At a density of 1.5 g/cm3 and 0,38 g you would need to pile up about 18 m of regolith on top of your pressure vessel to counter an internal pressure of one atmosphere. Boring into a sandstone cliff (if there's one around) might indeed be easier than that.
It's just earthmoving. Or Stonemasonry, if you wanted to be fancy. People built structures with similar constraints with hand tools and muscle power.

You're right that there would need to be a lot of it, but that's not actually difficult.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 03/27/2019 06:40 pm
Quote from: rakaydos
You're right that there would need to be a lot of it, but that's not actually difficult.
Depends what you mean by difficult. Ok it doesn't at first sight appear to be an unsolvable engineering challenge....

However the mass and volume of the cover effectively go up as the square of the depth, (of a linear structure where we ignore the ends) unless it is constrained from spreading, by valley/trench/constructed walls. So quite quickly considerable volumes of rock/spoil etc are needed, meaning considerable energy, machinery, and even human time to move it... diverting all those from other projects, and therefore requiring more payload to Mars and/or longer installation times. Getting all of this together will tax not just logistics but engineering... even without more complicated access arrangements, maintenance obstruction .... So I contend it is actually difficult!
Edit: very many people built what you suggest (in the past) .... and they had different limitations than spacesuits, and finite electrical power for the excavators!
Title: Re: Envisioning Amazing Martian Habitats
Post by: GregTheGrumpy on 03/27/2019 07:02 pm
Nah, I think we can stick to one thread, this one. I love reading about all the different ideas for Mars habitats and I am happy to find it all in one place.

I second this.  Trying to find something when everything is so finely partitioned is a real pain.

I also think sub-surface construction is the way to go.  At first, I believe it will be tunnels sealed with marscrete (strength) walls with a plastic-like (impermeable) sealant.  The latter iterations may be wider and taller than the strict definition of a tunnel, but the idea is present.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 03/27/2019 07:11 pm
Isn't tunnelling essentially using pre-piled-up regolith?  If one needs to build a hill 18m high just to counteract pressure, doesn't it make more sense to find someplace that already has that much regolith and burrow into it?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/27/2019 07:37 pm
The issues with both pressure and production of native construction materials seems to strongly militate towards tunnelled structures, rather than surface constructions.  It may be far easier, at least at the start, to drive a tunnelling machine into some convenient rock and then seal it, rather than bring suitable construction material to Mars, or create the infrastructure to make such material.
Depends on the cost of the sealant and the quality of the rock.  Most tunnels, pressure tunnels in particular, have liners, so if liners are required we're more or less back to the same solution as surface habs with piled up rock.

Strongly disagree, and I'm super in favor of surface habs! Air sealing can be done with a thin film of plastic coated with aluminum oxide. The plastic is rather gas permeable, but the AlOx layer is not. This is much easier and less mass than creating a highly reliable tensile structure.

Again I do take it as a given that underground habs are possible. The open question is whether above-ground habs can be designed that are cheaper than underground ones.

If you can make steel, spiral-winding and welding big and long tubes (with hemispherical end caps) would be a much better choice than domes. Easier to make, a cylinder is much more mass-efficient for pressure vessels and even piling regolith on top of a horizontal tube is easier than piling it on top of a high dome. You could first dig a trench to bury if to half height and then pile regolith on top of it for protection and insulation.

This was actually the idea I started out with, before it evolved into a cellular hab. Roughly, the design evolution went:

1. If we have these long cylinders, we want to lay them out next to each-other to optimize space and save regolith. Space itself is obviously free (though a particular site may have topological or operational constraints), but utility runs, vehicle operations, and even simply walking time are not free, so compact layouts are preferable to sprawling ones.

2. Your regolith shield is quite thick compared to an individual tube, so stacking tubes on top of each-other saves rad shielding regolith per square meter. It also reduces heat loss per square meter. This can be good or bad depending on your thermodynamic assumptions, but I'm presuming that any hab waste heat will find ready use melting ice and warming greenhouses at night.

3. If you have a big stack of cylinders "mortared together" by regolith, why not just delete the regolith and save a bunch of steps? It makes interconnections between rooms much simpler (doorways instead of connecting tunnels), it makes the completed building much less massive, and it places all the shielding regolith on the top / sides where it can do the most good by shielding the entire volume not just ~half (on average). As you point out, the regolith radiation shield can also act as insulation, thermal mass, a UV barrier, and an impact shield.

Edit: nitpick, but a cylindrical pressure vessel made from isotropic material like steel is twice as heavy as a sphere, not "more mass-efficient." A cylinder made of anisotropic material like carbon/basalt fiber is 1.5x as heavy.

The issues with both pressure and production of native construction materials seems to strongly militate towards tunnelled structures, rather than surface constructions.  It may be far easier, at least at the start, to drive a tunnelling machine into some convenient rock and then seal it, rather than bring suitable construction material to Mars, or create the infrastructure to make such material.

Bingo, we have a winner.

...And that's what quite a few have been saying in this thread dating back to ... years ago.

You don't bring the building materials to Mars. You bring the building machinery.

A factory that builds habs from continuous basalt fiber is also "building machinery," so it fits your rule. And such a factory can produce vastly more habitable volume per kg of Mars atoms processed (by a factor of roughly 400x) than a roadheader + film air bladder + everything else needed to turn an empty rock tunnel into a functioning hab. The question is, which set of machines/methods for rearranging Martian atoms into habs is cheaper?

The bedrock is there to be hollowed out by roadheaders and TBM's.

Domes, spheres and bouncy castles, sorry, tensile structures, are too import-intensive for the early years when every kilo brought to Mars must be used to produce the basics for survival.

Sorry, but the roadheader is just the beginning of an underground hab production supply chain. The plan will involve bringing habs (including quick setup inflatable habs) as a transitional phase between living in Starship and developing Mars manufacturing to the level that most hab parts can be made on Mars. That will take decades.

If your Mars surface hab R&D plan is "wait until we're on Mars before building the first testing hab on Mars," it will unnecessarily delay hab reliability / functional tests by decades. This is a mistake imo.

And for what? The philosophical purity of not bringing any hab parts from Earth? It seems like an unnecessary and undesirable rule to impose on oneself from square one. Why put this straightjacket on before starting a the part-by-part analysis on whether ISRU or imports will be cheaper? "Transport from Earth is expensive" seems a thin justification for such a sweeping generalization about all conceivable materials and every ISRU production technique, since that means that all production equipment is also costly to import.

Compressed regolith blocks will be cheaper to make on Mars, for obvious and uncontroversial reasons. Microchips will be cheaper to make on Earth for obvious and uncontroversial reasons. So it's not clear to me that all imported material will always be more costly. It is certainly not obvious that importing hab material should be shunned at all cost (or indeed, at any cost beyond the shipping cost).

Don't think of importing prefab parts as merely importing mass. It's more than that. Think of it as importing all the "virtual labor" from the entire supply chain that was needed to mine and refine and manufacture and assemble and inspect and test those prefab parts. Except you can leave the heavy supply chain and life support needed for that labor all back on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/27/2019 07:42 pm
Piling up regolith for compensating internal pressure won't be easy. At a density of 1.5 g/cm3 and 0,38 g you would need to pile up about 18 m of regolith on top of your pressure vessel to counter an internal pressure of one atmosphere. Boring into a sandstone cliff (if there's one around) might indeed be easier than that.
It's just earthmoving. Or Stonemasonry, if you wanted to be fancy. People built structures with similar constraints with hand tools and muscle power.

You're right that there would need to be a lot of it, but that's not actually difficult.

See how far that argument gets you while negotiating with your bulldozer guy.  ;D

Point is, it doesn't have to be difficult to be expensive. And more earthmoving is more expensive than less earthmoving.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/27/2019 08:28 pm

However the mass and volume of the cover effectively go up as the square of the depth, (of a linear structure where we ignore the ends) unless it is constrained from spreading, by valley/trench/constructed walls. So quite quickly considerable volumes of rock/spoil etc are needed, meaning considerable energy, machinery, and even human time to move it...

Well said. This is also a great argument for the aforementioned "Step 1" in my design's evolution (one single buried cylinder -> a row of buried cylinders). If you lay many cylinders side-by-side then the regolith shield mass scales linearly with depth, rather than as the square.

I did say it would "save regolith," but you articulated it much better. :)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/27/2019 08:52 pm
Re: Tunnelling vs...

In the real world, well at least on this world, cut'n'cover is preferred over tunnelling any time you can get access from above. Even then, an open-cut, wide slope-sided trench is preferred when working at a green-field site; narrow, straight-walled cut'n'cover is only resorted to when you are constrained by existing infrastructure. The volume of material moved is not the constraint. Earth-moving is the least expensive part of building.

But when you have the choice, building above-ground wins over everything else. (Just... no domes.)

Hence, IMO, IFF you need to cover your habs with regolith because of radiation, you'll use earthmoving and wide slope-sided trenches, not tunnelling, nor narrow-trench cut'n'cover.

If it turns out you don't need the radiation protection, you will stay on the surface. You won't use regolith for counter-mass to air-pressure.

And tunnelling simply won't happen until it's required under the same circumstances it's required on Earth: you have to get under existing infrastructure, or to get through hard-to-bypass geology. And even when necessary, no-one will live in there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 03/27/2019 09:06 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...

A local industrial base will be required to build anything more than a small research station.

That is the wrong end of a simple cart before the horse discussion. Have you ever seen a foundry or steel mill? Or the major industries that feed one?  I'd argue that only crude oil production and handling is larger in scope than metals mining and milling. Those two industries are literally at the pinnacle of heavy industries because they are wildly resource and labor intensive.

Because of this, foundries and mills on Mars will be the last thing that occurs there, not the first, and certainly they will not be on the critical path to founding a colony because you need a major colony with infrastructure and population in place to support mining and milling operations. 

I will concede that metal working and fabrication facilities are required for constructing and supporting large scale buildings, but those are different specialized industries. They can utilize purified, but unmilled raw metals sent from Earth in various sizes on cargo ships- kind of like we do on Earth...

Foundry doesn't mean a steel making industrial complex that can supply the needs of a nation. The word doesn't imply the size of the facility, it's the purpose. Think of it as the Mars version of a blacksmith's shop. Build what you need for local construction. Melt down some nickle-iron meteorites and pour into a mold.

Your analogy is wrong.  A smithy is not mining and purifying iron and making steel. It is a metal working shop. I agree metal working shops and machine shops will be essential on Mars as I stated above.

You're using the wrong definition of foundry. As per Oxford Dictionary: A workshop or factory for casting metal. If nickle-iron as a source material would be sufficient for construction, as in melt and pour into molds, then the equipment needed can be brought with the rest of the workshop.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/27/2019 09:54 pm
Twark_Main, thanks for your long and very well-written reply. I'm on my phone so I'll be shorter.

I didn't realise that your hab textile could be made with ISRU. Interesting. I'd like to see more info on basalt fibres and how well they work for big tensile structures.

Your habs would still need a huge pile of regolith on top, wouldn't they?

My vision for the first years of a Mars base is that fuel and oxygen production takes place in a turn-key readymade factory installed in a Starship. Another Starship brings tunnelling equipment and a third brings the crew in what will serve as their hab until tunnels are made.

The one place where I believe that an inflatable structure would come in handy would be for the tunnel airlock.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 03/27/2019 11:03 pm
Raw iron is available just lying around on Mars in the form of nickel-iron meteorites.

Iron foundries are not...

A local industrial base will be required to build anything more than a small research station.

That is the wrong end of a simple cart before the horse discussion. Have you ever seen a foundry or steel mill? Or the major industries that feed one?  I'd argue that only crude oil production and handling is larger in scope than metals mining and milling. Those two industries are literally at the pinnacle of heavy industries because they are wildly resource and labor intensive.

Because of this, foundries and mills on Mars will be the last thing that occurs there, not the first, and certainly they will not be on the critical path to founding a colony because you need a major colony with infrastructure and population in place to support mining and milling operations. 

I will concede that metal working and fabrication facilities are required for constructing and supporting large scale buildings, but those are different specialized industries. They can utilize purified, but unmilled raw metals sent from Earth in various sizes on cargo ships- kind of like we do on Earth...

From my analysis, the reason the steel production industry and buildings are so big/heavy isn't because of the nature of Steel itself, but because the production volume you need to deal with.

A small mini-steel foundry on earth can produce upwards of 300,000 tonne of steel a year, one on Mars may only have to produce 12,000 tonne, or 4% of that, per year from the soil, to build a settlement for over a thousand people in 1 synod, which is possible over kill. Full sized Steel Mills can be as big as 3,000,000 tonnes per year.

Additionally, a lot of processes on Earth are heavy and big not because they have to be, but because it's cheaper. Somethings going to break? We could optimise the structure or use more advance materials...or just make it thicker!

Getting your hands on Iron Oxide on Mars is literally just a matter of passing the dirt through a Magnetic Separator . The fines are already the right size for small, commercially available ones, you don't even need to crush it, just sieve it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 03/28/2019 03:40 am
Random observation: perhaps Starship hulls will be available for use on the surface for longer than is assumed, in fact almost perpetually.

My argument is that there will always be a stream of Starship hulls being retired on mars, so why not use them?
There are a couple of reasons why I think retiring the hulls on mars makes more sense, including the fact that you are sending more mass to mars than bringing home, and it saving the colony the effort of all that ISRU that could be used to grow the colony.

Some people really like tunnelling. So perhaps that is the only technology you develop on Mars.. but your city surface could be dotted with cannibalised Starship hulls that give you an above ground viewing area. Also the hulls could come first with the underground infrastructure coming later.

Maybe someone can estimate the ratio between colonists and discarded hulls? Even without deciding how much volume/colonist is below ground, that (plus solar power requirements per colonist) could give an indication of what the above ground portion would look like for a town of a certain population.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 03/28/2019 04:47 am
Maybe some cargo Starships could be specifically built as hab towers.

Instead of one or two cargo bays the ship would have accommodation rooms on multiple levels
that would be packed full of non bulky cargo for the trip out.  Once landed and unloaded
it becomes an apartment block.

Some form of motorised dolly that attaches to the tip of each fin would be useful for moving
these habs from the landing site to the residential area where they would be connected to the
base power, water etc.  Would be better than having to run cabling and piping all over the
landscape to each ship where it landed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CraigLieb on 03/28/2019 09:31 am
 On Mars certain types of materials could be very hard to come by, so nothing should be wasted.
Some ships that end up retired on Mars could be mined/scavenged for raw materials. Consideration can be applied for easier recycling or reuse, including the ability to separate different material types from each other at end of life. For example one can create plugable modules instead of permanently bonding dissimilar items together. It is counter intuitive to add fastener systems, grow part count and complexity. However it can mean the difference beteeen a useful collection of raw materials (separable plastics metals, cloth, composites, wood, electrical components) or a useless hunk of junk that gets set aside in a pile.  Field repairability may require the same considerations.  Aircraft end-of-life recycling tech has progressed, driving this as a (secondary) design criteria. Cradle-to-Cradle is an excellent book on this subject.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/28/2019 10:53 am
Maybe some cargo Starships could be specifically built as hab towers.

Instead of one or two cargo bays the ship would have accommodation rooms on multiple levels
that would be packed full of non bulky cargo for the trip out.  Once landed and unloaded
it becomes an apartment block.

This seems to be reflected in the Flint Kids video. The artists placed a couple of Starships horizontally as "barracks."

As Paul451 says, cut n cover is always preferred over tunnel boring. Elon's Boring Company tunnels are bored because there is street infrastructure overhead. Otherwise, it's simpler to remove overburden and put it back over something solid.

I've already detailed the problems around Martian tunnel boring, but I'll sum them up.

1. Bedrock must be fracture free to have a chance of being airtight. Generally this only occurs 50m down. On Mars, bedrock appears fractured down to 100m. Otherwise a marscrete etc lining is a requirement.
2. Only 5-10m of regolith is required to cut out virtually 100% of radiation.
3. Rock pressure comes in at the sides, not over the top as most people assume. Tunnels are squeezed laterally by the rock on either side.
4. On Earth, every site is unique and delays will be encountered. On Mars, this is even more true.

Sedimentary rocks on Mars are also incredibly porous, which makes them easy to tunnel through but virtually impossible to make airtight without a liner.

https://www.theweek.in/news/sci-tech/2019/02/02/Rover-Curiosity-finds-Mars-rocks-more-porous-than-thought.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/28/2019 12:32 pm


Maybe some cargo Starships could be specifically built as hab towers.

Instead of one or two cargo bays the ship would have accommodation rooms on multiple levels
that would be packed full of non bulky cargo for the trip out.  Once landed and unloaded
it becomes an apartment block.

This seems to be reflected in the Flint Kids video. The artists placed a couple of Starships horizontally as "barracks."

As Paul451 says, cut n cover is always preferred over tunnel boring. Elon's Boring Company tunnels are bored because there is street infrastructure overhead. Otherwise, it's simpler to remove overburden and put it back over something solid.

I've already detailed the problems around Martian tunnel boring, but I'll sum them up.

1. Bedrock must be fracture free to have a chance of being airtight. Generally this only occurs 50m down. On Mars, bedrock appears fractured down to 100m. Otherwise a marscrete etc lining is a requirement.
2. Only 5-10m of regolith is required to cut out virtually 100% of radiation.
3. Rock pressure comes in at the sides, not over the top as most people assume. Tunnels are squeezed laterally by the rock on either side.
4. On Earth, every site is unique and delays will be encountered. On Mars, this is even more true.

Sedimentary rocks on Mars are also incredibly porous, which makes them easy to tunnel through but virtually impossible to make airtight without a liner.

https://www.theweek.in/news/sci-tech/2019/02/02/Rover-Curiosity-finds-Mars-rocks-more-porous-than-thought.html

There are valid counter-arguments to these.

A liner is much simpler than a solid tube, since it is not structural - it can be sprayed on, and let it cure inside those crack of porous paths.

If you need to dig until you have 10 m above the top of the tube you want to build inside the trench, that's a very deep trench - not quite "trench and bury".  15 m deep?  20 m?

Tunnels remain horizontal as you dig into a hill side, giving you depth for free.  Trenches can't do that.

Look online at images of Subtropolis.  If the digging is easy, scaling a tunnel system seems pretty straight forward.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Florent D on 03/28/2019 12:59 pm
Maybe some cargo Starships could be specifically built as hab towers.

Instead of one or two cargo bays the ship would have accommodation rooms on multiple levels
that would be packed full of non bulky cargo for the trip out.  Once landed and unloaded
it becomes an apartment block.

This seems to be reflected in the Flint Kids video. The artists placed a couple of Starships horizontally as "barracks."

As Paul451 says, cut n cover is always preferred over tunnel boring. Elon's Boring Company tunnels are bored because there is street infrastructure overhead. Otherwise, it's simpler to remove overburden and put it back over something solid.

I've already detailed the problems around Martian tunnel boring, but I'll sum them up.

1. Bedrock must be fracture free to have a chance of being airtight. Generally this only occurs 50m down. On Mars, bedrock appears fractured down to 100m. Otherwise a marscrete etc lining is a requirement.
2. Only 5-10m of regolith is required to cut out virtually 100% of radiation.
3. Rock pressure comes in at the sides, not over the top as most people assume. Tunnels are squeezed laterally by the rock on either side.
4. On Earth, every site is unique and delays will be encountered. On Mars, this is even more true.

Sedimentary rocks on Mars are also incredibly porous, which makes them easy to tunnel through but virtually impossible to make airtight without a liner.

https://www.theweek.in/news/sci-tech/2019/02/02/Rover-Curiosity-finds-Mars-rocks-more-porous-than-thought.html

https://www.universetoday.com/wp-content/uploads/2017/09/gallery-1506701650-mars.gif (https://www.universetoday.com/wp-content/uploads/2017/09/gallery-1506701650-mars.gif)

We see very well in the center of this .gif the presence of two SS, certainly planned for the firsts dwellings.

Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 03/28/2019 01:21 pm


Maybe some cargo Starships could be specifically built as hab towers.

Instead of one or two cargo bays the ship would have accommodation rooms on multiple levels
that would be packed full of non bulky cargo for the trip out.  Once landed and unloaded
it becomes an apartment block.

This seems to be reflected in the Flint Kids video. The artists placed a couple of Starships horizontally as "barracks."

As Paul451 says, cut n cover is always preferred over tunnel boring. Elon's Boring Company tunnels are bored because there is street infrastructure overhead. Otherwise, it's simpler to remove overburden and put it back over something solid.

I've already detailed the problems around Martian tunnel boring, but I'll sum them up.

1. Bedrock must be fracture free to have a chance of being airtight. Generally this only occurs 50m down. On Mars, bedrock appears fractured down to 100m. Otherwise a marscrete etc lining is a requirement.
2. Only 5-10m of regolith is required to cut out virtually 100% of radiation.
3. Rock pressure comes in at the sides, not over the top as most people assume. Tunnels are squeezed laterally by the rock on either side.
4. On Earth, every site is unique and delays will be encountered. On Mars, this is even more true.

Sedimentary rocks on Mars are also incredibly porous, which makes them easy to tunnel through but virtually impossible to make airtight without a liner.

https://www.theweek.in/news/sci-tech/2019/02/02/Rover-Curiosity-finds-Mars-rocks-more-porous-than-thought.html

There are valid counter-arguments to these.

A liner is much simpler than a solid tube, since it is not structural - it can be sprayed on, and let it cure inside those crack of porous paths.

If you need to dig until you have 10 m above the top of the tube you want to build inside the trench, that's a very deep trench - not quite "trench and bury".  15 m deep?  20 m?

Tunnels remain horizontal as you dig into a hill side, giving you depth for free.  Trenches can't do that.

Look online at images of Subtropolis.  If the digging is easy, scaling a tunnel system seems pretty straight forward.
A 20m deep trench is only "deep" relative to narrow tunnel diamiters. A "Waterbed" shaped pressure vessel hundreds of meters on a side and compressed from the top by 10m of regolith is much easier by cut-and-cover than a boring machine.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/28/2019 01:41 pm




Maybe some cargo Starships could be specifically built as hab towers.

Instead of one or two cargo bays the ship would have accommodation rooms on multiple levels
that would be packed full of non bulky cargo for the trip out.  Once landed and unloaded
it becomes an apartment block.

This seems to be reflected in the Flint Kids video. The artists placed a couple of Starships horizontally as "barracks."

As Paul451 says, cut n cover is always preferred over tunnel boring. Elon's Boring Company tunnels are bored because there is street infrastructure overhead. Otherwise, it's simpler to remove overburden and put it back over something solid.

I've already detailed the problems around Martian tunnel boring, but I'll sum them up.

1. Bedrock must be fracture free to have a chance of being airtight. Generally this only occurs 50m down. On Mars, bedrock appears fractured down to 100m. Otherwise a marscrete etc lining is a requirement.
2. Only 5-10m of regolith is required to cut out virtually 100% of radiation.
3. Rock pressure comes in at the sides, not over the top as most people assume. Tunnels are squeezed laterally by the rock on either side.
4. On Earth, every site is unique and delays will be encountered. On Mars, this is even more true.

Sedimentary rocks on Mars are also incredibly porous, which makes them easy to tunnel through but virtually impossible to make airtight without a liner.

https://www.theweek.in/news/sci-tech/2019/02/02/Rover-Curiosity-finds-Mars-rocks-more-porous-than-thought.html

There are valid counter-arguments to these.

A liner is much simpler than a solid tube, since it is not structural - it can be sprayed on, and let it cure inside those crack of porous paths.

If you need to dig until you have 10 m above the top of the tube you want to build inside the trench, that's a very deep trench - not quite "trench and bury".  15 m deep?  20 m?

Tunnels remain horizontal as you dig into a hill side, giving you depth for free.  Trenches can't do that.

Look online at images of Subtropolis.  If the digging is easy, scaling a tunnel system seems pretty straight forward.
A 20m deep trench is only "deep" relative to narrow tunnel diamiters. A "Waterbed" shaped pressure vessel hundreds of meters on a side and compressed from the top by 10m of regolith is much easier by cut-and-cover than a boring machine.

If you "go wide", it starts making more sense.

I'm not sure that's the plan though. Digging 15 m deep (5+10) and 100 wide is a big project though.  And you still need a pressure vessel.

Nice thing about a tunnel is that once you go into a hillside and seal, you're basically pressurized and can grow while already occupying the space.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 03/28/2019 02:05 pm
I'm not sure that leaving Starships as-is would be acceptable habitats, since the main factor for hab design seems to be radiation mitigation, and I don't think that standard Starships would have sufficient shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 03/28/2019 02:41 pm
I'm not sure that leaving Starships as-is would be acceptable habitats, since the main factor for hab design seems to be radiation mitigation, and I don't think that standard Starships would have sufficient shielding.

Would need to cut and cover to add radiation mitigation. Good idea for additional habitats, especially early on during settlement, but not the "Envisioning Amazing Martian Habitats" topic of this thread. Now that SS will be made of stainless steel, later in settlement construction it might be a better idea to scrap old SS for the steel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/28/2019 02:56 pm
A liner is much simpler than a solid tube, since it is not structural - it can be sprayed on, and let it cure inside those crack of porous paths.

Tunnel liners need to be structural, except under rare circumstances.

If you need to dig until you have 10 m above the top of the tube you want to build inside the trench, that's a very deep trench - not quite "trench and bury".  15 m deep?  20 m?

If you dig down 10m, you have 10m of fill. You don't need to return the surface to its previous level after burying the habs.

And again, earthmoving is not the expensive part of building. Whenever you have the choice, you dig from above rather than tunnel, down to fairly significant depths.

Tunnels remain horizontal as you dig into a hill side, giving you depth for free.

"Free".

Nice thing about a tunnel is that once you go into a hillside and seal, you're basically pressurized and can grow while already occupying the space.

The same is true of cut'n'cover. Each section can be sealed, covered and used, with new construction continuing off the ends.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2019 03:23 pm
Twark_Main, thanks for your long and very well-written reply. I'm on my phone so I'll be shorter.

I didn't realise that your hab textile could be made with ISRU. Interesting. I'd like to see more info on basalt fibres and how well they work for big tensile structures.

Thank you, and my sincere apologies for being so long-winded. I too was on the phone believe it or not. :'(

Briefly, basalt fibers date back to the 50s but were classified until 1995. Both terrestrial production cost and specific strength are in between glass fiber and carbon fiber. Basalt fiber reinforced polymer (BFRP) tendons are currently used as pre-stressed rebar because it's lighter (easy installation), non-corroding, and non-spallating. Both creep (https://www.sciencedirect.com/science/article/pii/S0261306914001952) and fatigue (https://www.sciencedirect.com/science/article/abs/pii/S0950061817300880) knockdowns are about 50% of UTS.

Also there's at least one group working on basalt fiber for Mars ISRU applications. See https://seti.org/future-made-mars (https://seti.org/future-made-mars) or https://www.madeofmars.com/presskit (https://www.madeofmars.com/presskit).

Your habs would still need a huge pile of regolith on top, wouldn't they?

Much less huge. :) Roughly 3-5 meters thickness of regolith for long term habitation, or whatever is needed to achieve the building's radiation requirements (eg automated hydroponic buildings might require little shielding). The sides can have lighter shielding due to the geometry of incoming radiation, so maybe hanging sandbags. Large side "ramps" are not necessary for that purpose.

My vision for the first years of a Mars base is that fuel and oxygen production takes place in a turn-key readymade factory installed in a Starship. Another Starship brings tunnelling equipment and a third brings the crew in what will serve as their hab until tunnels are made.

The first crew won't be big enough to set up such heavy equipment imo. That will be done with the next phase (requiring several dozen workers at a minimum, and more landed equipment mass), so likely the first crew of ~10 will be mainly setting up solar panels and establishing the temporary work camp for Phase 2. The experience lamontagne was good enough to relay of bootstrapping a mine in northern Canada (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1631470#msg1631470) is quite instructive I think.

The Phase 2 camp will need water and oxygen recycling equipment, but food would still be almost entirely imported -- imported food has surprisingly good economy (and much lower risk) compared with importing surface-based hydroponic LED greenhouses. To create lots of livable volume quickly for Phase 2, the Phase 1 crew might inflate a large hab or three and cover it with regolith using a truck-mounted multifunction boom crane, or perhaps a regolith "snowblower." I presume the regolith is blasted from a convenient quarry and handled via Mars-Bobcat and Mars-pickup truck (similar to many small local gravel beds on Earth), and/or is waste regolith from water mining.

[sidenote] Alternately pushing regolith on top prior to inflation is another possibility (let the air compressor do the lifting), but that risks driving over the hab. Possibly the "above ground pool" structure on the roof unfolds first, gets filled with regolith, and then inflate the hab? This lowers the necessary crane height, but I would worry about stability during inflation. You need a tall crane anyway to lower heavy future payloads from Starship, so imo use a taller crane and pre-inflation early on, with post-inflation left as a possible future optimization.[/sidenote]

The machinery could be safely teleoperated from workstations inside the landed Starship, with a couple guys drawing straws for EVA duties as needed. Mostly Phase 1 consists of lowering various equipment down from Cargo Starships onto the 'pickup,' driving it to the inflat-a-hab or PV array or water mining site, and finally setting up and testing the equipment. There's simply not yet enough man-power or heavy equipment or power generation landed in Phase 1 to do anything much more elaborate. Imo it's better to "sprint" from <10 people to >100 people before starting the serious ISRU work, which can then proceed that much faster since it's not starved of equipment/power/manpower (whichever's the limiting resource).

What will the larger Phase 2 crew do, aside from support staff? Mostly... sit in that nice shielded hab Phase 1 built teleoperating equipment, drawing straws for needed EVAs. :D
 
(obviously EVAs would be carefully scheduled, but it's fun to imagine)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/28/2019 03:47 pm
A liner is much simpler than a solid tube, since it is not structural - it can be sprayed on, and let it cure inside those crack of porous paths.

Tunnel liners need to be structural, except under rare circumstances.

These are the circumstances.  Why would sealing a deep tunnel's wall require the sealant to be structural?  The bored wall already is.
Quote

If you need to dig until you have 10 m above the top of the tube you want to build inside the trench, that's a very deep trench - not quite "trench and bury".  15 m deep?  20 m?

If you dig down 10m, you have 10m of fill. You don't need to return the surface to its previous level after burying the habs.

Not quite true.  If you just leave the tailing in a large (and by necessity much flatter) mound above what you buried, it's not the same as a compacted and enclosed earthfill, and certainly not the same as an undisturbed layer of soil as in the case of a tunnel.
Quote

And again, earthmoving is not the expensive part of building. Whenever you have the choice, you dig from above rather than tunnel, down to fairly significant depths.

You keep saying that... 
Quote


Tunnels remain horizontal as you dig into a hill side, giving you depth for free.

"Free".

Yes, free.  The tunnel quickly goes deeper without you having to expend more resources to get this depth.
Trenching has to overcome any change in the terrain elevation, and when you're talking about 100s of meters, that's a big deal.
Tunneling uses theses changes instead of fighting them.
Quote

Nice thing about a tunnel is that once you go into a hillside and seal, you're basically pressurized and can grow while already occupying the space.

The same is true of cut'n'cover. Each section can be sealed, covered and used, with new construction continuing off the ends.

Then in that case you're building pressure vessels that during construction need to hold full pressure - more costly than a sealant on bored walls.

The sealant btw can be plastic based, derived essentially from the Methane-at-the-top chemical food chain.  Maybe composited with sand. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2019 05:21 pm
Cut-and-cover is nice, but has unnecessary constraints. Why "cover" with the same material you cut? For that matter why bother "cutting" under the hab at all?

Just grade the site flat (or better yet, select an existing flat site), erect/inflate the hab, and cover it with some regolith you blasted from a convenient quarry nearby. There's no requirement the shielding regolith come from the same site, and drilling+blasting with explosives has far better equivalent system mass than breaking up permafrost with a PV-powered excavator. Flying debris risk is handled by having the proper setback distance and/or selecting the quarry site such that natural topology shields fragile assets.

And yes, there's some cost to transport loose regolith by truck (as a side benefit, the delivery truck can dump it exactly where the handling machinery picks it up, simplifying design and operation). On Earth these transport costs mean we don't source fill or gravel from the other side of the planet, but we also don't typically source it from someone's own property either (farmers being one noteable exception). Having a local, community-scale gravel/fill pit for major construction projects makes sense on Mars for the same reasons it makes sense on Earth.

Even if you get the regolith on-site, dig it up somewhere else. Why move the dirt twice? Just move enough dirt to flatten the hab site, then source the rest wherever it's convenient. I suppose sometimes the most convenient and cheapest source might be "PV excavate the whole building footprint down 10 meters" but my hunch is that's rare.

Naturally those same transport trucks can also remove waste spoil from underground hab excavation sites, water mines, metal mines, etc. If you have such a "free" source you can delete the gravel mine entirely for even lower cost, but before those come online blasting offers a relatively cheap source.

And you only need blasting on the worst-case assumption that no loose material is readily available. Best-case the cheapest regolith source is scooping up the nearest scree cone.

"Scoop-and-cover?"
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/28/2019 05:48 pm
"Cut'n cover always cheaper than tunnelling"

- Well, why has Musk started The Boring Company? - Yup: Specifically to create exponential improvements in tunnelling.

It is not exactly as if he is hiding that ambition. Obviously TBC is intimately connected to his Mars plans.

Cut'n cover may be preferred in many instances on Earth, but when you go to Mars and have to deal with radiation and a near-vacuum it is no longer straightforward.

Cut'n cover means that you invariably need a built structure, because it will only be covered in loose rubble or sand. Importing the building materials for that structure is prohibitive.

The "buildings" are already on Mars. They just need to be hollowed out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 03/28/2019 06:55 pm
Just grade the site flat (or better yet, select an existing flat site), erect/inflate the hab, and cover it with some regolith you blasted from a convenient quarry nearby.
The problem is that it will take a lot more regolith to cover a surface structure than to cover an equivalent volume in a trench. You're essentially building a whole hill rather than a roof.  And it will take a enormous volume of material to provide the same protection as it would for a buried structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 03/28/2019 08:31 pm
Just read the last 2 pages... Particularly MeekGee and Paul451.

Tunnelling vs "cut" and cover. Etc:
On earth most tunnels are for trains, roads etc.... and with diesel we have unlimited energy for vehicles. And with sufficient budget, unlimited vehicles.

On Mars, to make living hab space for 100 people, will not require miles of tunnel.
On Mars extra heavy machines are "expensive" due to "import" costs. So moving lots of regolith is effectively expensive.
Because of the need for solar power fields... energy will be fairly "expensive". Moving mass costs power as well as machinery.
Working relatively slowly at a tunnel will involve moving less mass, so it will use less machines, and IMO less energy. The boring machine/s whether TBM, tunnell-header, and/or conveyors/dumpers will have less overall work than building hills (even 5m hills).

A soft liner buried under lose fill will have to be protected against collapse due to depressurization.
A tunnel in unfractured rock, will be self supporting. Some structure may still be needed, but I agree that mostly it will be lining. The bassalt-fibre sounds exciting... and spray-on concrete, and/or rubber/plastic for sealing... More tec, but less volume, and seemingly less failure points to the final product.

I expect there will be several solutions. Tunnels just seem a good early one - depending on the local geography.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/28/2019 08:49 pm
I hope this table proves useful to the discussion.
It is an adaptation of a few tables I found regarding the Embodied Energy of Materials, a method for evaluating materials for sustainability.  All materials are compared on the basis of MJ of energy per kg of production.

I find it interesting to adapt to Mars because on Mars all energy is provided by either the sun or nuclear, with no other sources.  So I expect embodied energy to track almost perfectly with material cost.  In my case I need to say that i used artificially lit greenhouses, so even agricultural products are linked to the cost of energy.
I have two exceptions. 
-Oxygen, since its value is tied to hydrogen.  In my table I gave all the costs to hydrogen. 
-Products that come from surface algae/plancton bags, as these get their energy directly from the sun, and their main cost is tranportation/fabrication of the bags.

The cost for Compressed Regolith Blocks is speculative, but they do appear to be very cheap if calcium carbonate is available.
I've also joined a more formal paper for reference and for people that want to see sources!

The fourth column is the ratio of transportation cost to production cost.  Showing what is the most economical to produce on Mars.
The table is heavily slanted against plastics, as there are made from hydrogen and hydrogen is very expensive.   

If we added a column for strength vs mass and cost I expect steel would win handily against concrete.  That is why we have steel pressure vessels and not concrete pressure vessels :-).  Steel is also much cheaper than plastics, on Mars. 

The table is also imperfect because it doesn't take into account the mass and cost of production equipment.  However, I have observed that for equipement producing a few thousand tonnes per year, the production equipment mass doesn't seem all that heavy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/28/2019 08:57 pm
As a companion to the materials cost here is how I calculated my energy costs for an entirely solar powered colony.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2019 08:58 pm
Cut'n cover may be preferred in many instances on Earth, but when you go to Mars and have to deal with radiation and a near-vacuum it is no longer straightforward.

Tunneling is great, and there will absolutely be tunneled structures on Mars. But can covered above-ground habs be just as cheap, or cheaper? It's definitely a Hard Problem, but worth a try imo.

Tunnels have huge advantages, but also a few downsides which imo give covered structures a fighting chance. Tunnels are slower to build out, require heavy equipment, need a fundamentally expend energy to fracture rock, and require interior outfitting work similar to a covered hab.

Tunnels are great, and I hope design ideas can cross-pollinate between tunnels and covered habs.

Cut'n cover means that you invariably need a built structure, because it will only be covered in loose rubble or sand. Importing the building materials for that structure is prohibitive.

Tunnelling means that you invariably need a built structure too, unless folks live in empty caves. 

The real difference is the pressure restraint mass, but if used intelligently that tensile pressure restraint can make the interior secondary structures much lighter (see my proposed "tensile floors" and lightweight tensile interior outfittings), possibly enough to offset the mass of the pressure vessel itself. Obviously if this is correct you can flip it around and use the same trick in a tunnel. :) Still, it would shrink the cost delta considerably.

I challenge you to find a tunnel floor system that's lighter. Perhaps each level as its own tunnel? This isn't "free" either. Your thermal losses go through the roof (literally) which can destabilize the surrounding permafrost, so you need more thermal insulation and heating equipment. And the thick rock walls/floors make the hab less dense overall, lengthening utility runs and human circulation patterns.

A covered hab can locate the radiation shield inside the thermally conditioned space (but outside the pressure vessel) so it becomes a thermal asset instead of a liability. If the heater breaks down the warm rad shield can store multiple days of heat, whereas tunnels would immediately start getting colder because of the large thermal envelope area.

Also isn't Mars dust toxic? How far down? Covering every rock wall/floor/ceiling with some suitably durable sealant (not a thin anti-leak film, but closer to thick lead encapsulation paint) and thoroughly decontaminating the inside from all remaining dust sounds like a lot of work. Yet another reason why tunneling isn't quite as cheap as it first looks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2019 09:24 pm
Just grade the site flat (or better yet, select an existing flat site), erect/inflate the hab, and cover it with some regolith you blasted from a convenient quarry nearby.
The problem is that it will take a lot more regolith to cover a surface structure than to cover an equivalent volume in a trench. You're essentially building a whole hill rather than a roof.

Not so. You must still be picturing large earthen (marsen?) ramps going up each side. In reality all you need is a thick roof slab and thinner hanging sandbag walls.

The only thing a covered design loses is the "need" to excavate an underlying trench.

And it will take a enormous volume of material to provide the same protection as it would for a buried structure.

Fortunately there's no need to duplicate the radiation protection of a buried structure, only achieve acceptably low radiation levels. Some buildings like automated hydroponic farms will need very little radiation protection.

Akin's Law #13: Design is based on requirements. There's no justification for designing something one bit "better" than the requirements dictate. https://spacecraft.ssl.umd.edu/akins_laws.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/28/2019 09:55 pm
Cut-and-cover is nice, but has unnecessary constraints. Why "cover" with the same material you cut? For that matter why bother "cutting" under the hab at all?

You are scrapping up regolith (or blasting it, in your suggestion) to cover the hab. Why not use the hole?

There's no requirement the shielding regolith come from the same site

Never said it did. Nor saying it would. It's likely that the cover for any given site would come from the cut removed from the next-plus-one site. You can call the next-plus-one site a "quarry" if it makes you feel nice. And you can call the next site, currently being developed, "the former quarry" too.

and drilling+blasting with explosives has far better equivalent system mass than breaking up permafrost with a PV-powered excavator.

If your primary water source is permafrost, then you'll be doing that anyway.

[And if your primary water-source comes from something else, you might look into that for your habitat. Eg, if you are using Rodriguez wells, maybe your habitat ends up in the wells.]



meekGee,
Re: "Free"
Because you are ignoring the cost and difficulty of building a freakin' tunnel. You aren't getting "depth for free", you're getting depth at greater expense/difficulty/labour/power-use/equipment-wear/etc than just scrapping away some regolith and piling it back on.

Re: Changes in level.
"Doctor! Doctor! It hurts when I do this!"
"So stop doing that."

Re: Liner
Tunnels use structural liners. Typically pre-cast reinforced concrete segments. In addition, you typically litter the tunnel sides with drilled rock anchors to hold everything together.

Interestingly, the liners would be roughly the same as needed to support the overburden in a cut'n'cover.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/28/2019 10:03 pm
"Cut'n cover always cheaper than tunnelling"

Not always. Once you reach a significant depth, tunnelling is typically cheaper. But we don't need depth, just a bit of cover. There may one day be a need to do that, for the same reasons we do it on Earth, for transport through uncooperative geography, but that's some way down the track (no pun intended.)

- Well, why has Musk started The Boring Company?

Musk's savings primarily come from reducing the size of the tunnel. Tunnelling costs are (apparently) nearly linear with volume. If you can halve the diameter, you instantly reduce costs by three-quarters. That's not relevant here, since we're talking habitats, not transport. Short-wide, not long-skinny.

Cut'n cover may be preferred in many instances on Earth, but when you go to Mars and have to deal with radiation and a near-vacuum it is no longer straightforward.

As distinct from everything else? Including tunnelling.

Cut'n cover means that you invariably need a built structure, because it will only be covered in loose rubble or sand.

I'm not sure why everything thinks this is some extraordinary revelation. The material required to support such a load during construction is minor. And once pressurised, non-existent.

Importing the building materials for that structure is prohibitive.

Why would you import material for a compressive structure?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/28/2019 10:20 pm
I think the best method is yet to be determined. I imagine there will have to be a lot of experimentation in the early missions, probably first with a bulldozer.

Apart from habitats they may want to build small embankments to protect things like solar farms from the rocket exhausts during launches and landings. They may also wish to clear the launch/landing sites of large debris.

They will be able to check the feasibility of bulldozing large quantities of regolith in situ in reduced gravity as well as the depth structure and ease of moving regolith in the immediate vicinity. If this works well then I imagine they would just put a hab in any suitable small crater or depression and over fill it.

Much later it may be desirable to experiment with tunnelling. But here’s the bottom line: a bulldozer utility vehicle could have many uses but a tunnelling machine does not and if the tunnelling project fails for whatever reason it’s just scrap.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/29/2019 01:28 am
A new take on the cellular colony.
Each cell is a sphere, partially filled to the level of the connecting circular openings.
HExagonal repeating pattern, with enough left over material for both tension continuity of a pressure vessel, and columnar resistance of a compression member.
The spheres are connected up, then backfilled with 5m + of regolith.
Sadly, the oculus do not let much light in.  I guess this follows the pattern of the original roman Pantheon.

I'm not optimistic, but it seems logical at first glance....
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 03/29/2019 01:41 am
It seems a natural fit to couple cut and cover with processing of ore. Cut>Process>Cover with tailings.  Or perhaps,
Covering could be partially exchanged with using processed materials to create block liners.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/29/2019 04:42 am
A new take on the cellular colony.
Each cell is a sphere, partially filled to the level of the connecting circular openings.
HExagonal repeating pattern, with enough left over material for both tension continuity of a pressure vessel, and columnar resistance of a compression member.
The spheres are connected up, then backfilled with 5m + of regolith.
Sadly, the oculus do not let much light in.  I guess this follows the pattern of the original roman Pantheon.

I'm not optimistic, but it seems logical at first glance....
Looks good to me. Whatever light is lacking could be augmented with modern optics, eg a fresnel lens plus just white paint. Modern malls and other large constructions don't need a huge amount of natural light to be functional. CGI images don't convey the high dynamic range of a human eye well. With lots of white surfaces the apparent brightness would increase dramatically as well.
The oculus might be angled as well so that sunlight enters directly at higher latitudes, and doesn't allow a straight ray path through the thinnest overhead atmospheric column - though reducing skyview helps more for overhead skylights.
As with the previous design, you could intersperse some upright cylinders with domes to provide greater lighting and more view at the cost of shielding. For a feeling of openness, though, you want windows that look out across the landscape.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/29/2019 04:51 am
Also, not specifically habitat related, but deep groundwater might exist on Mars, enabling colonies right at the equator and drastically reducing the amount of extraction effort. Harder to drill, but once the water starts flowing no further extraction effort is needed

https://phys.org/news/2019-03-evidence-deep-groundwater-mars.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: Florent D on 03/29/2019 07:26 am
I don't know if you know this study of the Mars Society (France) on future Martian habitats:
http://planete-mars.com/martian-habitats-molehills-or-glass-houses/ (http://planete-mars.com/martian-habitats-molehills-or-glass-houses/)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/29/2019 12:47 pm
Cut-and-cover is nice, but has unnecessary constraints. Why "cover" with the same material you cut? For that matter why bother "cutting" under the hab at all?

You are scrapping up regolith (or blasting it, in your suggestion) to cover the hab. Why not use the hole?

Except you are using the hole — it's an active mine site! Why don't people on Earth build houses directly on top of active surface mines? Same reasons on Mars. :)

The constraint of shaping your hole to fit the hab shape (or backfilling enough volume if the hole has sloped walls) introduces unnecessary work. On a real mine you just remove the material on-demand from wherever it's most convenient/safe.

One should put a hab in a good location for building a hab, and dig up dirt in a good location for digging up dirt. These aren't necessarily (or often, in fact) the same location. Seems logical enough, no?

Your question also assumes that the quarry site begins flat, such that removing material produces a hole. Many gravel mines are dug out of the sides of hills. If you scoop material from a convenient scree pile you're just "flattening a hill" rather than digging a proper hole.

There's no requirement the shielding regolith come from the same site

Never said it did. Nor saying it would. It's likely that the cover for any given site would come from the cut removed from the next-plus-one site. You can call the next-plus-one site a "quarry" if it makes you feel nice. And you can call the next site, currently being developed, "the former quarry" too.

Clarification: I used the word "quarry" because I meant exactly that. What you've described is not a quarry. ;)

If that turns out to be the cheapest source of regolith, great! But I doubt that will be the typical case, and here's why.

If you source your material from a future construction site, your hole now needs a flat bottom (or whatever shape your hab is) so you can't just use blasting. Now you need heavy PV powered equipment to excavate and grade a neat, finished hole. That's an unnecessary expense compared to just plopping a hab down on a pre-existing flat plain (which you need/want anyway for landing Starship) and cheaply blasting dirt from somewhere else that you "don't care about."

And again, most likely there's no need to blast. So the real comparison is between "excavate a neat rectangular hole with a PV excavator etc" and "scoop dirt from the pile and truck it a couple miles." Looking at costs here on Earth the latter is substantially cheaper per tonne of dirt (why is that?), but obviously for Mars the costs remain to be seen. But it's strange to me that you expect those two costs will "flip around" on Mars without any justification given.

and drilling+blasting with explosives has far better equivalent system mass than breaking up permafrost with a PV-powered excavator.

If your primary water source is permafrost, then you'll be doing that anyway.

This is an argument in favor of covered habs. Like I said, waste dirt from baking permafrost would provide an excellent "free" source of loose material, and if it's available you can delete the gravel mine entirely (or partially) and lower the cost of covering habs.

Also this is incorrect. For water mining you don't need to break up the permafrost using a PV excavator. Instead you can fracture it with explosives and pick it up as loose rubble. The tiny explosive residue is nothing compared to all the toxic nasties already present in Mars water.

Recall that here on Earth we literally break up and cart away entire mountains because recent automation (along with Nobel's Blasting Powder™ and its descendants) makes it cheaper than "just" tunneling down to the coal.

[And if your primary water-source comes from something else, you might look into that for your habitat. Eg, if you are using Rodriguez wells, maybe your habitat ends up in the wells.]

I saw that suggestion a while back, but I don't think the scaling works. Napkin math says you need far more pressurized volume than it can reasonably provide, since the rate of expansion is even slower than tunneling.

Also it splits the baby. A hybrid mash-up Rodriguez-well-plus-hab is unlikely to be a good hab or a good Rodriguez well as compared with separately designed and optimized versions of each. It's not definitive, but it should caution us that "here there be [design] dragons."

Interestingly, the liners would be roughly the same as needed to support the overburden in a cut'n'cover.

Yes quite interesting! How do you figure?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 03/29/2019 01:00 pm
Not so. You must still be picturing large earthen (marsen?) ramps going up each side. In reality all you need is a thick roof slab and thinner hanging sandbag walls.
But a slab is no longer just a pile of loose regolith, but a manufactured item (from marscrete I presume?), which requires a whole other level of industrial capabilities.  Piling dirt with a front-end loader is one thing, but generating cement is another.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/29/2019 01:55 pm
so you can't just use blasting.

Nor would I. Using explosives to make gravel was your thing, not mine.

So the real comparison is between "excavate a neat rectangular hole with a PV excavator etc" and "scoop dirt from the pile and truck it a couple miles." Looking at costs here on Earth the latter is substantially cheaper per tonne of dirt

I never said anything about a "rectangular hole". I'm assuming loose dug, for precisely the reason as your last sentence, on Earth it is cheaper. Certainly cheaper than your quarry. Certainly cheaper than manufacturing a marscrete slab of the same thickness.

Why don't people on Earth build houses directly on top of active surface mines?

Building on the surface is usually cheaper. However, when you already have the holes, there's no trees and it's 500 miles to civilisation...

(https://www.cooberpedy.sa.gov.au/webdata/resources/photogallery/District%20Council%20Web%20Images%20Stock%202014-15%20(Large).jpg) (https://www.cooberpedy.sa.gov.au/webdata/resources/photogallery/District%20Council%20Web%20Images%20Stock%202014-15%20(Large).jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/29/2019 02:05 pm
@Tulse: Oops, my apologies for the poor terminology. By "slab" I meant slab-shaped, not rigid. It would still use uncompressed regolith.


A new take on the cellular colony.
Each cell is a sphere, partially filled to the level of the connecting circular openings.
HExagonal repeating pattern, with enough left over material for both tension continuity of a pressure vessel, and columnar resistance of a compression member.
The spheres are connected up, then backfilled with 5m + of regolith.
Sadly, the oculus do not let much light in.  I guess this follows the pattern of the original roman Pantheon.

I'm not optimistic, but it seems logical at first glance....

I love it! An excellent work, thank you. Of course I'm sure you can already guess what my suggestions will be... :D

The columns imo shouldn't taper quite so dramatically. The thinnest section defines the weak link, so the column should be more-or-less the same thickness top to bottom, optimally thickening near the top and bottom to handle the stress concentration (or more typically in modern construction, cross-braced). And if you rearrange that same column material into an I-beam it will provide more bending stiffness.

I agree with Lampyridae that the oculus lighting isn't as bad as it looks (I would look into the opinion of non-photographers who visit the Pantheon, assuming you can still find anyone not constantly taking cell phone pictures :D). But what happens if you put a thin optical diffuser at the bottom of the oculus tube?

Though I suppose at that point, what's the advantage over an LED panel? Seems like a waste of pressure glass (and heat loss, and decompression risk, and inspection/maintenance, and radiation admittance). Best imo to put the costly pressure windows onto scenic towers and outlooks, where the glass-to-enjoyment ratio is much better.

I envision that small outlook "lounges" might be located at each corner of a rectangular hab, allowing full situational awareness and opportunities for socialization while keeping radiation levels low in the regular hab space. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 03/29/2019 02:27 pm
Oops, my apologies for the poor terminology. By "slab" I meant slab-shaped, not rigid. It would still use uncompressed regolith.
But if it is uncompressed and has no cementing agent, what keeps it slab-shaped?  And how does it support its own weight?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/29/2019 07:25 pm
@Tulse: gravity keeps it slab-shaped, and the hab beneath supports its weight.

Reminder: holding up the heavy regolith shield is not the biggest problem structurally speaking, restraining the internal pressure is. Tunneling is the most obvious solution, but my goal is to find out if any other solutions are feasible.

so you can't just use blasting.

Nor would I. Using explosives to make gravel was your thing, not mine.

This is my fault. To be profoundly misunderstood despite my (long-winded and no doubt tedious to read) efforts clearly means I'm doing it all wrong. Apologies to Paul451 et. al. for my deficient communication.

1. It's not that blasting is "my thing," it's simply the objectively cheapest way to move earth (and yes I know, Mars is different). A shockingly tiny amount of (at first imported!) explosives can move an enormous amount of material, by a factor of millions of times. Briefly, blasting is so efficient because the shock wave automatically "calculates" the weakest cut planes so it optimized fracture energy, and cost-wise explosives are sorta like a bulldozer minus everything but the gas tank (yes I know no gas on Mars, but hopefully my point is understood). Why do you think dynamite was such a transformative invention?  In short blasting is a huge mass/cost leverage arm, and anyone who rejects it out-of-hand is leaving a powerful tool on the table.

2. You probably don't even need to blast. Blasting is only the worst-case-scenario if there's no other cheaper source of loose regolith (just scoop it up easier/cheaper than blasting) or other bulk shielding material (tunnel spoil, etc). So if you're like me and imagine that tunnels will exist on Mars, then no blasting is needed! :)

3. You don't need to screen the regolith into gravel size. You probably don't want big chunks in the first meter or two (to avoid damaging the hab roof), but beyond that height you can just pile on rubble. Void spaces or density irregularities can be addressed by using a rad meter underneath to "say when" there's enough shielding mass on top.

So the real comparison is between "excavate a neat rectangular hole with a PV excavator etc" and "scoop dirt from the pile and truck it a couple miles." Looking at costs here on Earth the latter is substantially cheaper per tonne of dirt

I never said anything about a "rectangular hole". I'm assuming loose dug, for precisely the reason as your last sentence, on Earth it is cheaper.

I mentioned (and argued against) that alternative in an earlier sentence, but I didn't want to waste our readers' time repeating it. Mea culpa...

As I said, now you have the unnecessary cost of backfilling the sloping volume (equivalent in volume to building that aforementioned huge gravity pile ramp around all sides of an above-ground hab). For small-to-medium size structures this is a big and needless cost, involving moving comparable amounts of material to making the slab-shaped-unconsolidated-pile roof shield.

And you still need a neat flat bottom on your hole. Hab designs seem to scale better as they get wider and longer, so to the first approximation this "solution" solves none of the excavation problems. You still need to expend equipment and energy making a flat graded non-fractured-to-blazes floor for the hole, and that ain't cheap.

Certainly cheaper than your quarry.

I disagree,  but even if you're right, so what? After all car factories are more expensive than cars.

Again an elaborate and expensive quarry is not needed. I can never be quite sure what you're picturing exactly, but I take it you've never been to a small local rural gravel pit? It's not much to look at.

Certainly cheaper than manufacturing a marscrete slab of the same thickness.

Agreed, that's why my design calls for unconsolidated regolith or some other discarded rubble/spoil. I can't think of a cheaper bulk material to use for radiation shielding (again, apart from the obvious tunneling solution).

Why don't people on Earth build houses directly on top of active surface mines?

Building on the surface is usually cheaper. However, when you already have the holes, there's no trees and it's 500 miles to civilisation...

(https://www.cooberpedy.sa.gov.au/webdata/resources/photogallery/District%20Council%20Web%20Images%20Stock%202014-15%20(Large).jpg) (https://www.cooberpedy.sa.gov.au/webdata/resources/photogallery/District%20Council%20Web%20Images%20Stock%202014-15%20(Large).jpg)

Bad analogy.

Coober Pedy houses were built underground mostly because the average ground temperature there is comfortable for human habitation, which eliminates air conditioning and most thermal insulation. This advantage does not apply on Mars, and in fact this is a downside of underground habs on Mars.

Let's be consistent in the type of "hole" we're talking about. Coober Pedy dwellings were either dug out especially for the purpose of habitation, or reused underground mines, not covered surface mining sites.

Anyway the purpose of my rhetorical question is getting totally lost here, so let me simply walk through it. My question was why people don't build houses on active surface mining sites? I'm not asking the legal reason (which is "the mine owner owns it"), but in practical terms why isn't this done? It's not very difficult to come up with pragmatic reasons (like "my house would get blown up in the next blast"), but why are they still blasting? Why doesn't the mine owner sell you the land for your house? Clearly it's because the mine continues to be more economically valuable as a mine than as a "free" basement for your future house. But why is that? And why does this remain true not only for rare things like copper (for which the snappy answer is "because there's still copper left"), but also for plentiful deposits like gravel and clean fill? Why is the hypothetical personal gravel mine on your property likely to be the last place you build a building, not the first?

That's the question I really want to see Paul451 answer, because hopefully then they'll see why "my" quarries are not just pragmatic and profitable, but why they exist in practically every developed locality on Earth. I see no good reason why Mars will be any different.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/29/2019 09:11 pm
I don't know if you know this study of the Mars Society (France) on future Martian habitats:
http://planete-mars.com/martian-habitats-molehills-or-glass-houses/ (http://planete-mars.com/martian-habitats-molehills-or-glass-houses/)
Great reference, thanks!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/29/2019 09:29 pm

Anyway the purpose of my rhetorical question is getting totally lost here, so let me simply walk through it. My question was why people don't build houses on active surface mining sites? I'm not asking the legal reason (which is "the mine owner owns it"), but in practical terms why isn't this done? It's not very difficult to come up with pragmatic reasons (like "my house would get blown up in the next blast"), but why are they still blasting? Why doesn't the mine owner sell you the land for your house? Clearly it's because the mine continues to be more economically valuable as a mine than as a "free" basement for your future house. But why is that? And why does this remain true not only for rare things like copper (for which the snappy answer is "because there's still copper left"), but also for plentiful deposits like gravel and clean fill? Why is the hypothetical personal gravel mine on your property likely to be the last place you build a building, not the first?

Mines sites are dusty and polluted, very bad place for houses.
Mines are also extremely noisy.   And today, usually quite large.  So the hole, even for a mid sized gravel pit, is more suited for a very large stadium rather than a house.
Plus mines are in poor locations.  Mines in very good locations don't get mined  :-)  as the land is more valuable for other reasons.  Mining is a large but not very value added industry.

Explosives are rocket fuel.  Just not very good fuel and very very cheap, here on Earth.  Nitrogen based mostly.  All of this is very expensive on Mars, there are better uses for the nitrogen.  Plus explosives are consumables, while a digging machine eventually produces more volume of rock mined per tonne of transported mass.  Basically explosives break rock, and that uses energy.  Breaking rock in any other way uses the same energy.  Quite often, digging machines will produce much smaller rock, eventually a boring machine really produces sand.  So it uses more energy, to create all those breaks, than explosive that create large boulders, removed by shovels and trucks.

There are interesting possibilities using methane lances combined with machines for rapid precision digging.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/29/2019 09:32 pm
For habitats on Mars I think it is highly undesirable that their structural integrity would be dependent on pressurization. Musk has said that he doesn't want Starships that only maintain their physical integrity when pressurized.

You may need to deal with depressurization emergencies on Mars. As you don you pressure suit to deal with such problems you don't want the ceilings and walls of your habitat to cave in at the same time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/29/2019 09:37 pm
There are as many mining methods as there are mines, but for most mines much of the surface is 'overburden', useless mass that needs to be removed to get to the good stuff.  Once the oveburden is gone, the mine is no longer attractive as a living spot.

Water and gravity have done a good job of leaching away many surface minerals.  So digging is required.  Mars may be different, but the wind has blown around a lot of boring sand.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/29/2019 09:43 pm
For habitats on Mars I think it is highly undesirable that their structural integrity would be dependent on pressurization. Musk has said that he doesn't want Starships that only maintain their physical integrity when pressurized.

You may need to deal with depressurization emergencies on Mars. As you don you pressure suit to deal with such problems you don't want the ceilings and walls of your habitat to cave in at the same time.
Fire happen, for example.  Structures get old.  Contractors do a bad job, exceptionally ;-)
One great example that happened to a colleague of mine:  A contractor piled up soil from a foundation on a nice flat piece of land near his hole.  Unknown to him, there was a four story parking garage bellow.
Eventually the great pile caved in the roof, that pankaked down all four floors...

There are great pictures of collapsed pressures sport areas a few pages back  :-)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/29/2019 09:48 pm
A liner is much simpler than a solid tube, since it is not structural - it can be sprayed on, and let it cure inside those crack of porous paths.

Tunnel liners need to be structural, except under rare circumstances.

There are lots of bare rock tunnels all over the world, many of them without even a coat of paint.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/29/2019 09:52 pm
Musk's savings primarily come from reducing the size of the tunnel. Tunnelling costs are (apparently) nearly linear with volume. If you can halve the diameter, you instantly reduce costs by three-quarters. That's not relevant here, since we're talking habitats, not transport. Short-wide, not long-skinny.

I don't believe that is representative of TBC's work. They want to make tunnel-digging exponentially faster and cheaper.


Cut'n cover may be preferred in many instances on Earth, but when you go to Mars and have to deal with radiation and a near-vacuum it is no longer straightforward.

As distinct from everything else? Including tunnelling.

Surely a cut'n cover structure presents more issues when it comes to radiation and making it air-tight than a tunnel. The tunnel just needs to be plugged at one end.


Importing the building materials for that structure is prohibitive.

Why would you import material for a compressive structure?

I say that importing materials for cut'n cover is prohibitive because I imagine that the cover would rest on some kind of roof made of an imported material. After you make the cut you intend to insert a habitat of sorts and then pile rubble on it. Where does the material for the hab come from? 

Briefly, basalt fibers date back to the 50s but were classified until 1995. Both terrestrial production cost and specific strength are in between glass fiber and carbon fiber. Basalt fiber reinforced polymer (BFRP) tendons are currently used as pre-stressed rebar because it's lighter (easy installation), non-corroding, and non-spallating. Both creep (https://www.sciencedirect.com/science/article/pii/S0261306914001952) and fatigue (https://www.sciencedirect.com/science/article/abs/pii/S0950061817300880) knockdowns are about 50% of UTS.

Also there's at least one group working on basalt fiber for Mars ISRU applications. See https://seti.org/future-made-mars (https://seti.org/future-made-mars) or https://www.madeofmars.com/presskit (https://www.madeofmars.com/presskit).

Thank you, very interesting information. It is not clear to me, however, which percentage of the product can be supplied via ISRU. did I miss that part? For such a material to be really relevant it should be close to 100% ISRU sourced.

Cut'n cover means that you invariably need a built structure, because it will only be covered in loose rubble or sand. Importing the building materials for that structure is prohibitive.

Tunnelling means that you invariably need a built structure too, unless folks live in empty caves.

Tunnels only need furnishings, unlike all the other solutions that need furnishings AND structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/29/2019 11:13 pm
Anyway the purpose of my rhetorical question is getting totally lost here, so let me simply walk through it. My question was why people don't build houses on active surface mining sites?

You're getting fixated on the idea of it being a "mine". It's just scraping up some regolith to cover a fairly small thing. It's not a quarry. Not a mine. No explosives required. No pollution. Dusty, sure, but hey Mars, what else is there. It's basically digging a basement in one yard and throwing the dirt over the fence onto the roof of the house just finished next door.

If you need an actual "mine", it would be somewhere over there where the target ore is. Not over here where the habitat is. But there's no reason why scraping up some of the regolith (overburden, for example) over at the mine site is going to be more suitable than the material where you are preparing to put the next-plus-one habitat. Digging regolith from a spoil heap is not going to be less energy intensive than digging it anywhere else. And there's no reason to assume that the tailings, slime, slag or other waste from mineral processing will a) be more suitable for covering habitats than regolith, b) come out at the rate just as you need it (to avoid piling it up somewhere and then having to scrape it up and move it.)

[As for Earthly analogies: In residential construction, I'm not aware of any fill we bought that was imported from a mine-site. It just came from cuttings of other construction in the city; hell, usually the same suburb. And obviously, if at all possible, you'd use cut from levelling other parts of the same site. I realise that might be different from large projects like major highways, rail beds, etc, but on the scale of habitats....]
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/30/2019 12:09 am
Anyway the purpose of my rhetorical question is getting totally lost here, so let me simply walk through it. My question was why people don't build houses on active surface mining sites?

You're getting fixated on the idea of it being a "mine". It's just scraping up some regolith to cover a fairly small thing. It's not a quarry. Not a mine. No explosives required. No pollution. Dusty, sure, but hey Mars, what else is there. It's basically digging a basement in one yard and throwing the dirt over the fence onto the roof of the house just finished next door.

If you need an actual "mine", it would be somewhere over there where the target ore is. Not over here where the habitat is. But there's no reason why scraping up some of the regolith (overburden, for example) over at the mine site is going to be more suitable than the material where you are preparing to put the next-plus-one habitat. Digging regolith from a spoil heap is not going to be less energy intensive than digging it anywhere else. And there's no reason to assume that the tailings, slime, slag or other waste from mineral processing will a) be more suitable for covering habitats than regolith, b) come out at the rate just as you need it (to avoid piling it up somewhere and then having to scrape it up and move it.)

[As for Earthly analogies: In residential construction, I'm not aware of any fill we bought that was imported from a mine-site. It just came from cuttings of other construction in the city; hell, usually the same suburb. And obviously, if at all possible, you'd use cut from levelling other parts of the same site. I realise that might be different from large projects like major highways, rail beds, etc, but on the scale of habitats....]
Mine site fill is often contaminated with chemicals, such as nitrates from the explosives, various sulfur compounds, and other stuff coming from the freshly ground rock.  Breaking the rock frees all kinds of stuff, some of it unpleasant even in small concentrations
For highways, much of the engineering work is determining how to spread out the fill from mountains into valleys to reduce overall transportation.  At least in regions with hills :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/30/2019 12:17 am
Musk's savings primarily come from reducing the size of the tunnel. Tunnelling costs are (apparently) nearly linear with volume. If you can halve the diameter, you instantly reduce costs by three-quarters. That's not relevant here, since we're talking habitats, not transport. Short-wide, not long-skinny.
I don't believe that is representative of TBC's work. They want to make tunnel-digging exponentially faster and cheaper.

They hope to develop a method of adding rock anchors and structural lining to a tunnel continuously as the TBM cuts. Currently you stop/start between tasks, meaning the TBM-proper is sitting unused most of the time. Since you don't believe structural liners are needed, it's not relevant to your argument.

(I believe they also want to sinter some of the waste directly into liners. And presumably want a way to do maintenance continuously, such as replacing cutting disks without stopping the TBM-head and pulling away from the work-face. Right now, however, I don't believe they've done any of that anyway, what they have is smaller diameter tunnels. Their main party trick is to change the way you use tunnels; instead of allowing cars to drive themselves, you use automated electric sleds to carry the cars. Smaller lanes, single lane, faster speeds (in theory), and reduced risk of fire (again, in theory).)

The tunnel just needs to be plugged at one end.

If I'm picturing what you are describing correctly, where do the cuttings go?

There's a whole back-end supporting the actual work-face that goes all the way out of the tunnel. You can't use the tunnel while it's still being dug (well, I mean, you do, but only for tunnelling support operations.) You certainly can't seal it off.

If you want to use the tunnel as you go, you'd need a minimum of two tunnels, two cutting faces (I'm avoiding saying "TBMs" because you wouldn't literally use TBMs. Wrong tool for the job.) With your main waste removal and access to the outside down one tunnel, the other branching into it via a side cutting. You then seal off the entrance to the second tunnel, and build your pressurised habitat up to the side-cutting. As the two tunnels lengthen, you periodically excavate another side-cutting, re-jigger the waste feed to that point, then extend a new section of pressurised habitat in the second tunnel between the two side-cuttings, old and new, in that tunnel; the first tunnel remains solely the operations side.

Alternatively, two tunnels (or one larger, split for use) in to the cliff/mesa/crater-wall/whatever to a point where you make a large node. Then branch tunnelling operations from that node in a star pattern. As each arm is finished, you remove the tunnelling systems back to the node (and do whatever you need to pressurise that arm) and start a new arm from the node. Once you've done a full star - four, five, six, eight-arms, however many - you double up (or widen) the last arm and turn the end into a new node. Then build a new star. Rinse/repeat.

Tunnel liners need to be structural, except under rare circumstances.
There are lots of bare rock tunnels all over the world, many of them without even a coat of paint.

"Except under rare circumstances". It's limited to very high quality bedrock. If you are dealing with weak, fractured rocks, you need liners. And that's what most sites on Mars will be, particularly because of cratering.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/30/2019 12:39 am
Another cellular structure, closer to what Twark Main as been proposing.
Inspiration is the Cordoba Mezquita, one of my favorite building in the world.

The cells could vary in size, and eventually create much larger spaces.
I think it's a good compromise between a pressure vessel and a compression structure.  And as it would be steel on Mars, if could have some really light columns/vertical tension members.
I expect the dome would be a double wall, with a structural interior and a ribbed vault holding multilayer insulation,, with an outer covering preventing the insulation from being crushed.
Safety walls can be set more or less arbitrarily as needs require.
The outer walls/cells could be domes and transparent tubular sections.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/30/2019 12:57 am
More of the same.

In a way it's just a steel frame building with a number of domed roofs, that doesn't need to worry about water pooling in the joints.  Plus a weird inverted domed structural steel floor.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/30/2019 07:16 am

Mines sites are dusty and polluted, very bad place for houses.
Mines are also extremely noisy.   And today, usually quite large.  So the hole, even for a mid sized gravel pit, is more suited for a very large stadium rather than a house.
Plus mines are in poor locations.  Mines in very good locations don't get mined  :-)  as the land is more valuable for other reasons.  Mining is a large but not very value added industry.

Couldn't have said it better myself.

Though from a certain point of view, mining is the only value added industry. The origin of the English word "mine" (to dig out ore from the Earth) is the English word "mine" (a declaration of ownership). Mining is essentially how we turn planets into private property. :D

Just to be clear this isn't to say anything bad about private property, I just think it's an interesting perspective shift. No off-topic flame wars.

Plus explosives are consumables, while a digging machine eventually produces more volume of rock mined per tonne of transported mass.

Does the math work on this though? After all, digging machines don't last forever, and require a continuous supply of replacement consumables (teeth, spare parts, etc). Some things will be manually repairable with a welding machine, but human labor is expensive, and an AI-powered "fix anything that breaks" bot is a while off, probably requiring AGI.

Of course explosives might later be manufactured on Mars as sufficient demand develops.

  Basically explosives break rock, and that uses energy.  Breaking rock in any other way uses the same energy.  Quite often, digging machines will produce much smaller rock, eventually a boring machine really produces sand.  So it uses more energy, to create all those breaks, than explosive that create large boulders, removed by shovels and trucks.

Precisely. Using loose rubble for some of the shielding mass reduces its total embodied energy requirements.

There are interesting possibilities using methane lances combined with machines for rapid precision digging.

True. The embodied energy will be correspondingly greater than a hypothetical "methalox blasting" (is that a thing?), but the trade-off is you get much more precision. How does the energy and consumable mass compare with a regular diamond saw? And how efficient is the manufacture of actual explosives on Mars vs. the best-case thought experiment of using straight methalox?


For habitats on Mars I think it is highly undesirable that their structural integrity would be dependent on pressurization. Musk has said that he doesn't want Starships that only maintain their physical integrity when pressurized.

You may need to deal with depressurization emergencies on Mars. As you don you pressure suit to deal with such problems you don't want the ceilings and walls of your habitat to cave in at the same time.

As mentioned in my inaugural post, I agree. But the desirability (and the design penalty you should 'rationally' be willing to pay) gets smaller the more reliable the pressure maintainance gets. Leak-before-burst is common, so pressure monitoring gives you early warning. And a large hab takes a long time to depressurize, so you can slap a super sticky repair kit on it. If it's quick to depressurize, you're dead anyway. So I'm not totally convinced that this so-called-requirement is actually a necessity.

Not sure about the Starship analogy. Starship can only maintain its physical integrity during flight when pressurized, so clearly Musk doesn't consider this a hard-and-fast rule. Afaik the only reason Musk did that is for ease of handling in the factory so it doesn't wrinkle the metal, but the process of manufacturing an inflatable pressure vessel has no such issue from accidentally handling unpressurized components. These inflatable habs are initially built on Earth of course.

My favored solution is just installing columns at the perimeter (outside the pressure vessel) and using a "3D suspension bridge" to hold up the rad shield. The cables would go through the regolith so they probably need a protective jacket, but that's not so heavy. Guy wires and rock anchors would handle side loads. These columns might be made from imported stacked CFRP cones, marsteel tubes, tensile wrapped marscrete, interlocking compressed regolith block, or some other suitable material.

For a rigid cellular hab I think you probably just make the grid of vertical steel columns do double-duty as both tensile "cables" when pressurized and compressive columns when unpressurized. Also each column needs a marscrete footer to transfer weight to the ground. The whole hab can float off the ground and achieve very small thermal transfer, which is a Good Thing™ for not melting the underlying permafrost.


There are as many mining methods as there are mines, but for most mines much of the surface is 'overburden', useless mass that needs to be removed to get to the good stuff.  Once the oveburden is gone, the mine is no longer attractive as a living spot.

Yep, I derailed the conversation by bringing up copper mines. I only mentioned it in passing in order to clarify that this line of reasoning is not what I'm referring to.

Water and gravity have done a good job of leaching away many surface minerals.  So digging is required.  Mars may be different, but the wind has blown around a lot of boring sand.

Yes, thank you. No blasting is required for a boring regolith shield. Just front-end load a naturally occurring regolith sand pile into a truck.

Fire happen, for example.  Structures get old.  Contractors do a bad job, exceptionally ;-)
One great example that happened to a colleague of mine:  A contractor piled up soil from a foundation on a nice flat piece of land near his hole.  Unknown to him, there was a four story parking garage bellow.
Eventually the great pile caved in the roof, that pankaked down all four floors...

There are great pictures of collapsed pressures sport areas a few pages back  :-)

And this perfectly illustrates why this is not a show-stopping problem. :)

Buildings sometimes (but not often) collapse on Earth. Buildings will sometimes (but not often) fail on Mars. People sometimes die in these accidents on Earth. People will sometimes die in these accidents on Mars. On Earth we investigate serious structural failures to determine the root cause, making improvements and enacting oversight to avoid similar things happening in the future. On Mars... well, you get the idea.


There are lots of bare rock tunnels all over the world, many of them without even a coat of paint.

How many of those are located in places where the average ground temperature is -50 degrees Celsius (-58 degrees Fahrenheit)? Of those, how many are inhabited as-is?


Musk's savings primarily come from reducing the size of the tunnel. Tunnelling costs are (apparently) nearly linear with volume. If you can halve the diameter, you instantly reduce costs by three-quarters. That's not relevant here, since we're talking habitats, not transport. Short-wide, not long-skinny.

I don't believe that is representative of TBC's work. They want to make tunnel-digging exponentially faster and cheaper.

Nitpick: there's nothing particularly "exponential" about that. Here it's just a synonym for "a lot."

TBC wants to boost power/thermal by ~3x, dig 100% of the time instead of 50% by installing the liner simultaneously, and make the tunnels 4x smaller in cross-sectional area. That's a 24x improvement in per-km speed, but only a 6x improvement in volumetric production rate. Other TBC cost improvements include near-complete automation, replacing lain HV cables with battery railcars, and adding another rail lane for two-way traffic.

Thank you, very interesting information. It is not clear to me, however, which percentage of the product can be supplied via ISRU. did I miss that part? For such a material to be really relevant it should be close to 100% ISRU sourced.

It can be 100% made on Mars. The fibers are just Martian basalt rock melted and extruded. The resin can be any suitable Mars-derived plastic. The Sabatier process produces a bunch of ethylene as a byproduct, so possibly that. The material cost spreadsheet assumes that plastic is made via inefficient photosynthesis, but direct chemical synthesis is cheaper afaik.

Cut'n cover means that you invariably need a built structure, because it will only be covered in loose rubble or sand. Importing the building materials for that structure is prohibitive.

Tunnelling means that you invariably need a built structure too, unless folks live in empty caves.

Tunnels only need furnishings, unlike all the other solutions that need furnishings AND structure.

Again I think thermal loss and permafrost melt considerations mean your underground hab really wants to be multiple levels. The surface-area-to-volume ratio is just way too high otherwise.

So far the Mars tunnel needs thick insulation, thick toxin-encapsulating paint, and maybe internal structural floors. They're getting more "built" all the time.


You're getting fixated on the idea of it being a "mine". It's just scraping up some regolith to cover a fairly small thing. It's not a quarry. Not a mine. No explosives required. No pollution. Dusty, sure, but hey Mars, what else is there. It's basically digging a basement in one yard and throwing the dirt over the fence onto the roof of the house just finished next door.

If you need an actual "mine", it would be somewhere over there where the target ore is. Not over here where the habitat is.

I didn't hold those preconceptions. Clearly the word "mine" is only a distraction.

Repeat after me: load naturally occurring sand pile into a truck. That's it.

We don't build houses on sand for obvious reasons. And a 100 meter tall gravity pile sand dune holds a lot of sand. So just erect your habs on a naturally occurring hard-packed flat plain (no excavation required. yay, we just eliminated a step!) and truck in the dirt.

But there's no reason why scraping up some of the regolith (overburden, for example) over at the mine site is going to be more suitable than the material where you are preparing to put the next-plus-one habitat. Digging regolith from a spoil heap is not going to be less energy intensive than digging it anywhere else.

Sure it is, because hard ground is needed beneath the hab or else it's unstable. Cue the Monty Python "sank into the swamp" reference...

https://www.youtube.com/watch?v=aNaXdLWt17A (https://www.youtube.com/watch?v=aNaXdLWt17A)

And there's no reason to assume that the tailings, slime, slag or other waste from mineral processing will a) be more suitable for covering habitats than regolith,

I agree, and I am not assuming that. As I said you just use whatever material is cheapest and most convenient. That consideration dominates the selection criteria.

Also, "more suitable" for radiation shielding? All you need is mass! Yes I know about atomic numbers, but between those Mars rocks it doesn't vary that much. If a rock has a slightly higher Z you detect that with the rad meter during shield installation and pile on slightly more thickness.

b) come out at the rate just as you need it (to avoid piling it up somewhere and then having to scrape it up and move it.)

Wait, what's wrong with piles again? They're a great way to buffer huge amounts of loose material, practically for free.

Regarding "having to scrape it up and move it somewhere," the real-world solution is... don't start a pile there. :) Plan ahead. Place your pile somewhere it won't encroach on anything else important, including future build sites. Site Management 101.

It's the old rule of 10: it's 10 times more costly to fix a mistake at each phase. So a mistake that cost $10,000 to fix in planning will cost $100,000 to fix in engineering, and $1,000,000 to fix in production.

[As for Earthly analogies: In residential construction, I'm not aware of any fill we bought that was imported from a mine-site. It just came from cuttings of other construction in the city; hell, usually the same suburb. And obviously, if at all possible, you'd use cut from levelling other parts of the same site. I realise that might be different from large projects like major highways, rail beds, etc, but on the scale of habitats....]

Exactly what I'm saying. Use whatever's most convenient/cheapest.

Residential construction generally requires clean fill only, so mine waste is out. But on Mars "mine waste" could be as simple as dehydrated regolith from the water extracting permafrost oven.



Mine site fill is often contaminated with chemicals, such as nitrates from the explosives, various sulfur compounds, and other stuff coming from the freshly ground rock.  Breaking the rock frees all kinds of stuff, some of it unpleasant even in small concentrations

The mass of the residual explosives is negligible, no?

You're mainly talking about acid mine drainage (https://en.wikipedia.org/wiki/Acid_mine_drainage) aka acid rock drainage. That's caused by sulfur-eating bacteria solubilizing elemental sulfur that's been newly exposed to the air. This forms sulfuric acid which dissolves heavy metals in the runoff.

On Mars there's no sulfur-eating bacteria or air or rain, so no acid rock drainage.

For highways, much of the engineering work is determining how to spread out the fill from mountains into valleys to reduce overall transportation.  At least in regions with hills :-)

Exactly. Whatever's most convenient.



@lamontagne Absolutely splendidly awesome renderings, and I regret not seeing your works prior to finishing this post. I'll compose a full reply worthy of your fine illustrations and writings, but for now I leave you with this mind-virus: if you can find some way to double the structure's height, you just ~halved the shielding cost and thermal loss per unit of habitable volume. 8)

EDIT: typos
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 03/30/2019 08:15 am
What's wrong with digging a hole, putting the hab in and pushing the ' dirt ' straight back on top ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/30/2019 02:17 pm

The mass of the residual explosives is negligible, no?


According to Nobel (joined file), you need something like 1 kg of explosive per tonnes of rock for blasting for mid to hard rock.

Example, TNT:   C6H2(NO2)3CH3; → : 7C + 5H + 3N + 6O    (from Wikipedia)  so perhaps not that much residuals, most of these are gases, but there are always side reactions. So I don't really know.  freshly broken rock is often acid, and there is a lot of sulfur on Mars, so I expect the excavation/habitat site will have to be checked for acidic reactions.  No doubt there are spots on Mars with good properties.

So for 50 000 tonnes of rock, or 25000 m3 of base, you would need 50 tonnes of explosives.  Or about 25 million $ worth of transportation costs.  Not that much.  A roadheader operates at about 30 m3/hr, perhaps about 50 000 m3 per year at 2400h per year.  Probably optimistic, but the roadheader should operate for up to 10-20 years and mass 100 tonnes, so it beats explosives after two years, plus it produces much finer rock.  But it's obviously not a clear cut decision what could be used on Mars. 

I guess need a first visit with some nice pilot plants, small crushers and labs before speculation can become action. ;)

Image of an early cellular colony.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/30/2019 02:45 pm

The mass of the residual explosives is negligible, no?


According to Nobel (joined file), you need something like 1 kg of explosive per tonnes of rock for blasting for mid to hard rock.

Example, TNT:   C6H2(NO2)3CH3; → : 7C + 5H + 3N + 6O    (from Wikipedia)  so perhaps not that much residuals, most of these are gases, but there are always side reactions. So I don't really know.  freshly broken rock is often acid, and there is a lot of sulfur on Mars, so I expect the excavation/habitat site will have to be checked for acidic reactions.  No doubt there are spots on Mars with good properties.

So for 50 000 tonnes of rock, or 25000 m3 of base, you would need 50 tonnes of explosives.  Or about 25 million $ worth of transportation costs.  Not that much.  A roadheader operates at about 30 m3/hr, perhaps about 50 000 m3 per year at 2400h per year.  Probably optimistic, but the roadheader should operate for up to 10-20 years and mass 100 tonnes, so it beats explosives after two years, plus it produces much finer rock.  But it's obviously not a clear cut decision what could be used on Mars. 

I guess need a first visit with some nice pilot plants, small crushers and labs before speculation can become action. ;)

Image of an early cellular colony.
Modern explosives tend to be mixtures of compounds such as Pentaerythritol tetranitrate and RDX with plasticisers (Semtex) but may also include ammonium nitrate, TNT, aluminium and many other compounds. So the nature of the exhaust gases can be complex, but it would not matter as they would disperse quickly and are unlikely to cause any issues.

That said I would have thought that the best way of blasting on Mars would be to use liquid methane and liquid oxygen which could be manufactured on site. Just bring some light weight containment vessels. The rock on Mars is also likely to be highly fractured due to impacts so would be much more easily blasted than some rock on Earth.


I don’t think that there would be any problem from acidic rocks. Whatever the habitat is made of it will have to be resistant to the local environment and very rugged to have loads of rock dumped on top of it. Also at the very low temperatures that are likely any chemical reactions would run very slowly anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/30/2019 06:13 pm
Another view of the simple buried cellular outpost.
Not large enough to be a colony yet.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/30/2019 08:49 pm
lamontagne, how are all of those habs for the "Cordoba Mosque" brought to Mars? Are they flatpacked and assembled there? I can imagine the domes stacked together like so many breakfast bowls. - Because, "as is" only a few will fit in the Starship.

I used to think that a roadheader is the logical tunnel digger to bring to Mars because of its versatility. But TBC seems focused on TBMs, so...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/30/2019 09:58 pm
lamontagne, how are all of those habs for the "Cordoba Mosque" brought to Mars? Are they flatpacked and assembled there? I can imagine the domes stacked together like so many breakfast bowls. - Because, "as is" only a few will fit in the Starship.

I used to think that a roadheader is the logical tunnel digger to bring to Mars because of its versatility. But TBC seems focused on TBMs, so...
I expect a light carbon fiber version would come from Earth at first, flat packet and assembled on site, to be replaced as soon as possible by a locally produced steel.
The original mosque was something like that, with the first part more luxurious and higher quality, with the latter sections larger, but more cheaply built.  The older parts have two colored visible bricks, while the latter ones are just painted on.

The problem I have with tunnel boring machines are junctions, or nodes.  I think a colony needs a lot of junctions, and I'm not certain a TBM is the best tool for that. 
No doubt the future work of TBC will develop technologies that may be applicable to other types of machines.  And Musk changes ideas if needed, as we know.
I wonder of roadheaders make debris that is really suitable for Compressed Earth Blocks.  Perhaps if the source is really sandstone, but perhaps not for harder rock.  Boring machines seem to produce finer material.

Don't expect hexagons to survive the design phase.  They are cool to work with, and probably stronger, but rectangles are more practical for furnishings.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/30/2019 10:00 pm
Sorry for the lateness of this reply, net was down.


Another cellular structure, closer to what Twark Main as been proposing.
Inspiration is the Cordoba Mezquita, one of my favorite building in the world.

The cells could vary in size, and eventually create much larger spaces.
I think it's a good compromise between a pressure vessel and a compression structure.  And as it would be steel on Mars, if could have some really light columns/vertical tension members.
I expect the dome would be a double wall, with a structural interior and a ribbed vault holding multilayer insulation,, with an outer covering preventing the insulation from being crushed.
Safety walls can be set more or less arbitrarily as needs require.
The outer walls/cells could be domes and transparent tubular sections.

Wow, thanks lamontagne for your interest and time in making this.

A true masterwork of concision. You convey in a few short sentences what took me many paragraphs. "A picture is worth..."

Thank you also for sharing the beautiful images of original Cordoba Mezquita. Surely you must have posted these before, because that's exactly how I felt the large interior spaces should feel. I do think the hab will have a lot of "regular height" spaces too, probably in roughly an 80/20 volume allocation.

I agree with double walls. That level of redundancy makes sense for oil tankers (where a leak can results in loss of life and other huge problems), and imo for the same reasons it will make sense for life-critical pressurized habs.

A good idea imo would be prefabricated sections that bolt together, avoiding in-vacuo welding and NDI which must either be performed by a human worker in a pressure suit or by advanced robotics (bolting is way faster and less risky, which is the same reason they're used in terrestrial prefab truss systems). Early Earth-imported rigid parts could be stacked compactly in their payload carrier. Even later when manufacturing is done on Mars, you can perform that work in a shirt-sleeve pressurized factory environment. So we'll probably see bolted interfaces between big modular sections.

Bolts also mean you can pressure test early habs on Earth, then disassemble them and ship them to Mars. "Test what you fly."

How big is the largest hexagon dome segment that can fit through Starship's payload door? For early habs that might be the limiting constraint on cell size.

I believe in the "attic" space those panels between cells should have webs to form small bowstring trusses between cells, helping to transfer roof loads onto the two columns. Not structurally necessary during tensile operation, only if pressure is lost.

The thin steel hexagonal dome segments will work very well under tension, but as a contingency compressive dome it's limited by rigidity. Since you have quite sensibly chosen a double-wall design, I presume that it features notional internal stringers connecting both walls into a single structural panel. This provides the necessary profile thickness and rigidity at a minimum mass penalty, and the beautiful part is there's nothing to model in 3D. :D

As for the roof radiation shield, it might be acceptable for it to slope upward at the angle of repose. From the exterior it might be made to look rather like a Parisian block house.

(https://i.imgur.com/vbXF0XN.jpg)

I imagine that the entire roof shield might be covered in a flexible ME-MLI insulating blanket (for the thermal mass reasons mentioned). Also it would look prettier. :) You can print any pattern you want on the outside (albedo, visibility, solar heating, and radiative cooling considerations permitting), so picture Paris, or Amsterdam, or California Mission Style roofs.

If this thermal covering were combined with a tension structure, it might support overhanging bulges of regolith around the perimeter for superior radiation shielding. Sort of like the aforementioned above-ground pool restraining structure, but with the pool "hoops" flipped sideways and the semi-circle sagging under gravity. Essentially one big sandbag. To allow craning regolith on top it needs to be assembled in three sections: structural tension fabric walls, a grid of cables to support the top of those walls during regolith shield installation crane ops, and finally the "fitted sheet" switchable ME-MLI thermal blanket that goes over the entire top and sides, folding under and attaching to the steel structure.

Again the principle at work here is to always use pure tension for structural functions when possible, to optimize shipping cost for imported material and embodied energy for ISRU tensile materials. Cheaper ISRU compressive materials are used where appropriate (footers, pure-compression columns, etc), but that material too should be mass-optimized. Akin's Law #26 (Montemerlo's Law) applies: "Don't do nuthin' dumb." :)

For more on why tension structures tend to be more mass-efficient, I recommend researching Buckminster Fuller's concept of dymaxion structures and designs. Short for "dynamic maximum tension," (as we know making the strain uniform and maximum everywhere produces the most mathematically mass-efficient structures, though obviously real-world engineering is sliiightly more complicated).

Dymaxion house (https://www.bfi.org/about-fuller/big-ideas/dymaxion-world/dymaxion-house) was a 3000 lb prefab aluminum house that heated/cooled/powered/dusted itself, required no repainting or reroofing, and ; typical houses weigh)

https://www.bfi.org/about-fuller/big-ideas/dymaxion-world/dymaxion-bathroom (prefab bath simply bolts together from four pieces, "fog gun" shower uses 1 cup (250 mL) water; the principle is not a scaled-down pressure-wash, but a scaled-down compressed air duster using tiny fog droplets and triggered-in solvent to mobilize dirt and oils, and heat lamps to warm the skin; more here (https://web.archive.org/web/20060709000040/http://memeticdrift.net/bucky/eik_session_11alt.html))


More of the same.

In a way it's just a steel frame building with a number of domed roofs, that doesn't need to worry about water pooling in the joints.  Plus a weird inverted domed structural steel floor.

Oof, you got me. The idea struck me while idly gazing up at the steel deck truss structure in a recently constructed medium-box store. I thought to myself "hey, if you built these columns a little closer..." :D

[digression] If you take the time to look carefully at these (ubiquitous and 'boring') structures, you'll see that from a structural perspective they're space-filling dendritic fractals. Or more accurately, area-filling, because for a roof the design goal (to the first approximation) is supporting the entire maximum design snow drift/wind/rain load wherever on the roof it occurs. So the entire area must be uniformly strong.

What do I mean by dendritic fractal? Big words, but it basically just means "tree shaped." The building footprint is filled with a grid of large vertical I-beam columns (these are like the tree "trunks"). Running between these columns are large horizontal trusses (the main "limbs", though not perfectly analogous because these connect "trunks" together). Perpendicular to those large trusses run rows of smaller trusses to "fill in" the area between them (the "branches"). Finally the "leaves" are perpendicular corrugated metal that fills in between the small trusses. Concrete is poured on top, and this composite structure provides a structural platform for installing the weatherproof roof system. This fractal has N=3 since there are three levels excluding leaves, but an actual mature tree has N=7 or more, with each level having a branching favtor. Because biological trees have been subject to aggressive structural mass-optimization by natural selection (as are composite steel deck truss systems by competition between firms), this suggests that the topologically optimum fractal structure might have N=3-7.

But then again, biological trees may be optimizing for different requirements, such as gathering sunlight and optimizing gas exchange. A deciduous tree standing alone in a field will generally solve this by growing a "shell" of leaves on the outside (each leaf is subject to wind loads, so this is sorta like the roof truss??), but then deciduous trees are instead located in a dense stand they'll generally just carve up the canopy space between them (the gaps or "crown shyness (https://bigthink.com/robby-berman/patterns-overhead-show-tree-intelligence-at-work) is a natural contact-mediated growth response to avoid wind damage; ie trees know when they bump into each other in high winds and plan their future growth accordingly, with kin selection et al). But I digress further.

I'm still not sure whether to count the column-to-beam transition as a branching level, but I do. So currently the cellular hab has N=3, with vertical column trunks, horizontal connecting trusses limbs, radial stringer branches (not shown), and the sheet steel dome is the uncounted leaves. This heuristic (or more accuratly, WAG) suggests that we might add fractal layers to improve the structural optimality. Or this whole idea might be a dead-end because of some consideration I haven't thought of.

One suggestion: perhaps it would be more optimal if there were six thickened "spoke" stringers going from the hexagon corners to the center? I believe the mass-optimal roof curvature (ie when the dome surface, stringers and trusses are all simultaneously optimized) is not quiiite spherical due to the hexagon's deviation from a circle (but it's also not six cylindrical sections either, the optimum is in-between those), and this topology addresses that stress concentration.


That's all I have for you right this second.  I've assuredly left out a great many things, and maybe I'll even remember some of it...

Huge thanks go again to lamontagne for the incredible renderings. Between this thread and low tech/ag scaling your work is legend, and it's such a treat to see my humble concept immortalized as a genuine lamontagne™. :D Hats off to you, sir.




What's wrong with digging a hole, putting the hab in and pushing the ' dirt ' straight back on top ?

AKA cut-and-cover

Nothing particularly wrong, it's just that not digging a hole (and skipping straight to the step of pushing the most conveniently available dirt on top) is likely to be cheaper in most situations. If you can avoid digging the under-hab-hole, do that instead. Even if you simply dig a hole in identical ground right next to the hab (not under it), that's still preferable because you only move dirt once instead of twice!

As a further cost benefit you need expend no effort in making a neat hole, but the above paragraph alone clinches it for me. Goodnight sweet Cut-and-Cover; we hardly knew ye! ;D


The underlying principle is simple: don't do unnecessary work, and don't have unnecessary components or systems. In general, make sure there's "nothing left to take away" (Law #35).

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/30/2019 10:15 pm
Minor point:

We don't build houses on sand for obvious reasons. And a 100 meter tall gravity pile sand dune holds a lot of sand.

Ew, no. Do not use dune-sand for fill. Terrible cohesion, bad to work with. Yuck.

That's why I didn't understand why you were so obsessed with bringing in fill from somewhere else. It's not going to be easier to dig up the same material somewhere else. But you're picturing the habs on good ground, with the fill from loose ground elsewhere. No. You'll be living with that decision forever. Pretty much by definition, good fill comes from good ground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/30/2019 10:27 pm
Even if you simply dig a hole in identical ground right next to the hab (not under it), that's still preferable because you only move dirt once instead of twice!

So now you've got a hole, and a hundred more habs scheduled to install, and you don't think someone will look at that hole, dug down to material that had been pre-compressed by 5m of regolith above, and think... hmmm... I could start over to prepare an entirely new site... or...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/31/2019 12:34 am
Minor point:

We don't build houses on sand for obvious reasons. And a 100 meter tall gravity pile sand dune holds a lot of sand.

Ew, no. Do not use dune-sand for fill. Terrible cohesion, bad to work with. Yuck.

That's why I didn't understand why you were so obsessed with bringing in fill from somewhere else. It's not going to be easier to dig up the same material somewhere else. But you're picturing the habs on good ground, with the fill from loose ground elsewhere. No. You'll be living with that decision forever. Pretty much by definition, good fill comes from good ground.

"Fill" in the geotechnical sense is not necessary, just an unconsolidated rubble pile. You won't be driving on the roof to compact it because there's no need to support the weight of a building on top of the radiation shield. Buildings don't stack. The shield just needs to 1) have mass and 2) sit there. Settling over time is fine.

Actually sand may work be even better. It could be possible to somehow "pipe" it into the overhead sandbag with no crane needed. At this point there's a natural temptation to naysay my brainstorm with a quick objection or three and then quit, but perhaps those considerable brainpowers could be further utilized afterwards to imagine solutions as well? Thinking up problems is the easy half. :D

Even if you simply dig a hole in identical ground right next to the hab (not under it), that's still preferable because you only move dirt once instead of twice!

So now you've got a hole, and a hundred more habs scheduled to install, and you don't think someone will look at that hole, dug down to material that had been pre-compressed by 5m of regolith above, and think... hmmm... I could start over to prepare an entirely new site... or...

And at the "hundreds of habs by Friday" stage that makes perfect sense, and it would sure be a classy problem to have on Mars!

My point is, don't use that logic to conclude that the first hab must necessarily use that technique. No need to ship an excavator for the first hab, just a dozer. No need to assume excavator per-tonne material costs or fracture energy in calculating the cost of the first rad shields.

Choose whatever you think the best/most convenient/cheapest source is. How can I make it any clearer? I'm not picking for you, just offering a menu. What you choose will (obviously) be based on site-specific, situation-specific, and client-specific criteria.

This is Burger King. Have it your way.™
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/31/2019 03:51 am
At this point there's a natural temptation to naysay my brainstorm with a quick objection or three and then quit, but perhaps those considerable brainpowers could be further utilized afterwards to imagine solutions as well? Thinking up problems is the easy half.

Right back at ya.

My point is, don't use that logic to conclude that the first hab must necessarily use that technique.

This thread isn't about the first hab on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/31/2019 03:10 pm


One suggestion: perhaps it would be more optimal if there were six thickened "spoke" stringers going from the hexagon corners to the center? I believe the mass-optimal roof curvature (ie when the dome surface, stringers and trusses are all simultaneously optimized) is not quiiite spherical due to the hexagon's deviation from a circle (but it's also not six cylindrical sections either, the optimum is in-between those), and this topology addresses that stress concentration.


I think that is the structural function of the six tension members linking the top of the columns and forming the square openings. They are acting as a continuous tension structure that should not deform as they cannot increase in diameter.  This structure is very poor laterally, however.  But Mars may not have all that many lateral loads.  No Marsquakes, no wind.  But no doubt there should be some lateral bracing.  Internal diaphragms, serving as pressure safety walls might serve that purpose.  I guess they could be pretty far from one another though.
Glad you like the images.  I try to keep an open mind and not just push my own ideas.  The Cordoba Mezquita reference just arose spontaneously from the first model I did for the cellular idea.  I looked at the model and told myself: 'I've seen this before.'   Call it an emergent property :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 03/31/2019 03:53 pm
I love this hexagonal cell idea. Going to Mars to evolve into Bees.
I'm throwing some ideas and observations out here. No complete solutions.

First, it is essentially very strong.  (if more material is left around the square openings ...) And mathematically beautiful. It also has a cultural history on Earth. Instead of being superseded by rectangular structures because of the convenience of the right angle, it could become a cultural evolution (from earth), affirming the engineering rationality, rather than convenience of the cube. The hexagon lends itself to shared spaces, unlike the square which has corners where mixing is restricted.

Strength: space is not always better by having an unobstructed large space. The lateral stability mentioned can be solved by having some of the corner pillars widened by a flat sheet partially closing the three adjacent doorways at 120 degrees apart. This could also be done with wires, rods or thin beams.
The same principals could be used to make a similar structure out of "compressed earth" blocks. Several specific moulds would comprise the specialised blocks needed, for the rose, ribs, top of the column, etc etc... Larger pillars would take the weight of radiation cover. This is obviously not an initial solution, and pressurised interior verses supported weight is an issue!

Similarly marscrete (I assume one will be developed that is curable and effective)  could be cast over the cells, or over a similar larger former, and the cells fit below with clearance. A change in design would allow for the solid columns required.

I expect getting used to living and working at 7psi instead of 14 is discussed above... ISTM this would have a big impact on design.
Rather mad .... structural use of ICE if water was sufficiently easy to mine! I was thinking how such a hexagonal structure could be strong when pressurised, and when depressurised, not collapse.
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 03/31/2019 05:57 pm
I expect getting used to living and working at 7psi instead of 14 is discussed above...

Nope. Fire. Bad.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 03/31/2019 07:06 pm
I assume you mean the partial pressure of oxygen is greater so higher fire risk.... But - and I'm sure this has been discussed...  on earth people live in the Andes etc, and athletes deliberately train up mountains completely safely after acclimatisation .... in lower pressure and lower oxygen, 0.6 atm and 0.6 of the O2 at 3000m altitude. ...   Still I don't want to derail the thread. I will try to get round to looking it up.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/31/2019 09:00 pm

The mass of the residual explosives is negligible, no?


According to Nobel (joined file), you need something like 1 kg of explosive per tonnes of rock for blasting for mid to hard rock.

Brilliant, thank you for the excellent information dense source. Funny and I was just mentioning Alfred Nobel's Original Recipe Fyne Patent Blasting Powder And All-Purpose Boil Ointment, too. He really should've renamed it to something more catchy... ;)

If 1:1000 is the leverage ratio for solid rock, loosening lightly-compacted marsdirt should be even better. Naturally there's also the added cost of drilling, but this is a great start.

freshly broken rock is often acid, and there is a lot of sulfur on Mars, so I expect the excavation/habitat site will have to be checked for acidic reactions.  No doubt there are spots on Mars with good properties.

AKA acid rock drainage. But no sulfur-eating bacteria/free oxygen, no sulfuric acid. Unless I'm missing something?

So for 50 000 tonnes of rock, or 25000 m3 of base, you would need 50 tonnes of explosives.  Or about 25 million $ worth of transportation costs.  Not that much.  A roadheader operates at about 30 m3/hr, perhaps about 50 000 m3 per year at 2400h per year.  Probably optimistic, but the roadheader should operate for up to 10-20 years and mass 100 tonnes, so it beats explosives after two years, plus it produces much finer rock.  But it's obviously not a clear cut decision what could be used on Mars.
 

Not bad. Per your spreadsheets the PV panel to power the roadheader only masses 15 extra tonnes (250 kW average consumption).

Of that 250 kW, do you have any idea how much goes to the cutting head and how much goes to scooping up the rubble? I'm trying to constrain the numbers on those ISRU explosives.



Image of an early cellular colony.

Love it.

Your gravity pile is the essence of simplicity, and deletes many unnecessary components. For low-rise structures this is definitely the way to go. However I am also curious what the optimal solution looks like when scaled to 40 stories tall and eight city blocks wide. :o An enclosing gravity pile would be excessive at that point, hence my suggestion of hanging sandbags. Different solutions are appropriate for different scales.

I presume the windows face south for maximum insolation? Plants might be incorporated into the interior layout rather like an Earthship, so a single window might perform multiple simultaneous functions: illumination, exterior view, solar gain, plants for psychological benefit/supplemental food/some air cleaning/some water recycling. Obviously plants cannot (yet?) be the only life-support, only a tiiiny fraction, but experimental data can be gathered to help design better future Mars plant growing systems.

My "cheap bootstrapping" base case is to land such a prefab structure, assemble it, cover it, install life support, and use it as living space, lab, workshop, and teleoperation base camp.

Naturally a cost and mass-optimized building wouldn't require large windows. With sloping sides, the corners become the natural places for the underlying structure to "peek out" and so locate high viewing cupola 'lounges' and ground-level airlocks. Corner airlocks also means you most rooms have multiple routes to an exit (which of course may or may not be useful depending on the nature of the emergency).

If you use multiple levels the number of imported cells can be reduced proportionally. To my eye the depicted height of Mezquita Cordoba might be divided into three floors:  individual apartment spaces in the lofts, ground level workshops and public spaces (some of which are high bays taking up 2-3 levels), and office space in the mid-level.

Naturally the "basement" space beneath the lowest floor needn't be wasted either, as I'm sure you agree. It might house infrequently-accessed equipment, overflow storage, smuggle stuff past Imperial Stormtroopers, or find some other use. Pressurized conditioned volume is precious and expensive on Mars, and every cubic centimeter will be utilized, that will certainly be seen to!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/31/2019 09:26 pm
At this point there's a natural temptation to naysay my brainstorm with a quick objection or three and then quit, but perhaps those considerable brainpowers could be further utilized afterwards to imagine solutions as well? Thinking up problems is the easy half.

Right back at ya.


Did I naysay anyone's ideas? Sorry that was not my intent, but to explain why my own ideas are different, in response to specific criticisms.

My point is, don't use that logic to conclude that the first hab must necessarily use that technique.

This thread isn't about the first hab on Mars.

Not true. The thread starter asks:


[snip]

These assumptions lead to the conclusion that the very first humans on Mars (on a long-stay mission) will be building habitats. Agree / disagree with this conclusion?

What kind of amazing, spacious habitats can we envision? What selection of habitat building components would you want in your flat-packed containers?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 04/01/2019 04:49 am
So I interrupt this regularly scheduled oxygen vs. pressure discussion to ask:
Who else here has submitted for the Mars Society Mars Colony Design Competition?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/01/2019 10:54 am
First off, Starship steel hull radiation concerns. For a ship at 1AU, the GCR dose (2010 Solar Min) is thus:

5g/cm^2 Al (1.85cm thick): 1.994E+00 mSv/day
4.4g/cm^2 Graphite epoxy (3cm thick): 1.844E+00 mSv/day
7.85g/cm^2 Stainless steel (1cm thick): 1.976E+00 mSv/day
15.7g/cm^2 Stainless Steel (2cm thick): 1.660E+00 mSv/day

For the Stainless Steel, I used 70% Fe, 18% Ni, 10% Cr, 2% Mo. I figured the carbon wasn't worth figuring in. It took a while to crunch the numbers to generate the material database as is. Starship hull is said to be 6mm thick. The 2cm thick figure was used to take into account different angles and extra structural material.

Going back to regolith shielding, this is what OLTARIS uses for Martian regolith.

O2Si 51.2 %
Fe2O3 9.3 %
Al2CaK2MgNa2O7 32.1 %
H2O 7.4 %

Mars surface calculations for GCR are (2010 Solar Min, 0km elevation):

Ramsar, Iran comparison: 9.0E-02mSv/day
ICRP "very high" natural background radiaiton: >1.3E-01mSv/day
Curiosity baseline: 6.6E-01mSv/day
2m thick water sphere: 1.854E-01 mSv/day   
3m thick water sphere: 1.236E-01 mSv/day
2m thick regolith sphere: 2.269E-01 mSv/day   
3m thick regolith sphere: 1.141E-01 mSv/day

Note that these models are indicative only. The code has not really been validated for very thick slabs. Note that these values are also computed for spheres, ie also shielding against radiation from the sides and backscatter from the ground. A hab with only the roof shielded would have a partial degree of protection. Assuming that, in the middle of a cube, the roof is covered, that yields 29.2% coverage (sky visible hemisphere is covered from 45 degrees up).

As we've seen, even high areal densities do not perform well against galactic cosmic radiation. So the sides receive only a minimal boost over the 20g/cm^2 atmospheric shielding, only reaching 100g/cm^2 closer to the horizon. So a regolith roof would only cut out ~0.2mSv/day of the ~0.66mSv/day dose.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/01/2019 12:08 pm
Regarding an oculus, I recently visited a place with a 35m diameter dome and a ~17m oculus. From my estimation, I'd say the oculus covered about 10 degrees of sky at zenith. This translates to 0.38% coverage of the sky hemisphere (and hence roughly your daily rad dose). There was enough light shining in to light up the place quite comfortably since the sunlight comes in in a beam, and there was a decent amount of skyshine along with it.

Handy online calculator for this sort of thing:

http://www.ambrsoft.com/TrigoCalc/Sphere/Cap/SphereCap.htm

Although the spherical cap equations are really simple: 2piRh = pi(r^2+h^2), r = sqrt(2Rh - h^2), sintheta = r/R

(http://www.ambrsoft.com/TrigoCalc/Sphere/Cap/Images/cap.png)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/01/2019 01:13 pm
So I interrupt this regularly scheduled oxygen vs. pressure discussion to ask:
Who else here has submitted for the Mars Society Mars Colony Design Competition?
I did :-)
https://sites.google.com/view/estepona-on-mars
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/01/2019 01:34 pm
So I interrupt this regularly scheduled oxygen vs. pressure discussion to ask:
Who else here has submitted for the Mars Society Mars Colony Design Competition?
I did :-)
https://sites.google.com/view/estepona-on-mars

That's amazing. The way you designed those interiors, it actually looks like somewhere where people can imagine living.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 04/01/2019 11:53 pm
So I interrupt this regularly scheduled oxygen vs. pressure discussion to ask:
Who else here has submitted for the Mars Society Mars Colony Design Competition?
I did :-)
https://sites.google.com/view/estepona-on-mars

Oh snap! That's amazing! I wish I had your skill with SketchUp, a picture really does say 1000 words!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/02/2019 12:05 pm
So I interrupt this regularly scheduled oxygen vs. pressure discussion to ask:
Who else here has submitted for the Mars Society Mars Colony Design Competition?
I did :-)
https://sites.google.com/view/estepona-on-mars

That's amazing. The way you designed those interiors, it actually looks like somewhere where people can imagine living.
Glad you like it.  I guess I finally managed to realize the title of the thread  :)
Don't know if the pretty pictures will carry much weight with the judges though.  Governance and economical sections of the paper are not very strong, although I do feel people tend to overthink the governance model for a group of 1000 people.
Added a few pictures to the website.  Really loooong renders.  Trees and plants are incredibly complicated objects.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/02/2019 12:22 pm
First off, Starship steel hull radiation concerns. For a ship at 1AU, the GCR dose (2010 Solar Min) is thus:

5g/cm^2 Al (1.85cm thick): 1.994 mSv/day
4.4g/cm^2 Graphite epoxy (3cm thick): 1.844 mSv/day
7.85g/cm^2 Stainless steel (1cm thick): 1.976 mSv/day
15.7g/cm^2 Stainless Steel (2cm thick): 1.660 mSv/day

For the Stainless Steel, I used 70% Fe, 18% Ni, 10% Cr, 2% Mo. I figured the carbon wasn't worth figuring in. It took a while to crunch the numbers to generate the material database as is. Starship hull is said to be 6mm thick. The 2cm thick figure was used to take into account different angles and extra structural material.

Going back to regolith shielding, this is what OLTARIS uses for Martian regolith.

O2Si 51.2 %
Fe2O3 9.3 %
Al2CaK2MgNa2O7 32.1 %
H2O 7.4 %

Mars surface calculations for GCR are (2010 Solar Min, 0km elevation):

Ramsar, Iran comparison: 0.09 mSv/day
ICRP "very high" natural background radiaiton: >0.13 mSv/day
Curiosity baseline: 0.66 mSv/day
2m thick water sphere: 0.1854 mSv/day   
3m thick water sphere: 0.1236 mSv/day
2m thick regolith sphere: 0.2269 mSv/day   
3m thick regolith sphere: 0.1141 mSv/day

Note that these models are indicative only. The code has not really been validated for very thick slabs.

Awesome, thanks for running these numbers. In the above quote I took the liberty of translating the scientific notation, since I find it easier to read that way.

Out of curiosity how easy do you find the software is to use? What kind of computation time does it take?

Note that these values are also computed for spheres, ie also shielding against radiation from the sides and backscatter from the ground. A hab with only the roof shielded would have a partial degree of protection. Assuming that, in the middle of a cube, the roof is covered, that yields 29.2% coverage (sky visible hemisphere is covered from 45 degrees up).

As we've seen, even high areal densities do not perform well against galactic cosmic radiation. So the sides receive only a minimal boost over the 20g/cm^2 atmospheric shielding, only reaching 100g/cm^2 closer to the horizon. So a regolith roof would only cut out ~0.2mSv/day of the ~0.66mSv/day dose.

Yes I would expect a cube-shaped building not to work very well, for exactly the reasons given. This is why I planned for buildings with very wide geometry, not cubes. This can be conceived as a single building, or by tiling those cube buildings close together (meaning that for the same low low monthly payment shielding mass as the ineffective "lone cube with hat" example, a "tiled cube with hat" gets free side shielding from the hats of neighboring/abutting buildings). You need shielding on the side too, but it's more costly per cube, so to minimize shield mass/cost you want to maximize the area-to-perimeter ratio, ie make the building footprint larger.

If the hab is eg 10x longer on a side the math looks much better. But even the non-optimized geometry of a cube shows the bias toward overhead shielding: for only shielding 1/5th the total cube area (20%) you got .2/.66 (30.3%) as much shielding effect.

I've always assumed there will be shielding on the side. But less thickness is needed overall, because A) the total flux is lower by at least 1/2, and B) the peak radiation direction isn't straight on so there's some "cosine gain." You can make it thicker of course (if that's "free"), but there's no requirement saying we should spend anything extra doing so.


As far as I can tell the math says you simply want to scale the hab larger-and-larger and flatter-and-flatter. All your unit costs get lower. On the largest scale it would be like a city except with all the skyscrapers merged together. At that scale of 40-100 stories I picture a hanging sandbag wall with a gravity pile at the base. An interesting question is, how high up the gravity pile should go as a function of height h in order to optimize cost? This trades between the relative cost of the gravity pile (with earthmoving marsmoving costs scaling as h^2) vs the sandbag wall -- with sandbag cost scaling as h, suspension cable costs scaling as h^2 (assuming they're not attached to the building itself, which is my baseline plan), and structural constraints based on total weight the building perimeter can support.

And somewhere in this trade space you just build a retaining wall out of compressed regolith blocks. A lot less regolith because the pile angle is steeper, but adds the cost of the retaining wall. 

Sad to say the simulation of a cube with a roof shield doesn't help answer my original query:

Going back to radiation shielding materials, OLTARIS tells me that a 2m thick dome (well, sphere) on Mars reduces the radiation dosage inside to about 1/4 of the unshielded surface dose. So that's 20g/cm^2 of CO2, 200g/cm^2 of H2O and the surface blocking half the incident GCR is 300cm of regolith (this is modeled for backscatter).

Next I'll try with 200g/cm^2 of Martian regolith and then try a mix of 100g/cm^2 ice then 100g/cm^2 regolith to see what that does.

How does the 2m thick sphere compare with my 3.62m thick infinite horizontal slab? 2m infinite slab? In general what thickness of slab provides equivalent shielding to a 2m sphere?

My geometric intuition says it's <3.62m, which would imply that large flat slabs, not hemispheres, are the optimal shape for city-size radiation shields.

Is it possible to tell the software to do an infinite flat slab approximation? Or is it possible to model a "flattened cube" aka rectangular prism 100x longer and wider than it is tall (probing levels in the center not the edge)? That would help settle this question of whether a grid of spheres vs. a grid of cubes-with-hats is a more mass-optimal geometry for city-size shields, and unfortunately I don't have access to OLTARIS to do the calculation myself. Pretty please Lampyridae? :-[... :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 04/02/2019 01:15 pm
So I interrupt this regularly scheduled oxygen vs. pressure discussion to ask:
Who else here has submitted for the Mars Society Mars Colony Design Competition?
I did :-)
https://sites.google.com/view/estepona-on-mars

That's amazing. The way you designed those interiors, it actually looks like somewhere where people can imagine living.
Glad you like it.  I guess I finally managed to realize the title of the thread  :)
Don't know if the pretty pictures will carry much weight with the judges though.  Governance and economical sections of the paper are not very strong, although I do feel people tend to overthink the governance model for a group of 1000 people.
Added a few pictures to the website.  Really loooong renders.  Trees and plants are incredibly complicated objects.

I know! 1,000 people sounds like a lot.... until you're in a theatre with 2,000 people with room to spare... nowhere near enough for a new branch if humanity...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/02/2019 02:33 pm
Going back to radiation shielding materials, OLTARIS tells me that a 2m thick dome (well, sphere) on Mars reduces the radiation dosage inside to about 1/4 of the unshielded surface dose. So that's 20g/cm^2 of CO2, 200g/cm^2 of H2O and the surface blocking half the incident GCR is 300cm of regolith (this is modeled for backscatter).

Next I'll try with 200g/cm^2 of Martian regolith and then try a mix of 100g/cm^2 ice then 100g/cm^2 regolith to see what that does.

How does the 2m thick sphere compare with my 3.62m thick infinite horizontal slab? 2m infinite slab? In general what thickness of slab provides equivalent shielding to a 2m sphere?

My geometric intuition says it's <3.62m, which would imply that large flat slabs, not hemispheres, are the optimal shape for city-size radiation shields.

Is it possible to tell the software to do an infinite flat slab approximation? Or is it possible to model a "flattened cube" aka rectangular prism 100x longer and wider than it is tall (probing levels in the center not the edge)? That would help settle this question of whether a grid of spheres vs. a grid of cubes-with-hats is a more mass-optimal geometry for city-size shields, and unfortunately I don't have access to OLTARIS to do the calculation myself. Pretty please Lampyridae? :-[... :)

I'm afraid I cannot "settle" a question. OLTARIS is code, effective dose of cosmic radiation is still very lacking in understanding and we're not even sure how much radiation can be considered bad. What I can safely say is that the first criteria will be safety, followed by relative cost and ease of manufacture - these two are closely correlated. Inflatable structures are currently more expensive than the traditional aluminium tin cans, because they have multiple layers and require stitching. I'm not making this up, this is according to NASA and ILC Dover. I can say that OLTARIS gives me these results... that's it. I don't trust it for thick simulations, but there is nothing else. I can say that ice looks competitively better than regolith for shielding, but how thick the shields really needs to be remains a thumbsuck.

OLTARIS treats everything as a sphere with thicknesses, as an XML format. There's a CAD importer to work these things out but I've yet to figure it out.

I can try and model a slab of loose regolith, but that means you have incorporated structure sufficiently strong enough to hold the slab off the ground as a tray, perhaps steel girders and thick steel plate on the sides. Or, some pantheon-like structure made with Martian bricks (as easy as packing into a rubber mould and hitting with a hammer - FeO acts as a binding agent).

If you mean loose regolith piled on top, it will most definitely not be a slab. The material will fill the divisions between each hot dog, and be thinner on top. The regolith will sit at the normal angle of repose, which is about 30 degrees on Mars. It will only start from the top of the outer hot dog arch. For a regolith depth of about 2m you will only get the inner hot dog fully covered by regolith. However, there as indicated previously, there will be sections of thick vertical coverage as the soil fills the cracks. You can eliminate this by the use of simple lightweight sheeting (see my soil arching discussions) but why? You are reducing shielding.

If the hot dog pack deflates, the loose regolith will be an unmitigated disaster. Remember that soil doesn't sit, it transmits forces, so even inflated connector tunnels can get crushed if the regolith piles on it wrong. This is why there is so much interest in building solid structures as opposed to simply burying them in dirt. So, a solid slab is the way to go.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/02/2019 02:55 pm

If you mean loose regolith piled on top, it will most definitely not be a slab. The material will fill the divisions between each hot dog, and be thinner on top. The regolith will sit at the normal angle of repose, which is about 30 degrees on Mars. It will only start from the top of the outer hot dog arch. For a regolith depth of about 2m you will only get the inner hot dog fully covered by regolith. However, there as indicated previously, there will be sections of thick vertical coverage as the soil fills the cracks. You can eliminate this by the use of simple lightweight sheeting (see my soil arching discussions) but why? You are reducing shielding.

If the hot dog pack deflates, the loose regolith will be an unmitigated disaster. Remember that soil doesn't sit, it transmits forces, so even inflated connector tunnels can get crushed if the regolith piles on it wrong. This is why there is so much interest in building solid structures as opposed to simply burying them in dirt. So, a solid slab is the way to go.

I wonder if there's a better design than vertical rectangles. I know you've talked about using hexagons, but that doesn't tessellate in 3D well without hexagonal prisims.

What about an octagon/square tessellated grid, with vertical layers alternating octagon and square? I'm away from any kind of modeling program to show what I mean, but basically each cell is a square at the bottom, an octagon at the waist (side length of square and octagon remain the same) and closes to a square at the top. Four  cells are attached to it at the same level, at the "corner" edges of the octagon, and 4 are attached half a level up and 4 half level down, their square base/top attached to where the octagon waist's form a square.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/02/2019 03:22 pm
quick MS paint- Top-down view of a single cell.
The triangle shapes on the corners are connections to same-level cells. (to properly tessellate, this requires a cutout in the top and bottom of the hab, but I don't think it affects much) The rectangles on the orthogonal sides are hatches+stairs between habs that are half-level displaced.

Overall, this approach produces more spherical habitations that still "soap bubble" together with flat walls. Vertical collums at the corners of the base can reinforce the structure vertically against the forces of pressure loss.

Edit: After further consideration, there are tetrahedral voids at the corners, exactly where the cutouts need to be for same level hatches. Stacked airlocks between cells should fill the void. (Hab 2 is a single level of habs, dark grey is outside/where half-level habs would fit. light grey is the  slope from octagon to square, with airlocks connecting habs- this area forms a void in a multilevel structure, but a larger airlock could fill the void with cubes)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/02/2019 07:34 pm
Nice.

A 12-sided polygon (dodecahedron, your garden variety D12 dice) will make a perfectly repeating solid with no voids. It so happens they had single dodecahedron structures in the SpaceX IAC presentation images.

The rhombic dodecahedron 3d-tiles more regularly though, giving something more like a floor whereas normal dodedachedrons would have weird angles to contend with.

(https://upload.wikimedia.org/wikipedia/commons/d/d9/Rhombic_dodecahedra.png)

(https://i.stack.imgur.com/O4uOP.png)

The rhombo-hexagonal dodecahedron (what a mouthful) 3d-tiles and gives continuous floors. Probably the best option.

(https://upload.wikimedia.org/wikipedia/commons/thumb/3/33/Rhombo-hexagonal_dodecahedron_tessellation.png/799px-Rhombo-hexagonal_dodecahedron_tessellation.png)

Plus there's some absurdly clever tessellation possibilities. Check these out, water bottles by Portuguese company Pedrita.

(http://pedrita.net/pedrita-wordpress/wp-content/uploads/2015/01/luso-h2-334.jpg)

(http://pedrita.net/pedrita-wordpress/wp-content/uploads/2015/01/luso-h2-336.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/02/2019 08:55 pm
Nice.

A 12-sided polygon (dodecahedron, your garden variety D12 dice) will make a perfectly repeating solid with no voids.
Er, Garden variety 12-siders are made of pentagons. I've got a handful of them, they dont make repeating solids.

The rhombic dodecahedrons look interesting, though.
Looks like the hexa-rhombic design makes furrows, that you have to go up a half-level to go down into the next row. There's no natural nexus, if you have a hexagon for a floor.

Perhaps if the hexarombic was hexes-vertical, with two floors inside, and stairs leading down through the lower faces?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/02/2019 09:23 pm
Nice.

A 12-sided polygon (dodecahedron, your garden variety D12 dice) will make a perfectly repeating solid with no voids.
Er, Garden variety 12-siders are made of pentagons. I've got a handful of them, they dont make repeating solids.

The rhombic dodecahedrons look interesting, though.
Looks like the hexa-rhombic design makes furrows, that you have to go up a half-level to go down into the next row. There's no natural nexus, if you have a hexagon for a floor.

Perhaps if the hexarombic was hexes-vertical, with two floors inside, and stairs leading down through the lower faces?

Ah snap, you're right. Too bad, they look kind of cool. I took the extremely scientific process of mashing some D12s together and they seemed to fit. Ah well.

But a two-floor hexarhombic sounds quite doable, and scales nicely whilst having a useable individual unit size.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/02/2019 09:48 pm
Nice.

A 12-sided polygon (dodecahedron, your garden variety D12 dice) will make a perfectly repeating solid with no voids.
Er, Garden variety 12-siders are made of pentagons. I've got a handful of them, they dont make repeating solids.

The rhombic dodecahedrons look interesting, though.
Looks like the hexa-rhombic design makes furrows, that you have to go up a half-level to go down into the next row. There's no natural nexus, if you have a hexagon for a floor.

Perhaps if the hexarombic was hexes-vertical, with two floors inside, and stairs leading down through the lower faces?

Ah snap, you're right. Too bad, they look kind of cool. I took the extremely scientific process of mashing some D12s together and they seemed to fit. Ah well.

But a two-floor hexarhombic sounds quite doable, and scales nicely whilst having a useable individual unit size.
The next question is what kind of hoop stress does an outer hexagon need to be protected from. As I understand your original concept, each exterior face gets it's own dome, to increase modularity over large dome construction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 04/02/2019 10:40 pm
Space filling polyhedra were brought up a while back, eg https://forum.nasaspaceflight.com/index.php?topic=41427.msg1614790#msg1614790

https://en.wikipedia.org/wiki/Category:Space-filling_polyhedra

One question I had at the time was, how hard is it to design a panel that can hold pressure from both sides? That implies a sort of flexible material that can change the direction it bulges in.

Is that the goal here, or is it just flexible modular volumes without internal panels, just the struts?
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/02/2019 10:49 pm
Space filling polyhedra were brought up a while back, eg https://forum.nasaspaceflight.com/index.php?topic=41427.msg1614790#msg1614790

https://en.wikipedia.org/wiki/Category:Space-filling_polyhedra

One question I had at the time was, how hard is it to design a panel that can hold pressure from both sides? That implies a sort of flexible material that can change the direction it bulges in.

Is that the goal here, or is it just flexible modular volumes without internal panels, just the struts?
The original concept for cubic structures with outer restraining hoops was way back in this thread:
"Amazing" imo would be a huge city grid covering many km², even if the individual buildings themselves were of a practical and cost-optimized design. Does "amazing" automatically imply "expensive?" Everyone seems to agree that underground habitation is doable (and it provides a cost backstop), but could a sufficiently well-designed above ground hab be even cheaper? Or faster to build/deploy?

Here's my humble attempt at a first principles approach. Rather than start with a desired shape and work backward, I'll start with a mass-efficient pressure vessel and work forward. Something more than the standard tuna can.

Imo this approach is justified because pressure restraint is by far the largest structural load (including holding an n meter thick regolith shield overhead), and most ISRU-derived structural materials will be expensive and should still be conserved as much as reasonably possible. Mining and processing on Mars is costly, even if it's cheaper than Earth imports. Ultimately it's about minimizing total lifecycle cost per square/cubic meter per year — energy, water, labor, imports, etc. 

Lacking a better name I call it... The Waffle Hab. :) See attached image.

It's a straightforward cellular pressure vessel with the cells aligned with individual rooms and levels. Cellular hab designs must have some optimal cell size, and this seems like a natural choice. Preferred initial implementation is inflatable so it can be acceptance tested on Earth, stowed in a small volume, and quickly deployed. This provides bulk volume for early missions without tying up too many personnel on construction tasks, or alternately it maximizes the output of a given size construction crew. Gradually it would transition to ISRU materials and manufacturing as changing costs dictate.

Advantages

It's a thin-walled pressure vessel having the same geometric efficiency as a cylindrical cross-section, but it creates vastly more human-accessible space (ie not just a big open void). Thin-walled vessels are pure tensile structures so they have high mass efficiency, such that even rigid habs should assume shapes like inflatables to minimize mass — think of the inflatable as a physical "form-finding" model for discovering purely tensile geometries.

A 40 meter long hab with this cross-section would provide 3000 m² of floor space, and if using Kevlar its pressure restraint would mass only 6.7 tonnes, or 9.4 tonnes for basalt fiber (assuming 4x safety factor and 100 kPa pressure). It needs an air bladder and anti-scuff layers too of course. Transhab used a CombiTherm liner for low permeability, but aluminum oxide sputtered films are thinner and have even lower measured leak rates (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080010625.pdf). Anti-scuff layer might be Nomex like Transhab, or non-structural glass fiber (since many sources of ISRU glass will likely contain high iron content).

The floor is held in high tension and supported at each internal wall, so even a non-rigid design would have very little sag. A rigidizing secondary floor structure could be added if necessary, but at the cost of increased mass, stowed volume, and deployment complexity. Hopefully this is not needed for most structures.

No heavy-duty rock anchors. The "basement" cavities would be insulated to minimize conductive heat loss and avoid destabilizing the permafrost (more an issue in dense city grids than for standalone buildings).

Water or regolith can go on top for radiation protection, and if necessary in the outer wall cavities. No buoyancy problems. A regolith shield might use waste from tunneling or water mining. A water shield could allow plants to grow under natural light in the "attic" space, or that volume might be used as a gravity-fed water tower and rad shield. It can also provide inexpensive volume for fully-artificial illumination, with tensile supported hydroponics, flexible tank bioreactors, and suspended lights and ductwork for an ultralight and quick-to-setup growing volume. Many possible layouts here, so the design is intentionally "unopinionated" on other decisions such as fully artificial vs some natural light, regolith vs water shield, material selection, and even inflatable vs rigid (both have advantages, but imo inflatable will have a lower overall cost for at least the early missions, and probably long after).

Equipment and furnishings can have lightweight tensile secondary structures and be mounted to load rated break-safe loops in the ceiling, walls, and floor. These include internal fabric partitions, equipment racks, lights/electrical/plumbing, stowage sacks, lay-flat hammocks (~1kg for a bed/chair), and cable-supported NFT hydroponics ala UA's M/LGH. Some interior components might be pre-installed on Earth, saving labor on early missions. Operational constraints should be in place to avoid overloading and excessive floor deflection for non-rigid designs.

I'm sure I'm missing a lot, but a few of the more obvious problems/challenges include:

Walking on a fabric pressure vessel under tension? Yikes! But I think it can be made ok if covered with a suitable load-spreading foam "carpet underlayment" and an appropriate thin hard-wearing traction floor — picture a souped-up vinyl carpet protector, though perhaps not actual vinyl. Or instead of foam, perhaps alternating-direction layers of coroplast (or per the low-tech survival thread, cardboard) to spread out point loads.  Whatever the floor protection layer[​s] ends up looking like, it's almost certainly lighter/cheaper/less work than building a complete standalone structural floor and supporting wall/column structures (which is effectively what is replaced).

It still needs a lightweight structure to support the radiation shield and floors if pressure is lost. This feature reduces loss of equipment, but not necessarily loss of life. One possible design has internally-supported roof trusses, another resembles a suspension bridge with external towers. IMO long-term this won't actually be necessary once high pressure reliability is demonstrated (similar to Starship omitting the "necessary" LES), but it's needed for early buildings.

There are complex seams at the intersections. Probably early designs will be conventional sewn seams doubled with reinforcing straps. One possible solution is multi-way buckles, which might allow individual segments to be replaced without sewing (partly mitigating the floor wear risk). Heat welded bladders (similar to Transhab) could re-seal compartments to meet leaktightness and redundancy requirements specific to each structure.

Expansion and contraction with temperature and pressure can cause structural fatigue and abrasion. In extreme cases the entire structure could "walk" with each cycle. I assume that suitable materials, structural margins, anti-scuff layers, guy wires, thermal/pressure regulation systems, and maintenance schedules can solve this.

Vibration and cyclic loading due to people walking and equipment operating is much smaller amplitude than pressure cycling, but higher frequency. Watch for resonance and fatigue limits. Structural margins and de-tuning/damping the building's resonance at walking frequencies should fix this, but in the worst case steel or titanium can be used for high cycle load parts.

To move between sealed compartments I envision pre-fab frames that attach to the wall straps, with a pressure-sealing door. Each side is an I-beam to transmit load around the opening. Smaller hatches allow maintenance access.

How to wire/plumb between pressure-isolated compartments? My idea is to route these between the weave of the pressure restraining straps (making a hole in the air bladder lamination layer), with a sealing plate over the opening from both sides. Internal partitions are contingency air bladders only, so acceptable leak rates may be relatively high.

Any pure tensile wall/ceiling/floor will shift in response to pressure changes in adjacent compartments. This could pose a problem for material strain rates, causing secondary liner damage, or directly causing injury to occupants. Still better than instant depressurization, and again I think the ultimate solution is "don't depressurize the adjacent compartment," but additional work is needed to mitigate this risk. The obvious solution is to replace the pure tensile webbing with foam-core composite panels with enough profile thickness to resist the bending moment, but this carries a significant design penalty.

Sound transmission between rooms could diminish privacy. I assume additional acoustic layers would be used for private areas if needed (suites, bedrooms, private offices, etc). Also equipment and ventilation will provide noise.

Variations

Naturally this design can be imported from Earth and/or made on Mars. Possible tensile materials include carbon fiber, kevlar, basalt fiber, glass fiber, steel, or UHMWPE.

The same geometry can be made self-supporting rigid structure by rotating the "waffle" to a top-down view. The outer hoops are rigidized like grain silos, and the inner rooms have diagonal bracing.

If large open spaces are needed, the tensile walls can be replaced with a grid of I-beams or cables, with flat trusses at the outer walls to spread load between spans. Using I-beam verticals can yield a self-supporting regolith shielded design.

Anyway this post is already much longer than intended, so I'll leave further discussion of thermal, airlocks, deployment, operation, design evolution, and optimizations for another post. So please kindly rip this design to shreds let me know what I've overlooked. ;)

The volume filling polyhedra are intended as an alternate imprementation of that concept.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/03/2019 02:11 am
Space filling polyhedra were brought up a while back, eg https://forum.nasaspaceflight.com/index.php?topic=41427.msg1614790#msg1614790
The original concept for cubic structures with outer restraining hoops was way back in this thread:
[...]

No, the original was K-zero's, going back a couple of years, not a couple of weeks. (Edit: And repeated almost exactly one year later. We're actually running late, we should have been repeating this subject last November if we want to be consistent.)



Re: Rhombic dodecahedrons

That was also discussed earlier, although I can't find the pages. [Edit: November 2017 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1753122#msg1753122).] Lamontagne even did a sketchup.

If you arrange them with a single point down, a nice thing is that eight vertices form a cube with a flat face parallel to the ground (as illustrated in the following animation.) Square rooms, use the gaps in-between for utilities, stairs, corridors, etc. Say three story cubes, hallways between rhombs opening from the second floor, utilities at one and three, stairs between rhombs on the edges, internal stairs inside the cube.

(https://upload.wikimedia.org/wikipedia/commons/9/90/Cubes-R1_ani.gif) (https://upload.wikimedia.org/wikipedia/commons/9/90/Cubes-R1_ani.gif)

The good thing (structurally) is that the rhombic dodec is closer to a sphere, therefore the forces flow around the vertices and edges nicely. The bad thing is that you can't tessellate larger and smaller rhombic dodecs together. With cubes you can. So with cubes, you can start with smaller cubes, join on larger ones as your building capability improves. (Or add small cubes to the outside, while gutting the inside into larger cubes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/03/2019 03:05 am
Has this been posted? The next round of NASA's 3D-Printed Habitat Competition winners have been announced:
https://www.nasa.gov/directorates/spacetech/centennial_challenges/3DPHab/latest-updates-from-nasa-on-3d-printed-habitat-competition (https://www.nasa.gov/directorates/spacetech/centennial_challenges/3DPHab/latest-updates-from-nasa-on-3d-printed-habitat-competition)

First place in this round:

https://www.youtube.com/watch?v=W4pxp5AGeNE (https://www.youtube.com/watch?v=W4pxp5AGeNE)

Next round is a print-off between the teams. $2m prize pool.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/03/2019 06:12 am
Whoah, that's a cool design. Bowing the pressure surface inward so that it's compressive. Clever idea, using a hyperboloid structure loaded with the water tank on top.

Some interesting takeaways from their video:

The non-water tank radiation shielding is primarily HDPE, presumably of ISRU origin. This means the radiation walls don't have to be a couple of metres thick to get a significant shielding bonus. The HDPE walls seem to be around 50cm thick. HDPE internals also cut the radiation dose further. Piping is also printed.
The windows are ISRU polycarbonate. It seems these guys think plastics would be fairly easy to make on Mars.
Construction time is estimated at 60 days.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/03/2019 02:33 pm
This has been bugging me for a while, so I sat down and actually worked out the relative sectors that each angle of elevation contributes to a hemisphere, and added cosine through the Martian atmosphere for the midpoint.

  0-10: 5.19: 1.09: 17.3%  (231.8g/cm^2)
10-20: 4.13: 1.06: 16.8%  (78.40/cm^2)
20-30: 3.14: 1.01: 16.0%  (47.8g/cm^2)
30-40: 2.24: 0.90: 14.2%  (35.2g/cm^2)
40-50: 1.47: 0.77: 12.2%  (28.5g/cm^2)
50-60: 0.84: 0.63: 10.0%  (24.7g/cm^2)
60-70: 0.38: 0.46:   7.0%  (22.3g/cm^2)
70-80: 0.10: 0.28:   4.4%  (20.9g/cm^2)
80-90: 0.00: 0.10:   1.6%  (20.3g/cm^2)

Numbers don't to 100% add due to rounding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/04/2019 02:45 am
Going back to radiation shielding materials, OLTARIS tells me that a 2m thick dome (well, sphere) on Mars reduces the radiation dosage inside to about 1/4 of the unshielded surface dose. So that's 20g/cm^2 of CO2, 200g/cm^2 of H2O and the surface blocking half the incident GCR is 300cm of regolith (this is modeled for backscatter).

Next I'll try with 200g/cm^2 of Martian regolith and then try a mix of 100g/cm^2 ice then 100g/cm^2 regolith to see what that does.

How does the 2m thick sphere compare with my 3.62m thick infinite horizontal slab? 2m infinite slab? In general what thickness of slab provides equivalent shielding to a 2m sphere?

My geometric intuition says it's <3.62m, which would imply that large flat slabs, not hemispheres, are the optimal shape for city-size radiation shields.

Is it possible to tell the software to do an infinite flat slab approximation? Or is it possible to model a "flattened cube" aka rectangular prism 100x longer and wider than it is tall (probing levels in the center not the edge)? That would help settle this question of whether a grid of spheres vs. a grid of cubes-with-hats is a more mass-optimal geometry for city-size shields, and unfortunately I don't have access to OLTARIS to do the calculation myself. Pretty please Lampyridae? :-[... :)

I'm afraid I cannot "settle" a question. OLTARIS is code, effective dose of cosmic radiation is still very lacking in understanding and we're not even sure how much radiation can be considered bad.

I agree with the caveats you mention, but nevertheless I think we can still establish the optimum geometry. Just choose your favorite shield material and scale the thickness based on whatever the acceptable dose winds up being. We don't know yet if 2 meters or 4 meters of regolith is necessary, but we should be capable of establishing whether hemispheres or wide slabs are better geometrically.

What I can safely say is that the first criteria will be safety, followed by relative cost and ease of manufacture - these two are closely correlated. Inflatable structures are currently more expensive than the traditional aluminium tin cans, because they have multiple layers and require stitching. I'm not making this up, this is according to NASA and ILC Dover.

Great, thank you! This is exactly the kind of high-level info that's needed to constrain the design. Do you know how roughly much more expensive? Two times? Ten times? More?

Of course rigid habs require assembly on the surface, which is more expensive. We want to optimize the total manufacturing cost + assembly cost. This is why I suspect inflatable habs may find their niche in early missions, as well as temporary outposts that can accept higher material cost in exchange for ease-of-transport and rapid setup requiring minimal labor/equipment.

I would also wonder about the relative mass efficiency. ILC Dover was working on in-space designs iirc, which require many layers for MMOD shielding. And tensile materials have some of the highest strength-to-weight ratios, but the efficiency goes down when embedded in polymer to make rigid parts (eg CF to CFRP).

OLTARIS treats everything as a sphere with thicknesses, as an XML format. There's a CAD importer to work these things out but I've yet to figure it out.

I could have sworn I saw a mention of defining "slabs or spheres" somewhere in the OLTARIS publications, but I can't find it right now. I'll keep looking.

I can try and model a slab of loose regolith, but that means you have incorporated structure sufficiently strong enough to hold the slab off the ground as a tray, perhaps steel girders and thick steel plate on the sides. Or, some pantheon-like structure made with Martian bricks (as easy as packing into a rubber mould and hitting with a hammer - FeO acts as a binding agent).

Again, under normal loads the roof will still be trying to fly off due to internal pressure. The building already needs to be sufficiently strong to hold this.

I did mention this in my first post:

Here's my humble attempt at a first principles approach. Rather than start with a desired shape and work backward, I'll start with a mass-efficient pressure vessel and work forward. Something more than the standard tuna can.

Imo this approach is justified because pressure restraint is by far the largest structural load (including holding an n meter thick regolith shield overhead), and most ISRU-derived structural materials will be expensive and should still be conserved as much as reasonably possible. Mining and processing on Mars is costly, even if it's cheaper than Earth imports. Ultimately it's about minimizing total lifecycle cost per square/cubic meter per year — energy, water, labor, imports, etc.

[snip]

It still needs a lightweight structure to support the radiation shield and floors if pressure is lost. This feature reduces loss of equipment, but not necessarily loss of life. One possible design has internally-supported roof trusses, another resembles a suspension bridge with external towers. IMO long-term this won't actually be necessary once high pressure reliability is demonstrated (similar to Starship omitting the "necessary" LES), but it's needed for early buildings.

and later elaborated:

For habitats on Mars I think it is highly undesirable that their structural integrity would be dependent on pressurization. Musk has said that he doesn't want Starships that only maintain their physical integrity when pressurized.

You may need to deal with depressurization emergencies on Mars. As you don you pressure suit to deal with such problems you don't want the ceilings and walls of your habitat to cave in at the same time.

As mentioned in my inaugural post, I agree. But the desirability (and the design penalty you should 'rationally' be willing to pay) gets smaller the more reliable the pressure maintainance gets. Leak-before-burst is common, so pressure monitoring gives you early warning. And a large hab takes a long time to depressurize, so you can slap a super sticky repair kit on it. If it's quick to depressurize, you're dead anyway. So I'm not totally convinced that this so-called-requirement is actually a necessity.

Not sure about the Starship analogy. Starship can only maintain its physical integrity during flight when pressurized, so clearly Musk doesn't consider this a hard-and-fast rule. Afaik the only reason Musk did that is for ease of handling in the factory so it doesn't wrinkle the metal, but the process of manufacturing an inflatable pressure vessel has no such issue from accidentally handling unpressurized components. These inflatable habs are initially built on Earth of course.

My favored solution is just installing columns at the perimeter (outside the pressure vessel) and using a "3D suspension bridge" to hold up the rad shield. The cables would go through the regolith so they probably need a protective jacket, but that's not so heavy. Guy wires and rock anchors would handle side loads. These columns might be made from imported stacked CFRP cones, marsteel tubes, tensile wrapped marscrete, interlocking compressed regolith block, or some other suitable material.

For a rigid cellular hab I think you probably just make the grid of vertical steel columns do double-duty as both tensile "cables" when pressurized and compressive columns when unpressurized. Also each column needs a marscrete footer to transfer weight to the ground. The whole hab can float off the ground and achieve very small thermal transfer, which is a Good Thing™ for not melting the underlying permafrost.

If you mean loose regolith piled on top, it will most definitely not be a slab. The material will fill the divisions between each hot dog, and be thinner on top. The regolith will sit at the normal angle of repose, which is about 30 degrees on Mars. It will only start from the top of the outer hot dog arch. For a regolith depth of about 2m you will only get the inner hot dog fully covered by regolith. However, there as indicated previously, there will be sections of thick vertical coverage as the soil fills the cracks. You can eliminate this by the use of simple lightweight sheeting (see my soil arching discussions)

Whether you call the shape a "slab" is pure semantics of course. First someone thought all slabs must be rigid, now someone thought all slabs must be perfect rectangular prisms. Damn, this word is only confusing people! Anyone have suggestions for replacement terminology? All I meant by the word "slab" was a shape that's long/wide and short.

I do love it when people work this out the solutions for themselves. A lightweight tensile catenary net is exactly my notional solution to the described problem, to minimize shielding mass non-uniformity.


Also for hoops the optimal "takeoff angle" isn't vertical, but the minimum restraint mass is achieved at an angle of roughly 22 degrees from the zenith for anisotropic material eg wound fibers (and...  prepare for incoming flame war :D). This minimizes the mass of the pressure restraint only, but the optimal angle to minimize total roof mass could be higher still due to the added per-area mass of any other layers.

but why? You are reducing shielding.

...snapping defeat from the jaws of victory. :'(

You are only "reducing shielding" in the very limited sense of removing it from where it would otherwise be suboptimally too thick, and this is a good thing not a bad thing. Uniformity maximizes the total per-kg shielding, because if it were non-uniform then more extra radiation radiation would "leak through" the thin places than the extra radiation stopped by the thick places. A completely uniform slab is the theoretically optimum shape, though naturally some non-zero deviation from perfect optimality can be accepted. In other words, it doesn't have to be perfect. ;)

Obviously (and this should go without saying, but I'll say it anyway) if you believe that the fully-qualified extra regolith emplacement cost will turn out to be cheaper than adding a tensile net, just do that instead.


If the hot dog pack deflates, the loose regolith will be an unmitigated disaster. Remember that soil doesn't sit, it transmits forces, so even inflated connector tunnels can get crushed if the regolith piles on it wrong. This is why there is so much interest in building solid structures as opposed to simply burying them in dirt. So, a solid slab is the way to go.

Yes I mentioned this consideration before, along with a myriad of available solutions, so I won't be boring again and rehash it all over (I'll find the quotes on request). Suffice it to say I disagree with your conclusion that it's never allowable. However even if we assume that you are correct, there still exist many possible mitigations, only one of which (and the most expensive of which imo) is "replace the entire mass of cheap piled regolith with expensive Marscrete."

Look at gravity embankment dams: big heavy ubiquitous cost-optimized structures. They're almost entirely made out of dirt and not huge solid blocks of concrete. Only a relatively thin layer of concrete is used to protect the surface from weathering, but on dessicated Mars even the top concrete layer can be omitted. The same sort of cost optimization strategies will be employed on Mars, though obviously the details will vary.

[picture]

I suppose what you've depicted is one possibility in the solution space I'm describing, but it's a pretty poor choice imo. The clear disadvantage is that it has the geometric shielding downside you've annotated.

This is a perfect illustration of why I prefer wide aspect-ratio habs (it minimizes perimeter-per-area), and why I took the time outlining several available options for shielding the perimeter: A) a cable restrained "above-ground pool structure" for the slab edge, so it needn't slope at the angle of repose, B) hanging sandbags at the wall edge to make a cheap vertical wall using less material than a gravity bank, C) a gravity bank, and D) place buildings next to each-other, connect a hanging tensile fabric net in between, and extend the shield continuously from one building to the next.

By combining A+B+D you can have a structure with both sufficient shielding from Day 1 at the cost of filling sandbags, and an inexpensive path for expandability as needed — the cheaper loose regolith covering scales as footprint while more expensive sandbags scale as perimeter, so as the colony footprint expand the costs scale better and better. Or if you prefer gravity banks over sandbags for a particular building, choose A+C+D. Easy. You can even combine A+B+C+D in a single building.

You've noted the height difference as 1.9 meters vs 3.85 meters, presumably to show how the regolith falls into the cracks. But 1) I assume a tensile net like you described yourself, and 2) given those dimensions the amount of material that falls into the cracks only increases the mass/cost by ~27%, not the 103% difference in height indicated. Plus all that shielding mass is not entirely wasted, just suboptimally used, so the cost difference to achieve equivalent shielding is even smaller.


I wonder if there's a better design than vertical rectangles. I know you've talked about using hexagons, but that doesn't tessellate in 3D well without hexagonal prisims.

What about an octagon/square tessellated grid, with vertical layers alternating octagon and square? I'm away from any kind of modeling program to show what I mean, but basically each cell is a square at the bottom, an octagon at the waist (side length of square and octagon remain the same) and closes to a square at the top. Four  cells are attached to it at the same level, at the "corner" edges of the octagon, and 4 are attached half a level up and 4 half level down, their square base/top attached to where the octagon waist's form a square.

quick MS paint- Top-down view of a single cell.
The triangle shapes on the corners are connections to same-level cells. (to properly tessellate, this requires a cutout in the top and bottom of the hab, but I don't think it affects much) The rectangles on the orthogonal sides are hatches+stairs between habs that are half-level displaced.

Overall, this approach produces more spherical habitations that still "soap bubble" together with flat walls. Vertical collums at the corners of the base can reinforce the structure vertically against the forces of pressure loss.

Edit: After further consideration, there are tetrahedral voids at the corners, exactly where the cutouts need to be for same level hatches. Stacked airlocks between cells should fill the void. (Hab 2 is a single level of habs, dark grey is outside/where half-level habs would fit. light grey is the  slope from octagon to square, with airlocks connecting habs- this area forms a void in a multilevel structure, but a larger airlock could fill the void with cubes)

There are many possible shapes that will tessellate in 3D. This one looks cool, but I'm struggling to find any sort of practical advantage over rectangular prisms that can't be achieved in some other, cheaper way. Can anyone find one?

In fact, sadly all I really see is downsides here. It's not an advantage that it's a more "sphere-y" shape, because on the outer edge it's less structurally optimal than pure-tensile hoops or pillowing, and on the inner volume it introduces unnecessary walls and structural bending loads compared to a simple rectangular grid. For rigid internal emergency pressure walls, instead you can just making each tensile wall a foam-core panel to resist bending and waste less internal volume overall. And full airlocks inside are overkill imo, all you need is emergency pressure doors (it appears you may be designing backwards here, letting overall end shape define functional needs rather than the other way around).

And that's not to mention all the problems associated with non-rectilinear interior layouts. Just ask anyone who's lived in a geodesic dome.

I've wondered about non-rectangular cells myself, but thinking it over revealed far more downsides (mass, cost, and human factors) than potential upsides. It's different, but I won't declare that it's "better" until there's a cogent argument for why it's actually better. On the contrary from where I sit it's structurally weaker/heavier and makes awkward-shaped rooms, neither of which are good attributes for a Mars hab.


But a two-floor hexarhombic sounds quite doable, and scales nicely whilst having a useable individual unit size.

Yet any 3-space tesselation will scale just as "nicely," including rectangles. And the obvious choice of one-floor-per-cell has arguably even more "useable individual unit size" than two-floors-per-cell. The floors can be any height, so eg tall factory space can still be implemented as one-floor-per-cell without any penalty.

This idea introduces an internal structural (but non-pressure-restraining) floor that would otherwise be unnecessary, but the cells boundaries still need to be exactly as massive because they're now twice as tall. So choosing one-floor-per-cell adds a structural floor introducing extra mass, without that decision removing mass from anywhere else in the design. Not a good choice imo.

Stacking funny-shaped non-rectangular blocks is perhaps "amazing," and I wouldn't advocate stopping any conversation. But I will point out that I see no practical advantage in building a "martian habitat" in this way over using rectangles (these words are also in the thread title, so this is still on-topic).


Space filling polyhedra were brought up a while back, eg https://forum.nasaspaceflight.com/index.php?topic=41427.msg1614790#msg1614790

https://en.wikipedia.org/wiki/Category:Space-filling_polyhedra

Yes, exactly. I read those posts excitedly hoping that any moment someone would "snipe" these ideas from my head (which I thought were obvious) and save me the trouble of writing them down, but sadly the topic faded away. That's what motivated my first post: attempting to rekindle analysis and discussion down what seemed to be an extremely fruitful design avenue. This has succeeded beyond my wildest expectations, so thanks everyone!


One question I had at the time was, how hard is it to design a panel that can hold pressure from both sides? That implies a sort of flexible material that can change the direction it bulges in.

That, or some structure strong enough to resist the bending (which will be heavier of course, but rigidity has other benefits that might outweigh this cost).

I think for a rigid hab you probably just have the tensile walls constructed as foam-core composite panels. This has the added advantage of doubling as some "free" insulation and soundproofing between rooms, which can sometimes delete mass from other building systems.

Is that the goal here, or is it just flexible modular volumes without internal panels, just the struts?

I don't think we know yet, and I don't think the answer will be the same for every building on Mars. Just like buildings on Earth are not all identical (in either appearance or construction), so too on Mars. There's no single "best" approach.

Even with rigid tensile walls, I am assuming that the edges/corners will be strengthened and will take a disproportionate amount (but not most) of the load. This form optimizes structural economy, for reasons which may or may not be obvious.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/04/2019 12:12 pm
Some simple expansions of the hexagonal structure.
An interesting result is that the vault at each floor can serve as a pressure vessel, as long as there are not too many utility holes in it !  So extra points for safety.
As a set, everything  is a multiple of 2.5m.  Floor are 5m high, interfloors 2.5m.The hexagons are 5m to the side and 10m in diameter (didn't know that property of hexagons!  Neat)
Although the columns spaces are hexagonal, there is no reason a rectangular array of walls could not be used inside, for living quarters of optimal squareiness. :-)
The interfloor can be packed with light concrete for additional radiation protection.
The columns have a nice oriental gazebo look, IMHO.
I don't think we really need to go higher than 2 floors.  A few square km of this could house a ridiculous number of people.  Could be arranged overall in interesting shapes, doesn't have to be rectangles.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/04/2019 12:25 pm
BTW a 5 m floor subdives nicely into two 2.4m floors for packing in the spaces with living areas.  So 2.5 m for private spaces, 5m for commercial and meeting space and 10m for larger public spaces, parks, etc.

Large spaces without columns for sports and activities of that nature could have large cathedral type vaults, with corresponding stronger columns.

The Mezquita of Cordoba is another fine example of this, with the larger cathedral built into the mosque pattern.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/04/2019 01:06 pm
Well, now. It looks like regolith is even worse than I suspected. You can see regolith "helping" like the monkey in Cloudy With a Chance of Meatballs. Unless it's more than 70cm thick, it actually increases radiation dosage slightly, and offer no protection at all until it's over 1m thick. It needs to be over 2m thick before it offers anything like modest protection. This means that unless there is complete coverage, part of the regolith is wasted and some is actually detrimental.

A layer of alternating water and regolith seems to work reasonably well, although  It does have an overall synergistic effect though.

Indicative results only - radiation as calculated at a point at 1AU in free space protected by sphere of 40g/cc Mars atmo and then 500g/cc of whatever material. Halve it to get (very!) approximate Mars equivalent dose rates.

500g/cc H2O: 0.14mSv/day
500g/cc regolith: 0.37mSv/day
500g/cc H2O/regolith: 0.2mSv/day (call it <0.1 on Mars)

I wonder if a 20/20 layering of regolith and water will work better. Most high-Z materials start their neutron cascade tantrum at around 20g/cc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 04/04/2019 01:27 pm
Would there be any benefit to using an "icecrete" mix of water and regolith, rather than separate layers?  The ice would stabilize the regolith, meaning that you might not have to worry so much about it structurally, and could make things like slabs (presumably as long as they were insulated on the outside to prevent occasional above-zero warming).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/04/2019 01:38 pm
Would there be any benefit to using an "icecrete" mix of water and regolith, rather than separate layers?  The ice would stabilize the regolith, meaning that you might not have to worry so much about it structurally, and could make things like slabs (presumably as long as they were insulated on the outside to prevent occasional above-zero warming).

Possibly... when I made the layer thickness 20/20 (20cm water, 12cm regolith) it upped the protection to 0.18mSv/day. Structurally, regolith/ice mixes are very strong. NASA ISRU basically binned the idea of digging for high water-ice content regolith because it was too difficult to extract it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/04/2019 05:16 pm
Or how about a thickish layer of regolith and then a thickish layer of water ice? Seems that regolith seems to make matters worse initially, so push it in front then use the water ice behind to absorb the secondary radiation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/04/2019 10:18 pm
A  very simple spreadsheet of the 5m hexagonal cell design.

The walls are about 6mm thick of  standard construction steel A36 grade.
The six columns are 300x300 by 12mm wall each, design depends on tension load.
The overall mass of a cell with no walls is 10 Earth tonnes
The overall mass of a fully enclosed cell is 17 tonnes

The cost of transportation at 500 $ per kg is about 9 million dollars
The bare cost of the steel on Earth is about 9000$ (no assembly, flat plate)
The cost of Mars produced steel is about 200 000$ (some forming, no assembly)

For 5m of regolith on top the tension to compression ratio is 1.6.  So the structure is in tension.

To be taken with a healthy grain of salt :-)
Iy you feel like checking the numbers it would be much appreciated!

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/04/2019 11:06 pm
Lampyridae,

Or how about a thickish layer of regolith and then a thickish layer of water ice? Seems that regolith seems to make matters worse initially, so push it in front then use the water ice behind to absorb the secondary radiation.

Was going to ask the same thing.

Can we see a thick regolith over thick water vs thick water over thick regolith comparison?



Edit: Just realised that your "depth" is in g/cm². In other words, density*depth. Since regolith has perhaps twice the density, it's actual depth will be half the equivalent g/cm² as water.

Therefore, can you do the same-scale test that you show in the final graph? Is the graph meaningful?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 04/05/2019 03:30 am
A  very simple spreadsheet of the 5m hexagonal cell design.

The walls are about 6mm thick of  standard construction steel A36 grade.
The six columns are 300x300 by 12mm wall each, design depends on tension load.
The overall mass of a cell with no walls is 10 Earth tonnes
The overall mass of a fully enclosed cell is 17 tonnes

The cost of transportation at 500 $ per kg is about 9 million dollars
The bare cost of the steel on Earth is about 9000$ (no assembly, flat plate)
The cost of Mars produced steel is about 200 000$ (some forming, no assembly)

For 5m of regolith on top the tension to compression ratio is 1.6.  So the structure is in tension.

To be taken with a healthy grain of salt :-)
Iy you feel like checking the numbers it would be much appreciated!

Interesting. How easy would it be to assemble these?
Even on Mars, you could mass produce the walls and columns, probably from the soil you moved.
Are larger cells more mass efficient? I found that making the diameter larger for my silos allowed for a greater encompassed volume proportionally. Square area, cube volume and all that. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/05/2019 11:59 am
A  very simple spreadsheet of the 5m hexagonal cell design.

The walls are about 6mm thick of  standard construction steel A36 grade.
The six columns are 300x300 by 12mm wall each, design depends on tension load.
The overall mass of a cell with no walls is 10 Earth tonnes
The overall mass of a fully enclosed cell is 17 tonnes

The cost of transportation at 500 $ per kg is about 9 million dollars
The bare cost of the steel on Earth is about 9000$ (no assembly, flat plate)
The cost of Mars produced steel is about 200 000$ (some forming, no assembly)

For 5m of regolith on top the tension to compression ratio is 1.6.  So the structure is in tension.

To be taken with a healthy grain of salt :-)
Iy you feel like checking the numbers it would be much appreciated!

Interesting. How easy would it be to assemble these?
Even on Mars, you could mass produce the walls and columns, probably from the soil you moved.
Are larger cells more mass efficient? I found that making the diameter larger for my silos allowed for a greater encompassed volume proportionally. Square area, cube volume and all that.
Leaks are an issue.  There are a lot of joints and these translate as leakage points, and air on Mars is fairly expensive and hard to come by.  Overall mass goes up to the cube of the gain in diameter, so eventually the strain from the structural mass will grow higher than the strain from internal pressure.  There is also the size of the individual structural members that become hard to manipulate and manufacture.  So my guess is not much bigger, perhaps a bit smaller.  you can build much bigger, but not for cost saving reasons, rather for some specific requirements, such as a stadium.
BTW there was a conceptual error from my part in the design of the columns that are used in the external walls.  These are different from the internal columns since they also have a very high side load coming from the hoop stress from the exterior walls, so they would need to be reinforced significantly.  So perhaps one more tonne of steel per external module for that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 04/05/2019 12:05 pm
Or go with flying buttresses to stay with the Cordoba Mezquita/ecclesiastical buildings theme.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/05/2019 12:34 pm
Cells gone wild!  Divorcing the wall pressure system from the roof hold down system.

Unfortunately probably a poor configuration for radiation protection.  :-(

External walls removed to show structure (just in case I get the question)
I guess this pretty much answer's Rocket Surgeon's suggestion :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/05/2019 02:58 pm
Lampyridae,

Or how about a thickish layer of regolith and then a thickish layer of water ice? Seems that regolith seems to make matters worse initially, so push it in front then use the water ice behind to absorb the secondary radiation.

Was going to ask the same thing.

Can we see a thick regolith over thick water vs thick water over thick regolith comparison?



Edit: Just realised that your "depth" is in g/cm². In other words, density*depth. Since regolith has perhaps twice the density, it's actual depth will be half the equivalent g/cm² as water.

Therefore, can you do the same-scale test that you show in the final graph? Is the graph meaningful?

Looking at the curves I have, the 50g/50g/cc blocks ice/regolith worked out worse than 20/20, so having hydrogens as close as possible to source seems like it really helps, as in a regolith-ice mixture. I don't have time today to run the bulk shield configurations (half ice, half regolith), but I'll do that maybe next week.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/05/2019 05:41 pm
Unfortunately probably a poor configuration for radiation protection.  :-(

This can be fixed if you just take the center section (with shielding on top) and tile it horizontally to the desired size. Then place walls (optimally slightly thinner) around the edge.

Eventually it becomes a large wide building. Picture a warehouse except bigger: 10 to X stories tall. A city-building. At this size the radiation shielding on top becomes a tiny fraction of the cost (because it shields many floors), and so does the radiation shielding on the side (because the area-to-perimeter ratio is so high). These huge structures would naturally come at later stages of colonization.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 04/05/2019 09:56 pm
Cells gone wild!  Divorcing the wall pressure system from the roof hold down system.

External walls removed to show structure (just in case I get the question)
I guess this pretty much answer's Rocket Surgeon's suggestion :-)
I have some really clear images in my head about this from earlier. Maybe there a discussion about the issues of atriums? The cellular structure can fill any volume but beware of pressurised atriums. Small spaces may be within margins but even then stresses are no longer trivially in balance.

The solution in my head was that the atriums were reenforced with wide bands of cable, similar to the sort of engineering you do for spanning bridges I suppose, but now to conserve a cylinder instead of a linear platform. This still keeps the modular aspect because the only customisation you are doing insitu is cutting cable to varying lengths.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/08/2019 12:48 am
Good point. In fact any size or layout atrium (up to and including the entire volume) can be architected if cables are run in all three axes.

The cable spacing can be chosen based on building needs like accommodating large equipment etc. And all the same "menu items" are available, like choosing posts and guy wires to yield a design that's supported when unpressurized. In my view all these are just different implementations of the same cellular concept, each with its own pros and cons.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/08/2019 02:20 am
I generally make an assumption when talking about metal framing in this context, but since people are occasionally doing the actual calculations, I thought I'd ask...

Obviously you can create a purely flexible tensile structure. But if you are using metal (steel/aluminium) and assume a gauge-thickness sufficient for a rigid shell or frame to support 10t/m² tensile pressure, is it self-supporting when unpressurised? And is there a good/consistent rule of thumb for what kind of tonnes-per-square-metre compressive load (of additional shielding-mass) it could support for ten tonnes-per-square-metre tensile load.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 04/10/2019 12:22 am
Considering the often mentioned problem of containing a liveable pressure inside a non spherical / cylindrical
vessel, has anyone looked at using multiple layers of relatively low pressure differentials ?


Say five layers with a 2.5 psi increase as you progress through several locks into the central habitat volume which has 12.5 psi at 30% O2.  Would this work with a dome on a rigid floor as there would be only 2.5 psi pressure
on any joint ?  Airlocks and windows could be rigid units extending through all the layers or individual doors in each separate wall.  Pro's and con's for each.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/10/2019 06:16 am
Considering the often mentioned problem of containing a liveable pressure inside a non spherical / cylindrical
vessel,

Buy why would you want to use a non-spherica/cylindrical geometry? For any pressure vessel (cellular, nested, whatever) these shapes optimize the volume-per-weight.

Unlike monolithic pressure vessels, cellular pressure vessels need not be cylinders/spheres on the large whole-building scale. Just on the small cell scale, and only on the outer wall, and really more like "quilting" or "pouching."

has anyone looked at using multiple layers of relatively low pressure differentials ?


Say five layers with a 2.5 psi increase as you progress through several locks into the central habitat volume which has 12.5 psi at 30% O2.  Would this work with a dome on a rigid floor as there would be only 2.5 psi pressure
on any joint ?  Airlocks and windows could be rigid units extending through all the layers.

Good thought, but sadly pressure vessel scaling means the overall mass will be the same as using a single wall (actually slightly higher, because the thicker wall increases volume a bit). So there's no gain to using this technique, but it introduces extra manufacturing complexity, extra air mass, extra surface area to fail (and maybe inspect), and an extra 4x safety-critical pressure regulation systems. Any wiring or other penetration will need 5 times as many redundant seals. Thicker walls also tend to be heavier because any components running through the wall, including parts of the wall assembly itself, will gain length and therefore mass. Sure you could make the layers really close together, but then why not simplify it down to a single (possibly multiply-redundant) wall?



Random thought: if a redundant double/triple wall has a vacuum pulled inside for leak detection, this might also allow any (precious!) leaking air to be recycled using a vacuum pump.  Any hole in the external wall would leak into the wall cavity, so in theory this design can achieve ~zero net through-wall air loss despite the inevitable presence of tiny leaks. Due to the pressure differentials the leaked gas would be mostly internal air, so it's likely worthwhile to send it to the chemical plant for reclamation, or maybe just pump it into a small plant room. Either way the system could detect new leaks (by monitoring dP/dt) and separately discriminate between internal and external leakage flows (by analyzing gas composition).

This leak detection and air recycling technique should also work using a less massive ME-MLI anti-crush structure instead of a full-pressure double wall. The vacuum pump means the ME-MLI anti-crush layer can tolerate small leaks without becoming thermally ineffective, And if you flood the cavity with CO2 you can "switch off" the insulation, good for rejecting waste heat or exploiting solar/diurnal gain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/10/2019 09:36 am
12.5 psi at 30% O2.

Where did you pull those number from?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/10/2019 10:46 am
Considering the often mentioned problem of containing a liveable pressure inside a non spherical / cylindrical
vessel, has anyone looked at using multiple layers of relatively low pressure differentials ?


Say five layers with a 2.5 psi increase as you progress through several locks into the central habitat volume which has 12.5 psi at 30% O2.  Would this work with a dome on a rigid floor as there would be only 2.5 psi pressure
on any joint ?  Airlocks and windows could be rigid units extending through all the layers or individual doors in each separate wall.  Pro's and con's for each.


Effectively there are none. You appear to save a bit on mass but that's because your average pressure over the volume is decreased. There are applications for having low-pressure regions; eg transparent greenhouses and an "EVA ready" zone.

- Radiation shield required still the same (actually larger now due to increased volume from internal airlocks etc
- Greatly reduces interconnectedness and breaks up a large area into many small ones; claustrophobia and isolation
- For 2 sections, you are doubling the number of seals, pressure gauges, ultrasonic leak detectors, valves etc that must be imported from Earth. 3 sections, tripling, 4 sections, quadrupling etc.
- Introduces emergency corridors through the various pressure zones for evacuation
- Makes moving of large objects through the interior very difficult: limited by airlock size unless you pressurise the outer section
- Each pressure wall has to be rated to 1 bar (or 12.5 psi) anyway in case of inner wall failure, though with maybe a lower safety factor.
- Constant compression and decompression between layers introduces possibility of bends, hypoxia and altitude sickness if the pressure differential is at all great
- Sudden changes in humidity; opening the airlock into a lower pressure section creates a cloud of condensation
- Constant back-and-forth introduces large amounts of wear and tear on seals, vacuum pumps, requires additional power to rebalance pressures
- Reduces response time to emergencies - eg guy has embolism on the other side, you have to go through the airlock to get to him
- Emergency evacuation from one section to another is a nightmare
- 30% O2: fire bad. Also at 12.5psi is hyper oxygenation (25% O2 equivalent @ 15psi). Bad for long term health.

Generally, there is no reason not to have 1 bar of pressure at 80/20. You put your life in the hands of four rubber toroids rated for 2 bar+.

Building large pressure vessels is not hard. To give a relatable example, a 2 litre, 0.5mm thick PET bottle can take pressures of more than 5 bar. Mentally scale up radius and thickness to get a liveable-sized habitat. Obviously better materials than PTE can be thinner and hold pressure. I'm not sure how much pressure aluminium cans can take; they usually fail at the crimping seal but can handle a pressure differential of over 1 bar.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 04/10/2019 10:55 am
12.5 psi at 30% O2.

Where did you pull those number from?

Just plucked them out of thinner air.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/10/2019 03:45 pm
Looking at these shielding and construction issues, I've come to a couple of conclusions.

First off, ice is nice. Whilst it has to be quite thick if you want to do some serious shielding, for applications where you can afford it to be thinner, it won't become useless or a net radiation contributor.

Second, location location location. As seen in one of my previous posts, the band immediately above the horizon covers the most area but its atmospheric shielding effectiveness is little better than the shallow slice of atmosphere directly overhead. Ideally, you want most of your protection against the above-the-horizon band, and terrain will gave that to you, cutting out maybe 30% of radiation with a 30 degree slope all around (eg in a crater). Even being backed up against a hill can block 1/6 of the visible sky.

There is a hard limit of 200g/cc where most non Hydrogen-heavy materials simply don't offer anything (see regolith), or just make matters worse. The Martian atmosphere seems to contribute to that, and we also see a similar spike on Earth at an altitude where there is 200g/cc overhead. It means that regolith works "better" dealing with radiation coming in at a low angle.

Third, caternary arches are very cool. The first reason is that they are natural arches and therefore quite strong. You can build them out of mud. The second is that because the shape is angled upward, there is a significant cosine advantage when shielding from radiation that is directly overhead or at an angle. Think The Gherkin in London as a domed example (although it bulges out). Essentially, you can use the same amount of material and have it thinner where you want it (the sides) and thicker where it counts (the top) - without actually making it so thick that the ice or whatever you are using for shielding is effectively opaque. Plus it looks cool, so long as it doesn't look too much like The Gherkin. There are disadvantages to it, of course. It's not a regular cylindrical shape and increases the size of the pressure vessel relative to its surface area, it's not easy to improve protection by adding side berms etc.

(https://www.octatube.nl/2/entity-file/entity/projects/field/header_5/instance/168/download/0/projectitem/168-glazen-luchtbel-neptuna/photo-924-thumb_view.jpg)

The Greenhouse Neptuna in Sweden is a pretty cool kind of alternative geodesic dome design. It would make sense to have your thin, flat sections facing toward terrain features (I'm imagining a "C" shaped partially buried crater) and the sloped end facing the open horizon to get cosine shielding depth. Overhead, the cosine shielding depth is pretty uniform, unlike a regular hemispherical dome which gives better overhead shielding closest to the rim.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/10/2019 10:05 pm
Looking at these shielding and construction issues, I've come to a couple of conclusions.

First off, ice is nice. Whilst it has to be quite thick if you want to do some serious shielding, for applications where you can afford it to be thinner, it won't become useless or a net radiation contributor.

Why do you say "afford it to be thinner?" At this scale thickness is expensive (due to material cost), not thinness.

I don't see how regolith would ever "become useless." Why would anyone design a useless (or worse, futile) radiation shield? At the risk of stating the obvious, one starts with the radiation requirements and determines the material thickness from that, not the other way around.


Second, location location location. As seen in one of my previous posts, the band immediately above the horizon covers the most area but its atmospheric shielding effectiveness is little better than the shallow slice of atmosphere directly overhead. Ideally, you want most of your protection against the above-the-horizon band

Agreed, but don't confuse that statement for saying that most of your shielding thickness should be on the walls of a building not the roof (and I know you wouldn't Lampyridae, because you say exactly the opposite two paragraphs later). A wide flat roof is even better at absorbing that above-the-horizon band due to cosine gain. You just need to make the building wide enough that most areas are shadowed by the roof, not the walls.

There is a hard limit of 200g/cc where most non Hydrogen-heavy materials simply don't offer anything

Just to be clear, is that an upper limit or a lower limit?

 The Martian atmosphere seems to contribute to that, and we also see a similar spike on Earth at an altitude where there is 200g/cc overhead. It means that regolith works "better" dealing with radiation coming in at a low angle.

Third, caternary arches are very cool. The first reason is that they are natural arches and therefore quite strong.[/quote]

...in compression. But gravity loads aren't the big one, pressure loads are.

You can build [catenary arches] out of mud.

Earth arches don't work if they're hollowed out, but I suppose you refer to frozen mud?

The second is that because the shape is angled upward, there is a significant cosine advantage when shielding from radiation that is directly overhead or at an angle. Think The Gherkin in London as a domed example (although it bulges out). Essentially, you can use the same amount of material and have it thinner where you want it (the sides) and thicker where it counts (the top) - without actually making it so thick that the ice or whatever you are using for shielding is effectively opaque. Plus it looks cool, so long as it doesn't look too much like The Gherkin. There are disadvantages to it, of course. It's not a regular cylindrical shape and increases the size of the pressure vessel relative to its surface area, it's not easy to improve protection by adding side berms etc.

(https://www.octatube.nl/2/entity-file/entity/projects/field/header_5/instance/168/download/0/projectitem/168-glazen-luchtbel-neptuna/photo-924-thumb_view.jpg)

The Greenhouse Neptuna in Sweden is a pretty cool kind of alternative geodesic dome design. It would make sense to have your thin, flat sections facing toward terrain features (I'm imagining a "C" shaped partially buried crater) and the sloped end facing the open horizon to get cosine shielding depth. Overhead, the cosine shielding depth is pretty uniform, unlike a regular hemispherical dome which gives better overhead shielding closest to the rim.

Definitely cool, but I have trouble seeing how it could possibly be more efficient than a wide slab geometry. If you take a wide slab building and "cut it like a cake," most pieces will only have shielding on top (efficient), with the side shielding provided "for free" by the roof shielding of neighboring slices.

edit: typos, formatting
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/11/2019 11:13 am
I lost my last post due to a timeout, so here's a brief summary. The Martian atmosphere and regolith can be treated as moderate-Z material, which adds dose reduction benefit until 50g/cm^2, then flattens out to 200g/cm2 before it gives any benefit again. (This is due to neutron production). The effects of regolith and atmosphere are cumulative. In other words, regolith shielding is less effective directly overhead and more effective towards the horizon.

  0-10: 5.19: 1.09: 17.3%  (231.8g/cm^2) - any regolith shielding here reduces dose
10-20: 4.13: 1.06: 16.8%  (78.40/cm^2) - 100-150g/cm2 shielding needed
20-30: 3.14: 1.01: 16.0%  (47.8g/cm^2)
30-40: 2.24: 0.90: 14.2%  (35.2g/cm^2)
40-50: 1.47: 0.77: 12.2%  (28.5g/cm^2)  - approx 180g/cm2 regolith shielding needed from here
50-60: 0.84: 0.63: 10.0%  (24.7g/cm^2)
60-70: 0.38: 0.46:   7.0%  (22.3g/cm^2)
70-80: 0.10: 0.28:   4.4%  (20.9g/cm^2)
80-90: 0.00: 0.10:   1.6%  (20.3g/cm^2)

High-hydrogen materials like water and polyethylene do not have this "minimum regolith" penalty to provide benefit. And since we're going to be dealing with hundreds of tonnes of water ice to fuel the return Starships anyway, there is no real penalty to using it as a shielding material. It is also quite strong in low temperatures, and can be made bubble-free to be transparent. In addition, it is an emergency water source.

My aim with exploring this design space is to make a large part of a shielded habitat able to have excellent dose reduction whilst affording a naturally-lit environment, much like the reasoning behind the Mars Ice House.

Below I attach a traditional hemispherical dome with regolith allotted according to incoming radiation. Note that top half is basically the same: 180g/cm2 of extra material are needed before the regolith shielding becomes effective again. At the horizon, no extra material is needed. However this only considers the shielding effectiveness at one point inside the dome. It gets more complicated if you want to even out the dose within the habitat. ie You don't have to worry about larger doses in different parts of the dome.

The chart shows how effective the Martian atmosphere is at reducing dosage, note the "knee" at 50gm/cc (corresponding to 35 degrees) and the gradual decrease after 200gm/cc. Regolith has much the same response.

Also, a nice idea for a hillside habitat. The thickness looks about enough to cut down dosage to acceptable levels. You could do this from cut n cover, then "simply" dome over the front.

(https://media.fromthegrapevine.com/assets/images/2015/3/villa-vals.jpg.824x0_q85.jpg)

Note to Mark_Twain: this is not a "first habitat" structure, although my data can be applied to that, this is more the kind of thing a small Martian town would have. Practicality, maximum radiation protection, attractive shape and open vistas if possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/11/2019 06:08 pm
180 g/cm2 = 180 x 100 x 100 /1000 = 1800 kg/m2, or about 1m thick?

So 1m or regolith is pretty good protection and 2m would be more than enough?  This is regolith with some water hydrated into it, I think, from the model you mentioned earlier?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/11/2019 07:56 pm
180 g/cm2 = 180 x 100 x 100 /1000 = 1800 kg/m2, or about 1m thick?

So 1m or regolith is pretty good protection and 2m would be more than enough?  This is regolith with some water hydrated into it, I think, from the model you mentioned earlier?

Yup, for compressed regolith, either compacted or in brick form. The hydrogens in it don't really amount to much.

Now, the 1m is basically "price of admission" for using regolith as shielding. Atmosphere plus the first several cm cut the dose by about half, around 0.3mSv/day, which is still something like 5 times too much. (0.66mSv/day needs to get down to ~0.06mSv for "high" background equivalent). A further 320g/cm2 (about 1.8m) only gets it down to 0.14mSv/day, so you'd probably need another metre on top of that for a total of 4m. There's a big difference between what protection astronauts will need on a mission and what colonists living out the rest of their lives / having kids need.

So for "working" facilities, probably a minimal ice or polyethylene shield will do. Big hab blocks for housing will want as thick shielding as possible, and be partially buried if possible. Of course, a nice transparent dome is what everyone wants so I'm trying to see how feasible this is in a "having a suburb under a dome" kind of way is.

What bothers me is that compared to the OLTARIS Mars regolith default, the MGS1 Mars regolith simulant has a much higher iron content and a lower density (albeit this is a powder form). Now, it makes for airtight bricks that you can basically make by filling a rubber mould and tapping it with a hammer, but it may be a problem as far as radiation shielding is concerned. OLTARIS is being taken down for maintenance for a while so I may have to wait before baking in a new material. (OLTARIS has to compile a database for each custom material which is time consuming)

https://www.sciencedirect.com/science/article/pii/S0019103518303038?via%3Dihub

However, glass has a density of 2.5g/cm3 and ALON is extraordinarily dense at 3.7g/cm3. 50cm of ALON would be "radiation neutral" but also extraordinarily difficult to make in sufficient quantities to cover a dome. However, you could use up to 30g/cm2 to shield you from the top 50% of the hemisphere, so glass etc is not useless.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/11/2019 09:43 pm
I lost my last post due to a timeout, so here's a brief summary. The Martian atmosphere and regolith can be treated as moderate-Z material, which adds dose reduction benefit until 50g/cm^2, then flattens out to 200g/cm2 before it gives any benefit again. (This is due to neutron production). The effects of regolith and atmosphere are cumulative. In other words, regolith shielding is less effective directly overhead and more effective towards the horizon.

Ack, I hate losing posts. Sorry about that.

What I'm saying is the bold summary is slightly inaccurate, because one is never "forced" to use regolith of a certain thickness. All this says to me is, "sensible regolith shield thicknesses are in the range of <50 g/cm² and >200 g/cm², cumulative of atmospheric absorption."

High-hydrogen materials like water and polyethylene do not have this "minimum regolith" penalty to provide benefit.

But no one pays the penalty, because no-one will ever make a regolith shield that thick. I mean, why would they?

The question boils down to whether a X meter thick regolith shield is cheaper than a Y meter thick water/ice shield (where X and Y both achieve the internal radiation requirements). It's probably not either/or, but some fractional regolith/H2O combination, possibly varying with vertical profile. How about icier slush on top, and dirtier regolithier slush on bottom? Is that better than uniform slushiness? If so, what's the optimal "slushiness curve?"

Obviously this is in theory, and the shield installation method itself will determine how close we can get to that.

These variables form a multi-dimensional search space, and within it there's an optimum somewhere for any given on-site H2O cost, on-site regolith cost, shielding requirement, and installation method. This tells us how to make the slab, but not what shape to make the slab.


And since we're going to be dealing with hundreds of tonnes of water ice to fuel the return Starships anyway, there is no real penalty to using it as a shielding material.

This does has economy-of-scale benefits, but the caveat is the presence of additional economic demand for water will make its price higher, not lower. And there's plenty of other demands for water: drinking, plant irrigation, production of hydrogen-rich chemicals like plastics, etc.

While applauding lamontagne's quantitative and thermodynamic approach, I don't think he means that Martian water will literally be as cheap as 45¢/gallon (12¢/liter) (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1928463#msg1928463), even impure shielding water. My understanding is lamontagne intended those numbers as general ballpark comparisons, not fully-costed price estimates, and certainly not full-fledged economic simulations.


It is also quite strong in low temperatures, and can be made bubble-free to be transparent. In addition, it is an emergency water source.

Agreed. I expect ice shielding will be a more expensive alternative to regolith where transparency is needed/desired.

My aim with exploring this design space is to make a large part of a shielded habitat able to have excellent dose reduction whilst affording a naturally-lit environment, much like the reasoning behind the Mars Ice House.

To each their aim! Ad astra.

Your use of "design space" is appropriate imo. In my mind the goal is not to make one single Best Ever Building design, but more of an RPG character creator for crafting whatever type of building is appropriate for a particular site and purpose. Select from different shield/restraint/floor designs, move the sliders to adjust height/#-of-floors/size, tweak angle for solar gain, drag and drop some airlocks, add a split level to adapt to local topography, etc.

For just natural light you don't need much surface area, nor an unobstructed view. Go into ::shudder:: Wal-Mart (a ruthlessly cost-optimized structure if there ever was one), look up, and notice how little a fraction of roof area the skylights take. Obviously shorter interiors will have closer spaced lights, probably via octopus light tubes. The slab-penetrating tubes can be curved/angled to minimize radiation leakage, essentially a smaller version of the mirrored louver shielding Gerard K. O'Neill et. al. designed for their solar agricultural space colonies.

If the goal was psychological or other benefits from windows or non-trivial plant growth then this would be inadequate, but just for natural lighting it should work fine. Of course it doesn't work at night or during dark dust storms.


Below I attach a traditional hemispherical dome with regolith allotted according to incoming radiation. Note that top half is basically the same: 180g/cm2 of extra material are needed before the regolith shielding becomes effective again. At the horizon, no extra material is needed. However this only considers the shielding effectiveness at one point inside the dome.

You stole the words right out of my mouth. :)

You're equating "direction the radiation comes from" with "place the radiation shielding needs to go on the building." This is a mistake imo.

By considering just a single test probe, your conceptual model begins to resemble a pinhole camera (with the probe the pinhole) which is "imaging" the building's radiation shield mass distribution as "backlit" by the spherical radiation anisotropy behind it. So you're literally geometrically projecting the one onto the other! It's exactly like a map projection. Problem is, reality is more complicated than this model.

To maximize shielding of a single central point only, the pictured dome would indeed be optimal (albeit oversized). But to provide uniform or uniform-enough shielding to the entire hab volume, you ideally want a uniform thickness "infinite plane" above you. Practically this is implemented as a large wide slab, which by virtue of scale pushes the wall shielding costs into the margins.


Note to Mark_Twain: this is not a "first habitat" structure, although my data can be applied to that, this is more the kind of thing a small Martian town would have. Practicality, maximum radiation protection, attractive shape and open vistas if possible.

Thanks for the nuance. Note that the point about shielding doesn't apply only to first habitats. In fact later Mars buildings should be even more economically optimized than early habs (ie lower cost per volume), due to ongoing technology improvements, design evolution, ISRU, and economies of scale. I did mention early habs in a few posts, but to avoid being pigeonholed I should clarify that that's not all I'm designing for. It's one niche of many. Again the idea is a Character Building Creator, not some One True Mars Building.

I still feel like "open vistas" are best done with lookout lounges on the top floor (not even a real tower is needed). Windows will still be expensive (heck, even on Earth that's true), so they are best put to use in corner "lounges" with windows on two sides. These would be many times larger than the ISS cupola, but still a far cry from the ostentatious all-glass Mars hab. For the low low price of ~one giant Starship window, you get four corner lounges good for socializing, conversation, eating, observing EVAs, watching Mars, or just stargazing (in any direction!). Like Starship, smaller windows would dot the walls, trapezoid-shaped assemblies filled with water or ice.


My sincere intend here is not to throw cold water on anyone's ideas, and to the extent that I have done so I apologize. My goal is to sharpen our collective view of the future. I completely expect that we won't all agree on colonization goals and subjective values and Big Questions, but we should at least get the same answer to this simple physics/math problem: "what geometric arrangement minimizes shield cost per unit of shielded volume?"

Since it seems that Lampyridae and I disagree on the answer (and Lampyridae, please correct me if not!), and naturally we can't both be right, so I'm curious where the discrepancy lies. It may turn out that we're each asking subtly different questions, or employing subtly different operating assumptions. I'm trying to be super-crystal-clear in my logic so we can find the discrepancy, hence my (further) lengthy pedantic ramblings...  :'( ;D

Any suggestions? Why do Lampyridae and I get different answers to the "shielding question?"

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/11/2019 10:15 pm
180 g/cm2 = 180 x 100 x 100 /1000 = 1800 kg/m2, or about 1m thick?

So 1m or regolith is pretty good protection and 2m would be more than enough?  This is regolith with some water hydrated into it, I think, from the model you mentioned earlier?

Yup, for compressed regolith, either compacted or in brick form. The hydrogens in it don't really amount to much.

Now, the 1m is basically "price of admission" for using regolith as shielding. Atmosphere plus the first several cm cut the dose by about half, around 0.3mSv/day, which is still something like 5 times too much. (0.66mSv/day needs to get down to ~0.06mSv for "high" background equivalent). A further 320g/cm2 (about 1.8m) only gets it down to 0.14mSv/day, so you'd probably need another metre on top of that for a total of 4m. There's a big difference between what protection astronauts will need on a mission and what colonists living out the rest of their lives / having kids need.

So for "working" facilities, probably a minimal ice or polyethylene shield will do. Big hab blocks for housing will want as thick shielding as possible, and be partially buried if possible. Of course, a nice transparent dome is what everyone wants so I'm trying to see how feasible this is in a "having a suburb under a dome" kind of way is.

What bothers me is that compared to the OLTARIS Mars regolith default, the MGS1 Mars regolith simulant has a much higher iron content and a lower density (albeit this is a powder form). Now, it makes for airtight bricks that you can basically make by filling a rubber mould and tapping it with a hammer, but it may be a problem as far as radiation shielding is concerned. OLTARIS is being taken down for maintenance for a while so I may have to wait before baking in a new material. (OLTARIS has to compile a database for each custom material which is time consuming)

https://www.sciencedirect.com/science/article/pii/S0019103518303038?via%3Dihub

However, glass has a density of 2.5g/cm3 and ALON is extraordinarily dense at 3.7g/cm3. 50cm of ALON would be "radiation neutral" but also extraordinarily difficult to make in sufficient quantities to cover a dome. However, you could use up to 30g/cm2 to shield you from the top 50% of the hemisphere, so glass etc is not useless.
I wonder how much time would be spent 'under the dome' compared to the time is more sheltered portions of the habitat.  If you have sheltered offices, schools and living quarters, perhaps you total yearly radiation dose is not that high from walking in the 'open'?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/11/2019 10:25 pm
Treated water on Earth in a typical northern city is about 0,4$ per m3 to produce and distribute, with a loss ratio of about 20-30% (lots of leaks).  This is from my civil engineering friends.

So water on Earth is about 0,4 cents per liter, or 30 times less than my estimate.  But I agree water on Mars is more expensive than what I calculated, since I did not filter, pump or finance it.  I just melted it.  That being said it is very likely water can be melted by colony waste heat, so who knows exactly what the cost will be?  Still, a lot cheaper than pretty much everything else, except sand :-)

What I worry about regarding water shielding is sublimation of the water, but I guess that would be managed by using some kind of plastic film?  With the water condensing out every night?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 04/12/2019 01:30 am
I lost my last post due to a timeout, so here's a brief summary. The Martian atmosphere and regolith can be treated as moderate-Z material, which adds dose reduction benefit until 50g/cm^2, then flattens out to 200g/cm2 before it gives any benefit again. (This is due to neutron production). The effects of regolith and atmosphere are cumulative. In other words, regolith shielding is less effective directly overhead and more effective towards the horizon.

So just to clarify. This means that you need more regolith to shield radiation from above than from the sides of your habitat?
Title: Re: Envisioning Amazing Martian Habitats
Post by: scienceguy on 04/12/2019 01:36 am
I haven't read the whole thread, but has anyone proposed half regolith and half water for radiation protection? Like this:
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/12/2019 06:29 am
So just to clarify. This means that you need more regolith to shield radiation from above than from the sides of your habitat?

Yup. Although when you work out how much regolith you're going to need for effective dose reduction, it's not that big of a difference in thickness between walls and sides.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 04/12/2019 10:42 pm
The surface radiation shielding requirements really preclude most of the elegant and beautiful habitat ideas that are out there. Also, they necessitate huge piles of heavy shielding that are resource-intensive to build and are also demanding on the main structure of the habitat, which may only sustain its shape actively (i.e. via pressurization).

These are all important factors that lead me to think that tunnels and caverns in bedrock are the best solution for the primary interior space of the habitat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: GregTheGrumpy on 04/12/2019 10:50 pm
While underground areas (tunnels, et. al.) are probably not what most folks think of as amazing, I'm sure that there will be some amazing spaces built underground.  For the early stages, I do believe underground is the way to go with access points (and probably visitation "lounges") will dot the surface.  They will will be connected via tunnel and connect to the main main living and work spaces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 04/13/2019 06:52 am
While underground areas (tunnels, et. al.) are probably not what most folks think of as amazing, I'm sure that there will be some amazing spaces built underground.  For the early stages, I do believe underground is the way to go with access points (and probably visitation "lounges") will dot the surface.  They will will be connected via tunnel and connect to the main main living and work spaces.

I think the same. Elon Musk mentioned working in cheap underground volume and living in geodesic domes on the surface. But I don't think that's feasible. Living and working underground with a dome or few domes as parks at the surface, filled with a variety of plants for recreation. Just the knowledge they are there and accessible will do much to improve quality of life, even if people visit there infrequently.

A new thought just entered my mind. I don't think this has been suggested yet. Have a small dome which is fully transparent as an observation point to see the night sky unobstructed may be attractive so some like me.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/13/2019 06:41 pm
While underground areas (tunnels, et. al.) are probably not what most folks think of as amazing, I'm sure that there will be some amazing spaces built underground.  For the early stages, I do believe underground is the way to go with access points (and probably visitation "lounges") will dot the surface.  They will will be connected via tunnel and connect to the main main living and work spaces.

I think the same. Elon Musk mentioned working in cheap underground volume and living in geodesic domes on the surface. But I don't think that's feasible. Living and working underground with a dome or few domes as parks at the surface, filled with a variety of plants for recreation. Just the knowledge they are there and accessible will do much to improve quality of life, even if people visit there infrequently.

A new thought just entered my mind. I don't think this has been suggested yet. Have a small dome which is fully transparent as an observation point to see the night sky unobstructed may be attractive so some like me.
In about half an hour....
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 04/13/2019 08:26 pm
While underground areas (tunnels, et. al.) are probably not what most folks think of as amazing

Well, you can do something like this: https://youtu.be/-xLofcccu1w
Title: Re: Envisioning Amazing Martian Habitats
Post by: GregTheGrumpy on 04/13/2019 11:23 pm
While underground areas (tunnels, et. al.) are probably not what most folks think of as amazing

Well, you can do something like this: https://www.youtube.com/watch?v=-xLofcccu1w

Well, That would indeed be amazing.  I expect fully fun and enjoyable places can and will be built completely underground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/14/2019 08:49 pm
Like we keep saying, digging a tunnel is not a simple or cheap affair.

Six metres of Martian regolith is sufficient to provide comparable-to-Earth levels of radiation protection. After that, it's pointless and adds cost. This six metres is mostly dust, concretions and loose rock anyway, unless you choose to build on exposed rock... and then have to go find permafrost-containing frozen mud elsewhere. Permafrost will probably be excavated in something like an open pit manner, so you can put your structure in there and immediately benefit from being partially below ground. Line with marscrete (it's already been scooped out or you) and put your choice of structure overhead: barrel vault, dome, slab etc. Use clear ice in acrylic for transparent skylights. Or use a thin-ish concrete roof and heap the dirt over that. But marscrete is very, very easy to make from Martian soil (easier than concrete on Earth). Just compact the dirt and it forms an extremely strong brick.

Concrete is pretty good radiation shielding material, simply because it's moderate-Z and dense: 2.4g/cc. You only need 4 metres of it to get the equivalent of Earth's atmosphere in shielding: 1 000g/cm2. In practice, it needn't be so thick; most radiation through a wall comes in at an angle so the effective depth is greater. A vertical wall only need to be 2-3m thick or so to provide a very high level of shielding. Internal concrete walls just add to the shielding effect. We already have examples of such thick-walled concrete buildings.

The Germans in WWII made their bunkers aboveground, called hochbunkers ("high bunkers"). This was because building them underground was too expensive and too time consuming. They are so tough that Germany mostly gave up on getting rid of them. This one in Hamburg has walls up to 3.5m thick, was 75mx75mx35m in dimensions. This would be more than enough space for a couple of hundred people, plus a generously sized garden. Enough for about half a hectare or one and a bit acres.

(https://i.pinimg.com/originals/47/c3/07/47c307ac9c6eda83535cd8c7aeca8fe7.jpg)

This other one has walls 2.5m thick.

(https://i2.wp.com/www.leopoldlambert.net/wp-content/uploads/2014/12/Flakturm-Archives-Leopold-Lambert-3.jpg)

Naturally though, we don't want to create such weird brutalist monstrosities. My point is that integrating the shielding is not that hard. It is much easier to go 10 storeys straight up than to dig 10 storeys down.
Title: Re: Envisioning Amazing Martian Habitats
Post by: BZHSpace on 04/15/2019 07:44 am
I agree with what Lampyridae said, digging tunnels isn't an easy task. You've to sent some heavy materials. I think the 3D printed option with a bit of digging through the surface to place life/water systems are the best option for the Mars habitat, if you take the 3D printed technology there are multiple options for making intelligent wall and structure for a low cost of material, time and an high efficiency. I see a project made by Foster + partner that use 3D printer to build on the Moon a outpost which could resist to an high radiation environment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: colbourne on 04/15/2019 12:23 pm
With a little exploration before hand , initially from orbit, we should be able to find suitable tunnels or holes that we can build the base in without extensive tunneling being required. Maybe build the structure in the hole and back fill if necessary, for extra shielding.
I still think that a base near the ice caps makes sense , mainly for easy access to water.  A base here could be cut into the ice or in a naturally occurring hole in the ice.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 04/15/2019 02:30 pm
My point is that integrating the shielding is not that hard. It is much easier to go 10 storeys straight up than to dig 10 storeys down.
I'm not sure that's true, if one includes the massive infrastructure for producing concrete and then all the other skyscraper construction infrastructure that is needed (cranes, rebar, etc.).  There is a lot less work needed to make a tunnel habitable (dig, line, pressurize and heat), and a lot less heavy support equipment and industrial infrastructure needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/15/2019 04:11 pm
My point is that integrating the shielding is not that hard. It is much easier to go 10 storeys straight up than to dig 10 storeys down.
I'm not sure that's true, if one includes the massive infrastructure for producing concrete and then all the other skyscraper construction infrastructure that is needed (cranes, rebar, etc.).  There is a lot less work needed to make a tunnel habitable (dig, line, pressurize and heat), and a lot less heavy support equipment and industrial infrastructure needed.

Or you can skip the digging and its associated costs and risks, leave your tunnel liner on the surface and cover it with some regolith.

Tunnels are not dug for free. Even on Earth they cost millions: in the UK, a transport tunnel costs about 20 million pounds per kilometre.

Our current experience with Martian tunnelling is a a probe unable to even get below the surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 04/15/2019 07:50 pm
Or you can skip the digging and its associated costs and risks, leave your tunnel liner on the surface and cover it with some regolith.
If you're using loose regolith, you're essentially creating a large sloping hill, and piling it up high enough to accommodate several metres of thickness on top requires a lot of regolith that will itself have to be dug/scraped.

Quote
Tunnels are not dug for free. Even on Earth they cost millions: in the UK, a transport tunnel costs about 20 million pounds per kilometre.
And how much does it cost to construct a skyscraper with similar volume?  Now add several additional metres of concrete on the walls and roof, and the appropriate structures to retain them.

Quote
Our current experience with Martian tunnelling is a a probe unable to even get below the surface.
I don't think the approach being used is very reflective of using a modern tunnel boring machine.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/15/2019 10:09 pm
You want an apples to apples quote? I'll give you one.

In most places around the world, the material cost of 30Mpa concrete is $100/m3 (near $150/m3 in Aus, as low as $60 in China, about $100 in most of Europe). Laying it out brings it up to around $120/m3 - $135/m3. The bare minimum cost of tunnelling in very competent ground is $50/m3, in "typical" geological settings is it is $100m3 and reaches $300/m3.

You will not find competent bedrock on a planet with zero tectonic activity that's been pummeled with meteorites for billions of years. But let's say a miracle happens. It's reasonably competent ground.

So creating a cubic metre of concrete is comparable to creating a cubic metre of "free" underground volume. And you still need to tunnel in a vacuum and without water or find the water to do the tunnelling, reject the waste heat, make concrete and come up with some kind of shotcrete that works on Mars and also manufacture or import rockbolts. We'll say that's equivalent in difficulty to erecting concrete walls on Mars on a volume basis.

Digging a 1km tunnel 8m internal diameter (highway tunnel size) gives you 50 000m3. That's equivalent to a modestly sized 5 storey office block, 57m on a side. The office block makes much greater use of the volume because tunnels are circular to make tunnelling easier and I am trying to minimise the lining material volume requirements. Cut n cover tunnels are typically rectangular in cross section. Internal walls and all the fitments like lighting, tiling, ventilation, emergency airlocks etc are assumed to be equal in cost between underground and aboveground.

This equivalent modest office block with 3m of concrete radiation shielding (instead of filling the walls with regolith) will use some 20 000m3 of concrete. If it were a dome shape, it would shield a dome 64m in diameter with a somewhat more optimal 65 000m3 of volume.

Bottom line: to excavate a single cubic metre is the same cost as to build a cubic metre of concrete. If you're lucky with the geology and know how to deal with it.

https://www.turnerandtownsend.com/media/2412/international-construction-market-survey-2017-final.pdf

https://www.researchgate.net/publication/314096492_Assessing_and_benchmarking_the_construction_cost_of_tunnels

If you want marscrete, it looks like you can make it with a rubber mould and a hammer. The FeOx acts as a binder.

https://www.nature.com/articles/s41598-017-01157-w
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/16/2019 02:26 am
Re: Tunnels.

This doesn't challenge Lampyridae's point, but we should get out of the habit of saying "tunnels" for the underground habitats. While I also use "tunnel" and "TBM" as a shorthand, actual tunnels aren't a smart way to build volume underground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 04/16/2019 04:49 am
My view is that a tunnel is a good starting point.  Bore a tunnel into / through a suitable body with a TBM and then use a roadheader, or similar,  to expand the interior space into a more habitable area.  The circular tunnel cross section may be more useful for fitting airlocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/16/2019 10:52 am
My view is that a tunnel is a good starting point.  Bore a tunnel into / through a suitable body with a TBM and then use a roadheader, or similar,  to expand the interior space into a more habitable area.  The circular tunnel cross section may be more useful for fitting airlocks.

TBMs are not the right technology for short entrance tunnels like that. Typically you'd use other machines to cut an entrance suitable for the TBM. You might also flow concrete into the surface layer to increase integrity, because TBMs apparently don't like unconsolidated rock.

(Also roadheaders and similar machines can cut any shape hole.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/16/2019 11:06 am
Re: Tunnels.

This doesn't challenge Lampyridae's point, but we should get out of the habit of saying "tunnels" for the underground habitats. While I also use "tunnel" and "TBM" as a shorthand, actual tunnels aren't a smart way to build volume underground.

Well, let's have some terms down, then.

Tunnel - long, straight excavation
Shaft - long, vertical excavation
Rock cavern - just an excavated cavern for putting things in, usually in very competent rock (but still requires shotcrete stabilisation)
Lined rock cavern - the same but with a lining, usually for underground pressurised natural gas storage (as far as I know no-one has actually done this on a commercial scale)
Shotcrete - quick-drying cement mixed with steel fibres sprayed onto rock walls to prevent collapse and rockfall
Rock bolts - steel rods a metre or more long driven into rock walls to stabilise them
Lining - various
Rock Quality Index - various names for this, low ratings imply that bedrock is highly fractured and rock walls are prone to collapse. Rock cohesion is also subject to change over time: wet fractures have a lower angle of repose than wet ones, for example.
Shear zone / fracture zone - zone of fractures created by excavation. Removing rock mass changes the pressure distriution and fracturing is inevitable unless it is very strong, competent rock
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/16/2019 11:45 am
Huh, I can't believe I forgot about this.

Oasis 21 is an underground shopping mall and bus station next to a subway station in Nagoya, Japan. The "spaceship" thingy is a transparent roof partially covered with water. Thick frosted glass panels serve as skylights for the shopping area below. At night they light up the "spaceship" with coloured lighting. They'll probably do that a lot on Mars - a nice, easy way to prettify things.

http://www.sakaepark.co.jp/en/

(https://cdn.zekkei-japan.jp/images/spots/b2f57c313ef91e566c54b07d8a0456b9.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 04/16/2019 02:29 pm
If we're comparing methods, it's important to factor in the infrastructure necessary for producing concrete (and rebar or some similar reinforcement) via ISRU, as well as whatever construction equipment (such as cranes, scaffolding, etc.) that would be needed.  I don't know how the actual economics of it would work out.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/17/2019 03:03 am
The surface radiation shielding requirements really preclude most of the elegant and beautiful habitat ideas that are out there.

A little imagination can fix this. The shielding will probably be covered by a thermal insulating "tent" so it doubles as a large thermal mass, and the cover can be tastefully decorated. Upthread I suggested taking inspiration from Parisian block houses:

(https://i.imgur.com/vbXF0XN.jpg)

Or use a thin-ish concrete roof and heap the dirt over that. But marscrete is very, very easy to make from Martian soil (easier than concrete on Earth). Just compact the dirt and it forms an extremely strong brick.

Great post and great points.

Truly marscrete is a powerful tool. But sifting large stones, filling compressed-mars-block presses, and then laboriously (robot or human) stacking the blocks on the roof is a lot more work than dumping some loose regolith on the roof and optionally driving over it for compaction. Remember, Keep It Simple and Stupid. Or to misquote Einstein: "As simple as possible, and no simpler." :)

Blocks for making the walls, cheaper piled regolith on the roof? This cost structure would favor large area-to-perimeter ratios. One option would be to put buildings close together and make the regolith roofs continuous between them, expanding and relocating block walls as needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 04/17/2019 05:19 am
The surface radiation shielding requirements really preclude most of the elegant and beautiful habitat ideas that are out there.

A little imagination can fix this. The shielding will probably be covered by a thermal insulating "tent" so it doubles as a large thermal mass, and the cover can be tastefully decorated. Upthread I suggested taking inspiration from Parisian block houses:
My favourite shape for above ground is cylindrical skyscrapers.
* Good shielding for all but top levels because radiation from the side has to pass through a lot more layers.
* A pool or water cistern on top would also help with shielding
* Best panoramic viewing area design. IMO Domes are really bad by comparison, unless you mainly like looking up.
* Unlike a dome you can keep extending it, probably to impressive heights on Mars.
* Note: you could supplement the light with surrounding arrays of mirrors, eg you could get earth-levels of light if that were desired. This is a bit like the layout of solar tower, and an actual solar tower function could be an option.

I imagine this supplementing a mainly below ground colony to provide above-ground viewing and gardens, but it is also a pretty common and reasonable initial habitat shape.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/17/2019 05:22 am
Ok here's a really off-the-wall crazy idea. Might just work though... 

If we're using H2O shielding for the walls and/or roof, what if it does double-duty as a photobioreactor? Algae has lots of problems (cue endless debate redux), but I'm thinking closer to Bren Smith's 3D ocean farming:

https://www.youtube.com/watch?v=j8ViaskDSeI

TL;DW it's shellfish-kelp polyculture that's highly productive, filters pollution, and efficiently cycles carbon. Kelp solves many of algae's problems: no cyanotoxins, far more edible (kelp noodles, sashimi rolls, etc), and it doesn't have nearly the same problems of bacterial competition and undesirable population mutations as algae colonies do. Kelp produces much of the omega-3 oils found in fish (fish don't synthesize omega-3), and kelp is the fastest-growing and most efficient multicellular plant (much better than any land plant). You might say kelp is methalox to algae's hydrolox. :D

Plus you get oysters, clams, mussels, scallops, etc. These are filter feeder organisms that remove nitrogen wastes, so of course for food production tanks you want to be careful about inputs and test before eating. Radiation isn't a concern for short-lived organisms like food crops. No humans need enter the tanks, just reel in the mussel socks etc, cycle the water-lock, and harvest (or do maintenance, reseed etc).

Obviously you don't want to bring shellfish feed from Earth, or even purpose-manufacture it on Mars, but rather incorporate it into the closed-loop life support. Waste from the hydroponics or aquaculture, grey water, processed black water, etc can be used. Here on Earth 3D ocean farms are used to soak up fertilizer and stormwater runoff in rivers that otherwise causes ocean dead zones, and the shellfish are perfectly safe to eat. /TL;DW


Stacking a few functions here:

• Radiation shielding
• Contingency thermal mass, also smooths day-night temperature
• Gravity-fed water storage for sprinklers, etc
• O2 production/CO2 removal
• Food/feed production
• Oil production
• Water filtration
• Natural lighting maybe
• probably more

Plus that nice soothing view of Mars through the south window: a lush, green, dappled kelp forest.  8)

Ultimately this can be as small as a single window mini-garden, as elaborate as "living in an aquarium," or as scaled and austere as transparent bags over a waterproof membrane roof. All depends on your goals.

Technical challenges? Plenty: seawater, leaks, sloshing, mutant kelpmonsters, etc. But these have solutions, and the potential payoff is so good it's worth investigating imo. And it would certainly be amazing!

Shielding fishtanks anyone?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/17/2019 12:22 pm
Ok here's a really off-the-wall crazy idea. Might just work though... 

If we're using H2O shielding for the walls and/or roof, what if it does double-duty as a photobioreactor? Algae has lots of problems (cue endless debate redux), but I'm thinking closer to Bren Smith's 3D ocean farming:

https://www.youtube.com/watch?v=j8ViaskDSeI

TL;DW it's shellfish-kelp polyculture that's highly productive, filters pollution, and efficiently cycles carbon. Kelp solves many of algae's problems: no cyanotoxins, far more edible (kelp noodles, sashimi rolls, etc), and it doesn't have nearly the same problems of bacterial competition and undesirable population mutations as algae colonies do. Kelp produces much of the omega-3 oils found in fish (fish don't synthesize omega-3), and kelp is the fastest-growing and most efficient multicellular plant (much better than any land plant). You might say kelp is methalox to algae's hydrolox. :D

Plus you get oysters, clams, mussels, scallops, etc. These are filter feeder organisms that remove nitrogen wastes, so of course for food production tanks you want to be careful about inputs and test before eating. Radiation isn't a concern for short-lived organisms like food crops. No humans need enter the tanks, just reel in the mussel socks etc, cycle the water-lock, and harvest (or do maintenance, reseed etc).

Obviously you don't want to bring shellfish feed from Earth, or even purpose-manufacture it on Mars, but rather incorporate it into the closed-loop life support. Waste from the hydroponics or aquaculture, grey water, processed black water, etc can be used. Here on Earth 3D ocean farms are used to soak up fertilizer and stormwater runoff in rivers that otherwise causes ocean dead zones, and the shellfish are perfectly safe to eat. /TL;DW


Stacking a few functions here:

• Radiation shielding
• Contingency thermal mass, also smooths day-night temperature
• Gravity-fed water storage for sprinklers, etc
• O2 production/CO2 removal
• Food/feed production
• Oil production
• Water filtration
• Natural lighting maybe
• probably more

Plus that nice soothing view of Mars through the south window: a lush, green, dappled kelp forest.  8)

Ultimately this can be as small as a single window mini-garden, as elaborate as "living in an aquarium," or as scaled and austere as transparent bags over a waterproof membrane roof. All depends on your goals.

Technical challenges? Plenty: seawater, leaks, sloshing, mutant kelpmonsters, etc. But these have solutions, and the potential payoff is so good it's worth investigating imo. And it would certainly be amazing!

Shielding fishtanks anyone?
Sounds good, why not go the whole hog and have fish as well?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/17/2019 12:54 pm
Eventually you would need some kind of neutral buoyancy tank to keep your astronaut corps' spacewalking skills sharp, or to train new ones from the colonists.

Also useful for just plain swimming in. I like the idea of a long, toroidal habitat with a water roof. You could take a rowboat out for an afternoon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/17/2019 07:44 pm
Ok here's a really off-the-wall crazy idea. Might just work though... 

If we're using H2O shielding for the walls and/or roof, what if it does double-duty as a photobioreactor? Algae has lots of problems (cue endless debate redux), but I'm thinking closer to Bren Smith's 3D ocean farming:

https://www.youtube.com/watch?v=j8ViaskDSeI

TL;DW it's shellfish-kelp polyculture that's highly productive, filters pollution, and efficiently cycles carbon. Kelp solves many of algae's problems: no cyanotoxins, far more edible (kelp noodles, sashimi rolls, etc), and it doesn't have nearly the same problems of bacterial competition and undesirable population mutations as algae colonies do. Kelp produces much of the omega-3 oils found in fish (fish don't synthesize omega-3), and kelp is the fastest-growing and most efficient multicellular plant (much better than any land plant). You might say kelp is methalox to algae's hydrolox. :D

Plus you get oysters, clams, mussels, scallops, etc. These are filter feeder organisms that remove nitrogen wastes, so of course for food production tanks you want to be careful about inputs and test before eating. Radiation isn't a concern for short-lived organisms like food crops. No humans need enter the tanks, just reel in the mussel socks etc, cycle the water-lock, and harvest (or do maintenance, reseed etc).

Obviously you don't want to bring shellfish feed from Earth, or even purpose-manufacture it on Mars, but rather incorporate it into the closed-loop life support. Waste from the hydroponics or aquaculture, grey water, processed black water, etc can be used. Here on Earth 3D ocean farms are used to soak up fertilizer and stormwater runoff in rivers that otherwise causes ocean dead zones, and the shellfish are perfectly safe to eat. /TL;DW


Stacking a few functions here:

• Radiation shielding
• Contingency thermal mass, also smooths day-night temperature
• Gravity-fed water storage for sprinklers, etc
• O2 production/CO2 removal
• Food/feed production
• Oil production
• Water filtration
• Natural lighting maybe
• probably more

Plus that nice soothing view of Mars through the south window: a lush, green, dappled kelp forest.  8)

Ultimately this can be as small as a single window mini-garden, as elaborate as "living in an aquarium," or as scaled and austere as transparent bags over a waterproof membrane roof. All depends on your goals.

Technical challenges? Plenty: seawater, leaks, sloshing, mutant kelpmonsters, etc. But these have solutions, and the potential payoff is so good it's worth investigating imo. And it would certainly be amazing!

Shielding fishtanks anyone?
Sounds good, why not go the whole hog and have fish as well?

For sure that's an option, but the added trophic layer reduces food and O2 productivity. You're effectively competing with the fish for the primary photosynthetic productivity of food and oxygen. Fish may be tasty, but they're less efficient (and therefore more expensive per unit of nutrition).

I think some tanks will definitely have fish, no doubt about it! But since you asked "why not," I told you. ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/17/2019 07:47 pm
Ok here's a really off-the-wall crazy idea. Might just work though... 

If we're using H2O shielding for the walls and/or roof, what if it does double-duty as a photobioreactor? Algae has lots of problems (cue endless debate redux), but I'm thinking closer to Bren Smith's 3D ocean farming:

https://www.youtube.com/watch?v=j8ViaskDSeI

TL;DW it's shellfish-kelp polyculture that's highly productive, filters pollution, and efficiently cycles carbon. Kelp solves many of algae's problems: no cyanotoxins, far more edible (kelp noodles, sashimi rolls, etc), and it doesn't have nearly the same problems of bacterial competition and undesirable population mutations as algae colonies do. Kelp produces much of the omega-3 oils found in fish (fish don't synthesize omega-3), and kelp is the fastest-growing and most efficient multicellular plant (much better than any land plant). You might say kelp is methalox to algae's hydrolox. :D

Plus you get oysters, clams, mussels, scallops, etc. These are filter feeder organisms that remove nitrogen wastes, so of course for food production tanks you want to be careful about inputs and test before eating. Radiation isn't a concern for short-lived organisms like food crops. No humans need enter the tanks, just reel in the mussel socks etc, cycle the water-lock, and harvest (or do maintenance, reseed etc).

Obviously you don't want to bring shellfish feed from Earth, or even purpose-manufacture it on Mars, but rather incorporate it into the closed-loop life support. Waste from the hydroponics or aquaculture, grey water, processed black water, etc can be used. Here on Earth 3D ocean farms are used to soak up fertilizer and stormwater runoff in rivers that otherwise causes ocean dead zones, and the shellfish are perfectly safe to eat. /TL;DW


Stacking a few functions here:

• Radiation shielding
• Contingency thermal mass, also smooths day-night temperature
• Gravity-fed water storage for sprinklers, etc
• O2 production/CO2 removal
• Food/feed production
• Oil production
• Water filtration
• Natural lighting maybe
• probably more

Plus that nice soothing view of Mars through the south window: a lush, green, dappled kelp forest.  8)

Ultimately this can be as small as a single window mini-garden, as elaborate as "living in an aquarium," or as scaled and austere as transparent bags over a waterproof membrane roof. All depends on your goals.

Technical challenges? Plenty: seawater, leaks, sloshing, mutant kelpmonsters, etc. But these have solutions, and the potential payoff is so good it's worth investigating imo. And it would certainly be amazing!

Shielding fishtanks anyone?
Sounds good, why not go the whole hog and have fish as well?

For sure that's an option, but the added trophic layer reduces food and O2 productivity. You're effectively competing with the fish for the primary photosynthetic productivity of food and oxygen. Fish may be tasty, but they're less efficient (and therefore more expensive per unit of nutrition).

I think some tanks will definitely have fish, no doubt about it! But since you asked "why not," I told you. ;)
At the same time, does a farm like that work without fishpoop to close the cycle? The farm assumes certain nutrients to drift in from the whole rest of the ocean, an assumption that a martian kelptank cannot make.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/17/2019 10:34 pm
Ok here's a really off-the-wall crazy idea. Might just work though... 

If we're using H2O shielding for the walls and/or roof, what if it does double-duty as a photobioreactor? Algae has lots of problems (cue endless debate redux), but I'm thinking closer to Bren Smith's 3D ocean farming:

https://www.youtube.com/watch?v=j8ViaskDSeI

TL;DW it's shellfish-kelp polyculture that's highly productive, filters pollution, and efficiently cycles carbon. Kelp solves many of algae's problems: no cyanotoxins, far more edible (kelp noodles, sashimi rolls, etc), and it doesn't have nearly the same problems of bacterial competition and undesirable population mutations as algae colonies do. Kelp produces much of the omega-3 oils found in fish (fish don't synthesize omega-3), and kelp is the fastest-growing and most efficient multicellular plant (much better than any land plant). You might say kelp is methalox to algae's hydrolox. :D

Plus you get oysters, clams, mussels, scallops, etc. These are filter feeder organisms that remove nitrogen wastes, so of course for food production tanks you want to be careful about inputs and test before eating. Radiation isn't a concern for short-lived organisms like food crops. No humans need enter the tanks, just reel in the mussel socks etc, cycle the water-lock, and harvest (or do maintenance, reseed etc).

Obviously you don't want to bring shellfish feed from Earth, or even purpose-manufacture it on Mars, but rather incorporate it into the closed-loop life support. Waste from the hydroponics or aquaculture, grey water, processed black water, etc can be used. Here on Earth 3D ocean farms are used to soak up fertilizer and stormwater runoff in rivers that otherwise causes ocean dead zones, and the shellfish are perfectly safe to eat. /TL;DW


Stacking a few functions here:

• Radiation shielding
• Contingency thermal mass, also smooths day-night temperature
• Gravity-fed water storage for sprinklers, etc
• O2 production/CO2 removal
• Food/feed production
• Oil production
• Water filtration
• Natural lighting maybe
• probably more

Plus that nice soothing view of Mars through the south window: a lush, green, dappled kelp forest.  8)

Ultimately this can be as small as a single window mini-garden, as elaborate as "living in an aquarium," or as scaled and austere as transparent bags over a waterproof membrane roof. All depends on your goals.

Technical challenges? Plenty: seawater, leaks, sloshing, mutant kelpmonsters, etc. But these have solutions, and the potential payoff is so good it's worth investigating imo. And it would certainly be amazing!

Shielding fishtanks anyone?
Sounds good, why not go the whole hog and have fish as well?

For sure that's an option, but the added trophic layer reduces food and O2 productivity. You're effectively competing with the fish for the primary photosynthetic productivity of food and oxygen. Fish may be tasty, but they're less efficient (and therefore more expensive per unit of nutrition).

I think some tanks will definitely have fish, no doubt about it! But since you asked "why not," I told you. ;)
At the same time, does a farm like that work without fishpoop to close the cycle? The farm assumes certain nutrients to drift in from the whole rest of the ocean, an assumption that a martian kelptank cannot make.
I think it would work just fine with human poop to if suitably processed. I'm sure that an analysis could be made of the nutritional requirements of kelp and the right balance and quantity of nutrients could be achieved artificialy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/18/2019 09:59 am
Yeah, before we reinvent the wheel and stuff, there's a thread for agriculture which includes things like aquaculture.

TLDR, fish and chips are perfectly viable.

https://forum.nasaspaceflight.com/index.php?topic=35877.0
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/18/2019 10:43 pm
Yeah, before we reinvent the wheel and stuff, there's a thread for agriculture which includes things like aquaculture.

TLDR, fish and chips are perfectly viable.

https://forum.nasaspaceflight.com/index.php?topic=35877.0

Yes thank you. I was bringing up the architectural implications, ie performing multiple hab functions (including aesthetic) with a single architectural element that ordinarily provides only radiation shielding. Detailed discussion of the food production implementation itself should go to the agriculture thread, but in this thread merely state your assumptions.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/22/2019 01:02 pm
This got mistakenly posted in the SpaceShip Crane thread, so to keep on-topic I'll reply here.

Instead of starting from what the most practical and easy  to build structure is. How about deciding what would be preferred by the inhabitants , and then working out how it can be built whilst providing the required radiation shielding and strength.

Because as it turns out, one of the biggest things inhabitants prefer is "cheaper rent." :)

Nothing wrong with reenacting MTV's Cribs on Mars, but it's hardly a challenge. Engineering gets a lot easier when the customer says "money is no object." It's like playing KSP in Sandbox vs Career mode.

I presume after having travelled so far the inhabitants would like to have a good view of the surrounding area, and would not want to live all the time underground or without a view.

Exactly why it's possible that the only above-ground structures might be (insanely expensive, communally- or patron-funded) scenic viewing domes. Maximize inhabitant enjoyment from scenic vistas while still maintaining low total cost of living for colonists.

Personally I hope that this scenario doesn't come true, and that Mars has tunnels and real above-ground buildings too. That's why my focus is on designing cost-effective above-ground structures.


Waht is the best way of making a transparent large window which also provides enough protection ?


Depends on your definition of "best." ;) Cheapest? Most reliable? Most subjectively 'amazing' at any cost?

Note that if the windows get too large, they become out-of-reach for colonists of modest means. I would argue what many smaller windows that can be installed in an individual apartment / residential habs will provide a lot of aggregate colonist happiness too (and at substantially lower cost). See the "my picket fence" psychology. So I think they'll have both large and small windows, just like Starship has a large communal window and many smaller windows located in individual cabins.

For my own definition of "best," the aforementioned aquarium walls are the way to go. They produce oxygen, look great, modulate the day/night thermal cycle, and introduce some much-needed green nature into a barren landscape. Internal volume will be expensive, so trees and forests will be vanishingly rare (probably limited to the Musk City Conservation Zoo and Aquarium). This will give an opportunity for ordinary homes to enjoy beautiful dappled sunlight filtered through living, breathing, swaying, natural leaves. Talk about amazing!

Besides, a water tank is the cheapest design for an adequately shielded window. If you're doing all that work to build transparent water tanks anyway, why not add some small incremental gear and get supplemental oxygen/food production and decorative plants along with it? Also aquatic plants are vastly more productive than terrestrial plants, and this prevents building an "aquarium within an aquarium."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/23/2019 03:05 pm
Note however that in a fish or prawn farm (as opposed to an aquarium), the water turbidity mostly due to phytoplankton is extremely high, visibility optimally being about 30cm.

http://www.vietlinhjsc.com/en/aquaculture/water-turbidity.asp
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/24/2019 03:17 pm
I generally make an assumption when talking about metal framing in this context, but since people are occasionally doing the actual calculations, I thought I'd ask...

Obviously you can create a purely flexible tensile structure. But if you are using metal (steel/aluminium) and assume a gauge-thickness sufficient for a rigid shell or frame to support 10t/m² tensile pressure, is it self-supporting when unpressurised? And is there a good/consistent rule of thumb for what kind of tonnes-per-square-metre compressive load (of additional shielding-mass) it could support for ten tonnes-per-square-metre tensile load.

The top dome of the S-IVB was 0.8mm thick and operated at 2.7-2.9 bars. The aft tank dome was ("sheets" - the source is not quite clear on what this means). The walls were milled from 1.9cm thick aluminium into a waffle grid pattern. Generally tanks have stringers or waffling to keep with loads on the top.

https://history.nasa.gov/SP-4206/ch6.htm

A pressure vessel on Mars would need the following:

1. Top dome reinforcement to deal with regolith shield load
2. Sidewall reinforcement to carry load and deal with potential buckling
3. Bottom dome reinforcement is not necessary as the sidewalls can transmit the forces straight down via struts onto baseplates

Of course, you can just sandbag an arch all the way over the top of the pressure vessel, but that gets difficult when it's 6m and you need a minimum of 1.5m for any benefit.

Of course, if you just pile regolith around a habitat, you actually screen more radiation than if you piled it on top, because only 30% of the sky hemisphere is above 45 degrees.

Here's some examples of how habitats could be buried: semi-exposed, semi-exposed with embankments and of course fully buried. But semi-exposed with embankments gives pretty good radiation shielding in conjunction with a reasonable water ice shield on top. (2m cuts by 50%, 3m cuts by 70%...) Just arrange the internals so that loitering in radiation hot spots is discouraged or prevented, eg with a nice vertical hydroponic garden in the centre.

0.33mSv/day is a 50% dose reduction, 0.1mSv/day is a lower dose rate than certain high altitude, high latitude airline flights and 0.025mS/day is only twice the average background radiation on Earth.

The thing that bugs me about this is that humans prefer a room with a view, and this doesn't provide one. Studies have shown that a hospital room looking out onto a nature scene speed recovery compared to one looking at a brick wall.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/24/2019 11:55 pm
Note however that in a fish or prawn farm (as opposed to an aquarium), the water turbidity mostly due to phytoplankton is extremely high, visibility optimally being about 30cm.

http://www.vietlinhjsc.com/en/aquaculture/water-turbidity.asp

Hence the filter feeders (shellfish). Their main diet is plankton, and a single one can filter ~150 gallons of water per day, all without the inefficiency of actually moving its body around. "Nothing left to take away."

Most aquaculture farms are very polluting and unhealthy environments, essentially just feedlots on the water. Very inefficient, and not the type of systems we want to be emulating imo.

You may have a roomba (or simpler) to loosen plankton from the walls, but the shellfish can filter it from the water column without further assistance.
Title: Re: Envisioning Amazing Martian Habitats
Post by: golosio on 04/25/2019 04:00 am
@Lampyridae nice post. About integrating windows with a real view on the outside, I think periscope windows could be an interesting solution. See
http://www.asi.org/adb/04/02/03/periscope-anecdote.html
I think from a psychological perspective it would be important that people living in Mars have houses that are similar to what they have on Earth, not necessarily better than than that. Trying to put together this need with radiation protection, cost and easy of implementation, I think a solution proposed by @Lampyridae, integrated with something as periscope windows, is one of the most interesting. I'm sure with this approach it would be possible to build houses that in the inside look very similar to what we have on Earth.
......
The thing that bugs me about this is that humans prefer a room with a view, and this doesn't provide one. Studies have shown that a hospital room looking out onto a nature scene speed recovery compared to one looking at a brick wall.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 04/25/2019 01:12 pm
Note however that in a fish or prawn farm (as opposed to an aquarium), the water turbidity mostly due to phytoplankton is extremely high, visibility optimally being about 30cm.

http://www.vietlinhjsc.com/en/aquaculture/water-turbidity.asp

Hence the filter feeders (shellfish). Their main diet is plankton, and a single one can filter ~150 gallons of water per day, all without the inefficiency of actually moving its body around. "Nothing left to take away."

Most aquaculture farms are very polluting and unhealthy environments, essentially just feedlots on the water. Very inefficient, and not the type of systems we want to be emulating imo.

You may have a roomba (or simpler) to loosen plankton from the walls, but the shellfish can filter it from the water column without further assistance.
When we had a fishtank we had a plecostomus that travelled the walls and cleaned them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/25/2019 05:53 pm
@Lampyridae nice post. About integrating windows with a real view on the outside, I think periscope windows could be an interesting solution. See
http://www.asi.org/adb/04/02/03/periscope-anecdote.html
I think from a psychological perspective it would be important that people living in Mars have houses that are similar to what they have on Earth, not necessarily better than than that. Trying to put together this need with radiation protection, cost and easy of implementation, I think a solution proposed by @Lampyridae, integrated with something as periscope windows, is one of the most interesting. I'm sure with this approach it would be possible to build houses that in the inside look very similar to what we have on Earth.
......
The thing that bugs me about this is that humans prefer a room with a view, and this doesn't provide one. Studies have shown that a hospital room looking out onto a nature scene speed recovery compared to one looking at a brick wall.

I think it should be possible to have rooms with fantastic views and minimal radiation hazards. The things to avoid are windows looking directly up, windows through which the sun is directly visible or windows which look out upon high angles of the sky.

A window looking north with radiation shielding directly above it and overhanging the window could provide very spectacular views in reflected light. Radiation from the sun would be blocked and cosmic radiation would be greatly reduced as it would only come from a relatively narrow angle from the horizon and just above and would have to pass through a much thicker layer of Martian atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: golosio on 04/25/2019 09:05 pm
[
I think it should be possible to have rooms with fantastic views and minimal radiation hazards. The things to avoid are windows looking directly up, windows through which the sun is directly visible or windows which look out upon high angles of the sky.

A window looking north with radiation shielding directly above it and overhanging the window could provide very spectacular views in reflected light. Radiation from the sun would be blocked and cosmic radiation would be greatly reduced as it would only come from a relatively narrow angle from the horizon and just above and would have to pass through a much thicker layer of Martian atmosphere.

If you talk about windows next to which you can go occasionally to take a look outside, wearing personal dosimeter and taking care not to exceed the dose limits, I agree. However I'm afraid you could not have this kind of windows a few meters from you in your office, or in your bedroom, or in any place where you spend a significant part of your time.
Although such windows could give good protection from ionizing solar radiation, a significant fraction of ionizing radiation on Mars surface is due to galactic cosmic rays (primary GCR or secondary particles generated by their interaction with the atmosphere or with the surface). As you know, Martian atmosphere is very rarefied, with a density on the surface of about 2% of that of the earth.
Particles coming from just 30 degrees above the horizon must pass through a thickness of atmosphere that is only about two times greater than the vertical one, too small to have a significant reduction in radiation intensity. Furthermore, we must take into account the secondary radiation scattered by the walls of the cavity in which the window is located....
@Lampyridae posted an image of a semi-buried dome with numbers for equivalent dose per day. As you can see, the equivalent dose close to the ice wall, with two-meters-ice shielding, is as high as 0.33 mSv/day, and this is without a hole for a window....
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/25/2019 10:15 pm
[
I think it should be possible to have rooms with fantastic views and minimal radiation hazards. The things to avoid are windows looking directly up, windows through which the sun is directly visible or windows which look out upon high angles of the sky.

A window looking north with radiation shielding directly above it and overhanging the window could provide very spectacular views in reflected light. Radiation from the sun would be blocked and cosmic radiation would be greatly reduced as it would only come from a relatively narrow angle from the horizon and just above and would have to pass through a much thicker layer of Martian atmosphere.

If you talk about windows next to which you can go occasionally to take a look outside, wearing personal dosimeter and taking care not to exceed the dose limits, I agree. However I'm afraid you could not have this kind of windows a few meters from you in your office, or in your bedroom, or in any place where you spend a significant part of your time.
Although such windows could give good protection from ionizing solar radiation, a significant fraction of ionizing radiation on Mars surface is due to galactic cosmic rays (primary GCR or secondary particles generated by their interaction with the atmosphere or with the surface). As you know, Martian atmosphere is very rarefied, with a density on the surface of about 2% of that of the earth.
Particles coming from just 30 degrees above the horizon must pass through a thickness of atmosphere that is only about two times greater than the vertical one, too small to have a significant reduction in radiation intensity. Furthermore, we must take into account the secondary radiation scattered by the walls of the cavity in which the window is located....
@Lampyridae posted an image of a semi-buried dome with numbers for equivalent dose per day. As you can see, the equivalent dose close to the ice wall, with two-meters-ice shielding, is as high as 0.33 mSv/day, and this is without a hole for a window....
So, it’s worse than I thought. It would need to be a north facing window with no view to the sky. But it could still be a spectacular view though with mountains, canyon walls etc
Title: Re: Envisioning Amazing Martian Habitats
Post by: golosio on 04/25/2019 10:46 pm
So, it’s worse than I thought. It would need to be a north facing window with no view to the sky. But it could still be a spectacular view though with mountains, canyon walls etc
Yes, it would be really a spectacular view! I would like to be on Mars to see it :D However I think you should not underestimate the possibilities of periscope windows, see my previous post. After all, they would show the real image of the outside, just with a couple of reflections and some optics, they could have relatively wide viewing angle, and be safe in terms of radiation protection. And I think it could be possible to make them look as real conventional windows.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/25/2019 10:53 pm
So, it’s worse than I thought. It would need to be a north facing window with no view to the sky. But it could still be a spectacular view though with mountains, canyon walls etc
Yes, it would be really a spectacular view! I would like to be on Mars to see it :D However I think you should not underestimate the possibilities of periscope windows, see my previous post. After all, they would show the real image of the outside, just with a couple of reflections and some optics, they could have relatively wide viewing angle, and be safe in terms of radiation protection. And I think it could be possible to make them look as real conventional windows.
Yes sounds like a plan and perhaps add a few plain open sky windows as well (limited stay & dosimeters required). Room for them all I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 04/25/2019 11:37 pm
People underestimate just how good of a job the Martian atmosphere does at least at lower altitudes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/26/2019 04:49 am
This discussion perfectly illustrates why I think huge windows will be extravagant conspicuously consumed luxury items for the rich. Much more trouble than they're worth. Cover the building with regolith and be done with it.

From a strictly dollars-to-donuts perspective, you get to live/work on frikkin' Mars. If you don't fancy the interior decoration scheme, there's a line of less-picky bodies out the door eager to take your slot.

The ultra-rich will demand huge windows (and pay handsomely for the privilege), but no one else will be in a position to afford them (heck, this is true even on Earth where huge windows are much cheaper). That's why I expect large windows will be either communally-funded or patron-funded.


My favourite shape for above ground is cylindrical skyscrapers.
* Good shielding for all but top levels because radiation from the side has to pass through a lot more layers.

Isn't this exactly the opposite though? A tall skinny skyscraper is the worst possible shape from a shielding perspective, because the exposed-surface-area to volume ratio is so high.

What you want is literally the exact opposite philosophy: wide long "warehouse" buildings. That way in most modules you only have to shield on one side (the roof) not five sides (the roof plus four walls). Obviously the perimeter will still need wall shielding, but the bigger you scale the building the less perimeter-per-area there is.

* Unlike a dome you can keep extending it, probably to impressive heights on Mars.

A simple rectangular building on flat ground is even easier to keep extending. Just build the next building right beside it, merging the roof shields together (so you can delete the unneeded shielding walls on both sides). This has the advantage that the first building does not have to hold up the weight of the second building. Ditto for the radiation shielding.


You may have a roomba (or simpler) to loosen plankton from the walls, but the shellfish can filter it from the water column without further assistance.
When we had a fishtank we had a plecostomus that travelled the walls and cleaned them.

Precisely! I was thinking either the roomba, that, or just manual cleaning. Whichever ends up being cheaper (and the 'right' answer won't even necessarily be the same in all scenarios).



A pressure vessel on Mars would need the following:

1. Top dome reinforcement to deal with regolith shield load
2. Sidewall reinforcement to carry load and deal with potential buckling

This reinforcement needn't add any extra mass. Obviously the vertical tensile members can be shaped as hollow steel sections or I-beam columns of appropriate dimensions, which are resistant to compressive buckling despite having no mass penalty in tension.

Of course, you can just sandbag an arch all the way over the top of the pressure vessel, but that gets difficult when it's 6m and you need a minimum of 1.5m for any benefit.

Sorry, I'm confused. What is 6 meters?

Of course, if you just pile regolith around a habitat, you actually screen more radiation than if you piled it on top, because only 30% of the sky hemisphere is above 45 degrees.

That assumes hab dimensions are roughly equal in the X, Y, and Z dimensions (length/width/height). Obviously this is not necessarily (or even ideally) the case. Per-volume hab shielding costs are minimized if X, Y >> Z.

Here's some examples of how habitats could be buried: semi-exposed, semi-exposed with embankments and of course fully buried. But semi-exposed with embankments gives pretty good radiation shielding in conjunction with a reasonable water ice shield on top. (2m cuts by 50%, 3m cuts by 70%...)

Exactly my thinking, except replace the expensive water ice and its anti-sublimation containment system with cheap readily-available regolith sandbags. Water will be in high demand for other purposes (read: expensive).

Also regolith can be stable at room temperature, so the massive shield can be located inside the thermal envelope to provide a thermal mass battery. The low operating temperature of water ice introduces (solvable!) design problems that simply disappear if you switch to regolith.

And of course make the building long and wide, so the perimeter to area ratio is lower, so the per square meter embankment cost is lower.

Just arrange the internals so that loitering in radiation hot spots is discouraged or prevented, eg with a nice vertical hydroponic garden in the centre.

Indeed, gardens seem almost purpose-built to encourage loitering. ;D

The thing that bugs me about this is that humans prefer a room with a view, and this doesn't provide one. Studies have shown that a hospital room looking out onto a nature scene speed recovery compared to one looking at a brick wall.

Seems possible to provide many of the psychological benefits of that "nature scene" with an indoor Earthship-style garden/arboretum. Outdoor conditions on Mars will be a barren inhospitable desert. These I presume were not the outdoor conditions in the hospital room study (studies?) you mention.

Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 04/26/2019 04:53 am
[
I think it should be possible to have rooms with fantastic views and minimal radiation hazards. The things to avoid are windows looking directly up, windows through which the sun is directly visible or windows which look out upon high angles of the sky.

A window looking north with radiation shielding directly above it and overhanging the window could provide very spectacular views in reflected light. Radiation from the sun would be blocked and cosmic radiation would be greatly reduced as it would only come from a relatively narrow angle from the horizon and just above and would have to pass through a much thicker layer of Martian atmosphere.

If you talk about windows next to which you can go occasionally to take a look outside, wearing personal dosimeter and taking care not to exceed the dose limits, I agree. However I'm afraid you could not have this kind of windows a few meters from you in your office, or in your bedroom, or in any place where you spend a significant part of your time.
Although such windows could give good protection from ionizing solar radiation, a significant fraction of ionizing radiation on Mars surface is due to galactic cosmic rays (primary GCR or secondary particles generated by their interaction with the atmosphere or with the surface). As you know, Martian atmosphere is very rarefied, with a density on the surface of about 2% of that of the earth.
Particles coming from just 30 degrees above the horizon must pass through a thickness of atmosphere that is only about two times greater than the vertical one, too small to have a significant reduction in radiation intensity. Furthermore, we must take into account the secondary radiation scattered by the walls of the cavity in which the window is located....
@Lampyridae posted an image of a semi-buried dome with numbers for equivalent dose per day. As you can see, the equivalent dose close to the ice wall, with two-meters-ice shielding, is as high as 0.33 mSv/day, and this is without a hole for a window....
So, it’s worse than I thought. It would need to be a north facing window with no view to the sky. But it could still be a spectacular view though with mountains, canyon walls etc

Especially if your window is high up the southern wall of one of the large chasma.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/26/2019 08:21 am
People underestimate just how good of a job the Martian atmosphere does at least at lower altitudes.

Yes and no... and yes. Below 45 degrees it offers no additional effect due to the Pfötzer maximum (50 to 200g/cm2), until about 5 degrees above the horizon where the optical depth starts increasing very rapidly to a maximum of about 450g/cm2. That's enough to cut deep space GCR by 40%.

Reducing your elevation on Mars to -4km cuts radiation by about 15% (offhand - I can't access my OLTARIS results since it's down for maintenance).

At the horizon though, that extra 10g/cm2 overhead makes a huge difference. At 0km, you're only getting increased shielding benefits again at 5 degrees. At -4km, that's now starting at 8 degrees.
Title: Re: Envisioning Amazing Martian Habitats
Post by: golosio on 04/26/2019 08:48 am
@Twark_Main very good post! I agree with almost everything. The only remark I would make is that the fact that a place is inhospitable does not mean that it is not beautiful. There are many inhospitable places on Earth that are really beautiful. On this I agree with @Slarty1080 and @MickQ : a view on Mars landscape would be spectacular, if I would live on Mars I would like to have such view. There is research work to find solutions that are compatible with radiation safety requirements, and personally I am optimistic that it is possible to find something affordable, not only for rich people.
Isn't this exactly the opposite though? A tall skinny skyscraper is the worst possible shape from a shielding perspective, because the exposed-surface-area to volume ratio is so high.
Technically speaking, not the worst possible but for sure not a good one from a shielding perspective  ;D
Seriously, you're right.

What you want is literally the exact opposite philosophy: wide long "warehouse" buildings. That way in most modules you only have to shield on one side (the roof) not five sides (the roof plus four walls). Obviously the perimeter will still need wall shielding, but the bigger you scale the building the less perimeter-per-area there is.

* Unlike a dome you can keep extending it, probably to impressive heights on Mars.

A simple rectangular building on flat ground is even easier to keep extending. Just build the next building right beside it, merging the roof shields together (so you can delete the unneeded shielding walls on both sides). This has the advantage that the first building does not have to hold up the weight of the second building. Ditto for the radiation shielding.
I agree

Exactly my thinking, except replace the expensive water ice and its anti-sublimation containment system with cheap readily-available regolith sandbags. Water will be in high demand for other purposes (read: expensive).
You are probably right, but it may depend on the site where the dome is built, and on ice availability in that site.

Seems possible to provide many of the psychological benefits of that "nature scene" with an indoor Earthship-style garden/arboretum. Outdoor conditions on Mars will be a barren inhospitable desert. These I presume were not the outdoor conditions in the hospital room study (studies?) you mention.
My proposal would be semi-buried apartments with windows on the inner garden on one side, telescope windows  viewing the Mars landscape on the other side, real windows with outside view in common controlled areas where people can go with a badge and personal dosimeter, more expensive/fancy things in common areas.
   
Title: Re: Envisioning Amazing Martian Habitats
Post by: CrazyHorse80 on 04/26/2019 10:05 am
Could it be possible to make a very large window by putting liquid water inside the gap between two glass sheets? Could it be effective enough for radiation shielding?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/26/2019 11:59 am
@Twark_Main very good post! I agree with almost everything. The only remark I would make is that the fact that a place is inhospitable does not mean that it is not beautiful. There are many inhospitable places on Earth that are really beautiful. On this I agree with @Slarty1080 and @MickQ : a view on Mars landscape would be spectacular, if I would live on Mars I would like to have such view. There is research work to find solutions that are compatible with radiation safety requirements, and personally I am optimistic that it is possible to find something affordable, not only for rich people.

I can imagine a future Cohagen not bothering to provide shielding. In Total Recall, Benny the taxi driver /  spy's line about "cheap domes" was quite relevant. The original Rob Cobb concept art had the colony town underneath regolith with windows and sun trackers very much like what we're discussing now. In fact, from Cohagen's office you can see the old domes Benny was talking about, before the colony mined out the canyon.



Windows are quite affordable: and necessary, not merely a luxury.

An enormous, floor-to-ceiling picture window that gives you a 90 degree field of view to glower over your colony* only accounts for some 17.25% of your dose. That's 0.12mSv a day if you never leave your office, and the window is unshielded. 0.04mSv if you work an 8 hour day there. Solar radiation is negligible. The dose can be cut further with a hydrogen-rich shield, such as acrylic. If you're a cruel dictator like Cohagen you sit with your back right up against the window and get exposed to more radiation, or maybe you can afford magnetic shielding because you saved on cheap domes. Richter is smart: he doesn't stand in the radiation "hot spot." Certain plastics could be doped with boron and gadolinium to further improve their neutron stopping power.

(https://2.bp.blogspot.com/-IiFsw5i0xhY/VgGE2bk9KGI/AAAAAAAABOA/lQ7i4NeW0dQ/s2048/09%2BMars%2Bcolony%2Band%2BCohagen%2BTotal%2BRecall%2B1990%2Bmovie%2Bimage.jpg)

Acrylic is fairly simple to produce from methane precursors, unlike polycarbonate. But even then, colonists can carry windows as cargo. A sealed 1m square 10cm thick acrylic window mounted on a cabin wall is a fantastic way to beef up a passenger's shielding in transit.

But, on Mars water is cheap and transparent. 7.5 tonnes of water will fill a 0.5m thick, 2.5m high, 6m wide Cohagen window. But you don't want it to slope backwards because you are exposing yourself a bit to the overhead radiation. Rather, simply slope it forwards. That way it preferentially intercepts the least-protected radiation segment. With such an arrangment you could sit with your back to your Mars colony and intimidate underlings appropriately.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 04/26/2019 09:45 pm
They also originally envisioned huge helicopter-like plexiglass windows on the Lunar (Excursion) Module. However, by the time that the LEM was renamed the LM they realised that in low gravity you may as well stand up with your face close to a small window than sit down further removed from a large window.

I suspect the same could be the case on Mars. At 1/3 Earth gravity it will be very pleasant to stand with your face close to a perfectly serviceable 10x20 cm. window overlooking the Martian landscape.

As for wall art, roll-up'able 8K OLED displays showing a live view of the Martian surface will surely be a big hit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/27/2019 12:57 am
Too many windows?
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 04/27/2019 01:00 am
How long do you suppose artificial grass would still look good on Mars?
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 04/27/2019 06:25 am
My favourite shape for above ground is cylindrical skyscrapers.
* Good shielding for all but top levels because radiation from the side has to pass through a lot more layers.

Isn't this exactly the opposite though? A tall skinny skyscraper is the worst possible shape from a shielding perspective, because the exposed-surface-area to volume ratio is so high.

What you want is literally the exact opposite philosophy: wide long "warehouse" buildings. That way in most modules you only have to shield on one side (the roof) not five sides (the roof plus four walls). Obviously the perimeter will still need wall shielding, but the bigger you scale the building the less perimeter-per-area there is.

* Unlike a dome you can keep extending it, probably to impressive heights on Mars.

A simple rectangular building on flat ground is even easier to keep extending. Just build the next building right beside it, merging the roof shields together (so you can delete the unneeded shielding walls on both sides). This has the advantage that the first building does not have to hold up the weight of the second building. Ditto for the radiation shielding.
No my argument is that a tall tower gives the best shielding on mars because most of the radiation comes from above rather than from the horizon due to the atmosphere being much thicker in the horizontal direction. Just put your water cistern etc on the top, and have windows say a foot thick, which could create a couple of meters of shielding for cosmic rays coming in at a steep slant.

Not only is it best shielding per volume, but best shielding per viewing area. A cylindrical tower gives you level after level of good viewing area to look out over the martian vista. A dome would only give you a few good levels for looking out on the terrain, and often obstructed by other infrastructure on the ground.  A low rectangular grid of buildings would give you the lowest proportion of viewing area due to most obstruction by surrounding buildings, and the least volume per shielding mass.

Im not saying grids are not useful for other purposes, but my assumption was a mostly underground city with above ground habitable areas specifically to provide views of mars itself, all the way to the horizon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/27/2019 01:11 pm
No my argument is that a tall tower gives the best shielding on mars because most of the radiation comes from above rather than from the horizon due to the atmosphere being much thicker in the horizontal direction. Just put your water cistern etc on the top, and have windows say a foot thick, which could create a couple of meters of shielding for cosmic rays coming in at a steep slant.

At 45° to the horizon, the path through the atmosphere is only 40% more than a path straight down. At 30° to the horizon, it's only double. Even at just 15° above the horizon, it's only 4 times the vertical path.

In addition, the secondary radiation created by impacting cosmic rays will be virtually isotropic, with a heightened backscatter from the ground.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/27/2019 02:23 pm
Could it be possible to make a very large window by putting liquid water inside the gap between two glass sheets? Could it be effective enough for radiation shielding?
Large glass windows will break under the atmospheric pressure from the interior unless they are extremely thick, rather like the large tanks in public aquarium but even more so.  The interior pressure is usually planned a 10 tonnes per m2.
One of the ways to reduce the strain on the glass is to subdivide it into smaller window panes supported by a strong metal structure.  Like in the joined image.  Almost all of the strain in on the metal rather than on the glass.
It does break up the view though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/27/2019 02:28 pm
How long do you suppose artificial grass would still look good on Mars?
Outside or inside?  Outside it would get dirty within the year.  Inside, well it's a question of taste but it never really looks good, does it?
Green walls and herb gardens are more work, but should be more useful.  And artificial grass is plastic, and that is surprisingly expensive on Mars, because it is essentially the product of water electrolysis, one of the most energy intensive process there is. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/27/2019 03:39 pm
As far as exposure goes, does the following make sense?
-Martian background average radiation is 240-300 mSv per year (if anyone has another number and reference would love to have it).
-If you sleep in a radiation shielded space, 8/24, then the dose would be 160-200 mSv per year.
-If you do most of your living (work, study) in a radiation shielded space then your dose becomes 80 to 100 mSv.
-If 50% of the radiation in space with outside windows is stopped by geometries, than the dose is down to 40 to 50 mSv.  this is the average worker radiation per year, but about twice the 20 mSv per year for a 5 year period.
-Part of the surface dose on Mars is solar proton events.  These are predictable, and a large colony will mostly be protected.  So during Solar Proton Events you should stay away from the windows.
-What is the portion of the dosage from SPE?  I have a weak reference that puts this at 30%.  If correct, then the radiation load from large windows under a radiation proof ceiling is acceptable.
-Mars should be low in Radon because it is low in Thorium.  As 2 mSv on Earth comes from atmospheric radon, then this part of the yearly dose goes away.
-Does 1/2 to 1 inches of glass have any effect on radiation dosage?

If the above is correct, then large windows are not really an issue.  Geodesic glass domes over public spaces might be a poor choice, unless there is an understanding that you don't spend more than 2 to 4 hours per day under them.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 04/27/2019 04:39 pm
As far as exposure goes, does the following make sense?
-Martian background average radiation is 240-300 mSv per year (if anyone has another number and reference would love to have it).
-If you sleep in a radiation shielded space, 8/24, then the dose would be 160-200 mSv per year.
-If you do most of your living (work, study) in a radiation shielded space then your dose becomes 80 to 100 mSv.
-If 50% of the radiation in space with outside windows is stopped by geometries, than the dose is down to 40 to 50 mSv.  this is the average worker radiation per year, but about twice the 20 mSv per year for a 5 year period.
-Part of the surface dose on Mars is solar proton events.  These are predictable, and a large colony will mostly be protected.  So during Solar Proton Events you should stay away from the windows.
-What is the portion of the dosage from SPE?  I have a weak reference that puts this at 30%.  If correct, then the radiation load from large windows under a radiation proof ceiling is acceptable.
-Mars should be low in Radon because it is low in Thorium.  As 2 mSv on Earth comes from atmospheric radon, then this part of the yearly dose goes away.
-Does 1/2 to 1 inches of glass have any effect on radiation dosage?

If the above is correct, then large windows are not really an issue.  Geodesic glass domes over public spaces might be a poor choice, unless there is an understanding that you don't spend more than 2 to 4 hours per day under them.

While I don't have anything to add for the numbers, you make a good point here regarding veiws and windows.
If the whole colony is heavily sheilded, it may be acceptable to have several areas where you can allow for large open, dome-like spaces as long as this isn't the main area you live in.

While you would still be exposed to more radiation, this would drop your net dosage down to an acceptable level.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/27/2019 05:25 pm
My favourite shape for above ground is cylindrical skyscrapers.
* Good shielding for all but top levels because radiation from the side has to pass through a lot more layers.

Isn't this exactly the opposite though? A tall skinny skyscraper is the worst possible shape from a shielding perspective, because the exposed-surface-area to volume ratio is so high.

What you want is literally the exact opposite philosophy: wide long "warehouse" buildings. That way in most modules you only have to shield on one side (the roof) not five sides (the roof plus four walls). Obviously the perimeter will still need wall shielding, but the bigger you scale the building the less perimeter-per-area there is.

* Unlike a dome you can keep extending it, probably to impressive heights on Mars.

A simple rectangular building on flat ground is even easier to keep extending. Just build the next building right beside it, merging the roof shields together (so you can delete the unneeded shielding walls on both sides). This has the advantage that the first building does not have to hold up the weight of the second building. Ditto for the radiation shielding.
No my argument is that a tall tower gives the best shielding on mars because most of the radiation comes from above rather than from the horizon due to the atmosphere being much thicker in the horizontal direction. Just put your water cistern etc on the top, and have windows say a foot thick, which could create a couple of meters of shielding for cosmic rays coming in at a steep slant.

Not only is it best shielding per volume

Sorry, but no it isn't.

That would make sense if the radiation came from a point source at the zenith, but it doesn't. In reality the water cistern will provide some radiation "shadow" for the core of the top few floors, but that's it.

You're left with a small footprint shape, which means a small area-to-perimeter ratio. Lots of vertical walls, (also imo these massive self-supporting or building-supported walls will be more expensive per-kg than a simple loose regolith roof, but that's separate from the main geometric argument). Therefore your shielding walls+roof will be much more massive (per volume!) for a skyscraper-shaped building than for a warehouse-shaped building.



A low rectangular grid of buildings would give you... the least volume per shielding mass.

Again this is not so.

Thought experiment: take your existing skyscraper, delete all the shielding walls, and pack many towers tightly together on a grid. Now re-add the shielding walls, but only on the perimeter (a huge per-volume cost savings!). You now have at least as good, if not much greater radiation shielding protection (all building locations are now as shielded as much as the most-shielded location, ie someone huddled right below the radiation shielding water cistern), while simultaneously using vastly less shielding mass.

Do you see now why a skyscraper can't possibly be as efficient per volume?

Im not saying grids are not useful for other purposes, but my assumption was a mostly underground city with above ground habitable areas specifically to provide views of mars itself, all the way to the horizon.

I did specifically bring up this (imo rather depressing) possibility. But I want real, honest-to-God above ground buildings, not just scenic outcroppings for mole people. Different folks, different strokes. :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/27/2019 06:29 pm
As far as exposure goes, does the following make sense?
-Martian background average radiation is 240-300 mSv per year (if anyone has another number and reference would love to have it).
-If you sleep in a radiation shielded space, 8/24, then the dose would be 160-200 mSv per year.
-If you do most of your living (work, study) in a radiation shielded space then your dose becomes 80 to 100 mSv.
-If 50% of the radiation in space with outside windows is stopped by geometries, than the dose is down to 40 to 50 mSv.  this is the average worker radiation per year, but about twice the 20 mSv per year for a 5 year period.
-Part of the surface dose on Mars is solar proton events.  These are predictable, and a large colony will mostly be protected.  So during Solar Proton Events you should stay away from the windows.
-What is the portion of the dosage from SPE?  I have a weak reference that puts this at 30%.  If correct, then the radiation load from large windows under a radiation proof ceiling is acceptable.
-Mars should be low in Radon because it is low in Thorium.  As 2 mSv on Earth comes from atmospheric radon, then this part of the yearly dose goes away.
-Does 1/2 to 1 inches of glass have any effect on radiation dosage?

If the above is correct, then large windows are not really an issue.  Geodesic glass domes over public spaces might be a poor choice, unless there is an understanding that you don't spend more than 2 to 4 hours per day under them.

Radon is unlikely to cause problems on Mars (unlike on Earth where it is the second most frequent cause of lung cancer, after cigarette smoking, causing an estimated 21,000 lung cancer deaths per year in the United States.) But not because of low Thorium levels.

A Mars base would be sealed from the Martian environment with a very large positive pressure so no atmospheric gases would leak in. The internal atmosphere would be continuously recycled and only need small top ups. These top ups could introduce Radon gas, but if the top up gases were to be stored for a few weeks prior to being used the vast majority of any Radon present would have decayed as the most stable isotope 222Rn only has a half-life of 3.82 days.

222Rn is formed in the decay series from 238U that involves two isotopes of Thorium which are both relatively short lived so high concentrations of Thorium are not necessary for high levels of Radon.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 04/27/2019 08:38 pm
If you’re using Windows, you’d use polycarbonate instead of glass. Much better at absorbing radiation without as much possibility of brittle failure. Can also invisibly bond several pieces together in a seamless vista. Strength is high, too. Already used for aquariums on Earth with similar or higher pressure differentials and similar safety requirements.
http://www.reynoldspolymer.com/sites/default/files/Acrylic%20in%20Modern%20Aquarium%20Exhibits.pdf

15 inch thicknesses aren’t too uncommon, and you can get thinner or thicker.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/27/2019 09:33 pm
Too many windows?

Nope that's fine. If you are standing at one window, with a low slab over you, you are basically shielded by the entire slab. The windows behind you only let through rays that have already passed through a significant amount of atmosphere. You could also play tricks with daylight coatings to project the swlight where you want inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/27/2019 09:39 pm
As far as exposure goes, does the following make sense?
-Martian background average radiation is 240-300 mSv per year (if anyone has another number and reference would love to have it).
-If you sleep in a radiation shielded space, 8/24, then the dose would be 160-200 mSv per year.
-If you do most of your living (work, study) in a radiation shielded space then your dose becomes 80 to 100 mSv.
-If 50% of the radiation in space with outside windows is stopped by geometries, than the dose is down to 40 to 50 mSv.  this is the average worker radiation per year, but about twice the 20 mSv per year for a 5 year period.
-Part of the surface dose on Mars is solar proton events.  These are predictable, and a large colony will mostly be protected.  So during Solar Proton Events you should stay away from the windows.
-What is the portion of the dosage from SPE?  I have a weak reference that puts this at 30%.  If correct, then the radiation load from large windows under a radiation proof ceiling is acceptable.
-Mars should be low in Radon because it is low in Thorium.  As 2 mSv on Earth comes from atmospheric radon, then this part of the yearly dose goes away.
-Does 1/2 to 1 inches of glass have any effect on radiation dosage?

If the above is correct, then large windows are not really an issue.  Geodesic glass domes over public spaces might be a poor choice, unless there is an understanding that you don't spend more than 2 to 4 hours per day under them.




Glass does cut down on radiation, substituting for an equivalent atmospheric mass but you want boron in it (pyrex) to help deal with neutrons.

As mentioned, polycarb or other thick plastic is your friend here. If you want an actual geodesic dome, you could heavily shield the houses and offices inside it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: golosio on 04/27/2019 10:18 pm
As far as exposure goes, does the following make sense?
-Martian background average radiation is 240-300 mSv per year (if anyone has another number and reference would love to have it).
-If you sleep in a radiation shielded space, 8/24, then the dose would be 160-200 mSv per year.
-If you do most of your living (work, study) in a radiation shielded space then your dose becomes 80 to 100 mSv.
-If 50% of the radiation in space with outside windows is stopped by geometries, than the dose is down to 40 to 50 mSv.  this is the average worker radiation per year, but about twice the 20 mSv per year for a 5 year period.
-Part of the surface dose on Mars is solar proton events.  These are predictable, and a large colony will mostly be protected.  So during Solar Proton Events you should stay away from the windows.
-What is the portion of the dosage from SPE?  I have a weak reference that puts this at 30%.  If correct, then the radiation load from large windows under a radiation proof ceiling is acceptable.
-Mars should be low in Radon because it is low in Thorium.  As 2 mSv on Earth comes from atmospheric radon, then this part of the yearly dose goes away.
-Does 1/2 to 1 inches of glass have any effect on radiation dosage?

If the above is correct, then large windows are not really an issue.  Geodesic glass domes over public spaces might be a poor choice, unless there is an understanding that you don't spend more than 2 to 4 hours per day under them.

Your dose estimates are reasonable, however unfortunately you cannot consider the radiation dose limit for workers as an acceptable level for someone who stays close to a window.
In Europe occupational exposure is ruled by directive  2013/59/EURATOM. I'm sure there are similar laws in the US. A fundamental principle of this directive is stated in article 5 (General principles of radiation protection):
"Member States shall establish legal requirements and an appro­priate regime of regulatory control which, for all exposure situ­ations, reflect a system of radiation protection based on the principles of justification, optimisation and dose limitation:
(a) Justification: Decisions introducing a practice shall be justified in the sense that such decisions shall be taken
with the intent to ensure that the individual or societal benefit resulting from the practice outweighs the health
detriment that it may cause. Decisions introducing or altering an exposure pathway for existing and emergency
exposure situations shall be justified in the sense that they should do more good than harm.
(b) Optimisation: Radiation protection of individuals subject to public or occupational exposure shall be optimised with the
aim of keeping the magnitude of individual doses, the like­lihood of exposure and the number of individuals exposed
as low as reasonably achievable taking into account the current state of technical knowledge and economic and
societal factors. ..."
For radiation exposure not related to work or to medical examination, an acceptable level is something comparable to Earth natural radiation background. You may agree or not agree, but these are the laws, and an engineer that design a house must take them into account, even if the house is on Mars, unless for some reason there will be special regulations on Mars different from those on Earth....
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/28/2019 02:21 am
As far as exposure goes, does the following make sense?
-Martian background average radiation is 240-300 mSv per year (if anyone has another number and reference would love to have it).
-If you sleep in a radiation shielded space, 8/24, then the dose would be 160-200 mSv per year.
-If you do most of your living (work, study) in a radiation shielded space then your dose becomes 80 to 100 mSv.
-If 50% of the radiation in space with outside windows is stopped by geometries, than the dose is down to 40 to 50 mSv.  this is the average worker radiation per year, but about twice the 20 mSv per year for a 5 year period.
-Part of the surface dose on Mars is solar proton events.  These are predictable, and a large colony will mostly be protected.  So during Solar Proton Events you should stay away from the windows.
-What is the portion of the dosage from SPE?  I have a weak reference that puts this at 30%.  If correct, then the radiation load from large windows under a radiation proof ceiling is acceptable.
-Mars should be low in Radon because it is low in Thorium.  As 2 mSv on Earth comes from atmospheric radon, then this part of the yearly dose goes away.
-Does 1/2 to 1 inches of glass have any effect on radiation dosage?

If the above is correct, then large windows are not really an issue.  Geodesic glass domes over public spaces might be a poor choice, unless there is an understanding that you don't spend more than 2 to 4 hours per day under them.

Your dose estimates are reasonable, however unfortunately you cannot consider the radiation dose limit for workers as an acceptable level for someone who stays close to a window.
In Europe occupational exposure is ruled by directive  2013/59/EURATOM. I'm sure there are similar laws in the US. A fundamental principle of this directive is stated in article 5 (General principles of radiation protection):
"Member States shall establish legal requirements and an appro­priate regime of regulatory control which, for all exposure situ­ations, reflect a system of radiation protection based on the principles of justification, optimisation and dose limitation:
(a) Justification: Decisions introducing a practice shall be justified in the sense that such decisions shall be taken
with the intent to ensure that the individual or societal benefit resulting from the practice outweighs the health
detriment that it may cause. Decisions introducing or altering an exposure pathway for existing and emergency
exposure situations shall be justified in the sense that they should do more good than harm.
(b) Optimisation: Radiation protection of individuals subject to public or occupational exposure shall be optimised with the
aim of keeping the magnitude of individual doses, the like­lihood of exposure and the number of individuals exposed
as low as reasonably achievable taking into account the current state of technical knowledge and economic and
societal factors. ..."
For radiation exposure not related to work or to medical examination, an acceptable level is something comparable to Earth natural radiation background. You may agree or not agree, but these are the laws, and an engineer that design a house must take them into account, even if the house is on Mars, unless for some reason there will be special regulations on Mars different from those on Earth....
Suddenly, I feel more sympathetic to Brexit  ;)

Going to Mars is not really a reasonable endeavor.  I think the pioneers will be signing a waiver as far as their health goes.  And they can make their own decisions.  And they will make the windows as thick as they think is required. The radiation risk will be weighted against the mental health risk, I expect.  In a sense.

However, their children, born on Mars, will require the best environment possible.  That may involve extra radiation risk, or it may not.  You would hope the Mars they make is a better place than the Earth, or else what's the point, really?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 04/28/2019 02:23 am
Of course Mars will have different regulations than on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 04/28/2019 10:20 am
As far as exposure goes, does the following make sense?
-Martian background average radiation is 240-300 mSv per year (if anyone has another number and reference would love to have it).
-If you sleep in a radiation shielded space, 8/24, then the dose would be 160-200 mSv per year.
-If you do most of your living (work, study) in a radiation shielded space then your dose becomes 80 to 100 mSv.
-If 50% of the radiation in space with outside windows is stopped by geometries, than the dose is down to 40 to 50 mSv.  this is the average worker radiation per year, but about twice the 20 mSv per year for a 5 year period.
-Part of the surface dose on Mars is solar proton events.  These are predictable, and a large colony will mostly be protected.  So during Solar Proton Events you should stay away from the windows.
-What is the portion of the dosage from SPE?  I have a weak reference that puts this at 30%.  If correct, then the radiation load from large windows under a radiation proof ceiling is acceptable.
-Mars should be low in Radon because it is low in Thorium.  As 2 mSv on Earth comes from atmospheric radon, then this part of the yearly dose goes away.
-Does 1/2 to 1 inches of glass have any effect on radiation dosage?

If the above is correct, then large windows are not really an issue.  Geodesic glass domes over public spaces might be a poor choice, unless there is an understanding that you don't spend more than 2 to 4 hours per day under them.

Your dose estimates are reasonable, however unfortunately you cannot consider the radiation dose limit for workers as an acceptable level for someone who stays close to a window.
In Europe occupational exposure is ruled by directive  2013/59/EURATOM. I'm sure there are similar laws in the US. A fundamental principle of this directive is stated in article 5 (General principles of radiation protection):
"Member States shall establish legal requirements and an appro­priate regime of regulatory control which, for all exposure situ­ations, reflect a system of radiation protection based on the principles of justification, optimisation and dose limitation:
(a) Justification: Decisions introducing a practice shall be justified in the sense that such decisions shall be taken
with the intent to ensure that the individual or societal benefit resulting from the practice outweighs the health
detriment that it may cause. Decisions introducing or altering an exposure pathway for existing and emergency
exposure situations shall be justified in the sense that they should do more good than harm.
(b) Optimisation: Radiation protection of individuals subject to public or occupational exposure shall be optimised with the
aim of keeping the magnitude of individual doses, the like­lihood of exposure and the number of individuals exposed
as low as reasonably achievable taking into account the current state of technical knowledge and economic and
societal factors. ..."
For radiation exposure not related to work or to medical examination, an acceptable level is something comparable to Earth natural radiation background. You may agree or not agree, but these are the laws, and an engineer that design a house must take them into account, even if the house is on Mars, unless for some reason there will be special regulations on Mars different from those on Earth....
Suddenly, I feel more sympathetic to Brexit  ;)

Going to Mars is not really a reasonable endeavor.  I think the pioneers will be signing a waiver as far as their health goes.  And they can make their own decisions.  And they will make the windows as thick as they think is required. The radiation risk will be weighted against the mental health risk, I expect.  In a sense.

However, their children, born on Mars, will require the best environment possible.  That may involve extra radiation risk, or it may not.  You would hope the Mars they make is a better place than the Earth, or else what's the point, really?

You mentioned the B word once but I think you got away with it...

I think a lot of people are fed up with health and safety trumps everything mentality and those going to Mars might well include a lot of people who thought that way. No doubt they would come to an alternative standard that was more in keeping with life on Mars. After all a lot of people chose to smoke. Radiation Health and Safety standards are ultimately arbitrary regardless of how much analysis and political hot air are expended in creating them.



Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 04/28/2019 10:28 am
At 45° to the horizon, the path through the atmosphere is only 40% more than a path straight down. At 30° to the horizon, it's only double. Even at just 15° above the horizon, it's only 4 times the vertical path.

In addition, the secondary radiation created by impacting cosmic rays will be virtually isotropic, with a heightened backscatter from the ground.
Those numbers suggest to me you get a pretty good shielding factor. Above 45° is a lot less than half the sky, for example.
It might be worth me attempting some sort of integration of path lengths or similar.. but just thinking about it there is a bunch I would need to get my head around, such as how the distribution of cosmic ray energies affects the effectiveness. Double the shielding does not actually halve the radiation for example.

Even without that shielding advantage I think it would still be the most efficient shape for viewing area. Domes still suck except for looking at the sky, ignoring anchoring issues, and single-level buildings are at best as good for viewing as one level of a cylindrical tower, with a lot more mass/window area to shield the roof. The cylinder is also one of the most convenient shapes for modular construction. One basic square window frame can support all cylinder radii and height, assuming loops of cable to reenforce each level, and something like steel reenforced concrete pillars for the actual load bearing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Cheapchips on 04/28/2019 10:46 am
How long do you suppose artificial grass would still look good on Mars?

Lawn vacuuming robots?  :)

Artificial grass and even plants around buildings would be surreal in the Martian landscspe, but I quite like the aestetic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 04/28/2019 01:39 pm
Of course Mars will have different regulations than on Earth.
Absolutely, but perhaps there will be a standard that rates window assemblies as function or radiation dose per hour of exposure.  There might be rules defining no cheap low protection windows in daycare centers or sleeping quarters, for example.  There might be less requirements for windows where people are less likely to stay for long periods of time in front of the windows: certain types of skylights, for example.

If there is less radon in Martian habitats, and we bury them 10 m deep  and use high resolution TVs instead of windows, we might have less radiation than on Earth?
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 04/28/2019 04:59 pm
Of course Mars will have different regulations than on Earth.
Absolutely, but perhaps there will be a standard that rates window assemblies as function or radiation dose per hour of exposure.  There might be rules defining no cheap low protection windows in daycare centers or sleeping quarters, for example.  There might be less requirements for windows where people are less likely to stay for long periods of time in front of the windows: certain types of skylights, for example.

If there is less radon in Martian habitats, and we bury them 10 m deep  and use high resolution TVs instead of windows, we might have less radiation than on Earth?

Maybe there will be a tax on the area of real windows on Mars ...
And I like the idea of open to view greenhouses or even small gardens along the walkways. There are lots of ideas on the aesthetically pleasing use of plant life in science fiction of lunar, asteroid and space habitats. Or even Nuclear Winter underground survival habitats on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: golosio on 04/28/2019 05:31 pm
Of course Mars will have different regulations than on Earth.
Absolutely, but perhaps there will be a standard that rates window assemblies as function or radiation dose per hour of exposure.  There might be rules defining no cheap low protection windows in daycare centers or sleeping quarters, for example.  There might be less requirements for windows where people are less likely to stay for long periods of time in front of the windows: certain types of skylights, for example.

If there is less radon in Martian habitats, and we bury them 10 m deep  and use high resolution TVs instead of windows, we might have less radiation than on Earth?
If the thickness of the cover is sufficient to drastically reduce the ionizing radiation of cosmic and solar origin, yes, there should be less radiation than on Earth, because natural radionuclides are much less abundant in the rocks of Mars than in the Earth.
(in particular Radon is produced by the decay chain of Uranium 238, which is much less abundant on Mars than on Earth rocks).
Title: Re: Envisioning Amazing Martian Habitats
Post by: launchwatcher on 04/28/2019 06:02 pm
Of course Mars will have different regulations than on Earth.
Yep.   Regulations on radiation exposure on earth are generally concerned with occupational exposures above natural background,  so as written they're likely not applicable to Mars, where (at least until there are nuclear reactors, nuclear medicine facilities,etc.,) it's the background radiation that you have to worry about..

Further complicating matters,  background levels vary significantly from place to place on earth -- the average is around 2.5mSv/year, but there's a long tail to the distribution and there are apparently nontrivial populations exposed to 10x and more with no statistically distinguishable effects on health as a result.   

So it's not at all clear what the right radiation exposure target is...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/29/2019 02:32 pm
Direct views can be handled with periscopes, either vertical or horizontal.

Bright indoor light doesn't seem to help. What is needed is bright outdoor light, >1 000 Lux and probably at least 10 000 Lux. Something like the Lowline might work, but the lighting here looks jarring and nasty.

(http://thelowline.org/assets/images/about/project/carousel_hero/1.jpg)

(https://static01.nyt.com/images/2016/10/08/nyregion/08LOWLINE1/08LOWLINE1-superJumbo.jpg?quality=90&auto=webp)

A large, partially buried dome with metre-sized concrete cells filled with regolith (3 or 4 layers) could be lit with solar concentrators piped downward. Their efficiency is around 50%, and with 50% coverage on the dome outside that means 25% of the 40 000 or so Lux on Mars, for 10 000 Lux.

Something that is also important for protection against myopia in children is also having sufficiently low-light conditions, ie from deep twilight to starlight. I think that's something our very Health & Safety-focused civilisation is going to have a hard time accepting.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6181186/
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/29/2019 03:12 pm
Update: Musk's Mars colony still looks pretty much the same. That dome looks to be about 60m+ across. Polyhedrals are 15-25m.

(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=47144.0;attach=1558528;image)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/29/2019 03:17 pm
could be lit with solar concentrators piped downward. Their efficiency is around 50%

On Mars you can drop that by around another 40-60% during half the (Mars) year, and by 80% or worse during the rest of the year, due to the effect of dust in the atmosphere. (The former being the good season (tau<=1), the latter being the bad season (tau>1.5.))

Basically, 12 months where it barely works followed by 12 months where it doesn't work. Seems like a lot of effort for not much benefit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/29/2019 04:29 pm
could be lit with solar concentrators piped downward. Their efficiency is around 50%

On Mars you can drop that by around another 40-60% during half the (Mars) year, and by 80% or worse during the rest of the year, due to the effect of dust in the atmosphere. (The former being the good season (tau<=1), the latter being the bad season (tau>1.5.))

Basically, 12 months where it barely works followed by 12 months where it doesn't work. Seems like a lot of effort for not much benefit.
Solar concentrators are out for that reason, but simple "light pipes" that bounce all directions of light around until they eventually get to the habitat level is another matter. It doesn't matter that sunlight is being scattered across the entire sky, because you're bringing the entire sky down to the hab.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 04/29/2019 04:49 pm
but simple "light pipes" that bounce all directions of light around until they eventually get to the habitat level is another matter. It doesn't matter that sunlight is being scattered across the entire sky, because you're bringing the entire sky down to the hab.

Yes, but I'm not sure you could get 10,000 lumen through a thick regolith shield that way.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/29/2019 04:53 pm
but simple "light pipes" that bounce all directions of light around until they eventually get to the habitat level is another matter. It doesn't matter that sunlight is being scattered across the entire sky, because you're bringing the entire sky down to the hab.

Yes, but I'm not sure you could get 10,000 lumen through a thick regolith shield that way.
Any idea how this would work on a mirrored water tank?
http://berkeleyphysicsdemos.net/node/724
(Except instead of an illusionary coin, you have an illusionary skylight...)
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 04/29/2019 05:01 pm
This discussion perfectly illustrates why I think huge windows will be extravagant conspicuously consumed luxury items for the rich. Much more trouble than they're worth. Cover the building with regolith and be done with it.

From a strictly dollars-to-donuts perspective, you get to live/work on frikkin' Mars. If you don't fancy the interior decoration scheme, there's a line of less-picky bodies out the door eager to take your slot.

The ultra-rich will demand huge windows (and pay handsomely for the privilege), but no one else will be in a position to afford them (heck, this is true even on Earth where huge windows are much cheaper). That's why I expect large windows will be either communally-funded or patron-funded.

I don't disagree that external windows on Mars will be small, but I think your reasoning is off. Even the most squalid apartment blocks and Soviet stack-a-prol buildings had huge windows. Glass placed into a hole in the wall is cheaper than constructing the wall in most applications.  Windows only get expensive when structural modifications and engineering concerns come into play because of the size of the window.

Now on Mars, I figure we will see lots of subterranean, wide-open, and well-lit internal common spaces; and the apartments leading to them will have huge windows, or slide-back doors to let in light.

Lighting then becomes a communal asset, and can be engineered as such with a mix of reflected light from outside and artificial light inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 04/29/2019 05:44 pm
could be lit with solar concentrators piped downward. Their efficiency is around 50%

On Mars you can drop that by around another 40-60% during half the (Mars) year, and by 80% or worse during the rest of the year, due to the effect of dust in the atmosphere. (The former being the good season (tau<=1), the latter being the bad season (tau>1.5.))

Basically, 12 months where it barely works followed by 12 months where it doesn't work. Seems like a lot of effort for not much benefit.

40 000 lux is the rough aphelion/summer solstice limit. The usual 0.5 tau doesn't affect global insolation much but it has a big effect on beam vs. diffuse irradiance... which makes solar concentrators less effective.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 04/29/2019 05:48 pm
could be lit with solar concentrators piped downward. Their efficiency is around 50%

On Mars you can drop that by around another 40-60% during half the (Mars) year, and by 80% or worse during the rest of the year, due to the effect of dust in the atmosphere. (The former being the good season (tau<=1), the latter being the bad season (tau>1.5.))

Basically, 12 months where it barely works followed by 12 months where it doesn't work. Seems like a lot of effort for not much benefit.

40 000 lux is the rough aphelion/summer solstice limit. The usual 0.5 tau doesn't affect global insolation much but it has a big effect on beam vs. diffuse irradiance... which makes solar concentrators less effective.
Biparabolic mirrored skylights shouldnt affect the outside light levels much at all.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/02/2019 04:49 am
Biparabolic mirrored skylights shouldnt affect the outside light levels much at all.

I kept meaning to ask, what is it that you think that particular optical illusion would achieve for a Mars hab?

(https://cdn.instructables.com/F1P/QA51/J44FTMCJ/F1PQA51J44FTMCJ.LARGE.jpg) (https://cdn.instructables.com/F1P/QA51/J44FTMCJ/F1PQA51J44FTMCJ.LARGE.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/02/2019 07:04 am
I think @rakaydos is referring to something like this:

(http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg)

The problem with this is that solar concentrators can only collect beam sunlight. Diffuse light cannot be collected due to conservation of étendue. Basically whatever they illuminate cannot become brighter than whatever concentrators are "looking" at. In other words, no setting things on fire from moonlight. (https://what-if.xkcd.com/145/)

Having thought about it, the large amount of diffuse light on Mars makes tracking solar arrays less necessary and flat solar arrays simply rolled out on the ground more economical, especially if high tau is expected. Interestingly, twilight persists for a very long time on Mars, so very large arrays will still produce a useful amount of power which would take the load off the energy storage system a bit.

Diffuse light makes windows more efficient at internal lighting, and if you want to make the most of natural lighting, you have to use a transparent dome.

Diffuse light also turns out to have a benefit for agriculture: it illuminates the underside of leaves, making photosynthesis more efficient. This may have been mentioned in the Scaling Agriculture thread.

What we've seen so far of the Mars colony as per Musk is:
- Underground tunnelling (something I find strange but maybe it makes sense in a stainless steel way)
- Geodesic dome for recreation and sunlight
- Agriculture lit by LED in buried greenhouses
- Images however show angular structures with some kind of moveable panels and large slats over the windows
Title: Re: Envisioning Amazing Martian Habitats
Post by: whvholst on 05/02/2019 08:52 am
I see a lot of discussion about shielding against radiation. Which may be partially mitigated by creating an artificial magnetosphere. Some back-of-the-envelope calculation suggest that may be remarkably doable once Starship becomes available: https://medium.com/our-space/an-artificial-martian-magnetosphere-fd3803ea600c

I think his choice of nuclear as a power source is a bit odd given that a large solar thermal power plant could easily double as a sun shield for the electromagnet. Think of putting something like the Ivanpah solar power plant in Sol-Mars L1.

This might allow all of a sudden for frivolous things like transparent domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/02/2019 11:20 am
I see a lot of discussion about shielding against radiation. Which may be partially mitigated by creating an artificial magnetosphere. Some back-of-the-envelope calculation suggest that may be remarkably doable once Starship becomes available: https://medium.com/our-space/an-artificial-martian-magnetosphere-fd3803ea600c

I think his choice of nuclear as a power source is a bit odd given that a large solar thermal power plant could easily double as a sun shield for the electromagnet. Think of putting something like the Ivanpah solar power plant in Sol-Mars L1.

This might allow all of a sudden for frivolous things like transparent domes.

This is for a magnetosphere protecting the whole planet against the relatively weak solar wind. On the surface, Martian atmospheric shielding does that. In the long run, it would be nice not to have the solar wind generating albedo neutrons in the atmosphere, and there would be a feedback loop as thickening atmosphere further protects the surface.

https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmosphere.html

Also, Earth's magnetic shield doesn't protect against powerful heavy cosmic ray ions, and mostly deflects mid-range energy ones so that they take a longer run through the atmosphere. This is why Leadvill, Colorado has a higher cosmic ray flux than Bolivia near the equator.

Local magnetic shielding would work, but would need to be very powerful. Currently, even on a mass for mass basis, active radiation shielding does not offer any significant improvement over passive and of course is very expensive and needs to be shipped from Earth. Future technologies may enable more open structures with magnetic shielding, or some kind of widespread, very weak umbrella of very large dimensions to provide overall protection.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20190002579.pdf

I do want to point out that domes are not frivolous: if you want people to pay to come to live for years or maybe their whole lives on Mars, you need something attractive which will also keep them sane. To be perfectly blunt, psychological and social disorders can impact the colony immediately, whereas cancer is a problem that can be handled back on Earth. "Just suck it up" as some people suggest is not an acceptable solution. Visiting a completely unshielded dome for an hour a day works out to 10mSv/year which compares with the 5mSv/year background dose on Earth. The average American only spends 7% of their life (1hr 40 mins/day) outdoors anyway (which is probably spent walking around the concrete jungle).
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/02/2019 03:57 pm
I think @rakaydos is referring to something like this:

(http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg)


Same concept, but fixed in place, using the illusion to make meters of intervening radiation shielding "disapear" (the inside of the skylight would use a transparent shielding, like water) but not actually concentrating the light beyond martian Sol.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/02/2019 04:27 pm
Diffuse light... illuminates the underside of leaves, making photosynthesis more efficient.

Agree with everything you wrote, but for clarification: do you mean higher energy efficiency of photosynthesis itself (more kilocalories/day per PPF) or 'just' higher leaf utilization efficiency (more kilocalories/day per m^2 of leaf area)? Naturally both have their advantages.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/02/2019 04:52 pm
I do want to point out that domes are not frivolous: if you want people to pay to come to live for years or maybe their whole lives on Mars, you need something attractive which will also keep them sane. To be perfectly blunt, psychological and social disorders can impact the colony immediately, whereas cancer is a problem that can be handled back on Earth. "Just suck it up" as some people suggest is not an acceptable solution.

Sheesh. I think humans are a lot less psychologically flimsy than you're giving credit for. These are such First World Problems-level problems.

But let's ignore that can of worms and just say you're right. Why would it be the case that this psychological need can only be filled by standing in a big dome, rather than say by looking out (much cheaper) bay windows and corner lounge windows built into existing structures? What part of the human brain thinks, "man this is a great open vista of Mars, just like I'd see from a dome, but somehow the window is just not expensive enough!"  ???

To be even blunter: the flimsy people won't go to Mars. Simple as that. Just like immigrating to America, or moving West in a covered wagon. You need to calibrate everything for the most hardy 10-15% of humanity, not the most delicate. Caveat: as always, the richer someone is, the nicer surroundings they can afford, and the flimsier the actual person can be. ;D

Naturally things will slowly get nicer on Mars over the decades, but it will never become as easy/cheap as life on Earth. Leaching off of Earth's "free" biosphere (as long as that lasts :-\) is just too big a planetary competitive advantage.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/02/2019 07:31 pm
I do want to point out that domes are not frivolous: if you want people to pay to come to live for years or maybe their whole lives on Mars, you need something attractive which will also keep them sane. To be perfectly blunt, psychological and social disorders can impact the colony immediately, whereas cancer is a problem that can be handled back on Earth. "Just suck it up" as some people suggest is not an acceptable solution.

Sheesh. I think humans are a lot less psychologically flimsy than you're giving credit for. These are such First World Problems-level problems.

But let's ignore that can of worms and just say you're right. Why would it be the case that this psychological need can only be filled by standing in a big dome, rather than say by looking out (much cheaper) bay windows and corner lounge windows built into existing structures? What part of the human brain thinks, "man this is a great open vista of Mars, just like I'd see from a dome, but somehow the window is just not expensive enough!"  ???

To be even blunter: the flimsy people won't go to Mars. Simple as that. Just like immigrating to America, or moving West in a covered wagon. You need to calibrate everything for the most hardy 10-15% of humanity, not the most delicate. Caveat: as always, the richer someone is, the nicer surroundings they can afford, and the flimsier the actual person can be. ;D

Naturally things will slowly get nicer on Mars over the decades, but it will never become as easy/cheap as life on Earth. Leaching off of Earth's "free" biosphere (as long as that lasts :-\) is just too big a planetary competitive advantage.
And of course people may be tough when they set out and get tired out and flimsy with time, as we do all.
Flimsy is very difficult to define, really  :-)
I expect most people going to Mars will be well off, or at least have rich patrons.  The wild west analogies are not correct in general, IMHO, although it will be a frontier, it is such a ridiculously difficult one that it has to be techo supported to work at all.
I tend to see Mars as a really rich suburb, rather than a frontier town.  Rather like the movie Elysium, really.
My own take on domes is that they will be aesthetic and cultural elements, but not a primary habitat element.
Glass and steel are cheap, in a relative sense, but concrete with bright lights is even cheaper.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/02/2019 07:39 pm
I do not live in a First World Country, and some green,* open space is as much a necessity here as it is there. There are plenty of studies supporting this.

The idea of the iron-willed settler is a myth. Astronauts have mental health issues too, and they are probably the hardiest among us. Humans have psychological needs, simple as that. Furthermore, children are likely to be born a few decades in either by design or accident, and they will have psychological needs too.

A dome on Mars is safer than going outside in a spacesuit. It is safer and cheaper than going back to Earth for a breather. Bay windows are not the same as being in a separate, relatively open space. A transparent dome is basically a collection of windows. There is one on the ISS.

Finally, this is a SpaceX thread, and Musk is putting great big windows on his ships and also discusses the need for domes because he is a successful businessperson and knows how to get things done and pitch it to the public. Try as I might, I can't fault his (and his company's) logic other than "it's expensive." You are welcome to your opinion, but I do not agree.

*or some natural environment, which nevertheless has some kind of life
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/02/2019 08:40 pm
I do want to point out that domes are not frivolous: if you want people to pay to come to live for years or maybe their whole lives on Mars, you need something attractive which will also keep them sane. To be perfectly blunt, psychological and social disorders can impact the colony immediately, whereas cancer is a problem that can be handled back on Earth. "Just suck it up" as some people suggest is not an acceptable solution.

Sheesh. I think humans are a lot less psychologically flimsy than you're giving credit for. These are such First World Problems-level problems.

But let's ignore that can of worms and just say you're right. Why would it be the case that this psychological need can only be filled by standing in a big dome, rather than say by looking out (much cheaper) bay windows and corner lounge windows built into existing structures? What part of the human brain thinks, "man this is a great open vista of Mars, just like I'd see from a dome, but somehow the window is just not expensive enough!"  ???

To be even blunter: the flimsy people won't go to Mars. Simple as that. Just like immigrating to America, or moving West in a covered wagon. You need to calibrate everything for the most hardy 10-15% of humanity, not the most delicate. Caveat: as always, the richer someone is, the nicer surroundings they can afford, and the flimsier the actual person can be. ;D

Naturally things will slowly get nicer on Mars over the decades, but it will never become as easy/cheap as life on Earth. Leaching off of Earth's "free" biosphere (as long as that lasts :-\) is just too big a planetary competitive advantage.
And of course people may be tough when they set out and get tired out and flimsy with time, as we do all.
Flimsy is very difficult to define, really  :-)
I expect most people going to Mars will be well off, or at least have rich patrons.  The wild west analogies are not correct in general, IMHO, although it will be a frontier, it is such a ridiculously difficult one that it has to be techo supported to work at all.
I tend to see Mars as a really rich suburb, rather than a frontier town.  Rather like the movie Elysium, really.
My own take on domes is that they will be aesthetic and cultural elements, but not a primary habitat element.
Glass and steel are cheap, in a relative sense, but concrete with bright lights is even cheaper.


True. The wild west was also an economic development of hospitable land taken from other humans. The Moon would be an extension of the Earth economic sphere, Mars is of no real value except as a cultural icon. Given that humans are willing to die for patches of sentimental dirt, I have a feeling that once a Mars colony becomes wildly expensive but possible, people will start a sort of space race to stamp their presence there. I expect Mos Eisleys, mosques, pyramids, pagodas and all sort of cultural landmarks to be built up once the initial colony starts to fluorish. /off_topic_fluff

From my limited experience of Antarctic folks, it'll be smart, motivated people who somehow find a way to be there, either by joining an expedition through sponsorship or somehow paying their own way. They spend half the year working and saving up, or working odd jobs to keep themselves financially stable until they can go down in the summer and earn money. Plus some people who just see it as a job.

The rich people will probably be tourists, so unfortunately I think there will be some kind of class divide right from the get go. All very speculative of course, and I'm sure we'll be surprised. Very few people would have expected something like DearMoon. It still sounds like some kind of silly sci-fi story, but here we are with the trusty Of Course I still Love You catching first stages at sea and Heart of Gold taking shape like the Enterprise being welded together in an Iowa corn field.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/03/2019 12:52 am
Finally got a grow room done.  600W per m2 or thereabouts.
If you get depressed, go and take care of the plants!


Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/03/2019 02:40 am

And of course people may be tough when they set out and get tired out and flimsy with time, as we do all.
Flimsy is very difficult to define, really  :-)

The idea of the iron-willed settler is a myth. Astronauts have mental health issues too, and they are probably the hardiest among us. Humans have psychological needs, simple as that. Furthermore, children are likely to be born a few decades in either by design or accident, and they will have psychological needs too.

These contradict nothing I wrote. ;) In fact, I agree on all points!

I do not assume some sort of infinitely hardy astronaut, just point out that some people are more hardy than others (this seems undeniable). Going to Mars will act as a "filter" to differentially (but not perfectly!) select for more hardy people (this too seems undeniable), just as Westward expansion did in a previous era (this one's debatable since I wasn't there, and I suspect few NSF posters were).

The kids worry me least of all. They'll thrive in conditions considered unimaginable by their old fashioned, sky-hugging, conservative Earthling parents. :D


I do not live in a First World Country

Ack, and I feared I would be misinterpreted like this too. Naturally first world people spend more time indoors etc, but that's not what I meant.

and some green,* open space is as much a necessity here as it is there. There are plenty of studies supporting this.

Again can of worms. My main point is that dedicated domes are just about the most expensive way to satisfy that need.

Surely we can be more imaginative/clever than "just put a bubble around some forest and glue it to the hab," you know? Integrating both plants and scenic Mars vistas with the living/working space itself (rather than a separate dome off somewhere) offers a lot of synergistic architectural and functional opportunities imo.

When the going get rough, the "plant time" will be the first to go, when in reality it's most necessary for mental health during those crisis situations. The psychological benefits should take place organically over the course of a normal day, not require special time (or dedicated habitable volume!) that will inevitably be at constant risk of re-allocation for other purposes. The cheaper we can provide colonists their "nature quota" (eg by reusing otherwise underutilized spaces in the existing habitat) the less this re-allocation risk.

Bay windows are not the same as being in a separate, relatively open space.

"Relatively open" is pretty vague, and "separate" seems hand-wavey.

Of course they're not the same, that's obvious. But why have you (seemingly arbitrarily) drawn the line in the sand that domes are "good enough," while large windows and indoor gardens are not? Where are the studies supporting this distinction?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/03/2019 04:06 am
For an "amazing" alternative that's still cheaper than domes: large shielded south-facing glazing with ajoining indoor garden areas, integrated with the living space. These could be artificially lit too, either entirely or supplementally. Various mirror arrangements could optionally be used.

(https://i.imgur.com/59WuleQ.jpg)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/03/2019 02:11 pm
So you suggest what looks like a 3m high by 4m wide area of windows for 12m2 per kitchen. The windows for 10 such kitchens would make an enclosed dome 8m in diameter. This is also quite a switch-up from your previous position:

This discussion perfectly illustrates why I think huge windows will be extravagant conspicuously consumed luxury items for the rich. Much more trouble than they're worth. Cover the building with regolith and be done with it.

From a strictly dollars-to-donuts perspective, you get to live/work on frikkin' Mars. If you don't fancy the interior decoration scheme, there's a line of less-picky bodies out the door eager to take your slot.

The ultra-rich will demand huge windows (and pay handsomely for the privilege), but no one else will be in a position to afford them (heck, this is true even on Earth where huge windows are much cheaper). That's why I expect large windows will be either communally-funded or patron-funded.

Mundane acrylic costs up to $5000/tonne. Aerospace grade carbon composite is $21 500/tonne. Let's take the the higher cost as a guide. An 8m diameter acrylic hemispherical dome 10cm thick weighs 12 tonnes and costs $215 000. Polycarbonate is about the same. Note that this is twice the thickness of the two ISS cupola pressure panes. Delivered to Mars at Musk's $200/kg figure, that's $2.4 million. Throw in an aluminium base, thermal covers etc and make it 18 tonnes.

Realistically, the vast majority of the cost will be R&D for the dome (as with any pressurised module) and shipping. 8m is not much; the 85m diameter dome in Musk's presentations would probably come much, much later. But, an 8m one can be formed and transported in a single piece and plopped down on the surface to connect to the base.

As for why I say a dome is necessary (or some other open viewing plan eg cylinder), a room will never be perceived as completely open. Boundaries, barriers and so on reduce the feeling of openness and decrease feelings of safety and calmness. In a previous study they quoted, increasing street widths were seen as less threatening. So @lamontagne you are on the right trick with wider tunnels.

https://www.researchgate.net/profile/Arthur_Stamps/publication/258132464_Effects_of_Multiple_Boundaries_on_Perceived_Spaciousness_and_Enclosure/links/56bd484e08ae9ca20a4d6bc3.pdf

Lots of useful information on windows; optimal size is about 35% of wall height and most people prefer views out onto "nature," with more complexity preferred - this being trees, vegetation, water, rocks etc.

Furthermore, some of the colony windows will be able to look into the dome, providing a green view. The new Antarctic stations feature much larger windows than before (they started off with none because planners thought they didn't need them). Halley VI has a humongous window, which the crews love.

Note that the Mars-500 crew "survived" but didn't do so swimmingly: one person became depressed, another chronicly sleep deprived and another somehow switched to a 25-hour circadian cycle. Artificial light and confined spaces were no doubt the cause of most of this. Blue-enriched light seems to help some individuals.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3574912/

https://www.researchgate.net/publication/264310151_Chronic_Artificial_Blue-Enriched_White_Light_Is_an_Effective_Countermeasure_to_Delayed_Circadian_Phase_and_Neurobehavioral_Decrements
Title: Re: Envisioning Amazing Martian Habitats
Post by: ekanellas on 05/03/2019 02:39 pm
3d printed house .contest at nasa now with 3 teams.. Spray 2 3 layers of line-x inside .result.indestructable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/03/2019 03:07 pm
A useful resource on underground lighting.

https://s3.amazonaws.com/academia.edu.documents/35108349/Natural_lighting_and_psychological_barriers_in_underground_space.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1556874171&Signature=gzUm0nM%2F2E50BeoYbbKm0C0fp5s%3D&response-content-disposition=inline%3B%20filename%3DNatural_Lighting_and_Psychological_Barri.pdf

All you ever wanted to know about windows, lighting and mental health. Interestingly, Dutch health codes say that nobody should be more than 6m away from a window for any extended period of time.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.3.5273&rep=rep1&type=pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/03/2019 05:22 pm
So you suggest what looks like a 3m high by 4m wide area of windows for 12m2 per kitchen. The windows for 10 such kitchens would make an enclosed dome 8m in diameter. This is also quite a switch-up from your previous position:

This discussion perfectly illustrates why I think huge windows will be extravagant conspicuously consumed luxury items for the rich. Much more trouble than they're worth. Cover the building with regolith and be done with it.

From a strictly dollars-to-donuts perspective, you get to live/work on frikkin' Mars. If you don't fancy the interior decoration scheme, there's a line of less-picky bodies out the door eager to take your slot.

The ultra-rich will demand huge windows (and pay handsomely for the privilege), but no one else will be in a position to afford them (heck, this is true even on Earth where huge windows are much cheaper). That's why I expect large windows will be either communally-funded or patron-funded.

Sigh.

This perfectly illustrates the danger of using inspirational example photographs. People start assuming that everything must by implemented exactly as the photo depicts, even the parts that obviously wouldn't make any sense.

If this were for a private kitchen it may be a rich person (which actually doesn't conflict with the words you quoted, so no "switch-up" here :P). More cost-optimized implementations would arrange these to be communal spaces, as I have stated many times.

Mundane acrylic costs up to $5000/tonne. Aerospace grade carbon composite is $21 500/tonne. Let's take the the higher cost as a guide. An 8m diameter acrylic hemispherical dome 10cm thick weighs 12 tonnes and costs $215 000. Polycarbonate is about the same. Note that this is twice the thickness of the two ISS cupola pressure panes. Delivered to Mars at Musk's $200/kg figure, that's $2.4 million. Throw in an aluminium base, thermal covers etc and make it 18 tonnes.

Doesn't this just show my point? Glazing is expensive. Using a big dome only makes it even more expensive.

Realistically, the vast majority of the cost will be R&D for the dome (as with any pressurised module) and shipping. 8m is not much; the 85m diameter dome in Musk's presentations would probably come much, much later. But, an 8m one can be formed and transported in a single piece and plopped down on the surface to connect to the base.

An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.

As for why I say a dome is necessary (or some other open viewing plan eg cylinder), a room will never be perceived as completely open. Boundaries, barriers and so on reduce the feeling of openness and decrease feelings of safety and calmness. In a previous study they quoted, increasing street widths were seen as less threatening. So @lamontagne you are on the right trick with wider tunnels.


https://www.researchgate.net/profile/Arthur_Stamps/publication/258132464_Effects_of_Multiple_Boundaries_on_Perceived_Spaciousness_and_Enclosure/links/56bd484e08ae9ca20a4d6bc3.pdf

So TL;DR Permeability Theory, therefore big expensive domes. Or should I say Permeability Hypothesis?

Showing a few dozen CGI renderings on a powerpoints to grad students and asking them to rate on 6 axes (one of which is "safety") and then doing correlations is fun, but it falls far short of justifying multi-million dollar expenditures on frivolous (yes I said it) domes.

Lots of useful information on windows; optimal size is about 35% of wall height and most people prefer views out onto "nature," with more complexity preferred - this being trees, vegetation, water, rocks etc.

But was this determined by comparing outdoor nature to indoor nature, or by comparing outdoor nature to outdoor barrenness?

I think the whole idea is just people getting hung up on the outdoor vs. indoor distinction. There is no need to construct a "fake outdoors" to enclose all our natural elements.

Furthermore, some of the colony windows will be able to look into the dome, providing a green view. The new Antarctic stations feature much larger windows than before (they started off with none because planners thought they didn't need them). Halley VI has a humongous window, which the crews love.

"A (singular) humongous window" proves my point. They didn't use a dome.

Note that the Mars-500 crew "survived" but didn't do so swimmingly: one person became depressed, another chronicly sleep deprived and another somehow switched to a 25-hour circadian cycle. Artificial light and confined spaces were no doubt the cause of most of this. Blue-enriched light seems to help some individuals.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3574912/

https://www.researchgate.net/publication/264310151_Chronic_Artificial_Blue-Enriched_White_Light_Is_an_Effective_Countermeasure_to_Delayed_Circadian_Phase_and_Neurobehavioral_Decrements

Yes, for good circadian rhythm you need lighting that works similar to the f.lux software package. These LED lights have already begun testing on the ISS, replacing the previous single-temperature fluorescent lights (this also retires mercury release risk).

http://web.archive.org/web/20161106152857/https://www.nasa.gov/mission_pages/station/research/experiments/2279.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/03/2019 05:29 pm
An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.
You arnt talking about the Chomper, are you? Revealed in an official SpaceX presentation in 2017, and recently revisited by NASA Goddard Space Center after consulting with SpaceX? I wouldn't classify Chomper as as "off the wall speculation", though I am skeptical how useful it would be planetside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/03/2019 05:51 pm
An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.
You arnt talking about the Chomper, are you? Revealed in an official SpaceX presentation in 2017, and recently revisited by NASA Goddard Space Center after consulting with SpaceX? I wouldn't classify Chomper as as "off the wall speculation", though I am skeptical how useful it would be planetside.

The very same. There's zero evidence from SpaceX or Goddard that Chomper is anything more than a microgravity satellite deployment door. Using Chomper on Mars for large diameter cargo is off-the-wall speculation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 05/03/2019 06:10 pm
An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.
You arnt talking about the Chomper, are you? Revealed in an official SpaceX presentation in 2017, and recently revisited by NASA Goddard Space Center after consulting with SpaceX? I wouldn't classify Chomper as as "off the wall speculation", though I am skeptical how useful it would be planetside.

The very same. There's zero evidence from SpaceX or Goddard that Chomper is anything more than a microgravity satellite deployment door. Using Chomper on Mars is off-the-wall speculation.

This whole thread is speculation. If there is a need for large payloads then SpaceX will make a chomper-type SS for Mars. Something with a better payload bay door design for use on Mars. Large modules make more sense than building everything Ikea style.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/03/2019 06:24 pm
An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.
You arnt talking about the Chomper, are you? Revealed in an official SpaceX presentation in 2017, and recently revisited by NASA Goddard Space Center after consulting with SpaceX? I wouldn't classify Chomper as as "off the wall speculation", though I am skeptical how useful it would be planetside.

The very same. There's zero evidence from SpaceX or Goddard that Chomper is anything more than a microgravity satellite deployment door. Using Chomper on Mars is off-the-wall speculation.

This whole thread is speculation. If there is a need for large payloads then SpaceX will make a chomper-type SS for Mars. Something with a better payload bay door design for use on Mars. Large modules make more sense than building everything Ikea style.
As a general rule, I don't agree. Ikea style, as long as you have people on hand who can read the instructions in the box, is pretty damn efficient.

However, I will agree that there are SOME payloads that simply arnt practical to assemble on mars. Nuclear reactors, for instance, or large unitary industrial devices. (smelters, ect) For that, the Chomper will eventually be needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/03/2019 06:59 pm
An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.
You arnt talking about the Chomper, are you? Revealed in an official SpaceX presentation in 2017, and recently revisited by NASA Goddard Space Center after consulting with SpaceX? I wouldn't classify Chomper as as "off the wall speculation", though I am skeptical how useful it would be planetside.

The very same. There's zero evidence from SpaceX or Goddard that Chomper is anything more than a microgravity satellite deployment door. Using Chomper on Mars is off-the-wall speculation.

This whole thread is speculation. If there is a need for large payloads then SpaceX will make a chomper-type SS for Mars. Something with a better payload bay door design for use on Mars. Large modules make more sense than building everything Ikea style.


By "better payload bay door design," I presume you have already made up your mind. But I dispute the 'better' claim: is a Super-Guppy large diameter payload plane 'better' than a conventional cargo aircraft? Why do conventional cargo aircraft dominant the airfreight market, while Super Guppy et al are relegated to niche transport jobs?

Certainly we can all see differences between airfreight and Starship (flight rate etc), but I can't see how any of those would flip the economics around.

"IKEA style" is rather belittling of prefabricated modular composite construction, which is the basis of most large commercial buildings on Earth. Plus larger building sizes than even Starship++ diameter are desirable to economize the radiation shield, so prefab construction is imo the way to go.

Prefab module assembly can be automated, or mostly so. Do not imagine this as just like regular construction except general-purpose constructor bots replacing humans (this is as absurd as imagining that a dishwasher must be implemented like Rosie from the Jetsons). Rather the structural parts themselves can be designed to unfold into place.

I rather like the idea of an inflatable tensile cellular "scaffold." Just unfold it, stake it down, inflate it with breathable air, send in the crew to bolt the (already in place) columns and beams and so on together, cover in shielding dirt/water, and move in. This economical assembly sequence can be employed for Earth-imported, ISRU, or hybrid hab designs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 05/03/2019 07:21 pm
By "better payload bay door design," I presume you have already made up your mind. But I dispute the 'better' claim: is a Super-Guppy large diameter payload plane 'better' than a conventional cargo aircraft? Why do conventional cargo aircraft dominant the airfreight market, while Super Guppy et al are relegated to niche transport jobs?

By better I mean don't hinge the chomper hatch aft (bottom when landed). It gets in the way.

Super-Guppy is the wrong comparison. That assumes a larger than normal fuselage diameter. Better comparison would be passenger aircraft versus cargo aircraft. Small passenger and luggage hatches versus large cargo hatch.

As a general rule, I don't agree. Ikea style, as long as you have people on hand who can read the instructions in the box, is pretty damn efficient.

However, I will agree that there are SOME payloads that simply arnt practical to assemble on mars. Nuclear reactors, for instance, or large unitary industrial devices. (smelters, ect) For that, the Chomper will eventually be needed.

There will be big industrial payloads at some point and a large cargo SS will be needed. Then large habitat segments can be shipped too if ISRU isn't building them locally yet.

You guys are right about prefab. With the right techniques, assembly can be simplified for habitats from Earth or built locally.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/03/2019 08:41 pm
An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.
You arnt talking about the Chomper, are you? Revealed in an official SpaceX presentation in 2017, and recently revisited by NASA Goddard Space Center after consulting with SpaceX? I wouldn't classify Chomper as as "off the wall speculation", though I am skeptical how useful it would be planetside.

The very same. There's zero evidence from SpaceX or Goddard that Chomper is anything more than a microgravity satellite deployment door. Using Chomper on Mars for large diameter cargo is off-the-wall speculation.

How else were you thinking of carrying your giant waffle hab?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/04/2019 12:50 am
An 8 meter done won't fit through the door (and no, I don't buy the off-the-wall speculation about a huge door on Starship, and I certainly wouldn't assume it is available at any point).

Oversized transport is more expensive, not less. See Super Guppy planes etc.
You arnt talking about the Chomper, are you? Revealed in an official SpaceX presentation in 2017, and recently revisited by NASA Goddard Space Center after consulting with SpaceX? I wouldn't classify Chomper as as "off the wall speculation", though I am skeptical how useful it would be planetside.

The very same. There's zero evidence from SpaceX or Goddard that Chomper is anything more than a microgravity satellite deployment door. Using Chomper on Mars for large diameter cargo is off-the-wall speculation.

How else were you thinking of carrying your giant waffle hab?

Er, in pieces of course! Inflatable/flexible components would be folded up and packaged.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/04/2019 01:32 am
By better I mean don't hinge the chomper hatch aft (bottom when landed). It gets in the way.

Just to wade into the speculation: the lightweight, microgravity (and yes, to both) hinge would be just about the first thing disconnected to prevent ground handling damage, most simply by removing the hinge pin.

Still there's zero evidence from SpaceX that Chomper will land on Mars, despite them surely having worked the problem.

Super-Guppy is the wrong comparison. That assumes a larger than normal fuselage diameter. Better comparison would be passenger aircraft versus cargo aircraft. Small passenger and luggage hatches versus large cargo hatch.

Starship already has large cargo hatchs.

There will be big industrial payloads at some point and a large cargo SS will be needed.

"Will be needed" begs the question. But why stop there? I can equivalently claim that even larger industrial payloads will be needed, bigger even than StarshipMax (ie the largest possible successor to Starship). What then?

Akin's Law #38: "Capabilities drive requirements, regardless of what the systems engineering textbooks say."
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 05/04/2019 01:57 am
By better I mean don't hinge the chomper hatch aft (bottom when landed). It gets in the way.

Just to wade into the speculation: the lightweight, microgravity (and yes, to both) hinge would be just about the first thing disconnected to prevent ground handling damage, most simply by removing the hinge pin.

Still there's zero evidence from SpaceX that Chomper will land on Mars, despite them surely having worked the problem.

Super-Guppy is the wrong comparison. That assumes a larger than normal fuselage diameter. Better comparison would be passenger aircraft versus cargo aircraft. Small passenger and luggage hatches versus large cargo hatch.

Starship already has large cargo hatchs.

There will be big industrial payloads at some point and a large cargo SS will be needed.

"Will be needed" begs the question. But why stop there? I can equivalently claim that even larger industrial payloads will be needed, bigger even than StarshipMax (ie the largest possible successor to Starship). What then?

Akin's Law #38: "Capabilities drive requirements, regardless of what the systems engineering textbooks say."

"Simply by removing the hinge pin" is not a serious suggestion. You also stick to believing only one version of SS will be the only vehicle used. I'm having a hard time taking any of your comments seriously.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/04/2019 03:46 am
By better I mean don't hinge the chomper hatch aft (bottom when landed). It gets in the way.

Just to wade into the speculation: the lightweight, microgravity (and yes, to both) hinge would be just about the first thing disconnected to prevent ground handling damage, most simply by removing the hinge pin.

Still there's zero evidence from SpaceX that Chomper will land on Mars, despite them surely having worked the problem.

Super-Guppy is the wrong comparison. That assumes a larger than normal fuselage diameter. Better comparison would be passenger aircraft versus cargo aircraft. Small passenger and luggage hatches versus large cargo hatch.

Starship already has large cargo hatchs.

There will be big industrial payloads at some point and a large cargo SS will be needed.

"Will be needed" begs the question. But why stop there? I can equivalently claim that even larger industrial payloads will be needed, bigger even than StarshipMax (ie the largest possible successor to Starship). What then?

Akin's Law #38: "Capabilities drive requirements, regardless of what the systems engineering textbooks say."

"Simply by removing the hinge pin" is not a serious suggestion.

Fortunately that's not what I wrote!

I said "most simply by removing the hinge pin," ie you can certainly design a more complex mechanism than that, but why bother? A simple retracting hinge pin works well enough, and avoids unnecessary mechanical complexity.

You also stick to believing only one version of SS will be the only vehicle used.

I did not say that and I do not believe that.

I'm having a hard time taking any of your comments seriously.

What can I do though? Both problems ultimately stemmed from misreading my post.  :-\

Edit: snark
Title: Re: Envisioning Amazing Martian Habitats
Post by: Thrustpuzzle on 05/05/2019 12:16 am
How tall do living space ceilings need to be? This isn't a mere stylistic point like it is with an Earth condo. Taller ceilings require more effort, digging, and support, and are weaker structurally. But, as a Mars base, it will likely be under continual construction and change.  it's likely you'll need to move equipment and materials through (even the living volume) and it would suck if you can't physically move, say, some long piping or a water tank part through your living volume to install in a new area on the other side.  Doorways likely need to be designed with this same issue in mind.

Tall ceilings also may be more necessary than expected due to the 0.38g surface gravity. Would it be easy to take a big stride and bang your head on even a 2 meter ceiling? Certainly you could deliberately jump and touch even a super tall 3 meter ceiling like you might find in an Earth based industrial workshop.

Tall ceilings tend to hamper heating and ventilation performance on Earth, but maybe this is less of an issue on Mars where the lower gravity causes correspondingly less buoyant air force and therefore less convection?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 05/05/2019 12:54 am
Can we dial the snark back a little, please. Some of the long time posters and newcomers are getting a bit testy with each other. Don't. Be excellent to each other. Thank you.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/05/2019 02:40 am
Does industrial design count in Amazing habitats?


A 50 m3/s (100 000 cfm) atmospheric treatment plant for Mars propellant and atmospheric production.

More or less to scale, but a lot of guesses.  This would treat 1 kg/s af atmosphere, so 3600 x 24 x 365 x 0,9 downtime = 28 million kg, or 28 000 tonnes.  This is enough carbon for over 40 Starships worth of propellant.  Not quite enough Oxygen but then there will be plenty of oxygen from water electrolysis.

It would be built and tested on Earth, and shipped to Mars in sub-assemblies.

There would also be a 1:10 scale version coming with the first Ship to Mars.
The dust collector is not very heavy, mostly light metal plate and cloth.  The compressor would be fairly massive, but definitively much less than 100 tonnes.  The electric motor would be about 800 horsepower, so a few tonnes itself.

Then the coolers have a lot of heat exchanging surface so they mass quite a bit, while the separation tanks are fairly light, but the various media would be pretty heavy. all in all.
They all work in the one alternating one absorbing regenerating cycle using in similar productions plants on Earth.  These are pretty durable.  Not all the pipes are there, no cooling pipes, in particular.  The actuel propellant and gas holding tanks are not illustrated either.

Fairly small, I think in view of the capacity.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/05/2019 02:47 am
How tall do living space ceilings need to be? This isn't a mere stylistic point like it is with an Earth condo. Taller ceilings require more effort, digging, and support, and are weaker structurally. But, as a Mars base, it will likely be under continual construction and change.  it's likely you'll need to move equipment and materials through (even the living volume) and it would suck if you can't physically move, say, some long piping or a water tank part through your living volume to install in a new area on the other side.  Doorways likely need to be designed with this same issue in mind.

Tall ceilings also may be more necessary than expected due to the 0.38g surface gravity. Would it be easy to take a big stride and bang your head on even a 2 meter ceiling? Certainly you could deliberately jump and touch even a super tall 3 meter ceiling like you might find in an Earth based industrial workshop.

Tall ceilings tend to hamper heating and ventilation performance on Earth, but maybe this is less of an issue on Mars where the lower gravity causes correspondingly less buoyant air force and therefore less convection?
Rooms might have North American height ceilings, but I would expect corridor to have higher ceilings, to create a feeling of openness.  There may be a fair amount of ventilation required, in particular during the day when 'daylight' lighting is active.  I would expect it to be quite a bit more powerful than typical lighting levels in Earth buildings, because they need to give the impression of a difference between interior and exterior.  And the cooling deltaT is not very high, and air is a terrible thermal conductor, so we need to move a fair amount.
Wouldn't convection go faster on Mars?  It's energy driven, after all, and buoyancy is a factor of density, not of gravity ( I think :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/05/2019 05:51 am

The dust collector is not very heavy, mostly light metal plate and cloth.

Love the design (all of it, not just the quote)!

Looks like a standard industrial baghouse filter? I confess I did check these out a while back, specifically with this purpose in mind. :D

https://en.wikipedia.org/wiki/Baghouse#Types

Based on that comparison table, pulse-jet cleaning seems clearly the way to go. Highest air-to-cloth ratio and gentlest cleaning cycle (which maximizes expensive consumable bag life). It also permits continuous operation without multiple baghouse compartments, so there are no moving parts required to switch flow between compartments.

(https://upload.wikimedia.org/wikipedia/commons/b/b9/Reverse-Jet.svg)

If a pulse-jet baghouse is used (vs shaker or reverse-air designs), and since the "dirty" side always operates at ambient outdoor pressure (since it is the outdoors), then even the lower housing and dust hopper might be eliminated, right? They're not too heavy, but if unneeded then deleting them is even lighter. :)

On Earth baghouses must contain the process dust (often baddies like asphalt etc), but on Mars it only needs to exclude outdoor dust from the output gas. If anything a simple hanging curtain might shade the bags from UV and minimize suspended dust ingestion from the surface boundary layer (I was puzzled to see the air inlet located at the bottom of the dust collector, for this reason). This might also simplify bag maintenance — no need to climb up inside the baghouse, just walk up to it at ground level (or a man lift, or a catwalk, but preferably at ground level) and change/service the bags.

A hopper may still be desirable for ease-of-emptying, but how much dust buildup will there be really? The Mars atmosphere is incredibly thin. If needed, possibly the curtain might be gathered at the base, resulting in a pile/line of dust accumulation.

Personally I expect nothing elaborate will be needed, just let the dust settle on the ground. If it gets too thick (and this should take a long time), quickly blast it aside with the dusting wand during regular maintenance. Or if one prefers, use a shovel.

"Simplify, then add lightness."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Thrustpuzzle on 05/05/2019 07:25 am
The dust collector is not very heavy, mostly light metal plate and cloth.
Filtering the fine dust of Mars would be a pain even with very small pore sizes. Electrostatic works better but is also a pain to clean.

As an armchair design idea, there may be a strong synergy between the ISRU's need for both clean CO2  and pure H2O.    Your inputs are ultra dry micro-scale-dust-y CO2, and solids of very dirty ice mixed with a large fraction of regolith and rock.  So one rough idea is to coarsely crush the dirty ice while heating while in a dusty CO2 atmosphere. Water will evaporate, and the ultra-small and ultra-dry dust in gas suspension will likely be hydrophilic and PRECIPITATE water vapor, increasing its weight and therefore settling faster. At the very least it forms condensation nuclei. Use a gas vortex to extract air (gaseous CO2 and H2O vapor) at the top (the spinning force will cause solids like damp and now heavier dust to condense on chilled walls). The exported gas is a mixture of H2O vapor and CO2, but no dust and no regolith.  Compress and chill this flow to separate the two by fractional condensation.  Output is pure CO2 and pure H2O, and mixed damp regolith (also holding the now muddy dust)
Advantage is no filters to clean and maintain.

Perhaps this belongs in the ISRU thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/05/2019 08:19 am
How tall do living space ceilings need to be? This isn't a mere stylistic point like it is with an Earth condo. Taller ceilings require more effort, digging, and support, and are weaker structurally. But, as a Mars base, it will likely be under continual construction and change.  it's likely you'll need to move equipment and materials through (even the living volume) and it would suck if you can't physically move, say, some long piping or a water tank part through your living volume to install in a new area on the other side.  Doorways likely need to be designed with this same issue in mind.

Excellent point.

On ISS the International Standard Payload Racks are designed specifically to fit through the Common Berthing Mechanism hatch. Fun fact, ISPR racks are also designed to swing away from the module wall, allowing hull breaches to be repaired from the inside as well (along with more mundane tasks like rack replacement or accessing cable and plumbing runs).

That small square CBM hatch may work well enough in microgravity, but on Mars a door-shaped hatch (preferably standardized) is needed.


Tall ceilings also may be more necessary than expected due to the 0.38g surface gravity. Would it be easy to take a big stride and bang your head on even a 2 meter ceiling? Certainly you could deliberately jump and touch even a super tall 3 meter ceiling like you might find in an Earth based industrial workshop.

Clearly you mean "3 meter" and "4 meter" here, but I find myself seized by the volume-saving potential of sending Hobbit colonists....   ;D

But seriously, here's a test of walking/running under Mars gravity:

https://www.youtube.com/watch?v=LvnDIDqcfGI

Counterintuitively the gait doesn't really get higher, so much as longer. Actual vertical leaps aren't all that common in daily life (except working out/sports), and you can't exactly do one by accident. I mean... try it. :)​

Bouncing during running (technically called "vertical oscillation") is surprisingly small at 2-5 inches (6-13 cm), only a fraction of vertical leap heights which tends to average 16-20 inches (40-50 cm) in men. These are all terrestrial numbers, so multiply by 2.63 for Mars gravity.

Using VO, that means maybe an extra 8 inches (20 cm) of ceiling height? More than that shouldn't really be necessary to prevent accidentally bumping the ceiling (bc again, you can't accidentally vertical leap).

Tall ceilings tend to hamper heating and ventilation performance on Earth, but maybe this is less of an issue on Mars where the lower gravity causes correspondingly less buoyant air force and therefore less convection?

Yes. Less convection, and also less temperature stratification (both driven by buoyancy).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/05/2019 08:56 am
Found this interesting proposal for a lunar pop tent, applicable to Mars as well A membrane keeps the dust out of the sleeping area once the astronauts doff their suits. Since it's a low pressure environment (suit pure oxygen at 1/3 bar), it would also be quite light, possibly partly transparent as well.

(https://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2015/1-habitatisdes.jpg)

https://phys.org/news/2015-06-habitat-moon.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 05/05/2019 12:02 pm
Found this interesting proposal for a lunar pop tent, applicable to Mars as well A membrane keeps the dust out of the sleeping area once the astronauts doff their suits. Since it's a low pressure environment (suit pure oxygen at 1/3 bar), it would also be quite light, possibly partly transparent as well.
..
snip images see post above
...
https://phys.org/news/2015-06-habitat-moon.html
The pressure differential across the membrane would need to be low... even 1/15th atmos is 1 lb/sqin or 144lb/sqft !
However I think you were talking about pressure in relation to the mass of the tent, due to its reduced strength requirement.  Are there products on earth that store pressurised gas in "balloons" at +1/3 bar? Are they made of Kevlar and rubber? A quick search on inflatable boats (RIBS) gives tube pressure as 3 PSI , and rigid floor pressure as 5 PSI. The tubes are made of very tough material, and even a small boat is heavy when folded up. OK impact and abrasion resistance etc account for some of that, but such(some, maybe less) toughness will also be needed on mars for your suggested use.

Edit: I'm not denying your idea, just pointing out it may not be as easy as it appears.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/05/2019 02:52 pm
Found this interesting proposal for a lunar pop tent, applicable to Mars as well A membrane keeps the dust out of the sleeping area once the astronauts doff their suits. Since it's a low pressure environment (suit pure oxygen at 1/3 bar), it would also be quite light, possibly partly transparent as well.
..
snip images see post above
...
https://phys.org/news/2015-06-habitat-moon.html
The pressure differential across the membrane would need to be low... even 1/15th atmos is 1 lb/sqin or 144lb/sqft !
However I think you were talking about pressure in relation to the mass of the tent, due to its reduced strength requirement.  Are there products on earth that store pressurised gas in "balloons" at +1/3 bar? Are they made of Kevlar and rubber? A quick search on inflatable boats (RIBS) gives tube pressure as 3 PSI , and rigid floor pressure as 5 PSI. The tubes are made of very tough material, and even a small boat is heavy when folded up. OK impact and abrasion resistance etc account for some of that, but such(some, maybe less) toughness will also be needed on mars for your suggested use.

Edit: I'm not denying your idea, just pointing out it may not be as easy as it appears.

It's not my idea (other than applying it to Mars), just pointing out an article of interest. Inflating the membrane is easy, it's basically a large beach ball.

As for materials... I'm not sure what you're trying to say? Are you asking if storing pressurised gas at 1bar+ in rubber balloons is feasible? Because it most assuredly is.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/05/2019 03:49 pm

The dust collector is not very heavy, mostly light metal plate and cloth.

Love the design (all of it, not just the quote)!

Looks like a standard industrial baghouse filter? I confess I did check these out a while back, specifically with this purpose in mind. :D


Based on that comparison table, pulse-jet cleaning seems clearly the way to go. Highest air-to-cloth ratio and gentlest cleaning cycle (which maximizes expensive consumable bag life). It also permits continuous operation without multiple baghouse compartments, so there are no moving parts required to switch flow between compartments.


If a pulse-jet baghouse is used (vs shaker or reverse-air designs), and since the "dirty" side always operates at ambient outdoor pressure (since it is the outdoors), then even the lower housing and dust hopper might be eliminated, right? They're not too heavy, but if unneeded then deleting them is even lighter. :)

On Earth baghouses must contain the process dust (often baddies like asphalt etc), but on Mars it only needs to exclude outdoor dust from the output gas. If anything a simple hanging curtain might shade the bags from UV and minimize suspended dust ingestion from the surface boundary layer (I was puzzled to see the air inlet located at the bottom of the dust collector, for this reason). This might also simplify bag maintenance — no need to climb up inside the baghouse, just walk up to it at ground level (or a man lift, or a catwalk, but preferably at ground level) and change/service the bags.

A hopper may still be desirable for ease-of-emptying, but how much dust buildup will there be really? The Mars atmosphere is incredibly thin. If needed, possibly the curtain might be gathered at the base, resulting in a pile/line of dust accumulation.

Personally I expect nothing elaborate will be needed, just let the dust settle on the ground. If it gets too thick (and this should take a long time), quickly blast it aside with the dusting wand during regular maintenance. Or if one prefers, use a shovel.

"Simplify, then add lightness."
Using a Martian dust concentration of 2e-7kg/m3  (this may be wrong)
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.693.1428&rep=rep1&type=pdf
Then we get 315 kg of dust per year.  So that is not all that much dust!

However, I don't think we can open the bottom of the baghouse because a normal baghouse is probably impossible on Mars due to the low pressure.  A typical baghouse has a pressure drop of 4-10 inches of water through the cloth, so 1000 Pa to 2500 Pa.  600 Pa (martian pressure) is not enough to drive the atmosphere through the cloth and the dust cake.  So we will need to have fans on the air side, that will push the air through the filter fabric.
Fortunately the dust should not really wear down the fan blades much.
We will not need to activate cleaning systems much, because there is so little dust  (again, if my atmospheric dust loading number is correct).

So this will be a pressurized bag house, but not at a very high pressure one, and it can stay rectangular.
Using 4mm plate, we might have a mass of 31 kg/m2.  80 m2 per face x 4 faces x 71 x 2 (fudge factor) = 44 000 kg, so 44 tonnes. Seems doable.
We could switch to cylindrical bag houses with thinner walls, would make sense




Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/05/2019 05:19 pm
Virtually all Martian dust particles in the atmosphere are magnetic, if that helps.

I wonder what the dust mass flow is in a dust storm. Might make an interesting new kind of wind turbine. Or screw up a conventional one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/05/2019 06:55 pm
Found this interesting proposal for a lunar pop tent, applicable to Mars as well A membrane keeps the dust out of the sleeping area once the astronauts doff their suits. Since it's a low pressure environment (suit pure oxygen at 1/3 bar), it would also be quite light, possibly partly transparent as well.

(https://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2015/1-habitatisdes.jpg)

https://phys.org/news/2015-06-habitat-moon.html

Nice find!

For further reading, the original paper is available here: https://www.sciencedirect.com/science/article/pii/S0094576515001125

Schreiner, S. S., Setterfield, T. P., Roberson, D. R., Putbrese, B., Kotowick, K., Vanegas, M. D., … Head, J. W. (2015). An overnight habitat for expanding lunar surface exploration. Acta Astronautica, 112, 158–170. doi:10.1016/j.actaastro.2015.03.012
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/05/2019 07:12 pm
Virtually all Martian dust particles in the atmosphere are magnetic, if that helps.

I wonder what the dust mass flow is in a dust storm. Might make an interesting new kind of wind turbine. Or screw up a conventional one.
If we had nuclear reactors perhaps, yes we might run this during a storm.  Magnetic separation of iron oxide by rare Earth magnets (and before that with regular magnets) is a real industrial process, and electrostatic precipitators work on magnetite.  The concentration of dust in storms goes up quite a bit, there a papers on the subject, but at this point I think the illustrated dust collectors are good stand ins for some kind of separation equipment.  The exact process matters not that much, but I like to think we may have a handle on the size.

To be honest I thought they would be much larger.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/05/2019 08:50 pm
CO2 and other atmospheric gases extraction facility.
1 kg/s massic, or 50 m3/s volumic.  The atmosphere is slightly pressurized with fans, filtered, compressed down to the separation pression of water, cooled, passed through absorption filters, then cooled again and pressurized down to the triple point of CO2.  CO2 is separated out, then nitrogen, the Argon.  The oxygen and whatever is left over is returned to the atmosphere.

The pipes and tanks are insulated to prevent freezing during off hours.
The round pillbox is the top of a node, connecting up the production habitat tubes.
The big brown tubes are insulated habitats, while the even larger tube at the back is a group of horizontal liquid oxygen tanks.  Don't know yet if everything would be covered with regolith, depends on radiation hazards determined on site.
This facility can produce the propellant for over 40 Starship sized vehicles over 2 years with ample capacity to spare.

The spacesuited person at the front is just happy to be there  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/05/2019 09:01 pm
Inside, under the saltshaker.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/05/2019 09:08 pm
For my next little project, I'm thinking of a little stream , that goes from one habitat area to another.  The kind of streams you find in parks, or in botanical gardens.  A kind of linear park.  What might be nice to see?  Waterfalls and bubbly ponds?  My theme for my first habitat sector is Estepona.  I would expect the next sector to be resolutely chinese.  With chinese characters and a distinct chinese identity.  But what is a chinese identity?  I would like to avoid being overly Disney on this.
BTW Disney's were the names John Varley used for this type of underground habitats in his excellent novellas and novels about the Eights Worlds.  Potent stuff, those stories.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/08/2019 03:32 am
While researching Lampyridae's lunar pop tent I came across this design for a large lunar/Mars base.

Total aluminum frame mass is 6,649 kg, supporting ~610 m² (by my measurement) of floor area on five levels. Internal pressure forces are entirely carried by the outer inflatable.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900015683.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 05/08/2019 03:42 am
While researching Lampyridae's lunar pop tent I came across this design for a large lunar/Mars base.

Total aluminum frame mass is 6,649 kg, supporting ~610 m² (by my measurement) of floor area on five levels. Internal pressure forces are entirely carried by the outer inflatable.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900015683.pdf

So one reason I am a fan of cylinders/silos instead of Sphere's is mainly because their building process can be far more automated. Does anyone know of a way to (mostly) automatically construct spherical pressure vessels like this?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 05/08/2019 04:47 am
CO2 and other atmospheric gases extraction facility.
1 kg/s massic, or 50 m3/s volumic.  The atmosphere is slightly pressurized with fans, filtered, compressed down to the separation pression of water, cooled, passed through absorption filters, then cooled again and pressurized down to the triple point of CO2.  CO2 is separated out, then nitrogen, the Argon.  The oxygen and whatever is left over is returned to the atmosphere.
Why? What exactly is left? everything has a use I would think... and if it's a trace, just saving it might not take that much tankage.... I would think you'd want to save the oxygen at least.
Quote
The spacesuited person at the front is just happy to be there  ;-)
I would be too! nice render.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/08/2019 01:14 pm
While researching Lampyridae's lunar pop tent I came across this design for a large lunar/Mars base.

Total aluminum frame mass is 6,649 kg, supporting ~610 m² (by my measurement) of floor area on five levels. Internal pressure forces are entirely carried by the outer inflatable.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900015683.pdf

So one reason I am a fan of cylinders/silos instead of Sphere's is mainly because heir building process can be far more automated. Does anyone know of a way to (mostly) automatically construct spherical pressure vessels like this?

First thing's first: which way were you picturing for the (mostly) automated construction of cylinders/silos?  ???

Sadly analyzing the spherical inflatable pressure vessel isn't within the scope of the linked paper. Only the internal framing (supporting static loads) is analyzed. This is not a cellular pressure vessel, so the internal framing carries none of the pressure restraining forces.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 05/08/2019 11:00 pm
While researching Lampyridae's lunar pop tent I came across this design for a large lunar/Mars base.

Total aluminum frame mass is 6,649 kg, supporting ~610 m² (by my measurement) of floor area on five levels. Internal pressure forces are entirely carried by the outer inflatable.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900015683.pdf

So one reason I am a fan of cylinders/silos instead of Sphere's is mainly because heir building process can be far more automated. Does anyone know of a way to (mostly) automatically construct spherical pressure vessels like this?

First thing's first: which way were you picturing for the (mostly) automated construction of cylinders/silos?  ???

Sadly analyzing the spherical inflatable pressure vessel isn't within the scope of the linked paper. Only the internal framing (supporting static loads) is analyzed. This is not a cellular pressure vessel, so the internal framing carries none of the pressure restraining forces.

See attached:
http://www.cobratanks.com/images/cobra%20tank%20brochure.pdf

Key word is 'mostly'. Still better than building the entire thing by hand. They're limited to roughly 25m high and 40m in diameter, but it could conceivably be made much larger on Mars.

Simply build two tanks inside each other (one 40m in diameter, the other 30m) and fill the gap with regolith. Boom! Radiation shielding (mostly) sorted. Problem then is how best to do it from above. Water tank on the roof maybe? Another possibility would be to build a brick wall outside of a 40m wide tank, 5m thick, which can be done again in a mostly automated fashion (https://www.fbr.com.au/). 
 
Process can work, but it's whether or not it can be made to look 'Amazing' both inside and outside AND the issue with the radiation from above, hence the question as to whether or not a Spherical pressure vessel could be built in an automated fashion.

PS: As I've said before, steel can be made on Mars very easily.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/18/2019 05:38 am
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1559548;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1559548;image)

Is there any reason you have the interconnector tubes so long and narrow? Volume/area works better if they are shorter and wider, similarly, shielding would be more mass-efficient.

It would also make more sense for them to be the same diameter as the oxygen tanks in the background, since you have to have the tooling for that anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/18/2019 05:46 am
The kids worry me least of all. They'll thrive in conditions considered unimaginable by their old fashioned, sky-hugging, conservative Earthling parents.

There are aspects of development that go beyond "hardiness" or what you grow up used to.

For example, you need sufficient brightness of light for your eyes to develop normally. You need a minimum amount of UV for your skin to develop normally. You need sufficient Vitamin D (still easiest to get through UV) for your brain to develop properly.

The good news is that artificially lit agricultural spaces will be the brightest lit parts of the hab. Brighter than the biggest bay windows. And agriculture is likely to be the safest occupation for kids on Mars. Likewise, adding enough UV to the lights is pretty easy. But they are things you need to do intentionally, not just handwave.

† Kids need exercise for their vestibular system and motor cortex to develop properly, and they need to learn how to be Martians. They will work besides their parents, it will just happen. The artificial separation between "work" and "life" will not exist on Mars for a long time. It will be, IMO, much closer to a traditional tribal lifestyle, in spite of the high-tech aspect.

When the going get rough, the "plant time" will be the first to go, when in reality it's most necessary for mental health during those crisis situations.

OTOH, it'll be all-hands-on-deck during harvest. So lots of extra exposure to light, greenery, fresh food, physical exercise, and mixed company doing work that doesn't require excessive mental concentration, allowing plenty of mental horsepower for socialisation and banter.†† Those are all good things for human psychology.

‡ Reward for extra hands is eating while you work.
†† "I know. Sounds awful, doesn't it." - Marvin.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/18/2019 05:47 am
I think @rakaydos is referring to something like this:
(http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg)
Same concept, but fixed in place, using the illusion to make meters of intervening radiation shielding "disapear" (the inside of the skylight would use a transparent shielding, like water) but not actually concentrating the light beyond martian Sol.

Any kind of focusing lens/mirrors/illusion won't work with diffuse light. (Even if you are "decompressing" the light back out at the output, you need highly directional light at the input to achieve the illusion/focus/whatever.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/18/2019 06:06 pm
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1559548;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1559548;image)

Is there any reason you have the interconnector tubes so long and narrow? Volume/area works better if they are shorter and wider, similarly, shielding would be more mass-efficient.

It would also make more sense for them to be the same diameter as the oxygen tanks in the background, since you have to have the tooling for that anyway.
They are long and narrow to save on materials. The strain on the tanks goes up with the diameter, and I want to use less strong materials, that come from Earth, in my colony scenario.  Also, I'm using the same liners as my underground tunnels, so common tooling.
I've supposed two diameters for tunnels: one about 7x10 for general use, and the other about 12m in diameter for public spaces, and in the case of the image, tanks.  the 7x10 is to increase the ground area.  Less effective volume to wall ratio, but I think a bit more practical for rooms and indoor farming.  While the circular shape is fine for tanks.  The oval shape is dug with a roadheader, that is a less equipment intensive piece of machinery than a tunneling machine.
Although they are illustrated unburied, I'm in two minds about this, work to bury vs radiation risk in indoor farming and industrial areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/19/2019 12:58 am
Is there any reason you have the interconnector tubes so long and narrow? Volume/area works better if they are shorter and wider, similarly, shielding would be more mass-efficient.
They are long and narrow to save on materials. The strain on the tanks goes up with the diameter

We were both wrong.

If you keep the same wall strength (burst pressure) and the same total mass of wall material, internal-volume & length are exactly inversely proportionally. Make the tube longer and narrower, or shorter and wider, and the mass and internal volume both remain the same. (I used a circular cylinder for simplicity, but I think the same should apply to an oval cylinder.)

So there's no particular advantage going short/wide, but there's also no advantage going long/narrow. You are better off just picking one diameter for your construction. 12m in your example. (Say four stories, perhaps split as two levels on two "road" levels with ~5m ceilings and a small volume below and above for shared utilities.)

[I was right about the shielding being better with short/wide, though. Just as the wall thickness increases as you shorten and widen the cylinder (when retaining the same strength), the mass of shielding is thicker for the same volume of material. However, if you are far enough underground, not really an issue.]

and I want to use less strong materials, that come from Earth,

"don't"?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/19/2019 03:45 am
To Paul 451.  Ouch that was a punctuation fail!  The high tensile carbon fiber used to hold together the compressed regolith blocks comes from Earth.  It is post tensioned construction.

As soon as possible, the carbon fiber is replaced with steel straps and rods manufactured in situ.

How interesting!  I'd never tried that out.  So the 12m is correct, if that is the standard I choose but I could select a larger one?  Gets hard to handle and assemble eventually, but that's good to know.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 05/19/2019 03:54 am
You can manufacture basalt fiber on Mars, too. Similar strength to carbon fiber but higher density.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/19/2019 06:56 am
You can manufacture basalt fiber on Mars, too. Similar strength to carbon fiber but higher density.

The melting point of basalt is several hundred degrees Celsius less than iron, so it will be less energy intensive to make than steel. (And vastly easier than carbon fibre.) It also requires fewer steps to make the fibre -- get basalt, melt, extrude, cool, spool -- and no extra ingredients, unlike steel production.

Flip side, you do also need the matrix for the composite; resin or concrete. And, once made, steel is easier to work with, easier to repair, etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: wes_wilson on 05/19/2019 12:35 pm
For my next little project, I'm thinking of a little stream , that goes from one habitat area to another.  The kind of streams you find in parks, or in botanical gardens.  A kind of linear park.  What might be nice to see?  Waterfalls and bubbly ponds?  My theme for my first habitat sector is Estepona.  I would expect the next sector to be resolutely chinese.  With chinese characters and a distinct chinese identity.  But what is a chinese identity?  I would like to avoid being overly Disney on this.
BTW Disney's were the names John Varley used for this type of underground habitats in his excellent novellas and novels about the Eights Worlds.  Potent stuff, those stories.

I think the Florida Aquarium in Tampa might be interesting structure to look at for streams inside a habitat area.  They have large walkways that are lined on one (or sometimes both) side(s) by moving water.  There's typically a chest height clear wall letting you see into the moving water and behind it there is area for plants and animals.  The water and glass keeps the people and plants/animals discretely separated.  It's beautiful, functional, and a nice way of interspersing walking areas with natural areas while also letting you use your space for streams to provide space for small free range animals which may be desired at some point (chickens, rabbits, goats, flightless birds).

https://www.lotsafunmaps.com/gallery.php?id=9060

While that above picture looks like it's outside.  The entire space is actually inside a dome and from the outside already looks like a martian habitat.
https://www.walterpmoore.com/projects/florida-aquarium





Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/19/2019 04:28 pm
I think @rakaydos is referring to something like this:
(http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg)
Same concept, but fixed in place, using the illusion to make meters of intervening radiation shielding "disapear" (the inside of the skylight would use a transparent shielding, like water) but not actually concentrating the light beyond martian Sol.

Any kind of focusing lens/mirrors/illusion won't work with diffuse light. (Even if you are "decompressing" the light back out at the output, you need highly directional light at the input to achieve the illusion/focus/whatever.)
You are miunderstanding the mechanics behind the illusion. The light isnt being compressed- if anything, it's being carefully decomplessed in such a way as it can be reversed to the original state at the destination.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 05/19/2019 07:12 pm
It occurs to me that the low level assembly of pressure vessels outside in Texas and Florida is good practice for in situ building of large settlement buildings on Mars. That materials for that could come flat-packed from Earth or made by melting down the thousands of tons of random iron-nickel meteorites littering the surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/20/2019 04:36 am
You can manufacture basalt fiber on Mars, too. Similar strength to carbon fiber but higher density.

The melting point of basalt is several hundred degrees Celsius less than iron, so it will be less energy intensive to make than steel. (And vastly easier than carbon fibre.) It also requires fewer steps to make the fibre -- get basalt, melt, extrude, cool, spool -- and no extra ingredients, unlike steel production.

Flip side, you do also need the matrix for the composite; resin or concrete. And, once made, steel is easier to work with, easier to repair, etc.
The matrix is the problem.  In a 50/50 typical composite the matrix will be quite expensive on Mars, since it's a hydrocarbon and therefore comes from very energy intensive electrolysis.   I expect plastics to be 5 to 6 times more expensive than steel.  Still, since steel is so dense there might not be all that much cost difference.
And plastic is competing with food for ressources, although again plastics would probably be made from biomass and not from the protein and carbohydrates.  So I guess someone would have to do the  MPa vs kJ of energy calculations to really know.  My guess is to go with steel, but I'm often wrong, so...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/20/2019 08:10 am
(http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg) (http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg)

in such a way as it can be reversed to the original state at the destination.

And that's what requires coherent light. Those straight parallel lines of incoming light in the top image.

Such a beastie is fine for bringing a bit of low light into a buried habitat for people to have some connection to the outside, but it won't be bright enough for plants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/20/2019 09:53 am
(http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg) (http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg)

in such a way as it can be reversed to the original state at the destination.

And that's what requires coherent light. Those straight parallel lines of incoming light in the top image.

Such a beastie is fine for bringing a bit of low light into a buried habitat for people to have some connection to the outside, but it won't be bright enough for plants.
what does that picture have to do with paired parabolic reflectors? Your persistence in using it convinces me you don't actually know what I'm talking about.
http://berkeleyphysicsdemos.net/sites/default/files/G%2B55%2B20.gif
The reason the illusion device works is because the direction of light doesn't matter. If it passes through the aperature, it will bounce off two mirrors and emerge, reversed but otherwise identically, from the other aperature. It will be just like having a thin window in the cealing- limited by the intensity of light at the upper aperature, but maintained exactly the same dispersion.

Edit: look, you know what a pinhole camera is, right? Where a small hole is effectively a lense? With a "pinhole" of 3 meters, projected on a have skylight 3m across, , you have photo-quality reproduction of the incoming light, from all directions.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/20/2019 10:28 am
(http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg) (http://thelowline.org/assets/images/about/project/carousel_technology/1.jpg)

what does that picture have to do with paired parabolic reflectors?

It involves paired parabolic reflectors.

Your persistence in using it convinces me you don't actually know what I'm talking about.

Since I've never "used it" before that last post, you might want to check the user-names on posts occasionally.

The reason the illusion device works is because the direction of light doesn't matter. If it passes through the aperature, it will bounce off two mirrors and emerge, reversed but otherwise identically, from the other aperature. It will be just like having a thin window in the cealing- limited by the intensity of light at the upper aperature, but maintained exactly the same dispersion.

Without the additional reflectors, as are in the mechanism in the diagram, the mirror-illusion alone won't do what you claim. It won't reflect the sky into a room, it can't pass light through metres of intervening shielding.

If you disagree, feel free to sketch out the lines-of-reflection for what you think will happen and post it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/20/2019 10:34 am
You can manufacture basalt fiber on Mars, too. Similar strength to carbon fiber but higher density.

The melting point of basalt is several hundred degrees Celsius less than iron, so it will be less energy intensive to make than steel. (And vastly easier than carbon fibre.) It also requires fewer steps to make the fibre -- get basalt, melt, extrude, cool, spool -- and no extra ingredients, unlike steel production.

Flip side, you do also need the matrix for the composite; resin or concrete. And, once made, steel is easier to work with, easier to repair, etc.
The matrix is the problem.  In a 50/50 typical composite the matrix will be quite expensive on Mars, since it's a hydrocarbon and therefore comes from very energy intensive electrolysis.   I expect plastics to be 5 to 6 times more expensive than steel.  Still, since steel is so dense there might not be all that much cost difference.
And plastic is competing with food for ressources, although again plastics would probably be made from biomass and not from the protein and carbohydrates.  So I guess someone would have to do the  MPa vs kJ of energy calculations to really know.  My guess is to go with steel, but I'm often wrong, so...

~55MJ/kg for HDPE. LDPE is more difficult to make as it requires higher pressures and temperatures.

Source is "Eco-Profiles of the European Plastics Industry" by I Boustead, 2005 (you can google it, I just can't copy-paste the URL due to issues.

Steel seems to be about 25MJ/kg, assuming oxgen is "free."

HDPE can be mixed with a suitable fibre so its native MPa may not be a good basis for comparison.

In terms of habitat construction, steel is a source of neutrons, even behind shielding (even on Earth, sitting inside steel gives you a neutron bath). HDPE is comparitively weak unless you go up to UHWMPE but all of it is a very effective neutron sponge, and the industry is just a tap-off of the methane production system.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/20/2019 11:37 am
If you disagree, feel free to sketch out the lines-of-reflection for what you think will happen and post it.
(http://berkeleyphysicsdemos.net/sites/default/files/G%2B55%2B20.gif)

Its been right here in the link, every time it's been mentioned.

Replace the coin with a skylight to a room below.

If that's not enough, go google "Pinhole camera", then come back and look at this image.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/20/2019 12:24 pm
If you disagree, feel free to sketch out the lines-of-reflection for what you think will happen and post it.
(http://berkeleyphysicsdemos.net/sites/default/files/G%2B55%2B20.gif)

Its been right here in the link, every time it's been mentioned.

Replace the coin with a skylight to a room below.

If that's not enough, go google "Pinhole camera", then come back and look at this image.

That's for projecting images, ie a cousin of the periscope. Diffuse light is a 2pi solid angle image. Anyway, if you need more light just increase the number of solar collectors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/20/2019 12:28 pm
If you disagree, feel free to sketch out the lines-of-reflection for what you think will happen and post it.
(http://berkeleyphysicsdemos.net/sites/default/files/G%2B55%2B20.gif)

Its been right here in the link, every time it's been mentioned.

Replace the coin with a skylight to a room below.

If that's not enough, go google "Pinhole camera", then come back and look at this image.

That's for projecting images, ie a cousin of the periscope. Diffuse light is a 2pi solid angle image. Anyway, if you need more light just increase the number of solar collectors.
And a 1:1 projection of the martian sky is all I'm asking for here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/20/2019 12:31 pm
If you disagree, feel free to sketch out the lines-of-reflection for what you think will happen and post it.
Its been right here in the link, every time it's been mentioned.
Replace the coin with a skylight to a room below.

[edit] Can you [/edit] sketch on a piece of paper and scan or photograph it? How does it pass light through a thick radiation shield? Hint: The mirror-toy is hollow and much, much wider than its aperture.

[Edit: Reduced dickishness.]

If that's not enough, go google "Pinhole camera", then come back and look at this image.

I've made pinhole cameras, I know how they work. They don't have 3m "pinholes", and they don't pass light through a shield.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/20/2019 12:55 pm
If you disagree, feel free to sketch out the lines-of-reflection for what you think will happen and post it.
Its been right here in the link, every time it's been mentioned.
Replace the coin with a skylight to a room below.

{sigh} You're too lazy to even sketch on a piece of paper and scan or photograph it? How does it pass light through a thick radiation shield? Hint: The mirror-toy is hollow and much, much wider than its aperture.

If that's not enough, go google "Pinhole camera", then come back and look at this image.

I've made pinhole cameras, I know how they work. They don't have 3m "pinholes", and they don't pass light through a shield.
If not drawing my own picture is "too lazy", what is "Not looking at the link the last three times It was posted?"

As I said the first time, fill the mirrored space with a visually-transparent material with radiation shielding properties, such as water.

As for the size of the pinhole in a pinhole camera, that isn't actually an issue. (https://www.quantamagazine.org/the-new-science-of-seeing-around-corners-20180830/)
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/20/2019 01:09 pm
Added some off-focus sightlines to demonstrate the viability of  a larger than pinhole sized aperature.

Edit: Also, I'm a bit short tempered today due to back pain and the resulting lack of sleep. I apoligise for any abrasiveness.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 05/20/2019 02:17 pm
A suggestion for Mars Hab Designers: Use modular layouts.

SpaceX will necessarily develop sophisticated ECLSS systems for Starship. They will be designed to accommodate a certain number of persons within a confined space, up to a max. volume.  Design each Mars module for the same number of people and within the specified max. volume, irrespective of habitat shape or materials. Employ standard production ECLSS units for your modules to cut the cost of developing the initial base village.

Modules built using ISRU can also adopt the same approach.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/20/2019 03:26 pm
As I said the first time, fill the mirrored space with a visually-transparent material with radiation shielding properties, such as water.

So why not just use a layer of water and skip the illusion mirror-toy? (Given the internal air-pressure, it's not like supporting the mass is an issue.) Or just use a tube the width of the "skylight" with a reflective wall? Why are you so determined to use this toy? I get that it's a neat effect, but that's all it is.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 05/20/2019 03:38 pm
As I said the first time, fill the mirrored space with a visually-transparent material with radiation shielding properties, such as water.

Which changes the angle of refraction.
Only when transitioning from marsair to glass to water, and from water to glass to habair. The internal reflections should maintain their relationship with each other.

So you're right, there will be some distortion of the skylight, with colors scattering much further than they would seem like they should. But the total light entering the hab should be the same (minus the absorption of the water, glass and mirrors) as the light striking the top aperture, from all angles.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 05/20/2019 04:00 pm
A suggestion for Mars Hab Designers: Use modular layouts.

SpaceX will necessarily develop sophisticated ECLSS systems for Starship. They will be designed to accommodate a certain number of persons within a confined space, up to a max. volume.  Design each Mars module for the same number of people and within the specified max. volume, irrespective of habitat shape or materials. Employ standard production ECLSS units for your modules to cut the cost of developing the initial base village.

Modules built using ISRU can also adopt the same approach.
A second reason for using modules with their own ECLSS is safety.

Each module should be equipped with airlock doors to isolate it in case of emergency. If one module becomes damaged and cannot maintain air pressure, personnel can seek shelter in the nearest unit and close the door behind them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 05/20/2019 07:59 pm
A suggestion for Mars Hab Designers: Use modular layouts.

SpaceX will necessarily develop sophisticated ECLSS systems for Starship. They will be designed to accommodate a certain number of persons within a confined space, up to a max. volume.  Design each Mars module for the same number of people and within the specified max. volume, irrespective of habitat shape or materials. Employ standard production ECLSS units for your modules to cut the cost of developing the initial base village.

Modules built using ISRU can also adopt the same approach.
A second reason for using modules with their own ECLSS is safety.

Each module should be equipped with airlock doors to isolate it in case of emergency. If one module becomes damaged and cannot maintain air pressure, personnel can seek shelter in the nearest unit and close the door behind them.
As the initial village grows, the capability to construct larger structural volumes may proceed more quickly than the capability to build sophisticated ECLSS units. In this circumstance, one could design larger volumes employing multiples of standard ECLSS units imported from Earth. For example, if a standard unit supports 25 people in one hab module, one could design a small auditorium for 200 people by employing 8 standard ECLSS units operating in parallel inside the HVAC ductwork.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 05/20/2019 09:37 pm
Continued from Reply #2216.
ECLSS units for hallways.

Hallways should also be designed as standard modules that employ standard ECLSS units. Hallways will allow personnel in shirtsleeves and equipment on carts to pass easily between habitats and other humanity modules. Each hallway section should have its own ECLSS unit so that it does not draw its clean air from the modules attached to it. Each hallway section should also have an airlock door at each conjoined module as it would serve as a place of refuge in an emergency.

Using this approach, consider the above example of an auditorium for 200 people. The auditorium could be a central location within the village with 8 hallways leading to it. Attendees could be seated in 8 sections with a hallway door located near each section. In case of emergency, people would evacuate into 8 different hallways, thus avoiding a jam-up at any one exit. The number of people in each hallway would match the capacity of the ECLSS unit attached to it. People could remain in the hall until the emergency is resolved or continue down the hallway into another hab.

   
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/21/2019 08:10 am
A suggestion for Mars Hab Designers: Use modular layouts.
SpaceX will necessarily develop sophisticated ECLSS systems for Starship. They will be designed to accommodate a certain number of persons within a confined space, up to a max. volume.  Design each Mars module for the same number of people and within the specified max. volume, irrespective of habitat shape or materials. Employ standard production ECLSS units for your modules to cut the cost of developing the initial base village.
Modules built using ISRU can also adopt the same approach.

Not necessarily. "ECLSS" isn't a single thing. It's a web of interconnected bits, each with their own quirks of maintenance, MTBF, consumables, power consumption, heat generation, etc. What's appropriate for a ship won't necessarily be suitable for a base and certainly not for a colony, and what works for a ship won't necessarily scale as you need.

For example, it's unlike that you'd use per-module CO2 scrubbing in a colony. You'd be using the agricultural spaces, with a centralised mechanical/chemical scrubber to handle diurnal and seasonal variation/imbalances. Each module might have emergency scrubbers, but they'd be short during (couple of people/couple of days) with extensive refurb required after use.

You'll have similar issues with water filtration and treatment. You need to dehumidify the air in every module, but that won't necessarily become drinking water (as on ISS or on Starship).

Given that ISRU is meant to be central to any large Mars settlement, there'll be central processing systems for air/water, and (as with a lot of smelting/manufacturing systems on Earth) it's often easier to dump untreated recovered/recycled material back into the manufacturing stream than to duplicate a filtration/purification/treatment system purely for the recycled material, and certainly not in every single module.

You might, for example, have a dehumidifier for each module (or each logical group of modules, each section of the settlement), but the recovered waste water might be pumped out to the central water filtration plant (that purified Mars water). OTOH, Urine from toilet systems will be kept for plants (although might require pre-treatment, certainly ongoing analysis for chemistry). Solid waste and grey water will each have their own treatment paths, and their own uses.

But that's not how you would build a ship system, because the ship is doing a full recyc of all sources of waste water to drinking water. Different needs, different systems.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 05/21/2019 12:16 pm
I suspect there will be a mishmash of ECLSS units that builds up over time. A number of early Starships will be used initially until at some point a purpose built unit for maybe 50 people is brought in, then there will be a lot of crop growing capacity added absorbing CO2 and some waste materials, then perhaps they will add in some improved units of a experimental design and before long 150 people will be wanting a four 50 person unit only to find that they will be getting a new 250 person unit part built on Mars. And so on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: spacenut on 05/21/2019 01:25 pm
Why not just use glass fish tanks or fresh water storage 3' or 1m deep above the habitable area.  The water would allow sunlight through for lighting and filter out radiation.  The tanks could have insulated doors that close over them at night to avoid freezing.    This would allow people in habitats to receive sunlight for natural lighting and used the water elevated above them for water pressure to their sinks and showers. below.  They are going to need water anyway.  Water can be fed through black solar water heaters the piped back into the tanks to keep water warm from the cold Mars atmosphere. 

In the greenhouse areas the elevated water tanks can grow algae and tilapia, waste would then be tapped from the bottom of the tanks to feed the hydroponic gardens below.  Again water circulated to keep warm through solar water heating pipes.  Also, again covered with insulated doors to keep it warm at night. 

No mirrors, no weird systems.  Water has to be stored for use or for growing fish and aquaponics.  Why not use the water for double duty by filtering out radiation while giving some natural light for aesthetics, and being elevated above living areas allowing natural gravity feeds to living areas and hydroponic areas?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 05/21/2019 11:48 pm
A suggestion for Mars Hab Designers: Use modular layouts.
SpaceX will necessarily develop sophisticated ECLSS systems for Starship. They will be designed to accommodate a certain number of persons within a confined space, up to a max. volume.  Design each Mars module for the same number of people and within the specified max. volume, irrespective of habitat shape or materials. Employ standard production ECLSS units for your modules to cut the cost of developing the initial base village.
Modules built using ISRU can also adopt the same approach.

Not necessarily. "ECLSS" isn't a single thing. It's a web of interconnected bits, each with their own quirks of maintenance, MTBF, consumables, power consumption, heat generation, etc. What's appropriate for a ship won't necessarily be suitable for a base and certainly not for a colony, and what works for a ship won't necessarily scale as you need.

For example, it's unlike that you'd use per-module CO2 scrubbing in a colony. You'd be using the agricultural spaces, with a centralised mechanical/chemical scrubber to handle diurnal and seasonal variation/imbalances. Each module might have emergency scrubbers, but they'd be short during (couple of people/couple of days) with extensive refurb required after use.

You'll have similar issues with water filtration and treatment. You need to dehumidify the air in every module, but that won't necessarily become drinking water (as on ISS or on Starship).

Given that ISRU is meant to be central to any large Mars settlement, there'll be central processing systems for air/water, and (as with a lot of smelting/manufacturing systems on Earth) it's often easier to dump untreated recovered/recycled material back into the manufacturing stream than to duplicate a filtration/purification/treatment system purely for the recycled material, and certainly not in every single module.

You might, for example, have a dehumidifier for each module (or each logical group of modules, each section of the settlement), but the recovered waste water might be pumped out to the central water filtration plant (that purified Mars water). OTOH, Urine from toilet systems will be kept for plants (although might require pre-treatment, certainly ongoing analysis for chemistry). Solid waste and grey water will each have their own treatment paths, and their own uses.

But that's not how you would build a ship system, because the ship is doing a full recyc of all sources of waste water to drinking water. Different needs, different systems.
You are correct for a colony as it grows. Modular approach is for setting up initial base quickly, like trailers in a mining camp. There will be inefficiencies that would be redesigned and incorporated as time allows.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/22/2019 10:34 am
Why not just use glass fish tanks or fresh water storage 3' or 1m deep above the habitable area.  The water would allow sunlight through for lighting and filter out radiation.  The tanks could have insulated doors that close over them at night to avoid freezing.    This would allow people in habitats to receive sunlight for natural lighting and used the water elevated above them for water pressure to their sinks and showers. below.  They are going to need water anyway.  Water can be fed through black solar water heaters the piped back into the tanks to keep water warm from the cold Mars atmosphere. 

In the greenhouse areas the elevated water tanks can grow algae and tilapia, waste would then be tapped from the bottom of the tanks to feed the hydroponic gardens below.  Again water circulated to keep warm through solar water heating pipes.  Also, again covered with insulated doors to keep it warm at night. 

No mirrors, no weird systems.  Water has to be stored for use or for growing fish and aquaponics.  Why not use the water for double duty by filtering out radiation while giving some natural light for aesthetics, and being elevated above living areas allowing natural gravity feeds to living areas and hydroponic areas?

It's important to have visibility through windows if they're meant to be windows in case of emergencies. You also want to be able to immediately see if there is window degradation or damage, which fish will make problematic.

Fish farms are very turbid due to phytoplankton, as I pointed out before, plus there's fish poo and uneaten fish food constantly falling to the bottom of the tank. You can work around these, but the actual number of fish is prohibitive - 10-50 per m3 for intensive farming.

http://vikaspedia.in/agriculture/fisheries/fish-production/culture-fisheries/types-of-aquaculture/intensity-of-inputs-and-stocking-density-based-aquaculture

Rather have clear water or ice between the acrylic sheets*. The fish tanks can be in a less critical spot and devoted to food production without complications. A few aquariums can be scattered in public areas for discrete additional shielding.

*Or probably transparent HDPE, much much easier to make and stronger.

https://www.techbriefs.com/component/content/article/tb/stories/blog/34309
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/25/2019 03:18 am
Above and below images of a colony node.
Only a few nodes would also connect to the transportation network, most travel would be on foot.
The smaller vehicles are taken from the Heathrow airport Ultra pod design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/26/2019 04:11 am
Is there any reason you have the interconnector tubes so long and narrow? Volume/area works better if they are shorter and wider, similarly, shielding would be more mass-efficient.
They are long and narrow to save on materials. The strain on the tanks goes up with the diameter

We were both wrong.

If you keep the same wall strength (burst pressure) and the same total mass of wall material, internal-volume & length are exactly inversely proportionally. Make the tube longer and narrower, or shorter and wider, and the mass and internal volume both remain the same. (I used a circular cylinder for simplicity, but I think the same should apply to an oval cylinder.)

So there's no particular advantage going short/wide, but there's also no advantage going long/narrow. You are better off just picking one diameter for your construction. 12m in your example. (Say four stories, perhaps split as two levels on two "road" levels with ~5m ceilings and a small volume below and above for shared utilities.)

This is exactly my reasoning behind cellular pressure vessels. If the pressure vessel efficiency is the same no matter what size it is, then choose a size that lets it do double duty as walls/floor and yields mass savings elsewhere in the structure. This will achieve even lower mass than this notional pressure cylinder+gravity floor system. Plus the shape is less awkward internally and has easier site prep than a huge monolithic cylinder.

(https://i.imgur.com/cqSH8sI.jpg)

As shown by the NASA lunar sphere study, a separate gravity floor (even a mass-optimized one) can be quite heavy. Once ISRU materials are being used, lighter designs that use less material will still be cheaper than heavy designs, all else being equal.

[I was right about the shielding being better with short/wide, though. Just as the wall thickness increases as you shorten and widen the cylinder (when retaining the same strength), the mass of shielding is thicker for the same volume of material. However, if you are far enough underground, not really an issue.]

Good, good. Let the scaling laws flow through you...  ;D

It's not sexy, but the math and physics don't lie. For the cheapest radiation shielding above ground, you want your structure to have an aspect ratio resembling a warehouse, not a skyscraper.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tywin on 06/09/2019 10:16 pm
Amazing work by HASSEL, this concept is beautiful...

https://youtu.be/AIrH01N9AsE

I hope we see someday...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 06/10/2019 03:59 pm
That's a very cool concept video.  I like the notion of separating out the radiation shielding from the structure of the actual habitat, as that seems to provide a certain amount of flexibility (although it also means natural light will be hard to come by).

The one-wheeled reconfigurable robots are neat, and remind me a lot of the modular units that are used for heavy transport (https://www.youtube.com/watch?v=MyW-AqTdcwY), although I'm dubious of the practicality of the single-wheel design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/10/2019 09:25 pm
Amazing work by HASSEL, this concept is beautiful...
https://www.youtube.com/watch?v=AIrH01N9AsE

How do those single wheeled units steer themselves? Unicycle-bots steer by leaning the wheel using movable-weights and letting torque force turn them, or by using a gyroscope to overcome tyre friction to twist the bot. Those fat tyres don't lean and have too much ground-friction to twist on the spot.

The only thing I can imagine is if they use "smart wheels", where you have separately driven rollers inside the main tyre. That increases your mechanical complexity too much (IMO).

Using a pair of dual-wheel sub-assemblies as in the Mammoet heavy mover means four wheels on each section. Turn the wheels 90 degrees to the deck and you have a steerable 4-wheel-drive vehicle. Let that be your smallest independent section. Link the assemblies together for larger units (like those shown in the video) to add cargo-capacity, stability, flexibility, etc. But those sections can be stripped to their sub-units to replace damaged components, since every part is standardised and swappable.

Hard connecting those 4W units gives a solid-deck vehicle. Flexible links gives extra mobility in the vertical, horizontal, twist, or all three, depending on the job. Units with bad motors get turned into trailers (if their battery-packs still work, range-extender trailers) on faster, graded roads. Reduced capacity battery packs get integrated into base infrastructure or solar charging-stations along trafficked routes and at mine-sites.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/11/2019 12:47 am
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.

Looks to be about 1000m^3 of pressurized volume, but the shell looks to be pretty large, maybe on average 2 meters thick and 1300 square meters in area, with a density of about 2kg/liter, that means we're talking about 5000 metric tons of regolith that needs to be melted using microwaves. It takes about 1100kJ/kg to heat up the regolith (with we consider it similar to basalt), and another 500kJ/kg to melt it, total of 1.6MJ/kg or about 7*10^12 Joules. The rovers with little on-board solar panels or something are supposed to do this autonomously? That's the ~same amount of energy to fuel up a Starship...

...or you could just use sand bags.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 06/11/2019 12:55 am
...or you could just use sand bags.

(https://sc01.alicdn.com/kf/HTB1zJ0WnxHI8KJjy1zbq6yxdpXaO/MIL8-Hesco-Barriers-Wall-Hesco-Bastion-For.jpg_350x350.jpg)
(https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/US_Navy_090411-N-8547M-025_Seabees_assigned_to_Naval_Mobile_Construction_Battalion_%28NMCB%29_5_lift_a_HESCO_barrier_into_alignment_during_a_project_at_Camp_Bastion.jpg/1024px-thumbnail.jpg)

https://en.wikipedia.org/wiki/Hesco_bastion
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/11/2019 01:01 am
Cool design, but I don't really see the point of the 3d printed shell.

It was the central topic for the contest. "Just don't, it's stupid," wouldn't get you very far.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Tulse on 06/11/2019 01:49 pm
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/11/2019 01:54 pm
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.
The internal pressure of the hab easily supports the sandbags. In fact, the sandbags can slightly reduce the tensile stress on the pressurized hab by helping to restrain the pressure (although this is a relatively small effect and you can't practically take advantage of it operationally, besides perhaps a small reduction in creep).

3D printing is generally bad for building large things.

Effectively, we're talking about 3D printing at a large scale with lava. Has anyone ever 3D printed any buildings with molten rock on Earth?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/11/2019 01:56 pm
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.

Sandbags can form arches. The trouble with sandbags is that they are floppy things easy for humans to work with but not suited to robotics on a remote planet. Therefore not ideal as a way to build the first base.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/11/2019 01:58 pm
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.

Sandbags can form arches. The trouble with sandbags is that they are floppy things easy for humans to work with but not suited to robotics on a remote planet. Therefore not ideal as a way to build the first base.
I highly doubt what was illustrated in this video is more practical.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/11/2019 02:12 pm
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.

Sandbags can form arches. The trouble with sandbags is that they are floppy things easy for humans to work with but not suited to robotics on a remote planet. Therefore not ideal as a way to build the first base.
I highly doubt what was illustrated in this video is more practical.

Never said those Claptrap-bots were. Just pointing out one of the reasons why space agencies are going for 3D printing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/11/2019 02:15 pm
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.

Sandbags can form arches. The trouble with sandbags is that they are floppy things easy for humans to work with but not suited to robotics on a remote planet. Therefore not ideal as a way to build the first base.
I highly doubt what was illustrated in this video is more practical.

Never said those Claptrap-bots were. Just pointing out one of the reasons why space agencies are going for 3D printing.
I'm not convinced 3D printing (which I work with all the time) at this scale is harder to work with than sandbags for robots. Additionally, you can integrate the sandbags into the exterior of the habitat, in which case the robot just has to pour (sifted) regolith into the top.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 06/11/2019 04:07 pm
I thought I read somewhere that passable bricks could be manufactured using graded regolith and a hydraulic press. I would have thought that would require a lot less energy than the molten lava printing and might be also be more amenable to robotic construction. As for the roof perhaps an inflatable Kevlar structure with a few supporting beams with regolith piled on top might work. Starting the construction in a depression or crater and back filling might also help.

After a little while they might even be able to manufacture the beams on the surface out of Iron formed using the carbonyl process, as there appears to be some metallic iron and nickel on the surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 06/11/2019 04:56 pm
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.

Sandbags can form arches. The trouble with sandbags is that they are floppy things easy for humans to work with but not suited to robotics on a remote planet. Therefore not ideal as a way to build the first base.
That's the reason Hesco went with wire reinforced foldable cells, sized for filling with a backhoe.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/12/2019 01:41 am
The general downside to regolith shielding is that, as discussed a few pages back, it increases radiation levels for the first 1.5m or so. You only see significant shielding above 3m thickness.



Effectively, we're talking about 3D printing at a large scale with lava. Has anyone ever 3D printed any buildings with molten rock on Earth?

As part of the contest, the teams have to demonstrate their 3D printing method on a large scale.

However, heat-sintered material doesn't have to be completely molten. Whatever component has the lowest melting points becomes, in effect, a binder for the bulk. Moreso, given the results for compressed bricks, they probably aren't melting any component, they may just be heating enough to create a chemical bonding between certain minerals.



I thought I read somewhere that passable bricks could be manufactured using graded regolith and a hydraulic press.

Yeah, if you have to use regolith, that makes more sense to me. Blocks are easier to handle, even by bots, and can create self-supporting structures. But rammed-regolith bricks might have been excluded by the terms of the contest.

Although one method I found lends itself to compression combined with extrusion, which allows additive manufacture. link (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5430746/) The extruded material bested concrete in bending strength, although lost a lot of compressive strength.

[edit: Read that wrong. It required lower compression during manufacture for the same high bending strength result.]

Aside: I did notice that the regolith pre-treatment includes heating to 600°C for 12hrs. Not exactly low energy. Although that might have been to better match the simulant to actual regolith (if I'm reading it right.)

there appears to be some metallic iron and nickel on the surface.

Does anyone know if there is metallic fines in the Martian regolith? I was trying to find a decent reference for this a few months back and kept coming up blank. There are references to whole metallic meteorites on the surface, as found by Curiosity, and bulk asteroidal remains buried in large impact craters, but I was looking for something on cumulative metallic fines (as in lunar regolith.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/12/2019 02:48 am
Can't say that I know this but you should expect any metallics fine to have been oxidized a long time ago.  Even today there is some humidity, and the finer the fines the faster they rust.  Oxygen largely dominates the crust composition, after all.  Might be some gold dust here and there :-)

There have been some papers proposing that fine iron ore particles (Fe2O3)  can be rammed into pretty good bricks, but to know, we'll have to go.  Compressed regolith blocks, similar to Compressed Earth blocks, should also be pretty low energy building materials.  What I would really like to know is if the carbonates identified by THEMIS could be used for concrete.  That would simplify things no end!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/12/2019 03:07 am
The general downside to regolith shielding is that, as discussed a few pages back, it increases radiation levels for the first 1.5m or so. You only see significant shielding above 3m thickness.

A good argument not to use a 3D printed shell like that, then. Easier to stack regolith higher than build a 3 meter thick lava building.

...additionally, I question the assumptions of that simulation. Simulating on Mars proper isn't really much harder. Just fire up Oltaris, it's one of the options.

Effectively, we're talking about 3D printing at a large scale with lava. Has anyone ever 3D printed any buildings with molten rock on Earth?

As part of the contest, the teams have to demonstrate their 3D printing method on a large scale.

However, heat-sintered material doesn't have to be completely molten. Whatever component has the lowest melting points becomes, in effect, a binder for the bulk. Moreso, given the results for compressed bricks, they probably aren't melting any component, they may just be heating enough to create a chemical bonding between certain minerals.
...
The video in question shows molten material being extruded, not just sintered. Sintering is more realistic, I agree.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/12/2019 12:06 pm
Does anyone know if there is metallic fines in the Martian regolith? I was trying to find a decent reference for this a few months back and kept coming up blank. There are references to whole metallic meteorites on the surface, as found by Curiosity, and bulk asteroidal remains buried in large impact craters, but I was looking for something on cumulative metallic fines (as in lunar regolith.)

Unlikely. Troilite (FeS) occurs as grains and appears metallic but is nonmagnetic. Lunar dust has a glassy shell speckled with metallic iron. About 1.0% wt in mare, 0.7% in highlands.

Otherwise, Martian dust is a mixture of magnetite and titanomagnetite (some Ti substitution for Fe), and haematite, which is antiferromagnetic at typical Martian temperatures. So most Martian dust can be acted on with induced magnetic fields.

The general downside to regolith shielding is that, as discussed a few pages back, it increases radiation levels for the first 1.5m or so. You only see significant shielding above 3m thickness.

A good argument not to use a 3D printed shell like that, then. Easier to stack regolith higher than build a 3 meter thick lava building.

...additionally, I question the assumptions of that simulation. Simulating on Mars proper isn't really much harder. Just fire up Oltaris, it's one of the options.

The thicknesses Paul451 is quoting comes directly from my OLTARIS simulations. The default OLTARIS Martian regolith has less elemental Fe than I've seen quoted in a lot of literature. Fe worsens the shielding effectiveness because it makes helluva lot of secondaries. Besides, the 200g/cm2 plateau is confirmed by upper atmospheric radation experiments which take neutron spalling into account.

https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016SW001402

1.5m of loose regolith is rougly 150g/cm2 at typical earth sand densities. Compacted, it may be up to 1.5g/cc and therefore the minimum can be 1m. Turned into dirty glass, 2g/cc or more.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/12/2019 12:52 pm
I wouldn’t second-guess the makers of Oltaris for regolith composition and then extrapolate that second-guessing to broad conclusions.

It’s also feasible to be picky about regolith, i.e. choosing lighter colored regolith. Or, for instance, gypsum-rich regolith which is common in some spots and is water-rich.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 06/12/2019 01:07 pm
Instead of cement how about casting blocks of ice. Ice should be better for radiation? Pour liquid water into forms and let it freeze. Would it freeze before it boiled away?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/12/2019 01:30 pm
Instead of cement how about casting blocks of ice. Ice should be better for radiation? Pour liquid water into forms and let it freeze. Would it freeze before it boiled away?
Keep it in the forms, then you don't have to worry about it sublimating.

Ice would be superior. IF you've got lots of it.

NASA has funded this already, and it strikes me as a lot more feasible (and fundamentally better, from a radiation shielding perspective) than the lava 3D printing:
https://www.nasa.gov/feature/langley/a-new-home-on-mars-nasa-langley-s-icy-concept-for-living-on-the-red-planet
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 06/12/2019 04:00 pm
How about pouring mud? At least 80% dust and gravel. Water being the cement in that "concrete". I am assuming they will have cubic km of water available.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 06/12/2019 04:16 pm
How about pouring mud? At least 80% dust and gravel. Water being the cement in that "concrete". I am assuming they will have cubic km of water available.

I thought radiation shielding wise it was better to have light atoms like water?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/12/2019 04:21 pm
How about pouring mud? At least 80% dust and gravel. Water being the cement in that "concrete". I am assuming they will have cubic km of water available.

I alternated layers of water-ice and regolith in OLTARIS, 50/50 by weight. Worked surprisingly well. As long as there are hydrogens to mop up the secondaries and neutrons.

I've also added a new Mars regolith material in OLTARIS using chemical abundances from Gusev Crater soil (not dust, as that's different). I suspect differences in dose will be small.

https://www.hou.usra.edu/meetings/marsdust2017/pdf/6027.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 06/12/2019 08:28 pm
We may want to know what particle sizes and types will work best to make mars bricks from regolith. We would start with rock and pebble screens, as suggested by RobotBeat. If we want even smaller particles we could employ an air classifier, which is a cyclone separater such as the one shown below.

The cyclone is a funnel-shaped device that spins air at the top end to create a vortex. Then dust-laden air is introduced into the airstream so that low-density particles spin out the top and higher density materials drop through the bottom. The particle size separation point is set by airstream velocity and density of the air. Mars low air density would require operating in an enclosed space to maintain higher air pressure. A cyclone  is not as efficient as some other types of separators, such as an electric precipitator, but uses less power.

The type of dust subject to experimentation would vary according to the location of the sourced regolith.

ISTM we might discover the right regolith and particle size combination to create mars bricks just by compression, with little or no adhesive imported from Earth.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/13/2019 08:11 am
We may want to know what particle sizes and types will work best to make mars bricks from regolith. We would start with rock and pebble screens, as suggested by RobotBeat. If we want even smaller particles we could employ an air classifier, which is a cyclone separater such as the one shown below.

The cyclone is a funnel-shaped device that spins air at the top end to create a vortex. Then dust-laden air is introduced into the airstream so that low-density particles spin out the top and higher density materials drop through the bottom. The particle size separation point is set by airstream velocity and density of the air. Mars low air density would require operating in an enclosed space to maintain higher air pressure. A cyclone  is not as efficient as some other types of separators, such as an electric precipitator, but uses less power.

The type of dust subject to experimentation would vary according to the location of the sourced regolith.

ISTM we might discover the right regolith and particle size combination to create mars bricks just by compression, with little or no adhesive imported from Earth.




Magnetic separation would also be a simple way to extract magnetite-rich dust particles.

Recently, I've wondered if the dark dunes we see in certain regions of Mars are also partly due to an interaction of the local magnetic fields and prevailing winds. The darker dust (magnetite-rich) is more strongly attracted to magnets as seen on the various rover dust experiments.

As for brick manufacture by compression, the article I've linked to before describes doing this with Mars 1-a regolith simulant. The catch is that this only works for dust, not soil, so sources of deep dust are a requirement. Plus the fact that Mars simulant doesn't quite match actual Mars dust.

https://www.popsci.com/mars-soil-bricks/
https://www.nature.com/articles/s41598-017-01157-w

Also, I created a material database in OLTARIS based on Gusev crater samples. As I expected, the shielding benefit is marginally worse than the default Mars regolith, probably due to the higher iron content making more secondaries. But at great thicknesses, the effect is far worse than I expected. I also noticed that the default Mars regolith had a water content of 7.4%, whereas the Gusev crater soil was generally bone dry (my mix has 0.1%).

As you can see, the OLTARIS default when compared with typical Martian soil, the radiation protection is overall worse for realistic soil. Depths of at least 5m with uncompacted soil are required for protection. (Note: these are free space values at solar Minimum, with a representative 40g/cm2 of atmospheric shielding - halve the dose to represent the shielding of Mars).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 06/13/2019 05:58 pm
I think they need to pump some water into that dry regolith to improve its shielding properties. In addition they will need a lot of batteries to help even out the electricity supply at night. The more the base grows the greater the need for power and the more batteries that will be needed. Lithium batteries. I suggest all of the Lithium batteries are installed directly above the living accommodation as the Lithium will be very good as a radiation shield.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/13/2019 06:07 pm
I suggest all of the Lithium batteries are installed directly above the living accommodation as the Lithium will be very good as a radiation shield.

But is radiation good for lithium?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 06/13/2019 06:21 pm
I suggest all of the Lithium batteries are installed directly above the living accommodation as the Lithium will be very good as a radiation shield.

But is radiation good for lithium?
I'm sure its much better for lithium than for people. People are intricate molecular machines whereas batteries for the most part simply rely on the bulk properties of lithium salts and a few other chemicals.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/13/2019 07:12 pm
I suggest all of the Lithium batteries are installed directly above the living accommodation as the Lithium will be very good as a radiation shield.
But is radiation good for lithium?
I'm sure its much better for lithium than for people. People are intricate molecular machines whereas batteries for the most part simply rely on the bulk properties of lithium salts and a few other chemicals.

Unless the radiation breaks down those salts, accelerating the degradation that reduces battery capacity. I'm curious whether lithium batteries have that kind of issue in space probes. Are there specific formulations required for radiation exposure?

[Only research I can find is on brief but high radiation exposures, not lower continuous. Although I did note that the lithium is stored as an iron salt. LiFePO₄. Iron bad.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 06/14/2019 07:19 am
[Only research I can find is on brief but high radiation exposures, not lower continuous. Although I did note that the lithium is stored as an iron salt. LiFePO₄. Iron bad.]

For a battery a short but high exposure should be a good model. Batteries don't have a repair mechanism like living cells have. For a human short but high is a very bad model because of repair mechanisms.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/14/2019 01:10 pm
Lithium batteries don’t give a crap about the very low radiation levels on the Martian surface.

It won’t make a lick of difference to them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/14/2019 01:16 pm
I suggest all of the Lithium batteries are installed directly above the living accommodation as the Lithium will be very good as a radiation shield.
But is radiation good for lithium?
I'm sure its much better for lithium than for people. People are intricate molecular machines whereas batteries for the most part simply rely on the bulk properties of lithium salts and a few other chemicals.

Unless the radiation breaks down those salts, accelerating the degradation that reduces battery capacity. I'm curious whether lithium batteries have that kind of issue in space probes. Are there specific formulations required for radiation exposure?

[Only research I can find is on brief but high radiation exposures, not lower continuous. Although I did note that the lithium is stored as an iron salt. LiFePO₄. Iron bad.]

The ISS has lithium batteries. Radiation damage is not an issue. Yeah, I was also considering lithium batteries for shielding, but yeah, iron bad*. Not to mention all the jacketing of the battery cells, the wiring and all the other stuff. However, there are other battery formulations: lithium-manganese-oxide would be fairly good (though largely obsolete nowadays), and the lithium salt is contained in an organic solvent - ethylene carbonate (CH20)2CO, or something similar. The anode is carbon. Other formulations include the familiar cobalt, as well as nickel, titanium and aluminium. Aluminium offers the best energy storage density, but titanium offers the best life.

Looking ahead, lithium-ceramic batteries look like they will become a lot more commonplace, and are safe. But there's very little shielding benefit from the actual lithium: typical batteries are only like 1% lithium in weight.

Lithium metal hydride is one of the best radiation-absorbing materials out there. It could be used as part of an fuel cell energy cycle, especially for rovers.

*One of the first insights into cosmic radiation was the discovery that being inside a steel vessel, eg a ship, created an increase in background neutrons. That's how bad iron is.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/14/2019 01:24 pm
BTW, there’s a paper floating around that says lithium hydride is like better than methane. It’s unfortunately not true from what I can tell from other sources. It’s some kind of mix up, but several papers repeat that figure, so it’s important to double check it.

Lithium hydride isn’t a BAD shielding material, mind you, it’s just not nearly as good as is in that one graph.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/14/2019 03:04 pm
BTW, there’s a paper floating around that says lithium hydride is like better than methane. It’s unfortunately not true from what I can tell from other sources. It’s some kind of mix up, but several papers repeat that figure, so it’s important to double check it.

Lithium hydride isn’t a BAD shielding material, mind you, it’s just not nearly as good as is in that one graph.

It's important to remember that radiation transport codes have been continually refined, and that there are different ones. Methane is great, but requires cryogenic storage. Lithium hydride has its own issues, no doubt.

But I think it's pretty clear now that you either use water or polyethylene to shield large habitats, or you dig very deep.

Also, most calculations and graphs you see are for slabs. Spheres (which I use) model the effect of secondaries hitting back and forth between the walls. Not an issue for thin shielding, but it makes a huge difference for thick shields. If you just anchored yourself next to a thick slab, you'd be fine because the secondaries would shoot straight off into space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 06/14/2019 09:10 pm
Perhaps similar to the HASSEL concept without the printing, a deployable framework that the pressurized hab modules can fit under, that you can then dump regolith on? Perhaps with a series of baffles going down the sides to keep all the regolith from sliding off?

Sure you still need several meters of regolith for it to be "safe", but at least it's way easier than printing it. How much structural mass would you need to hold up all that regolith (and thus could it work)? Perhaps it could be sort of like the dirt bags, but with 3m deep dirt bags suspended and/or supported by the structure?

Not great for long term hab building but might be a good quick fix for short term setup until you can start building more sanely (vs 3d printing) from local materials.

You'd need a robo-excavator with enough reach to get to the top of the bags on the top of the structure (or perhaps a series of Archimedes screws), and probably some kind of robo-crane to help erect the thing (unless it could be pneumatically actuated into position, and then once in position unable to collapse due to some kind of locking mechanism).

I suspect it's not worth the effort unless you can do it remotely before humans arrive, though.

Perhaps an easier option, is to dig a pit to place the hab in, then just drop some beams across the top of it to support the bags (rather than some kind of pop up structure), and use regular old bags (you might even be able to use off the shelf ones if they hold up to the Martian environment, and just do multiple layers of bags to get to the needed regolith depth). You might even be able to use the hab to help support the weight by having some built in vertical structural supports for the beams to cross, that just transfer load straight down underneath the hab. Still easier than a hab that can support 3m of regolith directly across it's entire surface, right?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/14/2019 09:24 pm
Maybe just an excavator. Keep piling on regolith. 2 meters. 4 meters. 8 meters deep.
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 06/14/2019 10:19 pm
But I think it's pretty clear now that you either use water or polyethylene to shield large habitats, or you dig very deep.
Really? IIRC the usual figure suggested to emulate the radiation shielding of Earths atmosphere is 3m, or 9.85 feet.

That's roughly 1 storey of an apartment block.
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 06/14/2019 10:51 pm
>
Really? IIRC the usual figure suggested to emulate the radiation shielding of Earths atmosphere is 3m, or 9.85 feet.

That's roughly 1 storey of an apartment block.

Or the roof of what was once called an underground house.
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 06/15/2019 07:31 am
>
Really? IIRC the usual figure suggested to emulate the radiation shielding of Earths atmosphere is 3m, or 9.85 feet.

That's roughly 1 storey of an apartment block.

Or the roof of what was once called an underground house.
Of course it can be argued the radiation dose you got getting there was so large why bother with shielding when so much of the damage has already been done on the trip out.

That was why I liked the asteroid re-direct mission so much.

A big enough asteroid has all the shielding you need in orbit already there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/15/2019 10:17 am
Perhaps similar to the HASSEL concept without the printing, a deployable framework that the pressurized hab modules can fit under, that you can then dump regolith on? Perhaps with a series of baffles going down the sides to keep all the regolith from sliding off?

Sure you still need several meters of regolith for it to be "safe", but at least it's way easier than printing it. How much structural mass would you need to hold up all that regolith (and thus could it work)? Perhaps it could be sort of like the dirt bags, but with 3m deep dirt bags suspended and/or supported by the structure?

Not great for long term hab building but might be a good quick fix for short term setup until you can start building more sanely (vs 3d printing) from local materials.

I think the KISS solution is just pre-fabricated, bolt together framing and structural panels, like a pre-fab steel building. Initially these would be brought from Earth and later factory-built on Mars (but you still want pre-fab for ease of setup and transport to the site). Using bolts seems old-fashioned but they have the same advantage as on Earth: faster and more reliable assembly because there's no need for on-site welding and inspections.

These structures would engineered to act as both a cellular pressure vessel while pressurized, and a gravity structure while unpressurized. Both loads are of similar magnitude so this should be mass-efficient. On top is placed regolith shielding (for office/factory/LED grow space) or water shielding (for parks/greenhouses), with mechanically stabilized earth regolith on the sides. This would allow for long-term structures, not just temporary.

Mechanically stabilized earth:

https://www.youtube.com/watch?v=0olpSN6_TCc


Quote
You'd need a robo-excavator with enough reach to get to the top of the bags on the top of the structure (or perhaps a series of Archimedes screws), and probably some kind of robo-crane to help erect the thing (unless it could be pneumatically actuated into position, and then once in position unable to collapse due to some kind of locking mechanism).

I'm tempted by the idea of a temporary "scaffold" cellular inflatable that allows assembly to proceed in a shirt-sleeve environment, but it also seems like overkill. The "scaffold" would be more expensive than the building! You'd need some design that can be removed afterwards and reused, or you need inexpensive and long-lived inflatable technology that can be simply integrated into the building's pressure envelope.

Quote
Perhaps an easier option, is to dig a pit to place the hab in, then just drop some beams across the top of it to support the bags (rather than some kind of pop up structure), and use regular old bags (you might even be able to use off the shelf ones if they hold up to the Martian environment, and just do multiple layers of bags to get to the needed regolith depth). You might even be able to use the hab to help support the weight by having some built in vertical structural supports for the beams to cross, that just transfer load straight down underneath the hab.

Convergent evolution. Whether you're digging down or building up, the result is the same. :)

The terrain often won't be nice and flat, so you may be digging down on one side and building up on the other (though with cellular pressure vessels you can also do a "split level" and terracing approach). Obviously to minimize cost you don't want to excavate any more/less than is needed to build the wall and roof shielding.


Quote
Still easier than a hab that can support 3m of regolith directly across it's entire surface, right?

Nah that part's easy, especially in 38% gravity. The pressure forces of a nominal ~0.8 atm internal atmosphere are still far higher. A grid of I-beams that can hold that much pressure in tension will have no problems acting as a gravity structure holding up 3 meters of regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/15/2019 11:06 am
I think they need to pump some water into that dry regolith to improve its shielding properties.

Is that better or worse shielding-wise than putting all the water in one layer on the bottom (say, in a gravity-fed water tower on the 'top floor')? H2O is expensive, so if it can be conserved and that geometric configuration yields better shielding properties, all the better.

Also this eliminates the risk of the water sublimating away and degrading shield performance over time. No need for airtight bags/forms, low pressure atmospheres, water vapor scavenging, etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/15/2019 09:32 pm
The first SpaceX Mars base, will eventually have six ships.

Solar panel rolls. 4, wide. About 150m per roll seems reasonable?  Or too much friction?
Pulled out by a remotely controlled vehicle.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/15/2019 10:12 pm
Solar panel rolls. 4, wide. About 150m per roll seems reasonable?  Or too much friction? Pulled out by a remotely controlled vehicle.
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1565092;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1565092;image)

Instead of dragging the thin delicate solar arrays over the ground, why not have the spool on the vehicles as it unrolls? You must have a way to carry the spools from the lander, hence some kind of grabber/carrier on the vehicles, so just unspool as the vehicle drives out. No friction (or rather the friction helps unroll the panel).
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 06/15/2019 10:45 pm
Solar panel rolls. 4, wide. About 150m per roll seems reasonable?  Or too much friction? Pulled out by a remotely controlled vehicle.
(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1565092;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1565092;image)

Instead of dragging the thin delicate solar arrays over the ground, why not have the spool on the vehicles as it unrolls? You must have a way to carry the spools from the lander, hence some kind of grabber/carrier on the vehicles, so just unspool as the vehicle drives out. No friction (or rather the friction helps unroll the panel).

https://youtu.be/3YuSZvaP-9U
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/15/2019 11:00 pm
[...]

I was familiar with that, and that's exactly what I consider the wrong way around. (Especially that one, it's already on a freakin' trailer, just pull the anchor end from the back of the trailer and tow the whole trailer forward. No dragging. Also, no unhitching.)

You'll notice they only deploy it on very forgiving surfaces.

[Edit: To be fair to them, they are deploying from the side of the trailer, using the length to add width to the panels. However, IMO, adding a pivot on the trailer to turn the spool side-on during deployment would be a better long term solution than dragging the array over the ground and thus always being limited to soft surfaces. Road-width is obviously less of an issue on Mars, so not entirely relevant.]

[Edit 2: "Model 451", am I famous now?]
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/16/2019 12:41 am
Too brilliant!

This deserves to be named the model 451.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/16/2019 12:51 am
A better image of the stake down bar.

Two stakes into the ground, then just drive off slowly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/16/2019 03:36 am
Cool design, but I don't really see the point of the 3d printed shell. The only point of it seems to be radiation shielding and maybe some thermal control. Actually melting that much regolith seems insane because it's totally unnecessary. Sand bags placed over the habitat would accomplish the same thing with FAR less energy input.
How do you support the sandbags on top of the hab?  3D printing gives a solid rigid structure, and allows the hab to be a lightweight inflatable.

Sandbags can form arches. The trouble with sandbags is that they are floppy things easy for humans to work with but not suited to robotics on a remote planet. Therefore not ideal as a way to build the first base.
That's the reason Hesco went with wire reinforced foldable cells, sized for filling with a backhoe.

Speaking of "drive to deploy" mechanisms, HESCO has a neat one:

https://www.youtube.com/watch?v=GTZscYmBXco

I mentioned reinforced earth upthread, and (no surprise) HESCO concertainers have converged on a design with similar geometry and materials. :)

I wonder if it would be possible to make a version of this with all polymer materials? This would reduce secondary radiation at the surface (which could cause accelerated degradation of the geopolymers), and might reduce mass too.

I'm a big proponent of designs that locate the thermal insulating layer on the outside of the shielding wall, thereby making it do double duty as a thermal mass battery backup. If the shield mass is cold-soaked it becomes a thermal liability in low-power/low-heat emergency situations, but if the thermal mass is maintained at room temperature it becomes a thermal asset that buys troubleshooting time, or just time to wait out the storm. Ideally this outer thermal layer would employ both passive solar and switchable insulation, so it superinsulates at night and opportunistically soaks up heat during the day (care must be taken here to ensure a 'fail-safe' thermal design).
Title: Re: Envisioning Amazing Martian Habitats
Post by: john smith 19 on 06/16/2019 05:26 pm
There is an old NASA Tech Briefs item about using cut cardboard to make up boxes with stick out tabs that lock into other boxes to form walls.

Ship the flat sheets to planet, fold up (manually or by machine), fill with local regolith and stack.

Obviously not air tight but solid enough to provide heat and radiation shielding.

I think it dates from the 70's.

Not very pretty but quite flexible and good for creating a fair amount of shielded space fairly quickly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/19/2019 08:22 am
But I think it's pretty clear now that you either use water or polyethylene to shield large habitats, or you dig very deep.
Really? IIRC the usual figure suggested to emulate the radiation shielding of Earths atmosphere is 3m, or 9.85 feet.

That's roughly 1 storey of an apartment block.

Last I checked, the elemental composition of the Earth's atmosphere did not include 20%wt iron. ;) Jokes aside, iron is pretty bad: if you sit in an iron structure on Earth (eg in a ship) you get a slight neutron bath from the cosmic radiation hitting the iron and spalling. The radiation dose goes down (fewer milligrays), but I am quoting everything in effective dose, millisieverts, where neutrons are rated as 20x more damaging to organic matter than ionised particles.

The real problem is that cosmic radiation does not just "pass through and get absorbed by the surface." The ground is made of the same stuff as the regolith shielding, so what is happening in addition to the effect of the iron is that secondary particles are emitted by the floor are bouncing back into the hab.

A polyethylene or water liner will improve this quite significantly. You may have noticed that the Mars X-House and Ice House designs both feature water or polyethylene shielding on the floor of the habitat. This is why.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 06/21/2019 09:20 am
But I think it's pretty clear now that you either use water or polyethylene to shield large habitats, or you dig very deep.
Really? IIRC the usual figure suggested to emulate the radiation shielding of Earths atmosphere is 3m, or 9.85 feet.

That's roughly 1 storey of an apartment block.

Last I checked, the elemental composition of the Earth's atmosphere did not include 20%wt iron. ;) Jokes aside, iron is pretty bad: if you sit in an iron structure on Earth (eg in a ship) you get a slight neutron bath from the cosmic radiation hitting the iron and spalling. The radiation dose goes down (fewer milligrays), but I am quoting everything in effective dose, millisieverts, where neutrons are rated as 20x more damaging to organic matter than ionised particles.

The real problem is that cosmic radiation does not just "pass through and get absorbed by the surface." The ground is made of the same stuff as the regolith shielding, so what is happening in addition to the effect of the iron is that secondary particles are emitted by the floor are bouncing back into the hab.

A polyethylene or water liner will improve this quite significantly. You may have noticed that the Mars X-House and Ice House designs both feature water or polyethylene shielding on the floor of the habitat. This is why.

I may have missed it further back, but how much polyethylene is needed as oppose to water?
Polyethylene can be made in to nicer structural shapes across better temperatures than water can...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/21/2019 03:02 pm
But I think it's pretty clear now that you either use water or polyethylene to shield large habitats, or you dig very deep.
Really? IIRC the usual figure suggested to emulate the radiation shielding of Earths atmosphere is 3m, or 9.85 feet.

That's roughly 1 storey of an apartment block.

Last I checked, the elemental composition of the Earth's atmosphere did not include 20%wt iron. ;) Jokes aside, iron is pretty bad: if you sit in an iron structure on Earth (eg in a ship) you get a slight neutron bath from the cosmic radiation hitting the iron and spalling. The radiation dose goes down (fewer milligrays), but I am quoting everything in effective dose, millisieverts, where neutrons are rated as 20x more damaging to organic matter than ionised particles.

The real problem is that cosmic radiation does not just "pass through and get absorbed by the surface." The ground is made of the same stuff as the regolith shielding, so what is happening in addition to the effect of the iron is that secondary particles are emitted by the floor are bouncing back into the hab.

A polyethylene or water liner will improve this quite significantly. You may have noticed that the Mars X-House and Ice House designs both feature water or polyethylene shielding on the floor of the habitat. This is why.

I may have missed it further back, but how much polyethylene is needed as oppose to water?
Polyethylene can be made in to nicer structural shapes across better temperatures than water can...

They're about the same. PE is slightly better when there is no atmospheric shielding overhead (ie vacuum), water is slightly better when there is atmospheric shielding. Probably due to the neutron dose from cosmic radiation hitting the atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 06/21/2019 08:40 pm
Before we get to the “Amazing” habitats recorded here, we may require some interim shelters. These would be simple structures that could be set up with a minimum of equipment and materials, just Mars pioneer "log cabins" but without the logs.

The sketch below depicts a cylinder partially buried in a trench and covered with regolith. The cylinder could be a large Starship cargo module (8m x 20m) laid horizontally. However, it incorporates a few extra features to enhance its cosmic ray protection and its isolation from cryogenically cold regolith.

To enhance insulation properties it is laid in a trench on small pillars (stones) or beams. The bottom of the cylinder should not touch regolith, so that the only conduction of cold from the ground occurs through the pillars.

The top half is covered by an arc comprised of water ice. Ice blocks may be a preferred because the arc could serve as a compression element to carry its own weight and that of the regolith overburden. The cylinder, being a pressure vessel, would be in tension. The space between the two surfaces would be Mars air which is close to a vacuum and would act like a Thermos bottle.

Regolith would provide the first cosmic ray shield with the water ice layer capturing secondary neutrons before reaching the cylinder.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 06/24/2019 08:57 pm
I can't help but think that the last pages have contained a lot of postings in which people are jumping through hoops to avoid the obvious conclusion: that tunnels really are the optimal interior-space "production method" in the first years of a Mars settlement.

Building surface habs and then piling, what, 2, 3, 5, 8 meters of regolith on top of them to make them radiation-proof? Doesn't it seem like there is a more evident way of making habs with a whole lot of regolith on top?

Also, the huge amounts of imported material (steel, composite, even inflatable rubber accoriding to some) needed for surface habs with the requisite strength to have tons of regolith piled on top... - Well, it just seems like the wrong direction to go for me.

Furthermore, habs dependent on internal pressure for their structural integrity really screams a big no-no to me. Just don't. Way too risky. How would you ever feel at ease in a structure like that?

We shouldn't bring building materials to Mars. We should bring building equipment. And use the materials there (plus the obviously necessary minimum of building materials for interior fittings). In short, don't bring passive, dumb stuff but active, intelligent stuff. Roadheaders, not steel plating.

Carve a big hab out of bedrock and if necessary insulate it with foam or vacuum and perhaps a thin inflatable foil barrier. Would love to hear some more speculation in this - to my ears - more realistic direction.

Sorry for the snotty tone: I just wanted to say this as clearly as possible. I'm normally a quite pleasant conversationalist :-) 
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 06/24/2019 09:02 pm
I agree tunnels are the easiest.

But if you have to have surface hab. I think igloo's are the way to go.
Cast blocks from the water source.
Stack blocks.
Igloo!

Inflatable liner if you want to take off your helmet.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 06/24/2019 09:21 pm
How would the igloos stay put with a pressurized interior and a near-vacuum exterior?
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 06/24/2019 09:41 pm
How would the igloos stay put with a pressurized interior and a near-vacuum exterior?

Small enough igloo or lots of blocks until you have enough weight per volume.

Title: Re: Envisioning Amazing Martian Habitats
Post by: RoboGoofers on 06/24/2019 09:57 pm
[...]

I was familiar with that, and that's exactly what I consider the wrong way around. (Especially that one, it's already on a freakin' trailer, just pull the anchor end from the back of the trailer and tow the whole trailer forward. No dragging. Also, no unhitching.)

You'll notice they only deploy it on very forgiving surfaces.

[Edit: To be fair to them, they are deploying from the side of the trailer, using the length to add width to the panels. However, IMO, adding a pivot on the trailer to turn the spool side-on during deployment would be a better long term solution than dragging the array over the ground and thus always being limited to soft surfaces. Road-width is obviously less of an issue on Mars, so not entirely relevant.]

[Edit 2: "Model 451", am I famous now?]
a self deploying system that doesn't require any dragging or tractoring might have some benefits, such as being able to self stow and in the process self clean. a lightweight rigid chain actuator built into the spool could be used to both push out to deploy and pull in to stow, with passive wheels along the length of the panels to deal with uneven terrain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 06/25/2019 05:19 am
I can't help but think that the last pages have contained a lot of postings in which people are jumping through hoops to avoid the obvious conclusion: that tunnels really are the optimal interior-space "production method" in the first years of a Mars settlement.

Building surface habs and then piling, what, 2, 3, 5, 8 meters of regolith on top of them to make them radiation-proof? Doesn't it seem like there is a more evident way of making habs with a whole lot of regolith on top?
...
...
I believe you may be responding to my post and sketch (reply #2278) immediately before yours.

My assumptions are based on the currently stated SpaceX architecture for Mars. It would entail two cargo ships landing in the first synod and two cargo and two passenger ships in the second synod. In subsequent synods the number of  ships would gradually increase. It is now acknowledged that it may not be feasible to return these ships to Earth until sufficient ISRU propellant and  ground equipment have been established; therefore passenger ships will be retained on Mars as the first habitats.

In addition, Lamontagne and I published two articles that propose large cargo modules to be employed. They would be pressure vessels packed with with equipment and supplies . Once unloaded on Mars, the vessels themselves would become storage tanks for cryogenic liquids, such as propellants produced via ISRU. While we didn’t say so explicitly, they could serve many other purposes. If they were habitats, they would be outfitted  with ECLSS and other built-in equipment on Earth before the trip to Mars. This approach assumes that modules would be separated from ships, which would eventually return to Earth.

Another assumption is that the initial cargo manifests would include standard construction equipment such as loaders and cranes, but not advanced equipment like tunnel boring equipment. These could appear a little later if tunnels become part of the plan. So the simple structure I suggested does not rule out tunnels or any other advanced concept; it is just for the first few landings, before adequate equipment is accumulated. Also, we may find  that the modules contain sufficient GCR protection and insulation so that no additional protection is needed.

Edit: grammar
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 06/25/2019 05:46 am
...
...
We shouldn't bring building materials to Mars. We should bring building equipment. And use the materials there (plus the obviously necessary minimum of building materials for interior fittings). In short, don't bring passive, dumb stuff but active, intelligent stuff. Roadheaders, not steel plating.

Carve a big hab out of bedrock and if necessary insulate it with foam or vacuum and perhaps a thin inflatable foil barrier. Would love to hear some more speculation in this - to my ears - more realistic direction.

Sorry for the snotty tone: I just wanted to say this as clearly as possible. I'm normally a quite pleasant conversationalist :-)
I agree with bringing equipment, but not which equipment to bring in the first few synods. Boring into mars’ surface may not be as easy as we once thought, as discovered by NASA when the recent lander tried to bore into the ground. They expected fairly loose soil but hit hard material almost immediately. If we want easier digging for initial construction we are more likely to find it in on the surface of the  great dunes of Mars, but even here the regolith may have to be broken up. Deeper into the ground will definitely be harder.

The sketch in Reply #2278 is a half-deep trench that could be dug with a automatic pick/hammer and loader. Extracted regolith is piled beside the trench for convenience, so it can be used as cover over the buried cylinder.

Added: we may also want to calculate energy usage rates for tunnel borers and surface loaders.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 06/25/2019 08:13 pm
It is hugely different to send robots or people. A human being would have fixed the penetrator issue in 30 seconds. Human beings are wonderfully versatile and that will definitely come in handy in the early days of a Mars settlement.

A super-strong, mobile, electric, remote-controlled roadheader with human operators and maintenance crew should be able to dig a fantastic cave system if the right place is found. During digging I imagine that it would be operated from the comfort of the Spaceship.

It would of course be modular and share the wheels and chassis with similarly autonomous waste-removal trucks.

I think a TBM is less flexible and would be for a later stage, where the settlement has more resources and would be ready to use a quickly expanding interior space.     
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/26/2019 10:22 am
[...]

I was familiar with that, and that's exactly what I consider the wrong way around. (Especially that one, it's already on a freakin' trailer, just pull the anchor end from the back of the trailer and tow the whole trailer forward. No dragging. Also, no unhitching.)

You'll notice they only deploy it on very forgiving surfaces.

[Edit: To be fair to them, they are deploying from the side of the trailer, using the length to add width to the panels. However, IMO, adding a pivot on the trailer to turn the spool side-on during deployment would be a better long term solution than dragging the array over the ground and thus always being limited to soft surfaces. Road-width is obviously less of an issue on Mars, so not entirely relevant.]

[Edit 2: "Model 451", am I famous now?]
a self deploying system that doesn't require any dragging or tractoring might have some benefits, such as being able to self stow and in the process self clean. a lightweight rigid chain actuator built into the spool could be used to both push out to deploy and pull in to stow, with passive wheels along the length of the panels to deal with uneven terrain.

Doesn't this prove Paul451's point? Easier and lighter to put even active wheels on dusting bots than passive wheels on the entire (huge) solar array. Plus greater risk of panel damage if it redeploys periodically.

Sorry, but I haven't yet seen a proposal more mass efficient than Elon's "party favor" unrolling panels...  :-\
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 06/26/2019 12:29 pm

Sorry, but I haven't yet seen a proposal more mass efficient than Elon's "party favor" unrolling panels...  :-\
Banner-deployed panels dropped from Starship hatches on the equator-facing side of the ship.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 06/26/2019 07:30 pm

Sorry, but I haven't yet seen a proposal more mass efficient than Elon's "party favor" unrolling panels...  :-\
Banner-deployed panels dropped from Starship hatches on the equator-facing side of the ship.

All of the above.
For first deploy do both of the above.

When time permits and power needed for H2O -> CH4 + O2 then do rack mounted panels inclined to south.
Probably space suited person could do this easily.
Could also allow person to adjust angle depending on season.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/26/2019 07:48 pm

Sorry, but I haven't yet seen a proposal more mass efficient than Elon's "party favor" unrolling panels...  :-\
Banner-deployed panels dropped from Starship hatches on the equator-facing side of the ship.

Doesn't scale to the power needed. :(

Vertical panels get less sunlight than horizontal panels. Also to survive the "drop" deployment I think the panel's construction would have to be even heavier than the "party favor," which has much smaller deployment forces.

In fact the maximum scale is so small, is it worth developing at all? I'm inclined to say yes, if only as a quick-to-deploy 'bootstrap' or contingency for early/robotic missions. If there's no ground infrastructure yet, you still need some way to recharge Starship while setting up equipment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/27/2019 01:57 am
Banner-deployed panels dropped from Starship hatches on the equator-facing side of the ship.
Vertical panels get less sunlight than horizontal panels.

Less of an issue on Mars due to the dust.

Also to survive the "drop" deployment I think the panel's construction would have to be even heavier than the "party favor," which has much smaller deployment forces.

I doubt it. To survive unrolling along the ground, the panel has to survive uneven forces, to not tear any weak points. The unpredictability means it will be generally over-engineered compared to the drop-deploy banner. (I mean, you don't have to just drop it, free-fall, self-braking unspooling is a thing.) But the suspension mechanism (the flag-poles) might be proportionately (relative to panel area) heavier than the roller-deployer, since you aren't getting a lot of area per banner but the deployer has to strong enough to be able to support its own deployment out the side of the ship.

(I'm also not a fan of the compressed air "party favor" idea. Inflation-deployment systems have a bad track record in space. Hell, spools have a bad track record.)

is it worth developing at all? I'm inclined to say yes, if only as a quick-to-deploy 'bootstrap' or contingency for early/robotic missions. If there's no ground infrastructure yet, you still need some way to recharge Starship while setting up equipment.

Always the gripping hand.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/27/2019 05:31 am
Banner-deployed panels dropped from Starship hatches on the equator-facing side of the ship.
Vertical panels get less sunlight than horizontal panels.

Less of an issue on Mars due to the dust.

Also to survive the "drop" deployment I think the panel's construction would have to be even heavier than the "party favor," which has much smaller deployment forces.

I doubt it. To survive unrolling along the ground, the panel has to survive uneven forces, to not tear any weak points. The unpredictability means it will be generally over-engineered compared to the drop-deploy banner. (I mean, you don't have to just drop it, free-fall, self-braking unspooling is a thing.) But the suspension mechanism (the flag-poles) might be proportionately (relative to panel area) heavier than the roller-deployer, since you aren't getting a lot of area per banner but the deployer has to strong enough to be able to support its own deployment out the side of the ship.

(I'm also not a fan of the compressed air "party favor" idea. Inflation-deployment systems have a bad track record in space. Hell, spools have a bad track record.)

is it worth developing at all? I'm inclined to say yes, if only as a quick-to-deploy 'bootstrap' or contingency for early/robotic missions. If there's no ground infrastructure yet, you still need some way to recharge Starship while setting up equipment.

Always the gripping hand.
The bottom cargo pods could serve nicely here.
The following seems simple enough. 
Lower pod to the ground
Open door.
Unroll or unfold panels.
Might be done with rigid panels, unfolding and high efficiency cells.  either a pantograph for each pair of panels or some kind of extending boom.
Or the little roller at the front could just move as the panels unfolded slowly two by two,with some kind of mechanism inside the pod.
That being said we are straying from the topic here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/28/2019 05:11 am
Deploy from the top of Starship, but angle down towards the ground. Being high off the ground means the dust will basically always be blown off of it. Same weight advantages of just hanging it, plus you can cover more area.
Title: Re: Envisioning Amazing Martian Habitats
Post by: BZHSpace on 06/28/2019 01:10 pm
Deploy from the top of Starship, but angle down towards the ground. Being high off the ground means the dust will basically always be blown off of it. Same weight advantages of just hanging it, plus you can cover more area.

Dust will be the main issues to the solar panels' efficiency on Mars. The lower solar array on Mars will be useless if the dust come on the panels ... I doubt of the real efficiency of this technology on the long term. Martian habitat wall have to be the way of making energy from the radiations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/29/2019 02:23 am
My main point (which was almost the only thing I wrote, but I decided to throw in the other two minor points for good measure) remains unaddressed -- hanging solar banners off Starship doesn't scale. This is a bunch of R&D work that in the end will only provide <1% of the total PV shipped from Earth. Why?

Banner-deployed panels dropped from Starship hatches on the equator-facing side of the ship.
Vertical panels get less sunlight than horizontal panels.

Less of an issue on Mars due to the dust.

If we're enumerating second-order effects, it's also more of an issue on Mars due to the dust. High tau means more diffuse light, which favors horizontal panels.

Dust accumulation takes time. By that time you'll have plenty of PV deployed to dust off the first panels. If you were only using banner PV that would be different, but a Mars colony needs more power than that.

How much of an effect does angle have on dust? These are extremely tiny dust particles, so I presume Van der waal forces and electrostatic adhesion will be an issue. That can cause clinging to vertical or even inverted surfaces. Surely NASA has done work here.

Worse case scenario for horizontal panels, drive the compressed atmosphere crop panel-duster across the array once a month. A single vehicle with booms on either side could clean many panels at once, and it improves array density because you only need a maintenance road every few lanes.

This all sounds heavy, but remember the necessary solar arrays are going to be huge. You want the panels themselves to be as lightweight as possible.

Also to survive the "drop" deployment I think the panel's construction would have to be even heavier than the "party favor," which has much smaller deployment forces.

I doubt it. To survive unrolling along the ground, the panel has to survive uneven forces, to not tear any weak points. The unpredictability means it will be generally over-engineered compared to the drop-deploy banner. (I mean, you don't have to just drop it, free-fall, self-braking unspooling is a thing.)

While unrolling on the ground it never has to support its own weight while held from one end. The ground supports it all along the panel. Hence lower deployment forces.

Is it easier to lift a big heavy reel of material, or roll it? Obviously rolling, and that reality is reflected in the forces imparted on the reel.


But the suspension mechanism (the flag-poles) might be proportionately (relative to panel area) heavier than the roller-deployer, since you aren't getting a lot of area per banner but the deployer has to strong enough to be able to support its own deployment out the side of the ship.

Bingo. The unrolling PV has "nothing left to take away."


(I'm also not a fan of the compressed air "party favor" idea. Inflation-deployment systems have a bad track record in space. Hell, spools have a bad track record.)


Pathfinder and MER-1 and 2 did fine with an inflation-deployed landing system.

And if the inflation doesn't work or leaks, the panel can still be rolled out manually. The PV panel isn't broken or useless in that case, it just requires more work to deploy. The inflation method is easy to automate though (pick up roll, place roll, inflate, connect power) vs a banner (pick up roll, attach roll to the outside of Starship, trigger unrolling mechanism, erect flagpole, attach free end to flagpole, tension lines, connect power).

is it worth developing at all? I'm inclined to say yes, if only as a quick-to-deploy 'bootstrap' or contingency for early/robotic missions. If there's no ground infrastructure yet, you still need some way to recharge Starship while setting up equipment.

Always the gripping hand.

For those who may be confused: https://en.wikipedia.org/wiki/The_Gripping_Hand

On the contrary, the important "gripping hand" point I was making (which you ignored :P) is the scaling issue. Since banner PV will be never be anything but a marginal producer at best, why bother super optimizing it? Easier to bootstrap by unrolling panels on the ground next to you.

Instead of devoting kilograms to single-task items like specialized support masts ("flagpoles") and self-braking unspooling mechanisms, just use that mass to send more rolls of party favor PV. These are far more useful in the long run.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/29/2019 02:40 am
Deploy from the top of Starship, but angle down towards the ground. Being high off the ground means the dust will basically always be blown off of it. Same weight advantages of just hanging it, plus you can cover more area.

Dust will be the main issues to the solar panels' efficiency on Mars. The lower solar array on Mars will be useless if the dust come on the panels ... I doubt of the real efficiency of this technology on the long term. Martian habitat wall have to be the way of making energy from the radiations.
It won't. If the panels are angled and elevated, dust won't be a problem.

Spirit and Opportunity were relatively low to the ground and had completely horizontal solar panels, basically worst-case for dust collection. Yet still operated for years. Angled and far above the ground will mean clean solar panels. We know this because Opportunity was kept clean of dust when on top of hills but accumulated more dust when in valleys. We're not guessing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 06/29/2019 02:45 am
My main point (which was almost the only thing I wrote, but I decided to throw in the other two minor points for good measure) remains unaddressed -- hanging solar banners off Starship doesn't scale. This is a bunch of R&D work that in the end will only provide <1% of the total PV shipped from Earth. Why?...
...wrong. Hang them at an angle (say 30 degrees or so... so they're out at a radius of about 100 meters all around the vehicle), and they'd provide more than enough power to refuel a Starship.

It might be a dumb idea, but not because it "won't scale".
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/29/2019 03:09 am
My main point (which was almost the only thing I wrote, but I decided to throw in the other two minor points for good measure) remains unaddressed -- hanging solar banners off Starship doesn't scale. This is a bunch of R&D work that in the end will only provide <1% of the total PV shipped from Earth. Why?...
...wrong. Hang them at an angle (say 30 degrees or so... so they're out at a radius of about 100 meters all around the vehicle), and they'd provide more than enough power to refuel a Starship.

It might be a dumb idea, but not because it "won't scale".

You prove my point. Refuel a Starship. One, singular, per synod. But establishing a city on Mars requires many such ships, and more power for colony needs besides.

It would be wildly expensive to dedicate one Starship per installation. Essentially it's using Starship as a staggeringly overpriced mast/tower -- not good economy.

So yeah, it "doesn't scale." Obviously by that I don't mean it's physically impossible to scale, just that other options win economically at that point.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/29/2019 03:29 am
Angled and far above the ground will mean clean solar panels. We know this because Opportunity was kept clean of dust when on top of hills but accumulated more dust when in valleys. We're not guessing.

That is partly guessing. It's guessing that the wind/dust/circulation patterns encountered in a hypothetical extensive Martian PV array farm (with obstacles like PV panels to block/redirect the winds) will be the same as those encountered by a lone Opportunity perched on a hill.

Surely we all realize how a forest can block the wind, yes? Heck wind turbine companies are now using modelling to simulate how turbines effect the local wind (and therefore effect each-other's power output). Given that, we should a priori expect the wind-cleaning power of altitude to be less strong than the Opportunity data suggests.

Perhaps a suitable geometry can be found such that each panel sympathetically assists in cleaning its neighbor, rather than parasitically stealing its wind? Sand dune mimicry?
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 06/29/2019 10:35 am
I always thought of the roll out solar panels as the temporary get power up quickly with no people outside solution. Once you have time panels mounted on frames and tilted to the correct angle are the permanent solution.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/29/2019 06:41 pm
Make your own base tile set!

I've made a number of tiles for a base design system.

Each is 9m to a side, and they can be assembled to build your own base!

Most should be self explanatory, and if there are any tiles you would like to see just let me know!

I'll be glad to send the  sketchup model to anyone who writes to me for it.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 06/29/2019 06:46 pm
I always thought of the roll out solar panels as the temporary get power up quickly with no people outside solution. Once you have time panels mounted on frames and tilted to the correct angle are the permanent solution.
I would have thought they could arrange for Starship to land "facing" south and have designed the ships solar panels to be capable of deployment in Mars gravity. Given these 2 points they would have plenty of power until the main solar array was unloaded.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/29/2019 06:54 pm
I always thought of the roll out solar panels as the temporary get power up quickly with no people outside solution. Once you have time panels mounted on frames and tilted to the correct angle are the permanent solution.
I would have thought they could arrange for Starship to land "facing" south and have designed the ships solar panels to be capable of deployment in Mars gravity. Given these 2 points they would have plenty of power until the main solar array was unloaded.
For some reason, people always think of the first time as the only time.
There is only one ship for whom the solar panels will be a problem.  The first ship on Mars.  For all the others there will be some kind of deployment system and there will be people starting on the second synod.
Just pack a roll out system in one of the base cargo pods, use it once or twice, and that's that.

Starship has to have a sophisticated unloading system it is useless otherwise.

Like the cards?   ;)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/30/2019 07:25 am
I always thought of the roll out solar panels as the temporary get power up quickly with no people outside solution. Once you have time panels mounted on frames and tilted to the correct angle are the permanent solution.

On Earth this makes sense because the PV cells are a lot more expensive per kg than the frames, but on Mars the economics are different. If it's 100% imported mass you're better off cost-wise just unrolling more PV. So imo this is further out than waiting until the colonists "have time" -- this has to wait for ISRU frames.

Probably the easiest and lowest lifecycle cost ISRU frame is simply bulldozing the regolith into parallel angled ridges. No metal or anything needed, just the same lightweight roll of PV.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/30/2019 07:46 am
hanging solar banners off Starship doesn't scale. [...]
but a Mars colony needs more power than that.

First ship. No people, no infrastructure, minimal vehicles, automated operation. Your own words: "If there's no ground infrastructure yet, you still need some way to recharge Starship while setting up equipment."

Even the roll-out unspooling panels I'm assuming are only intended for the earliest operation, not for a colony. Small scale, sub-optimal location, trading ease of deployment for size/efficiency.

How much of an effect does angle have on dust? These are extremely tiny dust particles, so I presume Van der waal forces and electrostatic adhesion will be an issue. That can cause clinging to vertical or even inverted surfaces. Surely NASA has done work here.

Yeah, they landed rovers. The dust got blown off by chance. It clearly can't be that clingy. A vertical banner wouldn't accumulate dust.

Also to survive the "drop" deployment I think the panel's construction would have to be even heavier than the "party favor," which has much smaller deployment forces.
I doubt it. To survive unrolling along the ground, the panel has to survive uneven forces, to not tear any weak points. The unpredictability means it will be generally over-engineered compared to the drop-deploy banner. (I mean, you don't have to just drop it, free-fall, self-braking unspooling is a thing.)
While unrolling on the ground it never has to support its own weight while held from one end. The ground supports it all along the panel. Hence lower deployment forces.

Take a roll of cling-film, hold the end and let it the roll drop to the floor. How many holes in the film between your fingers and the floor? Now take the same spool, make an airtight tube, and try to force it to deploy over sharp uneven gravel while blowing air into it. How many holes now?

Simple tensile strength vs impact/cutting/dragging.

[This is why, if we're going for unrolling on the ground, I'd prefer to deploy from a vehicle, letting the array lay out without putting any pressure on it, rather than either dragging it over the ground or trying to force the spool to unroll using air-pressure from one end. Even then, I think the panel will be thicker/stronger than required for a banner, but not as strong as the party-favour would need to be.]

vs a banner (pick up roll, attach roll to the outside of Starship, trigger unrolling mechanism, erect flagpole, attach free end to flagpole, tension lines, connect power).

Jesus, no. Is anyone actually suggesting that? A pole holding the spool is poked out from the cargo bay at the top of the ship, then lets the panel unroll down the side of the ship. Everything is already connected. You aren't lowering it to the ground as cargo, then picking it up to raise it up again to attach it to the ship, then unspooling it, then attaching extra lines, then plugging it in.

Same with any panel deployed from the lower cargo-hatches (assuming they are still part of the design), you lower the spool, and roll it out, the ship-end is already attached.

The first ships don't go home. I thought that was well established? They bring in the infrastructure so that later ships can be refuelled. They are the first storage tanks, the first power system, the first dwellings even.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 06/30/2019 07:56 am
I always thought of the roll out solar panels as the temporary get power up quickly with no people outside solution.

Yes.

Once you have time panels mounted on frames and tilted to the correct angle are the permanent solution.

You don't need frames. A horizontal wire hung between simple poles could raise a line of panels from the ground to the optimum angle. The bottom of the panels (or a bottom horizontal wire) is pegged to ground at the preferred angle.

(Short poles are a simple ISRU replacement, once that's up and running, until then fairly light to ship. Wire is a little further down the track, but since you need to have power connectors, it shouldn't add a lot of mass to make the power line strong enough to support the panels under Mars-g and low density winds.)

That assumes the dust issue means you really do want them raised up a little. Otherwise you just lay them on the ground. You can grade the ground to the preferred angle as well, if you want. [edit2: Didn't see TM had written this as well.] On the flip-side, if you need to raise them further from the ground -- say the optimum self-dusting height is a metre up -- you can suspend both the top and bottom wires.

(I've been using terms like "panels", "arrays', "film", etc interchangeably. It makes a difference if we need to use thicker cells with rigid backing or thin film, but some of the things we discuss are generic to either.)

[edit: gramma and speln.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Jcc on 06/30/2019 12:56 pm
Make your own base tile set!

I've made a number of tiles for a base design system.

Each is 9m to a side, and they can be assembled to build your own base!

Most should be self explanatory, and if there are any tiles you would like to see just let me know!

I'll be glad to send the  sketchup model to anyone who writes to me for it.

Very cool! Would be great to merge with a Civilization 6 Mars campaign

https://civilization.fandom.com/wiki/Mars_Colony_(Civ6)
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 06/30/2019 04:35 pm

I've added nuclear reactor tiles

One 10 kWe kilopower, with radiator.
One 1 MWe unit.
Radiators for the MWe unit.  Each radiator is 250 kW.  So 12 radiators required for 1 MWe.  I guess as a game you could use a 4:1 ratio of radiators and increase power accordingly.

Each solar tile is 8m x 8m.  So 6 kW peak each, or 64 kWh per day of energy.  For 1 MWe of solar you would need 166 tiles!!  And about twice that to cover the energy value.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 06/30/2019 09:29 pm
ML, hopefully excess calories could be sent to an electrolysis unit, an iron foundry, a polyethylene production plant,  or any process driven by heat. Tiles for that?  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 06/30/2019 09:40 pm
...
...
You don't need frames. A horizontal wire hung between simple poles could raise a line of panels from the ground to the optimum angle. The bottom of the panels (or a bottom horizontal wire) is pegged to ground at the preferred angle.
...
...
You don’t even need wires. Lean them against a row of rocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 06/30/2019 10:15 pm
hanging solar banners off Starship doesn't scale. [...]
but a Mars colony needs more power than that.

First ship. No people, no infrastructure, minimal vehicles, automated operation. Your own words: "If there's no ground infrastructure yet, you still need some way to recharge Starship while setting up equipment."

It seems like the market for this then is... one panel.

Even the roll-out unspooling panels I'm assuming are only intended for the earliest operation, not for a colony. Small scale, sub-optimal location, trading ease of deployment for size/efficiency.

Disagree. Both size and efficiency are unimproved by moving to "better" (ie more complex) systems.

Literally their only disadvantage is solved by unrolling them on angled regolith ridges.

How much of an effect does angle have on dust? These are extremely tiny dust particles, so I presume Van der waal forces and electrostatic adhesion will be an issue. That can cause clinging to vertical or even inverted surfaces. Surely NASA has done work here.

Yeah, they landed rovers. The dust got blown off by chance. It clearly can't be that clingy. A vertical banner wouldn't accumulate dust.

Some of the dust got blown off. But some of it didn't. I don't think we can extrapolate that to say that vertical panels would accumulate zero dust. Hell even on Earth vertical surfaces will gather dust.

Anyway while researching this problem, I came across electrostatics screen technology that can actively remove dust particles using very little power (10 W/m^2 while active, for the ~5 minute cleaning cycle). In lieu of requiring a more expensive mechanical solution, this seems to solve the dust accumulation issue.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120003264.pdf

Also to survive the "drop" deployment I think the panel's construction would have to be even heavier than the "party favor," which has much smaller deployment forces.
I doubt it. To survive unrolling along the ground, the panel has to survive uneven forces, to not tear any weak points. The unpredictability means it will be generally over-engineered compared to the drop-deploy banner. (I mean, you don't have to just drop it, free-fall, self-braking unspooling is a thing.)
While unrolling on the ground it never has to support its own weight while held from one end. The ground supports it all along the panel. Hence lower deployment forces.

Take a roll of cling-film,

Clearly cling film can already support the entire weight of the spool, so this is a non-experiment. A mass optimized solar roll with the extra weight of embedded solar cells and a far longer length is a different load case.

Simple tensile strength vs impact/cutting/dragging.

I don't know how you unroll things, but for me there's no impact, cutting, or dragging involved. Just... rolling. Obviously any large rocks or similar would be avoided (either by simple site selection, or by one pass with the dozer/grader).

[This is why, if we're going for unrolling on the ground, I'd prefer to deploy from a vehicle, letting the array lay out without putting any pressure on it, rather than either dragging it over the ground or trying to force the spool to unroll using air-pressure from one end. Even then, I think the panel will be thicker/stronger than required for a banner, but not as strong as the party-favour would need to be.]

That works too. Not picky.

The main advantage of pneumatic deployment is ease of autonomous deployment. If you have on-Mars teleoperation you can use simple reel trucks, and make the rolls even lighter.

vs a banner (pick up roll, attach roll to the outside of Starship, trigger unrolling mechanism, erect flagpole, attach free end to flagpole, tension lines, connect power).

Jesus, no. Is anyone actually suggesting that? A pole holding the spool is poked out from the cargo bay at the top of the ship, then lets the panel unroll down the side of the ship. Everything is already connected.

So you lose use of a cargo bay door and elevator for every panel you so deploy? That's even worse!

At least with panels unrolled in the ground, you still have full unimpeded access to the Starship, without some boom poking out the door (which now can't close?).

And no, I don't think SpaceX will have made the door larger than necessary so there's "spare room."

The first ships don't go home. I thought that was well established? They bring in the infrastructure so that later ships can be refuelled. They are the first storage tanks, the first power system, the first dwellings even.

If they're dwellings, you probably want (redundant) doors and elevators to access them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 06/30/2019 10:43 pm
hanging solar banners off Starship doesn't scale. [...]
but a Mars colony needs more power than that.

First ship. No people, no infrastructure, minimal vehicles, automated operation. Your own words: "If there's no ground infrastructure yet, you still need some way to recharge Starship while setting up equipment."

Even the roll-out unspooling panels I'm assuming are only intended for the earliest operation, not for a colony. Small scale, sub-optimal location, trading ease of deployment for size/efficiency.

Again, I see no "ease of deployment" advantage over unrolling horizontal panels right next to the Starship.

How much of an effect does angle have on dust? These are extremely tiny dust particles, so I presume Van der waal forces and electrostatic adhesion will be an issue. That can cause clinging to vertical or even inverted surfaces. Surely NASA has done work here.

Yeah, they landed rovers. The dust got blown off by chance. It clearly can't be that clingy. A vertical banner wouldn't accumulate dust.

Some of the dust got blown off. But some of it didn't. I don't think we can extrapolate that to say that vertical panels would accumulate zero dust. Hell even on Earth vertical surfaces will gather dust.

Anyway while researching this problem, I came across electrostatics screen technology that can actively remove dust particles using very little power (10 W/m^2 while active, for the ~5 minute cleaning cycle). Rather than requiring a more expensive solution, this seems to solve the dust accumulation issue.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120003264.pdf

Also to survive the "drop" deployment I think the panel's construction would have to be even heavier than the "party favor," which has much smaller deployment forces.
I doubt it. To survive unrolling along the ground, the panel has to survive uneven forces, to not tear any weak points. The unpredictability means it will be generally over-engineered compared to the drop-deploy banner. (I mean, you don't have to just drop it, free-fall, self-braking unspooling is a thing.)
While unrolling on the ground it never has to support its own weight while held from one end. The ground supports it all along the panel. Hence lower deployment forces.

Take a roll of cling-film,

Clearly cling film can already support the entire weight of the spool, so this is a non-experiment. A mass optimized solar roll with the extra weight of embedded solar cells and a far longer length is a different load case.

Simple tensile strength vs impact/cutting/dragging.

I don't know how you unroll things, but for me there's no impact, cutting, or dragging involved. Just... rolling. Obviously any large rocks or similar would be avoided (either by simple site selection, or by one pass with the dozer/grader).

[This is why, if we're going for unrolling on the ground, I'd prefer to deploy from a vehicle, letting the array lay out without putting any pressure on it, rather than either dragging it over the ground or trying to force the spool to unroll using air-pressure from one end. Even then, I think the panel will be thicker/stronger than required for a banner, but not as strong as the party-favour would need to be.]

That works too. Not picky.

The main advantage of pneumatic deployment is ease of autonomous deployment. If you have on-Mars teleoperation you can use simple reel trucks, and make the rolls even lighter.

vs a banner (pick up roll, attach roll to the outside of Starship, trigger unrolling mechanism, erect flagpole, attach free end to flagpole, tension lines, connect power).

Jesus, no. Is anyone actually suggesting that? A pole holding the spool is poked out from the cargo bay at the top of the ship, then lets the panel unroll down the side of the ship. Everything is already connected.

So you lose use of a cargo bay door and elevator for every panel you so deploy? That's even worse!

At least with panels unrolled in the ground, you still have full unimpeded access to the Starship, without some boom poking out the door (which now can't close?).

And no, I don't think SpaceX will have made the door larger than necessary so there's "spare room."

Why is that worse? You only need 1 door, and the design has 2. Even so, the "elevator" (actually a crane) should be able to function fine, if you dont mind it partially obscuring the panel while in operation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/01/2019 02:06 am
ML, hopefully excess calories could be sent to an electrolysis unit, an iron foundry, a polyethylene production plant,  or any process driven by heat. Tiles for that?  :)
Yes, here are the process modules tiles.  The processes are in hidden in the modules, so they can be pretty much anything :-)
The waste heat from the nuclear reactor is pretty low grade, suitable for melting water or heating habitats but not much else.
So I expect there will be some more heat rejection units at the process plants.
There is also an atmospheric processing plant,  extracting water, CO2 and nitrogen from the atmosphere.
White lines are pipe lines, yellow lines are power lines.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/01/2019 07:15 am
As Mark_Twain points out, electrostatic cleaning tech will handle the solar panel cleaning. Dust accumulation should be a maintenance issue; at the very least there will be rovers trundling around and all one of them needs to do is pick up a feather duster from WalMart in its robotic arm. Or burp some gas from the engines or the RCS.

To add to what Paul451 says about roll-outs being torn and damaged, flat panels are also less likely to be damaged by rocket engine sandblasting from subsequent landings, or ripped up and sent flying from a landing that gets too close.

But this is more a topic for the Power Options for A Martian Settlement thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/01/2019 05:35 pm
Two lay down and general exterior storage areas, with permanent Starships.

Calcium carbonate storage(for concrete)
Iron Ore storage (for steel)
Silica sand storage (for glass)

That about all the modules I can think of.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/01/2019 05:39 pm
Forgotten these : Hospital (infirmary) and labs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/01/2019 06:32 pm
Phase 1 and phase 2, Mars base.
Phase 1 has 2 cargo ships, a number of rovers, a garage and a water mine.  A number of scientific and production automated experiments.

Phase 2 has 4 cargo ships and 2 passenger ships.  Solar arrays, (about 2 MWe ) to produce the propellant for the return of two ships, a back up nuclear power unit, a number of production units for electrolysis and Sabatier, some demonstration units for production and a few new mines.  Food production is partial, with experimental greenhouses, vat grown protein and carbohydrates.

Although obviously symbolic, everything is more or less to scale.

If anyone wants to set things up differently, I can send the tiles :-)  There are free versions of sketchup.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 07/03/2019 06:33 pm
Phase 1 and phase 2, Mars base.
Phase 1 has 2 cargo ships, a number of rovers, a garage and a water mine.  A number of scientific and production automated experiments.

Phase 2 has 4 cargo ships and 2 passenger ships.  Solar arrays, (about 2 MWe ) to produce the propellant for the return of two ships, a back up nuclear power unit, a number of production units for electrolysis and Sabatier, some demonstration units for production and a few new mines.  Food production is partial, with experimental greenhouses, vat grown protein and carbohydrates.

Although obviously symbolic, everything is more or less to scale.

If anyone wants to set things up differently, I can send the tiles :-)  There are free versions of sketchup.
Is there a possibility to add engineering metadata values that can be just simply summed up?
Metadata values like volume, power generation/consumption, heat generation/ radiated, mass shipping from Earth/isru etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 07/03/2019 07:11 pm
Phase 1 and phase 2, Mars base.
Phase 1 has 2 cargo ships, a number of rovers, a garage and a water mine.  A number of scientific and production automated experiments.

Phase 2 has 4 cargo ships and 2 passenger ships.  Solar arrays, (about 2 MWe ) to produce the propellant for the return of two ships, a back up nuclear power unit, a number of production units for electrolysis and Sabatier, some demonstration units for production and a few new mines.  Food production is partial, with experimental greenhouses, vat grown protein and carbohydrates.

Although obviously symbolic, everything is more or less to scale.

If anyone wants to set things up differently, I can send the tiles :-)  There are free versions of sketchup.
Suggestions:
... A legend for the tile impaired.
... Ship-landing square pad with SpX symbol should be off to one side and at a lower level like Boca Chica. Maybe in a crater, for protection from flying debris.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/03/2019 11:52 pm
Phase 1 and phase 2, Mars base.
Phase 1 has 2 cargo ships, a number of rovers, a garage and a water mine.  A number of scientific and production automated experiments.

Phase 2 has 4 cargo ships and 2 passenger ships.  Solar arrays, (about 2 MWe ) to produce the propellant for the return of two ships, a back up nuclear power unit, a number of production units for electrolysis and Sabatier, some demonstration units for production and a few new mines.  Food production is partial, with experimental greenhouses, vat grown protein and carbohydrates.

Although obviously symbolic, everything is more or less to scale.

If anyone wants to set things up differently, I can send the tiles :-)  There are free versions of sketchup.
Suggestions:
... A legend for the tile impaired.
... Ship-landing square pad with SpX symbol should be off to one side and at a lower level like Boca Chica. Maybe in a crater, for protection from flying debris.
I'm hopping to add hotspots to a MArspedia page, waiting for the Forum administrator to activate the function.
Here is a summary of the tiles:
https://marspedia.org/Settlement_facilities

And the main page of these tiles:
https://marspedia.org/Create_a_settlement

I guess I could create a playing board, have a crater and let the player decide where he wants the Spaceport?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2019 01:58 am
Phase 1 and phase 2, Mars base.
Phase 1 has 2 cargo ships, a number of rovers, a garage and a water mine.  A number of scientific and production automated experiments.

Phase 2 has 4 cargo ships and 2 passenger ships.  Solar arrays, (about 2 MWe ) to produce the propellant for the return of two ships, a back up nuclear power unit, a number of production units for electrolysis and Sabatier, some demonstration units for production and a few new mines.  Food production is partial, with experimental greenhouses, vat grown protein and carbohydrates.

Although obviously symbolic, everything is more or less to scale.

If anyone wants to set things up differently, I can send the tiles :-)  There are free versions of sketchup.
Is there a possibility to add engineering metadata values that can be just simply summed up?
Metadata values like volume, power generation/consumption, heat generation/ radiated, mass shipping from Earth/isru etc.
Good idea, i've added some data to the following page :
https://marspedia.org/Create_a_settlement
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/13/2019 03:30 am
So I talked about the idea of a game with my son, and this is what we made up together on Tabletop simulator, on Steam.
It's just a mock-up, scoring would require actual programming, but still its fun to see :-)

I've also joined a spreadsheet that has most of the tile characteristics.  Just change the number of tiles in the correct column, and presto, a Mars base!

Would love to have comments on the tiles and the spreadsheet if anyone finds the time.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 07/13/2019 10:32 am
Sorry, can’t read fine print.

I'ts an amusing game to me,  :) but my grandkids are accustomed to a lot of action. :P
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/13/2019 06:03 pm
Sorry, can’t read fine print.

I'ts an amusing game to me,  :) but my grandkids are accustomed to a lot of action. :P
If you click on the image it gets quite large.
No game is good for everyone  :-) 

But if you played this one, what would you expect it to have?  For one, I think I will be adding a wind turbine tile.  I will also add power storage to the power tile.

And I need to find a way to differentiate between a module that comes from Earth and one that is built from in situ materials.  One of the things this set of tiles shows me is that using local materials for construction is very advantageous, Not so much in terms of cost, but in terms of a limited mass budget from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: wes_wilson on 07/13/2019 06:24 pm
Sorry, can’t read fine print.

I'ts an amusing game to me,  :) but my grandkids are accustomed to a lot of action. :P
[...]
But if you played this one, what would you expect it to have? 
[...]

Angry Martians resisting the Earthling invasion?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/13/2019 07:13 pm
Sorry, can’t read fine print.

I'ts an amusing game to me,  :) but my grandkids are accustomed to a lot of action. :P
[...]
But if you played this one, what would you expect it to have? 
[...]


Angry Martians resisting the Earthling invasion?

Well we could have a transdimensional portal and evil aliens.  I believe it's called DOOM and had some measure of success in the past :-)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Barney on 07/13/2019 08:31 pm
A mars colony will need all the power it can have, melting ice for the water then distilling same calls for heating
it til it boils off into steam, taking that a little further to produce more steam to run a generator seems like some-
thing that is a possibility, giving the colonists another source of power.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 07/13/2019 10:07 pm
A mars colony will need all the power it can have, melting ice for the water then distilling same calls for heating
it til it boils off into steam, taking that a little further to produce more steam to run a generator seems like some-
thing that is a possibility, giving the colonists another source of power.
At Mars pressures water will boil at relatively low temperatures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 07/13/2019 11:46 pm
A mars colony will need all the power it can have, melting ice for the water then distilling same calls for heating
it til it boils off into steam, taking that a little further to produce more steam to run a generator seems like some-
thing that is a possibility, giving the colonists another source of power.
At Mars pressures water will boil at relatively low temperatures.

You save on not having to heat the water up to boiling, but the energy needed to actually vaporise water is the same whether it's in a vacuum or under pressure. Since the energy comes from the rest of the water, if that water isn't being heated, then the it will quickly freeze. So in order to use vacuum to distil water, you need to supply the same amount of heat to keep the water from freezing as you would on Earth to keep it boiling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 07/14/2019 08:47 am
A mars colony will need all the power it can have, melting ice for the water then distilling same calls for heating
it til it boils off into steam, taking that a little further to produce more steam to run a generator seems like some-
thing that is a possibility, giving the colonists another source of power.
At Mars pressures water will boil at relatively low temperatures.

You save on not having to heat the water up to boiling, but the energy needed to actually vaporise water is the same whether it's in a vacuum or under pressure. Since the energy comes from the rest of the water, if that water isn't being heated, then the it will quickly freeze. So in order to use vacuum to distil water, you need to supply the same amount of heat to keep the water from freezing as you would on Earth to keep it boiling.
Yes true. The point I was trying to make was that the low pressure low temperature steam that is generated would not be useful for power generation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/16/2019 10:18 am
Turns out I mixed up the models for 1-D and 2-D (more accurate) transport. 2-D modeling shows worse results for thin shielding because it includes secondaries and neutron back transportation, but better for thick shielding as it is scattered within the bulk of the material. 1-D transport just treated each fragmentation as a shotgun blast.

Even with iron-rech Gusev regolith, you only need 200g/cm2 to get the start of shielding benefits, which is 60cm of Martian basalt or 130cm of Martian regolith. At 400g/cm2 you are cutting surface radiation by 5/6ths, which is 2.6m of Martian regolith or 130cm of basalt.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ice on 07/17/2019 01:51 pm
HD resolution versions for SpaceX's renders of Starship at Mars Base Alpha and on the Moon from Paul Wooster's presentation: https://www.humanmars.net/2019/07/hd-quality-official-renders-of-spacex.html (https://www.humanmars.net/2019/07/hd-quality-official-renders-of-spacex.html)

https://twitter.com/human_Mars/status/1151488077925425152

Quote
In April @ElonMusk teased 2 new low resolution renders with @SpaceX's #Starship on the Moon and at Mars Base Alpha. Now we have HD resolution versions of those renders from Paul Wooster's presentation at #Humans2Mars summit 2019 organized by @ExploreMars:
https://www.humanmars.net/2019/07/hd-quality-official-renders-of-spacex.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/21/2019 04:03 am
Early base inflatable habitat with regolith cover.

Inflatable for tight packaging, internal structure for support in case of accident, regolith cover.

2 full floors and one technical floor.

This is mostly for sleeping and personal/activity space.  At the back of the image is an open garage.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 07/21/2019 03:05 pm
A mars colony will need all the power it can have, melting ice for the water then distilling same calls for heating
it til it boils off into steam, taking that a little further to produce more steam to run a generator seems like some-
thing that is a possibility, giving the colonists another source of power.
If you are using electrical power - to power a process - to generate power, it is essentially NOT another source of power. Due to inefficiencies it will be a guaranteed waste of energy.

If there was some other benefit like time-shift or storage from day to night, or normal to sandstorm that might be useful, but your idea doesn't offer that.

Edit: It would be a perpetual motion machine, if it could even power itself...!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/23/2019 02:50 am
View of the inflatable habitat interior.  Faux finish wood seems like a good idea, somehow.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/23/2019 02:50 pm
View of the inflatable habitat interior.  Faux finish wood seems like a good idea, somehow.


Just needs some shag rugs, some of that ugly orange plastic and a lava lamp or two and it's totally 70s!

As for lighting, reading up a bit on the Coelux lighting panels, you could probably use fibre optics from tracking concentrators to illuminate the sky panels and make a fake "balcony" like you have there in #2. It's not like there are a lot of clouds or anything on Mars so the sky bit will be pretty constant; you could tune it to be Earthlike if you want.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/24/2019 12:30 am
Changed the color scheme to something a bit more contemporary and added plants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/25/2019 01:14 am
A well equipment mineralogy and process lab, plus a biological lab on the upper floor.
Not certain these two uses really mix, but whatever.  Got to keep everything clean anyway.

Built into the same expandable module as the earlier living quarters.  Most of the equipment is downloaded from the Sketchup 3D warehouse.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/25/2019 02:14 am
If creating systems that can operate at Mars pressure proves too difficult, or if maintenance is required frequently, the main production equipment for the propellant production of two Starships would fit into a pressurized module with the same dimensions as the previous ones.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/27/2019 02:50 am
Multilayer plastic dome, basically a short transparent Bigelow module.
Built on Earth, expanded on the surface.

For meetings, gatherings and probably lunch.

Don't spend more than one or two hours a day there.

Off limits during solar flares :-)
Chilly in the evenings...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/27/2019 04:14 pm
A few more views of the mushroom.

Would transparent plastic really be tough enough?  There is a paper on this, but seems a bit out there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/27/2019 04:50 pm
A few more views of the mushroom.

Would transparent plastic really be tough enough?  There is a paper on this, but seems a bit out there.

I think yes, but it would need reinforcement bands horizontally too, not just the vertical hoops shown. Currently the transparent plastic is taking all the horizontal pressure loads.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/27/2019 07:03 pm
So if plastic works, I guess this works as well.

Greenhouse, open for the day, closed with reflective insulated curtains at night.

This would be an experimental greenhouse, built at the second synod, to experiment with the best mixture of natural and artificial light, and to produce some fresh food for variety.  Coupled with a biological and botanical lab.  Again, colonists would try to not spend entire days in there, as radiation protection is minimal.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 07/27/2019 07:20 pm
Nice, but plants have internal pressure as do humans, so both require a certain amount of external pressure. i.e. may not survive Mars' low air pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/27/2019 08:36 pm
Nice, but plants have internal pressure as do humans, so both require a certain amount of external pressure. i.e. may not survive Mars' low air pressure.
Need to improve my pictures!
There is a heavy plastic wall all around.  The greenhouse is at Earth pressure.  Think i'll add some stiffeners to make this more apparent.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/27/2019 09:20 pm
Interior with stiffeners, to reduce the strain on the plastic.

Also added 12 x 500W LED lights, to help those tomatoes to grow!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/28/2019 01:06 am
Interior with stiffeners, to reduce the strain on the plastic.

Also added 12 x 500W LED lights, to help those tomatoes to grow!

Again, why only stiffeners in one direction? That limits you to thick plastic that can take ~all load in the other direction. If you had reinforcement on 2-3 axes (90 degree orthogrid or 60 degree isogrid) it would allow much thinner plastic to be used.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/28/2019 06:46 pm
Interior with stiffeners, to reduce the strain on the plastic.

Also added 12 x 500W LED lights, to help those tomatoes to grow!

Again, why only stiffeners in one direction? That limits you to thick plastic that can take ~all load in the other direction. If you had reinforcement on 2-3 axes (90 degree orthogrid or 60 degree isogrid) it would allow much thinner plastic to be used.

Because once I've loaded the plants into the model it has too many polygons and is almost impossible to work with ;-)
I agree that the solution is divide and conquer, just as for glass.  Not yet had the guts to work out the strain though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Diagoras on 07/28/2019 06:48 pm
I've been dipping in and out of this thread for a while, and every time I do I feel like I learn something new. So thanks to all the experts and amateurs for chiming in.

I wonder if they could do something else for me though - anyone willing and able to summarize the main takeaways about Martian habitats? There's some I've managed to extract myself (the planet provides a whole lot of radiation shielding, the atmosphere isn't bad at it either at lower altitudes, raising the horizon can buy you a lot of radiation shielding, etc.) but I figure someone who has been an active participant might be best placed to distill the top ten points we've managed to settle on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/28/2019 07:48 pm
I've been dipping in and out of this thread for a while, and every time I do I feel like I learn something new. So thanks to all the experts and amateurs for chiming in.

I wonder if they could do something else for me though - anyone willing and able to summarize the main takeaways about Martian habitats? There's some I've managed to extract myself (the planet provides a whole lot of radiation shielding, the atmosphere isn't bad at it either at lower altitudes, raising the horizon can buy you a lot of radiation shielding, etc.) but I figure someone who has been an active participant might be best placed to distill the top ten points we've managed to settle on.
My personal take:
1- A purely solar Mars colony is possible.  The solution to the darkest dust storms (Opportunity killers) is overbuilding the solar farm to produce excess propellant storage, and burn the excess during the dark times.  For the rest of the storm, reduce propellant production.  Solar still has some output during storms.
2- A nuclear solution would be simpler.
3- Locally produced food is going to require extensive resources.  At the beginning, better bring the food from Earth.  There are too many unknowns, and the technology is progressing fast on Earth.  But by all means include a good lab in the first human mission.
4- There is a lot of water about.  A colony will produce a lot of excess heat, and melting the water will use just a small portion of this.  There is a lot of appeal to using water ice as a building material, but I, personally, have not been convinced yet. 
5- Electrolysis of water to produce return propellant for the ships is the main energy using process of the colony.  About 90% of the energy use goes to that single process. 
6- Radiation damage is cumulative.  You can create some spaces in the colony that are poorly protected, just as long as you spend most of you time in well protected spaces. So windows are OK, but probably not in the room you sleep in.
7- Designing for 1 atmosphere pressure is possible, and the gain from reducing pressure is unknown but possibly nil.  Producing the return propellant also produces enough oxygen and nitrogen for the colony.
8- A Mars colony is not a colossal endeavour at the scale of the Earth economy.  Previous numbers were wildly inflated due to transportation costs, an expensive, super optimised design process and because the Earth economy itself has grown tremendously, reducing the pro rata cost.
9- Building underground is cheaper.  The advantages of natural lighting are marginal, but might be psychologically essential.  Artificial light has progressed tremendously and may be up to the task of adequately simulating the Sun.
10- Large domes are really expensive and don't make much sense.  But they have a lot of appeal and can be build if the will is there.
11- In-situ glass is possible, but don't plan on large windows for quite some time.  Small glass panes in metal frames would work.
12- Mars building are mostly tension structures.  Earth buildings are mostly compression structures.  This fundamentally changes designs from Earth to Mars, but further work is needed.
13-  Steel will be produced in-situ sooner than later.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/28/2019 09:39 pm
I've been dipping in and out of this thread for a while, and every time I do I feel like I learn something new. So thanks to all the experts and amateurs for chiming in.

I wonder if they could do something else for me though - anyone willing and able to summarize the main takeaways about Martian habitats? There's some I've managed to extract myself (the planet provides a whole lot of radiation shielding, the atmosphere isn't bad at it either at lower altitudes, raising the horizon can buy you a lot of radiation shielding, etc.) but I figure someone who has been an active participant might be best placed to distill the top ten points we've managed to settle on.
My personal take:
1- A purely solar Mars colony is possible.  The solution to the darkest dust storms (Opportunity killers) is overbuilding the solar farm to produce excess propellant storage, and burn the excess during the dark times.  For the rest of the storm, reduce propellant production.  Solar still has some output during storms.
2- A nuclear solution would be simpler.
3- Locally produced food is going to require extensive resources.  At the beginning, better bring the food from Earth.  There are too many unknowns, and the technology is progressing fast on Earth.  But by all means include a good lab in the first human mission.
4- There is a lot of water about.  A colony will produce a lot of excess heat, and melting the water will use just a small portion of this.  There is a lot of appeal to using water ice as a building material, but I, personally, have not been convinced yet. 
5- Electrolysis of water to produce return propellant for the ships is the main energy using process of the colony.  About 90% of the energy use goes to that single process. 
6- Radiation damage is cumulative.  You can create some spaces in the colony that are poorly protected, just as long as you spend most of you time in well protected spaces. So windows are OK, but probably not in the room you sleep in.
7- Designing for 1 atmosphere pressure is possible, and the gain from reducing pressure is unknown but possibly nil.  Producing the return propellant also produces enough oxygen and nitrogen for the colony.
8- A Mars colony is not a colossal endeavour at the scale of the Earth economy.  Previous numbers were wildly inflated due to transportation costs, an expensive, super optimised design process and because the Earth economy itself has grown tremendously, reducing the pro rata cost.
9- Building underground is cheaper.  The advantages of natural lighting are marginal, but might be psychologically essential.  Artificial light has progressed tremendously and may be up to the task of adequately simulating the Sun.
10- Large domes are really expensive and don't make much sense.  But they have a lot of appeal and can be build if the will is there.
11- In-situ glass is possible, but don't plan on large windows for quite some time.  Small glass panes in metal frames would work.
12- Mars building are mostly tension structures.  Earth buildings are mostly compression structures.  This fundamentally changes designs from Earth to Mars, but further work is needed.
13-  Steel will be produced in-situ sooner than later.

One issue we found with Solar power while doing the Mars Society competition is the weight of connectors. Copper isn't found everywhere on Mars, and electrical conntectors are heavy...and there is basically no good subsititue for Copper right now. The mass for importing 100MW of Solar that was redundant enough vs. a nuclear option was actually worse by about 20% and then you still needed storage to last for up to 4-5 months in some cases.
Plus nuclear has alot of waste heat that can be used for heating the colony meaning you can skimp on insulation, although the heat isn't very usable to melting ice. You don't need much power for that as long as it is a continuous process though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/28/2019 10:11 pm
As I said in point 2.  Nuclear would be simpler.  But it is not a showstopper to not have nuclear.

About connectors do you mean the actual point of connection or the wiring between the panels?  Because the wiring could be aluminium, that can easily compensate being 30% less conductive by being three times lighter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 07/29/2019 03:26 am
I agree that the solution is divide and conquer, just as for glass.  Not yet had the guts to work out the strain though.

As a mental model of an Earthly analogy, for 1atm, picture a floor of a 10m (33ft) deep swimming pool as wide a span as the structure you are building, suspended over your head, supported only at the edges. Or anything supporting ten tonnes per metre span.

For 1/5th atm, pure oxygen, picture the elevated floor of a 2m (7ft) deep pool, as wide as your structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/29/2019 08:50 am
I've been dipping in and out of this thread for a while, and every time I do I feel like I learn something new. So thanks to all the experts and amateurs for chiming in.

I wonder if they could do something else for me though - anyone willing and able to summarize the main takeaways about Martian habitats? There's some I've managed to extract myself (the planet provides a whole lot of radiation shielding, the atmosphere isn't bad at it either at lower altitudes, raising the horizon can buy you a lot of radiation shielding, etc.) but I figure someone who has been an active participant might be best placed to distill the top ten points we've managed to settle on.

Compared to free space, Mars atmosphere and the bulk of the planet cuts cosmic radiation by a third. Half is blocked by the planet, and the remaining radiation is cut by a third. Unfortunately, it gets harder to reduce the radiation dose further because the initial shielding is "free." Most radiation on Mars is from light secondary particles generated by hitting the atmosphere.

Regolith aka dirt is a cheap shield, but it either needs to be quite thin (a couple of cm) or quite thick (1.5m+). This is due to the Pfotzer Maximum, where neutrons from cosmic ray collisions increase quite drastically. About 5m of it (about 7 tonnes per square metre) is enough to drop radiation to near-Earth levels.

Water ice is the best, although several metres of it are needed to cut the radiation down to near-Earth levels. It can be made entirely bubble-free and transparent. There is also no Pfotzer Maximum as any neutrons generated are quickly absorbed by the hydrogens. Ice can be as thin or as thick as you want and still provide shielding.

Mixing layers of ice and regolith achieves a very high degree of shielding without the need to use so much water.

When we talk about "metres/tonnes of shielding," the minimum amount is always assumed to be the minimum amount needed to shield a dome. In practice, cylinders and other non-spherical structures will provide greater thicknesses of shielding simply due to the incoming particals travelling through slanted shielding. Even in a dome, standing away from the centre reduces the dose.

Small windows have virtually no radiation penalty. For example, the monitor you are probably reading this on likely takes up (50 horizontal x 25 degrees vertical) no more than 0.3% of the spherical area around you. Looking out on a Martian horizon, that's only 0.3% of the radiation flux... coming through about 200g/cm2 of atmospheric radiation shielding. Sitting next to it for 24 hours a day will only give a radiation dose of 0.3mSv, which is small compared to the annual background radiation dose on Earth of about 5mSv/year and a tiny fraction of the 240mSv over a year on Mars without shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/29/2019 09:11 am
I agree that the solution is divide and conquer, just as for glass.  Not yet had the guts to work out the strain though.

As a mental model of an Earthly analogy, for 1atm, picture a floor of a 10m (33ft) deep swimming pool as wide a span as the structure you are building, suspended over your head, supported only at the edges. Or anything supporting ten tonnes per metre span.

For 1/5th atm, pure oxygen, picture the elevated floor of a 2m (7ft) deep pool, as wide as your structure.

Hoop stress is:
(internal pressure x radius) / thickness

Add in the safety factor you want.

That's it. Decrease the radius with lobed structures and you can make the walls as thin as you like (within reason) so long as the rest of the vessel has the rigging to handle the redistributed pressure. NASA docs are your friend.

http://articles.adsabs.harvard.edu//full/2005ESASP.581E.101L/0000101.001.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/29/2019 10:15 am
I agree that the solution is divide and conquer, just as for glass.  Not yet had the guts to work out the strain though.

As a mental model of an Earthly analogy, for 1atm, picture a floor of a 10m (33ft) deep swimming pool as wide a span as the structure you are building, suspended over your head, supported only at the edges. Or anything supporting ten tonnes per metre span.

For 1/5th atm, pure oxygen, picture the elevated floor of a 2m (7ft) deep pool, as wide as your structure.

Hoop stress is:
(internal pressure x radius) / thickness

Add in the safety factor you want.

That's it.

For an isotopic material (eg steel or glass), that's it. But for carbon fiber or inflatables you need to know the axial stress too, which is 1/2 the hoop stress.

For an inflatable greenhouse, it would "just" have straight reinforcing lines at half the spacing of the hoop reinforcements. Perhaps not too many polygons?

Bigelow/TransHab modules used exactly that layout, a grid with twice as many hoop straps as axial straps. COPVs are more often wound at an angle of atan(2) ~= 63.4°, yielding the same result.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/29/2019 01:35 pm
Thank you to all that wrote or sent references.
From two slightly aged papers and the hoop stress equations, it would appear that a lobed structure of polyethylene, with lobes 1m wide or smaller and reinforced with fibers at the lobe junctions and longitudinal fibers would be OK.  Probably two or more layers of 1mm poly.  About 3 kg/m2 for full Earth pressure.
Light transmittance would be about 50%.  Some form of removable multi-layer insulation would be required to reduce night time heat losses.  Some supplementary artificial lighting would help keep the mass down and increase productivity.

It's not a gigantic gain compared to a totally artificially lit greenhouse.  It is better than an entirely natural greenhouse.  One of the experiments worth conducting would be to set up a number of small greenhouses with different pressures to see what could be optimized for  surface growth.

My original impression remains that a tunnel construction with in-situ materials and artificial lighting would probably be much cheaper and reliable than this.  So I see it as a kind of experimental station, that would be replaced by tunnels as soon as these can be made, unless there are interesting new discoveries made about naturally lit greenhouses.

However, building a lobbed structure  for spectacular viewing of the countryside in a more or less spherical structure would be possible, 50% loss of transmittance is probably not that perceptible.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/29/2019 02:47 pm
Thank you to all that wrote or sent references.
From two slightly aged papers and the hoop stress equations, it would appear that a lobed structure of polyethylene, with lobes 1m wide or smaller and reinforced with fibers at the lobe junctions and longitudinal fibers would be OK.  Probably two or more layers of 1mm poly.  About 3 kg/m2 for full Earth pressure.
Light transmittance would be about 50%.  Some form of removable multi-layer insulation would be required to reduce night time heat losses.  Some supplementary artificial lighting would help keep the mass down and increase productivity.

It's not a gigantic gain compared to a totally artificially lit greenhouse.  It is better than an entirely natural greenhouse.  One of the experiments worth conducting would be to set up a number of small greenhouses with different pressures to see what could be optimized for  surface growth.

My original impression remains that a tunnel construction with in-situ materials and artificial lighting would probably be much cheaper and reliable than this.  So I see it as a kind of experimental station, that would be replaced by tunnels as soon as these can be made, unless there are interesting new discoveries made about naturally lit greenhouses.

However, building a lobbed structure  for spectacular viewing of the countryside in a more or less spherical structure would be possible, 50% loss of transmittance is probably not that perceptible.


Transparent greenhouses are pretty miserable at retaining heat, but greenhouses in vacuum tend to run very heat from all the waste heat. It might work out that having a transparent greenhouse during the day with minimal lights will stay cool during the night when the lights are turned up. The heat is a problem even for small modules, and would only get worse for larger ones.

Plants have proven to be a big morale boost in space, and having them in sight on the surface (as seen from other windowed modules) would no doubt be beneficial.
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 07/29/2019 03:42 pm
Thank you to all that wrote or sent references.
From two slightly aged papers and the hoop stress equations, it would appear that a lobed structure of polyethylene, with lobes 1m wide or smaller and reinforced with fibers at the lobe junctions and longitudinal fibers would be OK.  Probably two or more layers of 1mm poly.  About 3 kg/m2 for full Earth pressure.
Light transmittance would be about 50%.  Some form of removable multi-layer insulation would be required to reduce night time heat losses.  Some supplementary artificial lighting would help keep the mass down and increase productivity.
Worth bearing in mind that to a 0th order of magnitude, the solar spectrum as emitted by the sun provides ~96lm/W.
The ~1050W/m^2 of light at the earths surface peak if you  feed it through a 20% efficient solar panel however, you get 210W.
With 10% loss electrical path,  and the most efficient LEDs, you need ~600W to produce equivalent amount of light per m^2.

So, the 'transmissivity' of PV-LED can be ~30%, not 20%.

This is as significant smount of solar energy comes in more infrared than is usable by either plant or eye.

Unfortunately, the sources I find on wikipedia and otherwise do not do the proper calculation, so I can't quite find the accurate number.
They for example integrate over a nominal truncated 5800K spectrum instead of the solar spectrum at the surface of earth to compute lm/W.

I am looking for relevant data to do this better.


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/30/2019 01:57 am
I have re arranged the habitat so it looks less like a motel and more like a house hybridized with a meccano set.
Hope it feel more comfortable!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/30/2019 12:36 pm
For your transparent inflatables, you'd want ETFE or polyvinyl fluoride (Tedlar). ETFE has a transmissivity of 75% through 0.2mm, 0.3mm and 0.2mm.

Polyethylene has a lower transmissivity, especially for blue and red wavelengths which are also the most photosynthetically useful. It also weakens and darkens fairly quickly, whereas ETFE lasts for decades. ECFTE is even stronger are more transparent than ETFE.

Regarding the amount of light through the film vs amount of power for photosynthesis, only about 500W/m2 at Earth's surface is visible light, and of that about 300W/m2 is really useful photosynthetically. So grow lights only need to produce 300W/m2 of visible light (red/blue, the most efficient although all visible light is photosynthetically useful). That can be cut down by using intracanopy lighting and glow lights directly above the plant.

The actual spectrum of light on Mars would be something more like what we see in space, with strong red scattering. Blue and green are there, they aren't absorbed as much by the smaller air mass of Mars althought they are somewhat directly blocked by dust. So what light there is on Mars is pretty good as far as quality goes, although subject to dust levels.

https://pdfs.semanticscholar.org/386c/c62389c573f3215e8ebbf00a1d2032f888f6.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/30/2019 02:46 pm
Thank you to all that wrote or sent references.
From two slightly aged papers and the hoop stress equations, it would appear that a lobed structure of polyethylene, with lobes 1m wide or smaller and reinforced with fibers at the lobe junctions and longitudinal fibers would be OK.  Probably two or more layers of 1mm poly.  About 3 kg/m2 for full Earth pressure.
Light transmittance would be about 50%.  Some form of removable multi-layer insulation would be required to reduce night time heat losses.  Some supplementary artificial lighting would help keep the mass down and increase productivity.
Worth bearing in mind that to a 0th order of magnitude, the solar spectrum as emitted by the sun provides ~96lm/W.
The ~1050W/m^2 of light at the earths surface peak if you  feed it through a 20% efficient solar panel however, you get 210W.
With 10% loss electrical path,  and the most efficient LEDs, you need ~600W to produce equivalent amount of light per m^2.

So, the 'transmissivity' of PV-LED can be ~30%, not 20%.

This is as significant smount of solar energy comes in more infrared than is usable by either plant or eye.

Unfortunately, the sources I find on wikipedia and otherwise do not do the proper calculation, so I can't quite find the accurate number.
They for example integrate over a nominal truncated 5800K spectrum instead of the solar spectrum at the surface of earth to compute lm/W.

I am looking for relevant data to do this better.




This has probably been done to death in the Scaling Agriculture on Mars thread but here's the info anyway.

What you're after is Photosynthetically Active Radiation (PAR), which is typically measured as Photosnythetic Photon Flux (PPF) in micromoles per square metre per second, or moles per day (as in the 10^23 kind, moles being # of photons). That's useful photons in the visible range as mentioned in my previous post.

Conversion efficiency is usually given in umol:W. A sunny day has an excess of moles to grow plants (50), and an overcast winter's day can give you only 10% of that. But even an overcast summer day can only give like ~5 mol. Martian sunlight, save for dust storms, is going to be very reliable in that regard.

LED lights are getting better and better every year. The "blurple" works out most efficient because of energy but plant quality is an issue and not all respond that well to it. Green light, will less useful, still penetrates into a lead's deeper cells and is reabsorbed, or scattered. Some plants respond best to green because that's what penetrates through a canopy.

Note that the best commercial LEDs still need a lot of cooling, and will fail if they are run too hot. This problem is compounded in space because not only do you lack spares but you are surrounded by a perfectly insulating vacuum. Also, if they are run 24/7, the lights will eventually fail after 5-6 years. The weak point is the circuitry. Add in cosmic radiation and you are looking at a further lifespan reduction. If you were NASA you could make the LEDs out of unicorn hair and rainbows and cost $5million apiece, but on a commercial scale you'll just have to run on replacements and have a decent stock to last a couple of synods.

Another thing they don't tell you is that LEDs don't immediately fail.... they degrade over time. Manufacturer performance ratings are usually "time to 70% output" mark.

http://www.greenhouse.cornell.edu/structures/factsheets/Greenhouse%20Lighting.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: speedevil on 07/30/2019 02:53 pm
Thank you to all that wrote or sent references.
From two slightly aged papers and the hoop stress equations, it would appear that a lobed structure of polyethylene, with lobes 1m wide or smaller and reinforced with fibers at the lobe junctions and longitudinal fibers would be OK.  Probably two or more layers of 1mm poly.  About 3 kg/m2 for full Earth pressure.
Light transmittance would be about 50%.  Some form of removable multi-layer insulation would be required to reduce night time heat losses.  Some supplementary artificial lighting would help keep the mass down and increase productivity.
Worth bearing in mind that to a 0th order of magnitude, the solar spectrum as emitted by the sun provides ~96lm/W.
The ~1050W/m^2 of light at the earths surface peak if you  feed it through a 20% efficient solar panel however, you get 210W.
With 10% loss electrical path,  and the most efficient LEDs, you need ~600W to produce equivalent amount of light per m^2.

So, the 'transmissivity' of PV-LED can be ~30%, not 20%.

This has probably been done to death in the Scaling Agriculture on Mars thread but here's the info anyway.

What you're after is Photosynthetically Active Radiation (PAR), which is typically measured as Photosnythetic Photon Flux (PPF)

I am aware of PAR and the other things you mention, I was more meaning properly integrating over the actual solar spectrum at earth/Mars for various panels and correctly calculating for best white and color optimised near-term sources.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/30/2019 03:02 pm
I am aware of PAR and the other things you mention, I was more meaning properly integrating over the actual solar spectrum at earth/Mars for various panels and correctly calculating for best white and color optimised near-term sources.


Oh, you mean as in supplemental grow lights? The actual solar spectrum is quite variable even through the day and in various shade conditions but I guess commercial white grow lights will do the job just fine?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/31/2019 01:20 pm
Phase II colony.
At this point there have been 4 Starship cargos and 2 crewed starships to Mars.
Population is about 15-30 people, more or less.

There are some safety problems with this arrangement, this ships being pretty obviously too close if they serve as propellant tanks.  On the other hand, these are probably the two first cargo ships and a another one from the second wave.  So perhaps these will no longer move.

The fuel production area in the forefront has an ice unloading area, production containers and a CO2 compression system.  This would feed the starships that are supposed to return to Earth, probably somewhere outside the image.  There is enough production capacity illustrated for two staships.

This pretty much follows the tile model designed earlier, I'm looking for problems and solutions to the colony arrangement.

Thoughts and criticisms?


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 12:30 am
Moved the two original ships and integrated them into the base.

The plan is that the second wave (4 ships) will include a trio of carriers similar to the one presently being used to move hopper around.  They can move the two original ships around, as well as set up two of the second wave's ships to launch.  Don't quite know yet what to do with the other two ships.  Perhaps they will leave with the ships of the third sinod, four years after landing?  Seems like  a long time.

An obvious use for one of the ships that gets integrated into toe settlement is as... a water tank  ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 03:04 am
A bit more atmosphere and a bit more messy.
Title: Re: Envisioning Amazing Martian Habitats
Post by: aero on 08/01/2019 04:21 am
I like the depiction of the elevator shaft. Wouldn't it be more useful though if the elevator were on a transporter-erector so that it could cozy up to the starship after it cooled from landing? That would be much more forgiving of landing point offsets by a few meters or a 100 meters. Heck, it would work even if the landing point was a Km offset. That way much of the crew could promptly disembark to ground transport then moved to quarters or recovery depending on how well or poorly they had coped in space?

An elevator on an erector would serve similarly to a mobile crane, only being constrained to smaller components. That is, a crane would be better for offloading an assembled dozer. But an elevator has a speed advantage due to familiarity and simplicity of operation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 12:15 pm
I like the depiction of the elevator shaft. Wouldn't it be more useful though if the elevator were on a transporter-erector so that it could cozy up to the starship after it cooled from landing? That would be much more forgiving of landing point offsets by a few meters or a 100 meters. Heck, it would work even if the landing point was a Km offset. That way much of the crew could promptly disembark to ground transport then moved to quarters or recovery depending on how well or poorly they had coped in space?

An elevator on an erector would serve similarly to a mobile crane, only being constrained to smaller components. That is, a crane would be better for offloading an assembled dozer. But an elevator has a speed advantage due to familiarity and simplicity of operation.
Yes, at the spaceport I expect there will be something just like you describe.  I modeled it already in the following images.  What you see in the earlier image are two ships that have been placed to become permanent parts of the base.  That is why they are so close and the elevator is fixed.  One of the two is a water tower, and might also serve as lightly pressurized nitrogen tank.  The other is undefined at this point.  May even decide to use one of the Spaceships with an internal habitat, and then it becomes extra living space.
The carriers in the spaceport images are a bit outdated, would probably use (almost) straight off the shelf units such as those recently used to move Hopper.  The carrier can do double duty, carry the tower, and cary the ship when empty. 
Looking forwards to the next SpaceX presentation and Hopper testing program, I wonder if there will be some kind of mobile flame trench.  Pad damage from a fully loaded take off is probably going to be much more severe than from a landing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 01:16 pm
Updated the carrier and integrated the flame trench into the landing pad.  Now, to work out a reasonable set of doors...Space 1999 seems like a good inspiration.  Or Thunderbirds....
Title: Re: Envisioning Amazing Martian Habitats
Post by: Steve D on 08/01/2019 03:04 pm
Moved the two original ships and integrated them into the base.

The plan is that the second wave (4 ships) will include a trio of carriers similar to the one presently being used to move hopper around.  They can move the two original ships around, as well as set up two of the second wave's ships to launch.  Don't quite know yet what to do with the other two ships.  Perhaps they will leave with the ships of the third sinod, four years after landing?  Seems like  a long time.

An obvious use for one of the ships that gets integrated into toe settlement is as... a water tank  ;)

Have you considered having the living areas of the first starships cut off of the top of the fuel tanks and grouped together forming on large habitat that would not require spacesuits to go from one ship to another and having the tank sections grouped a distance away to function as a tank farm for propellant? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Pete on 08/01/2019 03:26 pm
My personal take:
1- A purely solar Mars colony is possible.  The solution to the darkest dust storms (Opportunity killers) is overbuilding the solar farm to produce excess propellant storage, and burn the excess during the dark times.  For the rest of the storm, reduce propellant production.  Solar still has some output during storms.
Dust storm can last for 60 days, and filters out up to 99.8% of incoming light at the surface. Good luck running solar on the 1/500th of a mars sun. Or even at 1/50th, from a minor dust storm.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 03:36 pm
Moved the two original ships and integrated them into the base.

The plan is that the second wave (4 ships) will include a trio of carriers similar to the one presently being used to move hopper around.  They can move the two original ships around, as well as set up two of the second wave's ships to launch.  Don't quite know yet what to do with the other two ships.  Perhaps they will leave with the ships of the third sinod, four years after landing?  Seems like  a long time.

An obvious use for one of the ships that gets integrated into toe settlement is as... a water tank  ;)

Have you considered having the living areas of the first starships cut off of the top of the fuel tanks and grouped together forming on large habitat that would not require spacesuits to go from one ship to another and having the tank sections grouped a distance away to function as a tank farm for propellant?
Yes, and I didn't choose this path because, as far as I understand it, the two first ships will not have living areas, they will be cargo ships.  After the first two ships, I think it will make sense to return all the Ships back to Earth. 
I think it's a tall order to refuel 4 ships for the second synod, so I plan to just have two fueled.
This leaves me with two extra ships that I plan to fuel for the third synod, so they will spend 4 years on Mars.  I hope that by then we either have a nuclear reactor and lots'a power, or lighter solar cells, or even some locally produced cells,or at least cell structural supports.  So again, lots'a power.
I did illustrate earlier on a whole series of bases built from large pressure vessels shipped by gator type Starships.  IonMars is the brain behind that solution.  Eventually SpaceX will decide something, and we'll see what is the favored solution.

There is also the question of sequencing launches.  Do we return ships as soon as possible, a week or so after they have landed, so we need to have storage capacity, or do we return ships after 2 years, when they have been fueled up and can serve as their own storage tanks?  This probably depends on how cheap propellant storage can be, as well as the rate at which power units can be sent to Mars.  Or we can start one way, and then switch.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 03:50 pm
My personal take:
1- A purely solar Mars colony is possible.  The solution to the darkest dust storms (Opportunity killers) is overbuilding the solar farm to produce excess propellant storage, and burn the excess during the dark times.  For the rest of the storm, reduce propellant production.  Solar still has some output during storms.
Dust storm can last for 60 days, and filters out up to 99.8% of incoming light at the surface. Good luck running solar on the 1/500th of a mars sun. Or even at 1/50th, from a minor dust storm.
The sentence you refer to mentions burning excess fuel production.  The dust storms last 60 days, but the very dark periods are not that long.  In addition, we would not be running the base at full power, but at a minimum rate, with no propellant and no food production.  This would reduce the power demand by about 95%.  Most of the energy required at low load will be heating, and that can be done with about 95% efficiency with natural gas boilers.  The lighting and computers can be run off a generator, that burns methane and LOX at about 40% efficiency.
So if we have a 2 MW peak load power system, it can be supported by a 100 kW electrical generator and a 100 kW boiler.   These are are very conventional pieces of equipment.
I don't think there is any luck involved.  A minimum amount of planning is required, however.  My point , see item 2, was that nuclear in nice, but not a showstopper.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Steve D on 08/01/2019 04:01 pm
Moved the two original ships and integrated them into the base.

The plan is that the second wave (4 ships) will include a trio of carriers similar to the one presently being used to move hopper around.  They can move the two original ships around, as well as set up two of the second wave's ships to launch.  Don't quite know yet what to do with the other two ships.  Perhaps they will leave with the ships of the third sinod, four years after landing?  Seems like  a long time.

An obvious use for one of the ships that gets integrated into toe settlement is as... a water tank  ;)

Have you considered having the living areas of the first starships cut off of the top of the fuel tanks and grouped together forming on large habitat that would not require spacesuits to go from one ship to another and having the tank sections grouped a distance away to function as a tank farm for propellant?
Yes, and I didn't choose this path because, as far as I understand it, the two first ships will not have living areas, they will be cargo ships.  After the first two ships, I think it will make sense to return all the Ships back to Earth. 
I think it's a tall order to refuel 4 ships for the second synod, so I plan to just have two fueled.
This leaves me with two extra ships that I plan to fuel for the third synod, so they will spend 4 years on Mars.  I hope that by then we either have a nuclear reactor and lots'a power, or lighter solar cells, or even some locally produced cells,or at least cell structural supports.  So again, lots'a power.
I did illustrate earlier on a whole series of bases built from large pressure vessels shipped by gator type Starships.  IonMars is the brain behind that solution.  Eventually SpaceX will decide something, and we'll see what is the favored solution.

There is also the question of sequencing launches.  Do we return ships as soon as possible, a week or so after they have landed, so we need to have storage capacity, or do we return ships after 2 years, when they have been fueled up and can serve as their own storage tanks?  This probably depends on how cheap propellant storage can be, as well as the rate at which power units can be sent to Mars.  Or we can start one way, and then switch.

The first 2 ships would be cargo ships but they would be pressurized cargo vehicles that would need some type of minimal life support. Temperature and pressure controls at minimum, air recycling would be needed for the people that go in and get the supplies out. Once emptied it could provide much needed open space for recreation, food storage, exercise. (anyone interested in 1/3rd g circular racketball?) Inside it could be outfited with decks scavenged from the packing material used to support the cargo (you wont just pile 100 tons of cargo in the middle of a room) or locally sourced materials.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 04:23 pm
Moved the two original ships and integrated them into the base.

The plan is that the second wave (4 ships) will include a trio of carriers similar to the one presently being used to move hopper around.  They can move the two original ships around, as well as set up two of the second wave's ships to launch.  Don't quite know yet what to do with the other two ships.  Perhaps they will leave with the ships of the third sinod, four years after landing?  Seems like  a long time.

An obvious use for one of the ships that gets integrated into toe settlement is as... a water tank  ;)

Have you considered having the living areas of the first starships cut off of the top of the fuel tanks and grouped together forming on large habitat that would not require spacesuits to go from one ship to another and having the tank sections grouped a distance away to function as a tank farm for propellant?
Yes, and I didn't choose this path because, as far as I understand it, the two first ships will not have living areas, they will be cargo ships.  After the first two ships, I think it will make sense to return all the Ships back to Earth. 
I think it's a tall order to refuel 4 ships for the second synod, so I plan to just have two fueled.
This leaves me with two extra ships that I plan to fuel for the third synod, so they will spend 4 years on Mars.  I hope that by then we either have a nuclear reactor and lots'a power, or lighter solar cells, or even some locally produced cells,or at least cell structural supports.  So again, lots'a power.
I did illustrate earlier on a whole series of bases built from large pressure vessels shipped by gator type Starships.  IonMars is the brain behind that solution.  Eventually SpaceX will decide something, and we'll see what is the favored solution.

There is also the question of sequencing launches.  Do we return ships as soon as possible, a week or so after they have landed, so we need to have storage capacity, or do we return ships after 2 years, when they have been fueled up and can serve as their own storage tanks?  This probably depends on how cheap propellant storage can be, as well as the rate at which power units can be sent to Mars.  Or we can start one way, and then switch.

The first 2 ships would be cargo ships but they would be pressurized cargo vehicles that would need some type of minimal life support. Temperature and pressure controls at minimum, air recycling would be needed for the people that go in and get the supplies out. Once emptied it could provide much needed open space for recreation, food storage, exercise. (anyone interested in 1/3rd g circular racketball?) Inside it could be outfited with decks scavenged from the packing material used to support the cargo (you wont just pile 100 tons of cargo in the middle of a room) or locally sourced materials.
According to the SpaceX plan, and most other plans as well, there are no people to move supplies in and out of the first two ships.  And I absolutely agree that the space might be usable, that is why I have integrated them into the colony and provided an elevator.  I guess the question might be, how heavy and complex would be a crane that can remove the top off a starship, compared to the cost of an elevator that allows you to keep that top in place. 
Here are some images of how I imagine the cargo will be stored in the ship.  I use unit load devices, that are basically subsets of ISO containers.  The system, an ASRS pivots the entire cargo load so elements can be put in front of the doors, and so do away with floors, trapdoors, cargo elevators and other mass gobblers.  It's more a concept than a real device though :-)
https://en.wikipedia.org/wiki/Automated_storage_and_retrieval_system
Title: Re: Envisioning Amazing Martian Habitats
Post by: Steve D on 08/01/2019 05:35 pm
But do you really want to live on top of the tank farm?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/01/2019 07:20 pm
But do you really want to live on top of the tank farm?
Well, if it was the propellant tank farm, no.  If used as a water tank, at least for one ship like I propose, yes.  The other one is a problem though.  Kind of sad to have such a high point, with no point of view.

It the two first ships serve as tanks for the next ships, that's another solution, and I would have them a fair distance away.

Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 08/02/2019 12:44 am
My personal take:
1- A purely solar Mars colony is possible.  The solution to the darkest dust storms (Opportunity killers) is overbuilding the solar farm to produce excess propellant storage, and burn the excess during the dark times.  For the rest of the storm, reduce propellant production.  Solar still has some output during storms.
Dust storm can last for 60 days, and filters out up to 99.8% of incoming light at the surface. Good luck running solar on the 1/500th of a mars sun. Or even at 1/50th, from a minor dust storm.
A pet idea I often bring up is to create a large body of water under the surface for a whole list of advantages such as robust earth pressure, a sizable biosphere, radiation shielding, exploiting waste heat, practically self-assembles (you just need an insulating roof material eg saline filled plastic sausages that is a bit lighter than water.

Could you also exploit this for a practically limitless battery? There is also something similar for storing thermal energy across seasons: https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storage .. but I was also wondering if there could be some sort of clever battery for not horribly inefficient electricity storage.. powered by the phase transition of water to ice, or mixing fresh and saline water, or perhaps a literal capacitor where you have two pools several kilometers apart. (just throwing ideas out at this point)

I googled "salt water capacitor". Honestly I don't even know if this clip is real or a joke done in aftereffects :)

https://www.youtube.com/watch?v=QuZPQrs227Q
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 08/02/2019 05:59 am
I like the depiction of the elevator shaft. Wouldn't it be more useful though if the elevator were on a transporter-erector so that it could cozy up to the starship after it cooled from landing? That would be much more forgiving of landing point offsets by a few meters or a 100 meters. Heck, it would work even if the landing point was a Km offset. That way much of the crew could promptly disembark to ground transport then moved to quarters or recovery depending on how well or poorly they had coped in space?

An elevator on an erector would serve similarly to a mobile crane, only being constrained to smaller components. That is, a crane would be better for offloading an assembled dozer. But an elevator has a speed advantage due to familiarity and simplicity of operation.

Why not give the transporter - erector a bit more muscle and have it grab the landed and cooled SS, lay it horizontal and move it to an un-loading dock where cargo and vehicles could be driven on/off instead of craned 30+ metres ?

Mick.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 08/02/2019 06:27 am
A thought about uses for early, non returned Starships.

Strip out most of the engines and any other equipment which can be used as spare parts.  Leave the SS in a flyable condition for short, in atmosphere flights (long hops) and use it for a remote, short term exploration/scientific base.

Load up with supplies, a pair of small rovers research equipment at the main settlement.  Hop some hundreds of kilometres away for a week or so and return to re-stock and unload samples before going somewhere else.  Relatively easy access to just about anywhere from the bottom of Hellas to the top of Olympus.  Only really limited by the consumables on board.

Mick.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Yggdrasill on 08/02/2019 09:58 am
Since this thread is about *amazing* martian habitats, what about this:

- A solid steel frame supporting a pool of water, with living space underneath. The pool has walls and floors of thick ETFE polymer, so that light passes through the pool into the living area.
- The pool overhangs out from the area of the living space in all directions by several meters, and provides adequate radiation shielding.
- The pool has a lightweight ETFE roof structure and a pressurized environment, so the residents can use the pool for swimming.
- The living space has floor to ceiling windows made out of ETFE, so you get uninterrupted views of the martian surface.

I'm thinking this is basically a villa you could have some time in the future, when there is over 1 million inhabitants.  ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/02/2019 01:35 pm
Updated and simplified spaceport.
The propellant is stored in Starships that are static, and transferred to the Starship that is about to take off on the pad.  This way there is no need to move a fuelled Starship, that would be very heavy, and the landing pad can also serve as take-off pad and is always clear.  Only one pad will be required at first, reducing the overall work required.

The berm is a safety precaution against pad elements flying off at take off.  The pad is kept clean in general and should not eject dust, except what might break off from the pad itself.

It might be interesting to put a foot or so of ice under a starship taking off, but I wonder if I'm just replacing flying chips of mars concrete with flying chips of ice.

Another alternative might be to strip the thermal shield from two first Starships and lay it on the ground in some kind of concrete.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/02/2019 08:02 pm
And here is the result of the latest design spree.  Six starships, 3 buried habitats, lots and lots of solar (about 4-5 MW of power)  and propellant production facilities.
This is at the end of the second synod, so 4 years have passed since the first automated landing.  Humans have been on Mars for 2 years at this point.

Most of the base is simply bulldozed regolith.  The habitats are inflatables and the equipment is pre packaged on Earth.

The next synod will see a lot of in-situ resource work started, as the technologies for glass, steel and other building materials are developed.  Large scale food production should start as well. All depends on the available power, however.

The view from a Starship at Spaceport shows the small colony as seen from the RLW (Ridiculously Large Window)  ;-)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/03/2019 07:17 am
Why not give the transporter - erector a bit more muscle and have it grab the landed and cooled SS, lay it horizontal and move it to an un-loading dock where cargo and vehicles could be driven on/off instead of craned 30+ metres ?

A machine that's designed to safely grab, tilt horizontal, and support a top-heavy (full cargo) spaceship would be much more demanding than one designed to simply lift down the cargo.

(The SS launch ops don't include a TEL; a transporter, presumably, but not an erector. It gets built vertically, launched and landed vertically. The only time it goes horizontal is a short window during re-entry.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/03/2019 07:33 am
[berms]

I'm not sure that ring berm would achieve much. Ballistically, it looks like anything that skims just over the berm will have exactly the range to hit the base. It will also do very little against a full RUD of a SS.

Better, IMO, to deal with the hassle of having the launch/landing pad further away from everything else, particularly the base-proper, and put smaller berms around the things you are trying to protect, at the full height of those things.

For example, how big of a protected fuel-transport-vehicle bunker could you build near the launch pad for the same volume of material as that ring-berm? Low long a road could you level and fill, from the base to the pad, for the same amount of work?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 08/03/2019 07:45 am
By making that berm in an arc of about 120 degrees you could build it 3 x higher with roughly the same amount of material and still cover all the illustrated infrastructure.

OR, put the launch/landing pad in a depression or small crater.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/03/2019 11:54 am
By making that berm in an arc of about 120 degrees you could build it 3 x higher with roughly the same amount of material and still cover all the illustrated infrastructure.
OR, put the launch/landing pad in a depression or small crater.

Same issue. You want the berm, wall or protective shield to be as close as possible to the thing you are trying to protect, and as far as possible from the source of danger. It drastically reduces the range of trajectories that can cross over the berm/wall/shield but still come down on the thing you care about. It also means the things with that trajectory must be lofted, lowering the range of velocities that can achieve the right angle.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 08/03/2019 12:35 pm
Launchpad: dig a moderate depression. Then as early as possible the ground must be sealed unless there is rock!

Alternatively a flame deflector and a raised platform above for Starship. Neither are impossible. (Ground still needs sealing tho). Moving empty Starships on SPMT transporters will be easy, having hauled a custom transporter there. So 1 good launch pad will be enough. I think up-thread there were lots of excellent ideas and renders!

Martian "concrete" is pretty important. Has this been discussed? I am aware of the Lunacrete ideas, but mars has different geology and conditions.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/03/2019 01:59 pm
By making that berm in an arc of about 120 degrees you could build it 3 x higher with roughly the same amount of material and still cover all the illustrated infrastructure.
OR, put the launch/landing pad in a depression or small crater.

Same issue. You want the berm, wall or protective shield to be as close as possible to the thing you are trying to protect, and as far as possible from the source of danger.

The first part is correct, but the bold part is wrong.

Flying debris is approximately an inverse square process. Just like with light propagation (another inverse square process), it is area-efficient to block photons from hitting X either by covering the lightbulb OR by covering X (eg if X is your retina, you might put on an eye mask). Either strategy works well.

Naturally in this case you would want to do both — berms near the launch/landing pad AND berms protecting high-value structures.

It drastically reduces the range of trajectories that can cross over the berm/wall/shield but still come down on the thing you care about. It also means the things with that trajectory must be lofted, lowering the range of velocities that can achieve the right angle.

All these advantages apply to landing/launch pad berms too. Since ballistic physics is (mostly) time-reversible, you can geometrically reverse all of these statements and use them to argue for pad-side berms too.

A big factor here is relative quantity. If there are 100x as many structures within the hazard radius to protect as there are landing pads per structure, then obviously you allocate relatively more resources to shielding the pad. Or vice-versa.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/03/2019 02:35 pm
As I am feeling contrarian today, I will just state that the design supposes that the projectile problem has been solved at the source, I.E. there are no projected rocks and the berm is just there to control surface dust deposited between the last time they passed the pad cleaning machine and take-off/landing.

I don't think landing is a significant issue, except for the first two synods, as there will not be a pad built.

Moving the ships shouldn't be an issue either.  The very simple method SpaceX has used for Hopper seems like a given for Mars in the future, so wherever the ships land, they can be moved by a trio of self propelled movers.  These can move at 5km per hour, probably less when loaded, but anyway.

The questions I want to raise with this image are really about take-off and the effects on the ship exhaust plume on the ship and/or the environment.

-Can a rocket take off from a plane surface or is it necessarily damaged by the power of its own exhaust plume?  Note that Hopper has already demonstrated that a single engine works.  So for Starship we have six more engines to go.  How many engines is too many engines and how do we know that?

-Rocket hold downs are there to keep the rocket from drifting into the support tower.  If there is no tower, there is no need for the hold downs, if the pad is wide enough?

-Can a pad be strong enough to stand up to a rocket plume? 

-If not we need a flame trench, as per the soviet launch pads, for example.  The Kennedy trenches are shallow because of Florida flatness, hence a launch mound. But on Mars there is geology.  So a cliff might be good, but again that still means a lot of construction, as cliffs are not necessarily robust, nearby and building any kind of overhanging structures means  foundations and concrete.

All ideas that involve craters, distance or higher berms are not solving the problem at the source.  And are replacing good design with extensive civil works, on the basis of what may be faulty analogies.  :D

Again: eliminate the danger, don't mitigate the danger.  So can we eliminate the danger by building a strong pad, and can a Starship survive its own engines in a pad configuration?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/03/2019 02:43 pm
[berms]

I'm not sure that ring berm would achieve much. Ballistically, it looks like anything that skims just over the berm will have exactly the range to hit the base. It will also do very little against a full RUD of a SS.

Better, IMO, to deal with the hassle of having the launch/landing pad further away from everything else, particularly the base-proper, and put smaller berms around the things you are trying to protect, at the full height of those things.

For example, how big of a protected fuel-transport-vehicle bunker could you build near the launch pad for the same volume of material as that ring-berm? Low long a road could you level and fill, from the base to the pad, for the same amount of work?
I don't want to become the new Vauban  ;D
But yes, just build a long road is probably going to be the final conclusion.  I just like the idea of being able to put ships holding propellant near the take off point.  So that will mean a cliff and a trench, I expect.  but if I can avoid it I will.
RUD at take-off would be really anoying.  And berm's won't help for that!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/03/2019 03:08 pm
Launchpad: dig a moderate depression. Then as early as possible the ground must be sealed unless there is rock!

Alternatively a flame deflector and a raised platform above for Starship. Neither are impossible. (Ground still needs sealing tho). Moving empty Starships on SPMT transporters will be easy, having hauled a custom transporter there. So 1 good launch pad will be enough. I think up-thread there were lots of excellent ideas and renders!

Martian "concrete" is pretty important. Has this been discussed? I am aware of the Lunacrete ideas, but mars has different geology and conditions.
Yes, fairly extensively.  I am aware of three possibilities:
1- Sulfur based Marscrete, made a splash in 2016, been quiet since.
https://arxiv.org/abs/1512.05461
2- Magnesium based concrete.  Strong and durable. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2017EA000353
3- Classic concrete from Carbonates that have been found on Mars.  https://en.wikipedia.org/wiki/Carbonates_on_Mars

Water availability is better than expected on Mars, so I think the conventional solution will probably be used.

Alternatively you have all the block based products:
-Sintered regolith.
-Compressed regolith.
-More or less standard bricks baked from Martian clays.
-Concrete in block forms.
-Ceramic bricks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/03/2019 03:50 pm
It drastically reduces the range of trajectories that can cross over the berm/wall/shield but still come down on the thing you care about. It also means the things with that trajectory must be lofted, lowering the range of velocities that can achieve the right angle.
All these advantages apply to landing/launch pad berms too. Since ballistic physics is (mostly) time-reversible, you can geometrically reverse all of these statements and use them to argue for pad-side berms too.

No. Look at the distance between the launch pad and the ring-berm, it covers almost no vertical angle relative to the launch vehicle. A berm at the item-to-be-protected could be much closer, hence protect against a larger vertical angle.

A big factor here is relative quantity. If there are 100x as many structures within the hazard radius to protect as there are landing pads per structure, then obviously you allocate relatively more resources to shielding the pad. Or vice-versa.

I'm going by the image. The area enclosed by the ring is vastly larger than the structures that need to be protected (except for the ships-as-tanks. And the ring-berm does nothing to protect those anyway.)



As I am feeling contrarian today, I will just state that the design supposes that the projectile problem has been solved at the source, I.E. there are no projected rocks and the berm is just there to control surface dust deposited between the last time they passed the pad cleaning machine and take-off/landing.

With LOx, LOx+fuel, pressure vessels, and moving vehicles full of same, you have to assume the worst case can happen and protect against it. A RUDding SS would be a disaster, it could set the colony back many years. A RUDding SS that breaches every surrounding hab module with shrapnel would be a one-stop colony killer.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/03/2019 04:27 pm


With LOx, LOx+fuel, pressure vessels, and moving vehicles full of same, you have to assume the worst case can happen and protect against it. A RUDding SS would be a disaster, it could set the colony back many years. A RUDding SS that breaches every surrounding hab module with shrapnel would be a one-stop colony killer.

So what about this image and this berm?  Will the whole thing be laid waste if Hopper blows up?  I realise we're talking about 1:10th of the power, but still...
And Starship will not blow up.  If it does, the whole concept is down the drain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/04/2019 09:00 am
And Starship will not blow up.  If it does, the whole concept is down the drain.

Ouch. That is not a good plan.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/04/2019 09:09 am
So what about this image and this berm?  Will the whole thing be laid waste if Hopper blows up?

(https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1574579;image) (https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41427.0;attach=1574579;image)

Yes. That berm is purely a exhaust deflector because everything is so close. If the Hopper RUDs with full prop load, those tanks and associated hardware are trash. I assume they've decided that the cost of rebuilding is small enough vs having proper distance/etc to that infrastructure. But it's not a good guide for anything you can't replace quickly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Steve D on 08/04/2019 03:22 pm
How would a starship blowing up on Mars actually work? On earth there is a large amount of oxygen in the atmosphere which enables all of the fuel to burn. On Mars its a near vacuum with no oxygen. How fast would a starship fully loaded with fuel and oxygen that breaches its tanks burn? How quickly would the fuel and oxygen disperse to where it wouldnt burn any more? If just one tank is breached there wouldnt be any fire or explosion.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/04/2019 04:06 pm
How would a starship blowing up on Mars actually work? On earth there is a large amount of oxygen in the atmosphere which enables all of the fuel to burn. On Mars its a near vacuum with no oxygen. How fast would a starship fully loaded with fuel and oxygen that breaches its tanks burn? How quickly would the fuel and oxygen disperse to where it wouldnt burn any more? If just one tank is breached there wouldnt be any fire or explosion.
Is the Spaceport a part of the habitat? Perhaps we should start a Spaceport thread?  It's perhaps too specific to fit here?
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 08/04/2019 04:17 pm
Excellent idea. It would make it easier to (find and) refer back to specific ideas later.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Pete on 08/04/2019 04:28 pm
So what about this image and this berm?  Will the whole thing be laid waste if Hopper blows up?
Yes, absolutely.

How about an image of a fuel tanker standing next to a sidewalk, with the same caption? "If this blows up, will that sidewalk save us"

No, because that's not what it is there for. And that Berm is not there for that purpose either.

Edit/Lar: Remove snark
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/04/2019 05:18 pm
So what about this image and this berm?  Will the whole thing be laid waste if Hopper blows up?
Yes, absolutely.

How about an image of a fuel tanker standing next to a sidewalk, with the same caption? "If this blows up, will that sidewalk save us"

No, because that's not what it is there for. And that Berm is not there for that purpose either.

Actually, I know very little about berms, exploding rockets and launching pad design.  It was an honest question, sorry if it sounded sarcastic, it was not my intent.  I really am that ignorant.

Title: Re: Envisioning Amazing Martian Habitats
Post by: AC in NC on 08/04/2019 05:41 pm
Actually, I know very little about berms, exploding rockets and launching pad design.  It was an honest question, sorry if it sounded sarcastic, it was not my intent.  I really am that ignorant.

Ignore it.  Pete woke up on the wrong side of the bed this morning.  He ripped someone else in another thread as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/04/2019 09:15 pm
As I am feeling contrarian today, I will just state that the design supposes that the projectile problem has been solved at the source, I.E. there are no projected rocks and the berm is just there to control surface dust deposited between the last time they passed the pad cleaning machine and take-off/landing.

If we could just declare problems solved, then everything gets a lot easier. Unfortunately reality is quite indifferent to such declarations.

All ideas that involve craters, distance or higher berms are not solving the problem at the source. And are replacing good design with extensive civil works.

When people get killed if there's a failure, you want multiple layers of protection. That means distance AND berms/craters/natural topology AND a hard prepared pad.

Take any single one of those mitigation strategies off the table, and the total system cost rises. Why? Because to compensate now you have to overbuild the remaining strategies, pushing them deeper into less favorable parts of their cost/benefit curve.

Dismissing distance as a possible strategy is especially problematic. You're constraining yourself to cluster all the buildings right next to the landing pad, seemingly for no reason.

on the basis of what may be faulty analogies.  :D

Until we do it on Mars, all analogies "may" be faulty. This fear/uncertainty/doubt can be equally applied to anything on Mars.
 

Again: eliminate the danger, don't mitigate the danger.  So can we eliminate the danger by building a strong pad, and can a Starship survive its own engines in a pad configuration?

"Eliminate" the danger? No. A strong pad alone can't eliminate all the dangers from a landing rocket carrying many tonnes of explosives.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/04/2019 09:21 pm
It drastically reduces the range of trajectories that can cross over the berm/wall/shield but still come down on the thing you care about. It also means the things with that trajectory must be lofted, lowering the range of velocities that can achieve the right angle.
All these advantages apply to landing/launch pad berms too. Since ballistic physics is (mostly) time-reversible, you can geometrically reverse all of these statements and use them to argue for pad-side berms too.

No. Look at the distance between the launch pad and the ring-berm, it covers almost no vertical angle relative to the launch vehicle. A berm at the item-to-be-protected could be much closer, hence protect against a larger vertical angle.

Yes I know, those berms are too short and the pad is too close. :P That doesn't subtract anything from what I said.

The cheapest pad berm option afaict is to put the pad further away and have a single linear berm (or natural hill) in the direction of the colony.

A big factor here is relative quantity. If there are 100x as many structures within the hazard radius to protect as there are landing pads per structure, then obviously you allocate relatively more resources to shielding the pad. Or vice-versa.

I'm going by the image.

Of course. I'm trying to articulate design principles that are applicable in general, not just applicable to the latest rendering.


The area enclosed by the ring is vastly larger than the structures that need to be protected (except for the ships-as-tanks. And the ring-berm does nothing to protect those anyway.)

Astute analysis.

Aren't general principles great? You can apply them to any particular situation. :D


As I am feeling contrarian today, I will just state that the design supposes that the projectile problem has been solved at the source, I.E. there are no projected rocks and the berm is just there to control surface dust deposited between the last time they passed the pad cleaning machine and take-off/landing.

With LOx, LOx+fuel, pressure vessels, and moving vehicles full of same, you have to assume the worst case can happen and protect against it. A RUDding SS would be a disaster, it could set the colony back many years. A RUDding SS that breaches every surrounding hab module with shrapnel would be a one-stop colony killer.

Completely agree.


edit: removed an inconsiderate phrase; my apologies to lamontagne
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/04/2019 11:02 pm
I know the pad is too close.  I understand the berm is too small for an explosion.  I realize the best solution is probably to put the ship 1 km or 2 away. I illustrated all that a few months ago.
I was merely asking, not doubt very poorly, from the reactions, if it was possible to find a solution that allowed for a close pad.
The render of the day remark was very hurtful.  I don’t think I deserved it. Frankly, I don’t understand how it could be said in such a way.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/05/2019 01:08 am
I know the pad is too close.  I understand the berm is too small for an explosion.  I realize the best solution is probably to put the ship 1 km or 2 away. I illustrated all that a few months ago.
I was merely asking, not doubt very poorly, from the reactions, if it was possible to find a solution that allowed for a close pad.
The render of the day remark was very hurtful.  I don’t think I deserved it. Frankly, I don’t understand how it could be said in such a way.

Lamontagne, my sincere apologies for hurting you with my very poorly chosen words. That was not my intent at all. Please permit me to re-phrase.

Because the community's exploration of this large design space moves so rapidly, and because lamontagne is so fantastically productive, and so graciously responsive to our (sometimes inartfully expressed) feedback, I think it's most useful to try articulating general principles beyond saying things that only apply to the latest rendering. If we can agree on a toolkit of general principles, anyone can use constraint satisfaction to more-or-less "derive" a Mars-suitable design for any particular situation and goal.


Again, my deepest apologies lamontagne for giving offense, and double so to such a kind and generous fellow member. I am truly sorry.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 08/05/2019 02:40 am
Random idea:
If you want a line of starships and a launchpad, how about an old starship hull that has been carefully filled with water/mud and allowed to freeze as part of your protection? You could also selective fill some blast-facing cabins while having the elevator and some other cabins still usable if you can think of a use for a tower near the launch-site.

Additionally there could be some banners hanging off it that could catch some fragments that could otherwise bounce  around it and still hit the shielded line of ships.

Since you will be sending more to mars than bringing back, I think you will end up with a lot of such hulls on the surface. For mars missions I think you only get a few uses out of each ship. Just for the number shown in those images you probably already have at least one retired hull in addition to the first couple that are not coming back.

(edit) this would not stop some ballistic fragments sailing over the top. Better yet would be if these pillars actually dot the line of ships, and then they could also support some sort of shield from above (and I suppose from micrometeors if they are any problem on Mars)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/05/2019 04:34 am
Fair's fair. Time for me to put out some of my own ideas to get torn apart. :)

What about a simple "batting cage" system? It would need to prevent bad ricochets (eg by angling or tweaking the mesh properties), be strong enough to catch the occasional chunk of concrete, fine enough for small gravel, and weak enough so Starship can flatten it without serious damage in an off-nominal landing. And of course lightweight and easy to install.


I was merely asking... if it was possible to find a solution that allowed for a close pad.

Ack, sorry I missed this fact originally.

To survive a fully-fueled liftoff RUD, it's just gotta be underground right? A big unpressurized "NORAD" door, and the actual airlock door behind it. Backup tunnels to a safe zone.

Or as you suggest, consider the whole installation expendable in a RUD. But (I presume like yourself) I'm finding it hard to justify putting costly tank farms and pressurized habs inside the blast radius, instead of using pipes/hoses and pressurized rovers for those functions.

Once again, sorry I hurt your feelings earlier. Trying to contribute better and kinder, and in that spirit I'll give this thread a rest for the night.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/05/2019 06:57 am
Just a general note of appreciation for Lamontagne's efforts at letting us visualise what we are talking about.

Even the recently subject of criticism, the pad-de-la-muerte, it was seeing it that led to my own reaction. Talking about berms and distances in words doesn't substitute for actually seeing the relative size of that berm and the ships, tanks, and distances to buildings.



What about a simple "batting cage" system? It would need to prevent bad ricochets (eg by angling or tweaking the mesh properties), be strong enough to catch the occasional chunk of concrete, fine enough for small gravel, and weak enough so Starship can flatten it without serious damage in an off-nominal landing. And of course lightweight and easy to install.

If the debris is high-energy enough (M*V²) to cause damage to a solid structure further away, surely it's high-energy enough to tear through a lighter and much closer net?

For eg, taking the analogy literally: If you could hit a baseball with enough force to rupture a steel propane tank at, say, 100m, how heavy would the cage mesh have to be to stop that same ball at, say, 10m from the bat. Surely heavier than the walls of the tank? Even allowing for the failure of the cage to be part of the reduction in energy of the ball, the cage would still need to be painfully heavy to offer more than token resistance.

You might be able to stop debris only travelling fast enough to merely break a window, but even then, the higher-energy debris will shred the net before the lower-energy stuff even reaches it, so it wouldn't even help with that?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/05/2019 07:03 am
[edit: Moved to Martian Spaceport (https://forum.nasaspaceflight.com/index.php?topic=48732.msg1974808#msg1974808) thread.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/05/2019 07:26 am
Seems like a good argument for Mos Eisley style Docking Bays.

Even the fluffiest piece of debris will fly very far due to lack of air resistance and the lower gravity. Maximum ballistic range is v2 / g so a piece of debris travelling at Mach 1 (200m/s on Mars) would travel a whopping 10 500m or so, neglecting the minimal drag. In practice I guess 5km or less would be perfectly safe due to low odds of getting hit but I would expect a minimum of 1 500m.

For obvious reasons, I'd also expect the main settlement to be north or south of the pads.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/05/2019 03:17 pm
Fair's fair. Time for me to put out some of my own ideas to get torn apart. :)

What about a simple "batting cage" system? It would need to prevent bad ricochets (eg by angling or tweaking the mesh properties), be strong enough to catch the occasional chunk of concrete, fine enough for small gravel, and weak enough so Starship can flatten it without serious damage in an off-nominal landing. And of course lightweight and easy to install.


I was merely asking... if it was possible to find a solution that allowed for a close pad.

Ack, sorry I missed this fact originally.

To survive a fully-fueled liftoff RUD, it's just gotta be underground right? A big unpressurized "NORAD" door, and the actual airlock door behind it. Backup tunnels to a safe zone.

Or as you suggest, consider the whole installation expendable in a RUD. But (I presume like yourself) I'm finding it hard to justify putting costly tank farms and pressurized habs inside the blast radius, instead of using pipes/hoses and pressurized rovers for those functions.

Once again, sorry I hurt your feelings earlier. Trying to contribute better and kinder, and in that spirit I'll give this thread a rest for the night.
Aye, I hadn't really though about what a RUD might mean.  I thought that it was so unlikely that it didn't need to be taken into account.  I see that SpaceX has created an internal range control system for Falcon 9, in particular for when the ship is out of contact with controllers, that can decide the proper course of action in case of loss of a certain number of mission parameters.  An evolved version of this will be implemented for Starship, I guess.

I think the value of the propellant to the settlement is too great for them to afford to lose it.  So I guess there will be remote tanks, and pipelines, perhaps with small local holding tanks.
So, happily contradicting myself, I guess distance is the best safety, in this case.  I was too narrowly focused on the pad/spaceship interactions.

Berms are supposed to be a cheap solution, I guess.  How much would a screen cost, probably with advanced materials, compered to a heap of regolith?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/05/2019 03:22 pm
Seems like a good argument for Mos Eisley style Docking Bays.

Even the fluffiest piece of debris will fly very far due to lack of air resistance and the lower gravity. Maximum ballistic range is v2 / g so a piece of debris travelling at Mach 1 (200m/s on Mars) would travel a whopping 10 500m or so, neglecting the minimal drag. In practice I guess 5km or less would be perfectly safe due to low odds of getting hit but I would expect a minimum of 1 500m.

For obvious reasons, I'd also expect the main settlement to be north or south of the pads.

I agree that the pad near to the settlement is a bad option.  In particular, future expansion will put more and more infrastructure at risk if the pad is near.  As an analogy, an airport too close to a city center will be a problem, and will create problems both for the city development and the airport development.
And to look again at berms, a bit like a Vauban fortress, city development always exceeds the walls, and then they become useless.

I guess the question now would be, with a far away pad, what is the best arrangement for the tanks?  ANd that is probably already answered in pads on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 08/06/2019 03:57 am
For obvious reasons, I'd also expect the main settlement to be north or south of the pads.

This could also work well with the portions of the base that have to be surface being in one wall of east-west running canyons, with reflectors on the far canyon wall.
* Good radiation shielding.
* Decent light through less transparent material without complicated sun tracking.
* .. and fantastic shielding from shrapnel coming from one direction. Fragments would only rip up some of the foil-like reflectors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: punder on 08/07/2019 10:04 pm
Berms are supposed to be a cheap solution, I guess.  How much would a screen cost, probably with advanced materials, compered to a heap of regolith?
Coming over from the spaceport thread...

"Bulletproof" cloth, Kevlar or whatever, can be rolled very tightly (I assume; seems reasonable), so a whole bunch of it could be packed into a lander. It can be cut. It can be sewn. Holes can be patched. Fences made from it could be layered for worst-case areas--if a rock isn't stopped by the first fence, it reaches the second fence with far less energy.

Placing a fence on a conveniently situated natural hill or ridge would instantly increase the protected area, but wouldn't be absolutely necessary.

And as I noted in the other thread, it's a multipurpose material, capable of holding things in as well as keeping them out.

Would have to be formulated to survive in the Martian environment of course. But it seems like really useful stuff.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/09/2019 08:52 am
The best pad protection - which also allows a pad in close proximity to the base - is to have the base underground. That also solves the radiation problem. I'm sorry for all the claustrophobics out there, but I think the early period of Martian human settlement will resemble the early period of Earthly human settlement: we'll be cavemen.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/09/2019 08:58 am
Most of the Mars colony design proposals I've seen involve living on the surface in pressurized buildings or domes of various kinds. I'd like to discuss why I think that's impractical for the long term, and why I believe colonists will eventually need to live underground.

The Radiation Assessment Detector on the Mars Curiosity rover made detailed measurements of radiation on the surface. It found a dose of 244 millisieverts (mSv) per Earth year. The average natural background radiation in the United States is 2.6 mSv (226 mrads) per year, a little more than 1% as much.

DOE’s annual limit for radiation workers is 20 mSv, which means the surface of Mars provides about 22 times that amount.

Another source of data is NASA’s 2001 Mars Odyssey spacecraft. It measured the radiation environment from orbit around Mars, and found it to be 22 mrads per day. The conversion of millirads to millisieverts depends on the type of particles involved (x-rays vs. neutrons, for example). However, the conversion factors (dividing by between 10 and 200) put those measurements at least roughly in the same range as Curiosity. Odyssey also detected two solar storm proton events, with radiation levels of about 2,000 mrads, and other events that were up to 100 mrads.

In addition to exposure while on the surface, people will also receive additional radiation during the transit time from Earth to Mars. The dose in space is nearly three times as much as on the surface, 1.8 mSv per day. Even a short 90-day transit will put travelers beyond DOE’s safety recommendations, at 162 mSv – not including solar flares. That additional dose will make Mars residents that much more sensitive to the radiation they receive on the surface. Note that solar storms will affect people on the ground on Mars, as well as those in space.

For comparison, a 6 month stay on the International Space Station provides a dose of about 300 mSv (1.67 mSv/day).

Mars doesn’t have a magnetic field, and its atmosphere is very thin. As the numbers above indicate, unless proper radiation shielding can be provided, surface radiation is not compatible with long-term human life on Mars. Clearly, anything we can do to mitigate radiation exposure for people living on Mars will be important for their long-term health and well-being.

The most effective way to shield for radiation on Mars requires mass. To a first approximation, the more mass we can put between residents and the sources of radiation (mostly the Sun), the better.

An initial estimate of the minimum amount of mass needed for shielding is the mass of the atmosphere that’s directly above us here on Earth – 15 lbs. per square inch. Mars is farther away from the Sun than Earth by a factor of about 1.38x at perihelion. Since radiation strength decreases as a factor of R^2, that’s roughly 1.9x less radiation exposure from the Sun at Mars compared to Earth. However, that reduction is offset by the fact that Mars doesn’t have a magnetic field, which traps and/or redirects various forms of radiation near Earth. As a rough guess for this analysis, let’s say that’s another 1.9x, meaning the distance and magnetic field effects offset each other. That means the mass needed on Mars would be the same as on Earth, which is the local atmospheric pressure.

Martian regolith will provide the most readily available source of mass – the amount needed is certainly much more than we would want to bring with us from Earth (although some shielding in the spacecraft would be prudent, especially during solar storms – perhaps in the form of water).

Water on Mars will be a crucial resource. The primary sources of water, as understood today, are underground, in a type of Martian permafrost – frozen water, mixed with regolith. Extracting that water will require excavation. One approach to living underground could start with building structures in those excavated areas. Once the structures are in place, they can then be covered with the previously excavated and water-extracted regolith.

This approach is better than building shielded structures above-ground, since the sides of the excavated areas become walls, which act as additional shielding. Using excavated regolith mainly as a "roof" will also make it easier and faster to build, compared to having to also build thick walls in above-ground structures.

Based on what’s known about Martian regolith, it's reasonable to assume for the moment that it will be possible to manufacture some form of concrete and clay from available materials. Both substances require water. Clay and concrete were used thousands of years ago on Earth; the associated source materials, manufacturing and construction techniques are well-understood.

For underground structures, it should be possible to make air-tight interior walls that sit against regolith from clay alone. When more strength (or perhaps water resistance) is needed, concrete can be used.

The depth of shielding needed is based on a rough estimate of the density of the regolith of 5 grams per cc (sorry for the mixed units). At 2.54 cm/in, that’s 6.45 cm^2. At 5 gr/cc for the regolith, that’s 32.3 gr/cm for each square inch. Our target from above is 15 lbs per square inch = 6,800 g / in^2; 6800 / 32.3 = 210.5 cm = 82.3 in = 6.9 ft – round-up to 8 ft to provide a margin of safety.

It will be important to take Bremsstralung radiation into account. This is where certain high-energy particles can interact with high-Z materials and create what ends up being a more dangerous form of radiation – effectively amplifying what’s there, rather than reducing it. It’s possible to mitigate this effect by covering the top layer of shielding with a low-Z material.

In addition, it’s possible that the top few inches or even feet of regolith may be somewhat radioactive naturally, as a result of being bombarded with radiation from space over millions of years. Therefore, it may be necessary to discard that top layer, before using deeper materials to construct living areas.

I'm taking the liberty of quoting Ace's excellent posting in this this thread where we have already for very long been discussing these issues.

Just want to throw in here that living undercround can not just be done in excavated and covered trenches, but also in bored tunnels and underground spaces dug out by roadheaders.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/09/2019 09:16 am
[also plunder]

The best pad protection - which also allows a pad in close proximity to the base - is to have the base underground. That also solves the radiation problem. I'm sorry for all the claustrophobics out there, but I think the early period of Martian human settlement will resemble the early period of Earthly human settlement: we'll be cavemen.

Since you're thread-policing, there's a specific thread for launch pads (https://forum.nasaspaceflight.com/index.php?topic=48732.0) and their associated issues.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/09/2019 09:40 am
Just want to throw in here that living undercround can not just be done in excavated and covered trenches, but also in bored tunnels and underground spaces dug out by roadheaders.

Good point.

My assumption has been that early excavation would be done using simple robotic bulldozers and the like (scrape-and-scoop). However, as soon as tunnel boring machines and the like are available, the resulting spaces could certainly be used as well. In general, when it comes to radiation (particularly solar storms), the deeper, the better.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/09/2019 11:08 am
I've done extensive simulations with NASA's own radiation transport codes, which you can see in the previous pages. 2m of rock or 3m of loose regolith layered as a dome is sufficient to lower daily doses to radiation worker limits. Any water ice included (especially layered) dramatically improves the protection.

More than 6m is pointless because that's equivalent to Earth's atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/09/2019 12:12 pm
I've done extensive simulations with NASA's own radiation transport codes, which you can see in the previous pages. 2m of rock or 3m of loose regolith layered as a dome is sufficient to lower daily doses to radiation worker limits. Any water ice included (especially layered) dramatically improves the protection.

More than 6m is pointless because that's equivalent to Earth's atmosphere.

My estimate was 2.1m of regolith (2.4m with some margin), combined with a layer of low-Z material (probably water) to mitigate Bremsstralung -- so that fits nicely with your 2 to 3m number. I haven't run the numbers for the water layer, but if I had to guess, something like 0.25m seems about right.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 08/09/2019 12:40 pm
In general, when it comes to radiation (particularly solar storms), the deeper, the better.

Are you sure?

Someone correct me if I am wrong, but as far as I know, solar storms have huge radiation doses, but are also composed of rather low energy protons, which are easy to shield. Even Martian atmosphere attenuates them greatly, and a shelter on the surface solves the issue completely.

On the other hand, galactic cosmic rays, composed of high energy nuclei from outside our solar system, are the real radiation threat, either in space or on Mars. That is where the need for multiple meters of shielding comes from.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/09/2019 01:33 pm
My assumption has been that early excavation would be done using simple robotic bulldozers and the like (scrape-and-scoop). However, as soon as tunnel boring machines and the like are available, the resulting spaces could certainly be used as well. In general, when it comes to radiation (particularly solar storms), the deeper, the better.

Who knows what Elon comes up with? - But he's had a noticeable interest in tunnel boring machinery lately.

I think what will fly to Mars will be highly modular. Perhaps a bulldozer shovel, a roadheader grinder and a TBM head as different modules that will all go on the same drivetrain. Electrically driven, remotely-controlled and ultra-light, of course.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 08/09/2019 01:42 pm
I doubt TBM will be on Mars anytime soon, it is a large piece of equipment, and there is no need for Martian habitats to be long and tunnel-like. We don't use TBMs to build general underground spaces on Earth either, only tunnels. My bet is on a roadheader doing the excavations.

Then you probably need some kind of an airtight wall liner (ISRU made?), and an airlock. Lots of pressurized, radiation shielded space could be quickly created this way.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/09/2019 01:53 pm
We have the TBM and roadheader arguments every so often. In order to tunnel on Mars, you need bedrock. No-one knows what the depth to bedrock is, but it seems to be at least 30m from examining impact craters etc. Whereas cut n cover can be all done with a backhoe and some boarding. Slip some board over the excavated hole, scoop dirt over it and due to soil arching, it will be self-supporting.

Certain crater rims, hills and valleys allow access into bedrock (see lamontagne's earlier stuff) so this is a viable option for boring/roadheaders.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/09/2019 01:58 pm
I doubt TBM will be on Mars anytime soon, it is a large piece of equipment, and there is no need for Martian habitats to be long and tunnel-like. We dot use TBMs to build general underground spaces on Earth either, only tunnels. My bet is on a roadheader doing the excavations.

Then you probably need some kind of an airtight wall liner (ISRU made?), and an airlock. Lots of pressurized, radiation shielded space could be quickly created this way.
You might enjoy the design shown here.  It was derived from discussions done earlier in the thread, and I came to similar conclusions.  I do use long habitats, because I still haven't found out a good way of making nodes to connect the pressure linings of the tunnels.
https://sites.google.com/view/estepona-on-mars
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/09/2019 02:09 pm
My estimate was 2.1m of regolith (2.4m with some margin), combined with a layer of low-Z material (probably water) to mitigate Bremsstralung -- so that fits nicely with your 2 to 3m number. I haven't run the numbers for the water layer, but if I had to guess, something like 0.25m seems about right.

The water layer is not really effective on its own, it needs to be layered in 20g/cm2 thicknesses.  60/40 regolith/water is very effective, almost as efficient as pure water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/09/2019 03:08 pm
It is true that a roadheader is best suited to create interior habitable volumes, but if you want to "get somewhere", i.e. have a certain extension of your habitat, a TBM is really the answer. I suspect a roadheader will go up first and a TBM later, when the roadheader has created a proper rockface and initial conditions for a TBM to be deployed.

Mind you, it won't be a TBM looking anything like its earthly several-hundred-ton-siblings. I think it will be much lighter, easy to assemble, electric, and perhaps a brick/building block-maker at the same time, using electric sintering. Devouring bedrock at one end and spitting building blocks or even better, tunnel liner, out the other end.

It will make sense to find a location where the tunnelling can take you to ice deposits. Drill small tubes to the deposits, pump in hot air and - with gravity's help - obtain liquid water which will be stored in caves made by the roadheader.

Eventually you might combine work and leisure and end up with something ressembling the Miskolc cave baths in Hungary (this is the amazing habitats thread, after all): http://barlangfurdo.hu/en/experience-bath-cave
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 08/09/2019 04:56 pm
For obvious reasons, I'd also expect the main settlement to be north or south of the pads.
I was trying to think of why... does it have to do with reentry paths of incoming vessels being primarily east/west?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/09/2019 08:26 pm
In general, when it comes to radiation (particularly solar storms), the deeper, the better.

Are you sure?

Someone correct me if I am wrong, but as far as I know, solar storms have huge radiation doses, but are also composed of rather low energy protons, which are easy to shield. Even Martian atmosphere attenuates them greatly, and a shelter on the surface solves the issue completely.

On the other hand, galactic cosmic rays, composed of high energy nuclei from outside our solar system, are the real radiation threat, either in space or on Mars. That is where the need for multiple meters of shielding comes from.

Solar proton energy varies from one storm to the next, but in rare cases it can be as high as 100 MeV. That's strong enough to reach the surface of Earth, through both the magnetic field and the atmosphere.

It doesn't take a tremendous amount of mass to bring the radiation dose down to a tolerable level, provided the shielding includes a layer of low-Z material to help mitigate the Bremsstralung effect. When I said the deeper, the better, all I meant was if you want to drive the dose to zero, it takes a bit more.

An well-designed storm shelter in a spacecraft could be relatively thin (rough guess: 4 cm of Aluminum and 20 cm of water), since it only needs to make the total dose tolerable.

And yes, I agree about galactic cosmic rays.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TheFrizz on 08/09/2019 08:49 pm
For obvious reasons, I'd also expect the main settlement to be north or south of the pads.
I was trying to think of why... does it have to do with reentry paths of incoming vessels being primarily east/west?

I am not an expert, but I'm not so sure if this would be the case. I know the last stated SpaceX plan is to not aerocapture, but to do direct descent. But if SpaceX was doing aerocapture, capturing into an orbit with no inclination (and thus landing trajectory strictly east-west) is one of the worst possible aerocaptures because it means the Starship can only reach points near the equator.

Better to aerocapture into a somewhat polar orbit (easy with the tiniest of mid-transfer course correction) so that any destination can be reached by waiting a few orbits for the landing site to line up. If the final plan changes to aerocapture, in order to be able to receive telemtry on Earth and ensure a landing is likely to be successful before committing to descent, the landings may not reliably be strictly east west. I imagine there are possibly other reasons apart from aerocapture that might dictate non east-west landing trajectories. Not saying I know what they are going to do, but I imagine the final landing trajectory will be somewhat of a "it's not that simple" kind of thing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 08/09/2019 09:07 pm
In general, when it comes to radiation (particularly solar storms), the deeper, the better.

Are you sure?

Someone correct me if I am wrong, but as far as I know, solar storms have huge radiation doses, but are also composed of rather low energy protons, which are easy to shield. Even Martian atmosphere attenuates them greatly, and a shelter on the surface solves the issue completely.

On the other hand, galactic cosmic rays, composed of high energy nuclei from outside our solar system, are the real radiation threat, either in space or on Mars. That is where the need for multiple meters of shielding comes from.

Solar proton energy varies from one storm to the next, but in rare cases it can be as high as 100 MeV. That's strong enough to reach the surface of Earth, through both the magnetic field and the atmosphere.

It doesn't take a tremendous amount of mass to bring the radiation dose down to a tolerable level, provided the shielding includes a layer of low-Z material to help mitigate the Bremsstralung effect. When I said the deeper, the better, all I meant was if you want to drive the dose to zero, it takes a bit more.

An well-designed storm shelter in a spacecraft could be relatively thin (rough guess: 4 cm of Aluminum and 20 cm of water), since it only needs to make the total dose tolerable.

And yes, I agree about galactic cosmic rays.
I suggest that the storm shelter also doubles up as the sleeping quarters. That way the crew gain maximum protection for the greatest time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/09/2019 09:25 pm
Early inflatable under a regolith mound.

Could inflatables such as Bigelow's really be buried this simply?  Just pile on the Earth?  And am I correct in thinking that their mass would be significantly reduced, since they would not need to have as many layers as orbital ones?  If you use sand, rather than rock, to pile up on the inflatable, that would pretty much be safe against punctures?  A bit like working with some of the stronger geotextile membranes?
Title: Re: Envisioning Amazing Martian Habitats
Post by: KSHavre on 08/09/2019 09:38 pm
Early inflatable under a regolith mound.

Could inflatables such as Bigelow's really be buried this simply?  Just pile on the Earth?  And am I correct in thinking that their mass would be significantly reduced, since they would not need to have as many layers as orbital ones?  If you use sand, rather than rock, to pile up on the inflatable, that would pretty much be safe against punctures?  A bit like working with some of the stronger geotextile membranes?

I know this has been discussed before in this thread and others, but bear with me. The regolith for the mound in this drawing has to come from somehere (else), so nets out to more work. Trenching, inflating, and covering means you do not have to bring regolith from somewhere else. Plus, what would you do with the hole that excavation from elsewhere leaves behind?

For your design it just puts the connecting tunnels and 'cargo' port at the top level, and you can leave the dome as is.

If you have in your (very cool) grand design a requirement for a very large hole somewhere, like digging for bedrock so TBM can get to work; disregard this post!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/10/2019 03:54 am
I know this has been discussed before in this thread and others, but bear with me. The regolith for the mound in this drawing has to come from somehere (else), so nets out to more work. Trenching, inflating, and covering means you do not have to bring regolith from somewhere else. Plus, what would you do with the hole that excavation from elsewhere leaves behind?

That's the exact point I was trying to make a few posts earlier.

Now add to that the idea that you'd like to be able to make as many of the building materials locally as you can, rather than importing them from Earth, and you'll end up with something close to what I suggested.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 08/10/2019 07:42 am
I have an idea for an initial Martian habitat.

I am sure first several Starships landed on Mars will be expended. So dig a large depression, maybe even use a hole left after mining Martian ice. Then use a crane or something to lay a Starship on its side in the depression. Cover with 4 meters of ice and regolith for radiation shielding. Make access ports into now empty propellant tanks, too.

3000 cubic meters of pressurized, radiation shielded volume, and no need to bother with underground digging, wall liners or importing a separate airlock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/10/2019 09:44 am
Early inflatable under a regolith mound.

Could inflatables such as Bigelow's really be buried this simply?  Just pile on the Earth?  And am I correct in thinking that their mass would be significantly reduced, since they would not need to have as many layers as orbital ones?  If you use sand, rather than rock, to pile up on the inflatable, that would pretty much be safe against punctures?  A bit like working with some of the stronger geotextile membranes?

Don't see why not, but some kind of boarding would be needed in case the module deflates. Soil pressure comes in from the *sides* mostly. One change I would make: pile the regolith peak a little higher so that the middle section is more fully protected.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/10/2019 03:39 pm
Early inflatable under a regolith mound.

Could inflatables such as Bigelow's really be buried this simply?  Just pile on the Earth?  And am I correct in thinking that their mass would be significantly reduced, since they would not need to have as many layers as orbital ones?  If you use sand, rather than rock, to pile up on the inflatable, that would pretty much be safe against punctures?  A bit like working with some of the stronger geotextile membranes?

Don't see why not, but some kind of boarding would be needed in case the module deflates. Soil pressure comes in from the *sides* mostly. One change I would make: pile the regolith peak a little higher so that the middle section is more fully protected.
Peak up in the center!  Yes, I was worried it was a bit thin.
Wonder if a post installed structure inside the inflatable would be enough?  The skin will keep some strength after all, most of everywhere, even if it is torn somewhere.
My winter garage comes to mind:  It's a pretty thin layer of plastic, yet it can stand up to about 2 feet or more of very compacted snow.  Sand on Mars has about the same weight? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/10/2019 04:12 pm
Lunar dirt is as heavy as snow, Mars dirt would be comparable to say sawdust? I think reinforcement would be minor, just looking at earthworks on Earth. A PVC pipe is strong enough not to be crushed by metres of dirt overhead... internal plastic or aluminium struts should be fine, with some clever modelling and design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: punder on 08/10/2019 10:03 pm
I did a quick little Solidworks model... just a quick, rough, linear approximation (not considering the ends) of a hab shielded with Martian regolith, with and without fabric fences used as retaining walls.

Required thickness of shielding = 3m, angle of repose = 30 degrees, hab diameter = 8m, length 12m (although the length falls out for the percentage comparison).

With the fences added as shown (some construction required, pretty much negligible weight compared to regolith), the amount of regolith needed to provide the 3m of shielding around the full circumference of the hab is cut by more than a third. That might make a big difference over a large number of facilities to be shielded.

I ain't no civil engineer so maybe I'm missing something.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/11/2019 03:30 am
I did a quick little Solidworks model... just a quick, rough, linear approximation (not considering the ends) of a hab shielded with Martian regolith, with and without fabric fences used as retaining walls.

Required thickness of shielding = 3m, angle of repose = 30 degrees, hab diameter = 8m, length 12m (although the length falls out for the percentage comparison).

With the fences added as shown (some construction required, pretty much negligible weight compared to regolith), the amount of regolith needed to provide the 3m of shielding around the full circumference of the hab is cut by more than a third. That might make a big difference over a large number of facilities to be shielded.

I ain't no civil engineer so maybe I'm missing something.
Cost of the retaining walls if from Earth, vs cost of regolith, perhaps?  If the walls are made in situ (fiberglass, basalt fiber?) then they might save cost vs saving work. 
Won't the retaining walls spill out?  Do they have some perpendicular parts as well?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/11/2019 09:56 am
if you want to "get somewhere", i.e. have a certain extension of your habitat, a TBM is really the answer.

Actual TBMs are used to tunnel. Nothing else. They are very inflexible and unsuited to excavating out anything other than a fixed-diameter, reasonably straight, linear tunnel. They aren't even suited to make a branched tunnel or intersection of tunnels, not even to radiate straight tunnels from a node. TBMs are so inflexible that it's not uncommon for projects to seal the TBM underground after the project is finished, because it can't even be backed out.

I've sometimes used the term TBM as a short-hand for "rock digging system" but an actual TBM (even a Mars-adapted one) will never be used for anything except digging tunnels for roads/utilities once a colony gets big enough that it costs more to do those things in the open.

You can, of course, adapt your habitat to fit into a tunnel. But why? You're picking an unsuitable technology that needs to be adapted to Mars, to do a job it wasn't intended for (and isn't good at), and then have to adapt everything else around that unsuitable technology.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/11/2019 10:05 am
In my experience, retaining walls are always more expensive than moving earth, unless the digging undermines the foundation of something else, or causes problems elsewhere (such as preventing access).

Even if the material you create the wall out of (which doesn't have to be fabric, most retaining walls are just bricks and/or concrete) was sourced locally, it would likely be better used for something else than as a retaining wall.

A mount of dirt is usually the cheapest option. (Hell, it's the metric of cheap to which we compare other things. "As cheap as...")
Title: Re: Envisioning Amazing Martian Habitats
Post by: biosehnsucht on 08/12/2019 12:10 am
I did a quick little Solidworks model... just a quick, rough, linear approximation (not considering the ends) of a hab shielded with Martian regolith, with and without fabric fences used as retaining walls.

Required thickness of shielding = 3m, angle of repose = 30 degrees, hab diameter = 8m, length 12m (although the length falls out for the percentage comparison).

With the fences added as shown (some construction required, pretty much negligible weight compared to regolith), the amount of regolith needed to provide the 3m of shielding around the full circumference of the hab is cut by more than a third. That might make a big difference over a large number of facilities to be shielded.

I ain't no civil engineer so maybe I'm missing something.

Someone previously brought up using those off the shelf dirt bags that are used on military basis to set up walls / etc, you'd probably need to bring along some long poles or wires or something to anchor them together but seems like you could stack and fill bags to get your 1/3 savings vs building retaining walls the old fashioned way ...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/12/2019 04:26 am
I did a quick little Solidworks model... just a quick, rough, linear approximation (not considering the ends) of a hab shielded with Martian regolith, with and without fabric fences used as retaining walls.

Required thickness of shielding = 3m, angle of repose = 30 degrees, hab diameter = 8m, length 12m (although the length falls out for the percentage comparison).

With the fences added as shown (some construction required, pretty much negligible weight compared to regolith), the amount of regolith needed to provide the 3m of shielding around the full circumference of the hab is cut by more than a third. That might make a big difference over a large number of facilities to be shielded.

I ain't no civil engineer so maybe I'm missing something.

Someone previously brought up using those off the shelf dirt bags that are used on military basis to set up walls / etc, you'd probably need to bring along some long poles or wires or something to anchor them together but seems like you could stack and fill bags to get your 1/3 savings vs building retaining walls the old fashioned way ...

Agreed. AKA HESCO Bastion barrier gabions. https://en.wikipedia.org/wiki/Hesco_bastion

Hand assembly (note the helix-and-rod system for attaching gabions together):
https://www.youtube.com/watch?v=Z1RVuGImIww

Here's a version with a more automated deployment mechanism:
https://www.youtube.com/watch?v=GTZscYmBXco


Note that the bastions have very similar construction to standard reinforced earth retaining walls. Essentially they can be thought of as nothing but a quick deploying, austere version of this:
https://www.youtube.com/watch?v=0olpSN6_TCc
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/12/2019 02:24 pm
if you want to "get somewhere", i.e. have a certain extension of your habitat, a TBM is really the answer.

Actual TBMs are used to tunnel. Nothing else. They are very inflexible and unsuited to excavating out anything other than a fixed-diameter, reasonably straight, linear tunnel. They aren't even suited to make a branched tunnel or intersection of tunnels, not even to radiate straight tunnels from a node. TBMs are so inflexible that it's not uncommon for projects to seal the TBM underground after the project is finished, because it can't even be backed out.

I've sometimes used the term TBM as a short-hand for "rock digging system" but an actual TBM (even a Mars-adapted one) will never be used for anything except digging tunnels for roads/utilities once a colony gets big enough that it costs more to do those things in the open.

You can, of course, adapt your habitat to fit into a tunnel. But why? You're picking an unsuitable technology that needs to be adapted to Mars, to do a job it wasn't intended for (and isn't good at), and then have to adapt everything else around that unsuitable technology.

It seems that both Elon Musk and Gwynne Shotwell disagree with what you state here (thanks to Dave G for digging up (sic) the quotes):

I also found this quote (https://futurism.com/underground-martian-habitats-boring-company) from Elon Musk:
Quote
“You could build an entire city underground if you wanted to,” said Musk during a Q&A session at the International Space Station Research and Development (ISSR&D) Conference in July. “People are still going to want to go to the surface from time to time, but you can build a tremendous amount underground with the right boring technology on Mars.”

So we have both the CEO and president of SpaceX on record talking about boring tunnels to house people.

I think they'll also have some habitable structures on the surface to grow food and do some other things,
but it seems like people on Mars will spend most of their time in underground habitats created by boring tunnels.

Or take a Boring Company evolved TBM and a roadheader, using them to tunnel into the nearest cliff.

Gwynne Shotwell also spoke about digging tunnels to house people on Mars. Here's a link:
SpaceX exec says Elon Musk's Boring Company could dig out homes on Mars (https://www.cnet.com/news/spacex-exec-gwynne-shotwell-says-elon-musks-boring-company-could-create-homes-on-mars/)

Quote from: CNET article
Musk's side project, tunnel-digging startup the Boring Company, could one day be used to create much of the living space for that Martian colony, according to SpaceX President and COO Gwynne Shotwell.

"I think the Boring Company could be the way that we house people on Mars. We'll have to dig tunnels for folks," Shotwell told CNBC.
Title: Re: Envisioning Amazing Martian Habitats
Post by: AC in NC on 08/12/2019 02:51 pm
It seems that both Elon Musk and Gwynne Shotwell disagree with what you state here (thanks to Dave G for digging up (sic) the quotes)

The quotes are not inconsistent with his point.

He is saying TBM's are inflexible.  They are.
EM is saying "the right boring technology" and GS is saying "tunnels" (casually on the specificity spectrum) and "The Boring Company"

Neither quote says "TBM is really the answer".
Both essentially mesh with his point about "Rock Digging System".
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/12/2019 03:13 pm
In general, regarding the "surface vs. underground" debate, I think it could perhaps be a good idea to take a First Principles approach to the problem, as Elon seems fond to do, without getting stuck in legacy thinking.

Before moving into the pros and cons of both methods, I'd like to pay tribute to the free-flowing discussion in this thread over several years. I think all participants have been enlightened as to what is actually possible to build on Mars. Big geodesic domes and habs without radiation hardening have all fallen by the wayside, which is of course a bit sad but which also brings us closer to what may eventually be built in the future.

Now, a surface base will:
- Be built from structural elements primarily brought from Earth.
- Have to be protected from radiation.
- Have to incorporate all-round protection against a near vacuum.
- Have to be protected from rockets taking off and landing.
- Provide direct viewing of the outdoors, for psychological relief.

An underground base will:
- Use the Martian bedrock as its main structural element.
- Be protected from radiation.
- Be protected from the near vacuum except at entry-exit points.
- Be protected from nearby rocket take-offs and landings.
- Only provide indirect viewing (via screens) of the surface.

These are some of the main differences, outlined in broad strokes, as I see them. It would be interesting to create a really exhaustive list of pros and cons of either choice and put some estimates on the overall costs.

Of course it is also good to keep in mind that the real, future base will surely incorporate both above-ground and below-ground elements: An underground base will definitely be connected to surface solar panels. And even a surface base will have to be largely buried to be protected against radiation.

Hope this posting can stimulate further First Principles debate. No need to start the detailed base planning (except for fun!) before settling basic parameters.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/12/2019 03:24 pm
It seems that both Elon Musk and Gwynne Shotwell disagree with what you state here (thanks to Dave G for digging up (sic) the quotes)

The quotes are not inconsistent with his point.

He is saying TBM's are inflexible.  They are.
EM is saying "the right boring technology" and GS is saying "tunnels" (casually on the specificity spectrum) and "The Boring Company"

Neither quote says "TBM is really the answer".
Both essentially mesh with his point about "Rock Digging System".

TBM stands for Tunnel Boring Machine. Everybody realises that the TBMs that may be used on Mars will be very far removed from the TBMs employed on Earth up till now. That is the main reason why Elon Musk set up The Boring Company: to dramatically advance the state of the art.

However, the main reference for both is The Boring Company. That is pretty unequivocal. What they both say is that there will be TBMs. But they'll surely not look like your grandma's TBMs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/12/2019 08:04 pm
snip

Now, a surface base will:
- Be built from structural elements primarily brought from Earth.
- Have to be protected from radiation.
- Have to incorporate all-round protection against a near vacuum.
- Have to be protected from rockets taking off and landing.
- Provide direct viewing of the outdoors, for psychological relief.

An underground base will:
- Use the Martian bedrock as its main structural element.
- Be protected from radiation.
- Be protected from the near vacuum except at entry-exit points.
- Be protected from nearby rocket take-offs and landings.
- Only provide indirect viewing (via screens) of the surface.

Thanks, great perspective. I agree in all broad strokes.

Your overview suggests the most effective synthesis is a combination — mostly underground for inexpensive and secure pressurized volume, with smaller (and more expensive) above-ground glassy vegetated spaces located at entry-exit points for psychological benefit.

So it seems we have come full circle:

Quote from: /u/ElonMuskOfficial
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

https://old.reddit.com/r/spacex/comments/590wi9/comment/d94t2bv?context=1

Imo "living space" here should mostly be understood as "enjoyable public space," not so much "apartments."

Furthermore expect the glass geodesics to be almost entirely above-ground, not hemispheres. Like the example below but even more so:

(https://upload.wikimedia.org/wikipedia/commons/4/4c/Navy-Radome.jpg)

Internal glass or catwalk floors would maximize usable floor area for plant growth and human occupancy, but minimize shadows and light loss. Even just white colored floors/ceilings would help. Guy wires for wind load, supplemental lighting in places (open 24.5/7, gotta maximize that utilization!) and insulating shades drawn at night for thermal (excepting gaps for surface viewing and stargazing).

Obviously these would preferably be located in places of surpassing beauty, to maximize the psychological "bang" for the buck. In relatively featureless locations some might be positioned on a guyed mast, resembling a monopole water tower (or, for that matter, SpaceX's planned Florida control tower). This configuration is relatively inexpensive (adding "only" the pole and larger guy wires), provides a control room location with excellent situational awareness of operations, and also follows the "High Places" pattern identified by Chris Alexander et. al. in A Pattern Language.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/12/2019 10:04 pm
I definitely see a place for geodesic domes but I think they will appear quite late in the development of the base. A bit like the Cupola of the ISS: a module you add after all the necessary trusses, panels, radiators, hubs and habs are in place.

As to the difficulties of making a dome withstand near vacuum surroundings... Well, that will be a tough nut to crack! The half-dome shape is great for withstanding outside pressure. Not so much the other way round. Perhaps lots of high-strength wires criss-crossing the interior from one side to the other?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/12/2019 11:06 pm
As to the difficulties of making a dome withstand near vacuum surroundings... Well, that will be a tough nut to crack! The half-dome shape is great for withstanding outside pressure. Not so much the other way round. Perhaps lots of high-strength wires criss-crossing the interior from one side to the other?

One approach that should make above-ground domes easier to implement is to only inflate them to about 3 psi, with pure oxygen -- the same thing they did for early spacesuits.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/12/2019 11:24 pm
I definitely see a place for geodesic domes but I think they will appear quite late in the development of the base. A bit like the Cupola of the ISS: a module you add after all the necessary trusses, panels, radiators, hubs and habs are in place.

Agreed. In the mean-time, I'd expect small (Cupola-size and a bit larger) windows in "meeting lounge" areas located on the corners/penetrations of regolith-shielded structures. These multi-purpose gathering areas can be used as situation rooms if needed, eg if external cameras fail.


As to the difficulties of making a dome withstand near vacuum surroundings... Well, that will be a tough nut to crack! The half-dome shape is great for withstanding outside pressure. Not so much the other way round. Perhaps lots of high-strength wires criss-crossing the interior from one side to the other?

Geometrically speaking, running criss-crossing wires gives the same ultimate strength as distributing that same structural mass around the perimeter, ie making the dome's prefab struts thicker. The strong CFRP struts carry the whole-dome tensile loads, while the glass only carries internal atmospheric pressure loads to the edge of the pane.

I do expect that structural mass will be conserved by mounting both internal and external hardware to the high-strength dome: external surface comm antennas, perimeter observation catwalks, water shielding tanks, even whole internal floors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/13/2019 10:54 am
One approach that should make above-ground domes easier to implement is to only inflate them to about 3 psi, with pure oxygen -- the same thing they did for early spacesuits.

This has been done to death in the thread, but short answer is that this drastically increases your fire risk. See NASA's research on flammability of materials, example (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070005041.pdf).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/13/2019 11:04 am
As to the difficulties of making a dome withstand near vacuum surroundings... [...] Perhaps lots of high-strength wires criss-crossing the interior from one side to the other?

Why bother? Just complete the sphere. Same approximate framing mass.

However, for the Iceberg Base (9/10th below the surface), the "dome" is essentially just a window. Its anchor is the underground base it is budding up from. It's not really a dome, it's just the visible rounded end of whatever is buried under it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/13/2019 12:36 pm
As to the difficulties of making a dome withstand near vacuum surroundings... [...] Perhaps lots of high-strength wires criss-crossing the interior from one side to the other?

Why bother? Just complete the sphere. Same approximate framing mass.

However, for the Iceberg Base (9/10th below the surface), the "dome" is essentially just a window. Its anchor is the underground base it is budding up from. It's not really a dome, it's just the visible rounded end of whatever is buried under it.

Paul451 brings up a topic which I was just about to get to.

If the Starship lands in a region with significant subsurface ice (basically dirt-covered glaciers), as it seems to be increasingly indicated, this means that the "underground" is going to be dirty ice, which is almost as hard to drill through as rock, but of course melts quite easily and is the primary resource. Unlike a flags and footprints mission, the Starship landings are there to make a colony of (one day) a million people, so the incentive is to land it near the most abundant and easily accessible water possible - ice.

TBMs, roadheaders etc are an option but by far the easiest option that has been considered by NASA is what's called a rodwell, which is just drilling into the ice a ways and melting it to make a water-filled bulb, which is then extracted.

One Starship top-up is some 600 tonnes, so add in a bit of loss, impurities etc and some water used for other purposes and you get 1000m3 per Starship-synod. The bulb shape is good for underground structures because it's naturally strong (a dome) and sealed for a modest amount of pressure (I don't know what a 1 bar ice bulb would do though). Insulation would be required. The structure might actually just float on the melted water. Illumination could come through an overhead skylight/mirror/fibre optic system. Surface ice domes would provide radiation-safe views of the surrounds.

Alternatively, you could just pump some of the water that you've mined and use it shield conventional tin can or inflatable modules. You actually get more habitable volume this way... using the extracted water voids as habitat spaces is not very efficient although the radiation protection is superb.

https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/13/2019 01:03 pm
[rodwells]

Rodwells are cool (ha!), but it's worth remembering that they aren't permanent structures. If you don't expand them, they dig themselves down into the ice.  If you do expand them, they can only get so large before they collapse. Either way, you have to move them every few years. On Mars you might be able to extend that, lower gravity, plus some pressurisation to help carry the roof, but the issue remains, only the time-table varies.

As a water source, tapping into a buried glacier, that shouldn't be an issue (provided you build your equipment to be relocated regularly). But it's a deal breaker if you want to use the excavated volume as a habitat.

(That said, if you bring the required heat in as light instead of hot water, for example illuminate the cavity with high strength grow-lights, you might be able to turn it into an aquatic grow-chamber. Growing algae and algae-eating fish. Fairly easy to seed a new well from the old, before the old one collapses. And easy to over-harvest the fish/algae, depleting the old well before it becomes too dangerous to work and you have to withdraw the lights/pumps/plumping/etc.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 08/13/2019 02:36 pm
For obvious reasons, I'd also expect the main settlement to be north or south of the pads.
I was trying to think of why... does it have to do with reentry paths of incoming vessels being primarily east/west?

I am not an expert, but I'm not so sure if this would be the case. I know the last stated SpaceX plan is to not aerocapture, but to do direct descent. But if SpaceX was doing aerocapture, capturing into an orbit with no inclination (and thus landing trajectory strictly east-west) is one of the worst possible aerocaptures because it means the Starship can only reach points near the equator.

Better to aerocapture into a somewhat polar orbit (easy with the tiniest of mid-transfer course correction) so that any destination can be reached by waiting a few orbits for the landing site to line up. If the final plan changes to aerocapture, in order to be able to receive telemtry on Earth and ensure a landing is likely to be successful before committing to descent, the landings may not reliably be strictly east west. I imagine there are possibly other reasons apart from aerocapture that might dictate non east-west landing trajectories. Not saying I know what they are going to do, but I imagine the final landing trajectory will be somewhat of a "it's not that simple" kind of thing.
Hey! Great first post, welcome to the forums.  So that gives my suggested answer the kibosh, but we still are left with why  you want to be due N or S... any ideas?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/14/2019 12:21 am
For obvious reasons, I'd also expect the main settlement to be north or south of the pads.
I was trying to think of why... does it have to do with reentry paths of incoming vessels being primarily east/west?

I am not an expert, but I'm not so sure if this would be the case. I know the last stated SpaceX plan is to not aerocapture, but to do direct descent. But if SpaceX was doing aerocapture, capturing into an orbit with no inclination (and thus landing trajectory strictly east-west) is one of the worst possible aerocaptures because it means the Starship can only reach points near the equator.

Better to aerocapture into a somewhat polar orbit (easy with the tiniest of mid-transfer course correction) so that any destination can be reached by waiting a few orbits for the landing site to line up. If the final plan changes to aerocapture, in order to be able to receive telemtry on Earth and ensure a landing is likely to be successful before committing to descent, the landings may not reliably be strictly east west. I imagine there are possibly other reasons apart from aerocapture that might dictate non east-west landing trajectories. Not saying I know what they are going to do, but I imagine the final landing trajectory will be somewhat of a "it's not that simple" kind of thing.
Hey! Great first post, welcome to the forums.  So that gives my suggested answer the kibosh, but we still are left with why  you want to be due N or S... any ideas?

ISTM that for maximum trajectory efficiency Starship would want to aerocapture and land from a west-to-east direction, to minimize horizontal delta-v.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/14/2019 10:14 am
For obvious reasons, I'd also expect the main settlement to be north or south of the pads.
I was trying to think of why... does it have to do with reentry paths of incoming vessels being primarily east/west?

I am not an expert, but I'm not so sure if this would be the case. I know the last stated SpaceX plan is to not aerocapture, but to do direct descent. But if SpaceX was doing aerocapture, capturing into an orbit with no inclination (and thus landing trajectory strictly east-west) is one of the worst possible aerocaptures because it means the Starship can only reach points near the equator.

Better to aerocapture into a somewhat polar orbit (easy with the tiniest of mid-transfer course correction) so that any destination can be reached by waiting a few orbits for the landing site to line up. If the final plan changes to aerocapture, in order to be able to receive telemtry on Earth and ensure a landing is likely to be successful before committing to descent, the landings may not reliably be strictly east west. I imagine there are possibly other reasons apart from aerocapture that might dictate non east-west landing trajectories. Not saying I know what they are going to do, but I imagine the final landing trajectory will be somewhat of a "it's not that simple" kind of thing.
Hey! Great first post, welcome to the forums.  So that gives my suggested answer the kibosh, but we still are left with why  you want to be due N or S... any ideas?

ISTM that for maximum trajectory efficiency Starship would want to aerocapture and land from a west-to-east direction, to minimize horizontal delta-v.

Launch azimuths are typically around due East (90 degrees) of the launch site to take advantage of the Earth's (or Mars') rotation. Gravity pulls the rocket South. This is complicated by launch windows... Apollo launches had 26 degrees of leeway which gave them a 2.5+ hour window.

Coming in, there's a lot more flexibility but being able to land while coming in due East will also help because the planet's rotation means there is less braking to do.

The SpaceX video showed the Starships coming in heading due East and the colony right in the path of the launch trajectory. That strikes me as just being for artistic effect.

With fast transfers though, the landing window seems to be earlier in the day, maybe even in the night depending on how far the re-entry portion of the braking lasts, whether they skip or glide etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/18/2019 12:35 pm
An extendable and expandable habitat module.
Used in the early days, before extensive underground construction from in-situ materials.
Would have compressed air tanks in the hard section for expansion.  About  1000m3, so about 1 tonne of compressed air required.

All the interior partitions would be assembled after expansion, and stored inside the rigid part.

After expansion the habitat is buried in sand.  If pressure is lost, the rigid structure and walls create safe rooms for the crew, if the sand collapses.
In the first 3 images the shell is removed for clarity and because it would be very difficult to model!
Title: Re: Envisioning Amazing Martian Habitats
Post by: docmordrid on 08/18/2019 10:35 pm
An extendable and expandable habitat module.
Used in the early days, before extensive underground construction from in-situ materials.
>

A updated Nissen hut 😉
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/18/2019 10:50 pm
Looks great, lamontagne: just the thing needed for the initial base! I previously thought that the Starships would be a good initial habitat before underground space was created, but it probably won't be a good idea due to radiation. Or am I wrong?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/19/2019 01:28 am
Looks great, lamontagne: just the thing needed for the initial base! I previously thought that the Starships would be a good initial habitat before underground space was created, but it probably won't be a good idea due to radiation. Or am I wrong?
Musk said the ships would be used as habitats, but did not give any details. 
I think the ships could be improved a lot, radiation wise,  by pumping up water to them and having the walls designed with empty spaces for extra water, but have 0 facts.
I think the base may need an intermediate phase before they really get the underground part going.  So much depends on how workable/usable the regolith will be, if there is suitable rock nearby, etc.  So I think a surface hab than can be buried is a possibility.  A very similar design, not buried, would make a good test greenhouse.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/19/2019 01:33 am
An extendable and expandable habitat module.
Used in the early days, before extensive underground construction from in-situ materials.
>

A updated Nissen hut 😉
Absolutely. I knew them as Quonset huts but it seems to be the same idea.  It's also close to the fabric buildings used for tennis or football (soccer).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/20/2019 02:27 am
The problem with buried habitats is that they become invisible!

Mars base with buried habitats just behind the visible foreground infrastructure
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 08/21/2019 05:28 am
Maybe a light tower over each habitat.  People will, no doubt, be out at night and will need to see their way home.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/21/2019 06:07 am
Maybe a light tower over each habitat.  People will, no doubt, be out at night and will need to see their way home.

Actually a good point. You also want lighting to examine the state of the habitat exteriors, see where robots are and provide illumination for their cameras etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/21/2019 10:35 am
Maybe a light tower over each habitat.  People will, no doubt, be out at night and will need to see their way home.

Combined light tower and cell tower. An RF tower allows for more distant line-of-sight and over-the-horizon communication, and also using a suit-mounted directional antenna to orient toward the hab in the thickest dust storm.

Adding a small rotating "lighthouse" wouldn't hurt either. Long range visibility yet low power.

A stoplight indicator might show each airlock's status at a glance — red means out-of-order, yellow means currently cycling, green means go (helpful with multiple redundant airlocks). Airlock doors would likely be colored in contrasting blue, both to aid locating the door in poor visibility and to facilitate periodic dust cleaning maintenance.

Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 08/22/2019 05:51 am
One thing that impressed me in "The Martian" movie was the searchlight beacon atop the hab.  ASFAIC remember it wasn't mentioned in the book but seeing it in the movie showed what a good idea it will be to have at least one of these.

Regarding the buried hab invisibility, I was just thinking of a 5mt pole at each airlock with a floodlight or two to illuminate the area.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/22/2019 06:20 am
To make the habs visible, a simple tarp draped over them would also help.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/22/2019 08:13 am
To make the habs visible, a simple tarp draped over them would also help.

Somewhere around page 80 I suggested draping lightweight fabric over a regolith-covered hab for aesthetics. Iirc I suggested it might resemble a traditional Parisian apartment block, with the "roof" shape covering the sloped edge of the regolith shield.

But take your pick of styles/colors. Pigment isn't terribly heavy. :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: KSHavre on 08/22/2019 11:59 pm
Maybe a light tower over each habitat.  People will, no doubt, be out at night and will need to see their way home.

Combined light tower and cell tower. An RF tower allows for more distant line-of-sight and over-the-horizon communication, and also using a suit-mounted directional antenna to orient toward the hab in the thickest dust storm.

Adding a small rotating "lighthouse" wouldn't hurt either. Long range visibility yet low power.

A stoplight indicator might show each airlock's status at a glance — red means out-of-order, yellow means currently cycling, green means go (helpful with multiple redundant airlocks). Airlock doors would likely be colored in contrasting blue, both to aid locating the door in poor visibility and to facilitate periodic dust cleaning maintenance.

Where I work, most of our products use status indicator LEDs. We find ourselves trying to cover every contingency and sometimes end up with many colors, solid vs. flashing, etc. We have done User Experience studies that show fewer indicators are more effective; Users can remember what they mean! May I suggest keeping it very simple; the following indicator criteria assumes the "lighthouse" beacon exists which makes excellent sense (I am also US Sailing certified).

Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

Following the K.I.S.S. methodology, I cannot think of any other indicator light that would prove valuable in the early stages. And, if another status becomes critical, you are not adding to several other indicators. This also assumes that the airlocks are actually locked for the non-usable side of the airlock and if it is out-of-service, they do not open easily. And, there should be manual over-rides in case of extreme emergency...

* The indicators do not have to be very bright, which would be annoying as you are walking up to the airlock.
* The lighthouse strobe would lead you to the habitation modules, and airlock indicators become visible within X distance (X=no less than the distance between airlocks in a sandstorm so you can always see more than one).
* If the indicator is out, the airlock is out-of-service. If you can see the lighthouse, the hab is powered, and you should see other Airlocks. If not, try the door; you have bigger problems than an indicator light is out!
* If it is Yellow, wait.
* If it is Red, you can open the external door
* If it is Green, you can open the internal door.

These are the details that make dangerous expeditions safer and usable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DasBlinkenlight on 08/23/2019 12:51 am
Quote
Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

I would deviate from this a little.  I would suggest green means pressure is equal to the side you are on, and red means not.   So if the lock is pressurized, it means that the inside door would show green and outside show red.   Likewise if it were unpressurized, outside would be green and inside would be red.

In other words, green means "go"... you can open the door when it is green on your side, which ever side you are on.   
Title: Re: Envisioning Amazing Martian Habitats
Post by: KSHavre on 08/23/2019 01:43 am
Quote
Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

I would deviate from this a little.  I would suggest green means pressure is equal to the side you are on, and red means not.   So if the lock is pressurized, it means that the inside door would show green and outside show red.   Likewise if it were unpressurized, outside would be green and inside would be red.

In other words, green means "go"... you can open the door when it is green on your side, which ever side you are on.

Thank you, even better!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/23/2019 02:46 am
I think we can just put some lights on the Starship if we want the base to be easy to find

However, the color codes for the airlocks are a great detail.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/23/2019 03:19 am
No Light = Out of commission

I would prefer blinking red here, to readily distinguish this "marked out-of-order" state from a simple power failure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/23/2019 03:41 am
Quote
Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

I would deviate from this a little.  I would suggest green means pressure is equal to the side you are on, and red means not.   So if the lock is pressurized, it means that the inside door would show green and outside show red.   Likewise if it were unpressurized, outside would be green and inside would be red.

In other words, green means "go"... you can open the door when it is green on your side, which ever side you are on.

Minor point: don't forget about those who are red/green colorblind; color alone is an unreliable indicator.

Stoplights skirt this because the lights also have a positional component.

You might also use a large X (not safe) or O (safe), for example, and/or use vertical or left/right positioning.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/23/2019 03:44 am
Quote
Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

I would deviate from this a little.  I would suggest green means pressure is equal to the side you are on, and red means not.   So if the lock is pressurized, it means that the inside door would show green and outside show red.   Likewise if it were unpressurized, outside would be green and inside would be red.

In other words, green means "go"... you can open the door when it is green on your side, which ever side you are on.

Minor point: don't forget about those who are red/green colorblind; color alone is an unreliable indicator.

Stoplights skirt this because the lights also have a positional component.

The "green" color actually has a substantial amount of blue mixed in. This makes it easy for the colorblind to distinguish red vs green on stoplights. I assume Mars airlocks would be no different.

Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 08/23/2019 05:15 am
I agree with the traffic light layout with red indicating not available and green indicating available for access.
While cycling I'd have flashing yellow arrows pointing toward the red or green to indicate which way the lock is pumping and maybe a countdown timer toward cycle completion.  Could be useful in an emergency.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KSHavre on 08/23/2019 05:38 am
Quote
Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

I would deviate from this a little.  I would suggest green means pressure is equal to the side you are on, and red means not.   So if the lock is pressurized, it means that the inside door would show green and outside show red.   Likewise if it were unpressurized, outside would be green and inside would be red.

In other words, green means "go"... you can open the door when it is green on your side, which ever side you are on.

Minor point: don't forget about those who are red/green colorblind; color alone is an unreliable indicator.

Stoplights skirt this because the lights also have a positional component.

The "green" color actually has a substantial amount of blue mixed in. This makes it easy for the colorblind to distinguish red vs green on stoplights. I assume Mars airlocks would be no different.

I was thinking "thumbs up" and "thumbs down" iconography, but Ace already said X and O; much simpler and retro... ;-p
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/23/2019 06:10 am
Quote
Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

I would deviate from this a little.  I would suggest green means pressure is equal to the side you are on, and red means not.   So if the lock is pressurized, it means that the inside door would show green and outside show red.   Likewise if it were unpressurized, outside would be green and inside would be red.

In other words, green means "go"... you can open the door when it is green on your side, which ever side you are on.

Minor point: don't forget about those who are red/green colorblind; color alone is an unreliable indicator.

Stoplights skirt this because the lights also have a positional component.

The "green" color actually has a substantial amount of blue mixed in. This makes it easy for the colorblind to distinguish red vs green on stoplights. I assume Mars airlocks would be no different.

I was thinking "thumbs up" and "thumbs down" iconography, but Ace already said X and O; much simpler and retro... ;-p

What are X and O again?

Nevermind, the fact that I have to ask illustrates the point. ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/23/2019 07:56 am
Quote
Over each Airlock:
No Light = Out of commission
Red = No pressure (safe to enter from Mars surface)
Yellow = Changing state
Green = Habitation Pressure (safe to enter from Hab)

I would deviate from this a little.  I would suggest green means pressure is equal to the side you are on, and red means not.   So if the lock is pressurized, it means that the inside door would show green and outside show red.   Likewise if it were unpressurized, outside would be green and inside would be red.

In other words, green means "go"... you can open the door when it is green on your side, which ever side you are on.

Minor point: don't forget about those who are red/green colorblind; color alone is an unreliable indicator.

Stoplights skirt this because the lights also have a positional component.

The "green" color actually has a substantial amount of blue mixed in. This makes it easy for the colorblind to distinguish red vs green on stoplights. I assume Mars airlocks would be no different.

I was thinking "thumbs up" and "thumbs down" iconography, but Ace already said X and O; much simpler and retro... ;-p

What are X and O again?

Nevermind, the fact that I have to ask illustrates the point. ;)

Somebody's watching too much anime ;)

O is the Japanese version of a tick. But it would be good to put Chinese characters/Japanese kana up on the airlocks as well. Private Japanese citizens are already involved with DearMoon as customers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/23/2019 11:39 am
I hope you guys are not going to discuss Martian doorknobs over the next few pages...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/23/2019 12:40 pm
I hope you guys are not going to discuss Martian doorknobs over the next few pages...
Yes!  Starting the spin-off thread: https://forum.nasaspaceflight.com/index.php?topic=48872.0
Mars surface airlocks.   :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 08/23/2019 12:47 pm
An extendable and expandable habitat module.
Used in the early days, before extensive underground construction from in-situ materials.
Would have compressed air tanks in the hard section for expansion.  About  1000m3, so about 1 tonne of compressed air required.

All the interior partitions would be assembled after expansion, and stored inside the rigid part.

After expansion the habitat is buried in sand.  If pressure is lost, the rigid structure and walls create safe rooms for the crew, if the sand collapses.
In the first 3 images the shell is removed for clarity and because it would be very difficult to model!
Heh, there's a prototype of one of these in one of the buildings at NASA Langley.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 08/23/2019 12:52 pm
An extendable and expandable habitat module.
Used in the early days, before extensive underground construction from in-situ materials.
Would have compressed air tanks in the hard section for expansion.  About  1000m3, so about 1 tonne of compressed air required.

All the interior partitions would be assembled after expansion, and stored inside the rigid part.

After expansion the habitat is buried in sand.  If pressure is lost, the rigid structure and walls create safe rooms for the crew, if the sand collapses.
In the first 3 images the shell is removed for clarity and because it would be very difficult to model!
Heh, there's a prototype of one of these in one of the buildings at NASA Langley.
Really ?  Cool!  Any pictures?  Specs?
Title: Re: Envisioning Amazing Martian Habitats
Post by: OhYeah on 08/23/2019 02:06 pm
I have a question. Is there/has there been a separate thread for farming on Mars or should it be discussed in this thread?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Yggdrasill on 08/23/2019 02:08 pm
Fits better in this thread: https://forum.nasaspaceflight.com/index.php?topic=35877.0
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/23/2019 02:08 pm
I have a question. Is there/has there been a separate thread for farming on Mars or should it be discussed in this thread?


Yup. Here you go:

https://forum.nasaspaceflight.com/index.php?topic=35877.0

Of course, if you want to post your designs for farming modules etc you can put them here too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 08/23/2019 04:47 pm
I just love that "Das blinkenlight" suggested... solid lights.

Inop and light burned out and powerfailed are the same thing to my way of thinking. If the light isn't on, don't trust the lock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/24/2019 03:51 am
I just love that "Das blinkenlight" suggested... solid lights.

Inop and light burned out and powerfailed are the same thing to my way of thinking. If the light isn't on, don't trust the lock.

But inoperative indicates that it's a known condition to base operations. It's sufficiently dissimilar that it deserves a distinct signal imo.

In Japan they also have regular traffic lights. They're even more blue actually.


Doorknobs (and in general, the best design for interior air sealing isolation doors) seems quite pertinent. Ideally doors could be closed from either side despite differential pressure (eg in a leak situation). This favors rotating or sliding designs over conventional hinges. Ideally the latch could be operated manually, so a lever or wheel would be the "doorknob." I predict Elon will insist on convenient sexy motorized doors ala Model X, with manual backup.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CuddlyRocket on 08/26/2019 02:49 am
Minor point: don't forget about those who are red/green colorblind; color alone is an unreliable indicator.

There are people who only have monochromatic vision and see the world in black and white. (There's also blue/yellow colourblindness, but that's possibly less relevant here.) Although you might not expect people with such visual impairments to be selected for initial crews, any design should look to the future.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/26/2019 06:54 am
An extendable and expandable habitat module.
Used in the early days, before extensive underground construction from in-situ materials.
All the interior partitions would be assembled after expansion, and stored inside the rigid part.
Heh, there's a prototype of one of these in one of the buildings at NASA Langley.
Really ?  Cool!  Any pictures?  Specs?

I assume he means the "planetary surface habitat and airlock unit (https://www.nasa.gov/centers/langley/news/researchernews/rn_inflatable-lunar-hab.html)":

(https://www.nasa.gov/centers/langley/images/content/170068main_influnarhab01-1024.jpg) (https://www.nasa.gov/centers/langley/images/content/170068main_influnarhab01-1024.jpg)

But there's also the "X-HAB" (50+ page PDF (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100017479.pdf)):

(https://www.researchgate.net/profile/Sandra_Haeuplik-Meusburger/publication/254255494/figure/fig7/AS:284422759829512@1444823078751/Deployment-Testing-of-the-X-Hab-Lunar-Habitat-at-NASA-LaRC-credit-NASA-ILC-Dover.png) (https://www.researchgate.net/profile/Sandra_Haeuplik-Meusburger/publication/254255494/figure/fig7/AS:284422759829512@1444823078751/Deployment-Testing-of-the-X-Hab-Lunar-Habitat-at-NASA-LaRC-credit-NASA-ILC-Dover.png)

Both from ILC Dover, both via LaRC.

["X-Hab" was also the name of a NASA student design contest. Don't know if the Langley thing spun off from that, or is just someone not researching their acronyms.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/26/2019 07:47 am
A look inside Sierra Nevada's inflatable module for the moon gateway. It has the same diameter and orientation as lamontagne's buried hab, so gives us a real-world impression of the available space inside. What struck me was just how transparent the urethane bladder actually is. Even with only a very limited amount of light leaking through (and that from the exterior warehouse lighting), it created the impression of a light, airy space. I wonder if something similar could be done. Water shielding through transparent external bags (much like the revised Mars Ice House) would make quite the difference.

https://www.space.com/sierra-nevada-inflatable-habitat-moon-gateway.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/26/2019 08:09 am
What struck me was just how transparent the urethane bladder actually is.

Same with ILC's previous beastie:

(https://www.nasa.gov/sites/default/files/styles/1920x1080_autoletterbox/public/images/188818main_iotw-090907-1050.jpg?itok=CVixZebS) (https://www.nasa.gov/sites/default/files/styles/1920x1080_autoletterbox/public/images/188818main_iotw-090907-1050.jpg?itok=CVixZebS)

Interestingly, this one was apparently intended to specifically test (amongst other things) the puncture "self healing" properties of the bladder.
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 08/26/2019 09:56 am
I think an awesome use for ISRU manufactured and scrap materials would be for colony architecture.  Artistic facades as seques would allow colonist input and promote artisan endeavors.

Note the projected flames onto the airlock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 08/27/2019 08:15 pm
that's kinda trippy, TripD. not sure that projected flames on a safety critical component are the best look tho.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/28/2019 08:35 am
I love the urethane bladder structures and similar ideas.

They do make me wonder, though, whether certain shapes might be easier than others to uniformly cover with radiation shielding, in the form of 2 to 3m of regolith. I'm imagining a bulldozer of some kind, for example, pushing regolith up to the edges and dumping more on top.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/28/2019 08:56 am
They do make me wonder, though, whether certain shapes might be easier than others to uniformly cover with radiation shielding, in the form of 2 to 3m of regolith. I'm imagining a bulldozer of some kind, for example, pushing regolith up to the edges and dumping more on top.

Yeah, but the easiest shapes to drive over (or up onto) are the hardest to pressurise.

Another tick in favour of at least partial burial. Dig a hole, put the rounded bottom of the hab module in the hole, now you have a "dome" to drive up onto.

(That said, I'm also partial to an unpressurised gap betwixt pressure vessel and dirt-shield, wide enough walk down, wide enough to patch that pressure vessel wall. This means a compressive arch separate from the tensile pressure vessel.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/28/2019 09:16 am
They do make me wonder, though, whether certain shapes might be easier than others to uniformly cover with radiation shielding, in the form of 2 to 3m of regolith. I'm imagining a bulldozer of some kind, for example, pushing regolith up to the edges and dumping more on top.

Yeah, but the easiest shapes to drive over (or up onto) are the hardest to pressurise.

Another tick in favour of at least partial burial. Dig a hole, put the rounded bottom of the hab module in the hole, now you have a "dome" to drive up onto.

(That said, I'm also partial to an unpressurised gap betwixt pressure vessel and dirt-shield, wide enough walk down, wide enough to patch that pressure vessel wall. This means a compressive arch separate from the tensile pressure vessel.)

Well, there'll be a honking great hole excavated underneath each Starship. Inflate habs directly from your Starship boot packages and the overhead is shielded by 85 tonnes of Starship. Fill a tank with liquid CO2 for more radiation shielding. Push some dirt berms up to improve the side shielding.

Ugly AF...

And now here's something interesting. CO2 ice (when crystalline) is crystal clear. Might make for some interesting polar habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/28/2019 09:38 am
Yeah, but the easiest shapes to drive over (or up onto) are the hardest to pressurise.

I wonder if that's still true if regolith or perhaps clay provided some structural support (clay seems to be readily available). Inflate first to low pressure to get the basic form in place, partly cover, increase pressure, and repeat. Maybe?

Another tick in favour of at least partial burial. Dig a hole, put the rounded bottom of the hab module in the hole, now you have a "dome" to drive up onto.

I'm a big fan of buried structures, as I've said earlier here. The point I keep trying to make is that big holes will almost certainly be dug in the process of obtaining water, so why not also use them for other purposes, including habitats.

(That said, I'm also partial to an unpressurised gap betwixt pressure vessel and dirt-shield, wide enough walk down, wide enough to patch that pressure vessel wall. This means a compressive arch separate from the tensile pressure vessel.)

Is there a reason why you don't think they should be patched from the inside? I would think patches applied on the high-pressure side would be more reliable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/28/2019 09:48 am
Well, there'll be a honking great hole excavated underneath each Starship. Inflate habs directly from your Starship boot packages and the overhead is shielded by 85 tonnes of Starship. Fill a tank with liquid CO2 for more radiation shielding. Push some dirt berms up to improve the side shielding.

Ugly AF...

As something quick (and temporary), I like it.

And now here's something interesting. CO2 ice (when crystalline) is crystal clear. Might make for some interesting polar habitats.

Didn't know that. All dry ice I've ever seen was opaque. I sure wouldn't want to live (or ask others to live) in a place that had natural frozen CO2 outside, though. Yuck.

I still like my idea of a giant pool of liquid water with a glass roof and glass floor, where people could hang out or perhaps live underneath. It would provide fully radiation-shielded access to natural daylight, among other things.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/28/2019 10:19 am
I'm pleasantly surprised at the shielding effectiveness of CO2 ice. Starts at 40g/cm2 for 100gm/cm2 of shielding. Looks like it cuts the surface dose by half with no problems (halve the dose rate due to the planet surface). That would be a slab ~60cm thick.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/28/2019 04:47 pm
The point I keep trying to make is that big holes will almost certainly be dug in the process of obtaining water, so why not also use them for other purposes, including habitats.

So you're the reason I keep having to refute this bad idea! ;) The old "build your house at the bottom of a strip mine" canard. This is one of those ideas that seems good in theory, but is almost criminally unworkable in practice.


Why not you ask? Several reasons: space, time, opportunity cost, and geology.

Space: the shape of a water mining hole is quite unlikely to match very well the shape of the hab to be buried. If a substantial amount of additional backfilling or excavation is needed, you exceed the amount of excavation (and cost) over burying an above-ground structure. No, the extra shielding on the sides is not worth the extra cost.

Time: the mine is unlikely to be decommissioned at the exact same time as a new habitat needs to be built. The economics decision points for those two events are not the same.

Opportunity cost: if you "solve" the time problem by trading off between the two schedules, you're going to decommission your mine unnaturally early, and so leave unmined water "on the table," hurting the economics of your mining operation. This is not a "sexy looking" cost like the hab burying cost you're trying to reduce (and it's worth remembering that that's the only claimed advantage of your proposal), but it's a large cost nonetheless.

Geology: the rock that's suitable for building a habitat on top of is unlikely to be the same as the geology suitable for establishing a water mining operation. Heat leaking from the habitat could destabilize the permafrost and lead to catastrophic differential settling.

For all the same reasons as above (and more), here on Earth we don't build underground parking garages at the bottom of decommissioned coal strip mines.

I won't say it will never happen on Mars, but such a construction technique will be the overwhelming exception, not the overwhelming rule. Being so rare it won't really move the needle on Martian construction costs, so we still need to develop a construction approach that's economical without the "free" (read: expensive) mining pit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/28/2019 10:21 pm
The point I keep trying to make is that big holes will almost certainly be dug in the process of obtaining water, so why not also use them for other purposes, including habitats.
So you're the reason I keep having to refute this bad idea! ;) The old "build your house at the bottom of a strip mine" canard. This is one of those ideas that seems good in theory, but is almost criminally unworkable in practice.

What I'm imagining sounds very different than what you've described.

My assumptions:

-- Water will be found over very wide areas, within a few meters of the surface (which is what remote sensing data indicates).
-- Mining could be done in the size and shape needed for habitats. It wouldn't be a question of trying to fit habs into huge and oddly shaped strip mines; it would be digging holes specifically sized-and-shaped for habs, extracting water permafrost as you go.
-- If the mining areas are dug to a relatively shallow depth, there's no need to decommission anything. When you reach the desired depth, just move along in a horizontal direction.
-- On the geology front, sub-surface water permafrost will be extremely hard. I've suggested keeping it heat-insulated from the habs by using a thick layer of clay, which is known to be available on Mars.

While it's true that we don't build garages at the bottom of decommissioned coal strip mines, we do build below-ground basements all the time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/28/2019 10:53 pm
They do make me wonder, though, whether certain shapes might be easier than others to uniformly cover with radiation shielding, in the form of 2 to 3m of regolith. I'm imagining a bulldozer of some kind, for example, pushing regolith up to the edges and dumping more on top.

Yeah, but the easiest shapes to drive over (or up onto) are the hardest to pressurise.

I'm sorry, I'm afraid I don't follow. What do you mean by that?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/28/2019 11:05 pm
The point I keep trying to make is that big holes will almost certainly be dug in the process of obtaining water, so why not also use them for other purposes, including habitats.
So you're the reason I keep having to refute this bad idea! ;) The old "build your house at the bottom of a strip mine" canard. This is one of those ideas that seems good in theory, but is almost criminally unworkable in practice.

What I'm imagining sounds very different than what you've described.

My assumptions:

-- Water will be found over very wide areas, within a few meters of the surface (which is what remote sensing data indicates).

And there will nonetheless be areas of more concentrated water, and there the ice mines will be placed. Doing anything else is more costly. You're proposing to undo 5,000 years of mining economics (ie "dig where the best ore is").

-- Mining could be done in the size and shape needed for habitats. It wouldn't be a question of trying to fit habs into huge and oddly shaped strip mines; it would be digging holes specifically sized-and-shaped for habs, extracting water permafrost as you go.

Damn, and I anticipated this response too, and I almost pre-addressed this rebuttal. Mea culpa.

Basically the problem is the same as the opportunity cost problem. Now you're constraining your mine configuration to the shape of the hab, which results in higher mine operation costs than if you just let minimum cost determine the shape of the mine.

You're replacing a visible sexy cost (burying the habs) with a hidden unsexy cost (inefficient mine operations), nothing more.

-- If the mining areas are dug to a relatively shallow depth, there's no need to decommission anything. When you reach the desired depth, just move along in a horizontal direction.

Again, this is not how that economic decision is made in an actual mine. Replacing the regular cost-optimizing logic with this suboptimal logic determined by hab constraints will (say it with me!) increase the costs of the mine.

-- On the geology front, sub-surface water permafrost will be extremely hard. I've suggested keeping it heat-insulated from the habs by using a thick layer of clay, which is known to be available on Mars.

An added cost, versus choosing a site with less problematic geology (eg bedrock). This "cost saving" measure is getting awfully expensive.

While it's true that we don't build garages at the bottom of decommissioned coal strip mines, we do build below-ground basements all the time.

I'm not arguing against basements, I'm pointing out that they're not typically built in old mines. That's the exception not the rule.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 08/28/2019 11:24 pm
The point I keep trying to make is that big holes will almost certainly be dug in the process of obtaining water, so why not also use them for other purposes, including habitats.
So you're the reason I keep having to refute this bad idea! ;)
Probably me too. I have brought up this a couple of times.
Here is a link on some uses of old quarries: http://mentalfloss.com/article/76571/15-adaptive-re-uses-old-mines

Most of your points I could dismiss. It really does come down to your geology point and if you are right (which I suspect you are) then perhaps everyone should take heed. The notion of a base on a flat featureless plain anywhere may simply be wrong. I think in your plan you need two distinct geologies right next door. The hard dry rock to build your city next to the water rich geology that provides its lifeblood. This might be rare like seams of ore or oil wells. Presumably the plan is that by the time that oil well dries up you have enough infrastructure to keep shipping in the city's life-blood from ever further away. It would not be far if you are building essentially on the boundary of the frozen oceans or into a canyon wall.

This is why my recent thoughts had gone away from simply exploiting quarries to something a bit more expansive. I had imagined colonising the frozen oceans.. or the bottoms of canyons many kilometers wide that may also have very high water content below ten meters.

This does have the problem of the ground subsiding, especially when you have much heavier rock on top of frozen water. I actually want to exploit the waste heat to keep growing the body of water covered under an insulating layer that is lighter than water. This sort of colony has to be built already with buoyancy in mind, with continual controlled subsidence at the boundary far away from the pressurised portions of the town. Definitely a lot of engineering problems to work through. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 08/28/2019 11:57 pm
And there will nonetheless be areas of more concentrated water, and there the ice mines will be placed. Doing anything else is more costly. You're proposing to undo 5,000 years of mining economics (ie "dig where the best ore is").

My sense of what's "economical" on Mars sounds like it may be a lot different than yours. If "ore" is readily available a few meters beneath your feet pretty much everywhere on the planet, that seems very different to me than typical mining on Earth, and proximity seems more important than ore quality. It strikes me as closer to mining permafrost in Alaska than copper in Arizona.

Having said that, you may well be right. I hope mission planners will at least consider the possibility of reducing overall time, effort and cost by building underground. If they do and it ends up being better / faster / easier / cheaper to build and provide radiation shielding at ground level as you've suggested, I'm completely OK with that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/29/2019 07:16 am
especially when you have much heavier rock on top of frozen water.

I don't think that's a thing. Any geological process that can form rock will squeeze out the water.

You might have layers of dry rock on top of an aquifer, but an aquifer is water within the pours and cracks of either porous or fractured rock, and that water seeped in after the rock layers formed. Your melt-water colony idea doesn't work there. Similarly, you can have hydrated minerals, but those are minerals, chemically bonded water, bone dry.

I might be wrong, obviously, but I believe the whole theory of buried glaciers is cumulative loose regolith on top.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/29/2019 07:55 am
If you want a hole or depression, there are plenty of those on Mars for free. They're called craters.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/29/2019 11:43 am
If you want a hole or depression, there are plenty of those on Mars for free. They're called craters.

As I've said before, we don't "want a hole". The hole isn't important.

The argument is: "since you are already digging X amount of material and leaving a hole Y metres deep, you might as well use that material you are digging out to bury the habs you are going to be adding anyway." If you aren't digging X amount of material, the point of the argument goes away even if you can find another Y metre hole.

[Exception: Lava tubes and similar covered caves.]



However, craters are fairly shallow for their width. They aren't "holes", in any practical sense.

The bulk are 1:15 to 1:25. So you aren't gaining much depth. For most activities, being in a crater won't be much different to not. Small craters aren't any more useful than any random ridges and dips on the surface, and large craters are not much different to a wide broken plain at the base of shallow foot-hills.

(There are rare exceptions (IIRC, THEMIS once spotted a 500m wide crater that was over 400m deep), but, again, the issue isn't a burning desire for Mars holes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/29/2019 12:02 pm
Apology in advance: Very long post is very long.


tl;dr - Optimising a location for a water-mine creates opportunity costs everywhere else. Optimising for a hab's location creates opportunity costs everywhere else. Separating the two, so you can find each one an optimal site, creates opportunity costs everywhere else. Therefore talking about the "opportunity costs" for one activity in isolation isn't a valid objection.




The old "build your house at the bottom of a strip mine" canard. This is one of those ideas that seems good in theory, but is almost criminally unworkable in practice.
You're replacing a visible sexy cost (burying the habs) with a hidden unsexy cost (inefficient mine operations), nothing more.

Your reasoning focuses excessively on treating each activity as if it must be optimised in isolation. But that creates its own opportunity costs. In early colonies, nothing will be optimally sited, nor optimally equipped, nor optimally performed. Every activity will be hamstrung by the other requirements. You therefore can't argue against one activity reducing the efficiency of another, because, well, that's going to be the dominant way everything works.

It seems like you want to invoke modern best practices, as done on an industrialised planet with 7 billion people. That's a bad model (criminally bad, you might say) for a fresh colony on a new planet, with limited access to the fruits of the original planet, with inevitably inappropriate and/or sub-optimal technology, inevitably inappropriate and/or sub-optimal methods, and probably with severe labour limits. (Or at least, specialised labour limits. (See bottom of post.))

This applies even to basic equipment: every specialised machine that allows optimised mining is a generalised machine not available for other needs. Ditto every dedicated long-distance transport required for a distributed, optimised settlement. But have generalised, multi-purpose machines and every task is less efficient and/or more restricted by using those machines; have a concentrated settlement, and it's sub-optimal for either power or ISRU or, most likely, both.

And yet, for a long time, each bad-for-everything-but-good-enough choice will be the best option: concentrated settlements, limited travel, multi-purpose machines. Hell, for awhile they'll be the only options, simply because we don't know how to do better because we don't know what is better.

So if shallow pits or trenches exist because of water mining, yes we'll stick habs in them. If spoil from water-mining exists, we'll use it for radiation shielding instead of more mass-efficient shielding. Will it be optimal? No. But "optimal" isn't on the table.

The surface of Mars isn't suitable for life. You can't reasonably compare to the economic case of building homes in a mine-site on Earth, where the surface is (generally) the most optimal place for us to live. (Although even on Earth, if the surface isn't optimal for life, we sometimes build underground. Eg, Coober Pedy, Naours, Petra, Guanajuato city, and Kaymakli and similar Turkish sites, etc. Often exploiting old mines, aqueducts, or in modern cities, subways. So it's not like this thread is the first time someone's said "Hey, since we've already dug this big hole...")

Instead of centuries-optimised, best-practice 21st century, a better model is when groups from early agrarian civilisation moved into new, remote areas. While our technology level is greater, it is not especially suited to Mars, therefore our trade-offs are at the equivalent level of late stone-age or early bronze-age colonies. (Even 15th century European colonisation is too well developed for a reasonable comparison to early Mars colonies.) Every technological advantage we have over primitive colonies is countered by the lack of Earth's bounty: no air, no water, no wild animals, no fish, no trees, etc.

Like primitive colonies, travel will be limited and local, slow and costly; labour is limited and resource hungry; understanding of the new environment is limited and costly to acquire; technology and practices are mal-adapted; resources have to be painfully hand-acquired from local sources; and site choice is restricted by lack of access, knowledge, and competing needs which themselves aren't fully understood.



We don't actually know how we'll "mine" water yet. There seem to be buried glaciers, they might even be at low enough latitude for reasonable power & thermal requirements. Or there might be shallow broad areas with mixed water/regolith. And that layer could start a few centimetres below the surface or a few metres, and it could extend a few metres down, or hundreds. Or there might be something closer to an aquifer, either hyper-saline and liquid, or reasonably fresh but frozen; where one means drilling and pumping and desal, the other might mean deep shaft mining.

We don't know what is the best option, or even what is actually available. (Same with food production. There's no good Earth analogies, so we throw bad analogies at each other.)

However, the argument for buried (or half-buried) habs follows from a particular expectation for the optimal form of water mining, not the other way around. It's "this is what the mining will look like, therefore this is the site (and equipment) available to the habitats". KelvinZero's melt-water colony idea is based on the same reasoning, but assumes the most economic "water mining" will be either a scaled up version of Rodwells or where digging into a glacier/ocean resembles deep mining into rock but with melty chambers.

In both cases, the direction of reasoning is "this is the type of mining I expect, therefore it lends itself to this kind of habitation, because the requirements of mining will dominate the requirements of habitation, so we might as well roll with it". (In KZero's case, "heat from your colony will melt the ice under it anyway...")



Although we don't know for sure which type of water-mining will be best (or possible), there are some reasonable top-level assumptions we can make, IMO, at least for early settlements:

The largest task by land area will be power production.
Largest task by energy consumption and scale of equipment, propellant production.
By resource acquisition, water.
By pressurised volume, agriculture.

In spite of the many unknowns, the potential areas for variation to this list are limited:
If space-rated nukes become common and cheap, power production will take up less area but perhaps more shipping mass. Likewise if the ice layer is really shallow but also thin, then shallow scraping might be the largest activity by area in addition to the largest ISRU resource activity. I'm assuming CO2 is ignorably easy to acquire, if not, throw it on the list. Vat food production might reduce the volume requirements of agriculture, but I suspect it would have a resource burden not visible in current examples on Earth, so swings'n'roundabouts.

Those four activities will therefore be the main focus of optimisation, and optimisations will almost exclusively trade between only those four tasks. Everything else will be sub-optimal, simply because there won't be enough of it for the economics of optimisation to matter. You aren't going to spend half your spare materials and most of your spare labour reducing power consumption of something that uses 1% of your power. Or 0.1% of your water use. Or 10% of your pressurised volume. You are going to focus on the areas of greatest return-on-investment.

And for that reason, you'll note that habitats don't even appear on my list. IMO, people, living areas, and the resources to support them are a small part of the requirements for everything else; hence will be way down the list of "things you should optimise for". That means you will choose your hab site by your major resource needs (ie, water), with that limited only by power needs (ie, latitude). You will not have an optimised hab location hundreds of kilometres away from your water-mine, hundreds of kilometres away from your bauxite mine, dozens of kilometres away from your solar farm, etc etc.

Going further: for the first few settlements, anything more than an hour's drive away doesn't exist for the purposes of power/resources/agriculture and habitat locations. Perhaps even nothing beyond 1hr EVA walking distance.

If there's a better site for a resource, even just a few tens of kilometres away from your existing settlement, you won't access it from that existing settlement, you will site your next new settlement there. An entire settlement. You don't just teleop, you don't ship in your labourers every day via hyperloop or road-train. You build the next whole settlement, with habs, main power, the entire ag volumes, etc, at that site.

It will be a long time before you have stand-alone mines and farms at even modest distance from a settlement. And a long, long time before you can work over the kind of distances to remote sites that we routinely do for mining or agriculture on Earth.



Because I've been down this path before, I'll anticipate one objection, Re: shortages of specialised labour, or labour in general.

A common response is "Musk wants a million people on Mars, therefore no labour shortages". But planning on quickly adding a million people doesn't actually help. The higher the number of new colonists arriving every synod, the more colonists must be narrowly focused on expanding existing facilities in anticipation, and the less can be focused on optimisation. Hence, rapid expansion just leads to optimising for expansion, so you end up with lots of copies of things, but each copy full of inefficiencies. The colony simply won't have time to develop well. OTOH, slower expansion gives you more time to optimise designs and activities, but fewer people to spare in doing so.

[Is there an optimal rate of expansion to optimise both the expansion and the optimisation? Or... words to that effect.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/29/2019 12:14 pm
That previous comment was an objection to the broad assumptions behind your complaints, this is the more pedantic stuff on each point. Obviously the entire previous post is also my response to each point... but this is already two long, too long posts:

Space: the shape of a water mining hole is quite unlikely to match very well the shape of the hab to be buried. If a substantial amount of additional backfilling or excavation is needed, you exceed the amount of excavation (and cost) over burying an above-ground structure.

Assumes you have to back-fill up to the height of the mine. Traditional reuse of strip mines doesn't. There's no reason to assume the depth of regolith cover would be any greater than regolith covered above-ground habs. (It might be, since earth-works are fairly cheap, once the material is nicely dug up and in piles. But it doesn't have to be.)

Hell, there's also no reason to assume the excavation will be any lower than the height of the hab. It may well be that the most optimised extraction keeps the excavation shallow purely because of a lack of specialised mining machines, possibly shallower than the height of the standard hab modules.

Time: the mine is unlikely to be decommissioned at the exact same time as a new habitat needs to be built. The economics decision points for those two events are not the same.

Each settlement will need to be fairly self-contained, making enough water for their own ISRU propellant production. Water mining will therefore likely exceed habitat volume requirements by orders of magnitude. So whether strip-mining or something similar, you'll always have more previous mined area or volume than habitat demand.

Obviously, if water extraction doesn't require excavation, then this model is largely irrelevant. So either your objection doesn't matter... or your objection doesn't matter.

Geology: the rock that's suitable for building a habitat on top of is unlikely to be the same as the geology suitable for establishing a water mining operation. Heat leaking from the habitat could destabilize the permafrost and lead to catastrophic differential settling.

You simply won't have the resources to optimise both. Water extraction will be a dominant activity, so habitat location and requirements will be sub-optimal and need to adapt to the geology of the water-mine.

For all the same reasons as above (and more), here on Earth we don't build underground parking garages at the bottom of decommissioned coal strip mines.

But even here, we routinely compromise build-efficiency because of site requirements. And we compromise site selection because of resource availability. This has been the case throughout history. And the same will be true on Mars, only moreso.

For examples, our cities have grown out of early settlements, and are typically terribly located for "building a city". Unsuitable geology, unsuitable climate, freakin' volcanoes and floods and earthquakes and storms. Oh, and they end up spreading out over the best farmland. But moving the city is more expensive than just accepting the limits of history.

And there will nonetheless be areas of more concentrated water, and there the ice mines will be placed.

Then that's where the whole settlement will be. "Doing anything else is more costly."

Basically the problem is the same as the opportunity cost problem. Now you're constraining your mine configuration to the shape of the hab, which results in higher mine operation costs than if you just let minimum cost determine the shape of the mine.

Neither you nor Aces are right. A major, perhaps primary, "shape" limit will be the equipment available. Depending on the nature of the water resource, I suspect shallow, fairly linear excavation will dominate because of that. That's already fairly optimised for plonking down habs in the holes, and the equipment already optimised for back-filling from spoil.

But the requirements of solar will be a much greater constraint on water-mining than habitats. It will push you to lower latitudes, but also simply take up more land area, making mining ops more costly by forcing you to either work around the solar arrays or to constantly relocate them.

On the geology front, sub-surface water permafrost will be extremely hard. I've suggested keeping it heat-insulated from the habs by using a thick layer of clay, which is known to be available on Mars.
An added cost, versus choosing a site with less problematic geology (eg bedrock).

Exposed bedrock right next to a site with concentrated water? Doubtful. Which means you are scattering your available resources over a wide area, making people and equipment less available for other purposes, requiring more duplication and redundancies that don't aid general reliability.

"This 'cost saving' measure is getting awfully expensive."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 08/29/2019 02:29 pm
...
...
The old "build your house at the bottom of a strip mine" canard. This is one of those ideas that seems good in theory, but is almost criminally unworkable in practice.


Why not you ask? Several reasons: space, time, opportunity cost, and geology.

Space: the shape of a water mining hole is quite unlikely to match very well the shape of the hab to be buried. If a substantial amount of additional backfilling or excavation is needed, you exceed the amount of excavation (and cost) over burying an above-ground structure. No, the extra shielding on the sides is not worth the extra cost.

Time: the mine is unlikely to be decommissioned at the exact same time as a new habitat needs to be built. The economics decision points for those two events are not the same.

Opportunity cost: if you "solve" the time problem by trading off between the two schedules, you're going to decommission your mine unnaturally early, and so leave unmined water "on the table," hurting the economics of your mining operation. This is not a "sexy looking" cost like the hab burying cost you're trying to reduce (and it's worth remembering that that's the only claimed advantage of your proposal), but it's a large cost nonetheless.

Geology: the rock that's suitable for building a habitat on top of is unlikely to be the same as the geology suitable for establishing a water mining operation. Heat leaking from the habitat could destabilize the permafrost and lead to catastrophic differential settling.

For all the same reasons as above (and more), here on Earth we don't build underground parking garages at the bottom of decommissioned coal strip mines.

I won't say it will never happen on Mars, but such a construction technique will be the overwhelming exception, not the overwhelming rule. Being so rare it won't really move the needle on Martian construction costs, so we still need to develop a construction approach that's economical without the "free" (read: expensive) mining pit.
I like the way you summarized your points in an easy-to-read list.

OTOH, I may disagree with the underlying assumption that water mining will create holes in the ground or tunnels. We require water at mid latitude and will likely find it at shallow depth over a broad area. So the likely mining method for early settlement would be strip mining.

A second reason for strip mining is that loaders and mechanical shovels will likely be needed to prepare landing sites, solar panel sites and rudimentary roads. They could serve the additional purpose of mining near-surface water.

In the instance of surface mining, it becomes more feasible to exploit surface trenches as habitat sites and to utilize mining waste regolith to cover them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 08/29/2019 04:05 pm
Excerpt from Paul451 above:
"Although we don't know for sure which type of water-mining will be best (or possible), there are some reasonable top-level assumptions we can make, IMO, at least for early settlements:

The largest task by land area will be power production.
Largest task by energy consumption and scale of equipment, propellant production.
By resource acquisition, water.
By pressurised volume, agriculture.

In spite of the many unknowns, the potential areas for variation to this list are limited:
If space-rated nukes become common and cheap, power production will take up less area but perhaps more shipping mass. Likewise if the ice layer is really shallow but also thin, then shallow scraping might be the largest activity by area in addition to the largest ISRU resource activity. I'm assuming CO2 is ignorably easy to acquire, if not, throw it on the list. Vat food production might reduce the volume requirements of agriculture, but I suspect it would have a resource burden not visible in current examples on Earth, so swings'n'roundabouts.

Those four activities will therefore be the main focus of optimisation, and optimisations will almost exclusively trade between only those four tasks. Everything else will be sub-optimal, simply because there won't be enough of it for the economics of optimisation to matter. You aren't going to spend half your spare materials and most of your spare labour reducing power consumption of something that uses 1% of your power. Or 0.1% of your water use. Or 10% of your pressurised volume. You are going to focus on the areas of greatest return-on-investment.

And for that reason, you'll note that habitats don't even appear on my list. IMO, people, living areas, and the resources to support them are a small part of the requirements for everything else; hence will be way down the list of "things you should optimise for". That means you will choose your hab site by your major resource needs (ie, water), with that limited only by power needs (ie, latitude). You will not have an optimised hab location hundreds of kilometres away from your water-mine, hundreds of kilometres away from your bauxite mine, dozens of kilometres away from your solar farm, etc etc.

Going further: for the first few settlements, anything more than an hour's drive away doesn't exist for the purposes of power/resources/agriculture and habitat locations. Perhaps even nothing beyond 1hr EVA walking distance.

If there's a better site for a resource, even just a few tens of kilometres away from your existing settlement, you won't access it from that existing settlement, you will site your next new settlement there. An entire settlement. You don't just teleop, you don't ship in your labourers every day via hyperloop or road-train. You build the next whole settlement, with habs, main power, the entire ag volumes, etc, at that site.

It will be a long time before you have stand-alone mines and farms at even modest distance from a settlement. And a long, long time before you can work over the kind of distances to remote sites that we routinely do for mining or agriculture on Earth.”


Paul451, I recently posted a type of habitat that is compatible with your views of early settlement. It is basically a  buried cylinder with enhancements; it  could be located anywhere a human dwelling is needed quickly.

https://forum.nasaspaceflight.com/index.php?topic=41427.2260

I had in mind reusing large pressurized cargo modules as habitats, but now that Mr. Musk has stated that early-landed Starships may themselves be employed as surface habs, my approach seems even more relevant. For example, cargo SS could be laid in horizontal position as the habitat cylinder and a blow torch/welder used to combine cargo bay, LOX tank and CH4 tank into one long housing unit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/30/2019 04:43 pm
The point I keep trying to make is that big holes will almost certainly be dug in the process of obtaining water, so why not also use them for other purposes, including habitats.
So you're the reason I keep having to refute this bad idea! ;)
Probably me too. I have brought up this a couple of times.
Here is a link on some uses of old quarries: http://mentalfloss.com/article/76571/15-adaptive-re-uses-old-mines

Your link illustrates my point beautifully. 15 examples comprising a few hundred sites, out of hundreds of thousands of mine sites and many millions of underground structures. "The overwhelming exception, not the overwhelming rule." How is this even up for debate?

Most of your points I could dismiss.

No partial credit for hypothetical rebuttals. ;)

It really does come down to your geology point and if you are right (which I suspect you are) then perhaps everyone should take heed. The notion of a base on a flat featureless plain anywhere may simply be wrong. I think in your plan you need two distinct geologies right next door. The hard dry rock to build your city next to the water rich geology that provides its lifeblood. This might be rare like seams of ore or oil wells. Presumably the plan is that by the time that oil well dries up you have enough infrastructure to keep shipping in the city's life-blood from ever further away. It would not be far if you are building essentially on the boundary of the frozen oceans or into a canyon wall.

I think you're onto something.

It has long been observed in ecology that boundaries between biomes are more productive and diverse than the interiors (for mostly obvious reasons, such as more diverse resource availability). Look at the shore, or the forest edge, or the boundaries between fresh and salt water, or the continental shelf edge. At the most fundamental level we ourselves are terrestrial organisms, inhabiting and constructing artifacts in a thin layer at the boundary between the air and the earth (and drawing resources from both; on Earth both "sky cities" and "mole cities" would be more costly to build and operate).

I actually want to exploit the waste heat to keep growing the body of water covered under an insulating layer that is lighter than water. This sort of colony has to be built already with buoyancy in mind, with continual controlled subsidence at the boundary far away from the pressurised portions of the town. Definitely a lot of engineering problems to work through. :)

So you mean a floating / underwater city? Just so long as you name it Crazy Town (located centrally in the State of Madness, naturally).  :o

Seriously though, the answer to that engineering problem is "don't do that."

If you want to move heat around (say from a hab to an ice melting site) that's easy: pipe around some CO2 refrigerant. Lay down a grid of heat transfer tubing and cover the whole thing with an insulating blanket (optionally after exposing the ice to boost thermal transfer efficiency). These systems have non-zero cost and mass, but nothing compared to designing your entire city upside-down and backwards.

It's elegant, but what we really want is effectiveness. See Akin.

Also, will liquid water even persist at Mars atmospheric pressure? You might just be sublimating the ice away (which would work actually if you captured the water vapor, and this would solve the perchlorate problem too).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/31/2019 09:56 pm
I know there is very little water vapour (0,03%) in the Martian atmosphere, but perhaps this kind of technology could still be useful:
https://news.berkeley.edu/2019/08/27/water-harvester-makes-it-easy-to-quench-your-thirst-in-the-desert/

- There is seemingly more water vapor in the northern polar region in the early summer...

- Also, perhaps such a "harvester" could work in unison with other methods to concentrate water vapor.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 09/01/2019 03:26 am
especially when you have much heavier rock on top of frozen water.
I might be wrong, obviously, but I believe the whole theory of buried glaciers is cumulative loose regolith on top.
Yeah that is all I meant by rock. The material itself whose relevant property is that it is denser than water and won't remain above it long if the water ceases to be rock hard. Rubble, dust. I expect a lot of hydrated minerals so it might a sort of concrete like or sandstone like material?

It might just be dry dust and rocks I guess. That would be the most convenient. Then it would be a series of continual small collapses. What is most problematic would be big slabs that grow to extend tens of meters before suddenly collapsing.

If it all collapses immediately then all you would need it to begin with a cone shaped hole with the bottom in ice-heavy material. You use ISRU to spit out some sort of lighter than water thermal insulation, eg a couple of meters of fist-sized plastic bags with water and an air bubble or perhaps something more like foam rubber or aerogel. If the layer on top were just rubble and dust it would be very predictable, dictated by its angle of repose. I suspect it is more like sand stone with rubble of all sorts of sizes including some massive boulders.

By doing all your industrial activity here, all waste heat gets exploited to continue melting the ice so that most of your ISRU is just handling two easily pumped materials: silty water and CO2 atmosphere. Also some nitrogen etc so you at least have the CHON elements.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 09/01/2019 09:17 am
I know there is very little water vapour (0,03%) in the Martian atmosphere, but perhaps this kind of technology could still be useful:
https://news.berkeley.edu/2019/08/27/water-harvester-makes-it-easy-to-quench-your-thirst-in-the-desert/

- There is seemingly more water vapor in the northern polar region in the early summer...

- Also, perhaps such a "harvester" could work in unison with other methods to concentrate water vapor.

IIRC, the Curiosity Rover found that water ice often forms on the ground overnight. When the ground heats up a little in the morning, the ice evaporates, causing close to 100% humidity. The atmospheric pressure doesn't change, so the total amount of water in the atmosphere is still small. Even so, it may not be difficult to harvest -- maybe a harvester would only run in the mornings, for example, when the humidity is high.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 09/05/2019 05:16 pm
especially when you have much heavier rock on top of frozen water.
I might be wrong, obviously, but I believe the whole theory of buried glaciers is cumulative loose regolith on top.
Yeah that is all I meant by rock. The material itself whose relevant property is that it is denser than water and won't remain above it long if the water ceases to be rock hard. Rubble, dust. I expect a lot of hydrated minerals so it might a sort of concrete like or sandstone like material?

It might just be dry dust and rocks I guess. That would be the most convenient. Then it would be a series of continual small collapses. What is most problematic would be big slabs that grow to extend tens of meters before suddenly collapsing.

If it all collapses immediately then all you would need it to begin with a cone shaped hole with the bottom in ice-heavy material. You use ISRU to spit out some sort of lighter than water thermal insulation, eg a couple of meters of fist-sized plastic bags with water and an air bubble or perhaps something more like foam rubber or aerogel. If the layer on top were just rubble and dust it would be very predictable, dictated by its angle of repose. I suspect it is more like sand stone with rubble of all sorts of sizes including some massive boulders.

By doing all your industrial activity here, all waste heat gets exploited to continue melting the ice so that most of your ISRU is just handling two easily pumped materials: silty water and CO2 atmosphere. Also some nitrogen etc so you at least have the CHON elements.

rocks that are heavier than water will sink into the ice of a glacier over time here on Earth. The situation on Mars is more complex but I doubt the ice will be free from rock debris
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 09/05/2019 11:14 pm
rocks that are heavier than water will sink into the ice of a glacier over time here on Earth. The situation on Mars is more complex but I doubt the ice will be free from rock debris
For sure. One of the reasons I assumed you get a rock layer on top is that rock and ice are all mixed up.. then when the ice evaporates from the top you end up with like a 10 meter thick layer of rubble from all the bits left behind when the ice evaporates.. but the stuff beneath would still be ice with lots of rock mixed in.
Another explanation for the surface rock (non-ice) layer could be dust blowing over. That might be far more significant in the supposed "frozen oceans" as opposed to glaciers which carry rocks down with them. That could create a pretty pure separation of rock and ice.. but I assumed with glaciers and canyon floors there would be a lot of rock mixed in. In any case the idea does require a location with a suitably high ice content that it will actually settle and separate when the ice becomes liquid.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/06/2019 07:07 am
And there will nonetheless be areas of more concentrated water, and there the ice mines will be placed. Doing anything else is more costly. You're proposing to undo 5,000 years of mining economics (ie "dig where the best ore is").

My sense of what's "economical" on Mars sounds like it may be a lot different than yours. If "ore" is readily available a few meters beneath your feet pretty much everywhere on the planet, that seems very different to me than typical mining on Earth, and proximity seems more important than ore quality. It strikes me as closer to mining permafrost in Alaska than copper in Arizona.

Aluminum is also common in surface minerals on Earth. Nevertheless we have bauxite mines.

The same with water. A glacier with >80% water is a much higher "ore quality" than the ubiquitous subsurface regolith at ~5% water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 09/06/2019 08:18 am
rocks that are heavier than water will sink into the ice of a glacier over time here on Earth. The situation on Mars is more complex but I doubt the ice will be free from rock debris
For sure. One of the reasons I assumed you get a rock layer on top is that rock and ice are all mixed up.. then when the ice evaporates from the top you end up with like a 10 meter thick layer of rubble from all the bits left behind when the ice evaporates.. but the stuff beneath would still be ice with lots of rock mixed in.
Another explanation for the surface rock (non-ice) layer could be dust blowing over. That might be far more significant in the supposed "frozen oceans" as opposed to glaciers which carry rocks down with them. That could create a pretty pure separation of rock and ice.. but I assumed with glaciers and canyon floors there would be a lot of rock mixed in. In any case the idea does require a location with a suitably high ice content that it will actually settle and separate when the ice becomes liquid.

There is also a sublimation water cycle at work. Ice will condense as frost in pore spaces below the surface wherever the temperature is lowest. This doesn't happen on Earth. This is why Phoenix just scratched the surface and found water ice under the soil. The overburden essentially provides insulation and pressure for the ice below.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 09/06/2019 09:34 am
Aluminum is also common in surface minerals on Earth. Nevertheless we have bauxite mines.

The same with water. A glacier with >80% water is a much higher "ore quality" than the ubiquitous subsurface regolith at ~5% water.

Of course.

The question is, if you have to drive 10km and excavate 100m down to reach a glacier with 80% water, is that going to be better than walking 10m and digging 2m down for 5%? Eventually, perhaps. In the early days, though, I doubt it.

The details do depend on the local terrain. With my mission planner hat on, I would guess 10km distance might add an order of magnitude to the cost and effort of mining water and getting it back to the base, and 100m depth could add another order of magnitude. (Not to mention the time and effort required to find the glacier in the first place). So, if it was more like 0.5% vs. 80%, then sure, plan accordingly and go for the distant stuff.

FWIW, I think they can do better than 5%. Data from Mars Odyssey shows areas near 40 deg N with around 10%.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 09/06/2019 09:52 am
Aluminum is also common in surface minerals on Earth. Nevertheless we have bauxite mines.

The same with water. A glacier with >80% water is a much higher "ore quality" than the ubiquitous subsurface regolith at ~5% water.

Of course.

The question is, if you have to drive 10km and excavate 100m down to reach a glacier with 80% water, is that going to be better than walking 10m and digging 2m down for 5%? Eventually, perhaps. In the early days, though, I doubt it.

The details do depend on the local terrain. With my mission planner hat on, I would guess 10km distance might add an order of magnitude to the cost and effort of mining water and getting it back to the base, and 100m depth could add another order of magnitude. (Not to mention the time and effort required to find the glacier in the first place). So, if it was more like 0.5% vs. 80%, then sure, plan accordingly and go for the distant stuff.

FWIW, I think they can do better than 5%. Data from Mars Odyssey shows areas near 40 deg N with around 10%.


We already know that SpaceX is looking at Aracadia Planitia for a Starship landing site. That's because there's a fresh icy impact crater, indicating that (amongst many, many other things) that there is abundant glacial ice beneath the surface at depths of 3-5m.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 09/06/2019 10:27 am
We already know that SpaceX is looking at Aracadia Planitia for a Starship landing site. That's because there's a fresh icy impact crater, indicating that (amongst many, many other things) that there is abundant glacial ice beneath the surface at depths of 3-5m.

Right.

Arcadia Planitia is located at about 47N 176W, which is solidly in the ~10% region on the Mars Odyssey map. Hopefully, the glacial ice is readily accessible, the water content is much higher than shown, and they will end up landing close enough to it to be able to use it.

My point wasn't that high-water-content "ore" isn't a good thing. Rather, I'm just trying to say that I don't think it's a good idea to travel a long way to get it on early missions; that digging right near your base where you also don't have to be concerned with depletion will almost always be better. With a carefully chosen site, better still.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/09/2019 03:39 am
We already know that SpaceX is looking at Aracadia Planitia for a Starship landing site. That's because there's a fresh icy impact crater, indicating that (amongst many, many other things) that there is abundant glacial ice beneath the surface at depths of 3-5m.

Right.

Arcadia Planitia is located at about 47N 176W, which is solidly in the ~10% region on the Mars Odyssey map. Hopefully, the glacial ice is readily accessible, the water content is much higher than shown, and they will end up landing close enough to it to be able to use it.

My point wasn't that high-water-content "ore" isn't a good thing. Rather, I'm just trying to say that I don't think it's a good idea to travel a long way to get it on early missions; that digging right near your base where you also don't have to be concerned with depletion will almost always be better. With a carefully chosen site, better still.

My point is, we won't need to travel far. It's not an either-or decision, you can do both.

There's an entire planet to choose from. All you need is an appropriate geological boundary (for instance, exposed bedrock next to a glacier). To suppose this is impossible to find across an entire world is to beg the question.

Remember, 10% water vs 90% water means you're moving roughly 8x the amount of raw material. Excavation is very costly, so this is to be avoided. Having this "chaff" also means you need to expend far more heat to melt/evaporate the water out, which is not cheap either. And the oven (or whatever similar system) needs more volumetric capacity. These large incremental costs mean it's not worth it to mine the dry regolith for water.

No shallow water mining trenches, sorry guys. Making the mine an order of magnitude more costly isn't worth it if the only advantage is (possibly) to shorten a dirt road+pipeline.

All the arguments for putting habs in old mines presume that the typical mine site will be "used up" quickly and abandoned, but this is another unrealistic assumption. Again I don't assert that such mine-cum-underground-habs are impossible, just that they will be rare.

So far I've seen no good reason to favor old mines sites over any other hab location. All the rationales are either insignificant (topological radiation shielding), implausible (machines optimized for costly "dirt mining" trenches), or don't actually favor choosing ex-mines over any other convenient plot of land ("because it is there").

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/09/2019 12:17 pm
Apology in advance: Very long post is very long.

[lots of words]

You are reacting to a bunch of points I never made.

Obviously there are engineering trade-offs, and balancing those trades is the very method of finding the optimum. I'm talking about the global optimum, but you seem to have interpreted my words to mean some weird local (subsystem-level) optimum. That is not what I meant at all. If you re-read my post with the correct meaning of "optimal" in mind, you'll see the same points still apply.

As for your suggestion that we return to Bronze Age methods of project planning, I don't even have to refute that, do I?
Title: Re: Envisioning Amazing Martian Habitats
Post by: BZHSpace on 09/10/2019 08:36 am
I saw your works and enjoy them, I'm in architecture school so I will make a concept of a Mars habitat/city that I will show on this thread. Maybe on the begining of January/February. My concept will be a propostion of a single module, and how differents module could built a city (auto-sufficient city).

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 09/10/2019 12:48 pm
I saw your works and enjoy them, I'm in architecture school so I will make a concept of a Mars habitat/city that I will show on this thread. Maybe on the begining of January/February. My concept will be a propostion of a single module, and how differents module could built a city (auto-sufficient city).



Looking forward to it!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 09/15/2019 03:05 am
I recently ran into the video below, and couldn't help thinking about possible similarities between building in the Arctic and building on Mars -- things like excavation and construction techniques when you're living on top of a glacier, extreme environmental conditions, harvesting drinking water, expedition-type living conditions, and so on. Even though this took place 60 years ago, and the tech has improved tremendously, I still found it pretty interesting.

https://www.youtube.com/watch?v=-DPQ15EgyTY
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/06/2019 08:26 pm
From the Starship update, 2019-09-29:

https://youtu.be/sOpMrVnjYeY?t=4906

----------

Q: Are you going to bring a Boring Machine to the Moon or Mars?

Elon Musk: I think that would be a good idea because you could just make as much room as you want underground and you protect it from radiation and everything, and you could probably use the materials for building. And you need to find ice and dirt anyway, so why not, totally.

----------

....I am not going to say "I told you so".... but, anyway, I told you so!  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/07/2019 05:15 am
And last year, Starship was going to be made of cutting-edge carbon fibre...
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 10/07/2019 06:37 am
And last year, Starship was going to be made of cutting-edge carbon fibre...
You know.. I have heard that basalt is stronger than steel in some applications and also not bad with temperature... :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/07/2019 09:43 am
And last year, Starship was going to be made of cutting-edge carbon fibre...

Yes, thank God that SpaceX follows first principles and objective criteria when making their choices. Those same first principles and objective criteria that lead to tunnelling being chosen for Mars :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/07/2019 12:18 pm
Regarding "told you so" and "first principles and objective criteria..."

I was impressed by how off-the-cuff Elon's answer was (not in the transcript, but in the verbatim answer). It stuck me as a "sure why not?" answer (as if he had been asked "will there be fried chicken on Mars?"), not a "you know, I've had my engineers look into this matter real closely, and..." answer.

If this was the first time Musk was seriously contemplating it, I think this puts to bed any notions that TBC was all about ulterior Mars motives when first founded (a mold which some tragically prefer to shoehorn all of Musk's companies into).

By all indications Musk has given the idea little more thought than the ~5 seconds of brainstorming we saw on-screen.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/08/2019 12:53 am
Those same first principles and objective criteria that lead to tunnelling being chosen for Mars

Except that tunnelling is worse than any other form of excavation. Except for the special case where you want a linear road or pipe but can't access the surface due to existing infrastructure or mountains. Any other structure (not a road/pipe) and/or any other circumstance (where you can dig down), tunnelling doesn't make sense.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/08/2019 01:19 pm
Those same first principles and objective criteria that lead to tunnelling being chosen for Mars

Except that tunnelling is worse than any other form of excavation. Except for the special case where you want a linear road or pipe but can't access the surface due to existing infrastructure or mountains. Any other structure (not a road/pipe) and/or any other circumstance (where you can dig down), tunnelling doesn't make sense.

With current tunneling machines.

Its possible the improvements that Boring co. are doing to the machine this could change.
What do they have:
Prufrock
Linestorm

Not sure which is which.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/08/2019 01:56 pm
Those same first principles and objective criteria that lead to tunnelling being chosen for Mars

Except that tunnelling is worse than any other form of excavation. Except for the special case where you want a linear road or pipe but can't access the surface due to existing infrastructure or mountains. Any other structure (not a road/pipe) and/or any other circumstance (where you can dig down), tunnelling doesn't make sense.

A tunnel in rock provides a pressure resistant volume. Anything open and covered with regolith needs a pressure vessel. One that can carry the overhead burden as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KSHavre on 10/08/2019 02:44 pm
Those same first principles and objective criteria that lead to tunnelling being chosen for Mars

Except that tunnelling is worse than any other form of excavation. Except for the special case where you want a linear road or pipe but can't access the surface due to existing infrastructure or mountains. Any other structure (not a road/pipe) and/or any other circumstance (where you can dig down), tunnelling doesn't make sense.

A tunnel in rock provides a pressure resistant volume. Anything open and covered with regolith needs a pressure vessel. One that can carry the overhead burden as well.

IMHO everything that Elon invests in helps him develop and improve the technologies required to build his city on Mars. I remember this same argument regarding Starlink. A frequent L2 contributor posited that the business was only to make money for ITS, and not the exact correct method for Mars. I also remember someone from SpaceX posting (paraphrase) 'You would think I was crazy if I told you everything we are working on for Mars'. So whether you think it is the right thing to do, Elon is developing key basic technologies that can be made cheap and reliable. By finding uses here, and asking us to buy lots, he can perfect and scale production; making lots of small ones, easy to transport and replace even if they do break:

*The most efficient, and dry cell (safest) batteries. - survive dust storms
*Very high torque, reliable DC motors - everything that needs to move
*A communications network - no need to bury or string wires for communication
*A tunneling or digging machine that makes building blocks - see his quote above
*Solar panels that can also be use as an outer layer of a hab (roof tiles)
*Feel free to add to my list

His answer to the Boring Machine sounded like his answer to using Tesla motors and batteries in Starship; all I heard was "No duh!"
Title: Re: Envisioning Amazing Martian Habitats
Post by: Steve D on 10/08/2019 03:45 pm
When I think of tunneling on Mars I dont think of living in the tunnels themselves. I see a grid of tunnels and where they intersect use roadheaders to dig out chambers where the structures are built. Large chambers where multi story levels ring the walls and large open courtyards in the middle. Well lit with plants growing all around.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/08/2019 06:43 pm
Regarding "told you so" and "first principles and objective criteria..."

I was impressed by how off-the-cuff Elon's answer was (not in the transcript, but in the verbatim answer). It stuck me as a "sure why not?" answer (as if he had been asked "will there be fried chicken on Mars?"), not a "you know, I've had my engineers look into this matter real closely, and..." answer.

If this was the first time Musk was seriously contemplating it, I think this puts to bed any notions that TBC was all about ulterior Mars motives when first founded (a mold which some tragically prefer to shoehorn all of Musk's companies into).

By all indications Musk has given the idea little more thought than the ~5 seconds of brainstorming we saw on-screen.

I believe you're wrong, I think that is just the way he talks: very informally. For sure you cannot conclude anythin about his plans from the way he replied to the question. Rather you can conclude something from the actual content of the statements: by just taking them at face value instead of twisting the sense of what he said.

BTW, I think you mean "mould" and not "mold"  ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/08/2019 06:46 pm
Those same first principles and objective criteria that lead to tunnelling being chosen for Mars

Except that tunnelling is worse than any other form of excavation. Except for the special case where you want a linear road or pipe but can't access the surface due to existing infrastructure or mountains. Any other structure (not a road/pipe) and/or any other circumstance (where you can dig down), tunnelling doesn't make sense.

Maybe here on Earth but not on Mars where your interior space needs to be both a pressure vessel and radiation proof.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/09/2019 02:50 am
Regarding "told you so" and "first principles and objective criteria..."

I was impressed by how off-the-cuff Elon's answer was (not in the transcript, but in the verbatim answer). It stuck me as a "sure why not?" answer (as if he had been asked "will there be fried chicken on Mars?"), not a "you know, I've had my engineers look into this matter real closely, and..." answer.

If this was the first time Musk was seriously contemplating it, I think this puts to bed any notions that TBC was all about ulterior Mars motives when first founded (a mold which some tragically prefer to shoehorn all of Musk's companies into).

By all indications Musk has given the idea little more thought than the ~5 seconds of brainstorming we saw on-screen.

I believe you're wrong, I think that is just the way he talks: very informally. For sure you cannot conclude anythin about his plans from the way he replied to the question. Rather you can conclude something from the actual content of the statements: by just taking them at face value instead of twisting the sense of what he said.

Let's look at the content:

and you could probably use the materials for building

So above-ground structures are being assumed as well. Nothing in the content of his answer says that any serious engineering decision-making has happened either way. Just that underground structures have some advantages. So do above-ground structures btw, that's why it's called a trade-off. ;)

And I disagree that we can't find anything from the way Musk answers. He was essentially talking himself into it in real-time on stage. So I agree that it's an "informal" answer, not a glimpse at some unseen engineering analysis.

Also notice that nothing in his answer favors TBMs over other types of tunneling technology. Obviously the first step is a design study (or at least a survey of COTS tunneling technologies), but this was conspicuously absent from Musk's answer.

BTW, I think you mean "mould" and not "mold"  ;-)

Why not both? While I'm mixing metaphors I might as well mix homophones, too. ;D

Now you've got me imagining pressure vessels supported in tension by fungal hyphae...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/09/2019 03:00 am
Those same first principles and objective criteria that lead to tunnelling being chosen for Mars

Except that tunnelling is worse than any other form of excavation. Except for the special case where you want a linear road or pipe but can't access the surface due to existing infrastructure or mountains. Any other structure (not a road/pipe) and/or any other circumstance (where you can dig down), tunnelling doesn't make sense.

Maybe here on Earth but not on Mars where your interior space needs to be both a pressure vessel and radiation proof.

Regular non-TBM mining tunnels could hold pressure just fine (if you seal the entrance, ie the same as a TBM tunnel), and the overburden depth is plenty to protect from radiation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/09/2019 05:22 am
Regular non-TBM mining tunnels could hold pressure just fine (if you seal the entrance, ie the same as a TBM tunnel)...

Most martian sedimentary rock has extremely low uniaxial compressive strength, so "roadheader" tunnels wouldn't be sound.  A quick look at Mt. Sharp room-and-pillar tunneling (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859) quantified the problem, roughly.

With very rare exception (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1613904#msg1613904), if you wanted hab tunnels, you'd need basalt TBMs.  And that's very challenging, very slow work.

MW immersion heaters can melt ice with speed orders of magnitude faster than the speed of TBMs in basalt, and heaters are orders of magnitude lighter than TBMs.

Q:  Is SpaceX planning to melt "Mars Base Alpha" out of the ice?

The thickness of ice deposits at the selected site might indicate their intent:

- If ice is < 5 m thick, it could be adequate for water supply, but inadequate for melt-out hab space.

- If ice is > 50 m thick, it would be adequate not only for multistory hab space, but also for a pressurized spaceport (https://forum.nasaspaceflight.com/index.php?topic=48732.msg1989734#msg1989734).

It's interesting that SpaceX is currently looking at sites closer to 40 N than 30 N.  Crater ice deposits extend to ~ 30 N.  It seems likely that ice sufficient for water supply can be found near 30 N, a latitude desirable for winter sunlight.  But SpaceX is looking further north, where ice deposits might be thicker.  Maybe they want to be sure to locate a site with > 50 m ice thickness, for melt-out excavation of a very ambitious space.

Quote
SpaceX is eyeing these 9 places on Mars for landing its first Starship rocket missions (https://www.businessinsider.com/spacex-starship-mars-landing-sites-map-hirise-2019-9)

(https://image.businessinsider.com/5d6cda2b2e22af6c0642f773?width=600&format=jpeg&auto=webp)

An elevation map of Mars showing the nine candidate landing sites SpaceX is considering for its first Martian voyages of Starship. NASA/USGS/ESA/DLR/FU Berlin (G. Neukum) via Google Earth Pro; Business Insider.

Mean crater ice base depth in Arcadia Planitia is given as 51 m in Bramson et al. 2015. 

Refs

Bramson, A. M., Byrne, S., Putzig, N. E., Sutton, S., Plaut, J. J., Brothers, T. C., & Holt, J. W. (2015). Widespread excess ice in Arcadia Planitia, Mars. (https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2015GL064844) Geophysical Research Letters, 42(16), 6566-6574.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ChrisPhoenix on 10/09/2019 09:12 am

A tunnel in rock provides a pressure resistant volume. Anything open and covered with regolith needs a pressure vessel. One that can carry the overhead burden as well.

If the pressure vessel is flexible, then the internal pressure can carry the overhead burden. 33 kPa at Mars gravity will support a few meters of dirt - enough for decent UV and ionizing radiation shielding (and thermal (and micrometeorite, though that's more important on the Moon)). No need for Bigelow-type multi-layer construction, or even space-suit level engineering.

Wrap a few microns of Mylar in a fabric bag, and wrap that in a cargo net. Pressurize to 5 PSI, and then throw dirt on top of it.

In Martian gravity and atmosphere, you should be able to literally throw dirt where you want it - no need to transport it - just use something like a cross between a stump grinder and a snow thrower.

With internal bracing, like an air mattress, you can build a wide range of habitat shapes.

Since it's flexible until inflated, it packs small. You could have a nice big comfy safe habitat within a week of landing your first ship.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 10/09/2019 10:07 am
Regular non-TBM mining tunnels could hold pressure just fine (if you seal the entrance, ie the same as a TBM tunnel)...

Most martian sedimentary rock has extremely low uniaxial compressive strength, so "roadheader" tunnels wouldn't be sound.  A quick look at Mt. Sharp room-and-pillar tunneling (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859) quantified the problem, roughly.

With very rare exception (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1613904#msg1613904), if you wanted hab tunnels, you'd need basalt TBMs.  And that's very challenging, very slow work.

MW immersion heaters can melt ice with speed orders of magnitude faster than the speed of TBMs in basalt, and heaters are orders of magnitude lighter than TBMs.

Q:  Is SpaceX planning to melt "Mars Base Alpha" out of the ice?

The thickness of ice deposits at the selected site might indicate their intent:

- If ice is < 5 m thick, it could be adequate for water supply, but inadequate for melt-out hab space.

- If ice is > 50 m thick, it would be adequate not only for multistory hab space, but also for a pressurized spaceport (https://forum.nasaspaceflight.com/index.php?topic=48732.msg1989734#msg1989734).

It's interesting that SpaceX is currently looking at sites closer to 40 N than 30 N.  Crater ice deposits extend to ~ 30 N.  It seems likely that ice sufficient for water supply can be found near 30 N, a latitude desirable for winter sunlight.  But SpaceX is looking further north, where ice deposits might be thicker.  Maybe they want to be sure to locate a site with > 50 m ice thickness, for melt-out excavation of a very ambitious space.

Quote
SpaceX is eyeing these 9 places on Mars for landing its first Starship rocket missions (https://www.businessinsider.com/spacex-starship-mars-landing-sites-map-hirise-2019-9)

(https://image.businessinsider.com/5d6cda2b2e22af6c0642f773?width=600&format=jpeg&auto=webp)

An elevation map of Mars showing the nine candidate landing sites SpaceX is considering for its first Martian voyages of Starship. NASA/USGS/ESA/DLR/FU Berlin (G. Neukum) via Google Earth Pro; Business Insider.

Mean crater ice base depth in Arcadia Planitia is given as 51 m in Bramson et al. 2015. 

Refs

Bramson, A. M., Byrne, S., Putzig, N. E., Sutton, S., Plaut, J. J., Brothers, T. C., & Holt, J. W. (2015). Widespread excess ice in Arcadia Planitia, Mars. (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2015GL064844) Geophysical Research Letters, 42(16), 6566-6574.

I think they will need to characterise the ice in detail before any attempt is made to build a habitat in it as there are too many unknowns. Are we talking pure ice? Or is it more likely to be a dirty mix of ice dust and rock? To what extent is the ice fractured with crevases? Are methane cathrates present anywhere and how stabel are they?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/09/2019 01:02 pm
Are we talking pure ice? Or is it more likely to be a dirty mix of ice dust and rock? To what extent is the ice fractured with crevases?

Near the base this old ice should not be fractured or porous; comparable to a sturdy Antarctic ice sheet.  Surface properties might vary with the particular lag cover found in each crater.

Ice content can be > 75 vol%.  Bramson et al. (https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2015GL064844), interpreting data from three craters in Arcadia Planitia:

Quote
...the material in the upper decameters of the surface is excess ice of up to 75% volumetric fraction ice. Because we can only compute a bulk dielectric constant from surface to base of the radar-detected subsurface interface, this value likely includes the effects of a desiccated regolith layer at the surface, which could bias the interpretation toward lower ice contents. Our results can only place constraints on the overall composition, ignoring the finer structure that likely exists in the upper decameters of the subsurface.

Are methane cathrates present anywhere and how stabel are they?

Maybe SpaceX is planning to melt exploratory wells at locations accessible from Mars Base Alpha.  One of their candidate sites is close to the Phlegra Montes graben glacier, which has a very unusual volcanic wet-base history that raises the possibility of methane clathrate within the glacier (https://forum.nasaspaceflight.com/index.php?topic=45762.msg1987648#msg1987648).
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/09/2019 01:12 pm
I can imagine a large melted out cavern. Pressurize it and then spray water at the walls to plug the holes. All done with "air" temperatures below 0C. Once "sealed" build your habitats inside and make sure that the temperature outside of your habitats are kept below zero.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/09/2019 03:10 pm
I can imagine a large melted out cavern. Pressurize it and then spray water at the walls to plug the holes. All done with "air" temperatures below 0C. Once "sealed" build your habitats inside and make sure that the temperature outside of your habitats are kept below zero.

Nice. The children can go outside to play on ice or snow.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 10/09/2019 04:44 pm
So if 40deg N lat
90-25-40=25

So the sun will be just 25 deg above the horizon in northern hemisphere winter. So it might be advisable to adjust the solar panel tilt as the seasons go by.

The base will need a lot of power with melting all that ice and making CH4 for the return trip.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/09/2019 06:41 pm
Aerogel

Excavated hab spaces require excellent insulation.  Aerogel could be manufactured onsite for this purpose.  Aerogel is > 99% air, so cargo mass is modest.  Aerogel also provides excellent soundproofing.

Manufacture can be a one-pot process [Wang et al. 2015], and embedded fibers can reinforce [Linhares et al. 2019].

Victoria blue aerogel (from powder 'D') or other colored aerogel could give a continuous Earth-sky coloration to ceilings; e.g., when illuminated on metal pressure plates or on discolored ice vaults.  (Aerogel without dyes is blue against dark surfaces, but yellow against bright surfaces.)

Quote from: Wang et al. 2014
(https://www.researchgate.net/profile/Jin_Wang124/publication/266255773/figure/fig14/AS:668698276806673@1536441501681/mages-of-colored-aerogel-powers-A-CuCl-2-silica-B-methyl-orange-silica-C.png)

Fig. 5.  Images of colored aerogel powers: (A) CuCl2–silica, (B) methyl orange–silica, (C) rhodamine B–silica, and (D) victoria blue B–silica composite aerogels. 

Refs

Linhares, T., Amorim, M. T., & Durães, L. (2019). Silica aerogel composites with embedded fibres: a review on preparation, properties and applications. Journal of Materials Chemistry A.

Wang, J., Zhang, Y., Wei, Y., & Zhang, X. (2015). Fast and one-pot synthesis of silica aerogels via a quasi-solvent-exchange-free ambient pressure drying process. Microporous and Mesoporous Materials, 218, 192-198.

Wang, J., Wei, Y., He, W., & Zhang, X. (2014). A versatile ambient pressure drying approach to synthesize silica-based composite aerogels. RSC Advances, 4(93), 51146-51155.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/09/2019 08:22 pm
Also notice that nothing in his answer favors TBMs over other types of tunneling technology.

Well....

"Q: Are you going to bring a Boring Machine to the Moon or Mars?

Elon Musk: I think that would be a good idea"


- I personally think roadheaders are a better idea, initially.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/09/2019 08:55 pm
LMT, Aerogel expands to 99 pct air on Earth, but how well will it aerate on Mars (6 mbar)?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/09/2019 09:29 pm
LMT, Aerogel expands to 99 pct air on Earth, but how well will it aerate on Mars (6 mbar)?

It worked on Mars rovers (https://mars.nasa.gov/mer/mission/rover/temperature/#aerogel).  And of course you'd manufacture indoors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/10/2019 01:32 am
Also notice that nothing in his answer favors TBMs over other types of tunneling technology.

Well....

"Q: Are you going to bring a Boring Machine to the Moon or Mars?

Elon Musk: I think that would be a good idea"


- I personally think roadheaders are a better idea, initially.

Sorry, meant to say nothing in his reasoning supports TBMs over road-headers (though obviously LMT disagrees).

And again, that could easily be a fried chicken "sure why not." Point being it's a bit overreaching and premature to declare TBMs Over All on the basis of that quote.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/10/2019 01:43 am
LMT, Aerogel expands to 99 pct air on Earth, but how well will it aerate on Mars (6 mbar)?

It worked on Mars rovers (https://mars.nasa.gov/mer/mission/rover/temperature/#aerogel).  And of course you'd manufacture indoors.
Yes, it worked well on rovers and it is a great insulator for houses. I agree you would manufacture aerogel sheets indoors.

What I was thinking about is using it as spray-on insulation inside or outside a Mars habitat - would it get enough gas in a low-pressure atmosphere to expand the sol into a gel before hardening? My follow-up thought was yes, because the air pressure comes from inside a spray gun rather than the atmosphere. In fact, iy may work better on Mars because the gel expansion is working against the atmosphere, so less atm pressure should let it expand faster.
Title: Re: Envisioning Amazing Martian Habitats
Post by: _MECO on 10/10/2019 04:00 pm
I'm completely new to this thread (129 pages in!) and I've been reading a lot of suggestion and analysis, and I've seen a lot of people shooting down tunneling ideas. I apologize if this has been explained over and over again in the thread already, but why are tunnels so bad? Difficulty in manufacturing aside, they require similar amounts of material to construct as a basic inflatable hab unit, except they can be made to have arbitrarily large internal volume proportional to the length of the tunnel.

I can imagine an entrance either being dug either as a shallow ramp into flat rock, or as a horizontal channel carved into a rock face or the side of a crater. The area directly preceding the entrance could be reinforced with a marscrete lip to prevent rocks and regolith from sliding into it, and after that you could have the original boring machine path be significantly necked down with regolith infill and more marscrete such that two or three redundant, small bulkheads could be installed. After that you'd have a blind tunnel which has been sprayed with a precautionary sealant and then partially inlaid with insulating material and deck grating. Life support and other equipment could be stored below this grating.

 For large operations, a second unpressurized blind tunnel could be bored parallel to the first and linked with small connecting tunnels containing more redundant bulkheads. This second bored tunnel could contain various construction, exploration, ISRU, mining, excavation equipment, as well as unpressurized storage, etc. and have a wide-open garage entrance to the surface several meters away from the inhabited tunnel. You could install intermediary bulkheads in the pressurized tunnel as needed for safety, expand into the side of the rock opposite the garage tunnel in a pressurized work environment using standard excavation equipment, and not have to deal with radiation at all. For an equivalently sized structure made on or near the surfac one would need far more material to build it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/10/2019 06:18 pm
MECO, ISTM tunneling is a good approach and has its advantages. From the viewpoint of early landings, however, surface habs can be set up more quickly and the equipment required for set-up can be simpler and multi-purpose.

An example of an early habitat could be the crew section of a Starship that has just landed. Musk has said that some of the early SS vehicles may be left on Mars for this purpose.

After landing, SS could be laid on its side using a multipurpose crane. Then passageways could be cut from the crew section through to the pressurized LOX and CH4 tanks using steel cutting and welding equipment. This step would quickly expand the habitable volume.

Then radiation shielding could be added by trenching and filling. First, a level-bottom trench would be dug to a depth of one-half diameter of SS (4.5m), using a multipurpose loader. SS would be pulled horizontally into the shallow trench on rollers. Then the loose fill from trenching would be placed over the semi-buried cylinder. This operation would employ tools that would also be used for building roads, landing pads and surface mining.

As the settlement is further developed, it may be time to bring in a tunnel boring machine. It would be employed to dig straight lengths of tunnels and a road header could be used for curves. This operation would be more expensive initially but may develop habitable volume more quickly in the long run.
Title: Re: Envisioning Amazing Martian Habitats
Post by: _MECO on 10/10/2019 06:28 pm
MECO, ISTM tunneling is a good approach and has its advantages. From the viewpoint of early landings, however, surface habs can be set up more quickly and the equipment required for set-up can be simpler and multi-purpose.

An example of an early habitat could be the crew section of a Starship that has just landed. Musk has said that some of the early SS vehicles may be left on Mars for this purpose.

After landing, SS could be laid on its side using a multipurpose crane. Then passageways could be cut from the crew section through to the pressurized LOX and CH4 tanks using steel cutting and welding equipment. This step would quickly expand the habitable volume.

Then radiation shielding could be added by trenching and filling. First, a level-bottom trench would be dug to a depth of one-half diameter of SS (4.5m), using a multipurpose loader. SS would be pulled horizontally into the shallow trench on rollers. Then the loose fill from trenching would be placed over the semi-buried cylinder. This operation would employ tools that would also be used for building roads, landing pads and surface mining.

As the settlement is further developed, it may be time to bring in a tunnel boring machine. It would be employed to dig straight lengths of tunnels and a road header could be used for curves. This operation would be more expensive initially but may develop habitable volume more quickly in the long run.

The starship on its side gutted for space and shielded with regolith does sound excellent! I bet six or seven connected via passageways would make an excellent starting base before a real TBM can be assembled.
Title: Re: Envisioning Amazing Martian Habitats
Post by: WTF on 10/10/2019 10:22 pm
MECO, ISTM tunneling is a good approach and has its advantages. From the viewpoint of early landings, however, surface habs can be set up more quickly and the equipment required for set-up can be simpler and multi-purpose.

An example of an early habitat could be the crew section of a Starship that has just landed. Musk has said that some of the early SS vehicles may be left on Mars for this purpose.

After landing, SS could be laid on its side using a multipurpose crane. Then passageways could be cut from the crew section through to the pressurized LOX and CH4 tanks using steel cutting and welding equipment. This step would quickly expand the habitable volume.

Then radiation shielding could be added by trenching and filling. First, a level-bottom trench would be dug to a depth of one-half diameter of SS (4.5m), using a multipurpose loader. SS would be pulled horizontally into the shallow trench on rollers. Then the loose fill from trenching would be placed over the semi-buried cylinder. This operation would employ tools that would also be used for building roads, landing pads and surface mining.

As the settlement is further developed, it may be time to bring in a tunnel boring machine. It would be employed to dig straight lengths of tunnels and a road header could be used for curves. This operation would be more expensive initially but may develop habitable volume more quickly in the long run.

The starship on its side gutted for space and shielded with regolith does sound excellent! I bet six or seven connected via passageways would make an excellent starting base before a real TBM can be assembled.

AIUI, the very first two Starships (first synod) are not scheduled to return ... so thats a start.
Title: Re: Envisioning Amazing Martian Habitats
Post by: BZHSpace on 10/11/2019 10:21 am
About my old message from the 09/10/2019 :
Quote
I saw your works and enjoy them, I'm in architecture school so I will make a concept of a Mars habitat/city that I will show on this thread. Maybe on the begining of January/February. My concept will be a propostion of a single module, and how differents module could built a city (auto-sufficient city).

So my first task was to analyse many structural scheme to understand how a village/city work, I don't think if we focus on a simple habitat we succeded to build a city/base on Mars. So I start to make research about many village/tomb structure so it's come three model which I will develop in my "project" I will show to you :
- African village (traditional)
- Chinese village (circular)
- Megalithic tumulus (tomb complex)



I will develop a concept which is realistic according to the realities of the Starship, I will introduce how larger modules will come with the SS18 and how the modules will be assemble. My approach is based on the understatement of the biological - ancient structure which answer many constraints because ancient people were confront to many threat to their own safety such as invasion, etc.


I will explain to you many concept about :

- reuse ressources
- collect energy
- protect from the gamma ray
- product food
- working
- economy concept (introduction to a circualar philosophy)

My work will be avalable on January/February.


- BZH Space -

Title: Re: Envisioning Amazing Martian Habitats
Post by: WTF on 10/11/2019 10:11 pm
MECO, ISTM tunneling is a good approach and has its advantages. From the viewpoint of early landings, however, surface habs can be set up more quickly and the equipment required for set-up can be simpler and multi-purpose.

An example of an early habitat could be the crew section of a Starship that has just landed. Musk has said that some of the early SS vehicles may be left on Mars for this purpose.

After landing, SS could be laid on its side using a multipurpose crane. Then passageways could be cut from the crew section through to the pressurized LOX and CH4 tanks using steel cutting and welding equipment. This step would quickly expand the habitable volume.

Then radiation shielding could be added by trenching and filling. First, a level-bottom trench would be dug to a depth of one-half diameter of SS (4.5m), using a multipurpose loader. SS would be pulled horizontally into the shallow trench on rollers. Then the loose fill from trenching would be placed over the semi-buried cylinder. This operation would employ tools that would also be used for building roads, landing pads and surface mining.

As the settlement is further developed, it may be time to bring in a tunnel boring machine. It would be employed to dig straight lengths of tunnels and a road header could be used for curves. This operation would be more expensive initially but may develop habitable volume more quickly in the long run.

The starship on its side gutted for space and shielded with regolith does sound excellent! I bet six or seven connected via passageways would make an excellent starting base before a real TBM can be assembled.

The downcomer ...
Once the Starship is horizontal, perhaps it could be used for moving "stuff" from one end of the ship to the other. Even crew, if the dimensions are adequate. Reduce the fabrication needed.

I prefer my crow with mustard.

CORRECTION:

Typo corrected.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/12/2019 03:54 am
I'm pleasantly surprised at the shielding effectiveness of CO2 ice. Starts at 40g/cm2 for 100gm/cm2 of shielding. Looks like it cuts the surface dose by half with no problems (halve the dose rate due to the planet surface). That would be a slab ~60cm thick.
Curiosity measured 0.64mSv/day already. Why does your graph start so much higher?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 10/12/2019 03:57 am
An extendable and expandable habitat module.
Used in the early days, before extensive underground construction from in-situ materials.
All the interior partitions would be assembled after expansion, and stored inside the rigid part.
Heh, there's a prototype of one of these in one of the buildings at NASA Langley.
Really ?  Cool!  Any pictures?  Specs?

I assume he means the "planetary surface habitat and airlock unit (https://www.nasa.gov/centers/langley/news/researchernews/rn_inflatable-lunar-hab.html)":

(https://www.nasa.gov/centers/langley/images/content/170068main_influnarhab01-1024.jpg) (https://www.nasa.gov/centers/langley/images/content/170068main_influnarhab01-1024.jpg)

But there's also the "X-HAB" (50+ page PDF (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100017479.pdf)):

(https://www.researchgate.net/profile/Sandra_Haeuplik-Meusburger/publication/254255494/figure/fig7/AS:284422759829512@1444823078751/Deployment-Testing-of-the-X-Hab-Lunar-Habitat-at-NASA-LaRC-credit-NASA-ILC-Dover.png) (https://www.researchgate.net/profile/Sandra_Haeuplik-Meusburger/publication/254255494/figure/fig7/AS:284422759829512@1444823078751/Deployment-Testing-of-the-X-Hab-Lunar-Habitat-at-NASA-LaRC-credit-NASA-ILC-Dover.png)

Both from ILC Dover, both via LaRC.

["X-Hab" was also the name of a NASA student design contest. Don't know if the Langley thing spun off from that, or is just someone not researching their acronyms.]
The bottom one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Norm38 on 10/12/2019 04:39 am
So how does everyone's preconceived notions change if all of a sudden it's huge stainless steel structures being left on Mars?  That can then be moved and modded at will?

There's no need to fly back the stages for reuse if the whole ship is payload.
Do targeted reuse, maybe pulling the engines and thrusters.  I bet pumps, tanks, hoses and cables can all be reused.  Avionics too, if they're built to be used later to run things.

So now a whole lot of high quality mass is being dropped with each mission.  What a creative reuse culture will develop off that. 



Question:  What kind of "blanket" would you need to drape over a landed SS to help improve insulation for crew against the cold, and also provide radiation shielding.  (I mean while vertical, not buried)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/12/2019 09:39 am
Re: "blanket" I am guessing that a mylar tent, black on the outside and gold-reflective on the inside, would help the vertical Starship with temperature regulation. Or perhaps not. I'm no expert...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/12/2019 03:07 pm
...
...
So now a whole lot of high quality mass is being dropped with each mission.  What a creative reuse culture will develop off that. 
...
...
Question:  What kind of "blanket" would you need to drape over a landed SS to help improve insulation for crew against the cold, and also provide radiation shielding.  (I mean while vertical, not buried)
  Many kinds of insular blankets would help to retain heat. Which one is more cost and mass efficient?

In the case of GCR, we still don’t have a clearly focussed picture of the required protective layer. The main purpose of placing SS horizontal and into a trench with a regolith cover is GCR radiation protection. If this could be solved with a protective blanket, horizontal positioning may not be necessary.

Added: Even if SS habitats were employed in vertical positions, some SS’s in horizontal position could serve as hallways between “towers.”

Added #2: Even better would be 2.5m wide steel sheets transported to Mars. They would be welded into x meter diameter rings and stacked horizontally to produce inter-tower hallways (like Boca Chica construction).
Title: Re: Envisioning Amazing Martian Habitats
Post by: livingjw on 10/12/2019 05:00 pm
So how does everyone's preconceived notions change if all of a sudden it's huge stainless steel structures being left on Mars?  That can then be moved and modded at will?

There's no need to fly back the stages for reuse if the whole ship is payload.
Do targeted reuse, maybe pulling the engines and thrusters.  I bet pumps, tanks, hoses and cables can all be reused.  Avionics too, if they're built to be used later to run things.

So now a whole lot of high quality mass is being dropped with each mission.  What a creative reuse culture will develop off that. 



Question:  What kind of "blanket" would you need to drape over a landed SS to help improve insulation for crew against the cold, and also provide radiation shielding.  (I mean while vertical, not buried)

The crew compartment is already heavily insulated, so I assume you are talking about turning the tanks into living space?

John
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/12/2019 08:21 pm
...
,,,
The crew compartment is already heavily insulated, so I assume you are talking about turning the tanks into living space?

John
Yes, tanks but also crew section.

SpX plans to insulate the crew compartment for temperature control and solar storm radiation. But GCR is another level of protection, requiring an H-rich layer of H2O, CH4 or hydrocarbon. Could be as much as 1m of H2O to capture secondary particles derived from proton bombardment. May not ne practical to provide complete protection. (Added: At least for the interplanetary trip.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/12/2019 08:47 pm
I made a rough estimate of the mass required to provide 1m H2O protection to compact sleeping quarters inside SS.

https://forum.nasaspaceflight.com/index.php?topic=47064.260


Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/13/2019 02:01 am
I'm completely new to this thread (129 pages in!) and I've been reading a lot of suggestion and analysis, and I've seen a lot of people shooting down tunneling ideas. [...] why are tunnels so bad?

It's not that they are "bad", it's just that their advantages are outweighed by the difficulty of tunnelling.

In real-world examples, engineering/construction companies always dig open trenches from the top if the option is available, build the enclosure and backfill. Tunnelling is a last resort if external factors make it too expensive to dig from the top (usual examples are existing surface infrastructure, or that there's mountains in the way.)

When discussing tunnelling, it's also worth separating TBMs (as used by The Boring Company) from excavation using other equipment like road-headers. The latter don't have to dig literal "tunnels", and can just excavate any self-supporting cavity. TBMs are extremely limited in what they can do. You can't cross-cut links nor dig branches, for example. They also put infrastructure burdens on the rest of the operation that prevents you from using the tunnel until it's completely finished. And even removing the TBM is (apparently) painful (enough that some projects have just buried the TBM rather than trying to remove it.) Also, TBMs require road-headers to get them into the tunnel (they usually can't dig the entrance, can't dig ramps, etc.) So you'll need other excavating equipment in order to use a TBM. Since there's no reason to actually want a long narrow tunnel for a habitat, why not skip the TBM and use the other equipment to dig out the hab volume?

It's also worth remembering that tunnelling requires access to the tunnel to remove the excavated material. You can't really use the tunnel until the entire operation is finished. I think people picture the tunnelling as an ongoing process as you expand. Ie, build your entrance and start fitting out the airlocks and initial hab areas while the tunnelling machine is still excavating further in; as each new section that gets tunnelled, you just extend the pressurised hab. But you can't block the tunnel between the cutting face and outside.

Difficulty in manufacturing aside, they require similar amounts of material to construct as a basic inflatable hab unit, except they can be made to have arbitrarily large internal volume proportional to the length of the tunnel.

Scraping some fill over a surface hab is mechanically easier than digging into high quality rock by such a significant margin that they aren't even on the same page.

In terms of cost (which reflects man-power requirement, amount of equipment, equipment replacement rates, etc), you have options in the following order (easiest to hardest):

Surface hab, covered with loose regolith.
Building the base/settlement in a lava tube (a personal favourite) if sloped access is available naturally.
Surface hab, covered with bagged regolith or regolith blocks.
Buried hab, trench-cut and backfilled with loose regolith.
Buried hab, covered with regolith blocks, then backfilled.
Building the base/settlement in a lava tube, if an entrance has to be dug.
Surface hab, covered with simple manufactured shielding, such as ice/regolith mixes.
Buried hab, covered with manufactured ice/regolith mixes.

gap

Surface hab, covered with complex ISRU manufactured shielding, such as low-Z plastic.

gap

Tunnelling [excavating habitat cavities] into coherent rock with road-header/etc.

bigger gap

Tunnelling into coherent rock using a purpose built TBM.

[My fondness for lava tubes comes from the possibility that they have collected moisture from the air over billions of years due to the freeze-pump effect, even fairly close to the equator. So they'll be partially filled with water ice. Shelter, shielding, water. What's not to love.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/13/2019 03:00 am
Re: Stainless steel imports.

Can anyone with access to OLTARIS answer a question:
If you built a pressure vessel made of steel on the Martian surface (whether or not you are using Starship, or melting it down and making a custom design) inside of a regolith or ice+regolith cover, what is the required shield depth. Does the steel make the radiation worse?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 10/13/2019 09:51 am
Re: Stainless steel imports.

Can anyone with access to OLTARIS answer a question:
If you built a pressure vessel made of steel on the Martian surface (whether or not you are using Starship, or melting it down and making a custom design) inside of a regolith or ice+regolith cover, what is the required shield depth. Does the steel make the radiation worse?

The radiation shield thickness needed is roughly 2m of regolith + water ice.

On general principles we know that the contents of steel -- Iron and Chromium -- have relatively low atomic numbers (26 and 24). As such, they shouldn't cause much Bremsstralung (secondary) radiation.

Regolith probably mostly consists of elements like Al, Cl, O and Si, which are all low-Z.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/13/2019 02:41 pm
...
...
In terms of cost (which reflects man-power requirement, amount of equipment, equipment replacement rates, etc), you have options in the following order (easiest to hardest):

Surface hab, covered with loose regolith.
Building the base/settlement in a lava tube (a personal favourite) if sloped access is available naturally.
Surface hab, covered with bagged regolith or regolith blocks.
Buried hab, trench-cut and backfilled with loose regolith.
Buried hab, covered with regolith blocks, then backfilled.
Building the base/settlement in a lava tube, if an entrance has to be dug.
Surface hab, covered with simple manufactured shielding, such as ice/regolith mixes.
Buried hab, covered with manufactured ice/regolith mixes.
...
...
I like your cost ladder.

In the case of a settlement built over regolith that is roughly the same hardness throughout, options 1 and 4 (bolded) may be about the same cost. In both cases you have to scrape up regolith for a hab covering. So you might as well scrape up regolith to form a trench and use that material for the covering.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/13/2019 03:18 pm
On second thought, surface regolith is unlikely to be the same hardness throughout. Rather, loose regolith is likely to be a thin surface layer of loose material (due to slight warming of the sun) and very hard underneath. Paul451 has the right ordering of cost for protective covering.

When only the top few cm ls loose material, a logical sequence of construction could be as follow:

Give high priority to scraping loose regolith to develop flat areas for development, such as landing pads, roadways and habitat pads.
Let exposed areas receive sunlight for a few sols and then return to scrape another layer.
Assemble piles of loose material to be hauled later.
When regolith cover is needed, load material from regolith piles into a bulk hauling vehicle and dump in the desired location.
A simple screen may be neeeded to remove coarse rocks.

Edit: spelling
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 10/13/2019 03:30 pm
...
...
In terms of cost (which reflects man-power requirement, amount of equipment, equipment replacement rates, etc), you have options in the following order (easiest to hardest):

Surface hab, covered with loose regolith.
Building the base/settlement in a lava tube (a personal favourite) if sloped access is available naturally.
Surface hab, covered with bagged regolith or regolith blocks.
Buried hab, trench-cut and backfilled with loose regolith.
Buried hab, covered with regolith blocks, then backfilled.
Building the base/settlement in a lava tube, if an entrance has to be dug.
Surface hab, covered with simple manufactured shielding, such as ice/regolith mixes.
Buried hab, covered with manufactured ice/regolith mixes.
...
...
I like your cost ladder.

In the case of a settlement built over regolith that is roughly the same hardness throughout, options 1 and 4 (bolded) may be about the same cost. In both cases you have to scrape up regolith for a hab covering. So you might as well scrape up regolith to form a trench and use that material for the covering.
There is a detail, which has occasionally been mentioned and occasionally discussed in detail, amongst the very many times burying habitats under loose regolith has been discussed. That is the strength of the structure being buried.
This is not only the ability of the pressurised habitat being able to resist the overall weight of cover. (1 bar =about 10 tonnes(f)/m2 or 100kN/m2 ), but also resistance to deformation, and puncturing, and ability to support the cover if depressurised, during construction, maintenance, or accident etc. It is far from clear if for example an SS body on its side could safely be just buried in loose regolith using a bucket loader, or whether an additional strong layer is needed, whether that is sandbags, rigid masonary arch sections, frozen water... etc...

 The starship skin is expected to thin from its believed current 5mm.
Ignoring the issue implies the process is simple fast and cheap, which is likely not the whole story.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/13/2019 03:40 pm
...
...
In terms of cost (which reflects man-power requirement, amount of equipment, equipment replacement rates, etc), you have options in the following order (easiest to hardest):

Surface hab, covered with loose regolith.
Building the base/settlement in a lava tube (a personal favourite) if sloped access is available naturally.
Surface hab, covered with bagged regolith or regolith blocks.
Buried hab, trench-cut and backfilled with loose regolith.
Buried hab, covered with regolith blocks, then backfilled.
Building the base/settlement in a lava tube, if an entrance has to be dug.
Surface hab, covered with simple manufactured shielding, such as ice/regolith mixes.
Buried hab, covered with manufactured ice/regolith mixes.
...
...
I like your cost ladder.

In the case of a settlement built over regolith that is roughly the same hardness throughout, options 1 and 4 (bolded) may be about the same cost. In both cases you have to scrape up regolith for a hab covering. So you might as well scrape up regolith to form a trench and use that material for the covering.

Even assuming uniform hardness, option 1 moves dirt once while option 4 moves dirt twice. Seems obvious, but this first-order effect shouldn't be ignored. Furthermore in option 1 the excavation is unconstrained (ie the hole can take the most convenient and cheapest shape), while in option 4 the hole is constrained to the size/shape of the hab.



On second thought, surface regolith is unlikely to be the same hardness throughout. Rather, loose regolith is likely to be a thin surface layer of loose material (due to slight warming of the sun) and very hard underneath. Paul451 has the right ordering of cost for protective covering.

When only the top few cm ls loose material, a logical sequence of construction could be as follow:

Give high priority to scraping loose regolith to develop flat areas for development, such as landing pads, roadways and habitat pads.
Let exposed areas receive sunlight for a few sols and then return to scrape another layer.
Assemble piles of loose material to be hauled later.
When regolith cover is needed, load material from regolith piles into a bulk hauling vehicle and dump in the desired location.
A simple screen may be neeeded to remove coarse rocks.

Edit: spelling


Alternative: locate near a convenient scree pile.

Alternative alternative: blasting.

There's a reason scraping is typically used for grading, not for bulk excavation. It's far less efficient in terms of material moved per hour per tonne of equipment (or per tonne of replacement parts, for that matter). That fact doesn't change on Mars, so alternative solutions to the Hard Regolith problem above might be superior. Worth looking into.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Barley on 10/13/2019 03:51 pm

Alternative: locate near a convenient scree pile.

Locate near an unstable pile next to an unstable slope that is dropping rocks on it?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/13/2019 04:30 pm

Alternative: locate near a convenient scree pile.

Locate near an unstable pile next to an unstable slope that is dropping rocks on it?

Hence "near," not "right next to." :P
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/13/2019 08:41 pm
...
..
There is a detail, which has occasionally been mentioned and occasionally discussed in detail, amongst the very many times burying habitats under loose regolith has been discussed. That is the strength of the structure being buried.
This is not only the ability of the pressurised habitat being able to resist the overall weight of cover. (1 bar =about 10 tonnes(f)/m2 or 100kN/m2 ), but also resistance to deformation, and puncturing, and ability to support the cover if depressurised, during construction, maintenance, or accident etc. It is far from clear if for example an SS body on its side could safely be just buried in loose regolith using a bucket loader, or whether an additional strong layer is needed, whether that is sandbags, rigid masonary arch sections, frozen water... etc...

 The starship skin is expected to thin from its believed current 5mm.
Ignoring the issue implies the process is simple fast and cheap, which is likely not the whole story.
You are right. If SpX plans to lay their landed SS horizontally, they have to design its structure accordingly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/13/2019 09:00 pm
Earlier I posted a proposed SS lying in a trench with enhancements. Features included an arch composed of ice blocks over the trench (GCR protection) and a void between the arch and SS for vacuum bottle insulation. I am showing it here because the arch takes up compressive forces that would otherwise bear directly on the side of SS lying in the trench. This approach could help with the structural problems pointed out by Distant Temple.

https://forum.nasaspaceflight.com/index.php?topic=41427.msg1958871#msg1958871
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 10/13/2019 11:40 pm
Earlier I posted a proposed SS lying in a trench with enhancements. Features included an arch composed of ice blocks over the trench (GCR protection) and a void between the arch and SS for vacuum bottle insulation. I am showing it here because the arch takes up compressive forces that would otherwise bear directly on the side of SS lying in the trench. This approach could help with the structural problems pointed out by Distant Temple.

https://forum.nasaspaceflight.com/index.php?topic=41427.msg1958871#msg1958871
Excellent Ionmars. (Edit: I have just gone back and read your linked post and the nearby ones)
It doesn't look too hard. But its certainly more careful work than just heaping regolith. Likely involving EVA time.
Of course a hab designed to be buried, could also include the necessary strength.
Both of these methods (SS under ice arch, or stronger hab built to be buried) add to the cost/effort of the bury method. However probably not enough to alter Paul451's order of simplicity!

Mentioning ice though reminds me of fantastic ideas of building habs in Ice! Ice doesn't need a TBM, and has to be mined for ISRU. so whether it is melted in a well, cut with saws, or dug with a backhoe or road-header, it can be done to form usable caves, and caves that have natural shielding.  Also if the mining is not difficult, cutting blocks for building with is also possible. They will need some protection from sublimation...

This should be added to your list Paul451, in some way.

It would be great to index this thread, or make it into a wiki etc... as it is packed full of fantastic work, which we/I keep forgetting/repeating!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/13/2019 11:50 pm

If SpX must add structural elements to make SS more usable, those elements should count as part of the useful payload delivered to Mars.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 10/14/2019 12:03 am
This is probably discussed upthread... if SX starts their base where there is an underground layer of ice, say ar least 10m thick, then digging down into the ice, and then carving horizontal rooms will provide excellent shielding, whilst the spoil is fed into the ISRU. Habs will only need to be pressure vessels, and be insulated! Whatever machines needed for mining ice for ISRU will still be used. An overburden of regolith on top of the ice, may be difficult to dig through initially, but once a shaft(or ramp etc) is constructed, as long as the ice caves are strong enough to support it, it will just add to the shielding.

So all those pretty pictures of mars bases are all wrong. There will be a couple of odd bits on the surface, and a city tunnelled into the ice below!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/14/2019 01:20 am
Tempting as the ice boring approach may be, I believe Paul451 has correctly identified the order of cost of different operations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/14/2019 02:40 am
[1] Surface hab, covered with loose regolith.
[4] Buried hab, trench-cut and backfilled with loose regolith.
In the case of a settlement built over regolith that is roughly the same hardness throughout, options 1 and 4 (bolded) may be about the same cost. In both cases you have to scrape up regolith for a hab covering. So you might as well scrape up regolith to form a trench and use that material for the covering.
Even assuming uniform hardness, option 1 moves dirt once while option 4 moves dirt twice.

Because moving a pile of dirt is going to be the major expense.

I see this argument from you and other people trying to cut down on the volume of regolith by suggesting containment (bags, sintered blocks, complex shield material, etc), as if a pile of dirt is somehow so expensive or complex that a manufactured process that reduces the regolith volume by 40-60% is worthwhile.

There's a reason scraping is typically used for grading, not for bulk excavation.

There's a wide array of options between grading and using explosives. And the machines (rippers, trench-cutters, excavators/backhoes, bucket loaders) are going to be generally useful elsewhere. Especially if you are "mining" for water.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/14/2019 02:41 am
Mentioning ice though reminds me of fantastic ideas of building habs in Ice! [...] it can be done to form usable caves, and caves that have natural shielding.  Also if the mining is not difficult, cutting blocks for building with is also possible. [...]
This should be added to your list Paul451, in some way.

The list was meant to just reflect the difficulty in construction. So there needs to be a extra reason, an additional benefit, for choosing an option further down the list. My point was that TBMs into solid bedrock almost certainly doesn't provide such a benefit.

Digging into ice might provide such a reason, and it's been discussed before for that reason. Anything that provides "free" living volume will change the cost/benefit.

This is the case with cut'n'cover trenching as well. If you need to excavate for regolith as shielding, scraping a top layer might not be as efficient as digging a decent hole, in which case, the hole might give you a partial or full burial depth for the habs for "free". It depends on local conditions, hab design, size of the settlement, rate of expansion, etc.

It would be great to index this thread, or make it into a wiki etc... as it is packed full of fantastic work, which we/I keep forgetting/repeating!

Heh. Go for it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 10/14/2019 06:12 am
[1] Surface hab, covered with loose regolith.
[4] Buried hab, trench-cut and backfilled with loose regolith.
In the case of a settlement built over regolith that is roughly the same hardness throughout, options 1 and 4 (bolded) may be about the same cost. In both cases you have to scrape up regolith for a hab covering. So you might as well scrape up regolith to form a trench and use that material for the covering.
Even assuming uniform hardness, option 1 moves dirt once while option 4 moves dirt twice.


Remember that with Option 4 you are only moving about half the volume of dirt as in Option 1 so there is a balance there.

Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 10/14/2019 12:34 pm
The "COST" of digging holes and burying habs in regolith is effectively not constant. Also its PRIORITY changes quickly. Hab space is not all the same, or for the same purpose, and radiation varies. There will be progression something like this:

Shelters for solar storms will be needed, which can start off at a minimum size, for survival only.
Sleeping accommodation, which will likely include the shelters, and could be initially dense, with bunks etc.
High use living and working accommodation.
Necessarily spacious living and working space
Expansion for convenience, efficiency, luxury and mental health etc.


I would design space that allowed everyone to have shelter and sleeping spaces. These would involve the efforts discussed in posts above, with burial, and regolith and/or ice shielding. They would be designed to be set up quickly, which would involve strong and simple, resilient structures, materials, and components delivered from Earth. It would include duplication of critical components and machines. If all items land 100% successfully(and accessibly), this would give twice the machinery (and habs) needed, so digging and shifting regolith would be fast and cheap, to be concentrated on deploying half (or less) of the habs for critical shelter, then for bunked sleeping.
... split because of TL/DR !!! ...
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 10/14/2019 12:35 pm
... TL/DR ... continued:

Once "shelter and bunkhouse" is achieved, prospecting, then digging for ice for ISRU can begin. This may well mean clearing regolith for a shaft, ramp, or opencast working. Spoil can hopefully be deposited at nearby hab construction sites for shielding. This will take place over an extended time, and more effort could be invested in setting up mining machinery such as hoppers and conveyors. The full compliment of shelter style habs could be deployed to increase comfort for sleeping and personal space.

Also once "shelter and bunkhouse" is achieved larger "hab" space can be deployed that may be used initially with limited or no shielding, as people will only spend part of their days there, such as pressurised/shirtsleeve storage and workshop.

Also once "shelter and bunkhouse" is achieved, structures involving more use of Martian resources like cut blocks of ice, "Marscrete", deeper planned excavations, and just larger spaces can begin.

These developments would provide adequate "high use living and working accommodation", and expand this for some comfort, convenience and efficiency.

Only then are ideas like mining for accommodation,  rotating an SS to horizontal -and burying it! exploring for lava tubes etc considered. Human-power will be limited as it will be split between may key functions and no longer all focused on habs for immediate survival. The "survival" element will mow be the reliability, scale and trajectory of ISRU! -with its needs of mining, ISRU plant, CO2 collection, gas storage, plumbing etc. and secondly landing/launch pads! 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/14/2019 12:37 pm
Re: Stainless steel imports.

Can anyone with access to OLTARIS answer a question:
If you built a pressure vessel made of steel on the Martian surface (whether or not you are using Starship, or melting it down and making a custom design) inside of a regolith or ice+regolith cover, what is the required shield depth. Does the steel make the radiation worse?

Depends on the thickness of steel and its placement in the shielding sequence. Steel is definitely not as good an outer buffer as is aluminium or plastic, but behind 20g/cm2 of Martian atmosphere and a couple of metres of regolith/ice-regolith cover, it's not going to make that much of a difference. Martian regolith has a significant iron component anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/14/2019 01:59 pm
[1] Surface hab, covered with loose regolith.
[4] Buried hab, trench-cut and backfilled with loose regolith.
In the case of a settlement built over regolith that is roughly the same hardness throughout, options 1 and 4 (bolded) may be about the same cost. In both cases you have to scrape up regolith for a hab covering. So you might as well scrape up regolith to form a trench and use that material for the covering.
Even assuming uniform hardness, option 1 moves dirt once while option 4 moves dirt twice.

Because moving a pile of dirt is going to be the major expense.

Not sure if this is supposed to be sarcasm. It's a major expense, yes. Not sexy, but costly.

I see this argument from you and other people trying to cut down on the volume of regolith by suggesting containment (bags, sintered blocks, complex shield material, etc), as if a pile of dirt is somehow so expensive or complex that a manufactured process that reduces the regolith volume by 40-60% is worthwhile.

Sorry, you must have me confused with someone else.  I'm the "just pile regolith on your hab" guy.

For the walls it's possible that eg HESCO Bastions would save some cost, but I've always maintained that the final solution is a cost-optimal combination of a gravity bank and a reinforced Earth regolith wall. In other words, you never use more advanced containment unless it is worthwhile. Otherwise what would be the point?


There's a reason scraping is typically used for grading, not for bulk excavation.

There's a wide array of options between grading and using explosives. And the machines (rippers, trench-cutters, excavators/backhoes, bucket loaders) are going to be generally useful elsewhere. Especially if you are "mining" for water.

Exactly. I gave two options, but obviously many methods of excavation exist. For instance, using excavators. :D

Scraping is pretty low on the totem pole, and with good reason.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/14/2019 02:14 pm
If SpX were to adopt an “enhanced trench” approach, initially landed Starships could be quickly assembled into a small village with greatly expanded habitable volume.

The sketch below shows a layout of  trenches to accommodate a few initial ships. I assumed cargo SS would be a pressurized alternative to the pressurized passenger version. They would be structurally re-enforced so they could lie horizontally in a trench with added GCR protection. The passenger version would remain upright, but joined into a hallway that connects to other vessels. Hallways are also pressurized so that personnel can transit between pressurized vessels without donning a spacesuit.

Edit: Updated graphic
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 10/14/2019 02:17 pm
The cost in type of machine needed, time taken, humans involved, risk to set up a minimum shelter, a sparse base, or prepare for the next synod's influx, or, or .... depends largely on the geography and geology of the site. From depth of loose regolith to whether there are cliffs, canyons, lava tubes and where the ice is located.

Many questions have to be more specific to the landing site ... more like a plan of action than one or another generic one solution beats them all!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/14/2019 02:36 pm
The cost in type of machine needed, time taken, humans involved, risk to set up a minimum shelter, a sparse base, or prepare for the next synod's influx, or, or .... depends largely on the geography and geology of the site. From depth of loose regolith to whether there are cliffs, canyons, lava tubes and where the ice is located.

Many questions have to be more specific to the landing site ... more like a plan of action than one or another generic one solution beats them all!
I agree. The above trench layout assumes moderate slope, some loose regolith near the surface. and some water ice in the ground. I have in mind Aeolis Arcadia Planitia where SpX has shown interest at a number of locations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/14/2019 04:57 pm
Earlier I posted a proposed SS lying in a trench with enhancements. Features included an arch composed of ice blocks over the trench (GCR protection) and a void between the arch and SS for vacuum bottle insulation. I am showing it here because the arch takes up compressive forces that would otherwise bear directly on the side of SS lying in the trench. This approach could help with the structural problems pointed out by Distant Temple.

https://forum.nasaspaceflight.com/index.php?topic=41427.msg1958871#msg1958871

It's funny, because I started with a design very much like this, before evolving it into the cellular "Waffle hab" I presented in my first post. https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641

Step 1: a buried horizontal cylinder. Unreinforced regolith walls should slope at the angle-of-repose (not shown in the diagram). A worse problem is the slope in the trench, since any slumping would result in a nasty thermal bridge (which risks melting your ice dome). Hard to repair too. Imo expanding foam is a lower risk option.

Step 2: a row of buried horizontal cylinders. Closer together is better to avoid wasting regolith and minimize connecting tunnel mass, concentrating shielding mass on the roof. Analogous to your "enhanced trench." The expanding foam sheath becomes a foam footer (similar to an ICF on Earth), and the interstitial regolith is maintained at room temperature, acting as a thermal battery.

Step 3: a stack of rows of buried horizontal cylinders. :) Arranged like a beehive, naturally. Structurally we should be able to get 3-5 levels, which means 3-5x the amount of habitable volume for the same shielding, and thermal insulation requirements drop by 3-5x.

Step 4: Simplify. Why do we have all this extra regolith in between the cylinders? Delete it (keeping the shielding/thermal regolith roof and walls of course), saving both structural mass and labor on Mars. This also deletes the mass of the connecting tunnels between cylinders, simplifying them down to just a single pressure isolation door (vs the the tunnel which needs two such doors). At this point you also rearrange the pressure vessel shape from a hexgrid of cylinders to a rectilinear grid of walls or beams. This not only saves structural mass, it also "packs" the interior space far better than a cylinder shape (cylinders always end up with awkward corners).

Voila, the Waffle hab!

Many ways to implement this, and many design variations. One obvious solution is a Kevlar pressure restraint, with secondary Marscrete suspension towers in case of depressurization. My BOTE says ~40 tones of Kevlar gives you a Walmart Supercenter size volume on Mars, margins included. :D Or put another way, an entire Starship (tank volume included) for a mere 400 kg! Of course a full system has other components, but this is a pretty good start since the pressure vessel carries the largest structural loads.

The "obvious" tunneling solution isn't so obvious, because the low strength of sedimentary rock means you need a pressure vessel anyway.

Another implementation would be prefab assembly using in-situ Mars steel. Make/test all the parts in a nice pressurized factory building (as needed, obviously some processes are better in vacuum), then truck the parts on-site and assemble/bury (eventually automated by robots). Fully indigenous hab manufacturing, using a mass- and cost-optimized design with "no fat left to trim."

Another implementation is making inflatable habs on Mars from in-situ polymers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/14/2019 10:17 pm
Earlier I posted a proposed SS lying in a trench with enhancements. Features included an arch composed of ice blocks over the trench (GCR protection) and a void between the arch and SS for vacuum bottle insulation. I am showing it here because the arch takes up compressive forces that would otherwise bear directly on the side of SS lying in the trench. This approach could help with the structural problems pointed out by Distant Temple.

https://forum.nasaspaceflight.com/index.php?topic=41427.msg1958871#msg1958871

It's funny, because I started with a design very much like this, before evolving it into the cellular "Waffle hab" I presented in my first post. https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641
This shows how easily some us (me) forget preceding posts in this very long thread. Your idea was excellent and could be an advanced phase of the "enhanced trench" approach.

Quote
Step 1: A buried horizontal cylinder. Unreinforced regolith walls should slope at the angle-of-repose (not shown in the diagram). A worse problem is the slope in the trench, since any slumping would result in a nasty thermal bridge (which risks melting your ice dome). Hard to repair too. Imo expanding foam is a lower risk option.
I like expanding foam insulation. A gap of 0.5m between the side of SS lying horizontal and the ground beneath it could be filled with a bed of foam. Foam may not insulate as well as vacuum, but it would be less prone to damag by accidents

Quote
Step 2: A row of buried horizontal cylinders. Closer together is better to avoid wasting regolith and minimize connecting tunnel mass, concentrating shielding mass on the roof. Analogous to your "enhanced trench." The expanding foam sheath becomes a foam footer (similar to an ICF on Earth), and the interstitial regolith is maintained at room temperature, acting as a thermal battery.
OK, except the part of foam touching SS surface would be room temp and the part touching regolith would be cryogenic cold.

Quote
Step 3: a stack of rows of buried horizontal cylinders. :) Arranged like a beehive, naturally. Structurally we should be able to get 3-5 levels, which means 3-5x the amount of habitable volume for the same shielding, and thermal insulation requirements drop by 3-5x. [
OK, but you will need a span of hard rock or frozen regolith between horizontal cylinders in step 4.

Quote
Step 4: Simplify. Why do we have all this extra regolith in between the cylinders? Delete it (keeping the shielding/thermal regolith roof and walls of course), saving both structural mass and labor on Mars. This also deletes the mass of the connecting tunnels between cylinders, simplifying them down to just a single pressure isolation door (vs the the tunnel which needs two such doors). At this point you also rearrange the pressure vessel shape from a hexgrid of cylinders to a rectilinear grid of walls or beams. This not only saves structural mass, it also "packs" the interior space far better than a cylinder shape (cylinders always end up with awkward corners).

Here is where you need the hard material between cylinders to act as pillars in compression for the next row of cylinders above. Otherwise you will need to import steel beams from Earth for this purpose.

Because this is a step more complex, I would suggest holding the vertical phase of development to a later time when more equipment is available. For the first phase of Mars development, lining up SS cylinders on one level would be easier.
...
...
Edit: quotes
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/14/2019 11:03 pm
Earlier I posted a proposed SS lying in a trench with enhancements. Features included an arch composed of ice blocks over the trench (GCR protection) and a void between the arch and SS for vacuum bottle insulation. I am showing it here because the arch takes up compressive forces that would otherwise bear directly on the side of SS lying in the trench. This approach could help with the structural problems pointed out by Distant Temple.

https://forum.nasaspaceflight.com/index.php?topic=41427.msg1958871#msg1958871

It's funny, because I started with a design very much like this, before evolving it into the cellular "Waffle hab" I presented in my first post. https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641
This shows how easily some us (me) forget preceding posts in this very long thread. Your idea was excellent and could be an advanced phase of the "enhanced trench" approach.

Thanks, as are your ideas. I should acknowledge here that these are very different design spaces (reusing Starship on Mars vs purpose-built structures), but the possibility of parallel design evolution is tantalizing.

Step 2: A row of buried horizontal cylinders. Closer together is better to avoid wasting regolith and minimize connecting tunnel mass, concentrating shielding mass on the roof. Analogous to your "enhanced trench." The expanding foam sheath becomes a foam footer (similar to an ICF on Earth), and the interstitial regolith is maintained at room temperature, acting as a thermal battery.

OK, except the part of foam touching SS surface would be room temp and the part touching regolith would be cryogenic cold.

The footer insulates the structure and the warm regolith (thermal battery) from the cold regolith underneath.


Step 4: Simplify. Why do we have all this extra regolith in between the cylinders? Delete it (keeping the shielding/thermal regolith roof and walls of course), saving both structural mass and labor on Mars. This also deletes the mass of the connecting tunnels between cylinders, simplifying them down to just a single pressure isolation door (vs the the tunnel which needs two such doors). At this point you also rearrange the pressure vessel shape from a hexgrid of cylinders to a rectilinear grid of walls or beams. This not only saves structural mass, it also "packs" the interior space far better than a cylinder shape (cylinders always end up with awkward corners).

Here is where you need the hard material between cylinders to act as pillars in compression for the next row of cylinders above. Otherwise you will need to import steel beams from Earth for this purpose.

At Step 4 they're no longer "rows of cylinders" at all. The same rigid beams that carry the pressure vessel tension also carry compression loads in a contingency depressurization. For an inflatable design your contingency load is carried by tensile wrapped Marscrete suspension towers, but I think in the long term you just make the pressure maintenance highly reliable (which is needed anyway) and delete the towers (just like Starship deleting LAS in favor of "just make it reliable").


Because this is a step more complex, I would suggest holding the vertical phase of development to a later time when more equipment is available. For the first phase of Mars development, lining up SS cylinders on one level would be easier.

That's the beautiful part though, it doesn't need large amounts of equipment. Just inflate, bury, and occupy. Burying is the hardest part, but as outlined this requires less earthmoving marsmoving per unit of pressurized volume than trenching and burying Starships.

For a fraction of a single SS payload mass, you can have as much volume as cannibalizing a dozen Starships, all while consuming far less assembly labor (vs connecting Starships together with tunnel modules).

Elon isn't known for dragging his feet. "If it's tight it's right, if it's long it's wrong." Therefore I predict at most one or two buried Starships in Phase 1 (10-30 people), followed by Phase 2 using lightweight pre-fab (ideally Waffle) habitats. These shielded habs would house the tele-workers and maintenance staff (100-300 people) who work on Phase 3 (digging large scale underground habitation suitable for 1000+ people), as well as being used for quick/cheap research outposts and mining shacks.

This is the fastest way to ramp. Waiting for Starships to accumulate at Phase 1 is far too slow, since it unnaturally limits the growth of pressurized volume.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Genial Precis on 10/15/2019 01:11 am
Apropos of nothing, let me offer a construction material in search of a problem to solve: mineral fiber reinforced water ice. If there's a low-footprint way to make something like basalt fibers and you have somewhat plentiful water, stir chopped fibers into water and either cast blocks or possibly spray in place. If it has vaguely concrete-ish properties you'd have a decent structural/shielding material, that you could pile up high and have it be self-supporting.

That said, it clearly fills a similar niche as concrete. Could anyone explain the prospects for a cement that would work well on Mars? I don't imagine that the hydration reactions of portland cement work at all at such low temperatures, is that correct?

One thing that is on my mind is that low-embodied energy materials seem useful, depending on how much energy scarcity limits early activities versus other scarce resources.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/15/2019 04:05 am
Because moving a pile of dirt is going to be the major expense.
Not sure if this is supposed to be sarcasm. It's a major expense, yes.

The cost of earth moving is trivial compared to anything you do to reduce the amount of earth needing to be moved. Hence, for a Mars settlement, earth-moving should not be on the list of things you need to minimise. Because the only time it actually helps to minimise it, it'll be because of a cost unrelated to the actual moving of earth.

I see this argument from you and other people trying to cut down on the volume of regolith by suggesting containment (bags, sintered blocks, complex shield material, etc), as if a pile of dirt is somehow so expensive or complex that a manufactured process that reduces the regolith volume by 40-60% is worthwhile.
Sorry, you must have me confused with someone else.  I'm the "just pile regolith on your hab" guy.

...immediately followed by...

For the walls it's possible that eg HESCO Bastions would save some cost, but I've always maintained that the final solution is a cost-optimal combination of a gravity bank and a reinforced Earth regolith wall.

Retaining walls, especially reinforced retaining walls, are more expensive than piles of dirt. Unless there's an external cost, such as interference with existing infrastructure, access clearances, etc. In a greenfield site, which applies to any early Mars settlement, anything other than piles of dirt is choosing a more "expensive" (parts, equipment, labour, time, etc) option.



Changing gears and moving indoors...

[waffle hab]
The same rigid beams that carry the pressure vessel tension also carry compression loads in a contingency depressurization. For an inflatable design your contingency load is carried by tensile wrapped Marscrete suspension towers,

If they are composite overwrapped, do they need to be Marscrete? Would compacted dirt handle enough compression (without increasing their width too much), if the sidewall-bursting tensile forces were taken up by the composite overwrap?

On Dirt Earth, internally reinforced concrete gives a nice consistent material at a lower cost than composite-overwrapping. But it's likely that the quality of Marscrete will be pretty inconsistent, at least for its first few iterations, which means you have to assume it's not much better than the material it's made of. So why not cut out the middle-man and just fill hollow cylindrical tensile columns with regolith. It'll mean the fibre direction has to also run horizontal, not just vertical, but the additional weight of fibre should be fairly trivial.

(IIRC, you have access to decent FEA software. If you assume a good composite overwrap, how much does compacted "soil" widen the needed columns for the same compressive strength? How much more composite is required?)

Also... If the columns were unpressurised, open at the top, with airtight walls isolated from the rest of the inside of the hab, would compacted regolith fill be able to handle the crush-pressure from the air pressure in the hab on the column walls, without buckling?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/15/2019 05:26 am
Because moving a pile of dirt is going to be the major expense.
Not sure if this is supposed to be sarcasm. It's a major expense, yes.

The cost of earth moving is trivial compared to anything you do to reduce the amount of earth needing to be moved. Hence, for a Mars settlement, earth-moving should not be on the list of things you need to minimise. Because the only time it actually helps to minimise it, it'll be because of a cost unrelated to the actual moving of earth.

I see this argument from you and other people trying to cut down on the volume of regolith by suggesting containment (bags, sintered blocks, complex shield material, etc), as if a pile of dirt is somehow so expensive or complex that a manufactured process that reduces the regolith volume by 40-60% is worthwhile.
Sorry, you must have me confused with someone else.  I'm the "just pile regolith on your hab" guy.

...immediately followed by...

For the walls it's possible that eg HESCO Bastions would save some cost, but I've always maintained that the final solution is a cost-optimal combination of a gravity bank and a reinforced Earth regolith wall.

Retaining walls, especially reinforced retaining walls, are more expensive than piles of dirt. Unless there's an external cost, such as interference with existing infrastructure, access clearances, etc. In a greenfield site, which applies to any early Mars settlement, anything other than piles of dirt is choosing a more "expensive" (parts, equipment, labour, time, etc) option.

It sounds like we agree on all major points.

Obviously you have some very strong opinions on what the cost-optimal solution looks like, and that's fine. :) It takes away nothing from what I said. Simply choose the "cost-optimal combination" for you (presumably 100% gravity bank and 0% reinforced regolith) and proceed to the next decision.

But if for some reason you wanted to build a 100 story skyscraper, you probably shouldn't choose 100% gravity bank for the wall shielding. ;) Every situation is different. Thats why I speak in terms of trade-off decisions, not hard-and-fast rules.

Changing gears and moving indoors...

[waffle hab]
The same rigid beams that carry the pressure vessel tension also carry compression loads in a contingency depressurization. For an inflatable design your contingency load is carried by tensile wrapped Marscrete suspension towers,

If they are composite overwrapped, do they need to be Marscrete? Would compacted dirt handle enough compression (without increasing their width too much), if the sidewall-bursting tensile forces were taken up by the composite overwrap?

Yes, by "Marscrete" I'm assuming sulfur-bound compressed regolith. Sorry for the (no doubt) horrible abuse of terminology.

On Dirt Earth, internally reinforced concrete gives a nice consistent material at a lower cost than composite-overwrapping. But it's likely that the quality of Marscrete will be pretty inconsistent, at least for its first few iterations, which means you have to assume it's not much better than the material it's made of. So why not cut out the middle-man and just fill hollow cylindrical tensile columns with regolith. It'll mean the fibre direction has to also run horizontal, not just vertical, but the additional weight of fibre should be fairly trivial.


(IIRC, you have access to decent FEA software. If you assume a good composite overwrap, how much does compacted "soil" widen the needed columns for the same compressive strength? How much more composite is required?)

Yes, it sounds like we're thinking along exactly the same lines. I was picturing conical sections, nested for transport and connected together on Mars. Ram sifted regolith inside to prevent buckling and augment the compressive strength. Just the composite cylinder might be enough though...

Also... If the columns were unpressurised, open at the top, with airtight walls isolated from the rest of the inside of the hab, would compacted regolith fill be able to handle the crush-pressure from the air pressure in the hab on the column walls, without buckling?

Iirc the ram pressures for forming sulfur-bound Marscrete were in the megapascals, far exceeding the crush pressure here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/15/2019 04:03 pm
Village Trench Layout
Phase 2 10-15-19

Continuing from the enhanced trench (Reply #2586) for Starships lying in horizontal position. Also continuing the initial layout of trenches for the first landing of humans (Reply #2598).

Phase 2 could be the second landing that brings two passenger SSs and additional cargo SSs. Passenger vehicles may be utilized in vertical position or laid in horizontal position and covered with an arch of block ice for GCR radiation protection. After unloading, pressurized cargo SS may also be converted to use as habitats or other human occupancy. All pressurized payload or crew sections would be joined to their respective CH4 and LOX tanks to greatly expand habitable volume.

The sketch below shows a possible layout for trenches in Phase 2. It is intended to accommodate Starships landed during the first two synods and incorporate them into a hallway system for a growing village. As indicated, all SSs are designed for a particular purpose stated on the sketch.

Edit: spelling
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/15/2019 04:23 pm
In the sketch above I borrowed Twark_Main’s idea of compact arrangement. The horizontal SSs lie closer together, leaving only 1m of hard ground on each side as a base for a 1m ice block arch over each vessel.

An arrow points down the hallway to “Other Amazing Martian Habitats.” This is my appreciation for the many excellent designs suggested in this thread that could be attached to this initial pioneer village.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/15/2019 05:39 pm
Village Trench Layout
Phase 2 10-15-19

Continuing from the enhanced trench (Reply #2586) for Starships lying in horizontal position. Also continuing the initial layout of trenches for the first landing of humans (Reply #2598).

Phase 2 could be the second landing that brings two passenger SSs and additional cargo SSs. Passenger vehicles may be utilized in vertical position or laid in horizontal position and covered with an arch of block ice for GCR radiation protection. After unloading, pressurized cargo SS may also be converted to use as habitats or other human occupancy. All pressurized payload or crew sections would be joined to their respective CH4 and LOX tanks to greatly expand habitable volume.

The sketch below shows a possible layout for trenches in Phase 2. It is intended to accommodate Starships landed during the first two synods and incorporate them into a hallway system for a growing village. As indicated, all SSs are designed for a particular purpose stated on the sketch.

Edit: spelling


Yup, we see this sort of arrangement in one of the previous SpaceX Mars City videos.

Of course, these would probably be buried with regolith; they just look prettier on the surface. I doubt that they have gone much further than sketch-level designs with their habitats and bases... these are of course just pretty pictures for media.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/15/2019 06:46 pm
...
...
Yup, we see this sort of arrangement in one of the previous SpaceX Mars City videos.

Of course, these would probably be buried with regolith; they just look prettier on the surface. I doubt that they have gone much further than sketch-level designs with their habitats and bases... these are of course just pretty pictures for media.
Well, i'm glad they got it right.  ;D
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/15/2019 09:13 pm
I'm the "Tunnel guy" in this thread, as some of you know by now, but for the sake of argument I would suggest to cut the Starship in half, lengthwise, before laying it down as a horizontal hab. It would make a couple of nice Nissen huts and it could be plopped right down on a flat plot of land.

I imagine an inflatable bladder as the inside lining, standing off a few inches from the ground and steel skin, which would provide vacuum insulation similar to a double-pane window glass. Piling regolith on top of the hut would be easier due to the lower height. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/16/2019 01:53 am
for the sake of argument I would suggest to cut the Starship in half, lengthwise, before laying it down as a horizontal hab. It would make a couple of nice Nissen huts and it could be plopped right down on a flat plot of land.
I imagine an inflatable bladder as the inside lining, standing off a few inches from the ground and steel skin [...]

The pressure vessel (bladder) would be rounded in vertical cross section, unless you add a lot of internal or external anchoring to hold it in a weird shape to match the semi-cylindrical half-shell. Without such weirdness, you lose a lot of volume in the half-shells.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/16/2019 02:39 am
by "Marscrete" I'm assuming sulfur-bound compressed regolith. Sorry for the (no doubt) horrible abuse of terminology.

I got the reference. I was comparing to regolith without any chemical binding. At extreme, picture dry sand. Does the column still work as intended?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/16/2019 03:48 am
by "Marscrete" I'm assuming sulfur-bound compressed regolith. Sorry for the (no doubt) horrible abuse of terminology.

I got the reference. I was comparing to regolith without any chemical binding. At extreme, picture dry sand. Does the column still work as intended?

Well compacted sand would stabilize it in th buckling mode, so presumably it would contribute to strength if you designed the tower cylinders as buckling critical structures. Obviously not as strong as Marscrete, but potentially stronger than hollow tubes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ChrisPhoenix on 10/16/2019 06:42 am
I read the point about regolith-covered habs needing to deal with deflation, but I do not agree with it.

Accidental deflation is a life-threatening event, with or without cover dust. It should never happen. Engineer so that it won't.

In fact, in a slow leak scenario, a rigid hab will lose pressure, while a flexible hab supporting dust will retain pressure but lose volume. You might have to crawl, but you'll have more time to escape.

Planned deflation should not be required frequently, and perhaps not at all. Any structure has a service lifetime. Given the pace of engineering and settlement, early Mars habs that are acceptably reliable will probably have a service lifetime of at least decades without deflation - which is longer than they will be needed. Plastic under dry dust should have quite a long lifespan.

If you do need to plan for deflation, then you can always scrape the cover dirt away, as easily as you put it on.

A couple of meters of dust has a pretty good insulation value. The internal waste heat from using the hab should be able to keep it nice and warm. Another advantage is thermal mass, to average out the Martian daily temperature swings.

On a related topic, would someone please confirm whether I'm right that Martian regolith can be moved from point to point simply by throwing it? In thin atmosphere and low gravity, it shouldn't disperse much even over hundreds of feet/meters, and it doesn't take much energy to propel it. (I've done the math on that, but this post is already too long.)

So Twark_Main may be the "just pile regolith on your hab" guy, but I'm even more so. No rigid structure needed at all! None! Not shipped from Earth, not built on-site. A very thin pressure envelope; enough tensile material to keep the envelope from popping (and give the hab a flattish shape); a "snow thrower" that can drive around, scrape up dust, and toss it onto the hab - and you're home!

You might also want:
* Floors that are flat and protect the pressure envelope
* A final bit of insulation with a vapor barrier, to keep humidity from condensing on the pressure membrane
* Dogleg tubes with mirrors, to let light in but keep radiation out
* Airlocks (OK, you actually need airlocks)
* Expansion kits that can attach more volume to your hab without deflating it (yes, this is straightforward if you design for it)
* Lighting, climate control, furniture
* Maybe an outer layer of special plastic to resist whatever chemicals are in the dust
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/16/2019 11:00 am
for the sake of argument I would suggest to cut the Starship in half, lengthwise, before laying it down as a horizontal hab. It would make a couple of nice Nissen huts and it could be plopped right down on a flat plot of land.
I imagine an inflatable bladder as the inside lining, standing off a few inches from the ground and steel skin [...]

The pressure vessel (bladder) would be rounded in vertical cross section, unless you add a lot of internal or external anchoring to hold it in a weird shape to match the semi-cylindrical half-shell. Without such weirdness, you lose a lot of volume in the half-shells.

Hmm, the pressure bladder can be in any shape it is sown into.. - See all sorts of bouncing castles and inflatable tennis courts.

Still would prefer several meters of regolith around and especially above me.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/16/2019 12:32 pm
for the sake of argument I would suggest to cut the Starship in half, lengthwise, before laying it down as a horizontal hab. It would make a couple of nice Nissen huts and it could be plopped right down on a flat plot of land.
I imagine an inflatable bladder as the inside lining, standing off a few inches from the ground and steel skin [...]
The pressure vessel (bladder) would be rounded in vertical cross section, unless you add a lot of internal or external anchoring to hold it in a weird shape to match the semi-cylindrical half-shell. Without such weirdness, you lose a lot of volume in the half-shells.
Hmm, the pressure bladder can be in any shape it is sown into.. - See all sorts of bouncing castles and inflatable tennis courts.

Have a look at the shapes of the actual pressurised parts. (Also the (low) pressure they are usually inflated to.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/16/2019 04:32 pm
I read the point about regolith-covered habs needing to deal with deflation, but I do not agree with it.

Accidental deflation is a life-threatening event, with or without cover dust. It should never happen. Engineer so that it won't.

In fact, in a slow leak scenario, a rigid hab will lose pressure, while a flexible hab supporting dust will retain pressure but lose volume. You might have to crawl, but you'll have more time to escape.

Planned deflation should not be required frequently, and perhaps not at all. Any structure has a service lifetime. Given the pace of engineering and settlement, early Mars habs that are acceptably reliable will probably have a service lifetime of at least decades without deflation - which is longer than they will be needed. Plastic under dry dust should have quite a long lifespan.

If you do need to plan for deflation, then you can always scrape the cover dirt away, as easily as you put it on.

A couple of meters of dust has a pretty good insulation value. The internal waste heat from using the hab should be able to keep it nice and warm. Another advantage is thermal mass, to average out the Martian daily temperature swings.

On a related topic, would someone please confirm whether I'm right that Martian regolith can be moved from point to point simply by throwing it? In thin atmosphere and low gravity, it shouldn't disperse much even over hundreds of feet/meters, and it doesn't take much energy to propel it. (I've done the math on that, but this post is already too long.)

So Twark_Main may be the "just pile regolith on your hab" guy, but I'm even more so. No rigid structure needed at all! None! Not shipped from Earth, not built on-site. A very thin pressure envelope; enough tensile material to keep the envelope from popping (and give the hab a flattish shape); a "snow thrower" that can drive around, scrape up dust, and toss it onto the hab - and you're home!

Perhaps not so different from my proposal :D (right down to using the regolith shield as a thermal mass). I guess you didn't see this part, where I talk about an inflatable hab:

Step 4: Simplify. Why do we have all this extra regolith in between the cylinders? Delete it (keeping the shielding/thermal regolith roof and walls of course), saving both structural mass and labor on Mars. This also deletes the mass of the connecting tunnels between cylinders, simplifying them down to just a single pressure isolation door (vs the the tunnel which needs two such doors). At this point you also rearrange the pressure vessel shape from a hexgrid of cylinders to a rectilinear grid of walls or beams. This not only saves structural mass, it also "packs" the interior space far better than a cylinder shape (cylinders always end up with awkward corners).

Here is where you need the hard material between cylinders to act as pillars in compression for the next row of cylinders above. Otherwise you will need to import steel beams from Earth for this purpose.

At Step 4 they're no longer "rows of cylinders" at all. The same rigid beams that carry the pressure vessel tension also carry compression loads in a contingency depressurization. For an inflatable design your contingency load is carried by tensile wrapped Marscrete suspension towers, but I think in the long term you just make the pressure maintenance highly reliable (which is needed anyway) and delete the towers (just like Starship deleting LAS in favor of "just make it reliable").



You might also want:
* Floors that are flat and protect the pressure envelope

As I pointed out in my first post, you can have flat tensile floors in an inflatable. You'll need a cover layer to protect it from wear, but you don't need a separate structural floor. Image is attached.

* A final bit of insulation with a vapor barrier, to keep humidity from condensing on the pressure membrane

You'll need insulation anyway, since regolith doesn't actually make a great insulating layer (thermal mass yes, insulation no). But if you put the thermal insulation outside the regolith instead, it will equalize to the interior temperature.

* Dogleg tubes with mirrors, to let light in but keep radiation out

Light tubes are nice. You can delete the entire "tube" part and it still works too. Just position mirrors outside your hab and bounce sunlight in horizontally beneath an overhang.

* Airlocks (OK, you actually need airlocks)
* Expansion kits that can attach more volume to your hab without deflating it (yes, this is straightforward if you design for it)

Presumably these would use a common hatch design.

* Lighting, climate control, furniture

Film ducts seem reasonable for climate control, since they can be pre-installed then packed flat inside the inflatable.

* Maybe an outer layer of special plastic to resist whatever chemicals are in the dust

And whatever chemicals come off the humans and their greenhouses! ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: spaced42 on 10/16/2019 06:38 pm
for the sake of argument I would suggest to cut the Starship in half, lengthwise, before laying it down as a horizontal hab. It would make a couple of nice Nissen huts and it could be plopped right down on a flat plot of land.
I imagine an inflatable bladder as the inside lining, standing off a few inches from the ground and steel skin [...]

The pressure vessel (bladder) would be rounded in vertical cross section, unless you add a lot of internal or external anchoring to hold it in a weird shape to match the semi-cylindrical half-shell. Without such weirdness, you lose a lot of volume in the half-shells.

I don't post often, but this design really caught my interest.  It's simple and is already optimized to support the weight of regolith/ice/insulating material.

However, why go thru the trouble of disassembling a SS when something as simple as Quonset huts could be shipped and assembled which are much more lightweight and customizable?  For a small fraction of a SS's cargo space you could probably achieve a much higher usable volume of space in the end.  And you would still have a SS for return or other purposes.

(for an example of quonset hut simplicity you can so a quick google search)

But I love the idea of a bladder or pressure vessel that would fill the space.  Just clear out the space underneath of rocks, grade it flat, then use a inflating hab with a semi-rigid floor and a fairly simple expanding ceiling that would press up against the interior for stability. 

For more advanced versions, you could line up several in rows, fill the space between with regolith, then stack another in a staggered fashion.  Voila, pyramids on mars! 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/16/2019 10:00 pm
...It's true that if the corrugated steel plates are cut to fit out the cargo hatch then Nissen huts would be a quite practical design, both for compactness during the trip to Mars and ease of assembly on the surface. The half-cylinder would also be an optimal shape for piling regolith on top.

Hehe... Perhaps this tried and true design will end up being multiplanetary.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/16/2019 10:04 pm
Expanding SS habitat volume
Continued from Replies 2586, 2598, 2602.

From the 2019 update, the volume of passenger Starship is 1000 m3. After landing on Mars, what would be the significance of expanding this volume to include LOX and CH4 tanks as living space.?

I couldn’t find these volume data, but I did see the mass of propellant is 1200t. I estimated tank volume by using data from  Wikipedia, which listed densities of LOX and LCH4 as 1.141 and 0.423 kg/l respectively. From livingJW on NSF I found  the fuel to oxygen to fuel ratio for Raptor engines is 3.6 to 1. I calculated tank volumes to be about 647 m3 and 617 m3 respectively, or 1265 m3 total. Therefore, the proposed cutting and welding operation would expand livable volume of each SS from 1000 m3 to 2265 m3, or 127 percent.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/16/2019 10:06 pm
Expanding SS habitat volume (continued)

Initial landings on Mars are planned to carry between 12 and 24 crew members. For a crew of 12, (theoretical) living space would expand from 83 to 188 m3 per person. For a crew of 24, space would expand from 47 to 94 m3 per person.

In addition, each cargo ship with a pressurized cargo bay could be converted to an additional 2265 m3 of living space. These converted SS would be particularly useful when laid in horizontal position as greenhouses.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/16/2019 10:07 pm
Expanding SS habitat volume - ECLSS

To become living space, the extra volume in propellant tanks must be supplied with clean breathable air. For the trip to Mars, an ECLSS unit must be installed in the passenger section. A second ECLSS unit of the same or larger capacity could be placed in the auxiliary cargo area, also inside the passenger section. It would be the backup unit for the interplanetary journey. Upon arrival at the settlement, crew could redirect ductwork into the expanded living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/17/2019 04:04 am
But I love the idea of a bladder or pressure vessel that would fill the space.  Just clear out the space underneath of rocks, grade it flat, then use a inflating hab with a semi-rigid floor and a fairly simple expanding ceiling that would press up against the interior for stability.

...It's true that if the corrugated steel plates are cut to fit out the cargo hatch then Nissen huts would be a quite practical design, both for compactness during the trip to Mars and ease of assembly on the surface. The half-cylinder would also be an optimal shape for piling regolith on top.

Hehe... Perhaps this tried and true design will end up being multiplanetary.


Oh no, here we go again...  :o

The problem is, you'll have enormous pressure forces pushing up on the Quonset hut walls, because of the flat floor. You'd need huge heavy rock anchors to resist the pressure forces, and we've been down that road before. TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.

For more advanced versions, you could line up several in rows, fill the space between with regolith, then stack another in a staggered fashion.  Voila, pyramids on mars!

Agreed. Sounds similar to "design evolution Step 3," except I use full cylinders. In Step 4 the (unnecessary) fill regolith is deleted, instead moving all regolith to the outermost roof/walls where it can do the most good.

https://forum.nasaspaceflight.com/index.php?topic=41427.msg2004737#msg2004737
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/17/2019 07:03 am
Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.

Even without the top-weight, there's presumably an optimally squashed oblate spheroid (or oblate cylinder) that maximises usable floor-space, while minimising internal cross-linking and envelope mass.

[Also, if you are using ISRU materials (rather than Earth-shipped or... ships), there might be some benefit to having an unpressurised load-bearing shell around a pressurised module, where you have not just a few inches of Mars-ambient for insulation, but several feet for simply EVA maintenance and to run shared utilities between modules. (Running utilities internally through standard hatches is bulky and interferes with their value as emergency bulkheads.)]

TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Keep fighting the good fight, Sir.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/17/2019 07:13 am
...It's true that if the corrugated steel plates are cut to fit out the cargo hatch then Nissen huts would be a quite practical design, both for compactness during the trip to Mars and ease of assembly on the surface. The half-cylinder would also be an optimal shape for piling regolith on top.

Hehe... Perhaps this tried and true design will end up being multiplanetary.


Oh no, here we go again...  :o

The problem is, you'll have enormous pressure forces pushing up on the Quonset hut walls, because of the flat floor. You'd need huge heavy rock anchors to resist the pressure forces, and we've been down that road before. TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.


You've become increasingly snarky in the last couple of months. Perhaps frustration with those of a perceived lesser intellect?

The Nissen huts would of course, as mentioned above, have lots of regolith piled on top. That would be the 'rock anchor'.

The half-cylindrical shape would be optimal for - as I wrote - compactness during the trip and ease of assembly on the surface. Sure, an oblate spheroid is the theoretically best shape when actually deployed, but the other factors are very important as well. You have to look at the totality of transport, assembly and use. SpaceX has shown a huge propensity towards practical solutions instead of optimising for the last 3 percent. That's their whole ethos, you could say.

Nissen huts on the surface would be a quick and practical solution for rapid habs and work-shops while drilling the underground tunnels gets underway. The frames and plates (carbon fibre or metal) of the huts could later be reused for tunnel reinforcement if needed.   
Title: Re: Envisioning Amazing Martian Habitats
Post by: ChrisPhoenix on 10/17/2019 07:47 am
For an inflatable design your contingency load is carried by tensile wrapped Marscrete suspension towers, but I think in the long term you just make the pressure maintenance highly reliable (which is needed anyway) and delete the towers (just like Starship deleting LAS in favor of "just make it reliable").

I read "inflatable" and "towers" but I didn't notice "delete the towers." I'm inclined to think you need enough reliability right from the start, and you accept enough risk especially at the start, that you never need the towers, and you can have your nice big convenient habs starting with the very first landing.

As I pointed out in my first post, you can have flat tensile floors in an inflatable. You'll need a cover layer to protect it from wear, but you don't need a separate structural floor. Image is attached.

Nice! I've been picturing a single story, something like an air mattress, and I hadn't thought of the tensile-floor trick.

Of course if you're hanging lots of floors and their load from the roof, like in your design, you don't get to pile on as much regolith. I'm reasonably comfortable with the radiation (and thermal) shielding you get from 5 PSI / 33 kPA of regolith, but I wouldn't necessarily want to cut that in half.

You'll need insulation anyway, since regolith doesn't actually make a great insulating layer (thermal mass yes, insulation no). But if you put the thermal insulation outside the regolith instead, it will equalize to the interior temperature.

A little Google searching says that packed terrestrial dirt has an R value of 0.125-0.25 per inch and brick is 0.8 per 4 inches. So 2 meters of loose dry regolith should have an I-P R value of 10-20 or better. Let's be pessimistic and say 100 K temperature difference and R value of 10 (~1.7 SI). Then you only lose ~60 W per square meter, unless I'm making a really silly math error. If each person needs 10 kW of power, they need about 170 square meters to conduct the waste heat away. Fully inflatable habs are cheap, but I doubt people will have that much space apiece.

Light tubes are nice. You can delete the entire "tube" part and it still works too. Just position mirrors outside your hab and bounce sunlight in horizontally beneath an overhang.

Overhang has to support regolith. That's actual construction work. It'll come down to whatever is easier to ship, assemble, and place.

* Airlocks (OK, you actually need airlocks)
* Expansion kits that can attach more volume to your hab without deflating it (yes, this is straightforward if you design for it)

Presumably these would use a common hatch design.

I was picturing something bigger than a hatch - attach an inflated tube to the outside of a wall, then cut away the wall.

Film ducts seem reasonable for climate control, since they can be pre-installed then packed flat inside the inflatable.

Machinery for heating, cooling, dehumidifying, gas chemistry control... Also, some ducts need to suck (though I suppose you could run wires to power fans at each inlet).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 10/17/2019 08:45 am
Limiting thinking about habitat construction to regolith, ice and materials from Earth is too restrictive.

Has anyone thought about how we might be able to make cement (concrete) on Mars, based on minerals or rocks known to be available? Not the "Marscrete" mentioned up-thread, but something closer to Portland cement (plus sand and aggregate) or perhaps Roman concrete. It's one of the most widely used building materials on Earth, and seems like it would be immensely useful on Mars, too.

One possibility might be to use volcanic ash as a starting point, if a deposit can be found.

I've read that phyllosilicates to make clay are indeed available, which, by itself, would also be an extremely useful building material.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/17/2019 10:35 am
The Nissen huts would of course, as mentioned above, have lots of regolith piled on top. That would be the 'rock anchor'.

At 10 tonnes-force of air pressure per square metre, you need about 15m of regolith to balance the air pressure. You'll need to shape this so that the load is also against the sloping walls with the correct sideways force, otherwise the structure will still deform.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/17/2019 11:28 am
...And in case of a leak and loss of air pressure the hab would obviously be crushed under the weight of that mountain of regolith...

- Yup, more than ever I'm convinced that tunnels are the way to go... - And of course Elon said the same in a Reddit AMA all the way back in 2016:

https://www.reddit.com/r/spacex/comments/590wi9/i_am_elon_musk_ask_me_anything_about_becoming_a/d94rj0s/

Q: Ulysius
As a follow-up, considering the synodal reuse of the ITS spaceships, what form of permanent habitation do you foresee? Shipped modules or an (eventual) shift to in-situ resource utilization such as Martian rigolith/plastic-reinforced concrete structures?
Thank you for your time.


A: ElonMuskOfficial
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/17/2019 12:39 pm
...And in case of a leak and loss of air pressure the hab would obviously be crushed under the weight of that mountain of regolith...

- Yup, more than ever I'm convinced that tunnels are the way to go... - And of course Elon said the same in a Reddit AMA all the way back in 2016:

https://www.reddit.com/r/spacex/comments/590wi9/i_am_elon_musk_ask_me_anything_about_becoming_a/d94rj0s/

Q: Ulysius
As a follow-up, considering the synodal reuse of the ITS spaceships, what form of permanent habitation do you foresee? Shipped modules or an (eventual) shift to in-situ resource utilization such as Martian rigolith/plastic-reinforced concrete structures?
Thank you for your time.


A: ElonMuskOfficial
Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.


Pressurised space for industrial operations is not a habitat.

Part of my old job involved drilling into rock and pressure testing them at several bar (not me personally, I looked at the data from a comfy office). Drilled holes always have fractures (something else I learned from spending far too long of my career looking at borehole wall rock).

Unless the rocks also have tight pore spaces, they will not hold air either. Most sedimentary rocks are extremely porous, so it has to be extremely competent igneous rock: basically, granite or a very non-porous basalt (varies widely). And these are hard to drill through because it is not porous and full of fractures. The alternative is to use a moving shield TBM to tunnel through loose, fractured rock and place tunnel liners as it goes. For the most majority of foreseeable geotechnical conditions, fracture sealing will be required. My question is why bother with a TBM when you can simply drop a 9m shaft sinker straight down, then once you have sufficient depth, pull it up to go across and make another shaft.

If people want to propose a colony made of up 2m diameter tunnels drilled by mini TBMs, then go for it. I am saying that it is not practical: it requires a combination of geological good luck and a lot of equipment to provide a service (putting matter overhead) achievable by other, simpler means.
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 10/17/2019 01:37 pm
Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.

Even without the top-weight, there's presumably an optimally squashed oblate spheroid (or oblate cylinder) that maximises usable floor-space, while minimising internal cross-linking and envelope mass.

[Also, if you are using ISRU materials (rather than Earth-shipped or... ships), there might be some benefit to having an unpressurised load-bearing shell around a pressurised module, where you have not just a few inches of Mars-ambient for insulation, but several feet for simply EVA maintenance and to run shared utilities between modules. (Running utilities internally through standard hatches is bulky and interferes with their value as emergency bulkheads.)]

TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Keep fighting the good fight, Sir.

O.K., so this talk of oblate spheroids and combining a load bearing structure with an inflatable gives me the push to finally expose an idea for a Mars habitat that I've had for several years.  Feedback welcome, but try to be gentle :-) 

The great advantage of an inflatable is obviously the great increase in usable volume between the deployed hab versus the shipped hab.  But the disadvantages are lack flat floors, and generally no 'structural integrity' to transmit floor, wall, equipment, etc. forces to terra firma (Mara firma?)  Likewise geodesic structures are great from a structural integrity standpoint, but require a large construction effort (compared to inflatables), which is magnified when it has to be done by folks in spacesuits. 

So why not combine the two ideas?  Have an inflatable oblate spheroid, which has an internal geodesic skeleton.  (See attached pic).  A key idea here is to have the geodesic 'hard points' (the nodes) poke through the inflatable membrane at several (all?) node points.  That allows the structure as a whole to anchored (via pylons) into the regolith, and also allows for attachment points topside for some lightweight aluminum panels, upon which a few meters of regolith can be placed.  Thus the structure will not cave in if pressure is lost, or needs to be evacuated for some reason.

A second key to this is to have the geodesic structure itself be designed in such a way that it can be shipped in a 'collapsed' state, which 'unfolds' when the membrane is inflated.  That is, the entire structure (membrane and geodesic) will be constructed, integrated and tested Earthside before being collapsed into a small unit for shipment.  And on Mars surface simply inflating the membrane will cause the geodesic skeleton to gently unfold into place.

The way I envision this is to have each 'strut' of the structure actually be a hinged 'W' shape, and the W folds inward for shipment.  (Struts will have a rectangular cross section.)  The struts will also be hinged where they connect to the hubs.  The hinges of course must be quite robust, and there should be a positive locking mechanism at each hinge point when the structure unfolds.  This could theoretically be done with a strong magnet at each hinge point, which pulls the two members into exact alignment whereupon a latch engages.  Or there could be an additional, 'empty hinge' on the opposite side of each hinge, which the colonists then push into alignment and slide in a pin.

Anyway, once the structure is inflated and an airlock is attached, crew would descend into it and begin attaching 'floor joists' to the hard points (nodes), and then lay on floor panels.  Working their way up from bottom to top.  Model shown also has 6 structural poles attached to 6 lowest nodes, for support of floor joists.

I see a nominal design (shown) being about 10 meters tall and 13.33 meters in diameter.  With 3 layers:  'Basement' for storage, Mid layer for private quarters (probably dual occupancy), and top 'open space' for communal living.  Should be able to house ~20 colonists in relative comfort, akin to college dorm style living.

Top floor would be about 1 meter above local grade, which implies a 'divot' about 4 meters deep would have to be excavated.  Maybe somewhat less if a natural dip in the landscape is chosen.  Excavated material can be used later for regolith cover over the structure.

Above all I see the advantage of this to be a very rapid deployment of living space, which colonists could envision living in for decades.  What do you think?
 

Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/17/2019 03:57 pm
Limiting thinking about habitat construction to regolith, ice and materials from Earth is too restrictive.

Has anyone thought about how we might be able to make cement (concrete) on Mars, based on minerals or rocks known to be available? Not the "Marscrete" mentioned up-thread, but something closer to Portland cement (plus sand and aggregate) or perhaps Roman concrete. It's one of the most widely used building materials on Earth, and seems like it would be immensely useful on Mars, too.
...
...
Yes, a number of research projects have addressed this question.

The principal problem is that the common concretes on Earth use water as a solute. When mixed with sand, rocks, and water, Portland cement undergo a chemical reaction (not just drying) to transform the mixture into concrete. This occurs over a number of hours or days. On Mars’ surface, water exposed to 0.5 psi ambient air immediately sublimates, which prevents the cement hardening process to proceed to completion.

I first looked into the problem in 2013 when I was writing articles for The Mars Pioneers website. I found that resins may offer a better approach, as some of them are less volatile with a longer hardening time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/17/2019 06:20 pm
Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.

Even without the top-weight, there's presumably an optimally squashed oblate spheroid (or oblate cylinder) that maximises usable floor-space, while minimising internal cross-linking and envelope mass.

[Also, if you are using ISRU materials (rather than Earth-shipped or... ships), there might be some benefit to having an unpressurised load-bearing shell around a pressurised module, where you have not just a few inches of Mars-ambient for insulation, but several feet for simply EVA maintenance and to run shared utilities between modules. (Running utilities internally through standard hatches is bulky and interferes with their value as emergency bulkheads.)]

TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Keep fighting the good fight, Sir.

O.K., so this talk of oblate spheroids and combining a load bearing structure with an inflatable gives me the push to finally expose an idea for a Mars habitat that I've had for several years.  Feedback welcome, but try to be gentle :-) 

The great advantage of an inflatable is obviously the great increase in usable volume between the deployed hab versus the shipped hab.  But the disadvantages are lack flat floors, and generally no 'structural integrity' to transmit floor, wall, equipment, etc. forces to terra firma (Mara firma?)  Likewise geodesic structures are great from a structural integrity standpoint, but require a large construction effort (compared to inflatables), which is magnified when it has to be done by folks in spacesuits. 

So why not combine the two ideas?  Have an inflatable oblate spheroid, which has an internal geodesic skeleton.  (See attached pic).  A key idea here is to have the geodesic 'hard points' (the nodes) poke through the inflatable membrane at several (all?) node points.  That allows the structure as a whole to anchored (via pylons) into the regolith, and also allows for attachment points topside for some lightweight aluminum panels, upon which a few meters of regolith can be placed.  Thus the structure will not cave in if pressure is lost, or needs to be evacuated for some reason.

A second key to this is to have the geodesic structure itself be designed in such a way that it can be shipped in a 'collapsed' state, which 'unfolds' when the membrane is inflated.  That is, the entire structure (membrane and geodesic) will be constructed, integrated and tested Earthside before being collapsed into a small unit for shipment.  And on Mars surface simply inflating the membrane will cause the geodesic skeleton to gently unfold into place.

The way I envision this is to have each 'strut' of the structure actually be a hinged 'W' shape, and the W folds inward for shipment.  (Struts will have a rectangular cross section.)  The struts will also be hinged where they connect to the hubs.  The hinges of course must be quite robust, and there should be a positive locking mechanism at each hinge point when the structure unfolds.  This could theoretically be done with a strong magnet at each hinge point, which pulls the two members into exact alignment whereupon a latch engages.  Or there could be an additional, 'empty hinge' on the opposite side of each hinge, which the colonists then push into alignment and slide in a pin.

Anyway, once the structure is inflated and an airlock is attached, crew would descend into it and begin attaching 'floor joists' to the hard points (nodes), and then lay on floor panels.  Working their way up from bottom to top.  Model shown also has 6 structural poles attached to 6 lowest nodes, for support of floor joists.

I see a nominal design (shown) being about 10 meters tall and 13.33 meters in diameter.  With 3 layers:  'Basement' for storage, Mid layer for private quarters (probably dual occupancy), and top 'open space' for communal living.  Should be able to house ~20 colonists in relative comfort, akin to college dorm style living.

Top floor would be about 1 meter above local grade, which implies a 'divot' about 4 meters deep would have to be excavated.  Maybe somewhat less if a natural dip in the landscape is chosen.  Excavated material can be used later for regolith cover over the structure.

Above all I see the advantage of this to be a very rapid deployment of living space, which colonists could envision living in for decades.  What do you think?
 



I think the idea looks good, although you would need to "pumpkin" the top and bottom to increase curvature and reduce the strain on the fabric as per the Bigelow/Transhab designs. The geodesic struts could rather be assembled by hand once the module is inflated. You don't want something coming loose and getting stuck like happens with so many deployable structures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/17/2019 06:38 pm
Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.

Even without the top-weight, there's presumably an optimally squashed oblate spheroid (or oblate cylinder) that maximises usable floor-space, while minimising internal cross-linking and envelope mass.

The optimal degree of "squashedness" (ie eccentricity) is just related to the ratio between internal pressure and the pressure from the weight of regolith on top.

But yes, the Waffle Hab is my attempt to maximize usable floor space while minimizing envelope mass. It has the same mass efficiency as a horizontal cylinder, but in a far more practical shape.
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 10/17/2019 07:10 pm
Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.

Even without the top-weight, there's presumably an optimally squashed oblate spheroid (or oblate cylinder) that maximises usable floor-space, while minimising internal cross-linking and envelope mass.

[Also, if you are using ISRU materials (rather than Earth-shipped or... ships), there might be some benefit to having an unpressurised load-bearing shell around a pressurised module, where you have not just a few inches of Mars-ambient for insulation, but several feet for simply EVA maintenance and to run shared utilities between modules. (Running utilities internally through standard hatches is bulky and interferes with their value as emergency bulkheads.)]

TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Keep fighting the good fight, Sir.

O.K., so this talk of oblate spheroids and combining a load bearing structure with an inflatable gives me the push to finally expose an idea for a Mars habitat that I've had for several years.  Feedback welcome, but try to be gentle :-) 

The great advantage of an inflatable is obviously the great increase in usable volume between the deployed hab versus the shipped hab.  But the disadvantages are lack flat floors, and generally no 'structural integrity' to transmit floor, wall, equipment, etc. forces to terra firma (Mara firma?)  Likewise geodesic structures are great from a structural integrity standpoint, but require a large construction effort (compared to inflatables), which is magnified when it has to be done by folks in spacesuits. 

So why not combine the two ideas?  Have an inflatable oblate spheroid, which has an internal geodesic skeleton.  (See attached pic).  A key idea here is to have the geodesic 'hard points' (the nodes) poke through the inflatable membrane at several (all?) node points.  That allows the structure as a whole to anchored (via pylons) into the regolith, and also allows for attachment points topside for some lightweight aluminum panels, upon which a few meters of regolith can be placed.  Thus the structure will not cave in if pressure is lost, or needs to be evacuated for some reason.

A second key to this is to have the geodesic structure itself be designed in such a way that it can be shipped in a 'collapsed' state, which 'unfolds' when the membrane is inflated.  That is, the entire structure (membrane and geodesic) will be constructed, integrated and tested Earthside before being collapsed into a small unit for shipment.  And on Mars surface simply inflating the membrane will cause the geodesic skeleton to gently unfold into place.

The way I envision this is to have each 'strut' of the structure actually be a hinged 'W' shape, and the W folds inward for shipment.  (Struts will have a rectangular cross section.)  The struts will also be hinged where they connect to the hubs.  The hinges of course must be quite robust, and there should be a positive locking mechanism at each hinge point when the structure unfolds.  This could theoretically be done with a strong magnet at each hinge point, which pulls the two members into exact alignment whereupon a latch engages.  Or there could be an additional, 'empty hinge' on the opposite side of each hinge, which the colonists then push into alignment and slide in a pin.

Anyway, once the structure is inflated and an airlock is attached, crew would descend into it and begin attaching 'floor joists' to the hard points (nodes), and then lay on floor panels.  Working their way up from bottom to top.  Model shown also has 6 structural poles attached to 6 lowest nodes, for support of floor joists.

I see a nominal design (shown) being about 10 meters tall and 13.33 meters in diameter.  With 3 layers:  'Basement' for storage, Mid layer for private quarters (probably dual occupancy), and top 'open space' for communal living.  Should be able to house ~20 colonists in relative comfort, akin to college dorm style living.

Top floor would be about 1 meter above local grade, which implies a 'divot' about 4 meters deep would have to be excavated.  Maybe somewhat less if a natural dip in the landscape is chosen.  Excavated material can be used later for regolith cover over the structure.

Above all I see the advantage of this to be a very rapid deployment of living space, which colonists could envision living in for decades.  What do you think?
 



I think the idea looks good, although you would need to "pumpkin" the top and bottom to increase curvature and reduce the strain on the fabric as per the Bigelow/Transhab designs. The geodesic struts could rather be assembled by hand once the module is inflated. You don't want something coming loose and getting stuck like happens with so many deployable structures.

Thanks Lampyridae.  Could you expound a bit on the need for 'Pumpkin-ing' the top and bottom?  I know all pressure vessels are pushed to assume the shape of a sphere, but would there be that much differential strain pushing towards this if the membrane is pre-shaped into an oblate spheroid to begin with?  Or perhaps it could be pre-distorted to begin with, such that it gets pulled into a perfect oblate spheroid once fully pressurized?

I'd hate to move away from an integrated, preassembled geo structure on the inside, as building it on site would be a lot of work.  I think it's a bit different from other problematic deployable designs in that it is simply passively pulled into position by the expanding membrane.  (Though I'm sure that's the famous last words for any deployable.  "What could possibly go wrong, go wrong, go wrong..." )
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 10/17/2019 10:29 pm
Limiting thinking about habitat construction to regolith, ice and materials from Earth is too restrictive.

Has anyone thought about how we might be able to make cement (concrete) on Mars, based on minerals or rocks known to be available? Not the "Marscrete" mentioned up-thread, but something closer to Portland cement (plus sand and aggregate) or perhaps Roman concrete. It's one of the most widely used building materials on Earth, and seems like it would be immensely useful on Mars, too.
...
...
Yes, a number of research projects have addressed this question.

The principal problem is that the common concretes on Earth use water as a solute. When mixed with sand, rocks, and water, Portland cement undergo a chemical reaction (not just drying) to transform the mixture into concrete. This occurs over a number of hours or days. On Mars’ surface, water exposed to 0.5 psi ambient air immediately sublimates, which prevents the cement hardening process to proceed to completion.

I first looked into the problem in 2013 when I was writing articles for The Mars Pioneers website. I found that resins may offer a better approach, as some of them are less volatile with a longer hardening time.

What type of resins do you have in mind? What are the input materials?

What about non-hydraulic cement? Water is still needed, but only to make slaked lime. After that, it cures by reacting with CO2. Although CO2 density in the atmosphere is low, it will be collected for use in making rocket fuel (and probably for greenhouses), so it should be available to help cure cement, as well. If the starting material is CaCO3, CO2 is also released as part of the process of making CaO.

Hydraulic cement still seems possible to me. It would just require curing in a moderately pressurized environment. That might mean making concrete blocks "inside," and then moving them after they've cured. Floor tiles, walls and more could certainly be made that way. As long as the input materials are available, it couldn't be any more difficult than making steel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/17/2019 11:38 pm
...It's true that if the corrugated steel plates are cut to fit out the cargo hatch then Nissen huts would be a quite practical design, both for compactness during the trip to Mars and ease of assembly on the surface. The half-cylinder would also be an optimal shape for piling regolith on top.

Hehe... Perhaps this tried and true design will end up being multiplanetary.


Oh no, here we go again...  :o

The problem is, you'll have enormous pressure forces pushing up on the Quonset hut walls, because of the flat floor. You'd need huge heavy rock anchors to resist the pressure forces, and we've been down that road before. TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.


You've become increasingly snarky in the last couple of months. Perhaps frustration with those of a perceived lesser intellect?

Thank you, it is quite a heavy burden, being so handsome and intelligent.  Nooobody knows the trouble I've seen...   8)

Seriously though, I just want to avoid re-hashing a messy discussion taking up dozens of pages. See this thread for instance: https://forum.nasaspaceflight.com/index.php?topic=41526.0

The Nissen huts would of course, as mentioned above, have lots of regolith piled on top. That would be the 'rock anchor'.

The required thickness of regolith is far thicker than that required for radiation shielding. Now your Nissan hut has to be heavier to support the unpressurized weight, far heavier than just doubling it into a cylinder (and with a cylinder you ~double the pressurized volume too, whereas the reinforced Nissen hut would be the same size, just heavier).

The half-cylindrical shape would be optimal for - as I wrote - compactness during the trip and ease of assembly on the surface. Sure, an oblate spheroid is the theoretically best shape when actually deployed, but the other factors are very important as well. You have to look at the totality of transport, assembly and use. SpaceX has shown a huge propensity towards practical solutions instead of optimising for the last 3 percent. That's their whole ethos, you could say.

If you're going for compactness and ease of assembly on the surface, you can't beat inflatables. That's why I favor them so much.

Also, how would a rigid half-cylinder be more compact or easier to assemble than a whole cylinder? Clearly two half-cylinders can be bolted together, just like you'd bolt together the Nissen hut components.

And again, half-cylindrical shapes are not easy to assemble. You're either driving huge rock anchors, or piling 3-10x the required thickness of regolith on top of your hab (at 3-10x the excavation cost). And your hab design gets heavier to boot.

Nissen huts on the surface would be a quick and practical solution for rapid habs and work-shops

I think we've shown (in this post, and in many of pages of discussion) that that's not the case.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/18/2019 12:34 am
For an inflatable design your contingency load is carried by tensile wrapped Marscrete suspension towers, but I think in the long term you just make the pressure maintenance highly reliable (which is needed anyway) and delete the towers (just like Starship deleting LAS in favor of "just make it reliable").

I read "inflatable" and "towers" but I didn't notice "delete the towers." I'm inclined to think you need enough reliability right from the start, and you accept enough risk especially at the start, that you never need the towers, and you can have your nice big convenient habs starting with the very first landing.

I'm inclined to agree. Folks get touchy about it though, for some reason.

I think it's because being buried alive is a more relatable terror than vacuum asphyxia. It feels more "real" to us, from our perspective sitting here on Earth.

As I pointed out in my first post, you can have flat tensile floors in an inflatable. You'll need a cover layer to protect it from wear, but you don't need a separate structural floor. Image is attached.

Nice! I've been picturing a single story, something like an air mattress, and I hadn't thought of the tensile-floor trick.

Of course if you're hanging lots of floors and their load from the roof, like in your design, you don't get to pile on as much regolith. I'm reasonably comfortable with the radiation (and thermal) shielding you get from 5 PSI / 33 kPA of regolith, but I wouldn't necessarily want to cut that in half.

9 tonnes per m^2? That's on the high end, but not crazy.

No need to cut the shield mass in half either. One atmosphere of pressure with 5 PSI of regolith on top would support 180 lb/ft^2 on all four floors before the net upward force (ie the upward push beyond the weight of the regolith) were even reduced by half.

But you bring up a good point, and this is one of the constraints that limits the maximum number of levels.

You'll need insulation anyway, since regolith doesn't actually make a great insulating layer (thermal mass yes, insulation no). But if you put the thermal insulation outside the regolith instead, it will equalize to the interior temperature.

A little Google searching says that packed terrestrial dirt has an R value of 0.125-0.25 per inch and brick is 0.8 per 4 inches. So 2 meters of loose dry regolith should have an I-P R value of 10-20 or better. Let's be pessimistic and say 100 K temperature difference and R value of 10 (~1.7 SI). Then you only lose ~60 W per square meter, unless I'm making a really silly math error. If each person needs 10 kW of power, they need about 170 square meters to conduct the waste heat away. Fully inflatable habs are cheap, but I doubt people will have that much space apiece.

This assumes heat loss from the walls is the only heat removal source. While at first this seems efficient (hey, no radiators!), it is problematic for two reasons:

• Efficiency. Why use the heat once when you can use it twice? Waste heat can be used to melt or sublimate ice, recycle water via distillation, or heat externally-lit greenhouses (if used).

• Reliability. In a low-power situation you can live off of stored reserves of oxygen, water, food, etc. But storing energy is expensive. You can burn your in-situ methalox for energy and heat, but the higher your insulation the longer that will stretch (or the less it will cost per day).

I'm a fan of switchable vacuum insulation blankets myself. Pump out the air and they become superinsulating, but the insulatiion can be switched "off" for cooling or solar heat gain.

Light tubes are nice. You can delete the entire "tube" part and it still works too. Just position mirrors outside your hab and bounce sunlight in horizontally beneath an overhang.

Overhang has to support regolith. That's actual construction work. It'll come down to whatever is easier to ship, assemble, and place.

Yes. I almost wrote "radiation shielding overhang," but it seemed obvious. Heavier construct overall, but with a large area it's probably lighter on a per-photon basis (especially as the light tube "zig zag" gets impractical at large diameters).

I think both are nice options.

* Airlocks (OK, you actually need airlocks)
* Expansion kits that can attach more volume to your hab without deflating it (yes, this is straightforward if you design for it)

Presumably these would use a common hatch design.

I was picturing something bigger than a hatch - attach an inflated tube to the outside of a wall, then cut away the wall.

Ahh, ok. I had a concept for that with the Waffle Hab too. Each wall/floor seam is joined with a "buckle" that allows individual components to be replaced (eg due to wear). But this would also allow simple expansion. Just attach the new tensile floors to the existing "outer hoops," seal the outside, pressurize the new section, and remove the old outer hoop sections (which are now inside the new section).

Film ducts seem reasonable for climate control, since they can be pre-installed then packed flat inside the inflatable.

Machinery for heating, cooling, dehumidifying, gas chemistry control... Also, some ducts need to suck (though I suppose you could run wires to power fans at each inlet).

Good idea about the fans. I figured just use the entire space as the "return air duct," but your idea is better.

One possibility is using distributed ductless mini-split units. Tiny refrigerant lines carrying pressurized CO2 would certainly take up less of your (precious) pressurized volume than forced air ducts, and less power too. But you still need some airflow to allow for CO2/O2 refreshing and removal of contaminants like dust, VOCs, etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 10/18/2019 12:39 am
...
...
What type of resins do you have in mind? What are the input materials?

What about non-hydraulic cement? Water is still needed, but only to make slaked lime. After that, it cures by reacting with CO2. Although CO2 density in the atmosphere is low, it will be collected for use in making rocket fuel (and probably for greenhouses), so it should be available to help cure cement, as well. If the starting material is CaCO3, CO2 is also released as part of the process of making CaO.

Hydraulic cement still seems possible to me, as well. It would just require curing in a moderately pressurized environment. That might mean making concrete blocks "inside," and then moving them after they've cured. Floor tiles, walls and more could certainly be made that way. As long as the input materials are available, it couldn't be any more difficult than making steel.
I don’t have any current information. When I was checking out alternatives to cement I contacted companies that produce off-the-shelf resin products, especially the Research Dept. Tip: If you investigate this, check the time and temperatures of curing to be compatible with Mars conditions. May have to supply heat during curing.

Added: I was investigating resin as a substitute for mortar, not construction cement. The proposed construction method employed stone blocks cut directly from native stone massifs. Pioneers would use diamond-tipped chain saws as employed by stone industries on Earth - it was a low-energy approach using simple equipment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/18/2019 12:50 am
Nitpick: if you're piling regolith on top, the optimal shaped pressure vessel is an oblate spheroid ("squashed" in the direction of gravity), not a hemisphere or half-cylinder.

Even without the top-weight, there's presumably an optimally squashed oblate spheroid (or oblate cylinder) that maximises usable floor-space, while minimising internal cross-linking and envelope mass.

[Also, if you are using ISRU materials (rather than Earth-shipped or... ships), there might be some benefit to having an unpressurised load-bearing shell around a pressurised module, where you have not just a few inches of Mars-ambient for insulation, but several feet for simply EVA maintenance and to run shared utilities between modules. (Running utilities internally through standard hatches is bulky and interferes with their value as emergency bulkheads.)]

TL;DR the heavy-duty rock anchors needed are far heavier than just doubling the half-cylinder pressure vessel into a whole cylinder.

Keep fighting the good fight, Sir.

O.K., so this talk of oblate spheroids and combining a load bearing structure with an inflatable gives me the push to finally expose an idea for a Mars habitat that I've had for several years.  Feedback welcome, but try to be gentle :-) 

[snip]

Above all I see the advantage of this to be a very rapid deployment of living space, which colonists could envision living in for decades.  What do you think?
 

I like it a lot. The self-erection via inflation is especially clever. I tried to come up with a workable scheme, but it seems you nailed it. :)

It reminds me a bit of this NASA study for a moon base: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900015683.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/18/2019 02:20 am
The Nissen huts would of course, as mentioned above, have lots of regolith piled on top. That would be the 'rock anchor'.
At 10 tonnes-force of air pressure per square metre, you need about 15m of regolith to balance the air pressure. You'll need to shape this so that the load is also against the sloping walls with the correct sideways force, otherwise the structure will still deform.
...And in case of a leak and loss of air pressure the hab would obviously be crushed under the weight of that mountain of regolith...

So you create an unnecessary problem (using the wrong shape for a pressure vessel). Solve it with an unnecessary solution (using excessive regolith to force the wrong shape). Then use that to condemn the whole idea of regolith shielding (because of your completely artificial problem).

If you don't use the wrong shape, and you don't use excess regolith as hold-down mass, then you end up with perhaps a tonne-force/m² for shielding, requiring just 1/10th of 1atm to support. Less, since some of the side-weight is supporting itself. Any catastrophic failure that dropped the pressure suddenly to less than 0.1atm has already killed everyone inside (even if they were on supplemental oxygen, since you're getting damn close to the Armstrong limit before the roof starts to fall.)

Additionally, if you want failsafe, you don't need to have a single continuous volume. You can divide the hab into semi-independent pressure-volumes, such that if one section fails, the other(s) can individually keep the structure expanded, including the regolith weight. That shouldn't be difficult to design. And it shouldn't cost you much internal volume, if, under non-emergency conditions, you can move freely between the sections.



In reality, a "leak" in an inflatable structure will not be that fast. Even a significant failure will give you tens of minutes (up to hours) to evacuate to another hab. And give you longer still to effect repairs.

Otoh...

- Yup, more than ever I'm convinced that tunnels are the way to go...

Have you considered the typical failure modes for tunnels? Or are we using a double standard?

[but Musk said!]

Is that also where he described "ITS" as 12m wide and made of carbon composites.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ChrisPhoenix on 10/19/2019 09:11 am
No need to cut the shield mass in half either. One atmosphere of pressure with 5 PSI of regolith on top would support 180 lb/ft^2 on all four floors before the net upward force (ie the upward push beyond the weight of the regolith) were even reduced by half.

You're figuring 1 atm internal pressure? I've been assuming it would be 3 PSI O2 and 2 PSI nitrogen/argon. High pressure is problematic for space suit mobility, and you want to live at the same pressure you use for your suits. Also, higher pressure = higher mass to contain it. (Argon because there's a fair amount of it in the Martian atmosphere, and because (I think) it would reduce the severity of fire.)

This assumes heat loss from the walls is the only heat removal source. While at first this seems efficient (hey, no radiators!), it is problematic for two reasons:

• Efficiency. Why use the heat once when you can use it twice? Waste heat can be used to melt or sublimate ice, recycle water via distillation, or heat externally-lit greenhouses (if used).

• Reliability. In a low-power situation you can live off of stored reserves of oxygen, water, food, etc. But storing energy is expensive. You can burn your in-situ methalox for energy and heat, but the higher your insulation the longer that will stretch (or the less it will cost per day).

True that you can use the heat to distill water etc. But that requires transporting the heat. I suspect sun-concentrating mirrors will provide an easier and lower cost heat source for most applications. You won't be limited to room temperature, which makes lots of engineering easier.

I'm not assuming there would be lots of spare power even in a non-low-power situation. Every bit of power used has to come from something massive and hard to maintain. So it's not at all obvious to me that the power requirement could be cut by a greater fraction than the living space requirement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/19/2019 09:38 am
2PSI oxygen out of 5 will result in unconsciousness and possibly death.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/19/2019 10:11 am
You're figuring 1 atm internal pressure? I've been assuming it would be 3 PSI O2 and 2 PSI nitrogen/argon.

60% oxygen at 5PSI is a huge fire risk. Teflon would burn. Silicone would burn like a road flare.

[Edit: And that's not counting the greater speed of burn due to lower gravity.]

(Argon because [...] (I think) it would reduce the severity of fire.)

That would make it worse. Fire burns faster/hotter in Argon/Oxy mix than in the same ratio of N₂/O₂. It's not a huge difference, considering the horror show you're creating at 60% O₂.

(Argon is used as a building fire suppressor because it's heavier than air and tends to displace the oxygen rich air and smothers fires near the floor. In an air mix, it sucks.)

I suspect sun-concentrating mirrors will provide an easier and lower cost heat source for most applications.

Sun concentrators are very unreliable on Mars due to the dust in the air. Even on relatively clear days, it can be a significant defocuser.
Title: Re: Envisioning Amazing Martian Habitats
Post by: GORDAP on 10/19/2019 03:11 pm
You're figuring 1 atm internal pressure? I've been assuming it would be 3 PSI O2 and 2 PSI nitrogen/argon.

60% oxygen at 5PSI is a huge fire risk. Teflon would burn. Silicone would burn like a road flare.

[Edit: And that's not counting the greater speed of burn due to lower gravity.]

(Argon because [...] (I think) it would reduce the severity of fire.)

That would make it worse. Fire burns faster/hotter in Argon/Oxy mix than in the same ratio of N₂/O₂. It's not a huge difference, considering the horror show you're creating at 60% O₂.

(Argon is used as a building fire suppressor because it's heavier than air and tends to displace the oxygen rich air and smothers fires near the floor. In an air mix, it sucks.)

I suspect sun-concentrating mirrors will provide an easier and lower cost heat source for most applications.

Sun concentrators are very unreliable on Mars due to the dust in the air. Even on relatively clear days, it can be a significant defocuser.

Paul, aren't flames less aggressive in lower gravity (everything else being equal)?  I'd have thought that convection brings new oxygen to the flame source, and convection would be less prominent as gravity decreases.  But I'm not expert.  Is there an effect I'm not thinking of?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/19/2019 04:08 pm
Coober Pedy in a short BBC clip: https://www.bbc.com/reel/video/p07qsdg9/life-against-the-odds-in-australia-s-underground-town

Underground and solar-powered, reminds me of our Martian future. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Genial Precis on 10/19/2019 04:57 pm
...
...
What type of resins do you have in mind? What are the input materials?

What about non-hydraulic cement? Water is still needed, but only to make slaked lime. After that, it cures by reacting with CO2. Although CO2 density in the atmosphere is low, it will be collected for use in making rocket fuel (and probably for greenhouses), so it should be available to help cure cement, as well. If the starting material is CaCO3, CO2 is also released as part of the process of making CaO.

Hydraulic cement still seems possible to me, as well. It would just require curing in a moderately pressurized environment. That might mean making concrete blocks "inside," and then moving them after they've cured. Floor tiles, walls and more could certainly be made that way. As long as the input materials are available, it couldn't be any more difficult than making steel.
I don’t have any current information. When I was checking out alternatives to cement I contacted companies that produce off-the-shelf resin products, especially the Research Dept. Tip: If you investigate this, check the time and temperatures of curing to be compatible with Mars conditions. May have to supply heat during curing.

Added: I was investigating resin as a substitute for mortar, not construction cement. The proposed construction method employed stone blocks cut directly from native stone massifs. Pioneers would use diamond-tipped chain saws as employed by stone industries on Earth - it was a low-energy approach using simple equipment.
If you need a binder for regolith aggregate, maybe water would be suitable. This study (https://www.cambridge.org/core/services/aop-cambridge-core/content/view/782288843596EF3FBA8BAD4E019B75D0/S0022143000011308a.pdf/triaxial_testing_of_frozen_sand.pdf) achieved yield strength of 14 MPa for frozen sand with 14 wt% water content. Which is certainly a bit low by the standards of concrete, but seems like a good "lightweight" solution in that you need to be producing significant quantities of water anyway, so a "mostly-regolith with water binder" construction material is something you can do with less equipment. You need to keep it away from hot things, or else insulate it.

And I suppose the surface needs a vapor barrier to stop it evaporating. And I guess you want to be near the equator for solar power, and the temperatures can sometimes rise above freezing there, implying that you'd want to cover it with a reflective layer and/or insulation. That takes away some of the advantages.

You know what, it would be really useful to have something like rockwool on Mars, at a low energy cost. The final material is all oxides, just hairy, so with clever apparatus maybe you could build something that produced rockwool in large quantities at low embodied energy. Plentiful insulation is useful.

It's tempting (to me at least) to suggest rockwool-water composites, but ISTM that the vapor pressure of water is so high even at -40 C that you'd want either an impermeable layer or a low wt% of water so that there are tortuous paths to slow evaporation. In fact, concrete does not seem so unreasonable on Mars. You'd spray it with something like the curing compounds used on earth, which help concrete cure by forming an impermeable layer to retain water.

In my mind the issue with concrete is embodied energy. Any energy you don't use on concrete you can use on something else, and CaCO3 to CaO + CO2 requires at least 3 kJ/g.

Maybe that's wrongheaded. Maybe what really happens is that you ship over a bunch of Gen IV nuclear power plants, of one sort or another, and energy ends up being plentiful enough that you optimize for other things.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/19/2019 05:05 pm
No need to cut the shield mass in half either. One atmosphere of pressure with 5 PSI of regolith on top would support 180 lb/ft^2 on all four floors before the net upward force (ie the upward push beyond the weight of the regolith) were even reduced by half.

You're figuring 1 atm internal pressure?

Yes, for this particular assumption I wanted to choose a conservative number, hence 1 atm. You could surely lower the pressure to reduce mass, eg running at 10.9 PSI = 8000 ft (like pressurized airplanes do). Even then, there's still plenty of upward force to hold up the regolith shield and the weight held up on each level.

This assumes heat loss from the walls is the only heat removal source. While at first this seems efficient (hey, no radiators!), it is problematic for two reasons:

• Efficiency. Why use the heat once when you can use it twice? Waste heat can be used to melt or sublimate ice, recycle water via distillation, or heat externally-lit greenhouses (if used).

• Reliability. In a low-power situation you can live off of stored reserves of oxygen, water, food, etc. But storing energy is expensive. You can burn your in-situ methalox for energy and heat, but the higher your insulation the longer that will stretch (or the less it will cost per day).

True that you can use the heat to distill water etc. But that requires transporting the heat.

On Mars carrying heat is easy. Just tiny pipes and supercritical CO2. It's abundant on Mars, and it's more efficient than most refrigerants used terrestrially.

I suspect sun-concentrating mirrors will provide an easier and lower cost heat source for most applications.

I'm actually a bigger fan of non-concentrating solar. In any (high magnification) concentrating solar system the Sun-tracking system is large mass driver, a possible point of failure, and a dependency on resupply from Earth.

You won't be limited to room temperature, which makes lots of engineering easier.

Correction: waste hab heat isn't limited to room temperature. It's limited to the operating temperature of the equipment that you're cooling. :)

I'm not assuming there would be lots of spare power even in a non-low-power situation. Every bit of power used has to come from something massive and hard to maintain. So it's not at all obvious to me that the power requirement could be cut by a greater fraction than the living space requirement.

Exactly. By making a hab design that you must heat with lots of power all the time (because it's poorly insulated), you have no options to cut power requirements in a contingency. Instead you must make the power source bigger, which makes it even more (in your own words) "massive and hard to maintain."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ace on 10/20/2019 12:28 am
You know what, it would be really useful to have something like rockwool on Mars, at a low energy cost. The final material is all oxides, just hairy, so with clever apparatus maybe you could build something that produced rockwool in large quantities at low embodied energy. Plentiful insulation is useful.

It's tempting (to me at least) to suggest rockwool-water composites, but ISTM that the vapor pressure of water is so high even at -40 C that you'd want either an impermeable layer or a low wt% of water so that there are tortuous paths to slow evaporation. In fact, concrete does not seem so unreasonable on Mars. You'd spray it with something like the curing compounds used on earth, which help concrete cure by forming an impermeable layer to retain water.

In my mind the issue with concrete is embodied energy. Any energy you don't use on concrete you can use on something else, and CaCO3 to CaO + CO2 requires at least 3 kJ/g.

Maybe that's wrongheaded. Maybe what really happens is that you ship over a bunch of Gen IV nuclear power plants, of one sort or another, and energy ends up being plentiful enough that you optimize for other things.

I like the idea of making and using rockwool as insulation. A version of it can be made from Basalt, which is plentiful on Mars.

I'm less enthusiastic about using water ice as a building material. I would be concerned about long-term stability and having to be constantly cautious of exposure to even very mild heat from any source.

For industrial processes on Mars that require heat, nuclear is certainly an option, although my guess is that it's more of a long-term one, at least based on the way things look today. Near-term, I think a solar furnace would be more efficient than solar electric. Even for basic water heating, direct solar heat will almost certainly be a better choice. Vacuum tube-style solar heat collectors are surprisingly efficient.

Also, concrete hydration is exothermic. The heat given off in the process should be recoverable to some degree.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/20/2019 02:15 am
[fire in low gravity]
Paul, aren't flames less aggressive in lower gravity (everything else being equal)?  I'd have thought that convection brings new oxygen to the flame source, and convection would be less prominent as gravity decreases.  But I'm not expert.  Is there an effect I'm not thinking of?

There are two effects related to convention, the rate that it brings in fresh oxygen, and the rate that it take away heat. They are working in the opposite direction, one lets the fire burn hotter, the other cools it. But as you lower the rate of convection (under lower gravity), the two effects don't scale uniformly. For certain values, the extra heating from less convection dominates. Below a critical threshold, the self-smothering from lack of oxygen will dominate.

It turns out that, at least in testing, lunar gravity is the threshold, producing the greatest flammability in materials. Mars gravity is also worse than 1g, but not as bad as lunar gravity. Below lunar-g, flammability reduces as self-smothering dominates.

Graph for Mylar below. In the tests, flammability was measured by the minimum amount of oxygen required to sustain fire. Anything above that, the material can burn, anything below and it will self-extinguish. A lower number correlates to higher flammability.

Graph comes from NASA Glenn drop test (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130010991.pdf) research.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ChrisPhoenix on 10/20/2019 06:59 am
2PSI oxygen out of 5 will result in unconsciousness and possibly death.

No. 3PSI O2 (which is what I wrote) is the partial pressure of oxygen at sea level on Earth. Lungs work on partial pressure, so you'd get as much oxygen in that atmosphere as you'd get back home.

2 PSI is not even incapacitating. The atmospheric pressure (and thus O2 partial pressure) drop by 1/3 at around 2500 meters elevation. The FAA lets un-acclimatized people pilot aircraft without supplemental oxygen up to 12,500 feet (3810 meters).
Title: Re: Envisioning Amazing Martian Habitats
Post by: ChrisPhoenix on 10/20/2019 07:22 am
You're figuring 1 atm internal pressure? I've been assuming it would be 3 PSI O2 and 2 PSI nitrogen/argon.

60% oxygen at 5PSI is a huge fire risk. Teflon would burn. Silicone would burn like a road flare.

After the Apollo 1 fire, NASA decided that the Apollo capsules should use 60% O2, 40% N2 at 16 PSI on the ground, and 100% O2 at 5 PSI in space. https://www.encyclopedia.com/science/news-wires-white-papers-and-books/oxygen-atmosphere-spacecraft (https://www.encyclopedia.com/science/news-wires-white-papers-and-books/oxygen-atmosphere-spacecraft)

Here's another data point: Dille, et. al., published by the FAA, November, 1963: “The Flammability of Lip, Face and Hair Preparations in the Presence of 100% Oxygen.” According to https://www.planeandpilotmag.com/article/flying-high-unpressurized/#.XawHJ-jYq00 (https://www.planeandpilotmag.com/article/flying-high-unpressurized/#.XawHJ-jYq00),
Quote
The authors studied many products in the presence of “high concentrations and pressures of oxygen and of static sparks.” They concluded, “A wide margin of safety was found for their use at or below one atmosphere of pressure,” but not so at hyperbaric pressure as low as two atmospheres.

So I think you're exaggerating the risk and behavior of fire in moderately enriched environments, especially at relatively low pressure.

(Argon because [...] (I think) it would reduce the severity of fire.)

That would make it worse. Fire burns faster/hotter in Argon/Oxy mix than in the same ratio of N₂/O₂. It's not a huge difference, considering the horror show you're creating at 60% O₂.

I had assumed that argon gas had a higher specific heat than nitrogen, but it turns out to be slightly lower. So that could make it worse - but probably not much worse.

Argon has lower thermal conductivity than air - that's why divers like to use it in dry suits. That might concentrate the heat in a smaller area, but that effect would probably be small.

At any rate, there's plenty of nitrogen in the Martian atmosphere, so it's easy to make an oxygen/nitrogen atmosphere without importing anything.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/20/2019 08:05 am
In a closed habitat fire is a very big risk, even if as unlikely as on Earth. In a base with staff that can be expected to be careful some risk can be accepted. In a settlement with many people of all ages the safety level should be higher IMO.

I have seen an impressive video a while ago where they showed that at sea level pressure with slightly reduced oxygen open fire becomes nearly impossible. The oxygen level is still comfortable for humans. A lighter or match won't light. A candle or torch brought in would extinguish. I think we should have that level of safety for a settlement.

I see no need to have a pressure level in the main habitat that allows easy space suit operations. Most people will rarely need to go outside. Going to a pressure level half as high can be done  without prebreathing. A simple and efficient setup would be having the habitat at 1atm/15psi. Have a temporary habitat with half that, 7.5-8 psi where you can stay over night in preparation of outside work and  stay for several days for continuous outside work. No prebreathing necessary over that period and also visits by people from the main habitat without prebreathing are easily possible.

Tunneled living space has no problem with sea level pressure. Domes with plants and outside view can have lower pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/20/2019 08:32 am
You're figuring 1 atm internal pressure? I've been assuming it would be 3 PSI O2 and 2 PSI nitrogen/argon.
60% oxygen at 5PSI is a huge fire risk. Teflon would burn. Silicone would burn like a road flare.
After the Apollo 1 fire, NASA decided that the Apollo capsules should use 60% O2, 40% N2 at 16 PSI on the ground, and 100% O2 at 5 PSI in space.

After doing extensive reviews on the materials used in the capsule and LM, and a making a huge effort to reduce ignition sources. (Just as they have on every vehicle since.)

The materials they'd initially used were safe in 21% Oxygen at atmospheric pressure, but were a fire hazard at 100% oxygen even at operating pressure (5psi). They had to change those materials (and alter the electrical systems) to make it safe.

(Aside: PTFE (Teflon) really does become flammable at 60% oxygen at 5psi. While Silicone (just barely flammable @21%/15psi) becomes highly flammable @60%/5psi, being able to consume more than half the oxygen in the air before it self-extinguishes.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/20/2019 08:46 am
I have seen an impressive video a while ago where they showed that at sea level pressure with slightly reduced oxygen open fire becomes nearly impossible. The oxygen level is still comfortable for humans. A lighter or match won't light. A candle or torch brought in would extinguish. I think we should have that level of safety for a settlement.

Agreed. A slightly higher pressure at slightly lower oxygen levels would solve most issues.

I see no need to have a pressure level in the main habitat that allows easy space suit operations. Most people will rarely need to go outside. Going to a pressure level half as high can be done  without prebreathing. A simple and efficient setup would be having the habitat at 1atm/15psi. Have a temporary habitat with half that, 7.5-8 psi where you can stay over night in preparation of outside work and  stay for several days for continuous outside work. No prebreathing necessary over that period and also visits by people from the main habitat without prebreathing are easily possible.

AIUI, the newer suits they are developing have higher operating pressure to reduce or eliminate the need for pre-breathing. The xEMU runs at just over 8psi, the old EMU suits were around 4.5psi.

However, IMO, it doesn't make sense to have different parts of a settlement at different operating pressures. Moving between even a few PSI difference would require an airlock and time consuming pumping.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/20/2019 10:07 am
2PSI oxygen out of 5 will result in unconsciousness and possibly death.

No. 3PSI O2 (which is what I wrote) is the partial pressure of oxygen at sea level on Earth. Lungs work on partial pressure, so you'd get as much oxygen in that atmosphere as you'd get back home.

2 PSI is not even incapacitating. The atmospheric pressure (and thus O2 partial pressure) drop by 1/3 at around 2500 meters elevation. The FAA lets un-acclimatized people pilot aircraft without supplemental oxygen up to 12,500 feet (3810 meters).


No, 2PSI (14kPa) is not tolerable: see below. That is why I wrote that number. "Equivalent to x altitude and we're fine" doesn't cut it for spaceflight atmospheres. At 1/3 bar, you are balancing right on the knife edge. Lose just a little pressure or lose too much oxygen and suddenly you've gone from barely-tolerable 3PSI to unconsciousness at 2PSI. This happens faster than if you lose pressure (same size hole) with a sea-level environment. This (along with fire) is why modern spacecraft operate at 1 bar and don't instead try to shave off mass with a lower cabin pressure. Aircraft can quickly descend to safe altitude. Spacecraft cannot. Apollo-era missions operated in a somewhat hypoxic environment partly because of this needed margin of safety.

3.5 PSI is the normal lower limit for spacesuit air pressures. The available O2 pressure must be subtracted from alveolar air pressure (12kPa or so) to get O2 partial pressure (which is what is medically relevant).

As for Argon, it seems it is just plain bad. It's worse than nitrogen for decompression illness.

Source: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000053485.pdf
Source (human subjects, spaceflight application): https://www.ncbi.nlm.nih.gov/pubmed/14692466

And back in 2017, Paul451 pointed out (https://forum.nasaspaceflight.com/index.php?topic=42174.msg1636663#msg1636663) that argon's lower thermal capacity made it even worse as a buffer gas, and presumably, a convective cooling gas. But it's great for insulating spaces between walls, ice windows etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/20/2019 03:35 pm
AIUI, the newer suits they are developing have higher operating pressure to reduce or eliminate the need for pre-breathing. The xEMU runs at just over 8psi, the old EMU suits were around 4.5psi.

However, IMO, it doesn't make sense to have different parts of a settlement at different operating pressures. Moving between even a few PSI difference would require an airlock and time consuming pumping.

I am not sure this is what SpaceX would do for their surface suit. It looks complex and expensive. They want a suit that can be mass produced at low cost and is comfortable to wear which will be low pressure, maybe 4 PSI.

I also see no problem in that extra habitat. I see a very large habitable volume for many people. In relation this transfer habitat is very small even if bigger than a whole habitat as envisioned by NASA. It enables an easy workflow.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/20/2019 05:34 pm
I'm currently trying to digest some research on hybobaria and hyperoxia on VIIP (that nasty thing that makes astronauts lose their eyesight) and it seems that it may aggravate it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: josephcouvillion on 10/20/2019 07:10 pm
However, IMO, it doesn't make sense to have different parts of a settlement at different operating pressures. Moving between even a few PSI difference would require an airlock and time consuming pumping.

I think that this statement is too absolute, it depends on the size and nature of the settlement.

I could see a large settlement with families having a 1atm zone, with lots of radiation protection, maybe artificial gravity if that turns out to be a benefit. And an outer zone that would operate at whatever pressure makes EVA easy. And it is possible that in such a settlement an intermediate zone might work so that people from both side could easily meet at, might be worthwhile.

Of course a small base  wouldn't be workable in that manner, there would be too much need to cross airlocks.

 These different zone would have different designs and construction based on their requirements.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 10/21/2019 06:16 pm
However, IMO, it doesn't make sense to have different parts of a settlement at different operating pressures. Moving between even a few PSI difference would require an airlock and time consuming pumping.

I think that this statement is too absolute, it depends on the size and nature of the settlement.

I could see a large settlement with families having a 1atm zone, with lots of radiation protection, maybe artificial gravity if that turns out to be a benefit. And an outer zone that would operate at whatever pressure makes EVA easy. And it is possible that in such a settlement an intermediate zone might work so that people from both side could easily meet at, might be worthwhile.

Of course a small base  wouldn't be workable in that manner, there would be too much need to cross airlocks.

 These different zone would have different designs and construction based on their requirements.

I think there's a trade-off between convenience and structural weight benefits which is a difficult one to call. It depends on which habitat in what time frame. But I'm not at all sure about having artificial gravity! :o
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/21/2019 06:49 pm
However, IMO, it doesn't make sense to have different parts of a settlement at different operating pressures. Moving between even a few PSI difference would require an airlock and time consuming pumping.

I think that this statement is too absolute, it depends on the size and nature of the settlement.

I could see a large settlement with families having a 1atm zone, with lots of radiation protection, maybe artificial gravity if that turns out to be a benefit. And an outer zone that would operate at whatever pressure makes EVA easy. And it is possible that in such a settlement an intermediate zone might work so that people from both side could easily meet at, might be worthwhile.

Of course a small base  wouldn't be workable in that manner, there would be too much need to cross airlocks.

 These different zone would have different designs and construction based on their requirements.
You mean large rotating habitats, I expect, to provide the artificial gravity?  Wonder what the energy requirement might be to have them turning, and if this energy might mostly become heat and be used to heat the colony?
Title: Re: Envisioning Amazing Martian Habitats
Post by: josephcouvillion on 10/21/2019 08:46 pm
You mean large rotating habitats, I expect, to provide the artificial gravity?  Wonder what the energy requirement might be to have them turning, and if this energy might mostly become heat and be used to heat the colony?

Well some sort of tilted rotated platform is the only way I know to generate additional gravity.

The exact size is dependent on the requirements, which we don't know yet. Low G need occasionally could be small rooms.
But we don't know what fetus or children need to develop in a normal manner, or even what adults need in the long term.

To the degree that we have a settlement raising children I expect there will be some effort to protect pregant women and children from possible health effects of low G and radiation, while men tend to do EVA wearing flannels and carrying double headed axes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: ChrisPhoenix on 10/22/2019 05:52 am
2PSI oxygen out of 5 will result in unconsciousness and possibly death.

No. 3PSI O2 (which is what I wrote) is the partial pressure of oxygen at sea level on Earth. Lungs work on partial pressure, so you'd get as much oxygen in that atmosphere as you'd get back home.

2 PSI is not even incapacitating. The atmospheric pressure (and thus O2 partial pressure) drop by 1/3 at around 2500 meters elevation. The FAA lets un-acclimatized people pilot aircraft without supplemental oxygen up to 12,500 feet (3810 meters).


No, 2PSI (14kPa) is not tolerable: see below. That is why I wrote that number. "Equivalent to x altitude and we're fine" doesn't cut it for spaceflight atmospheres. At 1/3 bar, you are balancing right on the knife edge. Lose just a little pressure or lose too much oxygen and suddenly you've gone from barely-tolerable 3PSI to unconsciousness at 2PSI.


OK, I agree with you that that chart says 2 O2 / 5 total PSI is not tolerable even though 2 O2 / 15 total PSI is tolerable (but hypoxic). It does say 3/5 PSI is unimpaired.

I can believe there's some effect which says it's not absolute partial pressure, but pressure relative to some non-zero number, that's important. I don't think it's called "alveolar pressure" though. https://en.wikipedia.org/wiki/Alveolar_pressure (https://en.wikipedia.org/wiki/Alveolar_pressure)

So let's drop argon completely. And I'll agree that R&D needs to be done to balance risks vs. costs in low-pressure low-gravity environments, because fire is a significant concern as N2 decreases. Decompression may or may not be (given that the same mass has higher safety factor at lower pressure). Note that in a dirt-covered hab, micrometeor strikes are not a concern (as they are in spacecraft), so there's a significant cause of small/survivable holes that doesn't have to be considered.

(Side note re the alveolar thing: I'm really tired of dumbed-down science-for-kids that glosses over small effects. If heavy and light objects really fell at exactly the same speed in a vacuum, then things would fall at the same speed on the Moon as on Earth. Which I actually believed for a while, with impeccable logic, reasoning from that inaccurate "fact." Imagine dropping the Moon on the Earth, and then shift your frame of reference so you're dropping the Earth on the Moon...)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/22/2019 06:42 am
Regarding micrometeorites: https://iopscience.iop.org/article/10.1086/128793/pdf

"...meteorites of ~ 10 grams and less are completely decelerated by the Martian atmosphere and impact the Martian surface at terminal free-fall velocities."

The paper also has some useful charts relating meteorite mass to impact velocity and crater size, which could help quantify the meteorite risk.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/22/2019 01:04 pm
2PSI oxygen out of 5 will result in unconsciousness and possibly death.

No. 3PSI O2 (which is what I wrote) is the partial pressure of oxygen at sea level on Earth. Lungs work on partial pressure, so you'd get as much oxygen in that atmosphere as you'd get back home.

2 PSI is not even incapacitating. The atmospheric pressure (and thus O2 partial pressure) drop by 1/3 at around 2500 meters elevation. The FAA lets un-acclimatized people pilot aircraft without supplemental oxygen up to 12,500 feet (3810 meters).


No, 2PSI (14kPa) is not tolerable: see below. That is why I wrote that number. "Equivalent to x altitude and we're fine" doesn't cut it for spaceflight atmospheres. At 1/3 bar, you are balancing right on the knife edge. Lose just a little pressure or lose too much oxygen and suddenly you've gone from barely-tolerable 3PSI to unconsciousness at 2PSI.


OK, I agree with you that that chart says 2 O2 / 5 total PSI is not tolerable even though 2 O2 / 15 total PSI is tolerable (but hypoxic). It does say 3/5 PSI is unimpaired.

I can believe there's some effect which says it's not absolute partial pressure, but pressure relative to some non-zero number, that's important. I don't think it's called "alveolar pressure" though. https://en.wikipedia.org/wiki/Alveolar_pressure (https://en.wikipedia.org/wiki/Alveolar_pressure)

So let's drop argon completely. And I'll agree that R&D needs to be done to balance risks vs. costs in low-pressure low-gravity environments, because fire is a significant concern as N2 decreases. Decompression may or may not be (given that the same mass has higher safety factor at lower pressure). Note that in a dirt-covered hab, micrometeor strikes are not a concern (as they are in spacecraft), so there's a significant cause of small/survivable holes that doesn't have to be considered.

(Side note re the alveolar thing: I'm really tired of dumbed-down science-for-kids that glosses over small effects. If heavy and light objects really fell at exactly the same speed in a vacuum, then things would fall at the same speed on the Moon as on Earth. Which I actually believed for a while, with impeccable logic, reasoning from that inaccurate "fact." Imagine dropping the Moon on the Earth, and then shift your frame of reference so you're dropping the Earth on the Moon...)


I'm being sloppy. The correct term is alveolar partial oxygen pressure, which is made up of water vapour pressure and CO2 pressure, which comes to about 2psi or 12kPa in total, which is why the limit sits at around 3.6psi/20kPa because that gives you around 13kPa of O2 partial pressure, which is normoxic. Anything below that is considered hypoxic. And on top of that, there's also a condition called absorption atelactis, where the alveolae collapse due to a lack of buffer gas, which happens when people breathe pure O2 or O2-enriched air for too long. Anaesthesia can also cause atelactis, which can be Game Over for certain medical conditions. Never mind plain old oxygen toxicity.

The practical limit of altitude adaptation is around 1850m. After that, complete adaptation is not really possible bar genetics. There are also a whole host of other long-term medical hazards due to chronic hypoxia, which are very similar to the effects of microgravity. Not something you want on a planet with 0.38g anyway.

The lower bound for pressures is around 0.5 bar, below which voice communication becomes harder, increase in air cooling ventilation size outstrips weight savings and so on, plus a 0.65 bar/34% O2 environment is all you need for a zero prebreathe in a modern suit. But the xEMU is going to be zero prebreathe from normoxic sea level pressure anyway.

Bioastronautics Handbook (1973): https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730006364.pdf
Bounding the Spacecraft Atmosphere Design Space for Future Exploration Missions (2005): http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.520.4888&rep=rep1&type=pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/05/2019 02:51 pm
Replying to a paraterraforming post in the Scaling Ag thread:

This seems like the thread. I've been talking to Dr Casey Handmer about his brilliant blog post:
https://caseyhandmer.wordpress.com/2019/11/28/domes-are-very-over-rated/
which builds on the essential insight that the Mars surface can be pressurised with Mars air to a suitable level for human habitation with what we've been calling a "bubble tent", or - if you want to get technical, a flexible mega-habitat.
The basic idea is to take a material like ETFE film, pin it down with steel cables, and inflate.

As soon as you look at the edges, it's just a dome (with all the associated issues) with internal tie-downs to flatter the roof. [edit: Oh what a lovely roof. {laughs} "Flatten", obviously.] Which we've discussed several times. Indeed, it essentially is a grid of domes joined at large cut-outs. I mean, what would the first "cell" look like? A dome. How would you add more "cells"? Same as you would join domes together.

There's nothing about anchoring a cluster of cables in the dimples that is inherently easier than anchoring cables around the rim of a dome, you are still focusing the entire uplift force on the roof into a small area, you are still putting multiple anchors into that small area (forcing you to go much deeper because there's less anchoring per linear metre when you cluster the anchors). I think the anchoring is actually worse in this design, more lift focused into a smaller area than a series of domes the size of each "cell".

Similarly, the author talks hand-wavingly about having internal bulkheads that will take the pressure between sections in an emergency. But seems to ignore that every one of those bulkheads needs to be engineered like the outside of a dome. And it has to work from both directions (since you don't know which side the emergency depressurisation will happen on.) Likewise, the "pressurised corridors" as safety shelters means you have to build them to exactly the standards you'd need if they were simply out on the Martian surface. (They also need airlocks. Otherwise the first person to close the door locks everyone else out.)

(Aside: Why steel cables? If the EFTE is capable of withstanding the forces, why not have the dimples touch the ground and be anchored themselves. Perhaps that would make the similarity with a dome too obvious. I did like the mention that if the roof was at 6km, steel cables would weigh the roof down without anchoring. That's the principle of "shell worlds".)

There's a bunch of other issues (what's the thermal loss through that roof? wouldn't condensation be continuous? etc etc) that aren't addressed.

Quote
On Mars, we can make do with lower pressure and enriched oxygen  [...] A 40 kPa atmosphere

Oops. Keep the air breathable at that pressure and your EFTE roof skin becomes nicely flammable. The roof, the roof, the roof is on fire...
Title: Re: Envisioning Amazing Martian Habitats
Post by: BZHSpace on 12/06/2019 08:07 am
Good news !

First the module concept will be release on Christmas, multiple floor plan, cross sections and renders will be put on the topic and available in PDF file with a description of the module. It will be decline in several version of the module, which are adapted to multiple uses for example: working, living, airlock, farming, sport and stocking.

On January the module will be completed with a proposition of assemblage of multiple module (the same one I will show you on Christmas).

On February the assemblage will be completed with many other cool things!

I will get you inform of the updates on my project!
Title: Re: Envisioning Amazing Martian Habitats
Post by: BZHSpace on 12/07/2019 01:36 pm
Double post I'm so sorry the moderator  :'(  :

I will show you my first concept model but of course not finished about the concept (I talked to you on the previous post) :

The model will be completed and add with some option at this point it's juste a proposition.

. picture 1 : one module with/without developable shell/isolation from radiation
. picture 2 : quick plan of assemblage of module/combinaison
. picture 3 : 1st model of a proposition of assemblage/combinaison
. picture 4 : 2nd model of a proposition of assemblage/combinaison
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/08/2019 06:51 pm
I mentioned a while ago the possibility of a modular base that might be assembled rather like a game.  So this week end I made a virtual board for it.  I don't expect to ever have this as a real game, but it's a fun though experiment.  The idea would be that your ships lands somewhere on the board according to a roll of dice. The dark pink parts are Glacier flows with water.  You build a road from your ship to the water, while setting up solar or nuclear power.
Dust storms could come along according to dice at each synod, favoring the nuclear rich or the solar rich.
Greenhouses could be added or not, balancing local production with supplies.
At each synod, ship(s) bring new settlers and new equipment.
The gameplay might be along the lines of 'take it easy', where everyone has their own identical boards, and as time goes on the impact of decisions add up.  I guess the first one to a certain size might be the winner, or after a set number of turns the  largest base, or the most self sufficient base would win.
As solar takes up too much space a a board, there would be a provision for a remote site, and a counter on the solar resource once you start hitting the edge of the board.
You would accumulate propellant to fuel return ships, to reduce costs and boost morale, if that was one of the game values.

There would be a lot of argument required to set the values of things in the game design!!!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/09/2019 05:56 am
From a tile-game strategy POV, you've trapped your core making expansion harder. I would've put the solar times on the other side of what I assume are the first two landers-cum-storage-tanks? Unless there a special resource tile in that area that hasn't been accessed yet but needs to be kept for future expansion once you level up your processing plant.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/09/2019 01:51 pm
From a tile-game strategy POV, you've trapped your core making expansion harder. I would've put the solar times on the other side of what I assume are the first two landers-cum-storage-tanks? Unless there a special resource tile in that area that hasn't been accessed yet but needs to be kept for future expansion once you level up your processing plant.
I almost always lose at board games.  Terrible at strategy.  In this case, I would expect that the solar panels could be moved to open up a road, at the cost of wasted energy and time. Guess that's one of the lessons this type of analysis might highlight :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 12/10/2019 01:30 pm
From a tile-game strategy POV, you've trapped your core making expansion harder. I would've put the solar times on the other side of what I assume are the first two landers-cum-storage-tanks? Unless there a special resource tile in that area that hasn't been accessed yet but needs to be kept for future expansion once you level up your processing plant.
I almost always lose at board games.  Terrible at strategy.  In this case, I would expect that the solar panels could be moved to open up a road, at the cost of wasted energy and time. Guess that's one of the lessons this type of analysis might highlight :-)
That's an important real life tradeoff as well. Do you site something close by, to make things more efficient now, and then move it later, or do you site it a ways out, at the cost of less effiicency now but no loss of production later. I bet you see that sort of thing in your work with mines all the time, Lamontagne...

Also, how many of you have played "Terraforming Mars" ? It's at the macro level and this base construction is at the micro level, but it does resonate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2019 04:53 pm
From a tile-game strategy POV, you've trapped your core making expansion harder. I would've put the solar times on the other side of what I assume are the first two landers-cum-storage-tanks? Unless there a special resource tile in that area that hasn't been accessed yet but needs to be kept for future expansion once you level up your processing plant.
I almost always lose at board games.  Terrible at strategy.  In this case, I would expect that the solar panels could be moved to open up a road, at the cost of wasted energy and time. Guess that's one of the lessons this type of analysis might highlight :-)
That's an important real life tradeoff as well. Do you site something close by, to make things more efficient now, and then move it later, or do you site it a ways out, at the cost of less effiicency now but no loss of production later. I bet you see that sort of thing in your work with mines all the time, Lamontagne...

Also, how many of you have played "Terraforming Mars" ? It's at the macro level and this base construction is at the micro level, but it does resonate.
I've got it at home, played twice, lost both times. It's way more ambitious though.  This is closer to a game called Megawatt, a resources and energy game.
Yes, mines are moving stuff around all the time and building temporary infrastructures.  In fact, a mine, today is entirely a temporary infrastructure.  With fly in fly out, there is nothing left once the mine is played out, the mining plant demolished and the site rehabilitated.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/10/2019 05:04 pm
Mining analogies raise the issue that it might make sense not to invest too much in fixed infrastructure during the first few years, with the idea that you may want to tear up the whole thing and move it to a more economical site.  Or wreck it and re-use the materials.  The limited lifetime of the habitats and their technologies might also favor mobile/recyclable installations.
Following the mining habits, you would have the exploration camp, that can be anywhere and is movable at will, more or less.  Then the construction camp, that is a a longer term infrastructure close to the permanent site once this has been identified.
And then the Mars colony/settlement itself, with all the trimmings and extensive in-situ production facilities.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/13/2019 12:51 pm
[snip]
Frequency would likely be DC, or possibly 400 Hz (for the same reasons it's used in aircraft).

Doesn't high frequency cause more losses in long range transmission compared to lower frequency?

Doh, yep. Thanks. HVDC it is?

It's rather an interesting question: what frequency would a grid use if starting with 21st century technology? 50-60 Hz was optimized for AC motors and incandescent lights (both rather inefficient by modern standards). But increasingly the grid is interacting with wall warts/chargers, LEDs, high efficiency digital motor controllers, battery chargers (possibly bidirectional) and solar inverters. The heart of all these is the switching power supply.

It seems like all of these switching power supplies would become simpler/cheaper/more efficient if the grid used DC, because the rectification and LF smoothing stages get deleted. But DC could have safety issues with arc termination.i would be curious what household voltage would be best for a DC grid.

These posts really should be moved to the power options thread...
This is a good read on the subject.  Not qualified to judge it in depth though, but I know our local utility is thinking along these lines for the 20-50 years horizon.
https://www.cepro.com/news/how_a_low-voltage_dc-powered_home_might_work_tesla_powerwall_energy_storage/

And yes, we should get back to amazing building here.

Edit/Lar: Most of the posts were moved to Power Options: https://forum.nasaspaceflight.com/index.php?topic=39785.0
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/14/2019 09:29 pm
Back to designing the Base!

Starting from a launch platform and landing pad combo. Would use the same 4 self propelled transporter units as used in Boca Chica to transport unfueled Starship.
The launch pad might be entirely made of metal if Mars concrete is not yet available.  All that is needed is a small cliff a few km from the base.
Self propelled transporters would mass 26 tonnes each unmodified, so no doubt we would have them purpose built for Mars.  Might be an issue getting them around the legs, but at least the flaps are no longer in the way.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/18/2019 01:45 am
Related post on ISRU X60 Airloy, targeting mass-production of lightweight, insulated, durable outdoor structures: 

Vanadium for X60 (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2026311#msg2026311)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 12/18/2019 05:30 pm
Related post on ISRU X60 Airloy, targeting mass-production of lightweight, insulated, durable outdoor structures: 

Vanadium for X60 (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2026311#msg2026311)
Interesting, but it's probably too early to be planning out exactly how we might refine potential construction materials on Mars as there are too many unknowns. Ore concentration, location, depth, substrate, particle size, composition of contaminants and the availability and recyclability of required reactants. All of these things and more will help determine which processes and which materials end up being used.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/18/2019 10:51 pm
Related post on ISRU X60 Airloy, targeting mass-production of lightweight, insulated, durable outdoor structures: 

Vanadium for X60 (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2026311#msg2026311)
Interesting, but it's probably too early to be planning out exactly how we might refine potential construction materials on Mars as there are too many unknowns. Ore concentration, location, depth, substrate, particle size, composition of contaminants and the availability and recyclability of required reactants. All of these things and more will help determine which processes and which materials end up being used.

"Plastic" shouldn't be a magic word.

More thought is needed here on ISRU plastics that can serve under martian conditions (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2025192#msg2025192).  X60 (http://www.airloy.com/category/productlines/) is cryogenically ductile, hence "plastic", and there is at least a sketch (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2026311#msg2026311) of an ISRU process.  That's a starting point, not a give-up point.  Improvements and alternates are interesting.

As for reactants, if you don't know where I sourced them, you can check the noted Red Gold (https://forum.nasaspaceflight.com/index.php?topic=45772.msg1859890#msg1859890) posts to see for yourself.  Red Gold reactants would be assembled in a for-profit, scalable industry; that's why you'd expect those reactants to be abundant, and available for use in other, complementary ventures such as ISRU power systems and ISRU construction.  That, too, is a sketch, and a starting point.  Likewise.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/19/2019 11:50 am
After seeing how terrible Mars dust is at shielding, I went back and looked at some possible hydrated minerals on Mars to use as high-density shielding. Gibbsite (Al(OH)3) did pretty well, and even Goethite (FeOH) was ok. But gypsum (CaSO4.2H2O) is common on Mars, there being entire dunes of it at high northern latitudes and it's dense - around 2.6g/cm3. Plus it has been a building material since antiquity. On a cm to cm basis, it outperforms water. A Mars building need only be thick-walled in appearance (say 1.5m to 1.75m of gypsum) to achieve high levels of radiation shielding (<5.5mSv/day). Further interior walls and thicker overhead shielding (2.3m of gypsum or 5m of water) could take care of the rest. 500g/cm2 of water is equivalent to 600g/cm2 of gypsum.

One thing to note is that the interiors of any habitats need to have about 10g/cm2 of hydrogen-rich shielding on the floor to cut down on the backscatter from the regolith.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/19/2019 02:47 pm
the interiors of any habitats need to have about 10g/cm2 of hydrogen-rich shielding on the floor to cut down on the backscatter from the regolith.

If you store several meters of water on the roof, there's no regolith backscatter radiation to protect against, and no need for other shield material, whether under the floor or on the roof.

You might try it in OLTARIS (https://spaceradiation.larc.nasa.gov/oltaris.html).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/19/2019 04:19 pm
Even for several metres of water, (eg 500g/cm2) it is still true. I worked this out in OLTARIS which is why I'm saying this.

Accepting the increased dose is an option, but cutting down on backscatter is an important part of the shielding design toolbox, especially for thinner-walled habs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/19/2019 05:31 pm
Even for several metres of water, (eg 500g/cm2) it is still true. I worked this out in OLTARIS which is why I'm saying this.

There's no significant regolith backscatter under 5 m of water.  Share your work, and show the actual backscatter.

Accepting the increased dose is an option...

ISS crews incur 0.44 - 0.89 mSv/day (http://spaceflight.nasa.gov/spacenews/factsheets/pdfs/radiation.pdf), far below NASA's limit of 1000 mSv/year.  And in your plot, even 10 cm of water gives a dose lower than ISS dose.  But you demand more than 5 m of water, so you got confused there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/19/2019 08:05 pm
Even for several metres of water, (eg 500g/cm2) it is still true. I worked this out in OLTARIS which is why I'm saying this.
There's no significant regolith backscatter under 5 m of water.  Share your work, and show the actual backscatter.

As I've said before: Stop telling other people to do things that you won't do yourself.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/19/2019 08:25 pm
Even for several metres of water, (eg 500g/cm2) it is still true. I worked this out in OLTARIS which is why I'm saying this.
There's no significant regolith backscatter under 5 m of water.  Share your work, and show the actual backscatter.

As I've said before: Stop telling other people to do things that you won't do yourself.

Quote from: Lear
"Nothing will come of nothing."

A transmitted radiation dose that's comparable to airliner dose isn't going to produce significant backscatter.  But he can paste his OLTARIS backscatter result; the mistake should show.

Can anyone with access to OLTARIS answer a question...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/22/2019 03:15 pm
If I'm wrong, then point out to me how I fade the mistake. I made one about the shielding model a while back.

A backstop of 10g/cm2 is a fair amount of backscatter protection... I got a 30%ish reduction from that. But it may be more mass-effective to add more shielding and then a small backstop. But as demonstrated below, even behind 500g/cm2 or 5m of water, the effect of regolith is significant: a dose increase of about 60%, specifically 0.1 mSv/day (no backstop) vs 0.06 mSv/day (50g/cm2 backstop). 50g/cm2 backstop size is me simplifying the issue for demonstration.

The white line is the dose in tissue, ICRP 60, measured behind 500g/cm2 of water shielding and 20g/cm2 of Martian atmosphere (which I clip in the Excel plot to avoid confusion). No backstop has 300g/cm2 regolith (the Thickness model accounts for the Mars surface this way with the OLTARIS default mix). Backstop has 50g/cm2 PE followed by 250/cm2 regolith; from the convergence of the lines, the difference between 250g/cm2 and 300g/cm2 can be seen as small for this rough sketch.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/22/2019 03:56 pm
Is there a good value for the lighting required for a public area on Mars?

The sun provides about 1000 W/m2 on Earth.  That's a peak value and probably really uncomfortable for humans.
On the other end of the spectrum, lighting in buildings can be around 5-20 W/m2 and we see quite well.
There is plenty of evidence showing that lighting levels that are too low lead to depression in many people.

It's also well known that plants need to be stirred by wind for proper development, and that most plants in low lighting conditions die or at least don't do all that well, or develop very slowly.

So what might be the lighting level required in public spaces of a Martian settlement? In particular those that we want to people with plants so that they look good?   And are there any studies to back up the numbers?  At this point I'm thinking about 130 W/m2 as a value that is close to 'full daylight'..  Because less that that is overcast sky, and that doesn't sound encouraging, in the long term.
For domes, the 600 W/m2 of Mars will go down really fast through thick glass/plastic/water, and there are bound to be opaque structural elements, and the actual surface illumination due to dust is already well bellow 600, so should we expect even the simplest Martian dome to have some extra artificial lighting?

By the way removing the energy from 130 W/m2 is not a simple task, but might tie in nicely with the need for some wind in the settlement.
BTW if we come to a consensus on this the number will go to Marspedia Lighting : https://marspedia.org/Lighting#Lighting_levels

That needs a bit of work to be a useful reference.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/22/2019 04:06 pm
After seeing how terrible Mars dust is at shielding, I went back and looked at some possible hydrated minerals on Mars to use as high-density shielding. Gibbsite (Al(OH)3) did pretty well, and even Goethite (FeOH) was ok. But gypsum (CaSO4.2H2O) is common on Mars, there being entire dunes of it at high northern latitudes and it's dense - around 2.6g/cm3. Plus it has been a building material since antiquity. On a cm to cm basis, it outperforms water. A Mars building need only be thick-walled in appearance (say 1.5m to 1.75m of gypsum) to achieve high levels of radiation shielding (<5.5mSv/day). Further interior walls and thicker overhead shielding (2.3m of gypsum or 5m of water) could take care of the rest. 500g/cm2 of water is equivalent to 600g/cm2 of gypsum.

One thing to note is that the interiors of any habitats need to have about 10g/cm2 of hydrogen-rich shielding on the floor to cut down on the backscatter from the regolith.
Gypsum blocks construction on Mars?  https://en.wikipedia.org/wiki/Gypsum_block
Seems like an interesting and simple building material.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KSHavre on 12/22/2019 05:15 pm
After seeing how terrible Mars dust is at shielding, I went back and looked at some possible hydrated minerals on Mars to use as high-density shielding. Gibbsite (Al(OH)3) did pretty well, and even Goethite (FeOH) was ok. But gypsum (CaSO4.2H2O) is common on Mars, there being entire dunes of it at high northern latitudes and it's dense - around 2.6g/cm3. Plus it has been a building material since antiquity. On a cm to cm basis, it outperforms water. A Mars building need only be thick-walled in appearance (say 1.5m to 1.75m of gypsum) to achieve high levels of radiation shielding (<5.5mSv/day). Further interior walls and thicker overhead shielding (2.3m of gypsum or 5m of water) could take care of the rest. 500g/cm2 of water is equivalent to 600g/cm2 of gypsum.

One thing to note is that the interiors of any habitats need to have about 10g/cm2 of hydrogen-rich shielding on the floor to cut down on the backscatter from the regolith.
Gypsum blocks construction on Mars?  https://en.wikipedia.org/wiki/Gypsum_block
Seems like an interesting and simple building material.

The Wiki article says Gypsom blocks are internal non-load bearing; so external walls would have an outer load bearing layer, and internal layer of Gypsom blocks for protection? Maybe thick enough for the nominal radiation environment, and then internal walls made of Gypsom. Bedrooms and emergency supplies towards the center of the structure to ride out any rad storms!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/22/2019 06:15 pm
The Wiki article says Gypsom blocks are internal non-load bearing; so external walls would have an outer load bearing layer, and internal layer of Gypsom blocks for protection?

Other way around. You seem to get the best radiation protection from having the good stuff on the outside. In this case, you'd put have a shell of gypsum blocks outside the pressure-vessel. And the pressure vessels can support metres deep layers of blocks without issue. This also gives you extra thermal mass for the pressure-vessel walls. (Obviously, you can just pile gypsum loosely, but bricks give you better shape optimisation.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/22/2019 06:29 pm
The Wiki article says Gypsom blocks are internal non-load bearing; so external walls would have an outer load bearing layer, and internal layer of Gypsom blocks for protection?

Other way around. You seem to get the best radiation protection from having the good stuff on the outside. In this case, you'd put have a shell of gypsum blocks outside the pressure-vessel. And the pressure vessels can support metres deep layers of blocks without issue. This also gives you extra thermal mass for the pressure-vessel walls. (Obviously, you can just pile gypsum loosely, but bricks give you better shape optimisation.)
You could also use the blocks inside, rather than concrete blocks, for partitions.  Might make for a very white colored habitat, seen from the outside?  A bit mediterranean, perhaps?
Title: Re: Envisioning Amazing Martian Habitats
Post by: alexterrell on 12/22/2019 06:30 pm
Is there a good value for the lighting required for a public area on Mars?

The sun provides about 1000 W/m2 on Earth.  That's a peak value and probably really uncomfortable for humans.
On the other end of the spectrum, lighting in buildings can be around 5-20 W/m2 and we see quite well.
There is plenty of evidence showing that lighting levels that are too low lead to depression in many people.

It's also well known that plants need to be stirred by wind for proper development, and that most plants in low lighting conditions die or at least don't do all that well, or develop very slowly.

So what might be the lighting level required in public spaces of a Martian settlement? In particular those that we want to people with plants so that they look good?   And are there any studies to back up the numbers?  At this point I'm thinking about 130 W/m2 as a value that is close to 'full daylight'..  Because less that that is overcast sky, and that doesn't sound encouraging, in the long term.
For domes, the 600 W/m2 of Mars will go down really fast through thick glass/plastic/water, and there are bound to be opaque structural elements, and the actual surface illumination due to dust is already well bellow 600, so should we expect even the simplest Martian dome to have some extra artificial lighting?

By the way removing the energy from 130 W/m2 is not a simple task, but might tie in nicely with the need for some wind in the settlement.
BTW if we come to a consensus on this the number will go to Marspedia Lighting : https://marspedia.org/Lighting#Lighting_levels

That needs a bit of work to be a useful reference.
Most of the sunlight is infrared, which is not really useful (except for keeping you warm).

https://greenbusinesslight.com/resources/lighting-lux-lumens-watts/

gives: Lobbies, Public Corridors, Stairwells   200 Lux

This is the same as 200 Lumen per square metre. LEDs are about 100 Lumens per Watt. Hence you need about 2 Watts per square metre to give good lighting for humans. I've just fitted my home office with 40W of LEDs for about 25 square metres, and it's pretty bright. (Though I might add a desk light if I want to do fine work).

The site also gives: Ambient Daylight   10,000 to 25,000

(This site gives even more specific lighting levels: https://www.engineeringtoolbox.com/light-level-rooms-d_708.html)

That then translates to 100 to 250 Watts per square metre and might be desirable in some areas, e.g. agriculture, and perhaps "sun rooms".

(I made a suggestion a long time ago that a Mars colony might want to invest in some sun lamps - perhaps even a sun tanning bed used by each colonist for 15 minutes per week)

The Marspedia article states "Most lightbulbs on Earth are incandescent". That might still be true, but I bought some lights at the DIY store the other day, and I'd say they were 90% LED and 10% flourescent tubes. (That is in Germany, the USA may be a bit behind) I haven't seen an incandescent on sale recently and haven't bought one for over a decade (aside from an oven lamp). For Mars, I would assume LEDs, unless something better comes along.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/22/2019 07:09 pm
Is there a good value for the lighting required for a public area on Mars?

The sun provides about 1000 W/m2 on Earth.  That's a peak value and probably really uncomfortable for humans.
On the other end of the spectrum, lighting in buildings can be around 5-20 W/m2 and we see quite well.
There is plenty of evidence showing that lighting levels that are too low lead to depression in many people.

It's also well known that plants need to be stirred by wind for proper development, and that most plants in low lighting conditions die or at least don't do all that well, or develop very slowly.

So what might be the lighting level required in public spaces of a Martian settlement? In particular those that we want to people with plants so that they look good?   And are there any studies to back up the numbers?  At this point I'm thinking about 130 W/m2 as a value that is close to 'full daylight'..  Because less that that is overcast sky, and that doesn't sound encouraging, in the long term.
For domes, the 600 W/m2 of Mars will go down really fast through thick glass/plastic/water, and there are bound to be opaque structural elements, and the actual surface illumination due to dust is already well bellow 600, so should we expect even the simplest Martian dome to have some extra artificial lighting?

By the way removing the energy from 130 W/m2 is not a simple task, but might tie in nicely with the need for some wind in the settlement.
BTW if we come to a consensus on this the number will go to Marspedia Lighting : https://marspedia.org/Lighting#Lighting_levels

That needs a bit of work to be a useful reference.
Most of the sunlight is infrared, which is not really useful (except for keeping you warm).

https://greenbusinesslight.com/resources/lighting-lux-lumens-watts/

gives: Lobbies, Public Corridors, Stairwells   200 Lux

This is the same as 200 Lumen per square metre. LEDs are about 100 Lumens per Watt. Hence you need about 2 Watts per square metre to give good lighting for humans. I've just fitted my home office with 40W of LEDs for about 25 square metres, and it's pretty bright. (Though I might add a desk light if I want to do fine work).

The site also gives: Ambient Daylight   10,000 to 25,000

(This site gives even more specific lighting levels: https://www.engineeringtoolbox.com/light-level-rooms-d_708.html)

That then translates to 100 to 250 Watts per square metre and might be desirable in some areas, e.g. agriculture, and perhaps "sun rooms".

(I made a suggestion a long time ago that a Mars colony might want to invest in some sun lamps - perhaps even a sun tanning bed used by each colonist for 15 minutes per week)

The Marspedia article states "Most lightbulbs on Earth are incandescent". That might still be true, but I bought some lights at the DIY store the other day, and I'd say they were 90% LED and 10% flourescent tubes. (That is in Germany, the USA may be a bit behind) I haven't seen an incandescent on sale recently and haven't bought one for over a decade (aside from an oven lamp). For Mars, I would assume LEDs, unless something better comes along.
I agree on most of this.  The specific question might be re-framed as:  Should we try to make the Settlement more Earth like by providing extra lighting in the corridors, close to sunlight levels, rather than the minimum values found in lighting handbooks.  A large part of why motel corridors and public housing buildings are so depressing is that the are so badly lit.  I think we want to avoid the motel corridor effect, and we would like plants in public spaces to thrive, not just survive.  So perhaps even more than 130W/m2?

I've adapted the article to take the actual phase out of incandescent lights into account.  See the wikipedia article : https://en.wikipedia.org/wiki/Phase-out_of_incandescent_light_bulbs
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 12/22/2019 07:39 pm
Especially if you want children to grow up in the colony, then at least some space should be lit up with full solar intensity. It may be important for proper eye development.

https://www.nytimes.com/2017/01/19/well/live/for-better-vision-let-the-sunshine-in.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/22/2019 07:50 pm
Especially if you want children to grow up in the colony, then at least some space should be lit up with full solar intensity. It may be important for proper eye development.

https://www.nytimes.com/2017/01/19/well/live/for-better-vision-let-the-sunshine-in.html
Exactly.  But how much outdoors is enough outdoors?  A lot of us pass our lives is fairly dark offices, is that really the best solution for us?  Or is it a kind of holdover from the 'worker as a production unit" mentality, that offers the minimum economical, rather than the minimum vital?  I think the real outdoors on Mars will be rarely visited, unless there are immense transformations is spacesuits, so we need to create an outdoors indoors.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Barley on 12/22/2019 08:20 pm

I agree on most of this.  The specific question might be re-framed as:  Should we try to make the Settlement more Earth like by providing extra lighting in the corridors, close to sunlight levels, rather than the minimum values found in lighting handbooks.  A large part of why motel corridors and public housing buildings are so depressing is that the are so badly lit.  I think we want to avoid the motel corridor effect, and we would like plants in public spaces to thrive, not just survive.  So perhaps even more than 130W/m2?

You'd probably want any particularly brightly lit areas to be places people would linger rather than corridors.  Cafes, sports areas, perhaps a botanical garden (which may be distinct from industrial green houses).  Even if you want to avoid dim corridors, there is still a huge gap between a brightly lit corridor and something approaching daylight.



On earth many office areas are less than ideal for plants.  Plants are often rotated between the office and a green house which lets them recover.  The same solution could be used on Mars if you want plants for ambience.

Also you should measure illumination in lumen, candela and lux rather than Watts.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/22/2019 09:19 pm

I agree on most of this.  The specific question might be re-framed as:  Should we try to make the Settlement more Earth like by providing extra lighting in the corridors, close to sunlight levels, rather than the minimum values found in lighting handbooks.  A large part of why motel corridors and public housing buildings are so depressing is that the are so badly lit.  I think we want to avoid the motel corridor effect, and we would like plants in public spaces to thrive, not just survive.  So perhaps even more than 130W/m2?

You'd probably want any particularly brightly lit areas to be places people would linger rather than corridors.  Cafes, sports areas, perhaps a botanical garden (which may be distinct from industrial green houses).  Even if you want to avoid dim corridors, there is still a huge gap between a brightly lit corridor and something approaching daylight.



On earth many office areas are less than ideal for plants.  Plants are often rotated between the office and a green house which lets them recover.  The same solution could be used on Mars if you want plants for ambience.

Also you should measure illumination in lumen, candela and lux rather than Watts.
I'm not measuring the illumination, I'm measuring the power required to create it, and the power that needs to be removed from the space once it's been 'used'.  I totally agree that's not illumination per se.  I'm presuming LED technology, with properly tuned wavelengths, whatever they may be.
I absolutely want plants for ambiance.  And as something t keep the mind busy.  My ideal is Estepona, in Spain, that seems to me the perfect mix.
I think production greenhouses will not be very comfortable for humans.  Rather like standing in a jungle, or the middle of a corn field in the heart of summer.  Production greenhouses may also be subject to radical temperature and atmospheric  gas content swings. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: tbellman on 12/22/2019 09:26 pm
The Marspedia article states "Most lightbulbs on Earth are incandescent". That might still be true, but I bought some lights at the DIY store the other day, and I'd say they were 90% LED and 10% flourescent tubes. (That is in Germany, the USA may be a bit behind) I haven't seen an incandescent on sale recently and haven't bought one for over a decade (aside from an oven lamp).

Sales of incandescent light bulbs is illegal in the European Union.  Regulations started taking effect in 2009, and has gradually become stricter.  Large parts of the rest of the world, including the US of America, have also restricted or outlawed their sales.  (There tend to be exceptions for several purposes, though, e.g. oven lamps.)  So it's not very surprising that you haven't seen many in stores lately. :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/23/2019 02:47 pm
A backstop of 10g/cm2 is a fair amount of backscatter protection... I got a 30%ish reduction from that.

The plot should be cleaner, but we see that the backscatter is insignificant.  With 5 m of water shielding, your plotted backscatter is ~ .04 mSv/day.  Here both transmitted dose and backscatter dose are airliner dose (https://www.cdc.gov/nceh/radiation/air_travel.html), insignificant. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/23/2019 03:44 pm
A backstop of 10g/cm2 is a fair amount of backscatter protection... I got a 30%ish reduction from that.

The plot should be cleaner, but we see that the backscatter is insignificant.  With 5 m of water shielding, your plotted backscatter is ~ .04 mSv/day.  Here both transmitted dose and backscatter dose are airliner dose (https://www.cdc.gov/nceh/radiation/air_travel.html), insignificant. 

In other words, you thought that I thought that some regolith would magically crank up the dose to near-Mars surface levels again?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/23/2019 03:53 pm
A backstop of 10g/cm2 is a fair amount of backscatter protection... I got a 30%ish reduction from that.

The plot should be cleaner, but we see that the backscatter is insignificant.  With 5 m of water shielding, your plotted backscatter is ~ .04 mSv/day.  Here both transmitted dose and backscatter dose are airliner dose (https://www.cdc.gov/nceh/radiation/air_travel.html), insignificant. 

In other words, you thought that I thought that some regolith would magically crank up the dose to near-Mars surface levels again?

Airliner radiation dose would be insignificant, requiring no shielding: e.g. no "shielding on the floor to cut down on the backscatter from the regolith".  Do you see that?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/23/2019 04:35 pm
Here's a nice spot for significant dose, whatever the scattering is  ;D
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/23/2019 06:09 pm
Not quite to scale, but pretty close.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/28/2019 12:16 am
A new shape for the Space Settlement: The semi cylindrical polyhedron.  Makes a quasi flat floor without requiring anchoring for a dome like structure.
By James D. Lowe
From my Christmas present : The new fields of Space Architecture  :-)

A number of these could be connected together, requiring some for of structural webbing between the elements.
Basically, L=r/2.  So a 5m radius shape would be 2.5m long.

Not certain this is all that much better than a tube with a tensile floor, but its fun to see a new shape.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/28/2019 01:47 am
A new shape for the Space Settlement: The semi cylindrical polyhedron.  Makes a quasi flat floor without requiring anchoring for a dome like structure.
By James D. Lowe
From my Christmas present : The new fields of Space Architecture  :-)

A number of these could be connected together, requiring some for of structural webbing between the elements.
Basically, L=r/2.  So a 5m radius shape would be 2.5m long.

Not certain this is all that much better than a tube with a tensile floor, but its fun to see a new shape.

I'm confused. Seeking more information I tracked down James Lowe's original paper on the subject (freely available), but it only raises more questions.

At first he does mylar models showing a novel tensile geometry that can (seemingly) have a flat floor without additional restraint (or even heavier, large floor beams to resist the flat floor's bending moment). But then the paper goes on to specify... a large beam (actually not a 1D beam, but a 2D honeycomb structure) sufficient to resist the bending moments on the floor. So which is it?

My "cellular hab" design by contrast can give a flat floor in pure tension and with a minimum of awkward curved corner volume.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/28/2019 12:47 pm
A new shape for the Space Settlement: The semi cylindrical polyhedron.  Makes a quasi flat floor without requiring anchoring for a dome like structure.
By James D. Lowe
From my Christmas present : The new fields of Space Architecture  :-)

A number of these could be connected together, requiring some for of structural webbing between the elements.
Basically, L=r/2.  So a 5m radius shape would be 2.5m long.

Not certain this is all that much better than a tube with a tensile floor, but its fun to see a new shape.



Reminds me of the recent inflatable airlock concepts. I think the main advantage is that you can fold it at radius R and then unfold it for 2R on the floor, along with a nice flat floor.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/28/2019 03:31 pm
Building structural components for pressure vessels from ice will be impossible though. Melting caves in a glacier not so much. You will have to have enough ice above and around you to counter 10t per square meter of pressure if you want to build with ice.

Meltwater rodwells give some useful numbers: 

- On Earth, 50 m rodwell depth gives closure and water containment. 

- Beyond that, one rodwell extending from 60 - 100 m depth successfully withstood a TNT blast (https://forum.nasaspaceflight.com/index.php?topic=44508.msg1935408#msg1935408), handling pressures far in excess of the nominal requirement of 10 t per m2.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/28/2019 04:22 pm
I tracked down James Lowe's original paper on the subject

Danke schön, Señor. (My first thought when I saw his row-of-connected-arches design was that he's trending towards your internal web cellular cube idea.)

My "cellular hab" design by contrast can give a flat floor in pure tension and with a minimum of awkward curved corner volume.

Have you tried publishing your design?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Semmel on 12/29/2019 08:31 pm
Did anyone ever analyse the properties of a torus as a pressure vessel for living quarters on Mars? I think it would be quite an obvious candidate since it is much flatter than a tall dome for the same floor area. It should not be all that much worse than a sphere in terms of volume per wall thickness. One could stack tori (toruses?) or place them with much larger outer radius but the same tube diameter inside each other to fill in the central hole. Or one could not do this to keep the sky light inside.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/29/2019 09:44 pm
Did anyone ever analyse the properties of a torus as a pressure vessel for living quarters on Mars? I think it would be quite an obvious candidate since it is much flatter than a tall dome for the same floor area. It should not be all that much worse than a sphere in terms of volume per wall thickness. One could stack tori (toruses?) or place them with much larger outer radius but the same tube diameter inside each other to fill in the central hole. Or one could not do this to keep the sky light inside.
The Spacehab/Bigelow module is a kind of inflatable torus with a rigid core. there are many variations on this and seme pretty detailed designs.  But I expect you're thinking bigger than this!

O'Neil studied toruses, cylinders, dumbbells and spheres in space, and Torus did have a lot of good points.  His main objection was the lack of a far horizon, if I recall correctly.  Multiples torus will end up as a case/variation of Twark_Main's repeating cellular structures, I expect.
Compared to tubes, you don't have the problem of the ends, but you do have a lot of double curved walls that are not ideal for habitation.
Toruses (tori?) have less wasted space than domes, unless the domes are large enough to be filled with independent structures and floors, and then the sphere, as a pressure vessel, will win out on the basis of less materials required and lower hoop stress than all the other structures.
The hoop stress and longitudinal stress in a torus are the same as for a long cylinder.  https://bit.ly/2QsvU8J

A torus would be an obvious solution for a habitat with a centrifugal living area.  This may be required if low gravity turns out to be a limitation.  See Kent Nebergall's excellent entry for the MArs Settlement design competition:
https://macroinvent.com/wp-content/uploads/2019/03/Eureka-Mars-Settlement-Concept.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/03/2020 07:23 pm
In the Off-Earth modification thread NSF-member Ludus bust suggested modifying Starships to make the tanks into habitable space. I'd say that could be quite useful on Mars. I'm thinking Starship "high-rises".

Such high-rises would still have a good amount of habitable space after radiation-protection had been installed, wouldn't they?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/04/2020 03:09 am
In the Off-Earth modification thread NSF-member Ludus bust suggested modifying Starships to make the tanks into habitable space. I'd say that could be quite useful on Mars. I'm thinking Starship "high-rises".

Such high-rises would still have a good amount of habitable space after radiation-protection had been installed, wouldn't they?

Sure, in particular if the radiation protection was water.  One has to wonder what the effort required would be compared to setting up an inflatable buried habitat though.  Perhaps they might best serve as water tanks?
In my experience, extensive modifications to an existing infrastructure can end up costing almost as much as something new.  Adding the tanks adds about 1100 m3 of volume. 
In the slightly longer term, a large roadheader can, in perfect conditions, produce 300 m3 per hour.  In reality, it's closer to 30 m3 per hour. Still, that's something like 300+ m3 per day.  In a year, it could dig, perhaps, 60 000 m3? 
So although I think that a Starship might make a novelty item kind of habitat, bringing a roadheader and identifying adequate rock formations is much more important for a 'real' settlement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/04/2020 06:08 am
I totally agree, lamontagne. A Starship high-rise vs. roadheading/tunelling would be for two very different periods in base expansion, the high-rise coming much earlier in the process.

The question is whether a high-rise would be needed before underground construction takes off. It could be an insurance policy if the digging proves more difficult than planned.

Very good point about the issues with refurbishing/modifying.

I am having weird visions now, of settlers living in tank bulkhead yurts... :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 01/04/2020 08:25 am
Here is what bothers me: Starship high-rise would have very poor GCR radiation protection. With a metal skin, it could be even worse than being outside due to secondary radiation. How about laying the Starship on the side and burying with soil? Could the structure handle that, maybe with internal columns added?

As for roadheader excavated space, I think you need to have an airtight seal on the walls. So this is a medium-term solution IMHO, not something that will be done during first few synods.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/04/2020 10:05 am
Airtight seal might not be necessary, depending on the rock. Could perhaps even be sprayed on.

As for the tunnel entrance perhaps a Starship tank bulkhead could be repurposed for a plug.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 01/04/2020 07:06 pm
How about laying the Starship on the side and burying with soil? Could the structure handle that

If the internal air pressure is even close to habitable, then yes. You could dump ten metres of regolith over it, no columns required.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 02/08/2020 04:50 pm
I totally agree, lamontagne. A Starship high-rise vs. roadheading/tunelling would be for two very different periods in base expansion, the high-rise coming much earlier in the process.

The question is whether a high-rise would be needed before underground construction takes off. It could be an insurance policy if the digging proves more difficult than planned.

Very good point about the issues with refurbishing/modifying.

I am having weird visions now, of settlers living in tank bulkhead yurts... :-)

On whether a different mode of construction is needed before underground construction takes off: two insurance policies in case of digging difficulties would be (1) to provide more energy and more equipment (in quantity and diversity), so that they can overcome the difficulties and/or (2) to have a backup plan for simpler underground habitats.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Genial Precis on 02/08/2020 06:33 pm
Let me make a simple-minded suggestion. SpaceX is already demonstrating one of the industrial answers to the problem of making a lot of pressurized volume quickly: tank-building machines. Suppose your basic habitat isn't a Starship, but a 70m tall 9m diameter pressure vessel made of 1 mm steel (mass 18 t).

1) Weld it up in the vertical position
2) Pressurize it
3) Tip it over onto a carrier
4) Wheel it over to where it needs to be
5) Hook it up to the rest of the hab
6) Bury it in as much dirt as needed for shielding from radiation (and anything that might puncture it!)

No, it's not as efficient per pressurized volume as some of the suggestions, but a manufacturing technique that's three times as productive probably takes precedence over a product that's twice as efficient. This design scores .25 m^3/kg on just the pressure vessel. It seems definitely tolerable if you have ISRU steel, but I don't know if it's in the right ballpark if you have to ship the steel (probably stainless if you're shipping it).

Has anyone made a credible pressurized volume budget?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2020 01:47 am
Let me make a simple-minded suggestion. SpaceX is already demonstrating one of the industrial answers to the problem of making a lot of pressurized volume quickly: tank-building machines. Suppose your basic habitat isn't a Starship, but a 70m tall 9m diameter pressure vessel made of 1 mm steel (mass 18 t).

1) Weld it up in the vertical position
2) Pressurize it
3) Tip it over onto a carrier
4) Wheel it over to where it needs to be
5) Hook it up to the rest of the hab
6) Bury it in as much dirt as needed for shielding from radiation (and anything that might puncture it!)

No, it's not as efficient per pressurized volume as some of the suggestions, but a manufacturing technique that's three times as productive probably takes precedence over a product that's twice as efficient. This design scores .25 m^3/kg on just the pressure vessel. It seems definitely tolerable if you have ISRU steel, but I don't know if it's in the right ballpark if you have to ship the steel (probably stainless if you're shipping it).

Has anyone made a credible pressurized volume budget?
I have a spreadsheet.  Don't know if it is credible, but it could be tweaked to be, I expect.
I've found about 720 $per m3 using only in-situ materials and about 1600 $per m3 with materials from Earth.

It's for cave dug by roadheader, with a locally produced lining of molten rock tiles, supported by the wall.
There is a section for carbon based liners from Earth, but these could be replaced by stainless steel.

Stainless steel on Earth is about 5$ per kg.
Locally produced stainless steel required about 57 MJ/kg (embodied energy).  At, let's say, 0,2$ per MJ, that's about 12 $ per kg on Mars for the energy alone.  You would need to add equipment and financing to get some kind of value.
If cargo to Mars is 500$ per kg, there is a lot of space there to make local production viable.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2020 02:07 am
The Boring Company Las Vegas tunnel is about 1,6 km long and 4m wide so about 19 000 m3.  There are two, so the whole project is  about 40 000 m3.
Musk said the budget for the tunnels was 10 000 000$, so that's about 250$ per m3.

It would seem they will take about six months for the tunnels, so about 40 000 / 180 = 220 m3 per day, or a bit less than 10 m3 per hour.

This is for an entirely lined tunnel, good for 4 bars.  Of course there is a cement plant somewhere, making the lining, and a steel plant making the rebar and cables that hold the lining in place.

So that might be something of a benchmark.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Genial Precis on 02/09/2020 03:30 am
This is all quite interesting. Although, I find dollar values difficult to use in this context explicitly because we're talking about Mars, where you can't convert your dollars into useful goods by purchasing this thing or the other. I think first you have to work out at least roughly, what's going to be sent and what's going to be done with it before money units start to become meaningful.

For example, the labor price is far too low. The point of all this expensive shipping is to support people, and the price of labor has to reflect that in order to be realistically accounted for. I'll have to think about it more carefully.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/09/2020 09:08 am
tank-building machines. Suppose your basic habitat isn't a Starship, but a 70m tall 9m diameter pressure vessel made of 1 mm steel (mass 18 t).
1) Weld it up in the vertical position
2) Pressurize it
3) Tip it over onto a carrier
4) Wheel it over to where it needs to be

Is there a reason (other than "SpaceX did it") for doing the assembly vertically rather than horizontally? Horizontal construction allows you to build in place, avoiding both the tip-over and the 70m long carrier.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Genial Precis on 02/09/2020 12:40 pm
Is there a reason (other than "SpaceX did it") for doing the assembly vertically rather than horizontally? Horizontal construction allows you to build in place, avoiding both the tip-over and the 70m long carrier.
Yes, my reason was that 1 mm stainless is floppy, so I didn't want it on its side until it was pressurized. Rather than a 70m carrier, I would assume a much smaller carrier supporting at either end would make more sense for this scheme.

Building in place means you have to cart around all the module-building equipment. If you can build modules of low enough mass to cart those around instead, it may make sense to build the modules centrally.

Each module will have some internal pieces. Assembling those at the same time as the pressure vessel or not is another consideration. If you want it to be easy to ship things around inside the pressure volume you have to design for that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/09/2020 01:53 pm
This is all quite interesting. Although, I find dollar values difficult to use in this context explicitly because we're talking about Mars, where you can't convert your dollars into useful goods by purchasing this thing or the other. I think first you have to work out at least roughly, what's going to be sent and what's going to be done with it before money units start to become meaningful.

I think this reasoning is flawed, and that a valuable analytical tool is being unnecessarily discarded. You certainly will be able to "convert your dollars into useful goods by purchasing this thing or the other," from both Martian and terrestrial suppliers. High shipping cost/delay doesn't change that.

Actual prices themselves will be very different of course, but there is still fundamentally an economy. Look at the economies in island nations, or even prisons.

For example, the labor price is far too low. The point of all this expensive shipping is to support people, and the price of labor has to reflect that in order to be realistically accounted for. I'll have to think about it more carefully.

I don't think this economic assumption necessarily holds. Is the "labor price" of the ISS astronauts sufficient to pay for the expensive shipping to support those people? Why or why not?

Surely some will be tempted at this point to reply with special pleading, saying, "but the ISS is a government research station not a colony," but the point is that there's no hard-and-fast rule saying that a colony must pay for itself with labor cost. If the ISS furnishes one exception, there are probably more.

Heck, look at Iridium's bankruptcy. More proof that the price doesn't "have to" reflect those expensive shipping costs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Genial Precis on 02/09/2020 04:08 pm
I think this reasoning is flawed, and that a valuable analytical tool is being unnecessarily discarded. You certainly will be able to "convert your dollars into useful goods by purchasing this thing or the other," from both Martian and terrestrial suppliers. High shipping cost/delay doesn't change that.
Oh, by no means did I mean to imply that dollars as an analytical tool should be discarded. Like, if I take it overly abstract and imagine some functional for "number of people supported" under constraints like "X set of minimal food per person" and "Y amount of pressurized volume per person" and so on, and maximize with respect to allocation of equipment and labor, that analysis would clearly produce lagrange multipliers giving you the marginal cost of this that and the other.

Such a functional would presumably be the output of a fairly specific plan, though. So my approach to the problem would be to start with a plan of what's being shipped and what's done with it, in order to work out the right order of magnitude for prices of things. If you pick $100/hr for labor and keep importing people until you fill all the things that would use labor if it really cost so little, you probably have too many people, and need to start your plan over with a higher labor rate.

Mars predictably will have price distortions, and I don't have a clear idea of which things and by how much. Because I don't even have a base case credible colony scheme in mind.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2020 05:43 pm
I think this reasoning is flawed, and that a valuable analytical tool is being unnecessarily discarded. You certainly will be able to "convert your dollars into useful goods by purchasing this thing or the other," from both Martian and terrestrial suppliers. High shipping cost/delay doesn't change that.
Oh, by no means did I mean to imply that dollars as an analytical tool should be discarded. Like, if I take it overly abstract and imagine some functional for "number of people supported" under constraints like "X set of minimal food per person" and "Y amount of pressurized volume per person" and so on, and maximize with respect to allocation of equipment and labor, that analysis would clearly produce lagrange multipliers giving you the marginal cost of this that and the other.

Such a functional would presumably be the output of a fairly specific plan, though. So my approach to the problem would be to start with a plan of what's being shipped and what's done with it, in order to work out the right order of magnitude for prices of things. If you pick $100/hr for labor and keep importing people until you fill all the things that would use labor if it really cost so little, you probably have too many people, and need to start your plan over with a higher labor rate.

Mars predictably will have price distortions, and I don't have a clear idea of which things and by how much. Because I don't even have a base case credible colony scheme in mind.

I agree it is pretty much impossible to estimate accurately when there are so many unknowns:
The degree of automation.
The transportation costs.
No comparables.
Distances and nature of local resources.
The size and function of the settlement as well as its growth rate.
The financial environment.
The available technologies.

However, there are a large number of propositions for colony development available, for example the 2019 Mars Society 1000 people colony contest received something like 100+ proposals.
My own proposal didn't make the cut, and was far away in the also rans, but still, I can refer it to you as a fairly typical one.  The design spreadsheets are under the 'Files' tab.
https://sites.google.com/view/estepona-on-mars
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/09/2020 06:11 pm
[Vertical vs horizontal]
my reason was that 1 mm stainless is floppy, so I didn't want it on its side until it was pressurized.

Note how SpaceX is holding the rings in place at they are welded to each other, even for vertical assembly. And, obviously, they are being held in a precise shape as they are manufactured. You need a welding frame anyway. The "floppiness" of the sheets doesn't affect this decision.

[Another issue that you've not covered is that pile on regolith after it's pressurised. This has been suggested before in the thread. It means that if there is an issue and the section is depressurised, it will crush under the regolith and be destroyed. At minimum, for basic safety, any structure should be able to support itself and any regolith load, while unpressurised.]

Building in place means you have to cart around all the module-building equipment. If you can build modules of low enough mass to cart those around instead, it may make sense to build the modules centrally.

OTOH, building horizontally means you can build continuously, you aren't limited to set lengths. Kind of like building a tunnel, or laying a rail line. Yes, your rig has to be mobile (although not very) but once you are set up, it only needs to work within the structure you've already built.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/09/2020 07:20 pm
[Vertical vs horizontal]
my reason was that 1 mm stainless is floppy, so I didn't want it on its side until it was pressurized.

Note how SpaceX is holding the rings in place at they are welded to each other, even for vertical assembly. And, obviously, they are being held in a precise shape as they are manufactured. You need a welding frame anyway. The "floppiness" of the sheets doesn't affect this decision.

That all sounds good in theory, but have you ever actually tried to work with a piece of material (especially a large piece) that's "fighting you" to get it lined up? Not fun.

[Another issue that you've not covered is that pile on regolith after it's pressurised. This has been suggested before in the thread. It means that if there is an issue and the section is depressurised, it will crush under the regolith and be destroyed. At minimum, for basic safety, any structure should be able to support itself and any regolith load, while unpressurised.]

You've tried enforcing this "rule" here many times, but in fact this is nothing more than your personal opinion.

Imo you're much better off simply making reliable buildings that don't depressurize. This whole things reminds me of nothing so much as a Victorian gentleman insisting that skyscrapers must be equipped with parachutes, rather than simply engineering safe, reliable skyscrapers.

I take the same approach to this as Elon takes to Starship LAS. If we can't make reliable, well-engineered habs that don't depressurize every week (or for that matter, every decade), Mars settlement is doomed anyway. For future Mars settlers, the idea of a hab depressurization will be as remote as a skyscraper falling down. Does it happen? Yes. Is it rare? Exceedingly.

Note that I'm not saying that no buildings will be constructed to hold up their rad shield when depressurized. On the contrary I think this will be common, especially for large buildings that hold expensive stuff. But I don't think that all Mars buildings must necessarily be built this way.

Building in place means you have to cart around all the module-building equipment. If you can build modules of low enough mass to cart those around instead, it may make sense to build the modules centrally.

OTOH, building horizontally means you can build continuously, you aren't limited to set lengths. Kind of like building a tunnel, or laying a rail line. Yes, your rig has to be mobile (although not very) but once you are set up, it only needs to work within the structure you've already built.

We have this already: it's called modern pre-fab composite steel buildings (see: pretty much any large commercial building). And they typically use bolted (not welded) connections, because in-the-field welding is more costly and easier to mess up / harder to inspect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 02/09/2020 07:21 pm
..
..
..
However, there are a large number of propositions for colony development available, for example the 2019 Mars Society 1000 people colony contest received something like 100+ proposals.
My own proposal didn't make the cut, and was far away in the also rans, but still, I can refer it to you as a fairly typical one.  The design spreadsheets are under the 'Files' tab.
https://sites.google.com/view/estepona-on-mars

Michel, Estepona looks really cool and well thought out. I just sent you a PM :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/09/2020 08:19 pm
[Another issue that you've not covered is that pile on regolith after it's pressurised. This has been suggested before in the thread. It means that if there is an issue and the section is depressurised, it will crush under the regolith and be destroyed. At minimum, for basic safety, any structure should be able to support itself and any regolith load, while unpressurised.]
You've tried enforcing this "rule" here many times

I think you've confused me with others. The only reason I mention it is because it has been raised by many people in this thread before.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/09/2020 09:37 pm
Did anybody read this book? Reviews?

https://www.amazon.com/Mars-Colonies-Plans-Settling-Planet/dp/097414438X
(Only reviewer so far, a guy called R. Zubrin, gives it five stars....)

https://twitter.com/robert_zubrin/status/1225876236477620225
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/09/2020 10:11 pm
Did anybody read this book? Reviews?

https://www.amazon.com/Mars-Colonies-Plans-Settling-Planet/dp/097414438X
(Only reviewer so far, a guy called R. Zubrin, gives it five stars....)

https://twitter.com/robert_zubrin/status/1225876236477620225
You can see most of the proposals on the Mars Society Youtube channel.  I've read a few of the proposals, and participated (modestly) in the preparation of one of them:  https://macroinvent.com/mars-1000/ by Kent Nebergall.  As mentioned above, my own didn't make the cut :-)  The winning proposal had at least one participant who is a regular here ;-).  There is an excellent proposal by the members of the French Mars Society, that are always interesting and rigorous in their work (Richard Heidmann). 
If you look on the Mars Society website you can find the winners and some images.
So it is basically a collection of 20 page papers detailing a 1000 people settlement.  I'll be buying it soon.

 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 02/12/2020 01:07 pm
https://www.marssociety.org/news/2020/02/11/mars-city-state-design-competition-announced/

Once more unto the Breach chums!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/12/2020 01:14 pm
https://www.marssociety.org/news/2020/02/11/mars-city-state-design-competition-announced/

Once more unto the Breach chums!


20 points aesthetic, huh? Well, make it look something like Alba City from Carole & Tuesday I guess...

...except for the slums on the outskirts of town.

Oh yeah, and pressurised.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/12/2020 05:40 pm
Thx for the info lamontagne.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/18/2020 04:32 pm
20 points aesthetic, huh? Well, make it look something like Alba City from Carole & Tuesday I guess...

...except for the slums on the outskirts of town.

Do we have a plan for achieving this goal of... eliminating poverty?

I doubt moving to Mars will lead to "the perfection of human nature," just like Communism didn't. So unless you're throwing people out airlocks, there will be poverty, and you'll need some affordable housing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 02/18/2020 06:18 pm
20 points aesthetic, huh? Well, make it look something like Alba City from Carole & Tuesday I guess...

...except for the slums on the outskirts of town.

Do we have a plan for achieving this goal of... eliminating poverty?

I doubt moving to Mars will lead to "the perfection of human nature," just like Communism didn't. So unless you're throwing people out airlocks, there will be poverty, and you'll need some affordable housing.
I'd expect a junkyard next to the spaceport, for stainless steel scrap that hasn't been used for something yet, while the raptors have already been shipped back to earth.

Cybertrucks with suitlocks for doors (and a footrailing so the suit legs don't drag while you drive)

The fuel plant with an ice receiving yard, big tanks, near the spaceport

A strip mine on a nearby escarpment, with an ISRU multi-refinery

A research district, with lots of variously equipped rovers of different nationalities.

A hydroponics sector, and of course miles upon miles of solar farm

Starport Transient housing, after you get off a ship but before you get a job, or after you get fired for being a dick but before you get a new job or fly home.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lumina on 05/23/2020 06:34 am
20 points aesthetic, huh? Well, make it look something like Alba City from Carole & Tuesday I guess...

...except for the slums on the outskirts of town.

Do we have a plan for achieving this goal of... eliminating poverty?

I doubt moving to Mars will lead to "the perfection of human nature," just like Communism didn't. So unless you're throwing people out airlocks, there will be poverty, and you'll need some affordable housing.

I'm not so sure there will be poverty on Mars for a very long time... survival and growth on Mars will depend on machines, and building & maintaining machines will at least partly depend on labour. So I think Mars may well turn out to be a full employment economy for decades to come.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/23/2020 12:01 pm
20 points aesthetic, huh? Well, make it look something like Alba City from Carole & Tuesday I guess...

...except for the slums on the outskirts of town.

Do we have a plan for achieving this goal of... eliminating poverty?

I doubt moving to Mars will lead to "the perfection of human nature," just like Communism didn't. So unless you're throwing people out airlocks, there will be poverty, and you'll need some affordable housing.

I'm not so sure there will be poverty on Mars for a very long time... survival and growth on Mars will depend on machines, and building & maintaining machines will at least partly depend on labour. So I think Mars may well turn out to be a full employment economy for decades to come.

Honestly, this was just a snarky quip about one the anime's shaky world-building. I have my own thoughts about how poverty would manifest (Total Recall as an example), but let's not derail this thread which is about habitats; there's plenty others about a potential SpaceX colony's society.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 05/25/2020 06:30 pm
20 points aesthetic, huh? Well, make it look something like Alba City from Carole & Tuesday I guess...

...except for the slums on the outskirts of town.

Do we have a plan for achieving this goal of... eliminating poverty?

I doubt moving to Mars will lead to "the perfection of human nature," just like Communism didn't. So unless you're throwing people out airlocks, there will be poverty, and you'll need some affordable housing.

I'm not so sure there will be poverty on Mars for a very long time... survival and growth on Mars will depend on machines, and building & maintaining machines will at least partly depend on labour. So I think Mars may well turn out to be a full employment economy for decades to come.

Honestly, this was just a snarky quip about one the anime's shaky world-building. I have my own thoughts about how poverty would manifest (Total Recall as an example), but let's not derail this thread which is about habitats; there's plenty others about a potential SpaceX colony's society.
Well in Mars someone has to provide the pressurised volume, and even the air you breathe!  One argument is that SpaceX brought person X here, SpaceX remains responsible.....  But returning more to the main topic here.... Quality of housing and the whole habitat experience has a big effect on Mental health. So making sure its not too depressing.... even where the roughest workers bunk, eat and have their rec time, must not be ignored! General causes of homelessness may seem off topic, but "Amazing Martian Habitats" should promote bright positive mental/emotional health!!!!!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/25/2020 10:25 pm
For the 1 000 000 people future, I've been thinking about providing something more interesting the the tunnels, so here is a kind of very large scale tube, in which robust construction provides radiation shielding of a varying degree depending on where you stand in the building.

The idea is that the design is a descendant of the use of 9 and 18m starships as habitats.  In a formal sense, the pressure part of the structure has been separated from the habitat part, These tubes can be combined in various ways.  The architecture is pretty much independant from the enveloppe.

The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure.  I would expect Mars to work out higher strength glass than what we have today, since we are still at about 1:100th of the maximum theoretical strength of glass, so the individual panes could be fairly large.  Been fiddling with Twinmotion for renderings; pretty cool renderings of plants and people
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/25/2020 10:31 pm
The envelope would be the pubic space, the interior buildings the private space.  All the underground areas would be for light industrial production, transportation and food production in grow rooms and vats.  Probably various type of storage as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/26/2020 01:10 am
The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure.

Then you'll need more than "ribbons" of stainless steel. Air pressure works in all directions, so the glass would need to hold the tension in the unreinforced axis. Instead it needs to be some kind of mesh (or, as Elon suggests, geodesic domes).

In any event, the glass will always be under strain anyway, specifically bending strain from the air pressure pushing the pane out. The glass is supported by the perimeter, but the force is across the entire area area. Or for a convex panel ("bubble"), the glass might be in pure tension. But there's no scenario where the glass takes zero strain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ludus on 05/26/2020 02:16 am
This is a tiered crater on Arcadia Planitia, at the scale of 300 or 400m across. The tiering is the unusual feature for Mars that lead to other investigation that concluded the plain had a 40m or 50m deep layer of water ice starting just below the surface.

Arcadia is a likely landing target having all this water and decently low latitude for sunlight.

The habitat structure this place suggests to me is a system of using ice mining in the plain to excavate pits that are at least as deep as the Bottom of the ice layer - so down to at least as far as the crater’s first tier and maybe into the regolith to the second tier.

The settlers are going to do this constantly and persistently anyway to get water for ISRU so why not take advantage of it? If it’s done in planned ways it might be a bit like  https://en.wikipedia.org/wiki/Room_and_pillar_mining (https://en.wikipedia.org/wiki/Room_and_pillar_mining) being used to create living space.

They’d excavate pits in controlled shapes. The excess regolith could be used to build walls for the pit over the ice layer. Pits would be at least 40 or 50m deep and probably several hundred across. The pit would then be covered by a roof that’s topped off with excess regolith. As has been discussed in great detail in this thread, the big issue with domes on Mars is anchoring them. In this case the roof is designed as air supported and held down by an appropriate mass of regolith. The roof would include light pipes to take in natural sunlight which might be reflected by mirrors on the plain to concentrate it. It would also have LEDs to supplement an artificial sky. Each room is about as big as a domed stadium.

There’s plenty of water available so hopefully the layout of a completed room would soon include a lot of pools and water features. Other rooms might be used as reservoirs.

These rooms would be pretty spacious, rather like large domes, but well shielded from the environment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/26/2020 02:58 am
The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure.
Then you'll need more than "ribbons" of stainless steel. [...] Instead it needs to be some kind of mesh

If you look at left side of the external shot, you can see the "domes" also have a mesh in the glass section, not just those wide steel arches. It doesn't seem to get rendered in the more distant or internal views.

[edit: Added crop of the image I meant.]

The glass is supported by the perimeter, but the force is across the entire area area.

Shorter the width of each pane, less force across that width, less force on the perimeter. As long force passing into the frame isn't transmitted back through other panes, but through the frame, the overall force isn't "felt" by the glass.

(That said, it looks like the glass panels are triangular. That's probably a particularly bad shape for glass under pressure.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/26/2020 03:02 am
The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure.

Then you'll need more than "ribbons" of stainless steel. Air pressure works in all directions, so the glass would need to hold the tension in the unreinforced axis. Instead it needs to be some kind of mesh (or, as Elon suggests, geodesic domes).

In any event, the glass will always be under strain anyway, specifically bending strain from the air pressure pushing the pane out. The glass is supported by the perimeter, but the force is across the entire area area. Or for a convex panel ("bubble"), the glass might be in pure tension. But there's no scenario where the glass takes zero strain.
Detailed mesh in first image.  The other 2 were simplified for fast rendering :-) the strain in the glass is transferred to the stainless.  All hoop stresses are in the metal, the glass is in flexion under an hyperstatic load case.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/26/2020 03:40 am
The roof would include light pipes to take in natural sunlight which might be reflected by mirrors on the plain to concentrate it.

Most of the hab volume will be agriculture (and associate systems), and most of the light required inside the habs will be for growing. Light-pipes and especially mirror-concentrators will work poorly on Mars due to the dust in the air. Even under "clear" conditions, you're only getting ~60% direct sunlight (and total sunlight is already half of Earth's, so 30% overall) falling off rapidly as dust levels increase.

And, even outside of storm years, roughly half a Mars year (around a full Earth year) has dusty skies where direct sunlight is <20%. Adding more mirrors to make up for those bad months creates self-shadowing issues, or requires extra construction of solar-towers to give line-of-sight. But then it's wasted for the rest of the year when you don't need the added capacity, because there's not much else you can do with it. Adding solar-thermal-industrial applications is possible, but adds complexity to the system, which invariably adds cost/maintenance issues.

On paper, sunlight-to-PV-to-LED seems lower-efficiency than sunlight+mirrors, but solar PV is more tolerant of higher dust levels. And if you add more panels to cope with expected low light periods, electricity is highly mutable, easily moved between application, so you can trade vehicle/industrial/agricultural demand against availability and urgency.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 05/26/2020 05:25 am
...here is a kind of very large scale tube...

The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure...

Hoop Stress

Just to give a starting number: 

A tube sitting on the martian surface, 40 m in diameter, with 1 cm walls and 0.6 atm, has hoop stress (https://www.engineersedge.com/calculators/hoop-stress.htm) of 120 MPa -- likely excessive, just as a start.

Hoop stress is proportional to diameter.  Diameter limit depends on all the stress factors, but for comparison: 

The ambitious, windowless, 1 atm habitat tube concept of Kennedy 1992 is restricted to a diameter of 8 m.  It aims to give living and working environment for a crew of 12.

Image:  Kennedy 1992, Fig. 7.  "Construction and assembly storyboard"

Refs.

Kennedy, K.J., 1992. A horizontal inflatable habitat for SEI. (https://www.researchgate.net/profile/Kriss_Kennedy/publication/23583224_Horizontal_inflatable_habitat_for_SEI/links/570b9e4708ae8883a1ffcf03/Horizontal-inflatable-habitat-for-SEI.pdf) Space, 92, pp.135-146.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/26/2020 08:26 am
...here is a kind of very large scale tube...

The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure...

Hoop Stress

Just to give a starting number: 

A tube sitting on the martian surface, 40 m in diameter, with 1 cm walls and 0.6 atm, has hoop stress (https://www.engineersedge.com/calculators/hoop-stress.htm) of 120 MPa -- likely excessive, just as a start.

Hoop stress is proportional to diameter.  Diameter limit depends on all the stress factors, but for comparison: 

The ambitious, windowless, 1 atm habitat tube concept of Kennedy 1992 is restricted to a diameter of 8 m.  It aims to give living and working environment for a crew of 12.

Image:  Kennedy 1992, Fig. 7.  "Construction and assembly storyboard"

Refs.

Kennedy, K.J., 1992. A horizontal inflatable habitat for SEI. (https://www.researchgate.net/profile/Kriss_Kennedy/publication/23583224_Horizontal_inflatable_habitat_for_SEI/links/570b9e4708ae8883a1ffcf03/Horizontal-inflatable-habitat-for-SEI.pdf) Space, 92, pp.135-146.

The paper you quote is for an inflatable habitat. Not a solid habitat. Inflatables use a Kevlar netting to carry loads away from the pressure bladder, letting the gaps in between "pillow" outwards. The revised Mars Ice House is a transparent inflatable concept exploiting this to enable a transparent habitat. This was discussed in length many, many posts back.

I would suggest that the glass cells be formed as pillowed in a similar manner, and that the steel banding between them being thicker. Although personally I would prefer acrylic for windows. Glass can be a treacherous beast.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/26/2020 12:09 pm
The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure.
Then you'll need more than "ribbons" of stainless steel. [...] Instead it needs to be some kind of mesh

If you look at left side of the external shot, you can see the "domes" also have a mesh in the glass section, not just those wide steel arches. It doesn't seem to get rendered in the more distant or internal views.

[edit: Added crop of the image I meant.]

The glass is supported by the perimeter, but the force is across the entire area area.

Shorter the width of each pane, less force across that width, less force on the perimeter. As long force passing into the frame isn't transmitted back through other panes, but through the frame, the overall force isn't "felt" by the glass.

(That said, it looks like the glass panels are triangular. That's probably a particularly bad shape for glass under pressure.)
It's a modeling limitation.  Creating angled hoops is horribly complex in Sketchup.  The bands would probably be angled at the propper hoop stress angle, 57 degrees, from memory.  The one used for banding COPV tanks.  That would give fairly rectangular windows.  That being said, as the window support is continuous and hyperstatic, i.e. needs to be solved by finite element analysis (there are equations but they hardly seem worth it) I haven't spent to much energy on it, the obvious ideal shape would be circle, but again a pain to model and gives a disco effect.  In my defence I would refer to the LEM windows, that were triangular.  A small reference, I admit :-)  The windows are only over a quarter of the diameter, with 50% of that area banded stainless.  So the actual glassed surface is about 12%.  The stainless steel used is planned for 400 MPa, and the glass would be quite strong as well.  This is a 'little' in the future, after all :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/26/2020 12:18 pm
...here is a kind of very large scale tube...

The glass is subdivided into smaller panes, all the strain is taken up by the stainless steel structure...

Hoop Stress

Just to give a starting number: 

A tube sitting on the martian surface, 40 m in diameter, with 1 cm walls and 0.6 atm, has hoop stress (https://www.engineersedge.com/calculators/hoop-stress.htm) of 120 MPa -- likely excessive, just as a start.

Hoop stress is proportional to diameter.  Diameter limit depends on all the stress factors, but for comparison: 

The ambitious, windowless, 1 atm habitat tube concept of Kennedy 1992 is restricted to a diameter of 8 m.  It aims to give living and working environment for a crew of 12.

Image:  Kennedy 1992, Fig. 7.  "Construction and assembly storyboard"

Refs.

Kennedy, K.J., 1992. A horizontal inflatable habitat for SEI. (https://www.researchgate.net/profile/Kriss_Kennedy/publication/23583224_Horizontal_inflatable_habitat_for_SEI/links/570b9e4708ae8883a1ffcf03/Horizontal-inflatable-habitat-for-SEI.pdf) Space, 92, pp.135-146.

The paper you quote is for an inflatable habitat. Not a solid habitat. Inflatables use a Kevlar netting to carry loads away from the pressure bladder, letting the gaps in between "pillow" outwards. The revised Mars Ice House is a transparent inflatable concept exploiting this to enable a transparent habitat. This was discussed in length many, many posts back.

I would suggest that the glass cells be formed as pillowed in a similar manner, and that the steel banding between them being thicker. Although personally I would prefer acrylic for windows. Glass can be a treacherous beast.
I understand the Acrylic but I'm hoping to take advantage of the much lower embodied energy in glass.  My main worry at this point is the leaks at all those joints.  I expect glass would need to be improved a bit for this to be really possible, and I also expect the need to drive some research into stronger large scale glass for Mars.  I'm also counting on whatever is eventually developed for the Starship main window, which is, in the narrative, the ancestor of this arrangement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/26/2020 12:25 pm
The roof would include light pipes to take in natural sunlight which might be reflected by mirrors on the plain to concentrate it.

Most of the hab volume will be agriculture (and associate systems), and most of the light required inside the habs will be for growing. Light-pipes and especially mirror-concentrators will work poorly on Mars due to the dust in the air. Even under "clear" conditions, you're only getting ~60% direct sunlight (and total sunlight is already half of Earth's, so 30% overall) falling off rapidly as dust levels increase.

And, even outside of storm years, roughly half a Mars year (around a full Earth year) has dusty skies where direct sunlight is <20%. Adding more mirrors to make up for those bad months creates self-shadowing issues, or requires extra construction of solar-towers to give line-of-sight. But then it's wasted for the rest of the year when you don't need the added capacity, because there's not much else you can do with it. Adding solar-thermal-industrial applications is possible, but adds complexity to the system, which invariably adds cost/maintenance issues.

On paper, sunlight-to-PV-to-LED seems lower-efficiency than sunlight+mirrors, but solar PV is more tolerant of higher dust levels. And if you add more panels to cope with expected low light periods, electricity is highly mutable, easily moved between application, so you can trade vehicle/industrial/agricultural demand against availability and urgency.
Salles de croissance is french for grow rooms :-)  so that's the main use for all the underground space in the tube.  'Underground' areas also allows a fully walkable living area.  This works better in larger habitats, hence the 36-40m diameter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/26/2020 12:47 pm
As identified by 'others'  ;) stainless steel, or just plain steel, is quite strong and cheap, everything considered.  Separating the pressure vessel function from the habitat function seems to simplify design and reduce leaks.  The tube shape removes the ground and anchoring problems that domes have.  Using a probabilistic radiation dosage (high in glassed areas, low in sleeping quarters and work areas) makes the glass more acceptable.  Just stay 'indoors' during solar storms.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 05/26/2020 03:32 pm
I would prefer acrylic for windows.

Acrylic thermal expansion is ~ 6x that of steel.  Thermal stress would likely shatter acrylic overnight, even without the tube's excessive hoop stress above (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2086748#msg2086748), and other issues that disqualify acrylic specifically, below.  Any hab concept should check such things. 

I've never seen a plausible engineering sketch for a freestanding 40+ m hab tube, of any design.

Image:  Acrylic vacuum chamber.  Sanatron.

Quote from: sanatron.com
Disadvantages of using a Chamber made from Acrylic (https://www.sanatron.com/articles/clear-acrylic-vac-chamber-in-depth-review.php)

Acrylic is more permeable than metal
The first disadvantage of acrylic is its permeability and outgassing. Permeable materials diffuse air more quickly through the walls which means that an acrylic vacuum chamber will be at a persistent vacuum loss over time. Additionally, acrylic will outgas molecules from its wall at a rate that is 2 to 3 orders of magnitude higher than steel. This also prevents acrylic chambers from being the appropriate choice in high vacuum applications.

Acrylic operates in narrow temperature range
Acrylic has a melting point of 320 °F (160 °C) and a glass transition temperature of 221 °F (105 °C). This fact eliminates acrylic as a suitable material for high temperature applications. In fact, acrylic vacuum chambers should not be heated beyond 105 °F (40 °C). Likewise acrylic becomes incredibly brittle at temperatures below -112°F (-80 °C), disqualifying it for cryogenic vacuum applications.

Chemically Susceptible
Acrylic is not chemically resistant to some materials used in labs such as Alcohols, Acetones, Hydrogen Peroxide, Thinners, Benzenes, Lactates, and other. This means that constant exposure to these compounds will blemish, even damage the acrylic walls of the chamber.

Prone to electrostatic buildup
Acrylic Chambers may cause static electricity if "rubbed the wrong way", which may potentially damage electronics, ignite volatile gasses, or create electrostatic noise. Acrylic gets zero shielding from electromagnetic interference but that may only pose a problem if there are strong electric fields in the vicinity.

Acrylic is strong but brittle
Another disadvantage of acrylic chambers is that acrylic is brittle and it will crack under concentrated stresses. This means that it is not recommended to thread acrylic because the force put onto the acrylic from the screw threads will develop cracks and crazes in the acrylic material. Finally, due to its material properties, acrylic vacuum chambers require thick walls even at small vacuum volumes in order to withstand the stress of ambient atmospheric pressure. This results in an exponential wall thickness requirement as the vacuum chamber volume increases; hence, acrylic vacuum chambers may not be ideal materials in large vacuum applications.

Acrylic can be scratched easily
The walls of the acrylic vacuum chamber can be scratched easily with a sharp or coarse object. Even dragging the chamber across the floor will create visible scratches on the bottom wall. Depending on the depth of the scratch, these may not be easily reparable. Though not something that would compromise the structural integrity of the chamber, these scratches can become a cosmetic nuisance.

To summarize, the disadvantages of using Acrylic Vacuum Chambers are:

- Low Vacuum (Permeability and Outgassing) - Acrylic chambers consistently lose vacuum due to the fact that air traverses through its walls. In addition to permeability, acrylic walls outgas at much higher rate than aluminum or steel.
- Room Temperature Only - Acrylic is not suitable for high temperature vacuum applications nor is it suitable for low temperature applications.
- Chemical Resistance - Acrylic may be damaged by common laboratory chemicals such as alcohols, acetones, thinners, etc.
- Static Accumulating - may cause electrostatic discharge causing electronic equipment damage.
- Brittle - Cracks under concentrated stresses.
- Thick Walls - May not be suitable for large sized chambers.
- Easily Scratched – Acrylic walls can be easily scratched with a sharp or coarse object.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/26/2020 03:46 pm
I would prefer acrylic for windows.

Acrylic thermal expansion is ~ 6x that of steel.  Thermal stress would likely shatter acrylic overnight, even without the tube's excessive hoop stress above (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2086748#msg2086748), and other issues that disqualify acrylic specifically, below.  Any hab concept should check such things. 

I've never seen a plausible engineering sketch for a 40+ m hab tube, of any design.

Image:  Acrylic vacuum chamber.  Sanatron.

Quote from: sanatron.com
Disadvantages of using a Chamber made from Acrylic (https://www.sanatron.com/articles/clear-acrylic-vac-chamber-in-depth-review.php)

Acrylic is more permeable than metal
The first disadvantage of acrylic is its permeability and outgassing. Permeable materials diffuse air more quickly through the walls which means that an acrylic vacuum chamber will be at a persistent vacuum loss over time. Additionally, acrylic will outgas molecules from its wall at a rate that is 2 to 3 orders of magnitude higher than steel. This also prevents acrylic chambers from being the appropriate choice in high vacuum applications.

Acrylic operates in narrow temperature range
Acrylic has a melting point of 320 °F (160 °C) and a glass transition temperature of 221 °F (105 °C). This fact eliminates acrylic as a suitable material for high temperature applications. In fact, acrylic vacuum chambers should not be heated beyond 105 °F (40 °C). Likewise acrylic becomes incredibly brittle at temperatures below -112°F (-80 °C), disqualifying it for cryogenic vacuum applications.

Chemically Susceptible
Acrylic is not chemically resistant to some materials used in labs such as Alcohols, Acetones, Hydrogen Peroxide, Thinners, Benzenes, Lactates, and other. This means that constant exposure to these compounds will blemish, even damage the acrylic walls of the chamber.

Prone to electrostatic buildup
Acrylic Chambers may cause static electricity if "rubbed the wrong way", which may potentially damage electronics, ignite volatile gasses, or create electrostatic noise. Acrylic gets zero shielding from electromagnetic interference but that may only pose a problem if there are strong electric fields in the vicinity.

Acrylic is strong but brittle
Another disadvantage of acrylic chambers is that acrylic is brittle and it will crack under concentrated stresses. This means that it is not recommended to thread acrylic because the force put onto the acrylic from the screw threads will develop cracks and crazes in the acrylic material. Finally, due to its material properties, acrylic vacuum chambers require thick walls even at small vacuum volumes in order to withstand the stress of ambient atmospheric pressure. This results in an exponential wall thickness requirement as the vacuum chamber volume increases; hence, acrylic vacuum chambers may not be ideal materials in large vacuum applications.

Acrylic can be scratched easily
The walls of the acrylic vacuum chamber can be scratched easily with a sharp or coarse object. Even dragging the chamber across the floor will create visible scratches on the bottom wall. Depending on the depth of the scratch, these may not be easily reparable. Though not something that would compromise the structural integrity of the chamber, these scratches can become a cosmetic nuisance.

To summarize, the disadvantages of using Acrylic Vacuum Chambers are:

- Low Vacuum (Permeability and Outgassing) - Acrylic Chambers consistently loose vacuum due to the fact that air traverses through its walls. In addition to permeability, acrylic walls outgas at much higher rate than aluminum or steel.
- Room Temperature Only - Acrylic is not suitable for high temperature vacuum applications nor is it suitable for low temperature applications.
- Chemical Resistance - Acrylic may be damaged by common laboratory chemicals such as alcohols, acetones, thinners, etc.
- Static Accumulating - may cause electrostatic discharge causing electronIC equipment damage.
- Brittle - Cracks under Concentrated Stresses.
- Thick Walls - May not be suitable for large sized chambers.
- Easily Scratched – Acrylic Walls can be easily scratched with a sharp or coarse object.
Well, time to set to work and explain why the 40m tube illustrated will never work :-).  Admittedly a little in the future.
Start with 9m tubes, i.e Starship on the side.  Move to 18m tubes, Starship 2 (presuming it is cylindrical with a constant diameter). If it can fly to Mars, it can side on the side for a few decades, I expect.  Then moving on to purpose built 36 (or 40)m tubes with in situ resources.  Not starting with 40m tubes of course, that would be silly.  Of course a fair argument is that who knows what will be available in a few decades, and I can't answer to that!  I'm actually more interested in glass than acrylic.  https://en.wikipedia.org/wiki/Strength_of_glass.  There is plenty of space for improvement from 7 MPa to 17 GPa!!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 05/26/2020 04:08 pm
I'd just like to point out that there is a (relatively) straight path from Martian Water and Atmosphere to ethylene-vinyl acetate, a component of Laminated 'Shatterproof' glass.

And with acid treatment, glass itself can be VERY strong. Plenty of ways to make acids out of Martian Soil.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/26/2020 05:36 pm
I'd just like to point out that there is a (relatively) straight path from Martian Water and Atmosphere to ethylene-vinyl acetate, a component of Laminated 'Shatterproof' glass.

And with acid treatment, glass itself can be VERY strong. Plenty of ways to make acids out of Martian Soil.
I think it very likely that the 'glass' used for habitats will be some kind of laminate; ethyl vinyle acetate might be a great candidate for one of the layers, as glass will probably always be subject to stress concentration failure (A certain test made on a Tesla prototype comes to mind  :-)
I expect there will also be a thermal film, opaque to infrared but transparent to sunlight.  And there probably is a double pane design for insulation, with the inner pane providing pressure resistance and the outer pane scratch protection and a gap to reduce convection loads. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 06/12/2020 07:24 am
I like acrylic because it's widely used in aerospace, low thermal conductivity, very transmissive (good for dim Mars), lighter than glass, has a high hydrogen content for radiation protection and uses the elements involved in propellant production. You can seamlessly weld large pieces together with chemicals (like those giant cylindrical aquariums). On the downside, it's not as energy efficient to manufacture per kg as glass is, perhaps offset by the gains in its insulation properties, lower mass requirements etc.

I would prefer acrylic for windows.

Acrylic thermal expansion is ~ 6x that of steel.  Thermal stress would likely shatter acrylic overnight, even without the tube's excessive hoop stress above (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2086748#msg2086748), and other issues that disqualify acrylic specifically, below.  Any hab concept should check such things. 
...

Acrylic pressure panes are space-proven. Spacecraft and habitat windows are mounted with gaskets, and have redundant panes. Aircraft panes are either clamped in or bolted in: I expect the choice will be clamping since they're not expected to take loads like an airframe does, just pressure and self-weight. Easier to replace as well.

Probably two pressure panes and an outer and inner pane, as with spacecraft. Maybe with a film heating system to regulate temps.

I'd just like to point out that there is a (relatively) straight path from Martian Water and Atmosphere to ethylene-vinyl acetate, a component of Laminated 'Shatterproof' glass.

And with acid treatment, glass itself can be VERY strong. Plenty of ways to make acids out of Martian Soil.

This is an interesting option for glass, thank you for pointing that out! Glass can also be heat-tempered for strength.

The AquaDom in Berlin is a nice example of a structure we can draw inspiration from for a Martian "outdoor experience structure".

By Vxla at English Wikipedia, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=29133896
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/02/2020 07:52 am
Sooooo did anyone else here put in for the Mars Society's latest design competition?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/02/2020 09:08 am
Sooooo did anyone else here put in for the Mars Society's latest design competition?

Nope. Just been playing a lot of Surviving Mars and Offworld Trading Company :P
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/02/2020 12:40 pm
Sooooo did anyone else here put in for the Mars Society's latest design competition?
Yes, I got together with a team from France and we've managed to send it our project:  Foundation, Mars City State.  There are a few images earlier in this thread.  Anyone else?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/02/2020 03:08 pm
Well you probably guessed my team (Southern Cross Innovations....or the Team formerly known as Team Spaceship) put in a design.

We found a way to scale up our previous design, based on steel silos.

Though now they are more the size of steel colosseums.
Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.


EDIT:
Behold! The Martian Colosseum!

Scaled up from our previous design, the Martian Silo, it is made out of nearly 2,000 tonne of steel, with 20 meter thick concrete/brick/earth work walls on the ourside to provide anchorage, radiation sheilding, and physical protection. These walls are also used for apartments on the inside, and storage arches on the outside (and yes I did the maths, this is enough to anchore the dome). The steel walls are 20 meters high and made of 24mm thick steel plate that at the internal pressure (50 kPa and 30% oxygen) sees a stress of 160 MPa, well below both yeild and fatigue stress.

The steel walls exist inside a 3m gap between the inner and outer wall with verticle stringers to provide strength and support, as well as access for maintenance. Corrosion protection comes from sacrifical anodes made of either aluminium or magnesium.

The Side walls support a second level, which is covered in a 30 meter high dome, allowing for roughly 20,106.19m2 of open communal space (here being used for a pedestrian boulevard through a vineyard and winery...oooh!). The floor is rated to carry a load of moist soil, 2 meters thick, allowing for further radiation protection.

Inside the colosseum, there is a pit 14 meters deep, dominated by a cental, circular apartment block, with the outer wall being used for underground pedestrican access ways, or light industry in man-made caves. The foundations of the apartments also contain spaces for offices, small buisness, bars and general recreational spots. In total, 950 people can live in one of these when configured like this, each with a 45m2 apartment. The Apartments also help suppor the Second Floor, and also contain life support and air conditioning units at the top, which are servies by people drafted from the populations, think jury duty but if you don't do it you all die (training is included). Finally, in the center of the Apartment blocks is a station leading down to a second layer of tunnels, housing a track-less tram system allowing for rapid transit throught he city (note, not all colosseums have a station, more like 1 in 20)

You would need aproximately 1,050 to house a population of 1 million people. If the steel used is solely sourced from the Martian soil, this would require the excavation of a pit ~ 8 km x 8 km, but only 1 meter deep. Big, but given the costs/limits of moving to Mars, it is unlikely that you would have to do this in less than 50 years, 40 years minimum. Such a production rate and size would be nothing compared to even a small steel mine on Earth.

Title: Re: Envisioning Amazing Martian Habitats
Post by: wes_wilson on 07/03/2020 12:20 am
Well you probably guessed my team (Southern Cross Innovations....or the Team formerly known as Team Spaceship) put in a design.

We found a way to scale up our previous design, based on steel silos.

Though now they are more the size of steel colosseums.
Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.


EDIT:
Behold! The Martian Colosseum!

Scaled up from our previous design, the Martian Silo, it is made out of nearly 2,000 tonne of steel, with 20 meter thick concrete/brick/earth work walls on the ourside to provide anchorage, radiation sheilding, and physical protection. These walls are also used for apartments on the inside, and storage arches on the outside (and yes I did the maths, this is enough to anchore the dome). The steel walls are 20 meters high and made of 24mm thick steel plate that at the internal pressure (50 kPa and 30% oxygen) sees a stress of 160 MPa, well below both yeild and fatigue stress.

The steel walls exist inside a 3m gap between the inner and outer wall with verticle stringers to provide strength and support, as well as access for maintenance. Corrosion protection comes from sacrifical anodes made of either aluminium or magnesium.

The Side walls support a second level, which is covered in a 30 meter high dome, allowing for roughly 20,106.19m2 of open communal space (here being used for a pedestrian boulevard through a vineyard and winery...oooh!). The floor is rated to carry a load of moist soil, 2 meters thick, allowing for further radiation protection.

Inside the colosseum, there is a pit 14 meters deep, dominated by a cental, circular apartment block, with the outer wall being used for underground pedestrican access ways, or light industry in man-made caves. The foundations of the apartments also contain spaces for offices, small buisness, bars and general recreational spots. In total, 950 people can live in one of these when configured like this, each with a 45m2 apartment. The Apartments also help suppor the Second Floor, and also contain life support and air conditioning units at the top, which are servies by people drafted from the populations, think jury duty but if you don't do it you all die (training is included). Finally, in the center of the Apartment blocks is a station leading down to a second layer of tunnels, housing a track-less tram system allowing for rapid transit throught he city (note, not all colosseums have a station, more like 1 in 20)

You would need aproximately 1,050 to house a population of 1 million people. If the steel used is solely sourced from the Martian soil, this would require the excavation of a pit ~ 8 km x 8 km, but only 1 meter deep. Big, but given the costs/limits of moving to Mars, it is unlikely that you would have to do this in less than 50 years, 40 years minimum. Such a production rate and size would be nothing compared to even a small steel mine on Earth.

Very nice.  Next time you need a space lawyer, give me a shout.  =)  Am a lawyer and becoming a space lawyer sounds even better lol
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/03/2020 06:42 am
Well you probably guessed my team (Southern Cross Innovations....or the Team formerly known as Team Spaceship) put in a design.

We found a way to scale up our previous design, based on steel silos.

Though now they are more the size of steel colosseums.
Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.


EDIT:
Behold! The Martian Colosseum!

Scaled up from our previous design, the Martian Silo, it is made out of nearly 2,000 tonne of steel, with 20 meter thick concrete/brick/earth work walls on the ourside to provide anchorage, radiation sheilding, and physical protection. These walls are also used for apartments on the inside, and storage arches on the outside (and yes I did the maths, this is enough to anchore the dome). The steel walls are 20 meters high and made of 24mm thick steel plate that at the internal pressure (50 kPa and 30% oxygen) sees a stress of 160 MPa, well below both yeild and fatigue stress.

The steel walls exist inside a 3m gap between the inner and outer wall with verticle stringers to provide strength and support, as well as access for maintenance. Corrosion protection comes from sacrifical anodes made of either aluminium or magnesium.

The Side walls support a second level, which is covered in a 30 meter high dome, allowing for roughly 20,106.19m2 of open communal space (here being used for a pedestrian boulevard through a vineyard and winery...oooh!). The floor is rated to carry a load of moist soil, 2 meters thick, allowing for further radiation protection.

Inside the colosseum, there is a pit 14 meters deep, dominated by a cental, circular apartment block, with the outer wall being used for underground pedestrican access ways, or light industry in man-made caves. The foundations of the apartments also contain spaces for offices, small buisness, bars and general recreational spots. In total, 950 people can live in one of these when configured like this, each with a 45m2 apartment. The Apartments also help suppor the Second Floor, and also contain life support and air conditioning units at the top, which are servies by people drafted from the populations, think jury duty but if you don't do it you all die (training is included). Finally, in the center of the Apartment blocks is a station leading down to a second layer of tunnels, housing a track-less tram system allowing for rapid transit throught he city (note, not all colosseums have a station, more like 1 in 20)

You would need aproximately 1,050 to house a population of 1 million people. If the steel used is solely sourced from the Martian soil, this would require the excavation of a pit ~ 8 km x 8 km, but only 1 meter deep. Big, but given the costs/limits of moving to Mars, it is unlikely that you would have to do this in less than 50 years, 40 years minimum. Such a production rate and size would be nothing compared to even a small steel mine on Earth.

Very nice.  Next time you need a space lawyer, give me a shout.  =)  Am a lawyer and becoming a space lawyer sounds even better lol

Thanks! If anything happens to my current one, I'll hit you up :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 07/03/2020 08:34 am
I get a bit of a Pantheon vibe with the silo... - Ambitious plan!

https://youtu.be/Oj6YmdUoiiQ
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/03/2020 10:14 am
Well you probably guessed my team (Southern Cross Innovations....or the Team formerly known as Team Spaceship) put in a design.

We found a way to scale up our previous design, based on steel silos.

Though now they are more the size of steel colosseums.
Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.


EDIT:
Behold! The Martian Colosseum!
How does your floor work? You need about 27ton/m2 to force the floor flat. Im not sure what your entire surface area of your floor is, but if it averages less than that, the floor would bulge down and push the whole structure up.

Its not hard to fix, but once we worked out the forces, its hard to not think about it.

We also submitted a design, Nexus Aurora, but opted to have the whole city have natural light under a pool of water.

We had a lot of different structures though. This is just one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/03/2020 11:16 am
Well you probably guessed my team (Southern Cross Innovations....or the Team formerly known as Team Spaceship) put in a design.

We found a way to scale up our previous design, based on steel silos.

Though now they are more the size of steel colosseums.
Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.


EDIT:
Behold! The Martian Colosseum!
How does your floor work? You need about 27ton/m2 to force the floor flat. Im not sure what your entire surface area of your floor is, but if it averages less than that, the floor would bulge down and push the whole structure up.

Its not hard to fix, but once we worked out the forces, its hard to not think about it.

We also submitted a design, Nexus Aurora, but opted to have the whole city have natural light under a pool of water.

We had a lot of different structures though. This is just one.

The graphic is a bit simplified. Between the walls and the apartment block, and inside the aprtment block would have arched supports on the underside of the Second Floor. But fundamentally, the gap between the main area and the second floor isn't sealed.

It's one big pressure vessel, not two.

Maybe not the best idea from a safety perspective, but, it could be solved with some minor modifications, with the central park essentially taking the form of a small hill.

We decided on a (relatively) standardised habitat structure that could then be customised as necessary, so that instead of having to have complicated robotics or 3D print everything, we minimised labour via production line assembly. The only place that would really need 'surface labour' is the construction of the steel walls and the dome, with the inner and outer walls being built with automatic brick layers (see Fast Brick Robotics). The pit would be made first, of course, then the foundations would be layed. Inner wall build automaticslly, then steel wall and dome constructed by welding together prefabiracted sections. Onces thats done, pressurise and constructe what ever you need inside as necessary!

I've got to admit, very jealous of the lovely graphics, they look amazing!
Unfortunately my main skills are in FEMAP, so I could do a wonderful structural analysis! but it would essentially be a funky shaped rainbow.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/03/2020 11:27 am
I get a bit of a Pantheon vibe with the silo... - Ambitious pan!

https://youtu.be/Oj6YmdUoiiQ

That was the idea, can also be made to give Hagia Sophia vibes as well!
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/03/2020 12:15 pm

The graphic is a bit simplified. Between the walls and the apartment block, and inside the aprtment block would have arched supports on the underside of the Second Floor. But fundamentally, the gap between the main area and the second floor isn't sealed.

It's one big pressure vessel, not two.

Maybe not the best idea from a safety perspective, but, it could be solved with some minor modifications, with the central park essentially taking the form of a small hill.

We decided on a (relatively) standardised habitat structure that could then be customised as necessary, so that instead of having to have complicated robotics or 3D print everything, we minimised labour via production line assembly. The only place that would really need 'surface labour' is the construction of the steel walls and the dome, with the inner and outer walls being built with automatic brick layers (see Fast Brick Robotics). The pit would be made first, of course, then the foundations would be layed. Inner wall build automaticslly, then steel wall and dome constructed by welding together prefabiracted sections. Onces thats done, pressurise and constructe what ever you need inside as necessary!

I've got to admit, very jealous of the lovely graphics, they look amazing!
Unfortunately my main skills are in FEMAP, so I could do a wonderful structural analysis! but it would essentially be a funky shaped rainbow.
Its nice to see other submissions too.

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

And we had quite a few energetic people to make renders.

Below is a farm and school building proposal as well
Title: Re: Envisioning Amazing Martian Habitats
Post by: tbellman on 07/03/2020 01:06 pm
Behold! The Martian Colosseum!

Scaled up from our previous design, the Martian Silo, it is made out of nearly 2,000 tonne of steel, with 20 meter thick concrete/brick/earth work walls on the ourside to provide anchorage, radiation sheilding, and physical protection. These walls are also used for apartments on the inside, and storage arches on the outside (and yes I did the maths, this is enough to anchore the dome). The steel walls are 20 meters high and made of 24mm thick steel plate that at the internal pressure (50 kPa and 30% oxygen) sees a stress of 160 MPa, well below both yeild and fatigue stress.

To make sure I understand it correctly, those outer concrete/brick side walls are above ground, while both the pedestrian and the tram/utilities tunnels are below ground?  So ground level is at the red line I have drawn in the attached image?  Or is everything except the dome and the "boulevard" below ground?

The boulevard seems like it will extend beyond the outer side walls; will that then be a walkway on pillars (20 meters high) to the next colosseum?

Quote from: Rocket Surgeon
The steel walls exist inside a 3m gap between the inner and outer wall with verticle stringers to provide strength and support, as well as access for maintenance. Corrosion protection comes from sacrifical anodes made of either aluminium or magnesium.

That 3 meter gap is the grey vertical band in the middle of the side wall, right?  And your first image shows the steel wall as a dark line in the middle of that grey band.

Quote from: Rocket Surgeon
The Side walls support a second level, which is covered in a 30 meter high dome, allowing for roughly 20,106.19m2 of open communal space (here being used for a pedestrian boulevard through a vineyard and winery...oooh!). The floor is rated to carry a load of moist soil, 2 meters thick, allowing for further radiation protection.

The dome is then 160 meters in diameter, and the outermost maybe 5 meters are not very usable, as the dome gets too low.  The outer wall brick seems then to be 180 meters in diameter, and the central apartment block seems to be 100 meters in diameter.

(As a teetotaller, I'm not overly fond of the choice of a vineyard, and would much prefer a fruit tree orchard, a Japanese garden, or maybe a tea plantation. ;))


The two middle images, the ones named "Martian Silo" and "Silo - Cross Section", are those from your older design?  I was a bit confused first when I tried to mentally match them up with the first and last image, and your description.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/03/2020 01:35 pm

The graphic is a bit simplified. Between the walls and the apartment block, and inside the aprtment block would have arched supports on the underside of the Second Floor. But fundamentally, the gap between the main area and the second floor isn't sealed.

It's one big pressure vessel, not two.

Maybe not the best idea from a safety perspective, but, it could be solved with some minor modifications, with the central park essentially taking the form of a small hill.

We decided on a (relatively) standardised habitat structure that could then be customised as necessary, so that instead of having to have complicated robotics or 3D print everything, we minimised labour via production line assembly. The only place that would really need 'surface labour' is the construction of the steel walls and the dome, with the inner and outer walls being built with automatic brick layers (see Fast Brick Robotics). The pit would be made first, of course, then the foundations would be layed. Inner wall build automaticslly, then steel wall and dome constructed by welding together prefabiracted sections. Onces thats done, pressurise and constructe what ever you need inside as necessary!

I've got to admit, very jealous of the lovely graphics, they look amazing!
Unfortunately my main skills are in FEMAP, so I could do a wonderful structural analysis! but it would essentially be a funky shaped rainbow.
Its nice to see other submissions too.

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

And we had quite a few energetic people to make renders.

Below is a farm and school building proposal as well

Oh for sure, I think it really comes down to design philisophy and manufacturability, but there are going to be dozens of different habitate designs, use of local geographic features not withstanding.

We mainly went into indepth design of one as an example, thought of a few variants, then moved on to other parts of the design, e.g. production.

Speaking of which, did Nexus Aurora come up with any good resources/ideas on finding copper?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/03/2020 01:49 pm
Behold! The Martian Colosseum!

Scaled up from our previous design, the Martian Silo, it is made out of nearly 2,000 tonne of steel, with 20 meter thick concrete/brick/earth work walls on the ourside to provide anchorage, radiation sheilding, and physical protection. These walls are also used for apartments on the inside, and storage arches on the outside (and yes I did the maths, this is enough to anchore the dome). The steel walls are 20 meters high and made of 24mm thick steel plate that at the internal pressure (50 kPa and 30% oxygen) sees a stress of 160 MPa, well below both yeild and fatigue stress.

To make sure I understand it correctly, those outer concrete/brick side walls are above ground, while both the pedestrian and the tram/utilities tunnels are below ground?  So ground level is at the red line I have drawn in the attached image?  Or is everything except the dome and the "boulevard" below ground?

The boulevard seems like it will extend beyond the outer side walls; will that then be a walkway on pillars (20 meters high) to the next colosseum?

Quote from: Rocket Surgeon
The steel walls exist inside a 3m gap between the inner and outer wall with verticle stringers to provide strength and support, as well as access for maintenance. Corrosion protection comes from sacrifical anodes made of either aluminium or magnesium.

That 3 meter gap is the grey vertical band in the middle of the side wall, right?  And your first image shows the steel wall as a dark line in the middle of that grey band.

Quote from: Rocket Surgeon
The Side walls support a second level, which is covered in a 30 meter high dome, allowing for roughly 20,106.19m2 of open communal space (here being used for a pedestrian boulevard through a vineyard and winery...oooh!). The floor is rated to carry a load of moist soil, 2 meters thick, allowing for further radiation protection.

The dome is then 160 meters in diameter, and the outermost maybe 5 meters are not very usable, as the dome gets too low.  The outer wall brick seems then to be 180 meters in diameter, and the central apartment block seems to be 100 meters in diameter.

(As a teetotaller, I'm not overly fond of the choice of a vineyard, and would much prefer a fruit tree orchard, a Japanese garden, or maybe a tea plantation. ;))


The two middle images, the ones named "Martian Silo" and "Silo - Cross Section", are those from your older design?  I was a bit confused first when I tried to mentally match them up with the first and last image, and your description.

Yup, the red line is ground level, we decided to split the difference and build both up and dig down. The boulevards would need some supports to reach the next colosseum but a) not all of the colosseums would have the boulevards and b) they are going to be pretty tightly packed in order to make spacing and transport more efficent.

Yes the 3 meter gap is the grey section. What is shown there is one of the supports/stringers running up the side to reinforce the steel wall. Those supports are roughly every 30 degrees around the perimeter.

Dome is 160 meters in diameter with the inner wall ending 140 meters in diameter and the outer wall 180 meters in diameter.

Middle two images are our old design from our previous report, which you can find in the Mars Society book (we did 'The Engineering Requirements for a Large Martian Population and Their Implications'). Though those images aren't included.

Shame, I'm a massive wine fan, and am particularily interested to see what Martian soil and gravity does to the flavour. As an example the Malbec grape changed falvour when moved from Europe to Argentina due to the different soil and climate, which is now probably the only place to get a good Malbec wine from (in my opinion :P ). The beauty of exporting wine/whiskey back from Mars as a luxury good is that it doesn't even have to ACTUALLy taste good.... no one is going to say a $500 - $1000 bottle of wine tastes bad after dropping that much money on it! :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/03/2020 05:22 pm
A few views of one of the martian habitats of the Foundation City State.
Mostly showing the public space.  The inspiration comes from the Edinburgh New Town area, with a high density of habitation.  I just need to find how to turn on clipping in Twinmotion to show the lower levels :-)  The larger cylinders house about 250 people.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/03/2020 06:06 pm
Clipped!

Of the lower levels, the highest is transportation and storage, then grow rooms for food production and services areas at the bottom.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/03/2020 06:37 pm
Speaking of which, did Nexus Aurora come up with any good resources/ideas on finding copper?
Well, the problem is the remote sensing information is too low to make out where proper Cu would be.

So we opted for a landing site near a lot of basalt rock and other ancient volcanic activity. As well as a ancient river bed, this gave us a large variety of different geological sources that we could tap into. The millions of meteorite craters would also have been a obvious candidates to find rare minerals.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/03/2020 06:38 pm
A few views of one of the martian habitats of the Foundation City State.
Mostly showing the public space.  The inspiration comes from the Edinburgh New Town area, with a high density of habitation.  I just need to find how to turn on clipping in Twinmotion to show the lower levels :-)  The larger cylinders house about 250 people.
Wow, those are some really cool looking villas. Would have some nice views.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/03/2020 07:01 pm
[snip]

Behold! The Martian Colosseum!

Scaled up from our previous design, the Martian Silo, it is made out of nearly 2,000 tonne of steel, with 20 meter thick concrete/brick/earth work walls on the ourside to provide anchorage, radiation sheilding, and physical protection. These walls are also used for apartments on the inside, and storage arches on the outside (and yes I did the maths, this is enough to anchore the dome).

So despite the superficial appearance of a concrete wall supporting a dome, this should actually be understood structurally as a concrete ballast hanging from a pressure-supported dome, correct?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/03/2020 07:04 pm
A few views of a main street, a triple tube with central road and two rows of buildings.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/03/2020 07:07 pm
A few views of one of the martian habitats of the Foundation City State.
Mostly showing the public space.  The inspiration comes from the Edinburgh New Town area, with a high density of habitation.  I just need to find how to turn on clipping in Twinmotion to show the lower levels :-)  The larger cylinders house about 250 people.
Wow, those are some really cool looking villas. Would have some nice views.
Yes, in particular those on the central peak of Nicholson Crater, one of our settlement sites :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/03/2020 07:12 pm

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

Of those "hundreds of ways," which one was the cheapest?

You can assume I want to construct a factory or warehouse and don't care about aesthetics or natural lighting, just minimum cost.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/03/2020 07:29 pm
Hanging?!

Good sir! Do I look like an architect?! :P
Nah the steel wall goes through than under the outer/inner walls.
It's too thin to see, but there is a steel base layer above the foundations, but under the walls
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/03/2020 07:44 pm

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

Of those "hundreds of ways," which one was the cheapest?

You can assume I want to construct a factory or warehouse and don't care about aesthetics or natural lighting, just minimum cost.
/quote]

That would be the 18m diameter horizontal pressure vessel Sir.  Proven for over fifty years!  Do you need radiation protection ?  We offer the ever popular regolith pile, for just a few dollars per cubic meter, or, for protection in case of one of those pesky depressurisation events, compressed regolith with rebar.
Any airlocks?  We have the standard 4m tubular for connection to the underground network, or surface airlocks, depending on your operations.
Will that be in Martian credits or US dollars?  We have special discounts for payment in Terran currencies.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/03/2020 07:53 pm
Hanging?!

Good sir! Do I look like an architect?! :P
Nah the steel wall goes through than under the outer/inner walls.
It's too thin to see, but there is a steel base layer above the foundations, but under the walls

It sounds like you're saying it isn't hanging, but structurally that's exactly what you've described. If the walls "anchor" the pressure uplift from the dome (with the "base layer"), then by equal-and-opposite-reaction that means the walls are effectively hanging from the dome (supporting not 100%, but a decent fraction of the walls' weight).

If the dome were replaced by a full hemisphere, that would keep the dome structure purely in tension (it needs to be strong in tension anyway to restrain the atmospheric pressure), avoiding the bending stress concentration at the rim. Of course the larger dome would have more mass. A compromise structure is probably optimal.

You'll also probably need some downward-angled "anchors" that project out from the steel wall into the bulk of the ballast wall. This prevents the steel sheet from simply "pulling out" the base layer tablecloth style.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/03/2020 08:28 pm

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

Of those "hundreds of ways," which one was the cheapest?

You can assume I want to construct a factory or warehouse and don't care about aesthetics or natural lighting, just minimum cost.

That would be the 18m diameter horizontal pressure vessel Sir.  Proven for over fifty years! Do you need radiation protection ?  We offer the ever popular regolith pile, for just a few dollars per cubic meter, or, for protection in case of one of those pesky depressurisation events, compressed regolith with rebar.
Any airlocks?  We have the standard 4m tubular for connection to the underground network, or surface airlocks, depending on your operations.

I need a flat floor for my forklifts, but I presume you'd just use Marscrete.

I like the role-play, but I'm not certain about the engineering. Is manufacturing and transporting and emplacing a monolithic ~60 foot diameter pressure vessel really going to be the cheapest option? Perhaps it is, but I'm open to other suggestions.

Also, I doubt even compressed and reinforced regolith would provide protection from depressurization. It's not the strength I doubt, it's the sealing.

Will that be in Martian credits or US dollars?  We have special discounts for payment in Terran currencies.

Heh, "Terran" always kills me. The real-life word is "terrestrial," but "Terran" is indeed a sci-fi staple, much like naming the Moon "Luna" or the Sun "Sol."
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 12:08 am

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

Of those "hundreds of ways," which one was the cheapest?

You can assume I want to construct a factory or warehouse and don't care about aesthetics or natural lighting, just minimum cost.

That would be the 18m diameter horizontal pressure vessel Sir.  Proven for over fifty years! Do you need radiation protection ?  We offer the ever popular regolith pile, for just a few dollars per cubic meter, or, for protection in case of one of those pesky depressurisation events, compressed regolith with rebar.
Any airlocks?  We have the standard 4m tubular for connection to the underground network, or surface airlocks, depending on your operations.

I need a flat floor for my forklifts, but I presume you'd just use Marscrete.

I like the role-play, but I'm not certain about the engineering. Is manufacturing and transporting and emplacing a monolithic ~60 foot diameter pressure vessel really going to be the cheapest option? Perhaps it is, but I'm open to other suggestions.

Also, I doubt even compressed and reinforced regolith would provide protection from depressurization. It's not the strength I doubt, it's the sealing.

Will that be in Martian credits or US dollars?  We have special discounts for payment in Terran currencies.

Heh, "Terran" always kills me. The real-life word is "terrestrial," but "Terran" is indeed a sci-fi staple, much like naming the Moon "Luna" or the Sun "Sol."
Yes indeed sir, we can provide a Marscrete floor over a regolith fill, very cheap.
Sorry sir, the reinforcement in the regolith is to keep it from collapsing onto your goods after a depressurization event.  We want to avoid adding insult to injury, don't we sir?

Language, sch a tricky tool to use. 

Goodness me you know real life Martians?  So lucky for you sir.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/04/2020 12:49 am
the reinforcement in the regolith is to keep it from collapsing onto your goods after a depressurization event

So you're suggesting I can replace a costly reinforced processed regolith (Marscrete, compressed regolith, something) shield with a cheap rubble pile if only the structure is self-supporting? An interesting avenue for optimization.

Clearly the inability to support the shielding regolith pile unpressurized is due to buckling failure, not yield failure. The weight of the shield is much less than the internal atmospheric pressure.

To restrain a 7.5 psia atmosphere with no margins would require 10.8 mm of 304L. I assume at least 2.25x margins (hefty by spaceship standards, but wimpy by building standards), so that makes 24.4 mm thickness.

Aside: at what point do we start to be limited by the maximum thickness we can weld?

Looking at buried culverts, and obvious solution presents itself: corrugation. Likely this would be in the form of an outer or inner corrugated "sleeve" welded on, since corrugating the pressure vessel itself would create a bellows effect.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 01:19 am
the reinforcement in the regolith is to keep it from collapsing onto your goods after a depressurization event

So you're suggesting I can replace a costly reinforced processed regolith (Marscrete, compressed regolith, something) shield with a cheap rubble pile if only the structure is self-supporting? An interesting avenue for optimization.

Clearly the inability to support the shielding regolith pile unpressurized is due to buckling failure, not yield failure. The weight of the shield is much less than the internal atmospheric pressure.

To restrain a 7.5 psia atmosphere with no margins would require 10.8 mm of 304L. I assume at least 2.25x margins (hefty by spaceship standards, but wimpy by building standards), so that makes 24.4 mm thickness.

Aside: at what point do we start to be limited by the maximum thickness we can weld?

Looking at buried culverts, and obvious solution presents itself: corrugation. Likely this would be in the form of an outer or inner corrugated "sleeve" welded on, since corrugating the pressure vessel itself would create a bellows effect.
Welding is not really thickness limited.  You can weld steel many inches thick and this is commonly done on sea going ships.  You need to do multiple passes.  It's quite an art, but once it's mastered it's just welding and can even be automated.
Yes, I would expect a large horizontal pressure vessel under loose regolith to buckle if it lost internal pressure.  A double or triple tube, such as the one illustrated here, would certainly fail.  If it's a single tube, however, then the regolith might not collapse and it could hold itself up.
Corrugation is a great idea for compression but useless in tension.  I don't know if the risk of pressure loss is sufficiently high to justify a corrugated structure versus strengthening the external regolith.
For the cheap industrial buildings you want to to purchase  ;) you would probably just line up a number of tubes. 
I expect the cube laws will work in our favor for once, on Mars.  It should be simpler than on Earth to build large cylindrical welded structures. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 01:27 am
Multipass welding patterns.

http://mewelding.com/multi-pass-welds/

Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/04/2020 07:17 am
Exactly, our steel walls are almost an inch thick, but doing multiple passes allows that to be constructed easily.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/04/2020 07:32 am
Speaking of which, did Nexus Aurora come up with any good resources/ideas on finding copper?
Well, the problem is the remote sensing information is too low to make out where proper Cu would be.

So we opted for a landing site near a lot of basalt rock and other ancient volcanic activity. As well as a ancient river bed, this gave us a large variety of different geological sources that we could tap into. The millions of meteorite craters would also have been a obvious candidates to find rare minerals.

Good to hear! We opted for the same.

We developed a Methalox heavy-haul automated train network that would be used to connect copper and ice mines to our city. 
Based on Standard-gauge, heavy haul numbers in Australia, and then compared to rocket flight estimates based on the project brief ($200/kg to Earth) and Starship. We determined that rail transport was economically superior up to 1,600km from our city centre.

That allowed us to locate our city near Tempe Terra or Chryse Planitia, and still have access to Thorium in the north-east, mineral deposits in out flow channels to the south, ice to the north and regions of volcanism in Tharsis to the south-west.

Note: we chose to use Methalox for long range heavy-haul as electrifying track is EXPENSIVE (our Transport guys works in Rail Infrastructure)
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 07/04/2020 09:55 am
Note: we chose to use Methalox for long range heavy-haul as electrifying track is EXPENSIVE (our Transport guys works in Rail Infrastructure)

Is it? Here on Earth, sure. But on Mars you could use the steel tracks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/04/2020 11:41 am
Note: we chose to use Methalox for long range heavy-haul as electrifying track is EXPENSIVE (our Transport guys works in Rail Infrastructure)

Is it? Here on Earth, sure. But on Mars you could use the steel tracks.

Yes it is, even third-rail electrification is expensive. The cost isn't just the physical systems like overhead or a third-rail, it's the electrical substations and other infrastructure.

And then you need to maintain that system... headaches all round
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/04/2020 02:58 pm
Speaking of which, did Nexus Aurora come up with any good resources/ideas on finding copper?
Well, the problem is the remote sensing information is too low to make out where proper Cu would be.

So we opted for a landing site near a lot of basalt rock and other ancient volcanic activity. As well as a ancient river bed, this gave us a large variety of different geological sources that we could tap into. The millions of meteorite craters would also have been a obvious candidates to find rare minerals.

Good to hear! We opted for the same.

We developed a Methalox heavy-haul automated train network that would be used to connect copper and ice mines to our city. 
Based on Standard-gauge, heavy haul numbers in Australia, and then compared to rocket flight estimates based on the project brief ($200/kg to Earth) and Starship. We determined that rail transport was economically superior up to 1,600km from our city centre.

That allowed us to locate our city near Tempe Terra or Chryse Planitia, and still have access to Thorium in the north-east, mineral deposits in out flow channels to the south, ice to the north and regions of volcanism in Tharsis to the south-west.

Note: we chose to use Methalox for long range heavy-haul as electrifying track is EXPENSIVE (our Transport guys works in Rail Infrastructure)
We also had multiple sites, but we where 38' South, and had multiple rail to 3 Bases. 1 in the equator for Farming (year round summer sun with fewer dust storms. And 2 at super low altitudes with good mining resources.

Rail beats anything!

We also decided to ignore the Mars societies farming recommendation of 15m2 of farming per person. It was based of a study using extremely high energy cost LED lit farms. We found that the opportunity cost of building open farms of 200m2 per person where way better. This is how we ended up with a equatorial farming outpost.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/04/2020 03:01 pm

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

Of those "hundreds of ways," which one was the cheapest?

You can assume I want to construct a factory or warehouse and don't care about aesthetics or natural lighting, just minimum cost.

Absolutely just tubes fused together.

We had a farm structure, filled with soil which is as cheap as you can do. The lower the diameter the cheaper it is up to about 5m diam. Lower diameter gives you better hoop-stress forces to work with, meaning less material overall.

Then we built a Radiation resistant version of that, using Mars-crete blocks on the sides and water on the roof. You will need a tent like structure over the water to stop it from sublimating away.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 03:14 pm
Speaking of which, did Nexus Aurora come up with any good resources/ideas on finding copper?
Well, the problem is the remote sensing information is too low to make out where proper Cu would be.

So we opted for a landing site near a lot of basalt rock and other ancient volcanic activity. As well as a ancient river bed, this gave us a large variety of different geological sources that we could tap into. The millions of meteorite craters would also have been a obvious candidates to find rare minerals.

Good to hear! We opted for the same.

We developed a Methalox heavy-haul automated train network that would be used to connect copper and ice mines to our city. 
Based on Standard-gauge, heavy haul numbers in Australia, and then compared to rocket flight estimates based on the project brief ($200/kg to Earth) and Starship. We determined that rail transport was economically superior up to 1,600km from our city centre.

That allowed us to locate our city near Tempe Terra or Chryse Planitia, and still have access to Thorium in the north-east, mineral deposits in out flow channels to the south, ice to the north and regions of volcanism in Tharsis to the south-west.

Note: we chose to use Methalox for long range heavy-haul as electrifying track is EXPENSIVE (our Transport guys works in Rail Infrastructure)
We also had multiple sites, but we where 38' South, and had multiple rail to 3 Bases. 1 in the equator for Farming (year round summer sun with fewer dust storms. And 2 at super low altitudes with good mining resources.

Rail beats anything!

We also decided to ignore the Mars societies farming recommendation of 15m2 of farming per person. It was based of a study using extremely high energy cost LED lit farms. We found that the opportunity cost of building open farms of 200m2 per person where way better. This is how we ended up with a equatorial farming outpost.
We followed a similar path, starting with a landing base at Arcadia Planitia with grow rooms and nuclear power with LEDs, and later extending down to Nicholson crater at the equator with greenhouses and mostly natural lighting for a more economical, if less dense, growing system.  We added orbital solar reflectors to increase yields.
We had our eye on possible black smokers remnants in the Medusae Fossae region for rare minerals.  But mostly we expected to use aluminium wire for most of the City State needs.
We did not investigate rail, which in retrospect may have been a mistake, for our main road between the north and the south.  We went for very large methalox powered vehicles in convoy systems.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 03:22 pm

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

Of those "hundreds of ways," which one was the cheapest?

You can assume I want to construct a factory or warehouse and don't care about aesthetics or natural lighting, just minimum cost.

Absolutely just tubes fused together.

We had a farm structure, filled with soil which is as cheap as you can do. The lower the diameter the cheaper it is up to about 5m diam. Lower diameter gives you better hoop-stress forces to work with, meaning less material overall.

Then we built a Radiation resistant version of that, using Mars-crete blocks on the sides and water on the roof. You will need a tent like structure over the water to stop it from sublimating away.
Our greenhouses are very similar, although a little larger as we settled on a basic 9m system.  But instead of a full basement we used a hollow one, filled with water for energy storage and agricultural use.  Movable insulated curtains for all and local reflectors in the north.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/04/2020 04:07 pm
We are actually still growing our city Idea and want to build an opensource VR city.

We have a discord with over 20 projects all trying to solve the Mars City Problem with over 100 people.
If you want to join, let me know, we still have a lot to do.

I hope you guys dont mind if I show your proposals on our Discord. Makes for good discussion to see what other people came up with.
Ill make sure I link to here and give your teams the recognition for the images.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 05:26 pm
We are actually still growing our city Idea and want to build an opensource VR city.

We have a discord with over 20 projects all trying to solve the Mars City Problem with over 100 people.
If you want to join, let me know, we still have a lot to do.

I hope you guys dont mind if I show your proposals on our Discord. Makes for good discussion to see what other people came up with.
Ill make sure I link to here and give your teams the recognition for the images.
I'll have to check with the rest of the team.  Don't see why not, that was the idea in posting them here, as far as the images go.  But for anything further it's a group decision, in particular for the more complicated design spreadsheets and such.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/04/2020 06:27 pm
We are actually still growing our city Idea and want to build an opensource VR city.

We have a discord with over 20 projects all trying to solve the Mars City Problem with over 100 people.
If you want to join, let me know, we still have a lot to do.

I hope you guys dont mind if I show your proposals on our Discord. Makes for good discussion to see what other people came up with.
Ill make sure I link to here and give your teams the recognition for the images.
I'll have to check with the rest of the team.  Don't see why not, that was the idea in posting them here, as far as the images go.  But for anything further it's a group decision, in particular for the more complicated design spreadsheets and such.

Yeah, same with me.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/04/2020 06:33 pm
Speaking of which, did Nexus Aurora come up with any good resources/ideas on finding copper?
Well, the problem is the remote sensing information is too low to make out where proper Cu would be.

So we opted for a landing site near a lot of basalt rock and other ancient volcanic activity. As well as a ancient river bed, this gave us a large variety of different geological sources that we could tap into. The millions of meteorite craters would also have been a obvious candidates to find rare minerals.

Good to hear! We opted for the same.

We developed a Methalox heavy-haul automated train network that would be used to connect copper and ice mines to our city. 
Based on Standard-gauge, heavy haul numbers in Australia, and then compared to rocket flight estimates based on the project brief ($200/kg to Earth) and Starship. We determined that rail transport was economically superior up to 1,600km from our city centre.

That allowed us to locate our city near Tempe Terra or Chryse Planitia, and still have access to Thorium in the north-east, mineral deposits in out flow channels to the south, ice to the north and regions of volcanism in Tharsis to the south-west.

Note: we chose to use Methalox for long range heavy-haul as electrifying track is EXPENSIVE (our Transport guys works in Rail Infrastructure)
We also had multiple sites, but we where 38' South, and had multiple rail to 3 Bases. 1 in the equator for Farming (year round summer sun with fewer dust storms. And 2 at super low altitudes with good mining resources.

Rail beats anything!

We also decided to ignore the Mars societies farming recommendation of 15m2 of farming per person. It was based of a study using extremely high energy cost LED lit farms. We found that the opportunity cost of building open farms of 200m2 per person where way better. This is how we ended up with a equatorial farming outpost.

We settled on 230m2, with a mass produced farm module. We probably could have optimised that part of our design better.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 06:58 pm
We have a very wide range, from 140 m2 per person for the grow room rich Northern settlement to nearly 300 m2 per person for the southern, mostly natural lighting settlement.  We also have a fair amount of bioreactors for extra protein.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 07/04/2020 07:19 pm
Haven't looked at the compendium myself: did anybody make a proposal consisting of primarily underground tunnels?

- That is, after all, what Elon thinks they will start out with on Mars. I also think it is the best idea until the colony is very advanced, i.e. years, if not decades, after first landing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/04/2020 07:42 pm
Haven't looked at the compendium myself: did anybody make a proposal consisting of primarily underground tunnels?

- That is, after all, what Elon thinks they will start out with on Mars. I also think it is the best idea until the colony is very advanced, i.e. years, if not decades, after first landing.
The latest discussion is about the 1 000 000 people City States.  So that's pretty advanced.  As far as the timeline goes, it could be decades or centuries.
 I think most of the proposals for the 1000 people settlement (last years contest) were underground, or at most with a few domes.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 07/04/2020 09:41 pm
Thanks, lamontagne, I was a bit foggy on that. Has last years' proposals been put online?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/04/2020 10:26 pm
Thanks, lamontagne, I was a bit foggy on that. Has last years' proposals been put online?

You can watch the top 10 on YouTube, the rest can be fo Me in the Mars Society's book
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/04/2020 10:34 pm
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/05/2020 01:24 am
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)
We're an order of magnitude larger.  Essentially for food production and all the industry related to it.  The underground grow rooms in particular are energy hogs. 
I guess you must have very efficient greenhouses.  We were very pessimistic as to their performances without artificial lighting to supplement production.  It's really the main energy parameter of the settlement.  All the rest is pretty straightforward, but in general we supposed higher energy use than what you seen to have used.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/05/2020 08:13 am
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)
We're an order of magnitude larger.  Essentially for food production and all the industry related to it.  The underground grow rooms in particular are energy hogs. 
I guess you must have very efficient greenhouses.  We were very pessimistic as to their performances without artificial lighting to supplement production.  It's really the main energy parameter of the settlement.  All the rest is pretty straightforward, but in general we supposed higher energy use than what you seen to have used.

Honestly we assumed powering the lights in a green house for all the food would be a complete non-starter on a large scale, given our 1000 person colony needed ~40MW for food.

We didn't think you could have a sane power output at those levels, unless you invented fusion.

Additionally, Bob Zubrin REALLY thinks that Mars is the only other place in the solar system you can do large scale farming, as "you can just use the existing day-night cycle"
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/05/2020 10:19 am
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)
We're an order of magnitude larger.  Essentially for food production and all the industry related to it.  The underground grow rooms in particular are energy hogs. 
I guess you must have very efficient greenhouses.  We were very pessimistic as to their performances without artificial lighting to supplement production.  It's really the main energy parameter of the settlement.  All the rest is pretty straightforward, but in general we supposed higher energy use than what you seen to have used.

Honestly we assumed powering the lights in a green house for all the food would be a complete non-starter on a large scale, given our 1000 person colony needed ~40MW for food.

We didn't think you could have a sane power output at those levels, unless you invented fusion.

Additionally, Bob Zubrin REALLY thinks that Mars is the only other place in the solar system you can do large scale farming, as "you can just use the existing day-night cycle"
I won't go against Bob Zubrin, and I agree that you can get food production from greenhouses on Mars. I just don't see how you can get better food production ratios than on Earth with about half the sunlight.  200 m2 per person means average yields of 50 tonnes per hectare.  Potatoes, perhaps, but corn, wheat or barley?
So our 50 GW roughly correlates with your initial 1000 people settlement?
Title: Re: Envisioning Amazing Martian Habitats
Post by: _MECO on 07/05/2020 10:52 am
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)

Forgive me if this is a dumb question. With multiple gigawatts' worth of nuclear reactors running on Mars, where exactly do you reject waste heat to? The atmosphere isn't exactly substantial enough for old-fashioned convective "radiators" to be practical.

What do you do? Run hot coolant into and out of the cold, fracked Martian soil as a reverse-geothermal scheme? Have there be giant red hot radiators shining it out into the sky? (Who can even build a reactor system where the "cold" reservoir is red hot, anyway?) My best guess would be to build the colony directly bordering or on Korolev crater, using mined ice to pull heat from reactor systems while producing valuable liquid water as a side product.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/05/2020 11:12 am
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)

Forgive me if this is a dumb question. With multiple gigawatts' worth of nuclear reactors running on Mars, where exactly do you reject waste heat to? The atmosphere isn't exactly substantial enough for old-fashioned convective "radiators" to be practical.

What do you do? Run hot coolant into and out of the cold, fracked Martian soil as a reverse-geothermal scheme? Have there be giant red hot radiators shining it out into the sky? (Who can even build a reactor system where the "cold" reservoir is red hot, anyway?) My best guess would be to build the colony directly bordering or on Korolev crater, using mined ice to pull heat from reactor systems while producing valuable liquid water as a side product.

The radiators don't need to be red hot, they just need to be very large.  For 6 GW of waste heat you need about 12 km2 at 300K.  The simplest solution is probably a very large number of plastic pipes.  You might also go for a large tent type structure with a lake, if you can find a spot with the right geometry and the amount of ice available is as high as expected in the mid latitudes.
But I expect most of the projects will simply use the greenhouses as radiators.  At 200 m2 per person, that's 200 km2 for 1 00 000 people, so that's a lot of radiators.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/05/2020 11:44 am
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)
We're an order of magnitude larger.  Essentially for food production and all the industry related to it.  The underground grow rooms in particular are energy hogs. 
I guess you must have very efficient greenhouses.  We were very pessimistic as to their performances without artificial lighting to supplement production.  It's really the main energy parameter of the settlement.  All the rest is pretty straightforward, but in general we supposed higher energy use than what you seen to have used.

Honestly we assumed powering the lights in a green house for all the food would be a complete non-starter on a large scale, given our 1000 person colony needed ~40MW for food.

We didn't think you could have a sane power output at those levels, unless you invented fusion.

Additionally, Bob Zubrin REALLY thinks that Mars is the only other place in the solar system you can do large scale farming, as "you can just use the existing day-night cycle"
I won't go against Bob Zubrin, and I agree that you can get food production from greenhouses on Mars. I just don't see how you can get better food production ratios than on Earth with about half the sunlight.  200 m2 per person means average yields of 50 tonnes per hectare.  Potatoes, perhaps, but corn, wheat or barley?
So our 50 GW roughly correlates with your initial 1000 people settlement?

Roughly, we estimated 100 MW for 1000 people, roughly half of which was for food production, but that won't scale linearly. Just in production alone there are better efficiencies with scale. So if you were going on powered lighting, 50GW sounds right to me.

We have 230 m2 per person, to provide excess, and a lot of our Second Floors we're dedicated to other crops, though more recreational like fruits or spices.

The one good thing about not relaying on internal greenhouses is we can scale a lot more easily. If 230m2 isn't enough, make more farm modules.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/05/2020 11:49 am
Now this ones sure to be interesting...

What did you lot settle on for power? Both levels and source? Last years were all over the shop with someone saying they could get away with something like 7MW, and someone else already hitting the 1GW mark... for 1000 people!!!

We calculated roughly 2.5 GWe would be needed for average industrial and societal needs, with potential spikes up to 3.5GWe depending on what was running.

To this end we decided on 4, 1GWe molten salt thorium reactors, for duty cycling and redundancy. These were backed up with a high temperature molten silicon storage system, and a low temperature storage system used for heating the colony
(IE, we kept our stored water at ~70oC by running the exhaust from the reactor through it... storage!...)

Forgive me if this is a dumb question. With multiple gigawatts' worth of nuclear reactors running on Mars, where exactly do you reject waste heat to? The atmosphere isn't exactly substantial enough for old-fashioned convective "radiators" to be practical.

What do you do? Run hot coolant into and out of the cold, fracked Martian soil as a reverse-geothermal scheme? Have there be giant red hot radiators shining it out into the sky? (Who can even build a reactor system where the "cold" reservoir is red hot, anyway?) My best guess would be to build the colony directly bordering or on Korolev crater, using mined ice to pull heat from reactor systems while producing valuable liquid water as a side product.

Short answer? The city.

Long answer, the heat will be rejected to our water storage, which will then be heat controlled by pumping the heated water to the habitats.

The whole city is likely to lose several gigawatts of heat naturally.

Additionally, waste heat is used to melt ice brought in via hopper wagons from the ice mines up north.

Finally, there are radiators connected to the system to further help regulate heat
Title: Re: Envisioning Amazing Martian Habitats
Post by: GregTheGrumpy on 07/05/2020 05:40 pm
Y'all,  This subject is becoming increasingly interesting to me.  I am gathering hints from this thread that there are sites and even competitions for this sort of thing.

How about a list of references (links if permitted) for those organizations?  I'd like to read up some more on how this stuff is progressing.

I know I'd like to go to Mars, I'd even go in the first wave with lots of risk and having to live in a burrow.  I'd want to see what folks are thinking about how to do immediate term, and slightly longer term living on Mars.

-gg
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/05/2020 08:52 pm
Y'all,  This subject is becoming increasingly interesting to me.  I am gathering hints from this thread that there are sites and even competitions for this sort of thing.

How about a list of references (links if permitted) for those organizations?  I'd like to read up some more on how this stuff is progressing.

I know I'd like to go to Mars, I'd even go in the first wave with lots of risk and having to live in a burrow.  I'd want to see what folks are thinking about how to do immediate term, and slightly longer term living on Mars.

-gg
Hi Greg, apart from NASASpaceflight.com itself, The Mars Society has held a number of contests on the subject, and NASA has had a few specific contests as well, in particular 3D printed habitats.  They have supported quite a bit of research.
The university of Vancouver has an active group.  Doing very specific things such as Martian airlocks.
The results of last year's contest for a 1000 person settlement is in a book called ''Mars Colonies: Plans for Settling the Red Planet”.
The Mars Society has Marspedia, as a WIKI on the subject of martian colonisation.


Most other sites are no longer active.  Interest in Martian architecture is a very niche subject  :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/05/2020 09:14 pm
the reinforcement in the regolith is to keep it from collapsing onto your goods after a depressurization event

So you're suggesting I can replace a costly reinforced processed regolith (Marscrete, compressed regolith, something) shield with a cheap rubble pile if only the structure is self-supporting? An interesting avenue for optimization.

Clearly the inability to support the shielding regolith pile unpressurized is due to buckling failure, not yield failure. The weight of the shield is much less than the internal atmospheric pressure.

To restrain a 7.5 psia atmosphere with no margins would require 10.8 mm of 304L. I assume at least 2.25x margins (hefty by spaceship standards, but wimpy by building standards), so that makes 24.4 mm thickness.

Aside: at what point do we start to be limited by the maximum thickness we can weld?

Looking at buried culverts, and obvious solution presents itself: corrugation. Likely this would be in the form of an outer or inner corrugated "sleeve" welded on, since corrugating the pressure vessel itself would create a bellows effect.
Welding is not really thickness limited.  You can weld steel many inches thick and this is commonly done on sea going ships.  You need to do multiple passes.  It's quite an art, but once it's mastered it's just welding and can even be automated.

Ok, so the limit might not be technological, but economic.

At what point does the cost per cm2 of multi-pass welding exceed single-pass welding?

Or the cost to manufacture a certain thickness of metal.

Yes, I would expect a large horizontal pressure vessel under loose regolith to buckle if it lost internal pressure.  A double or triple tube, such as the one illustrated here, would certainly fail.  If it's a single tube, however, then the regolith might not collapse and it could hold itself up.

If it's surrounded by regolith on all sides, multiple tubes should behave the same as one tube. Multiple tubes might even be stronger, since the tubes on either side can resist the horizontal movement as it starts to "oval."

Corrugation is a great idea for compression but useless in tension.  I don't know if the risk of pressure loss is sufficiently high to justify a corrugated structure versus strengthening the external regolith.

Well, I don't know if the decision depends on the risk magnitude. If they both hold up the weight, it should only depend on which option is cheaper.

For the cheap industrial buildings you want to to purchase  ;) you would probably just line up a number of tubes.

This is quite limiting on the factory layout. Some sort of "planar" approach would likely find a lot of demand, even if it is a tad more expensive.

Maybe your idea would be cheapest, but I still don't know. There's tantalizing hints to suggest that some better option is out there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/05/2020 09:33 pm

As we got into the detail, we discovered that there are literally hundreds of ways to make buildings with all the radiation shielding you need. Making the pressure vessels is the biggest pain, but not that bad.

Of those "hundreds of ways," which one was the cheapest?

You can assume I want to construct a factory or warehouse and don't care about aesthetics or natural lighting, just minimum cost.

Absolutely just tubes fused together.

We had a farm structure, filled with soil which is as cheap as you can do. The lower the diameter the cheaper it is up to about 5m diam. Lower diameter gives you better hoop-stress forces to work with, meaning less material overall.

Then we built a Radiation resistant version of that, using Mars-crete blocks on the sides and water on the roof. You will need a tent like structure over the water to stop it from sublimating away.

I love it.

I wonder, if horizontally-joined cylinders are more economic than lone cylinders, would vertically-and-horizontally-joined cylinders be more economic than horizontally-joined cylinders? See my Waffle Hab structural proposal (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641).

The genesis of that idea started from horizontal cylinders (see? I see you lamontagne :D), then rows of cylinders, then stacks of rows...

Lower levels could share the radiation shielding of upper levels, reducing overall build cost. Habitable space could be located below greenhouse space, incrementally benefiting from the shielding mass of soil, plant biomass, and hydroponics water.

Some things will get more expensive with height (eg the surrounding wall shield), so obviously infinite height isn't optimal. But I wonder if the optimal number of vertical levels is 1, or some other number (naturally it would vary from case-to-case).


Note that in the illustration below the "end caps" are shown as 180° half-cylinders, but in reality a smaller angle would be more optimal in some cases. Silhouettes are solely to illustrate the relative amount of "useful" habitable space.


edit: pasting relevant comments from the O'Neill cylinder thread.


As an aside, the traditional conception of an O'Neill cylinder as a "big empty room" surrounded by a "big hulking wall" always struck me as unrealistic. The former wastes precious/expensive pressurized, conditioned, and radiation shielded volume, and the latter has no sense of redundancy or right-sizing (rather like a Victorian gentleman imagining skyscrapers as having one giant central column  :) ).

Instead, I propose that a more realistic model would be modular steel construction. Instead of putting all the atmospheric pressure load in one giant outer wall, tension would be restrained by a "distributed" space-filling grid of beams, which also provide support for internal floors and walls (just like a skyscraper have "distributed" columns to support them against gravity).
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/06/2020 09:14 am

I love it.

I wonder, if horizontally-joined cylinders are more economic than lone cylinders, would vertically-and-horizontally-joined cylinders be more economic than horizontally-joined cylinders? See my Waffle Hab structural proposal (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641).

The genesis of that idea started from horizontal cylinders (see? I see you lamontagne :D), then rows of cylinders, then stacks of rows...

Lower levels could share the radiation shielding of upper levels, reducing overall build cost. Habitable space could be located below greenhouse space, incrementally benefiting from the shielding mass of soil, plant biomass, and hydroponics water.

Some things will get more expensive with height (eg the surrounding wall shield), so obviously infinite height isn't optimal. But I wonder if the optimal number of vertical levels is 1, or some other number (naturally it would vary from case-to-case).


Note that in the illustration below the "end caps" are shown as 180° half-cylinders, but in reality a smaller angle would be more optimal in some cases. Silhouettes are solely to illustrate the relative amount of "useful" habitable space.


edit: pasting relevant comments from the O'Neill cylinder thread.


As an aside, the traditional conception of an O'Neill cylinder as a "big empty room" surrounded by a "big hulking wall" always struck me as unrealistic. The former wastes precious/expensive pressurized, conditioned, and radiation shielded volume, and the latter has no sense of redundancy or right-sizing (rather like a Victorian gentleman imagining skyscrapers as having one giant central column  :) ).

Instead, I propose that a more realistic model would be modular steel construction. Instead of putting all the atmospheric pressure load in one giant outer wall, tension would be restrained by a "distributed" space-filling grid of beams, which also provide support for internal floors and walls (just like a skyscraper have "distributed" columns to support them against gravity).
Your "waffle hab" structure is exactly what we ended up doing for one structure type. The pic below is essentially that. The side walls hide quite a bit of structure, and double as radiation shielding. You can also flip your domes upside down, then you turn tensile structures into compression structures. We did this for some ground structures. Concrete is abundant on Mars.

To answer the "what do you do with all the heat from nuclear", we just used the roof water. The city is HUGE, so we have a massive surface area of water that can be used to cool our nuclear reactors down. We needed the water for radiation protection, cooling nuclear power and fish farms. All in one.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/06/2020 10:57 am

I love it.

I wonder, if horizontally-joined cylinders are more economic than lone cylinders, would vertically-and-horizontally-joined cylinders be more economic than horizontally-joined cylinders? See my Waffle Hab structural proposal (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641).

The genesis of that idea started from horizontal cylinders (see? I see you lamontagne :D), then rows of cylinders, then stacks of rows...

Lower levels could share the radiation shielding of upper levels, reducing overall build cost. Habitable space could be located below greenhouse space, incrementally benefiting from the shielding mass of soil, plant biomass, and hydroponics water.

Some things will get more expensive with height (eg the surrounding wall shield), so obviously infinite height isn't optimal. But I wonder if the optimal number of vertical levels is 1, or some other number (naturally it would vary from case-to-case).


Note that in the illustration below the "end caps" are shown as 180° half-cylinders, but in reality a smaller angle would be more optimal in some cases. Silhouettes are solely to illustrate the relative amount of "useful" habitable space.


edit: pasting relevant comments from the O'Neill cylinder thread.


As an aside, the traditional conception of an O'Neill cylinder as a "big empty room" surrounded by a "big hulking wall" always struck me as unrealistic. The former wastes precious/expensive pressurized, conditioned, and radiation shielded volume, and the latter has no sense of redundancy or right-sizing (rather like a Victorian gentleman imagining skyscrapers as having one giant central column  :) ).

Instead, I propose that a more realistic model would be modular steel construction. Instead of putting all the atmospheric pressure load in one giant outer wall, tension would be restrained by a "distributed" space-filling grid of beams, which also provide support for internal floors and walls (just like a skyscraper have "distributed" columns to support them against gravity).
Your "waffle hab" structure is exactly what we ended up doing for one structure type. The pic below is essentially that. The side walls hide quite a bit of structure, and double as radiation shielding. You can also flip your domes upside down, then you turn tensile structures into compression structures. We did this for some ground structures. Concrete is abundant on Mars.

To answer the "what do you do with all the heat from nuclear", we just used the roof water. The city is HUGE, so we have a massive surface area of water that can be used to cool our nuclear reactors down. We needed the water for radiation protection, cooling nuclear power and fish farms. All in one.

Same! Though not the water in the roof. You need ALOT of water for 1,000,000 people, and it can pull double or even triple duty for a number of things.

I'll admit, the biggest concern I have with a 'waffle' design is maunufactureability and maintenance. Going for a vertical cyclinder (silo) still has problems with space on the edges, but it's not unworkable. They are perfect for storage of various types.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/06/2020 02:34 pm

I love it.

I wonder, if horizontally-joined cylinders are more economic than lone cylinders, would vertically-and-horizontally-joined cylinders be more economic than horizontally-joined cylinders? See my Waffle Hab structural proposal (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641).

The genesis of that idea started from horizontal cylinders (see? I see you lamontagne :D), then rows of cylinders, then stacks of rows...

Lower levels could share the radiation shielding of upper levels, reducing overall build cost. Habitable space could be located below greenhouse space, incrementally benefiting from the shielding mass of soil, plant biomass, and hydroponics water.

Some things will get more expensive with height (eg the surrounding wall shield), so obviously infinite height isn't optimal. But I wonder if the optimal number of vertical levels is 1, or some other number (naturally it would vary from case-to-case).


Note that in the illustration below the "end caps" are shown as 180° half-cylinders, but in reality a smaller angle would be more optimal in some cases. Silhouettes are solely to illustrate the relative amount of "useful" habitable space.


edit: pasting relevant comments from the O'Neill cylinder thread.


As an aside, the traditional conception of an O'Neill cylinder as a "big empty room" surrounded by a "big hulking wall" always struck me as unrealistic. The former wastes precious/expensive pressurized, conditioned, and radiation shielded volume, and the latter has no sense of redundancy or right-sizing (rather like a Victorian gentleman imagining skyscrapers as having one giant central column  :) ).

Instead, I propose that a more realistic model would be modular steel construction. Instead of putting all the atmospheric pressure load in one giant outer wall, tension would be restrained by a "distributed" space-filling grid of beams, which also provide support for internal floors and walls (just like a skyscraper have "distributed" columns to support them against gravity).
Your "waffle hab" structure is exactly what we ended up doing for one structure type. The pic below is essentially that. The side walls hide quite a bit of structure, and double as radiation shielding. You can also flip your domes upside down, then you turn tensile structures into compression structures. We did this for some ground structures. Concrete is abundant on Mars.

To answer the "what do you do with all the heat from nuclear", we just used the roof water. The city is HUGE, so we have a massive surface area of water that can be used to cool our nuclear reactors down. We needed the water for radiation protection, cooling nuclear power and fish farms. All in one.

With your concrete, you can also mix in gypsum or some other hydrated mineral. Having a little hydrogen makes a huge difference. I can see you use a lot of radiation sidewalls as well. I look forward to seeing your team's full submission. Also - are you based in South Africa?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/06/2020 03:24 pm
With your concrete, you can also mix in gypsum or some other hydrated mineral. Having a little hydrogen makes a huge difference. I can see you use a lot of radiation sidewalls as well. I look forward to seeing your team's full submission. Also - are you based in South Africa?
We went with the idea that, if we gave near 100% radiation protection inside of habitats, then we can have other structures, such as farms or large social areas (dome type structures) without radiation protection.
For every 20 hours under Rad protection, you can spend 5 hours out of it, and still have a less than 50msv a year exposure.
We are interviewing a radiation medical expert about this later today to see if he agrees with the approach.

Yeah, im from South Africa, how did you know?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/06/2020 04:13 pm
With your concrete, you can also mix in gypsum or some other hydrated mineral. Having a little hydrogen makes a huge difference. I can see you use a lot of radiation sidewalls as well. I look forward to seeing your team's full submission. Also - are you based in South Africa?
We went with the idea that, if we gave near 100% radiation protection inside of habitats, then we can have other structures, such as farms or large social areas (dome type structures) without radiation protection.
For every 20 hours under Rad protection, you can spend 5 hours out of it, and still have a less than 50msv a year exposure.
We are interviewing a radiation medical expert about this later today to see if he agrees with the approach.

Yeah, im from South Africa, how did you know?
It's in your signature, to the left of your posts ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/06/2020 04:14 pm
With your concrete, you can also mix in gypsum or some other hydrated mineral. Having a little hydrogen makes a huge difference. I can see you use a lot of radiation sidewalls as well. I look forward to seeing your team's full submission. Also - are you based in South Africa?
We went with the idea that, if we gave near 100% radiation protection inside of habitats, then we can have other structures, such as farms or large social areas (dome type structures) without radiation protection.
For every 20 hours under Rad protection, you can spend 5 hours out of it, and still have a less than 50msv a year exposure.
We are interviewing a radiation medical expert about this later today to see if he agrees with the approach.

Yeah, im from South Africa, how did you know?
We did the same.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/06/2020 04:38 pm
Quote
Yeah, im from South Africa, how did you know?
It's in your signature, to the left of your posts ;-)
You can tell im a genius!  ;D
lol

edit I am, but the rest of the team is from around the world. I think we have almost every time zone now.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/06/2020 06:46 pm
Quote
Yeah, im from South Africa, how did you know?
It's in your signature, to the left of your posts ;-)
You can tell im a genius!  ;D
lol

edit I am, but the rest of the team is from around the world. I think we have almost every time zone now.

<- also South African - hello from Kimberley, if there's a bright centre to the universe I'm in the farthest place from it and all that. Thank goodness for Discord and D&D, I've managed to stay sane here during the lockdown :P

Anyway, I was toying with transparent greenhouses and wondering how to get them down to a decent diameter where you can pressurise them to a reasonable level and also make them out of something cheap and easy to manufacture like LDPE, and how to get enough light in, and not have them freeze during the night and roast during the day (because that is a thing with greenhouses, esp. in vacuum and low g). And also cut down on rads.

At first I thought, build them vertically? But that still shadows the plant trays during noon, so I thought - what the heck, these are pressurised tubes. You can do a lot with them. So angle them. Though a slope wouldn't be necessary, there are plenty of slopes on Mars, and you'll want to be on a slope to roll out dirt-cheap solar panels and maybe drill tunnels for a settlement. By angling the tube, you also make the diameter needed to accommodate a human much smaller - at 45 degree, you can make a 2m high accessway take up only 1.5m diameter (including some fudge factor for steps etc). This way, most of the plant trays are fully exposed to the sun for most of the day as long as they aren't stacked too close. Also, during northern hemisphere winter, they benefit from the larger sun by being less shadowed. Additional sunlight can be reflected by mirror farms on the plain below the slope.

Argon is a good insulator (I saw this from the Mars Ice House design), plus it's waste product from extracting nitrogen so pockets of these will offer some insulation. A slope means that hot air will rise up through the greenhouse, also creating sufficient airflow for the leaves (another issue). Finally, being on a slope will cut the radiation dose by terrain blocking. A flat 45 degree slope will cut it by about 1/4, a 30 degree slop by 1/6 (more common on Mars). The adjacent greenhouses will also cut down the radiation dose depending on how close they are and what's in them. Terrible sketch attached.

Title: Re: Envisioning Amazing Martian Habitats
Post by: rakaydos on 07/06/2020 10:16 pm
Quote
Yeah, im from South Africa, how did you know?
It's in your signature, to the left of your posts ;-)
You can tell im a genius!  ;D
lol

edit I am, but the rest of the team is from around the world. I think we have almost every time zone now.

<- also South African - hello from Kimberley, if there's a bright centre to the universe I'm in the farthest place from it and all that. Thank goodness for Discord and D&D, I've managed to stay sane here during the lockdown :P

Anyway, I was toying with transparent greenhouses and wondering how to get them down to a decent diameter where you can pressurise them to a reasonable level and also make them out of something cheap and easy to manufacture like LDPE, and how to get enough light in, and not have them freeze during the night and roast during the day (because that is a thing with greenhouses, esp. in vacuum and low g). And also cut down on rads.

At first I thought, build them vertically? But that still shadows the plant trays during noon, so I thought - what the heck, these are pressurised tubes. You can do a lot with them. So angle them. Though a slope wouldn't be necessary, there are plenty of slopes on Mars, and you'll want to be on a slope to roll out dirt-cheap solar panels and maybe drill tunnels for a settlement. By angling the tube, you also make the diameter needed to accommodate a human much smaller - at 45 degree, you can make a 2m high accessway take up only 1.5m diameter (including some fudge factor for steps etc). This way, most of the plant trays are fully exposed to the sun for most of the day as long as they aren't stacked too close. Also, during northern hemisphere winter, they benefit from the larger sun by being less shadowed. Additional sunlight can be reflected by mirror farms on the plain below the slope.

Argon is a good insulator (I saw this from the Mars Ice House design), plus it's waste product from extracting nitrogen so pockets of these will offer some insulation. A slope means that hot air will rise up through the greenhouse, also creating sufficient airflow for the leaves (another issue). Finally, being on a slope will cut the radiation dose by terrain blocking. A flat 45 degree slope will cut it by about 1/4, a 30 degree slop by 1/6 (more common on Mars). The adjacent greenhouses will also cut down the radiation dose depending on how close they are and what's in them. Terrible sketch attached.
Interesting. I'll also note that the human-accessways can be in the section shadowed by the layer above, maximizing the utilization of each layer's access to sunlight.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/07/2020 07:24 am

<- also South African - hello from Kimberley, if there's a bright centre to the universe I'm in the farthest place from it and all that. Thank goodness for Discord and D&D, I've managed to stay sane here during the lockdown :P

Anyway, I was toying with transparent greenhouses and wondering how to get them down to a decent diameter where you can pressurise them to a reasonable level and also make them out of something cheap and easy to manufacture like LDPE, and how to get enough light in, and not have them freeze during the night and roast during the day (because that is a thing with greenhouses, esp. in vacuum and low g). And also cut down on rads.

At first I thought, build them vertically? But that still shadows the plant trays during noon, so I thought - what the heck, these are pressurised tubes. You can do a lot with them. So angle them. Though a slope wouldn't be necessary, there are plenty of slopes on Mars, and you'll want to be on a slope to roll out dirt-cheap solar panels and maybe drill tunnels for a settlement. By angling the tube, you also make the diameter needed to accommodate a human much smaller - at 45 degree, you can make a 2m high accessway take up only 1.5m diameter (including some fudge factor for steps etc). This way, most of the plant trays are fully exposed to the sun for most of the day as long as they aren't stacked too close. Also, during northern hemisphere winter, they benefit from the larger sun by being less shadowed. Additional sunlight can be reflected by mirror farms on the plain below the slope.

Argon is a good insulator (I saw this from the Mars Ice House design), plus it's waste product from extracting nitrogen so pockets of these will offer some insulation. A slope means that hot air will rise up through the greenhouse, also creating sufficient airflow for the leaves (another issue). Finally, being on a slope will cut the radiation dose by terrain blocking. A flat 45 degree slope will cut it by about 1/4, a 30 degree slop by 1/6 (more common on Mars). The adjacent greenhouses will also cut down the radiation dose depending on how close they are and what's in them. Terrible sketch attached.
Hello from Durban!

This is what we did with our green houses.

The image is a 15m radius tube. Girders on top and bottom to pull the cylinders together with tension rods. These girders have cranes that run between them, and support farming equipment and robots.

Thermally, you receive 580W/m2 at peak sun altitude on Mars. Worst case you lose about 400W/m2 after sunset.

There are 3 ways to neutralize the heat loss/gain that we found.

Option 1 -  we proposed a material that has a Cu(Cl2) LiClO4 paste inside a laminated polymer skin. The past turns reflective (90% in the visible spectrum) when given a small charge. This means that our entire farms would turn reflective at night to radiate heat back in at night. You only need about 70% reflectivity at night to have a neutral heat loss/gain. If you get too hot during the day, you turn the system on.

Option 2 - Image 2 below, same as above, but we pulled a material over our farms that has a reflective coating at the bottom. This included a dust removal system in the rollers.

Option 3 - Waste heat from nuclear, there is so much heat from those things.

We initially had all kinds of plans to orientate out farms on slopes ext. But once you move farms close to the equator, you dont really have to. Sun from above is great.
The other things comes down to ease of use and long term energy cost. If its easier to just build more farms than more efficient ones, we opted to build more.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/07/2020 12:27 pm
Hello from Durban!

This is what we did with our green houses.

The image is a 15m radius tube. Girders on top and bottom to pull the cylinders together with tension rods. These girders have cranes that run between them, and support farming equipment and robots.

Thermally, you receive 580W/m2 at peak sun altitude on Mars. Worst case you lose about 400W/m2 after sunset.

There are 3 ways to neutralize the heat loss/gain that we found.

Option 1 -  we proposed a material that has a Cu(Cl2) LiClO4 paste inside a laminated polymer skin. The past turns reflective (90% in the visible spectrum) when given a small charge. This means that our entire farms would turn reflective at night to radiate heat back in at night. You only need about 70% reflectivity at night to have a neutral heat loss/gain. If you get too hot during the day, you turn the system on.

Option 2 - Image 2 below, same as above, but we pulled a material over our farms that has a reflective coating at the bottom. This included a dust removal system in the rollers.

Option 3 - Waste heat from nuclear, there is so much heat from those things.

We initially had all kinds of plans to orientate out farms on slopes ext. But once you move farms close to the equator, you dont really have to. Sun from above is great.
The other things comes down to ease of use and long term energy cost. If its easier to just build more farms than more efficient ones, we opted to build more.

Quantity has a quality of its own... reminds me a bit of Surviving Mars,

I like the idea of having a more regional economy. It's also much more attractive to government-level investors who want their own little base or colony represented on the red planet, just put them adjacent to the main trade route. Diversity and redundancy are good things, although being dependent on rail makes it a little vulnerable. But before then I suppose there'll be a road freight system which can always be a fallback (and service communities along the way).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/07/2020 12:43 pm
Hello from Durban!

This is what we did with our green houses.

The image is a 15m radius tube. Girders on top and bottom to pull the cylinders together with tension rods. These girders have cranes that run between them, and support farming equipment and robots.

Thermally, you receive 580W/m2 at peak sun altitude on Mars. Worst case you lose about 400W/m2 after sunset.

There are 3 ways to neutralize the heat loss/gain that we found.

Option 1 -  we proposed a material that has a Cu(Cl2) LiClO4 paste inside a laminated polymer skin. The past turns reflective (90% in the visible spectrum) when given a small charge. This means that our entire farms would turn reflective at night to radiate heat back in at night. You only need about 70% reflectivity at night to have a neutral heat loss/gain. If you get too hot during the day, you turn the system on.

Option 2 - Image 2 below, same as above, but we pulled a material over our farms that has a reflective coating at the bottom. This included a dust removal system in the rollers.

Option 3 - Waste heat from nuclear, there is so much heat from those things.

We initially had all kinds of plans to orientate out farms on slopes ext. But once you move farms close to the equator, you dont really have to. Sun from above is great.
The other things comes down to ease of use and long term energy cost. If its easier to just build more farms than more efficient ones, we opted to build more.

Quantity has a quality of its own... reminds me a bit of Surviving Mars,

I like the idea of having a more regional economy. It's also much more attractive to government-level investors who want their own little base or colony represented on the red planet, just put them adjacent to the main trade route. Diversity and redundancy are good things, although being dependent on rail makes it a little vulnerable. But before then I suppose there'll be a road freight system which can always be a fallback (and service communities along the way).

Given the lack of water or a thick atmosphere, there really are only 3 ways to move large quantities of goods, Rail, Road or Rocket.

These will almost certainly follow similar economics to Rail, Road and Air travel here on Earth, where Rail is used to connect areas of high traffic for lower costs, Road for specific or less travelled areas and Rocket for high speed, long distance. Bulk goods like grains, ores and ice will travel via Rail, with rail and road competing for other goods or 'Intermodal'. From personal experience I'll say intermodal is more difficult for Rail to turn a profit on as it has to compete with Road, which have less infratructure cost...Trucking companies don't also have to maintain the roads.

The one main difference for Road transport is that it may have less of a defined 'Road' and have bulkier machines .
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/07/2020 02:27 pm

<- also South African - hello from Kimberley, if there's a bright centre to the universe I'm in the farthest place from it and all that. Thank goodness for Discord and D&D, I've managed to stay sane here during the lockdown :P

Anyway, I was toying with transparent greenhouses and wondering how to get them down to a decent diameter where you can pressurise them to a reasonable level and also make them out of something cheap and easy to manufacture like LDPE, and how to get enough light in, and not have them freeze during the night and roast during the day (because that is a thing with greenhouses, esp. in vacuum and low g). And also cut down on rads.

At first I thought, build them vertically? But that still shadows the plant trays during noon, so I thought - what the heck, these are pressurised tubes. You can do a lot with them. So angle them. Though a slope wouldn't be necessary, there are plenty of slopes on Mars, and you'll want to be on a slope to roll out dirt-cheap solar panels and maybe drill tunnels for a settlement. By angling the tube, you also make the diameter needed to accommodate a human much smaller - at 45 degree, you can make a 2m high accessway take up only 1.5m diameter (including some fudge factor for steps etc). This way, most of the plant trays are fully exposed to the sun for most of the day as long as they aren't stacked too close. Also, during northern hemisphere winter, they benefit from the larger sun by being less shadowed. Additional sunlight can be reflected by mirror farms on the plain below the slope.

Argon is a good insulator (I saw this from the Mars Ice House design), plus it's waste product from extracting nitrogen so pockets of these will offer some insulation. A slope means that hot air will rise up through the greenhouse, also creating sufficient airflow for the leaves (another issue). Finally, being on a slope will cut the radiation dose by terrain blocking. A flat 45 degree slope will cut it by about 1/4, a 30 degree slop by 1/6 (more common on Mars). The adjacent greenhouses will also cut down the radiation dose depending on how close they are and what's in them. Terrible sketch attached.
Hello from Durban!

This is what we did with our green houses.

The image is a 15m radius tube. Girders on top and bottom to pull the cylinders together with tension rods. These girders have cranes that run between them, and support farming equipment and robots.

Thermally, you receive 580W/m2 at peak sun altitude on Mars. Worst case you lose about 400W/m2 after sunset.

There are 3 ways to neutralize the heat loss/gain that we found.

Option 1 -  we proposed a material that has a Cu(Cl2) LiClO4 paste inside a laminated polymer skin. The past turns reflective (90% in the visible spectrum) when given a small charge. This means that our entire farms would turn reflective at night to radiate heat back in at night. You only need about 70% reflectivity at night to have a neutral heat loss/gain. If you get too hot during the day, you turn the system on.

Option 2 - Image 2 below, same as above, but we pulled a material over our farms that has a reflective coating at the bottom. This included a dust removal system in the rollers.

Option 3 - Waste heat from nuclear, there is so much heat from those things.

We initially had all kinds of plans to orientate out farms on slopes ext. But once you move farms close to the equator, you dont really have to. Sun from above is great.
The other things comes down to ease of use and long term energy cost. If its easier to just build more farms than more efficient ones, we opted to build more.
We did pretty much the same, but with single cylinders and a diameter of  9 to 18m depending on the 'generation'.
We use two systems depending on location:  a vacuum insulation curtain for the night, in a roll by the greenhouse, or larger reflectors on poles with cables, than can be drawn in for the night.  Heating uses waste heat from the settlements.
Instead or a suspended crane we have a rolling crane, with a water line on a large reel.  Each side module is 500m long and the crane can move between modules at the central connecting module.  The greenhouses follow contour lines of the sloped areas.  For the most recent greenhouses we used an evolution of bendable glass sheets, with steel wire retaining systems.  But likely, many other systems have been tried over the years.
https://www.corning.com/worldwide/en/innovation/corning-emerging-innovations/corning-willow-glass.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/07/2020 02:34 pm
To supplement natural lighting our settlers have recently started using diffracting orbital mirrors for solar cell farms and greenhouse arrays, as per the paper by Rigel Woida.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/07/2020 07:02 pm

I love it.

I wonder, if horizontally-joined cylinders are more economic than lone cylinders, would vertically-and-horizontally-joined cylinders be more economic than horizontally-joined cylinders? See my Waffle Hab structural proposal (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1921641#msg1921641).

The genesis of that idea started from horizontal cylinders (see? I see you lamontagne :D), then rows of cylinders, then stacks of rows...

Lower levels could share the radiation shielding of upper levels, reducing overall build cost. Habitable space could be located below greenhouse space, incrementally benefiting from the shielding mass of soil, plant biomass, and hydroponics water.

Some things will get more expensive with height (eg the surrounding wall shield), so obviously infinite height isn't optimal. But I wonder if the optimal number of vertical levels is 1, or some other number (naturally it would vary from case-to-case).


Note that in the illustration below the "end caps" are shown as 180° half-cylinders, but in reality a smaller angle would be more optimal in some cases. Silhouettes are solely to illustrate the relative amount of "useful" habitable space.


edit: pasting relevant comments from the O'Neill cylinder thread.


As an aside, the traditional conception of an O'Neill cylinder as a "big empty room" surrounded by a "big hulking wall" always struck me as unrealistic. The former wastes precious/expensive pressurized, conditioned, and radiation shielded volume, and the latter has no sense of redundancy or right-sizing (rather like a Victorian gentleman imagining skyscrapers as having one giant central column  :) ).

Instead, I propose that a more realistic model would be modular steel construction. Instead of putting all the atmospheric pressure load in one giant outer wall, tension would be restrained by a "distributed" space-filling grid of beams, which also provide support for internal floors and walls (just like a skyscraper have "distributed" columns to support them against gravity).
Your "waffle hab" structure is exactly what we ended up doing for one structure type. The pic below is essentially that. The side walls hide quite a bit of structure, and double as radiation shielding. You can also flip your domes upside down, then you turn tensile structures into compression structures. We did this for some ground structures. Concrete is abundant on Mars.

To answer the "what do you do with all the heat from nuclear", we just used the roof water. The city is HUGE, so we have a massive surface area of water that can be used to cool our nuclear reactors down. We needed the water for radiation protection, cooling nuclear power and fish farms. All in one.

I can identify the vertical tension members and how they work, but I can't comprehend the horizontal tension members. They seem "broken" in this diagram, and some of the lateral "domes" I would expect seem to be missing.

Flat exterior walls might be supported by a structure with sufficient bending strength, but I assume there's a good reason why terrestrial pressure vessels never use flat walls to separate pressurized and non-pressurized volumes (probably something about membrane structures (https://en.wikipedia.org/wiki/Membrane_structure)).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/07/2020 08:15 pm
[snip]

Hello from Durban!

This is what we did with our green houses.

The image is a 15m radius tube. Girders on top and bottom to pull the cylinders together with tension rods. These girders have cranes that run between them, and support farming equipment and robots.

Yup, this is exactly my thinking: a girder to restrain where the cylinders join, and tension rods (or I-beams) connecting them.

You could similarly do this for the walls, making multiple levels. Instead of a gravity structure with its familiar "forest" of posts, you'd have a 3D cubic grid/lattice of posts. This should lend itself well to prefab modular construction, limiting in-situ manufacturing to a small set of standardized parts.

The challenge, of course, is assembly. You're probably not going to see space-suited construction workers, so this would likely involve specialized equipment and/or components designed to self-deploy.

Of course installing a 9 m diameter cylinder building also requires specialized oversized moving equipment. This equipment is arguably more general-purpose (depending on the design of the "prefab assembly bots"), but you still incur a cost every time you need to use it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/07/2020 09:59 pm
Pressure vessels have some interesting characteristics:
If you increase the diameter, you thicken the walls, but for the same interior volume the total amount of metal in the wall remains the same.  In other words, of you double the diameter you double the wall thickness, as it is a direct ratio.  But you also increase the volume to the square of the increase.  To get the same volume increase with your initial cylinder, you will need to make it longer by the square of the increase of the diameter.  So the amount of metal is the same for a large or a small cylinder, at the same pressure for the same total volume. 
This means that for a large settlement you may want to go with larger pressure vessels, to get better usage of the space.  The are construction issues, of course. that limit the size that is buildable.

The pressure times the volume is equal to the energy in the pressure vessel.  In fact, 1Pa x 1m3 = 1joule.  So even if you subdivide the pressure vessel into a number of open cells, the overall energy contained by the structure will be the same, (pretty certain, but it's been a long time!) and eventually, the amount of material for fabrication will be the same.  It is just the shape that will change.  So there is no material gain in using compound lateral tanks with beams as far as material costs go.  There is only a gain in dimensions and accessibility in one dimension or two dimensions for the one or two dimensions system.

Another interesting element is that for a spherical shape, the strain in the wall is reduced by 50%.  So a truly spherical pressure vessel has thinner walls and is more cost effective.  However, architecturally the sphere is a pain to use.  Hence the cylinders. 

So to create the cheapest volume of space for the settlement, spheres would be optimum as far as volume goes.  So it you are storing water, gases or similar fluid items, use spheres as much as possible.

If you are storing cargo that needs to be accessible, single floor building are usually the best. To avoid wasting a lot of space, you probably want to go with domes assembles, similar to the Cordoba mosque, with tension columns.  The lower domes can be filled with regolith and covered with a concrete layer.

If you have have automatic retrieval pallet based systems, you can probably do away with the columns and build a quasi spherical multi-storage assembly unit for the pallets.  This way you can first build the pressure vessel, then you can assemble a structure inside of it, in comfortable working conditions.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/07/2020 10:20 pm
Has anyone investigated duplex stainless steels, or their equivalent non rust proof steels, to reduce wall thickness and cost of the pressure vessels?  Cold rolled steels lose their advantage once welded.  So although cold rolled structural elements might be useful in some cases (tension beams, for example) they don't really save the designer much in practical usage.

I think duplex steels keep their properties when welded, so a reduction in mass of nearly 50% for the pressure envelopes of the settlements seems like an interesting gain.  The embodied energy of duplex steels is about the same as for standard steels, so from that point of view the used of duplex steels also seems advantageous.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/07/2020 10:28 pm
On Mars, due to the lower gravity, rings can be made much larger without deformation.  So we imagined something like the joined video, but on a much larger scale without being significantly heavier.

Could be done in the open, like a certain Starship we know...

https://www.youtube.com/watch?v=Mvz_-7we_4c
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/07/2020 10:32 pm
Has anyone investigated duplex stainless steels, or their equivalent non rust proof steels, to reduce wall thickness and cost of the pressure vessels?  Cold rolled steels lose their advantage once welded.  So although cold rolled structural elements might be useful in some cases (tension beams, for example) they don't really save the designer much in practical usage.

I think duplex steels keep their properties when welded, so a reduction in mass of nearly 50% for the pressure envelopes of the settlements seems like an interesting gain.  The embodied energy of duplex steels is about the same as for standard steels, so from that point of view the used of duplex steels also seems advantageous.

Our analysis uses basic Carbon Steel.
Why?
I don't want to have to find 200 tonnes of Chromium per habitat.

Mechanically, you can get very good (read:sufficent) performance out of Carbon Steel, with the only draw back being the lack of corrosion protection.

HOWEVER! If you are making these entirely out of Martial soil, you'll also get your hands on alot of Aluminium (which you may want to use elsewhere) and Magnesium, both of which make fantastic sacrifical anodes. Just make sure you replace them often enough.

Remember: Reduce cost is not the same as reducing materials, it takes alot more water and energy per kilogram to make steel than plastic.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/07/2020 11:22 pm
Pressure vessels have some interesting characteristics:
If you increase the diameter, you thicken the walls, but for the same interior volume the total amount of metal in the wall remains the same.  In other words, of you double the diameter you double the wall thickness, as it is a direct ratio.  But you also increase the volume to the square of the increase.  To get the same volume increase with your initial cylinder, you will need to make it longer by the square of the increase of the diameter.  So the amount of metal is the same for a large or a small cylinder, at the same pressure for the same total volume. 
This means that for a large settlement you may want to go with larger pressure vessels, to get better usage of the space.  The are construction issues, of course. that limit the size that is buildable.

This is true. However, note that if you're building a modular building as I have described (out of "merged" cylinders), you still get the same mass efficiency as one big cylinder with the same volume.

The pressure times the volume is equal to the energy in the pressure vessel.  In fact, 1Pa x 1m3 = 1joule.  So even if you subdivide the pressure vessel into a number of open cells, the overall energy contained by the structure will be the same, (pretty certain, but it's been a long time!) and eventually, the amount of material for fabrication will be the same.  It is just the shape that will change.

Bingo.

So there is no material gain in using compound lateral tanks with beams as far as material costs go.  There is only a gain in dimensions and accessibility in one dimension or two dimensions for the one or two dimensions system.

Right. But by the same token, there's no downside as far as material costs go.

The real gain is in improved volumetric utilization. Lower total volume for the same function translates to lower cost for the same function, regardless of whether the per-cubic-meter cost remains the same.

Another interesting element is that for a spherical shape, the strain in the wall is reduced by 50%.  So a truly spherical pressure vessel has thinner walls and is more cost effective.  However, architecturally the sphere is a pain to use.  Hence the cylinders.

So to create the cheapest volume of space for the settlement, spheres would be optimum as far as volume goes.  So it you are storing water, gases or similar fluid items, use spheres as much as possible.

Yeah, spheres are so tempting for that reason. With pre-fab (stamped steel?) modular panels, you could have identical spherical or near-spherical "arch" pieces that can function either as roof, walls, or floor panels.

All the same volumetric utilization advantages of prismatic layout, plus the mass advantage of spherical vessels. Essentially this would mean that all the I-beams in the entire 3D grid could be reduced in mass by ~half.

If you are storing cargo that needs to be accessible, single floor building are usually the best. To avoid wasting a lot of space, you probably want to go with domes assembles, similar to the Cordoba mosque, with tension columns.  The lower domes can be filled with regolith and covered with a concrete layer.

A structure geometrically similar to the Cordoba mosque (with straight columns extending below the arched volume) would need tension columns not just running vertically (Z axis), but also left/right and forward/back (X and Y axes) as well.

It seems we're both converging on essentially the same design space.

If you have have automatic retrieval pallet based systems, you can probably do away with the columns and build a quasi spherical multi-storage assembly unit for the pallets.  This way you can first build the pressure vessel, then you can assemble a structure inside of it, in comfortable working conditions.

High density pallet racks are great, but they're no panacea. You still have wasted volume in "awkward corners," and your retrieval robot with a certain X by Y by Z range has its usable volume truncated by the curved walls, reducing maximum storage capacity per robot. It also reduces your part commonality because you need more unique types of mounting brackets to attach the rack structure to different parts of the spherical walls.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/08/2020 01:57 am
Has anyone investigated duplex stainless steels, or their equivalent non rust proof steels, to reduce wall thickness and cost of the pressure vessels?  Cold rolled steels lose their advantage once welded.  So although cold rolled structural elements might be useful in some cases (tension beams, for example) they don't really save the designer much in practical usage.

I think duplex steels keep their properties when welded, so a reduction in mass of nearly 50% for the pressure envelopes of the settlements seems like an interesting gain.  The embodied energy of duplex steels is about the same as for standard steels, so from that point of view the used of duplex steels also seems advantageous.

Our analysis uses basic Carbon Steel.
Why?
I don't want to have to find 200 tonnes of Chromium per habitat.

Mechanically, you can get very good (read:sufficent) performance out of Carbon Steel, with the only draw back being the lack of corrosion protection.

HOWEVER! If you are making these entirely out of Martial soil, you'll also get your hands on alot of Aluminium (which you may want to use elsewhere) and Magnesium, both of which make fantastic sacrifical anodes. Just make sure you replace them often enough.

Remember: Reduce cost is not the same as reducing materials, it takes alot more water and energy per kilogram to make steel than plastic.
Very interesting!  I hadn't realized there was so much chrome in stainless steel.  Though it was mostly nickel.
As far as the energy required to make plastic, it's actually more energy intensive than steel on a kj/kg basis.

https://en.wikipedia.org/wiki/Embodied_energy

Perhaps chrome is not that hard to make, as stainless steel in not that much more energy intensive than steel?  But anyway, chromium steel seems like a complicated choice. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/08/2020 07:36 am
Has anyone investigated duplex stainless steels, or their equivalent non rust proof steels, to reduce wall thickness and cost of the pressure vessels?  Cold rolled steels lose their advantage once welded.  So although cold rolled structural elements might be useful in some cases (tension beams, for example) they don't really save the designer much in practical usage.

I think duplex steels keep their properties when welded, so a reduction in mass of nearly 50% for the pressure envelopes of the settlements seems like an interesting gain.  The embodied energy of duplex steels is about the same as for standard steels, so from that point of view the used of duplex steels also seems advantageous.

Our analysis uses basic Carbon Steel.
Why?
I don't want to have to find 200 tonnes of Chromium per habitat.

Mechanically, you can get very good (read:sufficent) performance out of Carbon Steel, with the only draw back being the lack of corrosion protection.

HOWEVER! If you are making these entirely out of Martial soil, you'll also get your hands on alot of Aluminium (which you may want to use elsewhere) and Magnesium, both of which make fantastic sacrifical anodes. Just make sure you replace them often enough.

Remember: Reduce cost is not the same as reducing materials, it takes alot more water and energy per kilogram to make steel than plastic.
Very interesting!  I hadn't realized there was so much chrome in stainless steel.  Though it was mostly nickel.
As far as the energy required to make plastic, it's actually more energy intensive than steel on a kj/kg basis.

https://en.wikipedia.org/wiki/Embodied_energy

Perhaps chrome is not that hard to make, as stainless steel in not that much more energy intensive than steel?  But anyway, chromium steel seems like a complicated choice.

It's not so much the energy requirments to get chromium and make stainless steel, it's more that if you want stainless steel, you need alot of chromium. Like I said, if you took our design of the Martian Colosseum, which has roughly 2,000 tonnes of steel, you would need at a minimum 200 tonne of Chromium (Stainless Steel is 10-15% chromium by weight, and also usually 8% by weight nickle).

Our main design goal was to just use Martian Air, Earth and Water as much as possible. Given the number of sites that have been tested directly, and the colour of the planet, its reasonable to assume that you can get Iron pretty much anywhere. The only question that could torpedo our design is how thick is the iron rich layer. Based on our calcualtions, we only need roughly a meter, and mining sites become a reasonable size.

Additionally, the real benefit of using plastic is that you can have thinner layers and thus less mass. I've not done a comparison in how thin you can make the layers V. energy to make. As I understand it, plastics take roughly 4 x as much energy to make than steels, and roughly 180L of water per kilogram. (citation needed)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/08/2020 07:51 am
Has anyone investigated duplex stainless steels, or their equivalent non rust proof steels, to reduce wall thickness and cost of the pressure vessels?  Cold rolled steels lose their advantage once welded.  So although cold rolled structural elements might be useful in some cases (tension beams, for example) they don't really save the designer much in practical usage.

I think duplex steels keep their properties when welded, so a reduction in mass of nearly 50% for the pressure envelopes of the settlements seems like an interesting gain.  The embodied energy of duplex steels is about the same as for standard steels, so from that point of view the used of duplex steels also seems advantageous.

Our analysis uses basic Carbon Steel.
Why?
I don't want to have to find 200 tonnes of Chromium per habitat.

Mechanically, you can get very good (read:sufficent) performance out of Carbon Steel, with the only draw back being the lack of corrosion protection.

HOWEVER! If you are making these entirely out of Martial soil, you'll also get your hands on alot of Aluminium (which you may want to use elsewhere) and Magnesium, both of which make fantastic sacrifical anodes. Just make sure you replace them often enough.

Remember: Reduce cost is not the same as reducing materials, it takes alot more water and energy per kilogram to make steel than plastic.
Very interesting!  I hadn't realized there was so much chrome in stainless steel.  Though it was mostly nickel.
As far as the energy required to make plastic, it's actually more energy intensive than steel on a kj/kg basis.

https://en.wikipedia.org/wiki/Embodied_energy

Perhaps chrome is not that hard to make, as stainless steel in not that much more energy intensive than steel?  But anyway, chromium steel seems like a complicated choice. 


Depends what kind of plastic. Polyethylene requires about 25kWh/kg (90MJ/kg) for something made directly from the Sabatier process. Propyelene is nearly twice as much due to the inherent inefficiency of the process (only about half the input becomes propyelene). Easily sourced, simple inputs: CO2, water and electricity. Very scalable, and about the best radiation shielding material available. It's transparent in thin sheets and translucent in somewhat thicker sheets: great for greenhouses. You'll want to use it as much as possible in interiors for the backstop effect anyway.

Mixed with glass fibre, 15MJ/kg, and you significantly increase strength whilst reducing energy input. At 50% you get something that is at least as strong by weight and the same or less energy cost to produce, for the requirement of having to produce glass. And it's also still a decent radiation stopper in thick sections and can be made fairly transparent in thin sections.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/08/2020 08:02 am
Has anyone investigated duplex stainless steels, or their equivalent non rust proof steels, to reduce wall thickness and cost of the pressure vessels?  Cold rolled steels lose their advantage once welded.  So although cold rolled structural elements might be useful in some cases (tension beams, for example) they don't really save the designer much in practical usage.

I think duplex steels keep their properties when welded, so a reduction in mass of nearly 50% for the pressure envelopes of the settlements seems like an interesting gain.  The embodied energy of duplex steels is about the same as for standard steels, so from that point of view the used of duplex steels also seems advantageous.

Our analysis uses basic Carbon Steel.
Why?
I don't want to have to find 200 tonnes of Chromium per habitat.

Mechanically, you can get very good (read:sufficent) performance out of Carbon Steel, with the only draw back being the lack of corrosion protection.

HOWEVER! If you are making these entirely out of Martial soil, you'll also get your hands on alot of Aluminium (which you may want to use elsewhere) and Magnesium, both of which make fantastic sacrifical anodes. Just make sure you replace them often enough.

Remember: Reduce cost is not the same as reducing materials, it takes alot more water and energy per kilogram to make steel than plastic.
Very interesting!  I hadn't realized there was so much chrome in stainless steel.  Though it was mostly nickel.
As far as the energy required to make plastic, it's actually more energy intensive than steel on a kj/kg basis.

https://en.wikipedia.org/wiki/Embodied_energy

Perhaps chrome is not that hard to make, as stainless steel in not that much more energy intensive than steel?  But anyway, chromium steel seems like a complicated choice. 


Depends what kind of plastic. Polyethylene requires about 25kWh/kg (90MJ/kg) for something made directly from the Sabatier process. Propyelene is nearly twice as much due to the inherent inefficiency of the process (only about half the input becomes propyelene). Easily sourced, simple inputs: CO2, water and electricity. Very scalable, and about the best radiation shielding material available. It's transparent in thin sheets and translucent in somewhat thicker sheets: great for greenhouses. You'll want to use it as much as possible in interiors for the backstop effect anyway.

Mixed with glass fibre, 15MJ/kg, and you significantly increase strength whilst reducing energy input. At 50% you get something that is at least as strong by weight and the same or less energy cost to produce, for the requirement of having to produce glass. And it's also still a decent radiation stopper in thick sections and can be made fairly transparent in thin sections.

And how does it fair for maintenance/repairs? And long term expsoure to elements/UV? And are those inputs water or hydrogen from electrolysis?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/08/2020 02:30 pm
And how does it fair for maintenance/repairs? And long term expsoure to UV?

Repairs: Presumably the same way fibreglass is normally repaired: by glue or patching. Although with the ability to 3D print it anyway, cut a hole and print a fresh section over it.

UV exposure: polymers on Earth primarily degrade because of photooxidation, and is accelerated by moisture and high temperatures.

The bad news is that UV-C is strong on Mars, and it provides lots of energy to break bonds. The good news is that most plastic strongly absorbs it in a few micrometres (except PE, because of its mostly C-C bonds). It might degrade, but you could replace it with another thin film. It's not going to suffer any oxygen degradation on the outside anyway - unlike being on Earth, where UV-C would very quickly destroy plastics in the presence of oxygen. So you're effectively dealing with UVA and UVB in the bulk of the plastic, because you don't want to kill people and plants, albeit at less than Earth intensities, and you want to minimise photooxidation on the pressurised side. UV-resistant additives are available in commercial plastics as an option. Acrylic and polycarbonate are very UV resistant, and are what I would suggest for scenic windows as opposed to letting light in. Polyester is also somewhat UV resistant, but is translucent.

For non-transparent applications out in the sun, carbon black is very effective and oh so cheap. It also makes HDPE conductive, and this can be used to heat the structure, up to melting point. Could have some applications for self-repair.

Regarding energy cost: I currently have a LOT of windows open, and I'm just trying to save the links I have. I was surprised at the source I found, expecting it to be more like 200MJ/kg. I will go back and look at the assumptions, I think they assume Sabatier process gives a lot of waste heat which can be captured to use in the rest of the process. For the other part, electrolysis efficiency assumptions vary a lot.

I've found (forum) sources that estimate up to eight times the per weight cost of steel. I just haven't been able to find a really authoritative estimate for the energy cost of PE.

Martian UV environment (at Gale Crater): https://www.researchgate.net/publication/316199127_Determination_of_dust_aerosol_particle_size_at_Gale_Crater_using_REMS_UVS_and_Mastcam_measurements
Very good NTRS report on polymers and UV degradation:
https://ntrs.nasa.gov/search.jsp?R=19780009276
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 07/08/2020 03:19 pm
I can identify the vertical tension members and how they work, but I can't comprehend the horizontal tension members. They seem "broken" in this diagram, and some of the lateral "domes" I would expect seem to be missing.

Flat exterior walls might be supported by a structure with sufficient bending strength, but I assume there's a good reason why terrestrial pressure vessels never use flat walls to separate pressurized and non-pressurized volumes (probably something about membrane structures (https://en.wikipedia.org/wiki/Membrane_structure)).
The internal volume all has the same pressure. Those internal walls keep no pressure back
The side walls actually work as a big girder the width of the whole wall (3m)
If you look close, you will see its not just columns, but there are structural elements to complete the girders.
Then there are tension rods to balance out the force on the opposing walls.

Hope the pic is clear
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/08/2020 05:32 pm
[snip]

Depends what kind of plastic. Polyethylene requires about 25kWh/kg (90MJ/kg) for something made directly from the Sabatier process. Propyelene is nearly twice as much due to the inherent inefficiency of the process (only about half the input becomes propyelene). Easily sourced, simple inputs: CO2, water and electricity. Very scalable, and about the best radiation shielding material available. It's transparent in thin sheets and translucent in somewhat thicker sheets: great for greenhouses. You'll want to use it as much as possible in interiors for the backstop effect anyway.

Just to make sure we're all on the same page, you mean propylene, right? I can't find a chemical named "propyelene," but then again I'm not a chemist.

https://en.wikipedia.org/wiki/Propene
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/09/2020 09:43 am
[snip]

Depends what kind of plastic. Polyethylene requires about 25kWh/kg (90MJ/kg) for something made directly from the Sabatier process. Propyelene is nearly twice as much due to the inherent inefficiency of the process (only about half the input becomes propyelene). Easily sourced, simple inputs: CO2, water and electricity. Very scalable, and about the best radiation shielding material available. It's transparent in thin sheets and translucent in somewhat thicker sheets: great for greenhouses. You'll want to use it as much as possible in interiors for the backstop effect anyway.

Just to make sure we're all on the same page, you mean propylene, right? I can't find a chemical named "propyelene," but then again I'm not a chemist.

https://en.wikipedia.org/wiki/Propene

Propene is another name for propylene, which is the monomer for polypropylene. I should have clarified that I'm referring to propylene polymers, aka polypropylene. The methyl groups in it make it worthless against UV rays though, although it has decent chemical resistance.

Anyway, (poly)propylene is kind of a waste product from fossil fuel cracking to get ethylene. You'd have to make it on purpose on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 07/09/2020 01:34 pm
Water filled glass assemblies.
First time I see these as a product, might be interesting results for Mars

https://www.sciencedirect.com/science/article/abs/pii/S0378778819328944?via=ihub

Energy consumption of water-filled glass (WFG) hybrid building envelope.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/10/2020 12:15 am
[snip]

Depends what kind of plastic. Polyethylene requires about 25kWh/kg (90MJ/kg) for something made directly from the Sabatier process. Propyelene is nearly twice as much due to the inherent inefficiency of the process (only about half the input becomes propyelene). Easily sourced, simple inputs: CO2, water and electricity. Very scalable, and about the best radiation shielding material available. It's transparent in thin sheets and translucent in somewhat thicker sheets: great for greenhouses. You'll want to use it as much as possible in interiors for the backstop effect anyway.

Just to make sure we're all on the same page, you mean propylene, right? I can't find a chemical named "propyelene," but then again I'm not a chemist.

https://en.wikipedia.org/wiki/Propene

Propene is another name for propylene, which is the monomer for polypropylene. I should have clarified that I'm referring to propylene polymers, aka polypropylene. The methyl groups in it make it worthless against UV rays though, although it has decent chemical resistance.

Anyway, (poly)propylene is kind of a waste product from fossil fuel cracking to get ethylene. You'd have to make it on purpose on Mars.

Yeah, Wikipedia redirected me, and I didn't bother editing the URL.

Good to know that propyelene was just a typo, not (yet another) yawning gap in my chemistry knowledge.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RotoSequence on 07/12/2020 08:17 am
My only thinking so far is that these lovely habitats would be quite difficult for early Martian colonists to build and inhabit; they'd either be tricky to assemble, difficult to use efficiently, or some other combination of difficult and awkward, and radiation shielding probably needs to fall into the realm of "good enough" for the early days. My thinking is that a simple trench at the angle of repose for martian soil can be filled with some analog of concrete, built up with form works for habitable space, and then buried under a few feet of martian soil for radiation protection. None of this quick and dirty sketchup work is optimized for anything by any stretch of the imagination, but the easier it is for whatever poor person has to do construction work in a pressure suit, the faster and more affordable it will be to create large amounts of living space for colonists.

I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs. I'm sure people who've put much more thought into this can find plenty of holes to poke in this minimally developed design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/12/2020 10:26 am
My only thinking so far is that these lovely habitats would be quite difficult for early Martian colonists to build and inhabit; they'd either be tricky to assemble, difficult to use efficiently, or some other combination of difficult and awkward, and radiation shielding probably needs to fall into the realm of "good enough" for the early days. My thinking is that a simple trench at the angle of repose for martian soil can be filled with some analog of concrete, built up with form works for habitable space, and then buried under a few feet of martian soil for radiation protection. None of this quick and dirty sketchup work is optimized for anything by any stretch of the imagination, but the easier it is for whatever poor person has to do construction work in a pressure suit, the faster and more affordable it will be to create large amounts of living space for colonists.

I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs. I'm sure people who've put much more thought into this can find plenty of holes to poke in this minimally developed design.

Looks great. My own personal view is that the simplest way to shield the habitats is simply dig trenches, drop them in and cover with a lot of dirt, or water if you have it. Here, you'd need to make the outer walls concave or convex to balance out the pressure, and some internal cables or other tensioning system to balance it out, easy enough to integrate.

A few more metres of radiation shielding on top would be good enough for pioneer astronaut types. I guess as a rule of thumb, you can go by this: 2m of concrete for "astronaut" level protection, 4m for "colonist" and 6m for children and pregnant women.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 07/12/2020 06:27 pm
I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs.

Why not also habitats and work space?

For larger underground areas I would add roadheaders to the TBMs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RotoSequence on 07/13/2020 03:39 am
I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs.

Why not also habitats and work space?

For larger underground areas I would add roadheaders to the TBMs.

The increased working area slows them down and makes them more expensive to operate, especially at "habitat" scale. Small TBMs don't need to be anything special if you're just trying to create a small pathway and a place to run conduit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/13/2020 08:56 am
My only thinking so far is that these lovely habitats would be quite difficult for early Martian colonists to build and inhabit; they'd either be tricky to assemble, difficult to use efficiently, or some other combination of difficult and awkward, and radiation shielding probably needs to fall into the realm of "good enough" for the early days. My thinking is that a simple trench at the angle of repose for martian soil can be filled with some analog of concrete, built up with form works for habitable space, and then buried under a few feet of martian soil for radiation protection. None of this quick and dirty sketchup work is optimized for anything by any stretch of the imagination, but the easier it is for whatever poor person has to do construction work in a pressure suit, the faster and more affordable it will be to create large amounts of living space for colonists.

I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs. I'm sure people who've put much more thought into this can find plenty of holes to poke in this minimally developed design.

Very cool, but quick question:
What is your internal pressure going to be? At 50,000 Pa, you need roughly 9m of piled regolith, 7m iif you compress it down to 2000 kg/m2.

Essentially if you're going to balance your inernal pressure with regolith, you've got more than enough for radiation sheilding.

Earth standard is ~ 101,320 Pa, so ~double the above numbers, and that is before you can START to build, so you need to go even deeper still. As a result, your minimum depth becomes ~15-20 meters.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/13/2020 07:58 pm
My only thinking so far is that these lovely habitats would be quite difficult for early Martian colonists to build and inhabit; they'd either be tricky to assemble, difficult to use efficiently, or some other combination of difficult and awkward, and radiation shielding probably needs to fall into the realm of "good enough" for the early days. My thinking is that a simple trench at the angle of repose for martian soil can be filled with some analog of concrete, built up with form works for habitable space, and then buried under a few feet of martian soil for radiation protection. None of this quick and dirty sketchup work is optimized for anything by any stretch of the imagination, but the easier it is for whatever poor person has to do construction work in a pressure suit, the faster and more affordable it will be to create large amounts of living space for colonists.

I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs. I'm sure people who've put much more thought into this can find plenty of holes to poke in this minimally developed design.

Looks great. My own personal view is that the simplest way to shield the habitats is simply dig trenches, drop them in and cover with a lot of dirt, or water if you have it. Here, you'd need to make the outer walls concave or convex to balance out the pressure, and some internal cables or other tensioning system to balance it out, easy enough to integrate.


A few more metres of radiation shielding on top would be good enough for pioneer astronaut types. I guess as a rule of thumb, you can go by this: 2m of concrete for "astronaut" level protection, 4m for "colonist" and 6m for children and pregnant women.

I notice that this geometry is still excavating a lot more regolith than what is actually needed for the shielding roof. And yes I'm assuming you start off with relatively flat terrain, since preexisting sloped terrain tends to be unstable.

If the internal pressure is restrained by a tension system and not the regolith pressure around you, there's no reason you need to set the habitat "flush" with the ground. You can still set it within a depression, but it only needs to be so deep that the excavation supplies enough material to cover it.

On the outer wall you can use an angle-of-repose slope (simple but requires moving lots of dirt), or you can use something like a mechanically stabilized earth wall (uses much less dirt, but you need reinforcing materials). The construction of MSE walls is very similar to HESCO bastions, so perhaps some intermediate "pre-fab" solution that's lightweight and reduced touch labor like HESCO bastions, but omits the in-between layers that aren't needed if you're just using the bastions like an MSE wall.

Naturally you can anchor the steel grid or geotextile to a false wall, all but eliminating the possibility of pull-out failure.


Naively I would expect angle of repose slopes to be favored for shielding early habs (since they can be constructed almost entirely by tele-operation), and mechanically stabilized shielding walls for later habs (to maximize city density which makes transport/infrastructure easier).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ice on 07/16/2020 04:28 pm
How SpaceX Mars Colony could look like in a few decades by Polish 3D artist Andrzej Pawelec (https://www.humanmars.net/2020/07/how-spacex-mars-colony-could-look-like.html)

A bunch of interesting drawings and a detailed animation there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 07/17/2020 01:02 pm
I notice that this geometry is still excavating a lot more regolith than what is actually needed for the shielding roof. And yes I'm assuming you start off with relatively flat terrain, since preexisting sloped terrain tends to be unstable.

If the internal pressure is restrained by a tension system and not the regolith pressure around you, there's no reason you need to set the habitat "flush" with the ground. You can still set it within a depression, but it only needs to be so deep that the excavation supplies enough material to cover it.

On the outer wall you can use an angle-of-repose slope (simple but requires moving lots of dirt), or you can use something like a mechanically stabilized earth wall (uses much less dirt, but you need reinforcing materials). The construction of MSE walls is very similar to HESCO bastions, so perhaps some intermediate "pre-fab" solution that's lightweight and reduced touch labor like HESCO bastions, but omits the in-between layers that aren't needed if you're just using the bastions like an MSE wall.

Naturally you can anchor the steel grid or geotextile to a false wall, all but eliminating the possibility of pull-out failure.


Naively I would expect angle of repose slopes to be favored for shielding early habs (since they can be constructed almost entirely by tele-operation), and mechanically stabilized shielding walls for later habs (to maximize city density which makes transport/infrastructure easier).

Regolith is really trivial to move around. A TLB can move around a huge amount of it before lunch. However, there are craters a-plenty on Mars to make a little village inside and cover over.
The thing to remember with pressure is that soil or rock pressure comes in as arches. It squeezes the sides of a tunnel - it does not press "down" on it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/17/2020 07:07 pm
I notice that this geometry is still excavating a lot more regolith than what is actually needed for the shielding roof. And yes I'm assuming you start off with relatively flat terrain, since preexisting sloped terrain tends to be unstable.

If the internal pressure is restrained by a tension system and not the regolith pressure around you, there's no reason you need to set the habitat "flush" with the ground. You can still set it within a depression, but it only needs to be so deep that the excavation supplies enough material to cover it.

On the outer wall you can use an angle-of-repose slope (simple but requires moving lots of dirt), or you can use something like a mechanically stabilized earth wall (uses much less dirt, but you need reinforcing materials). The construction of MSE walls is very similar to HESCO bastions, so perhaps some intermediate "pre-fab" solution that's lightweight and reduced touch labor like HESCO bastions, but omits the in-between layers that aren't needed if you're just using the bastions like an MSE wall.

Naturally you can anchor the steel grid or geotextile to a false wall, all but eliminating the possibility of pull-out failure.


Naively I would expect angle of repose slopes to be favored for shielding early habs (since they can be constructed almost entirely by tele-operation), and mechanically stabilized shielding walls for later habs (to maximize city density which makes transport/infrastructure easier).

Regolith is really trivial to move around. A TLB can move around a huge amount of it before lunch.

"Huge" compared to a shovel and wheelbarrow, sure. The problem is that an angle-of-repose slope gets really huge as the height increases. The volume of regolith moved scales as h3. Hence as you get higher, there's an increased desire for a stabilized vertical wall, where the volume scales as h. Naturally it's a trade-off, since reinforced walls are more expensive per-m3 than compacted regolith.


The thing to remember with pressure is that soil or rock pressure comes in as arches. It squeezes the sides of a tunnel - it does not press "down" on it.

Of course. But the earth pressure of the structure depicted would be far too low to counteract the internal atmospheric pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 07/20/2020 02:34 am
[Didn't notice this when posted. Probably off-topic, but I'm curious...]

Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.

Why does s/he think that settlements can't work with the existing treaty?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/20/2020 08:26 am
[Didn't notice this when posted. Probably off-topic, but I'm curious...]

Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.

Why does s/he think that settlements can't work with the existing treaty?

Small scale it's fine (fun fact: the Outer Space Treaty applies to the surface of a celestial body...but INSIDE a spacecraft like a station, or ship or even a space suit, you're stil beholden to the owning coutries laws, like Internation waters. So you can't claim land on a celestial body, but you CAN claim useful land I.E. somewhere some one can...you know... breath, because you'd have to make that)

Its more that too many issues can start to arise once you start getting, say 1,000,000 people and multiple cities/settlements. At that stage you would want to clarify/streamline things which may actually need to wait to that point so we can see what the problems are.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 07/20/2020 08:59 am
Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.
Why does s/he think that settlements can't work with the existing treaty?
fun fact: the Outer Space Treaty applies to the surface of a celestial body...but INSIDE a spacecraft like a station, or ship or even a space suit, you're stil beholden to the owning coutries laws, like Internation waters. So you can't claim land on a celestial body, but you CAN claim useful land I.E. somewhere some one can...you know... breath, because you'd have to make that

I knew that, which was why I asked the question. To me, OST has always felt like the best solution for exploitation, settlement, colonisation. Introducing anything similar to territorial claims would be a disaster.

Its more that too many issues can start to arise once you start getting, say 1,000,000 people and multiple cities/settlements. At that stage you would want to clarify/streamline things which may actually need to wait to that point so we can see what the problems are.

Still not seeing where OST would need to be changed. The non-interference clause lends itself to co-operation between settlements under different national jurisdiction (much moreso than actual territorial sovereignty would.) And those under the same jurisdiction don't have even that issue, since the registrar nation can impose legislation. Except...

It even allows a path to greater independence. If the initial registrar doesn't allow the colony to run itself, or forces rules on them they don't like, they can switch the settlement's registration to a new flag-of-convenience nation with lax rules. Lichtenstein has already positioned itself as a flag-of-convenience nation for asteroid-mining. Others will inevitably pop up for settlements.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 07/20/2020 10:03 am
My thinking is that a simple trench at the angle of repose for martian soil can be filled with some analog of concrete, built up with form works for habitable space, and then buried under a few feet of martian soil for radiation protection.

Assuming the trench is being dug, then you've got vastly more excavated material than you are using as shielding, so why not use it all? It's there.

I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs.

On Earth at least, cut'n'cover is cheaper for greenfield construction. You only resort to tunnelling when you have to pass through mountains or under existing infrastructure. Whatever you use to dig your trench, dig an extra bit for the plumbing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lotick on 07/20/2020 12:50 pm
[Didn't notice this when posted. Probably off-topic, but I'm curious...]

Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.

Why does s/he think that settlements can't work with the existing treaty?

Small scale it's fine (fun fact: the Outer Space Treaty applies to the surface of a celestial body...but INSIDE a spacecraft like a station, or ship or even a space suit, you're stil beholden to the owning coutries laws, like Internation waters. So you can't claim land on a celestial body, but you CAN claim useful land I.E. somewhere some one can...you know... breath, because you'd have to make that)

Its more that too many issues can start to arise once you start getting, say 1,000,000 people and multiple cities/settlements. At that stage you would want to clarify/streamline things which may actually need to wait to that point so we can see what the problems are.

We can see how territorial claims are difficult to resolve here on earth, in Antarctica. A actually believe that 'colonization' of Antarctica is a good model for Mars colonization. The first base was established more than a hundred years ago, yet all we see by now are few scientific bases in there and a lot of territorial claims. Likewise on Mars colonization would not be a fast process and most likely for a few hundred years would be driven mainly by science-oriented purposes. For such a long period of time, the political situation on earth can change dramatically, maybe the earth by itself would be ruled by one global government, or OST would be gone or replaced by new one. Too much space for speculation...

So let's stick to the topic, and talk about technical aspects of the base construction this is more realistic.  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 07/20/2020 07:54 pm
Also our Space Lawyer had some really good points on how to modify the Outer Space Treaty to make settlement work.
Why does s/he think that settlements can't work with the existing treaty?
fun fact: the Outer Space Treaty applies to the surface of a celestial body...but INSIDE a spacecraft like a station, or ship or even a space suit, you're stil beholden to the owning coutries laws, like Internation waters. So you can't claim land on a celestial body, but you CAN claim useful land I.E. somewhere some one can...you know... breath, because you'd have to make that

I knew that, which was why I asked the question. To me, OST has always felt like the best solution for exploitation, settlement, colonisation. Introducing anything similar to territorial claims would be a disaster.

Its more that too many issues can start to arise once you start getting, say 1,000,000 people and multiple cities/settlements. At that stage you would want to clarify/streamline things which may actually need to wait to that point so we can see what the problems are.

Still not seeing where OST would need to be changed. The non-interference clause lends itself to co-operation between settlements under different national jurisdiction (much moreso than actual territorial sovereignty would.) And those under the same jurisdiction don't have even that issue, since the registrar nation can impose legislation. Except...

It even allows a path to greater independence. If the initial registrar doesn't allow the colony to run itself, or forces rules on them they don't like, they can switch the settlement's registration to a new flag-of-convenience nation with lax rules. Lichtenstein has already positioned itself as a flag-of-convenience nation for asteroid-mining. Others will inevitably pop up for settlements.

I think you mean Luxembourg.

And the point is less what you can do with it, but what you can do CLEARLY.

No one is going to invest in a city if they know someone else can swoop in and take their stuff.
It's more that clarity and conflict resolution is required, rather than changes to the actual law, and that may not happen until we are actually there. Those would still be changes to the law, even if the writen word doesn't change. The change to the interpretation is ust as meaningful.

And one can't just change their Flag-of-Convenience at will. The colony might not like the rules they're under, but they may not get a say if all the influential people are back on Earth.

Slightly-off-topic-rant/
 That having been said, any this talk of 'Martian independence' right now is asinine. There won'tbe any talk of Martian Indepenance until a) we know humans can even be born and safely grow to maturity in 0.38g and b) Mars has a chance of producing everything it needs by itself and c) the Powers-that-Be back home haven't learned from 200 years of collapsing Empires.
/Slightly-off-topic-rant End
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/20/2020 09:01 pm
My thinking is that a simple trench at the angle of repose for martian soil can be filled with some analog of concrete, built up with form works for habitable space, and then buried under a few feet of martian soil for radiation protection.

Assuming the trench is being dug, then you've got vastly more excavated material than you are using as shielding, so why not use it all? It's there.

The problem comes when you assume "the trench" (as depicted) is being dug. But that's exactly where the overspending happens.

Instead, you can excavate a shallower hole and reduce the total cost of the construction project.

I haven't put a ton of thought into utility infrastructure, but I imagine specialized facilities for everything from sewage to transportation lines could be dug with TBMs.

On Earth at least, cut'n'cover is cheaper for greenfield construction. You only resort to tunnelling when you have to pass through mountains or under existing infrastructure. Whatever you use to dig your trench, dig an extra bit for the plumbing.

The phrase "cut and cover" typically comes with the unstated assumption that you want the final structure to be level with the pre-existing terrain. There is no such constraint for this project, so there's an opportunity to build it cheaper than either option.

As a real-world example, during WWII the Germans built above-ground "bunkers," being cheaper than underground construction. https://en.wikipedia.org/wiki/Air_raid_shelter#Hochbunker
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 07/21/2020 05:58 am
I think you mean Luxembourg.

(Damn it.) Yes, that one.

[I'll also add that I underplayed their involvement. They didn't just create a legal framework, they also invested (and lost) money with Planetary Resources.]

And one can't just change their Flag-of-Convenience at will.

Tell that to ship owners.

No one is going to invest in a city if they know someone else can swoop in and take their stuff.

And that's the FUD that I object to. Ownership rights are well established in space under OST. No-one can steal your stuff (except your own nation). To a degree that there aren't even salvage rights for clearly abandoned equipment or rubbish. (The only debatable area, IMO, is ownership of tailings and minimally improved tracks/landing-areas. And even here, I suspect the issue will be that the ownership rights will be too strong.)

I see the claim that there's uncertainty as being a self-fulfilling prophesy. It's the people claiming there's uncertainty who are creating it.

[Anyway, this is not an "amazing" topic. So...]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 07/21/2020 06:00 am
The phrase "cut and cover" typically comes with the unstated assumption that you want the final structure to be level with the pre-existing terrain.

I think in a thread like this, we can assume people are using terms in a loose way unless they clearly indicate otherwise. Otherwise we spend more time arguing over definitions that ideas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/21/2020 09:22 pm
The phrase "cut and cover" typically comes with the unstated assumption that you want the final structure to be level with the pre-existing terrain.

I think in a thread like this, we can assume people are using terms in a loose way unless they clearly indicate otherwise. Otherwise we spend more time arguing over definitions that ideas.

I dunno, it seems like "loose" definitions are likely to cause more confusion and noise, imo.

In this case, the paragraph mentioning "cut and cover" was actually apropos of something else (utility trenches). But in their post, they made it clear that they were assuming that the structure must be level with the ground, and then using that assumption to argue in favor of over-engineering parts of the design...

Assuming the trench is being dug, then you've got vastly more excavated material than you are using as shielding, so why not use it all? It's there.

...which is why I brought it up. ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 07/22/2020 12:30 am
Just to expand on the preceding point a little...

ISTM that habs can be divided into roughly two different "regimes,"

- truly underground habs, where the strength of the surrounding material support the tension of the internal atmosphere, and

- regolith-covered habs, where the atmospheric pressure tension is held by some secondary structure (steel, kevlar, aluminum, etc).

For underground habs, you're going to need to perform a geologic survey to ensure a safe structure, and bury it relatively deep. For very deep structures (>15-30 m, depending on bulk density), the earth pressure is sufficient to completely counteract the internal pressure, so the surrounding material remains entirely in compression not tension. This should improve reliability greatly. allowing construction in less stable geology.

For covered habs, the optimum slab shield depth is likely to be on the order of 1-3 meters thick (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JE006246). So we're looking at a relatively shallow burial depth.

Essentially your habs will either be really shallow or really deep, depending on the aforementioned design regime. Something in the middle doesn't seem to make a whole lot of sense. You wind up with a "depth gap."

To cross that gap, I would expect to see vertical tube structures, which connect buried surface structures to underground habs. For safety these should have sufficient tensile strength to restrain the internal pressure, avoiding structural reliance on (potentially unstable) shallow geology.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 07/22/2020 10:39 pm
How SpaceX Mars Colony could look like in a few decades by Polish 3D artist Andrzej Pawelec (https://www.humanmars.net/2020/07/how-spacex-mars-colony-could-look-like.html)

A bunch of interesting drawings and a detailed animation there.

Little did I realise to which extent the future Mars base will look like a 2003 computer game. Half:Life vibe!

But, holy moley, great production value on that video. Well done!
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 08/23/2020 04:11 am
For underground habs, you're going to need to perform a geologic survey to ensure a safe structure, and bury it relatively deep. For very deep structures (>15-30 m, depending on bulk density), the earth pressure is sufficient to completely counteract the internal pressure, so the surrounding material remains entirely in compression not tension. This should improve reliability greatly. allowing construction in less stable geology.

Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load.  Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

Loads are MPa, vs. air pressure kPa, so air pressure doesn't compensate.

Or carve hard basalt, very slowly with massive machinery; but surface habs make far more sense.  Ice habs (https://forum.nasaspaceflight.com/index.php?topic=48732.msg1989734#msg1989734), too -- new world, new tricks.

Image:  Sandstone uniaxial compressive strength vs. porosity.  Jizba 1992.  Mars porosity ~ 0.4. 

Refs.

Jizba, D.L., 1992. Mechanical and acoustical properties of sandstones and shales.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/23/2020 10:07 pm
LMT, could tunnelling work in typical Martian sandstone without having to resort to internal support?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 08/23/2020 11:14 pm
Another issue for all Martian habitats is water ice. The base will need to be situated near a large source of water ice for ISRU propellant manufacture. The operative word being "near". Ideally you want a huge amount of ice nearby but an area that is much more solid and ice free to build the base on. How easy will it be to find this combination before landing?

It would not be good to build on or near Martian ice as its exact composition and characteristics are not properly understood yet. There may be frozen brines, cathrates and a range of particulate contamination at different depths. Building below the surface of such material would also be potentially problematic as escaping heat from the habitat might destabilise these materials causing the formation of voids due to evaporation or sublimation and result in shifts in the ground structure around the base.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 08/23/2020 11:51 pm
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical. According to the chart you posted, even a weak 20% porosity gives >20Mpa strength.

(Your reference to "cut-and-cover" makes no sense, since in that situation, the overburden is assumed to provide no strength. Indeed, the cut'n'cover discussions assume loose regolith. Even when discussing sintered blocks or similar, it's only for convenience of handling and maintenance.)

Loads are MPa, vs. air pressure kPa, so air pressure doesn't compensate.

This is also backwards. The "load" on a shallow tunnel is atmospheric pressure, the "strength" is that required to prevent blow-out. Anything about 0.1MPa is capable of retaining the upward force of 1atm contained pressure, even ignoring the added downward force of the stone's weight.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 08/24/2020 12:46 am
For underground habs, you're going to need to perform a geologic survey to ensure a safe structure, and bury it relatively deep. For very deep structures (>15-30 m, depending on bulk density), the earth pressure is sufficient to completely counteract the internal pressure, so the surrounding material remains entirely in compression not tension. This should improve reliability greatly. allowing construction in less stable geology.

Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load.

Indeed, that's exactly what I was assuming. At 15-30 m depth (depending on density) you're no longer relying on strength of the rock, but only on the surrounding earth pressure (regolith pressure?).

Loads are MPa, vs. air pressure kPa, so air pressure doesn't compensate.

Regolith pressure increases with depth, so you just have to go deep enough. On Mars that's typically 15-30 m, depending on density. For instance in your linked example (a 2 tonne/m3 sandstone with 40% porosity) the required depth would be 22 m deep.

I do think we've discovered an architectural "depth gap" on Mars. Really shallow structures make good economic sense (regolith-covered), so too do really deep structures (regolith pressure restrained), but building at a depth "somewhere in a middle" winds up being more expensive than either one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 08/24/2020 01:33 am
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.

Image:  Bourke et al. 2019.  Fig. 11.10.  Image of etched sandstone taken by the Mastcam on the Curiosity Rover at Gale crater. Source: NASA/JPL-Caltech/MSSS.

Refs.

Bourke, M.C., Balme, M., Lewis, S., Lorenz, R.D. and Parteli, E., 2019. Planetary Aeolian Geomorphology. (http://www.tara.tcd.ie/bitstream/handle/2262/90841/Bourke28.pdf?sequence=1&isAllowed=y) Aeolian Geomorphology: A New Introduction, pp.261-286.

Coneybeare, C. E. B. "Influence of compaction on stratigraphic analyses." Bulletin of Canadian Petroleum Geology 15, no. 3 (1967): 331-345.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 08/24/2020 03:51 am
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.
...
You just attempted to shift the burden of proof. No. *you* find an example of Mars sandstone being 40% porosity. It doesn't fit with observations.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 08/24/2020 12:07 pm
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.
...

You just attempted to shift the burden of proof. No. *you* find an example of Mars sandstone being 40% porosity. It doesn't fit with observations.

I showed it four years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859).  You were there (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1611007#msg1611007).  You had no observations. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 08/25/2020 03:31 am
Another issue for all Martian habitats is water ice. The base will need to be situated near a large source of water ice for ISRU propellant manufacture. The operative word being "near". Ideally you want a huge amount of ice nearby but an area that is much more solid and ice free to build the base on. How easy will it be to find this combination before landing?

It would not be good to build on or near Martian ice as its exact composition and characteristics are not properly understood yet. There may be frozen brines, cathrates and a range of particulate contamination at different depths. Building below the surface of such material would also be potentially problematic as escaping heat from the habitat might destabilise these materials causing the formation of voids due to evaporation or sublimation and result in shifts in the ground structure around the base.

SpaceX is targeting ice-rich regions; you'd expect some ice in sediments near the base's big ice deposit.  Salts, too.  Notional cut-and-cover spaces, tunnels, and other warm excavations would likely encounter hygroscopic salt seepage; e.g., sulfate or perchlorate seeps (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1608175#msg1608175) in contact with hab structures.  The necessary humidity of hab air could also contribute to brine formation.

Surface structures avoid that chemical mess.  Glacier habs (https://forum.nasaspaceflight.com/index.php?topic=48732.msg1989734#msg1989734), too:  salt concentration is very low in glacier ice, due to the source.

Temperature must be controlled in a glacier hab, regardless.  Camp Century demonstrated successful methods.  Which of those methods, and what other methods, might be useful in, say, the Phlegra Montes glacier (https://forum.nasaspaceflight.com/index.php?topic=45762.msg1988091#msg1988091)?

Image:  Curiosity's powered-descent landing ellipse, 20 x 7 km, roughly overlaid on the big Phlegra Montes glacier.  Source image:  High Resolution Stereo Camera (HRSC), Mars Express / German Aerospace Center / Freie Universität Berlin.


https://www.youtube.com/watch?v=QvX0EryfAvU

Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 08/25/2020 09:01 am
Another issue for all Martian habitats is water ice. The base will need to be situated near a large source of water ice for ISRU propellant manufacture. The operative word being "near". Ideally you want a huge amount of ice nearby but an area that is much more solid and ice free to build the base on. How easy will it be to find this combination before landing?

It would not be good to build on or near Martian ice as its exact composition and characteristics are not properly understood yet. There may be frozen brines, cathrates and a range of particulate contamination at different depths. Building below the surface of such material would also be potentially problematic as escaping heat from the habitat might destabilise these materials causing the formation of voids due to evaporation or sublimation and result in shifts in the ground structure around the base.

SpaceX is targeting ice-rich regions; you'd expect some ice in sediments near the base's big ice deposit.  Salts, too.  Notional cut-and-cover spaces, tunnels, and other warm excavations would likely encounter hygroscopic salt seepage; e.g., sulfate or perchlorate seeps (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1608175#msg1608175) in contact with hab structures.  The necessary humidity of hab air could also contribute to brine formation.

Surface structures avoid that chemical mess.  Glacier habs (https://forum.nasaspaceflight.com/index.php?topic=48732.msg1989734#msg1989734), too:  salt concentration is very low in glacier ice, due to the source.

Temperature must be controlled in a glacier hab, regardless.  Camp Century demonstrated successful methods.  Which of those methods, and what other methods, might be useful in, say, the Phlegra Montes glacier (https://forum.nasaspaceflight.com/index.php?topic=45762.msg1988091#msg1988091)?

Image:  Curiosity's powered-descent landing ellipse, 20 x 7 km, roughly overlaid on the big Phlegra Montes glacier.  Source image:  High Resolution Stereo Camera (HRSC), Mars Express / German Aerospace Center / Freie Universität Berlin.


https://www.youtube.com/watch?v=QvX0EryfAvU
The salt concentration is very low in glacier ice on Earth, due to the source. But what about Mars? Were to processes that formed glaciers on Earth the same as the processes that formed glaciers on Mars? How certain are we of this? What about all the perchlorate laden debris and the propensity for rocks to sink into glaciers? What about the different gravity, different temperature range and different atmospheric pressure and composition?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 08/25/2020 04:30 pm
Another issue for all Martian habitats is water ice. The base will need to be situated near a large source of water ice for ISRU propellant manufacture. The operative word being "near". Ideally you want a huge amount of ice nearby but an area that is much more solid and ice free to build the base on. How easy will it be to find this combination before landing?

It would not be good to build on or near Martian ice as its exact composition and characteristics are not properly understood yet. There may be frozen brines, cathrates and a range of particulate contamination at different depths. Building below the surface of such material would also be potentially problematic as escaping heat from the habitat might destabilise these materials causing the formation of voids due to evaporation or sublimation and result in shifts in the ground structure around the base.

SpaceX is targeting ice-rich regions; you'd expect some ice in sediments near the base's big ice deposit.  Salts, too.  Notional cut-and-cover spaces, tunnels, and other warm excavations would likely encounter hygroscopic salt seepage; e.g., sulfate or perchlorate seeps (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1608175#msg1608175) in contact with hab structures.  The necessary humidity of hab air could also contribute to brine formation.

Surface structures avoid that chemical mess.  Glacier habs (https://forum.nasaspaceflight.com/index.php?topic=48732.msg1989734#msg1989734), too:  salt concentration is very low in glacier ice, due to the source.

Temperature must be controlled in a glacier hab, regardless.  Camp Century demonstrated successful methods.  Which of those methods, and what other methods, might be useful in, say, the Phlegra Montes glacier (https://forum.nasaspaceflight.com/index.php?topic=45762.msg1988091#msg1988091)?

Image:  Curiosity's powered-descent landing ellipse, 20 x 7 km, roughly overlaid on the big Phlegra Montes glacier.  Source image:  High Resolution Stereo Camera (HRSC), Mars Express / German Aerospace Center / Freie Universität Berlin.


https://www.youtube.com/watch?v=QvX0EryfAvU
The salt concentration is very low in glacier ice on Earth, due to the source. But what about Mars? Were to processes that formed glaciers on Earth the same as the processes that formed glaciers on Mars? How certain are we of this? What about all the perchlorate laden debris and the propensity for rocks to sink into glaciers? What about the different gravity, different temperature range and different atmospheric pressure and composition?

Clouds aren't salty, even on Mars.

Glacier pores seal quickly.  Thereafter any contamination is superficial:  e.g., dust cover possibly less than 4 m thick (https://forum.nasaspaceflight.com/index.php?topic=49532.msg2049972#msg2049972) on Phlegra Montes glacier. 

Cover that thin a Starship could likely spiral-sweep clear (https://forum.nasaspaceflight.com/index.php?topic=49532.msg2046874#msg2046874).  What's more, the first cargo ships could conceivably sweep out ice pads for future crewed ships, before diverting nearby to clear pads for themselves.

Immersion heaters (https://forum.nasaspaceflight.com/index.php?topic=44508.msg1933999#msg1933999) would make fast work of glacier excavation.  How might you seal (https://forum.nasaspaceflight.com/index.php?topic=45762.msg1989678#msg1989678) glacier silos, ramps, etc.?


https://www.youtube.com/watch?v=DFP4xl0V0mk
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 08/25/2020 08:50 pm
How SpaceX Mars Colony could look like in a few decades by Polish 3D artist Andrzej Pawelec (https://www.humanmars.net/2020/07/how-spacex-mars-colony-could-look-like.html)

A bunch of interesting drawings and a detailed animation there.

Little did I realise to which extent the future Mars base will look like a 2003 computer game. Half:Life vibe!

But, holy moley, great production value on that video. Well done!

I loved that vid a LOT, thanks for the find... very "the Expanse" vibe to it. Older model starships but a lot of it was like... this guy's been reading our ideas... :) (which is awesome)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 08/25/2020 08:57 pm
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.
...

You just attempted to shift the burden of proof. No. *you* find an example of Mars sandstone being 40% porosity. It doesn't fit with observations.

I showed it four years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859).  You were there (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1611007#msg1611007).  You had no observations. 

(mod)
I went and looked at the referenced post. It had  a graph but no easy to follow sources I could find at a quick glance. LMT, you have been warned about your dismissive and abrasive attitude before. You were better for a while but have returned to form, apparently.

Please provide the actual source for this 40% porosity claim, with a link that can be followed.

(fan) I myself find it hard to understand how we could KNOW porosity in advance given what I know of sampling and surveying carried out so far, but I'm open to convincing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 08/26/2020 06:30 am
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.
...

You just attempted to shift the burden of proof. No. *you* find an example of Mars sandstone being 40% porosity. It doesn't fit with observations.

I showed it four years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859).  You were there (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1611007#msg1611007).  You had no observations. 

(mod)
I went and looked at the referenced post. It had  a graph but no easy to follow sources I could find at a quick glance. LMT, you have been warned about your dismissive and abrasive attitude before. You were better for a while but have returned to form, apparently.

Please provide the actual source for this 40% porosity claim, with a link that can be followed.

(fan) I myself find it hard to understand how we could KNOW porosity in advance given what I know of sampling and surveying carried out so far, but I'm open to convincing.

?  The old post (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859) and the new post (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2123332#msg2123332) give reasoning and reference info.  It's uncontroversial thinking.  Plus sandstone's visible fragility (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2123608#msg2123608) matches reasoned UCS, just as TI / density / porosity relations indicate.  That's plenty of "actual source", in casual forum. 

Robotbeat made a false accusation backed by nonexistent observations (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2123725#msg2123725). 

Address that first, Lar, and you'll pop some groupthink on this topic.

Edit/Lar: I could swear you are arguing with mods. It was worse before the edits you did, but it's still there. Don't do that. If you have an issue, use the report to mod function. As you've been counseled before. And try to be less snarky and superior sounding. As you've been counseled before.  Straighten up and fly right or fly somewhere else. And don't remove this edit either.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 08/26/2020 07:23 am
2000 NIAC Research Report:  Development of Self-Sustaining Mars Colonies Utilizing the North Polar Cap and the Martian Atmosphere

In 2000, Plus Ultra Technologies completed a report (http://www.niac.usra.edu/files/studies/final_report/424Powell.pdf) on Mars colonies under the north polar cap.  The report details many aspects of a conceptual facility.

Nuclear power was required and estimated, with a team of 6 reactors producing 12 MW electrical and 60 MW thermal for a 500-man colony. 

The recent discovery of remnant glacial and crater-fill ice in mid-latitudes has improved the construction case.  At mid-latitudes PV farms and energy storage methods could plausibly get their 500-man facility through the winter without nuclear power; though reactors might still be required for non-stop, high-volume manufacturing centers.

Image:  Powell et al. 2000.  Figure 4.2.3.  "Top View of Angled Branch Configuration."  "Figure 4.2.3 shows a top view of the angled branched configuration, with the cavities azimuthally spaced around the lander."

Image:  Powell et al. 2000.  Figure 4.2.6.  "Melt Rate for Sub-Surface ALPH Cylindrical Cavities in Ice."  "Figure 4.2.6 shows the diameter of the cavity as a function of time after the melt balloon begins to operate, for heat fluxes of 0.05 and 0.10 watts per cm2 at the surface of the balloon.  To create a 10 meter diameter cavity at 0.1 watts per cm2 would take approximately 27 days; at 0.05 watts per cm2, it would take twice as long, or about 54 days.  The corresponding maximum thermal power (i.e., the thermal power required at the end of the cavity forming process) is ~500 kilowatts for 0.1 watts per cm2 heat flux, and ~250 kilowatts at 0.05 watts per cm2...  Accordingly, a 2.7 MW(th) ALPH reactor with a thermal waste heat output of 2.1 MW could form 8 such cavities (i.e., 10 meters in diameter and 15 meters long), in about a month."

Image:  Powell et al. 2000.  Figure 4.2.7.  "Warm Inflated Balloon Design Types."  "Figure 4.2.7 shows the construction of the melt/thermal insulation balloon.  The final shape and size are determined by the dimensions of the fine mesh net bag that encloses the actual balloon.  The strands of the net bag are assumed to be made of Spectra, a high strength drawn polyethylene fiber..."

Refs.

Powell, J., Maise, G., Paniagua, J. and Powell, J.R., 2000. Development of Self-Sustaining Mars Colonies Utilizing the North Polar Cap and the Martian Atmosphere. (http://www.niac.usra.edu/files/studies/final_report/424Powell.pdf) Final Report, NIAC Research Grant, pp.07600-053.
Title: Re: Envisioning Amazing Martian Habitats
Post by: FutureSpaceTourist on 08/26/2020 07:23 am
twitter.com/owensparks_/status/1298452185232089089

Quote
Would starship be able to lay down on the surface of moon / mars to make a permanent habitat if needed? Linear seems better than vertical for long term use.

https://twitter.com/elonmusk/status/1298452372704894979

Quote
No
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 08/26/2020 06:29 pm
twitter.com/owensparks_/status/1298452185232089089

Quote
Would starship be able to lay down on the surface of moon / mars to make a permanent habitat if needed? Linear seems better than vertical for long term use.

https://twitter.com/elonmusk/status/1298452372704894979

Quote
No

I suspect Jim has a new job posting Tweets for Elon
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 08/27/2020 04:47 am
twitter.com/owensparks_/status/1298452185232089089

Quote
Would starship be able to lay down on the surface of moon / mars to make a permanent habitat if needed? Linear seems better than vertical for long term use.

https://twitter.com/elonmusk/status/1298452372704894979

Quote
No

Good to have that quite preposterous notion shot down.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 08/27/2020 11:49 am
Earth rock is not Mars rock: porosity is only part of the story. Secondary porosity in rocks at Endurance crater range from 30%-42%. The sedimentary formations sampled with the RAT have generally ranged in UCS from 5-40MPA, which is fairly weak, comparable to calcrete. However, this is exposed, weathered rock, not rock beneath the overburden. Drilling stable tunnels would probably require some mix of grouting, umbrella arches, rock bolts, and shotcrete/concrete liners. The usual considerations for weak rock, but even <5 MPa UCS can be dealt with.

Sources:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL075965 (Fig 1)

https://www.researchgate.net/publication/228954505_Outcrop-scale_physical_properties_of_Burns_Formation_at_Meridiani_Planum_Mars

http://www.lpi.usra.edu/meetings/7thmars2007/pdf/3298.pdf (Fig 2)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 09/01/2020 11:43 am
Semi-finalists announced!
https://www.marssociety.org/news/2020/08/31/semi-finalists-chosen-for-mars-city-state-design-contest/

Who else here made the cut? :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/02/2020 03:32 am
Earth rock is not Mars rock: porosity is only part of the story. Secondary porosity in rocks at Endurance crater range from 30%-42%.

?  Secondary porosity occurs on Earth, too, as your reference Perl et al. 2007 noted:  "such values are not unusual in terrestrial sedimentary rocks..."

I'd ballparked ~ 40% porosity in Gale Crater sandstone; sounds about right, yes?  The primary / secondary distinction doesn't matter, for UCS ballpark.  (But see below re: deep excavation.)

The sedimentary formations [at Gale Crater] sampled with the RAT have generally ranged in UCS from 5-40MPA, which is fairly weak, comparable to calcrete.

Caliche isn't something you want your rock to be comparable to, when attempting multistory excavations that endure Mag 4+ Starship launch quakes.

Quote from: Peters et al. 2017
The weakest rocks at Gale are no stronger than adobe bricks (1.5–5 MPa)..., and the strongest rocks drilled can be compared to the strength of a standard concrete sidewalk or driveway (15–30 MPa)... The Murry and Stimson are composed of relatively weak rocks when compared to quartz‐indurated sandstones and siltstones found on Earth. As such, Murray and Stimson outcrops are more akin to geologically immature, terrestrial sandstones, and siltstones.

Their strongest rock was not sandstone, but a clay mudrock, fwiw; thoroughly fractured.

Image:  "Curiosity's Arm Over 'Marimba' Target on Mount Sharp."  NASA/JPL-Caltech/MSSS. 

However, this is exposed, weathered rock, not rock beneath the overburden.

Gale Crater rocks were exposed in the recent geological past, and the dry air hasn't altered them much.  So they should be representative.

Also, note the increase in secondary porosity with depth.  Opportunity observed an increase in spherule volume (hence secondary porosity) with depth at Meridiani; volume growing from 0.14 mm3 to 58 mm3 over a 27 m drop.  Squyres et al. 2009.  Deep excavations could be more porous, and weaker, at depth.

Image:  Squyres et al. 2009, Fig. 2.

Drilling stable tunnels would probably require some mix of grouting, umbrella arches, rock bolts, and shotcrete/concrete liners. The usual considerations for weak rock, but even <5 MPa UCS can be dealt with.

Yes, it "can be dealt with", theoretically, but the point of hab excavation was to use competent rock as load-bearing hab structure.  If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.  Those habs would be easier to heat, also.

--

I went and looked at the referenced post. It had  a graph but no easy to follow sources I could find at a quick glance.

Thoughts? 

--

Refs.

Perl, S.M., McLennan, S.M., Grotzinger, J.P. and Herkenhoff, K.E., 2007. Sedimentological Constraints on an Infiltrating Paleowater Table in the Burns Formation, Meridiani Planum, Mars. (https://www.lpi.usra.edu/meetings/7thmars2007/pdf/3298.pdf) LPICo, 1353, p.3298.

Peters, G.H., Carey, E.M., Anderson, R.C., Abbey, W.J., Kinnett, R., Watkins, J.A., Schemel, M., Lashore, M.O., Chasek, M.D., Green, W. and Beegle, L.W., 2018. Uniaxial compressive strengths of rocks drilled at Gale Crater, Mars. (https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL075965) Geophysical Research Letters, 45(1), pp.108-116.

Squyres, S.W., Knoll, A.H., Arvidson, R.E., Ashley, J.W., Bell, J.F., Calvin, W.M., Christensen, P.R., Clark, B.C., Cohen, B.A., De Souza, P.A. and Edgar, L., 2009. Exploration of Victoria crater by the Mars rover Opportunity. (https://dash.harvard.edu/bitstream/handle/1/3934552/Knoll_ExplorationVictoria2009.pdf?sequence=2&isAllowed=y) Science, 324(5930), pp.1058-1061.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/02/2020 03:41 am
If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.

Supporting this claim requires numerical comparison, not just hand-waving.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/02/2020 03:59 am
If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.

Supporting this claim requires numerical comparison, not just hand-waving.

No, just contrast the difficulty of constructing metal pressurized facilities in a fragile martian excavation, with that of dropping canisters onto the surface.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 09/02/2020 05:57 am
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.
...

You just attempted to shift the burden of proof. No. *you* find an example of Mars sandstone being 40% porosity. It doesn't fit with observations.

I showed it four years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859).  You were there (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1611007#msg1611007).  You had no observations.
Your source (which is peer-reviewed) claims it was "well-cemented sedimentary rock" but you claim otherwise.

I will thus tend to side with your source over you, unless you can get published in a peer-reviewed journal a good argument about why not. Burden of proof is still on you, bud.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/02/2020 02:36 pm
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.
...

You just attempted to shift the burden of proof. No. *you* find an example of Mars sandstone being 40% porosity. It doesn't fit with observations.

I showed it four years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859).  You were there (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1611007#msg1611007).  You had no observations.
Your source (which is peer-reviewed) claims it was "well-cemented sedimentary rock" but you claim otherwise.

I will thus tend to side with your source over you, unless you can get published in a peer-reviewed journal a good argument about why not. Burden of proof is still on you, bud.

False and ugly non sequitur.  ::) 

--

Posters might think about trade-offs first in terrestrial terms.  If choosing between, say, caliche trench construction and hilltop construction, in New Mexico, how would you weigh pros and cons?

--

Martian glacier habs (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615) aren't popular here, but there are points in favor.  Recent posts highlight the material contrast.  It's relatively nice, to work with unfractured material that has UCS > 50 MPa, and which vaporizes in excavation, cleanly.

Image:  Haynes 1978, Fig. 4.  Ice UCS vs. temperature.

Mobile, path-tracing DC immersion heater (https://forum.nasaspaceflight.com/index.php?topic=44508.msg1933999#msg1933999) robots could excavate unattended, quickly and indefinitely.  It would be somewhat the inverse of 3D ice hab printing, which seems to interest people more, even though that's harder and space-limited (http://www.marsicehouse.com/). 

Worth a render.

Refs.

Haynes, F.D., 1978. Effect of temperature on the strength of snow-ice (https://apps.dtic.mil/dtic/tr/fulltext/u2/a067583.pdf) (Vol. 78, No. 27). Cold Regions Research and Engineering Laboratory, Corps of Engineers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 09/03/2020 06:54 am
Let me put some things straight. This happens to have been my line of work for several years, so readers can assume I know some basics about rocks.

There is a difference between primary and secondary porosity. Primary porosity is the porosity from when the rock first formed: gaps between the grains, essentially, for sedimentary rock. Secondary porosity is what results from weathering which, in the case of Mars, will include mechanical action from meteorites. I've mentioned this before but I'll bring it up again.

Rock at surface has a higher secondary porosity (due to weathering) than rock underground. This is why we take core samples when we want to dig, and in my line of work, use borehole geophysics.

Mars changes things. The gravity is lower, so a number of things change: rock squeeze is reduced, and pressure relief fracturing due to removal of overburden is going to be different, more gradual. Groundwater is likely extremely saline if it is not frozen. If it is frozen, at like -50C to -80C then it's going to be very different to dry rock that is tested in the lab at 20C. The water content when frozen drastically changes the behaviour of the rock, and not in an intuitive linear way either. What will happen when the water unfreezes in the presence of a warm hab tunnel, or nearby unintended hotspots?

TL;DR: geomechanics is tricky, especially on an alien world. So it makes digging tunnels that much more uncertain.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/03/2020 01:32 pm
There is a difference between primary and secondary porosity. Primary porosity is the porosity from when the rock first formed: gaps between the grains, essentially, for sedimentary rock. Secondary porosity is what results from weathering which, in the case of Mars, will include mechanical action from meteorites. I've mentioned this before but I'll bring it up again.

Rock at surface has a higher secondary porosity (due to weathering) than rock underground.

Do you discount the Meridiani Planum depth/porosity relation (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380)? 

And yes, impact gardening churns the surface, tens to hundreds of meters deep (https://www.sciencedirect.com/science/article/abs/pii/S0019103500965321), depending on surface age.  Hartmann et al. 2001.  But the sampled Gale Crater rocks weren't always on the surface: they were buried km+ deep, then exhumed.  That's why many of the photographed rocks are not disturbed by impact gardening, which doesn't factor into their secondary porosity.  Likewise, their fractures:  e.g., Marimba mudrock (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380), which fractured at creation and during burial, but probably not due to impacts.

So wrt sedimentary rock strength, Gale Crater mudrock is likely near the upper end of the scale.  And even that rock you wouldn't trust for hab tunneling, yes?

Refs.

Hartmann, W.K., Anguita, J., Miguel, A., Berman, D.C. and Ryan, E.V., 2001. Martian cratering 7: The role of impact gardening. (https://www.sciencedirect.com/science/article/abs/pii/S0019103500965321) Icarus, 149(1), pp.37-53.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/03/2020 11:15 pm
If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.

Supporting this claim requires numerical comparison, not just hand-waving.

No, just contrast the difficulty of constructing metal pressurized facilities in a fragile martian excavation, with that of dropping canisters onto the surface.

Your first claim was about the mass of steel involved. To "support" that claim, you're making an entirely new claim about construction difficulty. Neither claim has yet been backed up by anything approaching a quantitative analysis (ie actual numbers).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/03/2020 11:22 pm
Typical martian sandstone has negligible strength (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859), and can't bear load. Likewise most other martian sedimentary stones; unsafe for steep cut-and-cover.

As pointed out by others in that same part of the thread that you link to, 40% porosity is more like foam than rock. Typical porosity of solid sandstone is rarely greater than 20%, even in aquifers, with 8-12% being typical.

No one asked why. 

Mars sandstone is more porous because less compacted.  Hence ~ 40% porosity, matching the weakest sandstone on Earth [Coneybeare 1967].  Steep cut-and-cover would be foolish in such a fragile mess. 

Disagree?  Find an example.
...

You just attempted to shift the burden of proof. No. *you* find an example of Mars sandstone being 40% porosity. It doesn't fit with observations.

I showed it four years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1610859#msg1610859).  You were there (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1611007#msg1611007).  You had no observations.
Your source (which is peer-reviewed) claims it was "well-cemented sedimentary rock" but you claim otherwise.

I will thus tend to side with your source over you, unless you can get published in a peer-reviewed journal a good argument about why not. Burden of proof is still on you, bud.

False and ugly non sequitur.  ::) 

Could we get something more than an embellished version of "nuh uh" maybe?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/04/2020 02:35 am
For underground habs, you're going to need to perform a geologic survey to ensure a safe structure, and bury it relatively deep. For very deep structures (>15-30 m, depending on bulk density), the earth pressure is sufficient to completely counteract the internal pressure, so the surrounding material remains entirely in compression not tension. This should improve reliability greatly. allowing construction in less stable geology.

As we've seen above, martian sedimentary rock is a weak mess; typically too weak for tunnels or steep excavations -- even before accounting for Mag 4+ Starship launch quakes. 

So what "deep structure" are you trying to describe, Twark_Main, and how could it improve upon surface habs?  How could it be easier, cleaner, safer, larger, simpler, etc.? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/04/2020 04:23 am
If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.

Supporting this claim requires numerical comparison, not just hand-waving.

No, just contrast the difficulty of constructing metal pressurized facilities in a fragile martian excavation, with that of dropping canisters onto the surface.

Your first claim was about the mass of steel involved. To "support" that claim, you're making an entirely new claim about construction difficulty. Neither claim has yet been backed up by anything approaching a quantitative analysis (ie actual numbers).
One can make perfectly good engineering arguments without providing you with detailed numbers.

I can tell you that concrete or rock are not good in tension.  I can yell you that water freezing in cracks is a problem for brittle materials.  I can tell you that rock with trapped bubbles/voids is a better insulator than solid rocks..  etc.  All qualitative, but all correct.

You should address the specifics of what LMT says, not just demand "numbers" which may be impossible to get for any number of reasons.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 09/04/2020 05:50 am
There is a difference between primary and secondary porosity. Primary porosity is the porosity from when the rock first formed: gaps between the grains, essentially, for sedimentary rock. Secondary porosity is what results from weathering which, in the case of Mars, will include mechanical action from meteorites. I've mentioned this before but I'll bring it up again.

Rock at surface has a higher secondary porosity (due to weathering) than rock underground.

Do you discount the Meridiani Planum depth/porosity relation (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380)? 

And yes, impact gardening churns the surface, tens to hundreds of meters deep (https://www.sciencedirect.com/science/article/abs/pii/S0019103500965321), depending on surface age.  Hartmann et al. 2001.  But the sampled Gale Crater rocks weren't always on the surface: they were buried km+ deep, then exhumed.  That's why many of the photographed rocks are not disturbed by impact gardening, which doesn't factor into their secondary porosity.  Likewise, their fractures:  e.g., Marimba mudrock (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380), which fractured at creation and during burial, but probably not due to impacts.

So wrt sedimentary rock strength, Gale Crater mudrock is likely near the upper end of the scale.  And even that rock you wouldn't trust for hab tunneling, yes?

Refs.

Hartmann, W.K., Anguita, J., Miguel, A., Berman, D.C. and Ryan, E.V., 2001. Martian cratering 7: The role of impact gardening. (https://www.sciencedirect.com/science/article/abs/pii/S0019103500965321) Icarus, 149(1), pp.37-53.

Here's what your source says.

Quote
Stratigraphic units exposed since Noachian times would have experienced tens to hundreds of meters of gardening. Early Amazonian/late Hesperian sites, such as the first three landing sites, experienced cumulative gardening on the order of 3–14 m, a conclusion that may conflict with some landing site interpretations. Martian surfaces with less than a percent or so of lunar mare crater densities have negligible impact gardening because of a probable cutoff of hypervelocity impact cratering below D∼1 m, due to Mars' atmosphere.

My position on tunnelling and underground works hasn't changed. It is time-consuming, resource intensive and prone to setbacks. However, there is no data on fresh, previously undisturbed underground sedimentary rock. We have 3 good ground-level point references, and remote sensing for the rest of the planet.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/04/2020 03:34 pm
ICEHOTEL (https://www.designboom.com/architecture/icehotel-29-sweden-images-12-17-18/)
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/04/2020 07:11 pm
Illustrative achievable melt-out scale, esp. within Phlegra Montes glacier (https://forum.nasaspaceflight.com/index.php?topic=45762.msg1988091#msg1988091), for:

- hab vaults
- spaceport silos (https://forum.nasaspaceflight.com/index.php?topic=45762.msg1989678#msg1989678)
- tankage
- CAES (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2048759#msg2048759), etc.

Martian compression stress on vaults would be only 38% of terrestrial stress, and martian ice UCS would be at least 2x (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127519#msg2127519) that of the photographed terrestrial ice, so vault scale could conceivably exceed the scale of the illustrative photos.

Vault1:  "A towering ice arch offers expedition members the ultimate photo op." Cotton Coulson and Sisse Brimberg.

Vault2:  Antarctic iceberg.  Zegrahm Expeditions.

Vault3:  "Brooks de Wetter-Smith's photograph of an iceberg titled "Ice Tunnel" (Courtesy of Peabody Essex Museum)."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/05/2020 05:22 pm
For underground habs, you're going to need to perform a geologic survey to ensure a safe structure, and bury it relatively deep. For very deep structures (>15-30 m, depending on bulk density), the earth pressure is sufficient to completely counteract the internal pressure, so the surrounding material remains entirely in compression not tension. This should improve reliability greatly. allowing construction in less stable geology.

As we've seen above, martian sedimentary rock is a weak mess; typically too weak for tunnels or steep excavations -- even before accounting for Mag 4+ Starship launch quakes.

At those depths, your structure could be covered in gravel. Again, by "very deep structures" I'm referring to the depths where the surrounding regolith pressure exceeds the internal atmospheric pressure. This allows you to construct a habitat that requires strength only in compression (generally easier for in-situ materials).


So what "deep structure" are you trying to describe, Twark_Main, and how could it improve upon surface habs?  How could it be easier, cleaner, safer, larger, simpler, etc.?

Answered above.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/05/2020 05:28 pm
If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.

Supporting this claim requires numerical comparison, not just hand-waving.

No, just contrast the difficulty of constructing metal pressurized facilities in a fragile martian excavation, with that of dropping canisters onto the surface.

Your first claim was about the mass of steel involved. To "support" that claim, you're making an entirely new claim about construction difficulty. Neither claim has yet been backed up by anything approaching a quantitative analysis (ie actual numbers).
One can make perfectly good engineering arguments without providing you with detailed numbers.

I can tell you that concrete or rock are not good in tension.  I can yell you that water freezing in cracks is a problem for brittle materials.  I can tell you that rock with trapped bubbles/voids is a better insulator than solid rocks..  etc.  All qualitative, but all correct.

Except you could back all of them up with quantitative analysis. Concrete has a low tensile strength. Rock with bubbles in it has a higher R-value. Water freezing creates large internal pressure.

You should address the specifics of what LMT says, not just demand "numbers" which may be impossible to get for any number of reasons.

When LMT makes a claim that needs addressing, I'll let you know. So far all I've seen is evidence-free hand-waving, which can be dismissed just as easily as it was asserted.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/05/2020 08:52 pm

You should address the specifics of what LMT says, not just demand "numbers" which may be impossible to get for any number of reasons.

When LMT makes a claim that needs addressing, I'll let you know. So far all I've seen is evidence-free hand-waving, which can be dismissed just as easily as it was asserted.

Yeah, no.   I went back and read the OP.  It's a perfectly reasoned argument, not hand-waving.

Your insistence on "numbers" is inappropriate to the conversation, since it requires a level of detailing that you can't achieve either.

You then proceed to focus on this lack of numbers, but you don't provide any of your own.

Without necessarily agreeing with LMT on the topic, I think you're the one that's out of line, and this latest bit of "When LMT makes a claim that needs addressing, I'll let you know." - thanks, but no thanks.  Be excellent etc.  Play the ball not the person. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/05/2020 11:50 pm

You should address the specifics of what LMT says, not just demand "numbers" which may be impossible to get for any number of reasons.

When LMT makes a claim that needs addressing, I'll let you know. So far all I've seen is evidence-free hand-waving, which can be dismissed just as easily as it was asserted.

Yeah, no.   I went back and read the OP.  It's a perfectly reasoned argument, not hand-waving.

Your insistence on "numbers" is inappropriate to the conversation, since it requires a level of detailing that you can't achieve either.

You then proceed to focus on this lack of numbers, but you don't provide any of your own.

Without necessarily agreeing with LMT on the topic, I think you're the one that's out of line, and this latest bit of "When LMT makes a claim that needs addressing, I'll let you know." - thanks, but no thanks.  Be excellent etc.  Play the ball not the person.

Again, when there's a ball to play, I'll play ball. No offense to LMT, he just needs to give me something to work with, but he's presented literally nothing. I'm not asking for a comprehensive engineering breakdown with everything calculated to the smallest detail, just something (anything!) quantitative. I don't think that's too much to ask for.

Let's remember, LMT said:

If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.

I see no "perfectly reasoned argument" anywhere here. It's just a naked assertion.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/05/2020 11:59 pm

You should address the specifics of what LMT says, not just demand "numbers" which may be impossible to get for any number of reasons.

When LMT makes a claim that needs addressing, I'll let you know. So far all I've seen is evidence-free hand-waving, which can be dismissed just as easily as it was asserted.

Yeah, no.   I went back and read the OP.  It's a perfectly reasoned argument, not hand-waving.

Your insistence on "numbers" is inappropriate to the conversation, since it requires a level of detailing that you can't achieve either.

You then proceed to focus on this lack of numbers, but you don't provide any of your own.

Without necessarily agreeing with LMT on the topic, I think you're the one that's out of line, and this latest bit of "When LMT makes a claim that needs addressing, I'll let you know." - thanks, but no thanks.  Be excellent etc.  Play the ball not the person.

Again, when there's a ball to play, I'll play ball. No offense to LMT, he just needs to give me something to work with, but he's presented literally nothing. I'm not asking for a comprehensive engineering breakdown with everything calculated to the smallest detail, just something (anything!) quantitative. I don't think that's too much to ask for.

Let's remember, LMT said:

If you're shoring up fragile rock with, say, linings of steel pipe, you could have used the same steel more efficiently in surface habs.

I see no "perfectly reasoned argument" anywhere here. It's just a naked assertion.
And..  do you have a counter argument for why shoring up rock is more efficient?

There plenty arguments to go both ways, but pre-made steel canisters (a la starship) are optimized and super mass efficient, whereas supporting a rock formation has to take into account the various unknowns about the rock, plus transmit loads from one type of structure (rock, mostly compressive) to another (Steel girders of some sort), which is always a pain and inefficient.

Whether this is arm waving or common engineering sense - at least try to show why a structure made from local rock and steel reinforcements will use less steel..

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/06/2020 12:03 am
And..  do you have a counter argument for why shoring up rock is more efficient?

I'm not the one making a positive claim that one is more mass-efficient than the other. You're confusing me with LMT.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RotoSequence on 09/06/2020 12:07 am
To briefly derail the topic again, I'm not the only one who thinks a tensile load bearing structure is a bad idea, am I? If the hab loses atmospheric containment, any leak is going to be amplified by any pressure from the covering serving as your radiation shield, and in a worst case scenario, could collapse the habitat entirely. IMO it would be dangerously irresponsible to build anything but a structure that could bear the weight of whatever you put on top of it wholly in compression.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 02:09 am
To briefly derail the topic again, I'm not the only one who thinks a tensile load bearing structure is a bad idea, am I? If the hab loses atmospheric containment, any leak is going to be amplified by any pressure from the covering serving as your radiation shield, and in a worst case scenario, could collapse the habitat entirely. IMO it would be dangerously irresponsible to build anything but a structure that could bear the weight of whatever you put on top of it wholly in compression.
IMO they'll tunnel deep enough to achieve pretty much that.  The ground above won't care one bit if the enclosed volume is pressurized or not.

Until then, they'll live in Starships or prefab containers that can be transported by them.

Surface structures will continue to exist (maybe for agriculture) but I think they'll remain prefabbed, even if from local materials.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/06/2020 03:58 am
To briefly derail the topic again, I'm not the only one who thinks a tensile load bearing structure is a bad idea, am I? If the hab loses atmospheric containment, any leak is going to be amplified by any pressure from the covering serving as your radiation shield, and in a worst case scenario, could collapse the habitat entirely. IMO it would be dangerously irresponsible to build anything but a structure that could bear the weight of whatever you put on top of it wholly in compression.
IMO they'll tunnel deep enough to achieve pretty much that.  The ground above won't care one bit if the enclosed volume is pressurized or not.

Until then, they'll live in Starships or prefab containers that can be transported by them.

Surface structures will continue to exist (maybe for agriculture) but I think they'll remain prefabbed, even if from local materials.

Translucent bags, e.g. ETFE (https://omnexus.specialchem.com/selection-guide/ethylene-tetrafluoroethylene-etfe-plastic), could store water ice overhead.  This transmits sunlight into ceiling glass, while protecting against cosmic rays.

How would roof dirt improve on that?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 09/06/2020 05:53 am
To briefly derail the topic again, I'm not the only one who thinks a tensile load bearing structure is a bad idea, am I? If the hab loses atmospheric containment, any leak is going to be amplified by any pressure from the covering serving as your radiation shield, and in a worst case scenario, could collapse the habitat entirely. IMO it would be dangerously irresponsible to build anything but a structure that could bear the weight of whatever you put on top of it wholly in compression.
IMO they'll tunnel deep enough to achieve pretty much that.  The ground above won't care one bit if the enclosed volume is pressurized or not.

Until then, they'll live in Starships or prefab containers that can be transported by them.

Surface structures will continue to exist (maybe for agriculture) but I think they'll remain prefabbed, even if from local materials.

Translucent bags, e.g. ETFE (https://omnexus.specialchem.com/selection-guide/ethylene-tetrafluoroethylene-etfe-plastic), could store water ice overhead.  This transmits sunlight into ceiling glass, while protecting against cosmic rays.

How would roof dirt improve on that?
I think one of the problems is pressure. If you're going to dig underground anyway for radiation protection then it pays to dig a bit deeper and pressure containment is relatively easy. But on the surface with water ice as a radiation shield you will still have the pressure issue unless you make the ice shield hugely thick.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 09/06/2020 01:23 pm
Ice construction may be Ok in mid latitudes, but is it still doable near the equator, where summer day temperatures are above freezing?  You won't be building an ice palace in Dubai :-)
Although I wouldn't put it past them... but as a stunt rather than a practical construction.

I don't see these discussions as cases of absolute decisions one way or another.  On Earth we still have both steel and concrete buildings, or even wooden ones.  Very site dependent, and I expect there will also be site dependency on Mars.  There will be tunnels in sandstone if there are places where the sandstone is sufficiently strong, or filled with ice as an adequate binder.  There may be spots where it's really easy to move regolith around and bury, or half bury, surface habitats.  there may be other places where ice bags or pure ice structures make sense.  I think lava tubes are still a possibility, where these are available.

The question of tension vs compression should really be discussed as a safety issue: How probable is a pressure failure in a pressurized enveloppe, what is the likelihood of an accident and what are the consequences?  Can we treat this the way building codes treat earthquakes as limit state design, or fires as a time of escape design?  Is it sufficient to ensure than anyone living in a collapsible building has time to get out before it gets too dangerous?  Can we define categories of buildings, ones that can collapse (offices?) and others than can't (hospitals, places where people sleep?)

There won't be a one size fits all design, and the design requirements will also change with time.  A few Starship hulls may be ok at first, but if the settlement grows they will definitely need more than that!

In Situ resources will be required eventually, and that can be analysed using considerations such as ease of construction and embodied energy.  http://marspedia.org/Embodied_energy. 

Aggregate is a lot cheaper than anything else, even cheaper than water by a factor of 5 or so. But if you need tensile structures whatever the nature of the construction (even in basaltic rock tunnels)  then that will be the governing material.
And the other question is leaks:  If we need to prevent leakage to avoid continuously producing large amounts of breathable atmosphere, what is the final difference between the leak proofing and a strong tensile envelope?



Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 01:30 pm
The thing about tunneling is it is scalable.

Musk doesn't want to build a habitat or a station. He wants a city.  A tunneling machine just goes on forever..  literally for miles... And once underground, all the construction is pressurized..  I just don't see how you can beat that.
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 09/06/2020 01:35 pm
As a somewhat off topic question related to 2 posts up. If the air evacuates can a human survive with a helmet/ face mask of oxygen at 4 psi survive? I selected 4 psi because I remember from scuba diving that 4 feet is enough to explode a lung if you take a deep breath and go up 4 feet. Of course 4 feet is 4/33*15psi = 2psi so there is that.

EDIT:
Looking for the fastest don-able gear to survive.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 09/06/2020 01:44 pm
Ice construction may be Ok in mid latitudes, but is it still doable near the equator, where summer day temperatures are above freezing?  You won't be building an ice palace in Dubai :-)
Although I wouldn't put it past them... but as a stunt rather than a practical construction.

I don't see these discussions as cases of absolute decisions one way or another.  On Earth we still have both steel and concrete buildings, or even wooden ones.  Very site dependent, and I expect there will also be site dependency on Mars.  There will be tunnels in sandstone if there are places where the sandstone is sufficiently strong, or filled with ice as an adequate binder.  There may be spots where it's really easy to move regolith around and bury, or half bury, surface habitats.  there may be other places where ice bags or pure ice structures make sense.  I think lava tubes are still a possibility, where these are available.

The question of tension vs compression should really be discussed as a safety issue: How probable is a pressure failure in a pressurized enveloppe, what is the likelihood of an accident and what are the consequences?  Can we treat this the way building codes treat earthquakes as limit state design, or fires as a time of escape design?  Is it sufficient to ensure than anyone living in a collapsible building has time to get out before it gets too dangerous?  Can we define categories of buildings, ones that can collapse (offices?) and others than can't (hospitals, places where people sleep?)

There won't be a one size fits all design, and the design requirements will also change with time.  A few Starship hulls may be ok at first, but if the settlement grows they will definitely need more than that!

In Situ resources will be required eventually, and that can be analysed using considerations such as ease of construction and embodied energy.  http://marspedia.org/Embodied_energy. 

Aggregate is a lot cheaper than anything else, even cheaper than water by a factor of 5 or so. But if you need tensile structures whatever the nature of the construction (even in basaltic rock tunnels)  then that will be the governing material.
And the other question is leaks:  If we need to prevent leakage to avoid continuously producing large amounts of breathable atmosphere, what is the final difference between the leak proofing and a strong tensile envelope?
One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 01:48 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 09/06/2020 01:59 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
Possibly, but what would happen if there was a large area of ice above the tunnel but below the surface? Any escaping heat from the tunnel might destabilise that ice. Perhaps they might just drill a lot of test holes above and round the tunnel or scan it somehow?
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 02:09 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
Possibly, but what would happen if there was a large area of ice above the tunnel but below the surface? Any escaping heat from the tunnel might destabilise that ice. Perhaps they might just drill a lot of test holes above and round the tunnel or scan it somehow?
I don't think you ever drill blind...  In order for ice to be a problem it has to either reach the actual tunnel (and so be detectable on the inner wall) or be a very large deposit (mass wise) from the surface and almost to the tunnel, so I think it can be surveyed..

Probably also possible to detect temperature signature on the inner tunnel walls..  Too cold means there's high conductivity to the surface, too hot means there's a void..

I'm sure there are acoustical methods to measure this too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 09/06/2020 02:13 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
What is the difference between a non structural liner and a structural liner?  Besides the obvious structural issue :-)
When does a mm of some kind of flexible wear proof material become equivalent to a few mm of steel?  In particular when it is produced in-situ?  Steel is cheaper than all types of plastic by a long shot.  And what are the failure modes of the liner, including decay over time (that means rust for steel as well).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 09/06/2020 02:19 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
Possibly, but what would happen if there was a large area of ice above the tunnel but below the surface? Any escaping heat from the tunnel might destabilise that ice. Perhaps they might just drill a lot of test holes above and round the tunnel or scan it somehow?
Nothing happens to the ice.
In order to be livable the tunnel requires certain interior atmosphere characteristics.  One of these is relative humidity.  The other is temperature gradients.  In order to avoid untenable amounts of condensation and very uncomfortable gradients neat the tunnel walls, these will need to be insulated.  After all martian soil is on average at -68C.
It is a fairly trivial addition, as well as being economically sound, to install insulation that reduces the heat loss a point where the external ice will never melt.
It's inherent in the tunnel design, imho.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 02:20 pm
What is the difference between a non structural liner and a structural liner?  Besides the obvious structural issue :-)
When does a mm of some kind of flexible wear proof material become equivalent to a few mm of steel?  In particular when it is produced in-situ?  Steel is cheaper than all types of plastic by a long shot.  And what are the failure modes of the liner, including decay over time (that means rust for steel as well).
Material cost has nothing to do with it (since we're on Mars), and besides, you're quoting per pound, right?  Steel is very dense compared to a plastic sealer.

Steel has minimum gauge and rigidity (you can't apply a steel foil to a jugged wall)..  A sealant can be applied selectively, non uniformly, and is conformal..

--

The inner tube in a tubed tire is non structural. It can resist pressure only with the support of the tire, which itself can be non sealing.  The inner tube will conform to the shape dictated by the tire and the wheel, which are structural.

Then  you can add a totally liquid gel in there which actually flows out of small pressure punctures and seals them..

(Those are examples to your question, not a 1:1 mars tunnel architecture)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 09/06/2020 02:39 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
What is the difference between a non structural liner and a structural liner?  Besides the obvious structural issue :-)
When does a mm of some kind of flexible wear proof material become equivalent to a few mm of steel?  In particular when it is produced in-situ?  Steel is cheaper than all types of plastic by a long shot.  And what are the failure modes of the liner, including decay over time (that means rust for steel as well).
Material cost has nothing to do with it (since we're on Mars), and besides, you're quoting per pound, right?

Steel has minimum gauge and rigidity..  a sealant can be applied selectively and is conformal..

--

The inner tube in a tubed tire is non structural. It can resist pressure only with the support of the tire, which itself can be non sealing.  The inner tube will conform to the shape dictated by the tire and the wheel, which are structural.

Then  you can add a totally liquid gel in there which actually flows out of small pressure punctures and seals them..

(Those are examples to your question, not a 1:1 mars tunnel architecture)
Material costs on Mars will be as important as on Earth.  First adequacy, then cost.  Steel is very dense and that certainly reduces the interest in that material.  Plastics are not dense, but very expensive to produce in-situ.  I don't know which is worst, But I think it is not in favor of sealants.  How much of the tunnel surface needs to be sealed anyway?  Isn't it 100% in the case of xx% porous rock?  I guess tunnels made in basalt might be better, but even then all rocks have cracks and leaks. 
One of the interests of the canadian shield is that it is quite leakproof, and therefore supports a large amounts of lakes, than can then be used as reservoirs for dams.  The dams themselves are made of clay, mostly.. 
This does raise the opportunity of using clays rather than plastics for sealant though.  A few inches of competent clay with a thin layer of something on top?

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 02:42 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
What is the difference between a non structural liner and a structural liner?  Besides the obvious structural issue :-)
When does a mm of some kind of flexible wear proof material become equivalent to a few mm of steel?  In particular when it is produced in-situ?  Steel is cheaper than all types of plastic by a long shot.  And what are the failure modes of the liner, including decay over time (that means rust for steel as well).
Material cost has nothing to do with it (since we're on Mars), and besides, you're quoting per pound, right?

Steel has minimum gauge and rigidity..  a sealant can be applied selectively and is conformal..

--

The inner tube in a tubed tire is non structural. It can resist pressure only with the support of the tire, which itself can be non sealing.  The inner tube will conform to the shape dictated by the tire and the wheel, which are structural.

Then  you can add a totally liquid gel in there which actually flows out of small pressure punctures and seals them..

(Those are examples to your question, not a 1:1 mars tunnel architecture)
Material costs on Mars will be as important as on Earth.  First adequacy, then cost.  Steel is very dense and that certainly reduces the interest.  Plastics are not dense, but very expensive to produce in-situ.  I don't know which is worst, But I think it is not in favor of sealants.  How much of the tunnel surface needs to be sealed anyway?  Isn't it 100% in the case of xx% porous rock?  I guess tunnels made in basalt might be better, but even then all rocks have cracks and leaks. 
One of the interests of the canadian shield is that it is quite leakproof, and therefore supports a large amounts of lakes, than can then be used as reservoirs for dams.  The dams themselves are made of clay. 
This does raise the opportunity of using clays rather than plastics for sealant though.  A few inches of competent clay with a thin layer of something on top?
Unless you have a way to line up irregular tunnel walls with thin steel, you'll end up with a lot more steel than sealant.  Even on earth this is not something that's done.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 09/06/2020 03:46 pm


One problem underground might be it's unpredictable nature with faults, multiple fractures and pockets of ice, boulders or sand/dust.
Once you're deep enough that the tunnel is structurally sound, I think this is handled by a non structural liner//sealer where necessary.
What is the difference between a non structural liner and a structural liner?  Besides the obvious structural issue :-)
When does a mm of some kind of flexible wear proof material become equivalent to a few mm of steel?  In particular when it is produced in-situ?  Steel is cheaper than all types of plastic by a long shot.  And what are the failure modes of the liner, including decay over time (that means rust for steel as well).
Material cost has nothing to do with it (since we're on Mars), and besides, you're quoting per pound, right?

Steel has minimum gauge and rigidity..  a sealant can be applied selectively and is conformal..

--

The inner tube in a tubed tire is non structural. It can resist pressure only with the support of the tire, which itself can be non sealing.  The inner tube will conform to the shape dictated by the tire and the wheel, which are structural.

Then  you can add a totally liquid gel in there which actually flows out of small pressure punctures and seals them..

(Those are examples to your question, not a 1:1 mars tunnel architecture)
Material costs on Mars will be as important as on Earth.  First adequacy, then cost.  Steel is very dense and that certainly reduces the interest.  Plastics are not dense, but very expensive to produce in-situ.  I don't know which is worst, But I think it is not in favor of sealants.  How much of the tunnel surface needs to be sealed anyway?  Isn't it 100% in the case of xx% porous rock?  I guess tunnels made in basalt might be better, but even then all rocks have cracks and leaks. 
One of the interests of the canadian shield is that it is quite leakproof, and therefore supports a large amounts of lakes, than can then be used as reservoirs for dams.  The dams themselves are made of clay. 
This does raise the opportunity of using clays rather than plastics for sealant though.  A few inches of competent clay with a thin layer of something on top?
Unless you have a way to line up irregular tunnel walls with thin steel, you'll end up with a lot more steel than sealant.  Even on earth this is not something that's done.
Well you don't seal mining shafts, but you do line most tunnels, no?  As far as I know tunnels are bored larger than the final size, then lined with pre-cast steel reinforced concrete?  There are rocks where this is not required though.  But are they common or fairly rare?
Perhaps we need to establish exactly what we are talking about to avoid talking past one another.
Here joined is the British tunnel lining design guide.  As it wisely suggest we need to first establish the tunnel lining requirements, characterise the rock and identify the loads.

-There is at least one fairly unique Martian characteristic, with the soil/rock at an average temperature of -68C.
-The tunnel is pressurized to about 1 atmosphere above ambient pressure.
-The main purpose is habitation, but it also has any number of secondary purposes.
-Loss of pressure may lead to loss of life.
-Interior temperature at 2 to 26C, relative humidity 20-50%.  Comfort zone.

Perhaps the fist question would be must the tunnel be insulated, and what are the impacts of this on the tunnel design?




Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/06/2020 05:11 pm
[snip]

Material costs on Mars will be as important as on Earth.  First adequacy, then cost.  Steel is very dense and that certainly reduces the interest in that material.  Plastics are not dense, but very expensive to produce in-situ.  I don't know which is worst, But I think it is not in favor of sealants.  How much of the tunnel surface needs to be sealed anyway?  Isn't it 100% in the case of xx% porous rock?  I guess tunnels made in basalt might be better, but even then all rocks have cracks and leaks.

The great thing about liners vs. pressure vessels is that your liner cost scales with surface area, not with volume. If you make your pressure vessel twice the diameter (4x the volume), the pressure vessel needs to be 4x as massive. If you make your tunnel twice the diameter, the liner only needs to be 2x as massive.

The mass we're talking about is rather small. Transhab used three layers of Combitherm (a plastic film used for vacuum sealed food packaging) with a thickness of 140 micrometers each. That's equivalent in mass to a steel liner only 0.06 mm thick. So as long as your tunnel is larger than 0.26 m in diameter, the liner will be less massive. If steel is (say) 10x cheaper than plastic per kg, that means that a tunnel larger than 2.6 m in diameter is cheaper, at least for the liner vs. pressure vessel cost.

There are new lightweight films (eg using AlO barriers instead of EVOH) which achieve even lower gas permeability (https://www.nasa.gov/centers/johnson/pdf/486065main_HRP-AFT-Packaging-Poster(Feb2008).pdf). IIRC the new films can also be made thinner/lighter than Combitherm, but I can't seem to find those data at the moment.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 09/06/2020 05:38 pm
The thing about tunneling is it is scalable.

Musk doesn't want to build a habitat or a station. He wants a city.  A tunneling machine just goes on forever..  literally for miles... And once underground, all the construction is pressurized..  I just don't see how you can beat that.

A bulldozer on the surface also just goes on forever.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 05:42 pm
The thing about tunneling is it is scalable.

Musk doesn't want to build a habitat or a station. He wants a city.  A tunneling machine just goes on forever..  literally for miles... And once underground, all the construction is pressurized..  I just don't see how you can beat that.

A bulldozer on the surface also just goes on forever.
But that only gets you a trench.  Now you have to cover with something that holds pressure.

A tunnel, once you're in, you're done.
Bore into a hillside, and you're even getting more cover as you go further in.

If there's any seepage into the rock, apply sealant.

A hillside will quickly get you to where you're hundreds of feet under the surface..  now you can go multilevel, and again, no other structure is necessary.

Hence "scalable".  Per volume, it gets easier the larger you go.  Other structures, if you want 50x the liveable volume, you need to build 50x the structure..
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/06/2020 06:01 pm
The thing about tunneling is it is scalable.

Musk doesn't want to build a habitat or a station. He wants a city.  A tunneling machine just goes on forever..  literally for miles... And once underground, all the construction is pressurized..  I just don't see how you can beat that.

Your TBM would approximate Bertha's (https://newatlas.com/bertha-boring-machine-seattle/48862/) 17.4 m structure, delivered by 2nd-gen 18-m Starships.

Altogether ~ 10,000 tons delivered before first scoop.  No better way to use that mass?
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 06:04 pm
The thing about tunneling is it is scalable.

Musk doesn't want to build a habitat or a station. He wants a city.  A tunneling machine just goes on forever..  literally for miles... And once underground, all the construction is pressurized..  I just don't see how you can beat that.

Your TBM would approximate Bertha's (https://newatlas.com/bertha-boring-machine-seattle/48862/) 17.4 m structure, delivered by 2nd-gen 18-m Starships.

Altogether ~ 10,000 tons delivered before first scoop.  No better way to use that mass?
Why so large?

Parallel 3.7 bores is plenty fine...  one for conveyance, the rest for habitation...

Per mile excavated / volume created, the weight of the machine is a lot less then that of habitats..

You're not paying attention to TBC..  They have a self-starting 3.7 m machine...  Musk is not thinking about Berthas..  That's old-tunnel-industry...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 09/06/2020 06:54 pm
[snip]

Material costs on Mars will be as important as on Earth.  First adequacy, then cost.  Steel is very dense and that certainly reduces the interest in that material.  Plastics are not dense, but very expensive to produce in-situ.  I don't know which is worst, But I think it is not in favor of sealants.  How much of the tunnel surface needs to be sealed anyway?  Isn't it 100% in the case of xx% porous rock?  I guess tunnels made in basalt might be better, but even then all rocks have cracks and leaks.

The great thing about liners vs. pressure vessels is that your liner cost scales with surface area, not with volume. If you make your pressure vessel twice the diameter (4x the volume), the pressure vessel needs to be 4x as massive. If you make your tunnel twice the diameter, the liner only needs to be 2x as massive.

The mass we're talking about is rather small. Transhab used three layers of Combitherm (a plastic film used for vacuum sealed food packaging) with a thickness of 140 micrometers each. That's equivalent in mass to a steel liner only 0.06 mm thick. So as long as your tunnel is larger than 0.26 m in diameter, the liner will be less massive. If steel is (say) 10x cheaper than plastic per kg, that means that a tunnel larger than 2.6 m in diameter is cheaper, at least for the liner vs. pressure vessel cost.

There are new lightweight films (eg using AlO barriers instead of EVOH) which achieve even lower gas permeability (https://www.nasa.gov/centers/johnson/pdf/486065main_HRP-AFT-Packaging-Poster(Feb2008).pdf). IIRC the new films can also be made thinner/lighter than Combitherm, but I can't seem to find those data at the moment.
Interesting, I thought it was much thicker.  Would it require some form of backing or surface preparation?  I imagine it couldn't bridge significant gaps, so there would need to be surface preparation to create a fairly smooth surface?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/06/2020 06:55 pm
[snip]

Material costs on Mars will be as important as on Earth.  First adequacy, then cost.  Steel is very dense and that certainly reduces the interest in that material.  Plastics are not dense, but very expensive to produce in-situ.  I don't know which is worst, But I think it is not in favor of sealants.  How much of the tunnel surface needs to be sealed anyway?  Isn't it 100% in the case of xx% porous rock?  I guess tunnels made in basalt might be better, but even then all rocks have cracks and leaks.

The great thing about liners vs. pressure vessels is that your liner cost scales with surface area, not with volume. If you make your pressure vessel twice the diameter (4x the volume), the pressure vessel needs to be 4x as massive. If you make your tunnel twice the diameter, the liner only needs to be 2x as massive.

The mass we're talking about is rather small. Transhab used three layers of Combitherm (a plastic film used for vacuum sealed food packaging) with a thickness of 140 micrometers each. That's equivalent in mass to a steel liner only 0.06 mm thick. So as long as your tunnel is larger than 0.26 m in diameter, the liner will be less massive. If steel is (say) 10x cheaper than plastic per kg, that means that a tunnel larger than 2.6 m in diameter is cheaper, at least for the liner vs. pressure vessel cost.

There are new lightweight films (eg using AlO barriers instead of EVOH) which achieve even lower gas permeability (https://www.nasa.gov/centers/johnson/pdf/486065main_HRP-AFT-Packaging-Poster(Feb2008).pdf). IIRC the new films can also be made thinner/lighter than Combitherm, but I can't seem to find those data at the moment.
Interesting, I thought it was much thicker.  Would it require some form of backing or surface preparation?  I imagine it couldn't bridge significant gaps, so there would need to be surface preparation to create a fairly smooth surface?

Yep. I think your suggestion of clay or grout would work for surface prep.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/06/2020 06:58 pm
[snip]

Material costs on Mars will be as important as on Earth.  First adequacy, then cost.  Steel is very dense and that certainly reduces the interest in that material.  Plastics are not dense, but very expensive to produce in-situ.  I don't know which is worst, But I think it is not in favor of sealants.  How much of the tunnel surface needs to be sealed anyway?  Isn't it 100% in the case of xx% porous rock?  I guess tunnels made in basalt might be better, but even then all rocks have cracks and leaks.

The great thing about liners vs. pressure vessels is that your liner cost scales with surface area, not with volume. If you make your pressure vessel twice the diameter (4x the volume), the pressure vessel needs to be 4x as massive. If you make your tunnel twice the diameter, the liner only needs to be 2x as massive.

The mass we're talking about is rather small. Transhab used three layers of Combitherm (a plastic film used for vacuum sealed food packaging) with a thickness of 140 micrometers each. That's equivalent in mass to a steel liner only 0.06 mm thick. So as long as your tunnel is larger than 0.26 m in diameter, the liner will be less massive. If steel is (say) 10x cheaper than plastic per kg, that means that a tunnel larger than 2.6 m in diameter is cheaper, at least for the liner vs. pressure vessel cost.

There are new lightweight films (eg using AlO barriers instead of EVOH) which achieve even lower gas permeability (https://www.nasa.gov/centers/johnson/pdf/486065main_HRP-AFT-Packaging-Poster(Feb2008).pdf). IIRC the new films can also be made thinner/lighter than Combitherm, but I can't seem to find those data at the moment.
Interesting, I thought it was much thicker.  Would it require some form of backing or surface preparation?  I imagine it couldn't bridge significant gaps, so there would need to be surface preparation to create a fairly smooth surface?
For large fissures/crevices you'll first fill them with foam. But that's applied as-needed, not uniformly over the entire surface.

And again, we're not a few feet under the surface where a crack can result in the pressure lifting the roof off.  We're tens, hundreds of feet from the surface.  The foam only needs to seal, not hold anything structural.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/06/2020 07:20 pm
The thing about tunneling is it is scalable.

Musk doesn't want to build a habitat or a station. He wants a city.  A tunneling machine just goes on forever..  literally for miles... And once underground, all the construction is pressurized..  I just don't see how you can beat that.

A bulldozer on the surface also just goes on forever.
But that only gets you a trench.  Now you have to cover with something that holds pressure.

A tunnel, once you're in, you're done.
Bore into a hillside, and you're even getting more cover as you go further in.

If there's any seepage into the rock, apply sealant.

A hillside will quickly get you to where you're hundreds of feet under the surface..  now you can go multilevel, and again, no other structure is necessary.

Hence "scalable".  Per volume, it gets easier the larger you go.  Other structures, if you want 50x the liveable volume, you need to build 50x the structure..


Exactly.

I started saying that probably a hundred pages back in this thread, which just goes to show that good ideas won't die. :-)

We should bring building equipment to Mars, not building materials.

(Or, anyway, just the minimum amount of building materials,, such as liners and sealing components).

An electric TBM and an electric roadheader with lots of spare parts should get us started on producing lots of underground internal volume. Just like on Earth the first dwellings for people on Mars will be underground. At a later stage it will be possible to move into those fancy topside houses.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 09/06/2020 07:33 pm
Seems to me that underground habs will not happen quickly. The ground needs to be properly surveyed and they need to get a good grip on in situ resource utilisation of building materials as opposed to ISRU for propellants. This will take a lot of in situ technical experimentation and refinement to get right.

If they want an efficient process for materials they will take a combined approach to the regolith processing to meet many needs. Crushing, magnetic separation, calcining, water treatment and precipitation, centrifugal separation and pressure swing adsorption to separate range of feed stock materials. Gases such as oxygen, water vapour, nitrogen and sulphur oxides as well as a range of solids such as iron, aluminium, titanium and silicon oxides and many more.

These could then be further processed into a wide range of materials of a reliable quality for construction such as iron, cements, bricks and blocks among many others. An expansion from the ISRU propellant production processes will be able to generate ethylene and from there a range of plastics and organic adhesives, sealants and similar.

This will all require a lot of energy and a lot of development work so it won’t happen quickly, but when it does I imagine they will be ready to start an underground hab city.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Frogstar_Robot on 09/06/2020 09:24 pm
The ground needs to be properly surveyed

Does it though? What's the worst that can happen on Mars if you just started boring a tunnel and lining it? If a tunnel hits a hitch, you could just start a new one, if you just want living space, rather than specifically connecting point A to point B.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Nevyn72 on 09/06/2020 10:15 pm
I would imagine you need to minimise the amount of material used to line underground structure that is imported from Earth as much as possible. However the bulk lining requirements are likely to be significant in terms of quantity.....

Why not do the bulk of your lining with a Martian regolith derived form of 'shotcrete' to produce a largely uniform and smooth surface. You could even potentially bind it with water.

This provides most of the structural form and is then lined with a smaller amount of insulated product, ideally with an air-gap.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/07/2020 02:06 am
What's the worst that can happen on Mars if you just started boring a tunnel and lining it?

You might compile an NSF list, for reference.

1. bearing failure

https://www.youtube.com/watch?v=egUCzfhWFgY
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/07/2020 03:53 am
What's the worst that can happen on Mars if you just started boring a tunnel and lining it?

You might compile an NSF list, for reference.

1. bearing failure

https://www.youtube.com/watch?v=egUCzfhWFgY

You keep bringing up the world's largest TBM (at least according to youTube)...

TBC's boring machines are much smaller and are already self-starting from the surface so do not need a starting pit.

A mars machine may be even smaller.  The failure modes (and their consequences) don't translate. With multiple machines, if one dies irrevocably, it's not the end of the world.

TBMs will remove material efficiently, and give the colonists access to an infinite pressurized volume.

Once at depth, the amount of consumables (sealant) will decrease even further, and I honestly don't see any other construction method coming close in terms of scalability.

Again, this is not about how to build a small number of habitats on the surface.  For that, go on and debate canisters vs. trench and cover vs. all sorts of tricks.   But to deal with a growing colony, a tunneling system is the easiest way to use Mars material for structure, pressure containment, and radiation shielding.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 09/08/2020 03:17 am
The ground needs to be properly surveyed
Does it though? What's the worst that can happen on Mars if you just started boring a tunnel and lining it? If a tunnel hits a hitch, you could just start a new one, if you just want living space, rather than specifically connecting point A to point B.

However, a TBM-type tunnelling machine (a la The Boring Company, which is what meekGee is referencing) can't be removed from a tunnel that's being occupied behind it, nor can it back up to veer off at sharp angles to make a new tunnel. (A road-header is more flexible and might be a better option.)

MG seems to be picturing two TBMs in two parallel tunnels, one housing the habitat, one for the spoil-line + utilities + crew/parts-access, both somehow pressurised (**), with cross-links dug between them to allow the excavated spoil out of both tunnels to be shipped through one. In that case, if the cutting face hits unworkable material, then at least one of your TBMs is trapped by the habitat and can't be removed without complete disassembly. The other would require removal of the whole supporting infrastructure behind it before it would be backed out and moved to a new site. A slow and labour-intensive process.

Note, that's your "best case". Ie, you detect the problem before it causes actual damage.

"What's the worst that can happen" is if the tunnel collapses and destroys the TBMs, plus breaches the pressurised tunnels and kills your workers. (I assume the habitat is independently pressurised, but that has been glossed over.)


** (How do you remove spoil from a pressurised (sealed) tunnel? You'd need an airlock. The volume of material removed (by definition) equals at least the volume of the excavation. In practice it's much more, since loose material has a lower density than solid. Gravel is usually double rock. So twice the volume of spoil as tunnel volume, and since one tunnel is entirely for servicing the cutting faces, at least four times the habitable volume.

There seems to be a common image that once you dig a certain way in, you can close the door behind you and continue digging without access to the surface. As if the material dug out simply disappears (or shrinks drastically in volume.) The video-game version of mining.

The exception is if you a digging directly into ice as both your water "mine" and your habitat volume. You still need to pump the water to the industrial sites, but that's easier than transporting fresh cut gravel/dust.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/08/2020 03:44 am
The exception is if you a digging directly into ice as both your water "mine" and your habitat volume.

Hab ice wouldn't be dug; just melted in place, using hw much simpler and lighter than the impractical TBMs, etc.  Note recent posts.  1 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615) 2 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127519#msg2127519) 3 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2128635#msg2128635)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/08/2020 05:04 am
The ground needs to be properly surveyed
Does it though? What's the worst that can happen on Mars if you just started boring a tunnel and lining it? If a tunnel hits a hitch, you could just start a new one, if you just want living space, rather than specifically connecting point A to point B.

However, a TBM-type tunnelling machine (a la The Boring Company, which is what meekGee is referencing) can't be removed from a tunnel that's being occupied behind it, nor can it back up to veer off at sharp angles to make a new tunnel. (A road-header is more flexible and might be a better option.)

MG seems to be picturing two TBMs in two parallel tunnels, one housing the habitat, one for the spoil-line + utilities + crew/parts-access, both somehow pressurised (**), with cross-links dug between them to allow the excavated spoil out of both tunnels to be shipped through one. In that case, if the cutting face hits unworkable material, then at least one of your TBMs is trapped by the habitat and can't be removed without complete disassembly. The other would require removal of the whole supporting infrastructure behind it before it would be backed out and moved to a new site. A slow and labour-intensive process.

Note, that's your "best case". Ie, you detect the problem before it causes actual damage.

"What's the worst that can happen" is if the tunnel collapses and destroys the TBMs, plus breaches the pressurised tunnels and kills your workers. (I assume the habitat is independently pressurised, but that has been glossed over.)


** (How do you remove spoil from a pressurised (sealed) tunnel? You'd need an airlock. The volume of material removed (by definition) equals at least the volume of the excavation. In practice it's much more, since loose material has a lower density than solid. Gravel is usually double rock. So twice the volume of spoil as tunnel volume, and since one tunnel is entirely for servicing the cutting faces, at least four times the habitable volume.

There seems to be a common image that once you dig a certain way in, you can close the door behind you and continue digging without access to the surface. As if the material dug out simply disappears (or shrinks drastically in volume.) The video-game version of mining.

The exception is if you a digging directly into ice as both your water "mine" and your habitat volume. You still need to pump the water to the industrial sites, but that's easier than transporting fresh cut gravel/dust.)
I put a bit more thought into it, but the discussion was about tunneling vs. surface habitats as a long term solution, not about how to tunnel.

Clearly tunneling for space on Mars is different than tunneling for transportation in a city on Earth.

Most everything you mention is solvable when you design the TBM.

--

A removable head is jot impossible to build, but it's also possible to go in a mile or two, curve around, and come back out.

Or, go under a hillside and emerge at the other end.

Or, just like you dug in from the surface, dig out to the surface.

--

You will need an airlock of course amyway, so what's the problem evacuating the tailings?  How fast is the machine moving again?

If you cam evacuate the tailings fast enough, you're in damn good shape.

--

Road headers will be necessary to cross connect parallel bores and do some local enlargements..  but I can't imagine they'll be anywhere near as efficient or fast as a cutting disc.

--

Cutting into a glacier is absolutely an option, if an appropriately thick and stable one is found.  There are ups and downs to it though..  rock is much stronger than ice...  And much more permanent. 

I can see both options used concurrently.

Overall I see building under ice or under rock as relatively similar, when compared to building structures on the surface.

You can add salt deposits as another variant.

--

LMT keeps thinking about Big Bertha, but I expect  TBC's machines to be very different.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 09/08/2020 06:44 am
The ground needs to be properly surveyed
Does it though? What's the worst that can happen on Mars if you just started boring a tunnel and lining it? If a tunnel hits a hitch, you could just start a new one, if you just want living space, rather than specifically connecting point A to point B.

However, a TBM-type tunnelling machine (a la The Boring Company, which is what meekGee is referencing) can't be removed from a tunnel that's being occupied behind it, nor can it back up to veer off at sharp angles to make a new tunnel. (A road-header is more flexible and might be a better option.)

MG seems to be picturing two TBMs in two parallel tunnels, one housing the habitat, one for the spoil-line + utilities + crew/parts-access, both somehow pressurised (**), with cross-links dug between them to allow the excavated spoil out of both tunnels to be shipped through one. In that case, if the cutting face hits unworkable material, then at least one of your TBMs is trapped by the habitat and can't be removed without complete disassembly. The other would require removal of the whole supporting infrastructure behind it before it would be backed out and moved to a new site. A slow and labour-intensive process.

Note, that's your "best case". Ie, you detect the problem before it causes actual damage.

"What's the worst that can happen" is if the tunnel collapses and destroys the TBMs, plus breaches the pressurised tunnels and kills your workers. (I assume the habitat is independently pressurised, but that has been glossed over.)


** (How do you remove spoil from a pressurised (sealed) tunnel? You'd need an airlock. The volume of material removed (by definition) equals at least the volume of the excavation. In practice it's much more, since loose material has a lower density than solid. Gravel is usually double rock. So twice the volume of spoil as tunnel volume, and since one tunnel is entirely for servicing the cutting faces, at least four times the habitable volume.

There seems to be a common image that once you dig a certain way in, you can close the door behind you and continue digging without access to the surface. As if the material dug out simply disappears (or shrinks drastically in volume.) The video-game version of mining.

The exception is if you a digging directly into ice as both your water "mine" and your habitat volume. You still need to pump the water to the industrial sites, but that's easier than transporting fresh cut gravel/dust.)
I put a bit more thought into it, but the discussion was about tunneling vs. surface habitats as a long term solution, not about how to tunnel.

Clearly tunneling for space on Mars is different than tunneling for transportation in a city on Earth.

Most everything you mention is solvable when you design the TBM.

--

A removable head is jot impossible to build, but it's also possible to go in a mile or two, curve around, and come back out.

Or, go under a hillside and emerge at the other end.

Or, just like you dug in from the surface, dig out to the surface.

--

You will need an airlock of course amyway, so what's the problem evacuating the tailings?  How fast is the machine moving again?

If you cam evacuate the tailings fast enough, you're in damn good shape.

--

Road headers will be necessary to cross connect parallel bores and do some local enlargements..  but I can't imagine they'll be anywhere near as efficient or fast as a cutting disc.

--

Cutting into a glacier is absolutely an option, if an appropriately thick and stable one is found.  There are ups and downs to it though..  rock is much stronger than ice...  And much more permanent. 

I can see both options used concurrently.

Overall I see building under ice or under rock as relatively similar, when compared to building structures on the surface.

You can add salt deposits as another variant.

--

LMT keeps thinking about Big Bertha, but I expect  TBC's machines to be very different.

Yes salt deposits are another variant and include a wide range of substances such as perchlorates, sulphates, chlorides and nitrates. There is also the possibility of CO2 clathrates / hydrates. We really need to know more about the subsurface structure before we start building habitats in it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 09/08/2020 10:10 am
A removable head is jot impossible to build

It's not just the cutting head. (Although I understand that in real systems, the head is the cause of a lot of issues with TBMs.) TBMs are a bit like trains, a series of carriages, which each carriage performing a task (plus passing on utilities to the carriages either side.) The cutting-head has a whole infrastructure behind it.

but it's also possible to go in a mile or two, curve around, and come back out.

I was replying to someone who asked "what's the worst that can happen [if you are digging blind]". I used your twin-tunnel model to illustrate my reasoning that it's harder than "just" pulling out and starting again.

You will need an airlock of course amyway, so what's the problem evacuating the tailings?  How fast is the machine moving again?

I don't know, how much are you digging out if you are housing 1000 people delivered every synod? Which I assume is what you are referring to when discussing Musk's ambition for a city on Mars.

Looking at actual TBM use (and no, not just Big Bertha), the entrance is constantly in use. Not just to remove spoil, although that it's own whole thing. There's also utilities that service the TBM. There's a constant flow of equipment to support the TBM. There's drilling equipment for the shoring system, there's grout and wall linings. TBMs aren't just the thing at the cutting face, they are a whole moving ballet of systems and support.

Road headers [won't] be anywhere near as efficient or fast as a cutting disc.

Which gets us back to "how fast is the machine moving". If you only require a single airlock to service the entire project (at the main tunnel-pressurisation entrance, I assume there will be smaller personnel airlocks. Plus airlocks for the hab which don't allow pass-through from the mine/dig. Etc etc) then you aren't digging very fast. Hence you aren't expanding each site very fast. In which case, do you need more than a single road-header? (Well, a couple for backup.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/08/2020 02:04 pm
A removable head is jot impossible to build

It's not just the cutting head. (Although I understand that in real systems, the head is the cause of a lot of issues with TBMs.) TBMs are a bit like trains, a series of carriages, which each carriage performing a task (plus passing on utilities to the carriages either side.) The cutting-head has a whole infrastructure behind it.

but it's also possible to go in a mile or two, curve around, and come back out.

I was replying to someone who asked "what's the worst that can happen [if you are digging blind]". I used your twin-tunnel model to illustrate my reasoning that it's harder than "just" pulling out and starting again.

You will need an airlock of course amyway, so what's the problem evacuating the tailings?  How fast is the machine moving again?

I don't know, how much are you digging out if you are housing 1000 people delivered every synod? Which I assume is what you are referring to when discussing Musk's ambition for a city on Mars.

Looking at actual TBM use (and no, not just Big Bertha), the entrance is constantly in use. Not just to remove spoil, although that it's own whole thing. There's also utilities that service the TBM. There's a constant flow of equipment to support the TBM. There's drilling equipment for the shoring system, there's grout and wall linings. TBMs aren't just the thing at the cutting face, they are a whole moving ballet of systems and support.

Road headers [won't] be anywhere near as efficient or fast as a cutting disc.

Which gets us back to "how fast is the machine moving". If you only require a single airlock to service the entire project (at the main tunnel-pressurisation entrance, I assume there will be smaller personnel airlocks. Plus airlocks for the hab which don't allow pass-through from the mine/dig. Etc etc) then you aren't digging very fast. Hence you aren't expanding each site very fast. In which case, do you need more than a single road-header? (Well, a couple for backup.)
There's no "just" or "simply"...  There never are.

But all those challenges are solvable, and the biggest factor remains, that when building by boring, the problem is scalable by volume.

Bore in, establish an airlock, and from that point structure and sealing have a very low marginal.cost.

The airlock is not a problem.  If the cross section is 10 m2, you need to move 1 m before sending out a 10 m3 trolley. 

If the Mars machine moves at 1 m and hour, that's enough to create 10 km of space per year.

.. and you're very likely to set up more than one airlock..  so I don't see that as being a problem.

Consider that a functioning colony has to have a high rate airlock anyway since vehicles will be moving in and out..  The linear nature of tunnels makes it natural to have a redundant multi-chambwr airlock, possibly with progressive pressure drops, so pump times are lower.

--

But 10 km, or even 1..  each year...  That's pretty enticing...  And that's from a single machine..
Title: Re: Envisioning Amazing Martian Habitats
Post by: livingjw on 09/08/2020 02:37 pm
Wouldn't you be leaking air all the time as you were boring? I assume this is porous rock. Are you pressurizing with CO2 or are you thinking of making it a breathable atmosphere during construction? A lot of wasted oxygen and nitrogen if its not perfectly sealed.

John
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 09/08/2020 02:48 pm
Wouldn't you be leaking air all the time as you were boring? I assume this is porous rock. Are you pressurizing with CO2 or are you thinking of making it a breathable atmosphere during construction? A lot of wasted oxygen and nitrogen if its not perfectly sealed.

John

I'm thinking they could have 1 atm pressure with co2 and just have oxygen masks for any people working in there. Let it leak and slowly plug the leaks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/08/2020 03:25 pm
Wouldn't you be leaking air all the time as you were boring? I assume this is porous rock. Are you pressurizing with CO2 or are you thinking of making it a breathable atmosphere during construction? A lot of wasted oxygen and nitrogen if its not perfectly sealed.

John
The CO2 pressurization /O2 masks trick will work, but I think you can bypass it.

Behind the cutting head there's some (10+?) meters of machine body, that form a close fit to the newly formed walls.

This is an ideal space to isolate, detect any seepage, and apply sealant,  so by the time the machine has moved on, the walls are sealed.

Diffusive seepage through the front wall will remain, but that can't be much.  And you can always make that area CO2 rich.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Frogstar_Robot on 09/08/2020 03:26 pm
"What's the worst that can happen" is if the tunnel collapses and destroys the TBMs, plus breaches the pressurised tunnels and kills your workers. (I assume the habitat is independently pressurised, but that has been glossed over.)

Ok, I am convinced :) Apart from anything else, accidently burying the boring machine requiring a complicated extraction is bad enough. It's clear that you need to be 99% sure of what you are tunneling into. And a survey would be required for other purposes anyway.

Building tunnels on Earth is a complex process, doing it on Mars amplifies the difficulty.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 09/08/2020 04:54 pm
Building tunnels on Earth is a complex process, doing it on Mars amplifies the difficulty.

At least you don't have to deal with water or methane bubbles.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RotoSequence on 09/08/2020 04:57 pm
Building tunnels on Earth is a complex process, doing it on Mars amplifies the difficulty.

At least you don't have to deal with water or methane bubbles.

There's always room for surprises. Clathrates that release their contents when heated are always possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Asteroza on 09/09/2020 12:39 am
Building tunnels on Earth is a complex process, doing it on Mars amplifies the difficulty.

At least you don't have to deal with water or methane bubbles.

There's always room for surprises. Clathrates that release their contents when heated are always possible.

At this rate, it sounds like practicing on siberian permafrost might be valid.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 09/09/2020 01:19 pm
Wouldn't you be leaking air all the time as you were boring? I assume this is porous rock.

I tried chasing this up the last could of times the topic came up. It's hard to correlate actual gas permeability figures from mining with "what happens when there's a near-vacuum on the other side". They are interested in fundamentally different issues and it makes translating non-obvious.

Anyone want to take a shot at it?



I'm thinking they could have 1 atm pressure with co2 and just have oxygen masks for any people working in there.

In that case, I'd keep the pressure closer to EVA levels. Run the "masks" on pure oxygen. This helps when the workers need to move back and forth between the tunnel and the surface. (Which, again going to Earth examples, is necessary and constant. Most of the "work" is happening outside the tunnel.)

["Masks" in scare-quotes because it would be a full head-covering, maybe a fully sealed suit. If the air around you is pure CO2, it takes only a slight leak around a face-mask to kill workers and face-masks are hard to properly seal. Positive pressure reduces inward leaks, but makes it harder to achieve a seal. Negative pressure makes it easier to create a seal, but any leaks you do have are worse. Still vastly easier than an EVA suit, but closer to an IVA suit or haz-mat bunny-suit.]
Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 09/09/2020 01:26 pm
Wouldn't you be leaking air all the time as you were boring? I assume this is porous rock.

I tried chasing this up the last could of times the topic came up. It's hard to correlate actual gas permeability figures from mining with "what happens when there's a near-vacuum on the other side". They are interested in fundamentally different issues and it makes translating non-obvious.

Anyone want to take a shot at it?



I'm thinking they could have 1 atm pressure with co2 and just have oxygen masks for any people working in there.

In that case, I'd keep the pressure closer to EVA levels. Run the "masks" on pure oxygen. This helps when the workers need to move back and forth between the tunnel and the surface. (Which, again going to Earth examples, is necessary and constant. Most of the "work" is happening outside the tunnel.)

["Masks" in scare-quotes because it would be a full head-covering, maybe a fully sealed suit. If the air around you is pure CO2, it takes only a slight leak around a face-mask to kill workers and face-masks are hard to properly seal. Positive pressure reduces inward leaks, but makes it harder to achieve a seal. Negative pressure makes it easier to create a seal, but any leaks you do have are worse. Still vastly easier than an EVA suit, but closer to an IVA suit or haz-mat bunny-suit.]

Well maybe N2 instead? There is a fair amount of N2 in the mars atmosphere.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 09/09/2020 05:04 pm
Wouldn't you be leaking air all the time as you were boring? I assume this is porous rock.

I tried chasing this up the last could of times the topic came up. It's hard to correlate actual gas permeability figures from mining with "what happens when there's a near-vacuum on the other side". They are interested in fundamentally different issues and it makes translating non-obvious.

Anyone want to take a shot at it?



I'm thinking they could have 1 atm pressure with co2 and just have oxygen masks for any people working in there.

In that case, I'd keep the pressure closer to EVA levels. Run the "masks" on pure oxygen. This helps when the workers need to move back and forth between the tunnel and the surface. (Which, again going to Earth examples, is necessary and constant. Most of the "work" is happening outside the tunnel.)

["Masks" in scare-quotes because it would be a full head-covering, maybe a fully sealed suit. If the air around you is pure CO2, it takes only a slight leak around a face-mask to kill workers and face-masks are hard to properly seal. Positive pressure reduces inward leaks, but makes it harder to achieve a seal. Negative pressure makes it easier to create a seal, but any leaks you do have are worse. Still vastly easier than an EVA suit, but closer to an IVA suit or haz-mat bunny-suit.]

I think even in worse case, applying sealant to a porous rock will be the least demanding in terms of mass/area.
Doubly so if some portion of the sealant is local material.

Once the tunnel gets deep, even if the rock is somewhat diffusive, the diffusion rate will be low - it's a gradient thing, and it's 1 ATM over however many meters of rock you have..  so the losses through any areas that haven't been sealed yet (e.g. the tunnel front wall) will decrease.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 09/09/2020 07:11 pm
@Paul451,

Liquid (or gas) permeability is measured in millidarcies, a dimensionless number often derived from gas flow permeability measurements. Rock is much more permeable to gas than to liquids due to viscosity, wetting etc. so a conversion is used in gas flow measurements to derive flow rates for liquids of interest. It also has some caveats with regards to grain size and Reynolds numbers.

One can draw analogy with gas pipelines - distribution lines run at 6psi, and leak all the time. The vast majority of leaks are left unattended.

Any simple liner is going to be subject to mechanical damage, chemical erosion, heat damage and so on. They'll start leaking eventually.

What is interesting is the interaction between a pressurised habitat leak and a near-vacuum atmosphere, with soil and rock involved. Air leaks into near-vacuum are supersonic, and they will fluidise the soil around them, turning them into scouring agents. Over time, I suppose they will wear channels through the rock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 09/20/2020 04:22 am
Related:  Shallow trenches can give unobtrusive ring gyms (https://forum.nasaspaceflight.com/index.php?topic=51387.msg2134194#msg2134194).
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/20/2020 12:39 pm
I dunno if it has been suggested before, but reading through a few comments here, regarding tunnels.

Everybody seems to think of tunnels as long and straight. That makes for a crappy habitat.

Assume you have a TBM and build one long straight tunnel, - you can only "branch" or make right-angled side tunnels with significant effort. And a long narrow tunnel is a crappy habitat because of exceedingly long pathways to get anywhere (you always have to traverse the tunnel lenghwise)

You could have many tunnels next to each other, but then you either need multiple TBMs or somehow turn the TBM around...

and everyone is thinking way too 2D and way too flat.  If you burrow underground you are in a 3D environment, and you can make full use of that to make a truly amazing underground hab:

Ingredients:
1. automated TBM that creates tunnel reinforcement out of the excavation material in situ.
2. A surface excavator to make vertical access shafts (optional, not really needed but might be useful)
3. Small scale mining equipment (jack-hammers, pick-axes)

Procedure:
1. You start boring a tunnel from the surface, the tunnel is curved as tight as a diameter your TBM allows and inclined downwards very slightly.
2. The curvature and incline is such that for a 180° turn the tunnel gets lower by 1 tunnel diameter
3. You relax the curvature so the radius of the circle your tunnel makes gets larger by 1 tunnel diameter every 180° (2 tunnel diameters every 360°)
4. After a full circle, you are 2 tunnel diameters down and 2 tunnel diameters further outside. This is close enough to make an access shaft that connects the two tunnels, so the excavation material can take this shortcut and doesn't have to go the long way round.
5. You make 5-10 full circles - digging a slightly expanding helix downwards. You connect the "rings" with ramps so people and material can move up and down between the "stories" of your underground habitat anywhere (basically build one or several staircases)

6. You now have the TBM at the lowest level. Expanding the habitat further, you stop going down, increase the diameter further, then incline upwards and make a second spiral "layer". After the transition, the tunnel is inclined upwards and it's diameter gets narrower with each turn, so the distance between the first layer and the second layer remains constant.
7. Once again cross connections are made between the "stories" but also horizontal connections between the "layers" at least every 180° to allow easy lateral traversal of both excavation material from the TBM and people.

8. You probably want to breach the surface once the TBM reaches the top. This allows replacing worn TBM parts and makes another surface access port+airlock (ideally 180° apart from the first one) for your growing habitat.

9. With the repaired TBM you make a 3rd layer back down, a 4th layer back up, etc... allowing the underground habitat to grow outwards continuously greatly increasing the habitable volume WITHOUT increasing travel distances for the inhabitants!!!

In the end, with only one TBM you can make a densely habitable 3d interconnected underground building with short paths, easy access and exit routes and easily removal of excavation material. The area covered by the habitat on the surface does not exceed a city block, while easily approaching a similar inhabitable density.

Thanks to the regular surface breaches, and the excavation ramps leading to the lowest level, supply even of bulky material is not an issue and does not interrupt regular operation.

If the TBM breaks, it is possible at any time to build a vertical access shaft from the surface directly to the TBM without intersecting already completed habitable and pressurized volume (or if, then at most one adjacent ring!), so the TBM can be disassembled, surfaced and repaired.

For safety reasons, In regular intervals (60° of the ring) as well as in all inter-story and inter-layer access ramps there should be a sealable bulkhead/fire door.
- This keeps the atmosphere inside in case of a breach.
- If a fire breaks out it can be isolated without spreading and the affected section can be vented to extinguish the fire.
Access to lower levels is still possible through the unaffected sections of the same ring and ramps.

I might should draw a picture of this, but I think the idea is clear.



Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 09/20/2020 01:48 pm
I might should draw a picture of this, but I think the idea is clear.
Yep, I think a picture or two would be good. I'm still trying to visualise how the layers are located with respect to each other.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/20/2020 02:06 pm
first layer:
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/20/2020 02:06 pm
2nd layer (here it gets slightly confusing)

note: this is one tunnel, it goes in on the insdie, goes 3 stories deep, then comes out again on the outside, always going clockwise, never intersecting.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/20/2020 02:12 pm
imagine the copper wire on the coil of an electric motor, except the coil is wider at the bottom than at the top.

so a better analogy would be the thread spindle on an overlocker:

Except you'd want to have the widening even less steep, probably around 45° - so the access tunnels in between floors do not get too steep.

In theory the same structure would also possible straight down, but if you have all the tunnels exactly over other tunnels - then all the inter-floor connections are straight up+down and I could imagine there might be issues with rock stability.


Edit: I have a feeling, this habitat layout - especially if large - would also be quite well suited if the martian colonists ever feel the urge to build a particle accelerator in their basement ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Frogstar_Robot on 09/20/2020 02:27 pm
I think I have the down spiral, I'm not sure about the "up" spiral.

The light blue, fuchsia tunnels are access tunnels at 45°.

Edit : ugh, forum threw away my post. Oh well, I guess you get the idea.

Added OpenSCAD source code and STL for completeness.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/20/2020 04:38 pm
I have given a lot of thought to tunnels and like you, CorvusCorax, I have also always envisaged some kind of network governed by the minimum tunnel curvature achievable by TBMs.

My ideas have revolved around shifted circles (see image), concentric cirles, circles branching left and right off a central axis (stem-and-leaf-like), etc, etc. There are very many exciting possibilities and I'd love for this thread to brainstorm about useful tunnel base configurations.

Title: Re: Envisioning Amazing Martian Habitats
Post by: rsdavis9 on 09/20/2020 07:23 pm
So in the tunnels for habitats.
What prevents a grid like layout.
First bore parallel tunnels.
The bore at 90 deg and go right through the first tunnels.

Would be hard for the boring machine to exit rock into no rock and back again?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/20/2020 08:15 pm
Assembling and setting up a TBM is a lot of work. You would have to do that every time you commence a new straight line.

I guess it would make sense to have as few exits to the surface as possible, since each of them would need to be sealed and include an airlock.
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 09/20/2020 09:25 pm
So in the tunnels for habitats.
What prevents a grid like layout.
First bore parallel tunnels.
The bore at 90 deg and go right through the first tunnels.

Would be hard for the boring machine to exit rock into no rock and back again?
I was thinking about this myself. We know that TBC TBMs can "porpoise" and so make tunnels shaped like this: "\______/"

If you can't (or don't want to) bore through the 90 deg tunnels you can basically weave them past each other at different levels and link vertically.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/20/2020 09:43 pm
I made a few more renders.

It's similar to Frogstar Robot, here is a habitat 4 "stories" deep and 4 layers wide - dug out with a single TBM plus some short distance crossdigging for access tunnels/ramps:


Picture 1: TMP goes down in a widening spiral (red) - after reaching the desired depth (4 circles) TPM digs up again (yellow circle)
Picture 2: TMP now goes up in a narrowing spiral (green) until 1 story beneath the top (2 circles) TPM then makes a widening spiral (blue circle)
Picture 3: Rinse and repeat. TPM goes down again in a widening spiral (red) then up slightly still widening

Access ramps between tunnels of the same layer can be dug anywhere, (here, every 90 degrees)
Horizontal access tunnels between layers can be dug at the 0° and 180° point. But sloped connections are possible almost anywhere.

Picture 4: Complete habitat.

Picture 5: cutout

Picture 6: negative cutout

Also added: STL file



Picture 4: Complete habitat


https://www.tinkercad.com/embed/6ojjTtUFwq6?editbtn=1
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/20/2020 11:13 pm
The cool thing with this layout is. You can grow it arbitrarily in all 3 dimensions. Instead of 4 stories and 4 layers, you could easily extend it to 20 stories and 20 layers.

Since the circles are still large compared to the inter-circle spacing, this would still less than triple the maximum travel distance between any 2 points within the habitat - making use of the minimum viable number of intersections. It would increase the depth 5 fold, but the area covered by the habitat would probably increase by less than factor 4.

Yet, you'd get 25 times the habitable volume of of the 4x4 habitat depicted above, or 400 times the habitat volume of a single circular tunnel.

Since the habitat can keep growing both outwards and downwards over time, this habitat would probably scale very well - from an initial habitat tunnel for a few dozen Astronauts + utilities, you could keep building it up to the scale of a complete underground city with thousands of people.

At any point in the construction the TBM would always be in the outermost layer, and you could always build a vertical access shaft if the TBM needs to be replaced - without affecting the already built colony. The TBM also naturally "surfaces" every 2nd layer, which is good for planned maintenance/replacement if needed.

Edit: I should mention that this habitat layout allows to operate both the TPM un-pressurized (exposed to martian atomsphere) - as well as an completely un-pressurized travel path for the excavation material - so the material does not have to be transported through airlocks at any time (which would slow things down and waste precious atmosphere)

For this to be possible, you would need airlocks - or at least bulkheads - around some of the  intersections and crossings (those dedicated for excavation material transport), but sectioning the habitat with bulkheads is a good idea anyway for fire and other hazard mitigation.

Waste material management:

1. Begin of operations. During the first spiral revolution, the waste material is transported through the main tunnel, the habitat is not yet usable.

2. After the first revolution and installation of an access ramp near the entrance to get to the second winding, a bulkhead is placed in the tunnel bottom next to the access ramp, while an airlock is installed at the top - waste material is now transported via the access ramp, while the remainder of the habitat is pressurized and unaffected by construction

3. After the second revolution, the previously completed spiral ring is sealed off with bulkheads and a pressurized access ramp is constructed to connect the habitable volume.  construction on the 3rd spiral ring continues unpressurized using the unpressurized access ramps.

4. once the habitat has multiple layers, only the outermost layer needs seals around the access ramps, while the top level floor needs seals around the horizontal access tunnel that is adjacent to the habitat entrance. these access ramps and horizontal access tunnels are used for excavation material transfer. all other rings (below and inwards) allow uninterrupted habitable volume at all times.

It's probably a good idea to leave the bulkheads in place with self-sealing emergency doors, to isolate parts of the habitat in case of a fire or depressurization. (similar to how it's done on ocean vessels)



Title: Re: Envisioning Amazing Martian Habitats
Post by: _MECO on 09/21/2020 05:11 am
The cool thing with this layout is. You can grow it arbitrarily in all 3 dimensions. Instead of 4 stories and 4 layers, you could easily extend it to 20 stories and 20 layers.

Since the circles are still large compared to the inter-circle spacing, this would still less than triple the maximum travel distance between any 2 points within the habitat - making use of the minimum viable number of intersections. It would increase the depth 5 fold, but the area covered by the habitat would probably increase by less than factor 4.

Yet, you'd get 25 times the habitable volume of of the 4x4 habitat depicted above, or 400 times the habitat volume of a single circular tunnel.

Since the habitat can keep growing both outwards and downwards over time, this habitat would probably scale very well - from an initial habitat tunnel for a few dozen Astronauts + utilities, you could keep building it up to the scale of a complete underground city with thousands of people.

At any point in the construction the TBM would always be in the outermost layer, and you could always build a vertical access shaft if the TBM needs to be replaced - without affecting the already built colony. The TBM also naturally "surfaces" every 2nd layer, which is good for planned maintenance/replacement if needed.

Edit: I should mention that this habitat layout allows to operate both the TPM un-pressurized (exposed to martian atomsphere) - as well as an completely un-pressurized travel path for the excavation material - so the material does not have to be transported through airlocks at any time (which would slow things down and waste precious atmosphere)

For this to be possible, you would need airlocks - or at least bulkheads - around some of the  intersections and crossings (those dedicated for excavation material transport), but sectioning the habitat with bulkheads is a good idea anyway for fire and other hazard mitigation.

Waste material management:

1. Begin of operations. During the first spiral revolution, the waste material is transported through the main tunnel, the habitat is not yet usable.

2. After the first revolution and installation of an access ramp near the entrance to get to the second winding, a bulkhead is placed in the tunnel bottom next to the access ramp, while an airlock is installed at the top - waste material is now transported via the access ramp, while the remainder of the habitat is pressurized and unaffected by construction

3. After the second revolution, the previously completed spiral ring is sealed off with bulkheads and a pressurized access ramp is constructed to connect the habitable volume.  construction on the 3rd spiral ring continues unpressurized using the unpressurized access ramps.

4. once the habitat has multiple layers, only the outermost layer needs seals around the access ramps, while the top level floor needs seals around the horizontal access tunnel that is adjacent to the habitat entrance. these access ramps and horizontal access tunnels are used for excavation material transfer. all other rings (below and inwards) allow uninterrupted habitable volume at all times.

It's probably a good idea to leave the bulkheads in place with self-sealing emergency doors, to isolate parts of the habitat in case of a fire or depressurization. (similar to how it's done on ocean vessels)

Isn't it going to be hard to excavate tunnels immediately at right angles to your primary tunnel? I would imagine the machine you're using to bore these tunnels can't exactly turn on a dime. And why go down when you can go out? There would be more surface access that way and you wouldn't need to worry about boring tunnels on a grade.

Unrelated note, maybe we should start taking a look at which blasting explosives can be synthesized using in-situ Martian resources. There's already going to be a drive to locate and mine Nitrogen-bearing minerals for growing food and oxygen in greenhouses. Prior to useful mining it may be necessary to import nitrogen or otherwise resort to energetic materials which do not use Nitrogen.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 09/21/2020 05:48 am
Unrelated note, maybe we should start taking a look at which blasting explosives can be synthesized using in-situ Martian resources. There's already going to be a drive to locate and mine Nitrogen-bearing minerals for growing food and oxygen in greenhouses. Prior to useful mining it may be necessary to import nitrogen or otherwise resort to energetic materials which do not use Nitrogen.

On Mars the atmosphere is 2.6% nitrogen. It will be easy to get when extracting CO2 to use in propellant production. Compress and liquefy. The various gasses will turn liquid at different temperatures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 09/21/2020 07:56 am
Isn't it going to be hard to excavate tunnels immediately at right angles to your primary tunnel? I would imagine the machine you're using to bore these tunnels can't exactly turn on a dime. And why go down when you can go out? There would be more surface access that way and you wouldn't need to worry about boring tunnels on a grade.
As I understand it, the suggestion is that only the main tunnel uses the tunnel boring machine. The cross-connections are all short and dug manually. The whole basis for the idea is that you don't need to do sharp turns with your TBM.

As for going vertically as well as horizontally, why wouldn't you? Boring on a grade isn't at all hard, and it massively increases the density of the space you create.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/21/2020 02:34 pm
Isn't it going to be hard to excavate tunnels immediately at right angles to your primary tunnel? I would imagine the machine you're using to bore these tunnels can't exactly turn on a dime. And why go down when you can go out? There would be more surface access that way and you wouldn't need to worry about boring tunnels on a grade.
As I understand it, the suggestion is that only the main tunnel uses the tunnel boring machine. The cross-connections are all short and dug manually. The whole basis for the idea is that you don't need to do sharp turns with your TBM.

As for going vertically as well as horizontally, why wouldn't you? Boring on a grade isn't at all hard, and it massively increases the density of the space you create.

Exactly this. The access ramps and connecting tunnels would be dug infrequently, one at a time, whenever a new ring is complete. These connections are so short they can be dug with manual equipment (with a pickaxe if need be) or by a multi purpose mining robot that has some limited excavation ability - a TBM would be overkill - a typical TBM would be longer than the tunnel it needs to make ;)





Title: Re: Envisioning Amazing Martian Habitats
Post by: Ice on 09/21/2020 02:44 pm
SpaceX Mars Base Alpha concept by Sotiris (https://www.humanmars.net/2020/09/spacex-mars-base-alpha-concept-by.html)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 09/21/2020 03:23 pm
Isn't it going to be hard to excavate tunnels immediately at right angles to your primary tunnel? I would imagine the machine you're using to bore these tunnels can't exactly turn on a dime. And why go down when you can go out? There would be more surface access that way and you wouldn't need to worry about boring tunnels on a grade.
As I understand it, the suggestion is that only the main tunnel uses the tunnel boring machine. The cross-connections are all short and dug manually. The whole basis for the idea is that you don't need to do sharp turns with your TBM.

As for going vertically as well as horizontally, why wouldn't you? Boring on a grade isn't at all hard, and it massively increases the density of the space you create.

Exactly this. The access ramps and connecting tunnels would be dug infrequently, one at a time, whenever a new ring is complete. These connections are so short they can be dug with manual equipment (with a pickaxe if need be) or by a multi purpose mining robot that has some limited excavation ability - a TBM would be overkill - a typical TBM would be longer than the tunnel it needs to make ;)
Although the spiral is a great idea, feasibility will depend on the type of rock available.  If the rock is sound, great, if the rock is friable and structural lining is required, then the side passages will require lining and the connection to the main tunnel may be difficult.  It might then be better to make smaller side tunnels, not of the full tunnel diameter, to simplify construction.  If smaller tubes are used, then these can be designed not to transmit strain to the main tunnel walls, although these would need specific reinforcement around the openings.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Coastal Ron on 09/21/2020 03:27 pm
Isn't it going to be hard to excavate tunnels immediately at right angles to your primary tunnel? I would imagine the machine you're using to bore these tunnels can't exactly turn on a dime. And why go down when you can go out? There would be more surface access that way and you wouldn't need to worry about boring tunnels on a grade.
As I understand it, the suggestion is that only the main tunnel uses the tunnel boring machine. The cross-connections are all short and dug manually. The whole basis for the idea is that you don't need to do sharp turns with your TBM.

As for going vertically as well as horizontally, why wouldn't you? Boring on a grade isn't at all hard, and it massively increases the density of the space you create.

Exactly this. The access ramps and connecting tunnels would be dug infrequently, one at a time, whenever a new ring is complete. These connections are so short they can be dug with manual equipment (with a pickaxe if need be) or by a multi purpose mining robot that has some limited excavation ability - a TBM would be overkill - a typical TBM would be longer than the tunnel it needs to make ;)

While building tunnels using Elon Musk's The Bore Company equipment is likely a given, tunnels are usually just for transportation, not for work spaces or living spaces. Which means we should expect other types of excavation equipment to make its way to Mars, including (from Mining Weekly (https://www.miningweekly.com/article/a-guide-on-mining-equipment-used-in-the-mining-industry-2019-05-31/rep_id:3650)):

- Mining drills
- Blasting tools
- Earth movers
- Crushing equipment
- Screening equipment
- Feeding, conveying, and analysis equipment

I would imagine that tunnel boring would be just the start of building underground facilities, and the process of boring tunnels could provide needed material for all sorts of other activities on the surface, and for ISRU.

My $0.02
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/21/2020 04:40 pm
It is true that tunnels are not *usually* done for work or living spaces, but doing a base on Mars is not a usual activity either. TBMs offer by far the most bang for the buck when it comes to creating interior spaces for a given tonnage brought to Mars. I suspect that circumstance will govern the initial period of colonization and that settlers will have to work with the it, since other methods of creating interior space are much less cost-effective.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Greg Hullender on 09/21/2020 05:03 pm
Could any of this feasibly be tested on the moon? The moon is a lot closer, and it sure would be nice to find problems there first, if at all possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RotoSequence on 09/21/2020 05:06 pm
It is true that tunnels are not *usually* done for work or living spaces, but doing a base on Mars is not a usual activity either. TBMs offer by far the most bang for the buck when it comes to creating interior spaces for a given tonnage brought to Mars. I suspect that circumstance will govern the initial period of colonization and that settlers will have to work with the it, since other methods of creating interior space are much less cost-effective.

They're efficient for volume, I'll give you that, but I'm not sold on those savings being intact once you line the walls with air and liquid sealant and insulate it. The depth of the permafrost, given Mars' extended period of time as a cold and low atmosphere dust ball, could be kilometers deep before it gives way to subsurface heating.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 09/21/2020 05:44 pm
Could any of this feasibly be tested on the moon? The moon is a lot closer, and it sure would be nice to find problems there first, if at all possible.
No. the TBM will need a working fluid, and that's WAY too scarce on the Moon. Mars can use CO2 easily.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Coastal Ron on 09/21/2020 08:28 pm
It is true that tunnels are not *usually* done for work or living spaces, but doing a base on Mars is not a usual activity either. TBMs offer by far the most bang for the buck when it comes to creating interior spaces for a given tonnage brought to Mars. I suspect that circumstance will govern the initial period of colonization and that settlers will have to work with the it, since other methods of creating interior space are much less cost-effective.

High math is not my specialty, but I think there are math theorems that would help explain this. Unfortunately I'll have to use my typing skills...  :o

Let's say you have one tunnel, with one entrance. In order to access the deepest part of the tunnel you need to have a pathway, and due to the round shape of a tunnel, the pathway would likely be running down the middle of the tunnel, with some distance off the floor. Such an arrangement allows for some storage, but living space is more like a train than an apartment.

Let's say you have two tunnels running in parallel, and short tunnels that connect them periodically. Now one tunnel can be for transportation, and the other tunnel can be for storage and living space. Still not ideal, since the number of connecting tunnels determines the density of the storage and living spaces.

Now let's say you have three tunnels running in parallel, with short connecting tunnels between the middle tunnel and the two outer ones. The middle one is the transportation tunnel, and the outer two are for storage and living space. Still the same packing issues regarding the number of access tunnels, but now the efficiency of the transportation tunnel is doubled.

Those access tunnels are really important, since they are what allow you to double, triple, or greatly expand not only the usable space, but the safety too, since you create more escape routes. Ideally you should have some large grid of tunnels, which then allow you to excavate the space in between some of those tunnels to create large indoor areas. That is what I think their goal will be, large indoor areas that started out as a series of tunnels.

My $0.02
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/21/2020 10:21 pm
I absolutely agree that parallel tunnels will be a great configuration, which is why I posted the "shifted circles" graphic a page back.

As for large indoor areas, absolutely, if the rock will hold up. Subtropolis comes to mind: https://en.wikipedia.org/wiki/SubTropolis

I have visited several Maginot line forts: they give a really good impression of how a Mars underground base could look.
Title: Re: Envisioning Amazing Martian Habitats
Post by: CorvusCorax on 09/21/2020 11:21 pm
One thing that might be a factor is fully-autonomous construction.

If you send equipment up there that basically finished the habitat on its own before the people get there to use it, this would be optimal.

I think a TBM has a good chance of doing so, if it can make the "compressed rubble-stone" out of the excavation material in situ, like Boring Company wants to do.

Other mining equipment is often too manual-labor intensive and hasn't reached the level of automation to do this autonomously until needed.

But you could of course make a spiral-tunnel-habitat robotically with a TBM and just let the settlers dig the connection tunnels and ramps on arrival, greatly reducing bootstrap-time.

Another bootstrapping option is large above-surface habitats that are landed "as is" (habitat starships)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 09/22/2020 08:12 am
One thing that might be a factor is fully-autonomous construction.

If you send equipment up there that basically finished the habitat on its own before the people get there to use it, this would be optimal.

I think a TBM has a good chance of doing so, if it can make the "compressed rubble-stone" out of the excavation material in situ, like Boring Company wants to do.

Other mining equipment is often too manual-labor intensive and hasn't reached the level of automation to do this autonomously until needed.

But you could of course make a spiral-tunnel-habitat robotically with a TBM and just let the settlers dig the connection tunnels and ramps on arrival, greatly reducing bootstrap-time.

Another bootstrapping option is large above-surface habitats that are landed "as is" (habitat starships)
They will probably end up with a mixture of methods. Starship is OK for the initial exploration / pioneer missions, but they will increasingly need a radiation safe habitat from which to operate as a refuge and as a location for remote operation of machinery. The initial surface habitat will probably involve inflatable units carried by Starship and then covered with regolith. An automated pressed regolith block machine using biolith mortar would be very helpful in building the radiation protection shell for this initial structure.

Once that is in place they can experiment with under ground construction for a bigger habitat, but we should not under estimate the challenges they will face due to the novel nature of the martian environment. It might take a long time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/23/2020 11:09 pm
I agree: that sounds like a very plausible order of habs. Starship - Inflatable surface hab - Tunnels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 09/24/2020 10:40 pm
I agree: that sounds like a very plausible order of habs. Starship - Inflatable surface hab - Tunnels.

It seems NASA agrees. These correspond closely to Cohen and Kennedy's classification system for surface habitats.

https://www.researchgate.net/profile/Marc_Cohen5/publication/23894764_Habitats_and_Surface_Construction_Technology_and_Development_Roadmap/links/563ba10808ae405111a7703c/Habitats-and-Surface-Construction-Technology-and-Development-Roadmap.pdf

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 09/25/2020 07:55 pm
And thus the 100-page controversy between different hab concepts was ended :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 09/26/2020 04:32 am
You think ???
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/06/2020 06:33 am
And thus the 100-page controversy between different hab concepts was ended :-)
Not at all.

Im 100% convinced that tunnels are a terrible way to build habitats on Mars.

Most people want to go underground to solve for radiation. But radiation is easy to solve on the surface.
Building on the surface is better for a host of reasons.
- Can service and connect buildings easier after construction
- Easier access to the surface
- Can utilize natural light
- Surface views
- Simpler construction on surface
- Larger volumes can be built on the surface
- Building can be built from multiple directions at once. A tunnel is mostly a 1 dimensional element.
- Less unknowns
- Dont need to dump massive volumes of soil all over the place. Can use cut and fill on the surface.
- Tunnels still need huge amounts of reinforced concrete panels. There is no saving on material.
- You cant do any interior work until your done with the whole tunnel, as material needs to flow through the whole tunnel as you dig. Means, total construction time will be much slower.

If your using the Boring company as a reference, your in the wrong direction.
Tunnels are only 3.8m in diameter. This is tiny.
They are only tunneling where there is soft soil. Rock impact tunneling speed by a lot.

Tunneling may be used for some habitats. But your not putting 1million people underground.


Title: Re: Envisioning Amazing Martian Habitats
Post by: Frogstar_Robot on 10/06/2020 07:52 am
And thus the 100-page controversy between different hab concepts was ended :-)
Not at all.

Im 100% convinced that tunnels are a terrible way to build habitats on Mars.

Most people want to go underground to solve for radiation. But radiation is easy to solve on the surface.

Well, no. It is not easy to solve. That is why people are looking at lava tubes, tunnels etc. Tunneling may be a terrible way to build habitats on Mars, but it may be the least terrible way.

Building anything in an environment with no atmosphere, large temperature swings, high radiation etc is going to be difficult.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/06/2020 08:05 am
Well, no. It is not easy to solve. That is why people are looking at lava tubes, tunnels etc. Tunneling may be a terrible way to build habitats on Mars, but it may be the least terrible way.

Building anything in an environment with no atmosphere, large temperature swings, high radiation etc is going to be difficult.
All these things need to be solved.

Im simply arguing that solving them in tunnels will be worse than solving them on the surface.

If we cant build on the surface, then Mars will never have more than a little outpost. Tunnels are terrible, that's why we only use them when we are out of options on earth.
I dont see it being all that much different on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Frogstar_Robot on 10/06/2020 08:19 am
Well, no. It is not easy to solve. That is why people are looking at lava tubes, tunnels etc. Tunneling may be a terrible way to build habitats on Mars, but it may be the least terrible way.

Building anything in an environment with no atmosphere, large temperature swings, high radiation etc is going to be difficult.
All these things need to be solved.

Im simply arguing that solving them in tunnels will be worse than solving them on the surface.

If we cant build on the surface, then Mars will never have more than a little outpost.

That may be true. I am not expecting more than a little outpost for the foreseeable future, something like an Antarctic research station.

Quote
Tunnels are terrible, that's why we only use them when we are out of options on earth.
I dont see it being all that much different on Mars.

The balance of the equation is completely different on Mars, because the surface of Earth is a very good place to build things.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 10/06/2020 08:25 am
And thus the 100-page controversy between different hab concepts was ended :-)
Not at all.

Im 100% convinced that tunnels are a terrible way to build habitats on Mars.

Most people want to go underground to solve for radiation. But radiation is easy to solve on the surface.
Building on the surface is better for a host of reasons.
- Can service and connect buildings easier after construction
- Easier access to the surface
- Can utilize natural light
- Surface views
- Simpler construction on surface
- Larger volumes can be built on the surface
- Building can be built from multiple directions at once. A tunnel is mostly a 1 dimensional element.
- Less unknowns
- Dont need to dump massive volumes of soil all over the place. Can use cut and fill on the surface.
- Tunnels still need huge amounts of reinforced concrete panels. There is no saving on material.
- You cant do any interior work until your done with the whole tunnel, as material needs to flow through the whole tunnel as you dig. Means, total construction time will be much slower.

If your using the Boring company as a reference, your in the wrong direction.
Tunnels are only 3.8m in diameter. This is tiny.
They are only tunneling where there is soft soil. Rock impact tunneling speed by a lot.

Tunneling may be used for some habitats. But your not putting 1million people underground.
I would agree with a lot of that, but would add two things, firstly building on the surface leaves the crew / inhabitants exposed to higher levels of GCR which is the main reason for going underground despite the disadvantages. How do you propose to fully protect them from such radiation without incurring the things that you point out? Cut and cover also involves a number of problems that you mention and also suffers from more serious pressurization issues with large diameter structures. 

Secondly there are various means of excavating below the surface which include tunnelling, but are not limited to tunnelling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/06/2020 08:26 am
The balance of the equation is completely different on Mars, because the surface of Earth is a very good place to build things.
Why is the surface of Mars not a good place to build things?
We can build radiation shielded structures on Mars using 2000 year old technology.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/06/2020 08:39 am
I would agree with a lot of that, but would add two things, firstly building on the surface leaves the crew / inhabitants exposed to higher levels of GCR which is the main reason for going underground despite the disadvantages. How do you propose to fully protect them from such radiation without incurring the things that you point out? Cut and cover also involves a number of problems that you mention and also suffers from more serious pressurization issues with large diameter structures. 

Secondly there are various means of excavating below the surface which include tunnelling, but are not limited to tunnelling.
You dont need to eliminate radiation, you need to reduce it to acceptable levels.
You can live on the surface on Mars with no radiation protection and still have lower levels of Cancer than a typical smoker on earth.
Cut and cover is just one way to do it.

Better is to add water on the roofs of the structures. Water is great at blocking radiation, and can be used to cool power generating systems. Can even use water for fish farming, which then integrates with aquaculture for general food production.
One step further, if you have clear roofs with 4m of water on top you have natural lighting inside the habitats at far greater levels than the massive amount of lighting that will be required underground.
For reference, if you have 4m of water overhead on Mars, you will still have more than 10-20x the light than a typical office or residential lit area. This has long term effects on child development. And will have physiological effects too.
You can grow plants in surface buildings, where as tunnels wont allow much vegetation as heat will become a huge issue.

We are just not used to building inflatable structures. Building on Mars will require a paradigm shift in thinking.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Frogstar_Robot on 10/06/2020 09:11 am
The balance of the equation is completely different on Mars, because the surface of Earth is a very good place to build things.
Why is the surface of Mars not a good place to build things?
We can build radiation shielded structures on Mars using 2000 year old technology.

Right, pyramids on Mars. No problem :)

Image credit : https://trinfinity8.com/nasa-discovers-pyramid-on-mars/
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/06/2020 04:26 pm
The balance of the equation is completely different on Mars, because the surface of Earth is a very good place to build things.
Why is the surface of Mars not a good place to build things?
We can build radiation shielded structures on Mars using 2000 year old technology.

Right, pyramids on Mars. No problem :)

Image credit : https://trinfinity8.com/nasa-discovers-pyramid-on-mars/
Well, if they are already there, whats the problem? Lets light the rockets and go!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/06/2020 05:12 pm
[snip]

Building on the surface is better for a host of reasons.
- Can service... buildings easier after construction

Depends on how they're designed. Obviously if you know you won't have access to the outer surface you lay things out a little differently.

- Can... connect buildings easier after construction

Fundamentally connecting is just digging a tunnel vs. building a pressurized structure. So either building a tunnel is harder (in which case... isn't that your whole argument?), or this point is incorrect.

This bullet point boils down to "tunneling is harder because tunneling is harder." Sorry, no freebies mate. ;)

- Easier access to the surface
- Can utilize natural light
- Surface views

These are the only real points, imo. And honestly these are relatively minor.

- Simpler construction on surface
- Larger volumes can be built on the surface

More question-begging. "Tunneling is harder because tunneling is harder."

- Building can be built from multiple directions at once. A tunnel is mostly a 1 dimensional element.

See the points upthread about various tunneling tech.

- Less unknowns

Pretty vague. Also technically should be "fewer unknowns." ;)

- Dont need to dump massive volumes of soil all over the place. Can use cut and fill on the surface.

Moving large volumes of soil is small potatoes compared to manufacturing a highly reliable pressure vessel, either carrying it from Earth ($$$) or building it on Mars ($$$ plus "unknowns").

- Tunnels still need huge amounts of reinforced concrete panels. There is no saving on material.

"X uses material. Y uses material. Therefore X uses the same amount of material as Y."

I would re-check the underlying logic here. It looks like you skipped the step where you actually quantitatively compare the amounts of material (and more importantly, the total cost of material) used in both cases.

- You cant do any interior work until your done with the whole tunnel, as material needs to flow through the whole tunnel as you dig. Means, total construction time will be much slower.

There are various proposed ways to close off finished sections while continuing construction in other segments. A recent example: https://forum.nasaspaceflight.com/index.php?topic=41427.msg2134250#msg2134250

If your using the Boring company as a reference, your in the wrong direction.
Tunnels are only 3.8m in diameter. This is tiny.
They are only tunneling where there is soft soil. Rock impact tunneling speed by a lot.

Yep, I think people making a 1-to-1 leap from Boring tech to Mars habs are going a bit too far.



The balance of the equation is completely different on Mars, because the surface of Earth is a very good place to build things.
Why is the surface of Mars not a good place to build things?
We can build radiation shielded structures on Mars using 2000 year old technology.

Why is the surface of Mars a good place to build things? You're the one making the positive claim.

"Because that how it is on Earth," is just reasoning by analogy.

You can live on the surface on Mars with no radiation protection and still have lower levels of Cancer than a typical smoker on earth.

Comparing to literally the most deadly product in the world isn't great. That's like saying, "don't worry, your risk of death is lower than a typical base-jumper on Earth!"



Cut and cover is just one way to do it.

Better is to add water on the roofs of the structures. Water is great at blocking radiation, and can be used to cool power generating systems. Can even use water for fish farming, which then integrates with aquaculture for general food production.

Do the math on that proposal. I think you'll find that the per-person volume needed for radiation shielding vastly out-paces the per-person volume needed for fish farming. So most of your water roof will be purpose-built, and if you're dedicating water solely for that purpose it's going to be expensive.

Ditto for re-using the pool as cooling water. The great thing about using eg a river for cooling water is that it flows away. In your proposal the heat would just build up in the pool, getting hotter and hotter until it boils. Sure you'll reject some heat off the roof surface, but you could accomplish the exact same performance with just a simple flat-plate radiator. So the synergy of combining radiation shielding and cooling pond isn't really providing much "for free."

One step further, if you have clear roofs with 4m of water on top you have natural lighting inside the habitats at far greater levels than the massive amount of lighting that will be required underground.
For reference, if you have 4m of water overhead on Mars, you will still have more than 10-20x the light than a typical office or residential lit area. This has long term effects on child development. And will have physiological effects too.
You can grow plants in surface buildings, where as tunnels wont allow much vegetation as heat will become a huge issue.

With LEDs, lighting isn't a big power drain.

As for children's eye development, clearly being around typical lighting for most of the time is fine. Providing a brightly-lit play area is trivial.

We are just not used to building inflatable structures. Building on Mars will require a paradigm shift in thinking.

On this, my friend, we agree.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/06/2020 06:24 pm
Fundamentally connecting is just digging a tunnel vs. building a pressurized structure. So either building a tunnel is harder (in which case... isn't that your whole argument?), or this point is incorrect.
No, it really is not.
If you have two segments of tunnel that is currently occupied. How do you connect the two if you cant get a TBM in either tunnel? You now need to dig from either side, removing soil along your entire tunnel length.
There are major technical differences. This is more akin to your neighbour needing to extend his bedroom, but needs to move all the building material through your front door.

Quote
Quote from: MaNaeSWolf on Today at 06:33 am
- Easier access to the surface
- Can utilize natural light
- Surface views
These are the only real points, imo. And honestly these are relatively minor.
These points are only minor if your accepting a research base only. But if your "Envisioning Amazing Martian Habitats", these are major points.

Pretty vague. Also technically should be "fewer unknowns.
You got me on "fewer unknowns" :)
But in construction, we add a lot of space for unknowns underground, because it can seriously throw plans off course. If you need to blast every 100m of digging, your gonna have a bad time.

I would re-check the underlying logic here. It looks like you skipped the step where you actually quantitatively compare the amounts of material (and more importantly, the total cost of material) used in both cases.
Have done some math. If you want to tunnel on Mars, you will need steel manufacturing and concrete manufacturing. But you also need to import massive TBM. Change the imported mass from TBM to more mining equipment and your steel becomes cheaper. But dont actually need any concrete. There are better ways to make cheap tensile material on Mars than using steel though. If you have the ability to built underground, you have the ability to build on the surface. Not necessarily the other way round though.

Comparing to literally the most deadly product in the world isn't great. That's like saying, "don't worry, your risk of death is lower than a typical base-jumper on Earth!"
Being alive gives you a 20% chance of dying of cancer. Being a smoker increases that by 4%, being on Mars about 2-3%. Living under 4m of water will bring it to earth levels again. Infact, if your shielded for 18 hours a day, you can spend the rest of the day outside with no noticeable increase of Cancer at all. Base jumpers on the other hand have a 1.7% chance of dying per year of activity. Id rather be on Mars.

Do the math on that proposal. I think you'll find that the per-person volume needed for radiation shielding vastly out-paces the per-person volume needed for fish farming. So most of your water roof will be purpose-built, and if you're dedicating water solely for that purpose it's going to be expensive.

Ditto for re-using the pool as cooling water. The great thing about using eg a river for cooling water is that it flows away. In your proposal the heat would just build up in the pool, getting hotter and hotter until it boils. Sure you'll reject some heat off the roof surface, but you could accomplish the exact same performance with just a simple flat-plate radiator. So the synergy of combining radiation shielding and cooling pond isn't really providing much "for free."
Your actually right on the first part! You can feed about 30% of all your calorie intake with just fish farms.

The water on the roof is for radiation proofing, but doubles for other things too. Including recreational water skiing or what ever. The water would need to be covered to stop sublimation (also why you can go ski on it). The reason why you use water is because its excellent at carrying heat, and easy to move about.It iss just a place with a large surface area to dump heat. Obviously this will need to be controlled. But your still radiating a few 100w/m2 by doing this.

With LEDs, lighting isn't a big power drain.

As for children's eye development, clearly being around typical lighting for most of the time is fine. Providing a brightly-lit play area is trivial.
This is underrated.
Research suggest that children that dont get daily exposure to about 15 000 lux start to suffer a host of issues ranging from eye development to MS to cognitive issues. The average well lit office (higher than a regular home) is about 500 lux.
If you have a window in a room, chances are your getting well over 10 000 lux during the day. Step outside on a cloudy day, you have about 40 000 lux. Mars has no clouds, so your typical surface has about 60 000 Lux, or about 45000 lux under 5m of water.

Overall, there are lots of issues that will need to be solved when people go to Mars. Solving the problem technically will however be pointless if you don't solve it for humans. Very few people are made out to be miners and submariners.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/06/2020 09:06 pm
Fundamentally connecting is just digging a tunnel vs. building a pressurized structure. So either building a tunnel is harder (in which case... isn't that your whole argument?), or this point is incorrect.
No, it really is not.
If you have two segments of tunnel that is currently occupied. How do you connect the two if you cant get a TBM in either tunnel?

You're assuming that tunneling = TBM. But there are many ways to tunnel.

You now need to dig from either side, removing soil along your entire tunnel length.
There are major technical differences. This is more akin to your neighbour needing to extend his bedroom, but needs to move all the building material through your front door.

Again, this logistics challenge is true of any tunneling operation. "Tunneling is hard because tunneling is hard."


Quote
Quote from: MaNaeSWolf on Today at 06:33 am
- Easier access to the surface
- Can utilize natural light
- Surface views
These are the only real points, imo. And honestly these are relatively minor.
These points are only minor if your [sic] accepting a research base only. But if your [sic] "Envisioning Amazing Martian Habitats", these are major points.

I don't accept this assertion. It definitionally can't be "amazing" using artificial sunlight indoors? Really?

And obviously tunnels will have access to the surface (presumably including views), because how else would you enter the tunnel? All you're saying is that it might possibly be more expensive to build per-entrance (hard numbers are still forthcoming on this point). Even if it we were to demonstrate that this is true, if building underground saves on per-volume costs then underground living could still be cheaper overall.


Pretty vague. Also technically should be "fewer unknowns.
You got me on "fewer unknowns" :)
But in construction, we add a lot of space for unknowns underground, because it can seriously throw plans off course. If you need to blast every 100m of digging, your [sic] gonna have a bad time.

When it comes to building on Mars, we've got nothing but unknowns. This is true for above-ground construction too. How can you say for sure which one is "more unknown" than the other? This is a hard problem to answer, and (setting aside reasoning by analogy) it's not clear that your conclusion is based on anything more than gut instinct.


I would re-check the underlying logic here. It looks like you skipped the step where you actually quantitatively compare the amounts of material (and more importantly, the total cost of material) used in both cases.
Have done some math.

Can we see your math?


If you want to tunnel on Mars, you will need steel manufacturing and concrete manufacturing.

Maybe so, maybe not. This assumes you're using lined tunnels. Hard rock mining (and hard rock TBMs for that matter, if you go that route) don't require a structural lining.

But you also need to import massive TBM. Change the imported mass from TBM to more mining equipment and your steel becomes cheaper.

Unless you're envisioning above-ground structures made entirely by hand (yikes, labor costs!), you're going to need to add "import massive above-ground construction equipment" to the other column.

Again, hard to tell which is heavier when you run the full apples-to-apples comparison. At the very least you need to normalize for how many m3/year of habitable space each set of equipment can produce. Perhaps you need 3-4 sets of above-ground construction equipment to match a single TBM. Personally I don't know how those numbers will shake out, but you seem pretty sure! ;)


But dont actually need any concrete. There are better ways to make cheap tensile material on Mars than using steel though.

Yes, you don't need concrete. :) And surely these "cheap tensile materials" can be used in tunneling too, so that's not really an advantage either way.

If you have the ability to built underground, you have the ability to build on the surface. Not necessarily the other way round though.

I disagree, but I also fail to see the relevance.

I think this all depends on what imaginary hypothetical set of equipment you're assuming in both cases. Surely you can cherry-pick equipment that will satisfy both cases, but that doesn't mean A) either option is "best" (nice vague word there to kick off this discussion :D), or B) that you can't cherry-pick a third option where you can build underground but not on the surface.

Surely I can just as well imagine a hypothetical where SpaceX brings a self-pourpoising TBM w support equipment and little else, therefore having the ability to build underground but not the ability to build on the surface. That doesn't mean that SpaceX will adopt my plan, or that it's somehow "best." It's just a cherry-picked example. I submit that the exact same logic applies to whatever two cherry-picked scenarios you're picturing above.

Comparing to literally the most deadly product in the world isn't great. That's like saying, "don't worry, your risk of death is lower than a typical base-jumper on Earth!"
Being alive gives you a 20% chance of dying of cancer. Being a smoker increases that by 4%, being on Mars about 2-3%. Living under 4m of water will bring it to earth levels again. Infact, if your [sic] shielded for 18 hours a day, you can spend the rest of the day outside with no noticeable increase of Cancer at all. Base jumpers on the other hand have a 1.7% chance of dying per year of activity. Id rather be on Mars.

Yeah I follow the math, I'm just pointing out the rather strange value system you seem to be employing. Killing more people than Earth's deadliest product is fine, but LED skylights, that's where you draw the line. ???

Do the math on that proposal. I think you'll find that the per-person volume needed for radiation shielding vastly out-paces the per-person volume needed for fish farming. So most of your water roof will be purpose-built, and if you're dedicating water solely for that purpose it's going to be expensive.

Ditto for re-using the pool as cooling water. The great thing about using eg a river for cooling water is that it flows away. In your proposal the heat would just build up in the pool, getting hotter and hotter until it boils. Sure you'll reject some heat off the roof surface, but you could accomplish the exact same performance with just a simple flat-plate radiator. So the synergy of combining radiation shielding and cooling pond isn't really providing much "for free."
Your [sic] actually right on the first part! You can feed about 30% of all your calorie intake with just fish farms.

Just fish farms? I'm afraid to ask: what do the fish eat?

The water on the roof is for radiation proofing, but doubles for other things too. Including recreational water skiing or what ever. The water would need to be covered to stop sublimation (also why you can go ski on it).

The pressure needed just to stop sublimation is a lot lower. If you want to be able to water ski on it, essentially the entire cost of that upper air containment structure would need to be economically justified solely for the purpose of water skiing.

The reason why you use water is because its excellent at carrying heat, and easy to move about.It iss just a place with a large surface area to dump heat. Obviously this will need to be controlled. But your [sic] still radiating a few 100w/m2 by doing this.

Sure, I get that. It's just that you can accomplish the exact same thing with pipe and a flat plate radiator. You're not getting much "for free" just from this synergy, because effectively your pool's heat rejection function is only replacing a much smaller and simpler system.

With LEDs, lighting isn't a big power drain.

As for children's eye development, clearly being around typical lighting for most of the time is fine. Providing a brightly-lit play area is trivial.
This is underrated.
Research suggest that children that dont get daily exposure to about 15 000 lux start to suffer a host of issues ranging from eye development to MS to cognitive issues. The average well lit office (higher than a regular home) is about 500 lux.
If you have a window in a room, chances are your [sic] getting well over 10 000 lux during the day. Step outside on a cloudy day, you have about 40 000 lux. Mars has no clouds, so your typical surface has about 60 000 Lux, or about 45000 lux under 5m of water.

What's wrong with my proposed solution again? Just make sure your "brightly lit play area" is sufficiently bright.

If you're growing plants you need such areas anyway, and contact with plants is good for child development. So perhaps some of the kid play spaces could be combined with plant growing spaces. If not, providing dedicated play areas isn't a big expense.

Overall, there are lots of issues that will need to be solved when people go to Mars. Solving the problem technically will however be pointless if you don't solve it for humans. Very few people are made out to be miners and submariners.

Turns out "humans" are quite a diverse bunch, so "solve it for humans" isn't a well-defined point.

Would you consider Mars "pointless" if only 50% of people are bad-ass enough to go? 90%? 99%? All of humanity except one person? Just trying to figure out where the "wimpiness cutoff" lies regarding this particular statement. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: JaimeZX on 10/06/2020 10:49 pm
Just fish farms? I'm afraid to ask: what do the fish eat?
Soylent Fish is PEOPLE! It's PEEEEEEEEEEEEPLLLLLLLLLLLLLLLLLEEEEEEEEE  (https://offtopic.com/styles/default/xenforo/smilies/ot/laugh.gif)

This is underrated. Research suggest that children that dont get daily exposure to about 15 000 lux start to suffer a host of issues ranging from eye development to MS to cognitive issues. The average well lit office (higher than a regular home) is about 500 lux.
If you have a window in a room, chances are your [sic] getting well over 10 000 lux during the day. Step outside on a cloudy day, you have about 40 000 lux. Mars has no clouds, so your typical surface has about 60 000 Lux, or about 45000 lux under 5m of water.
This brings up a quite interesting point... the nutritional supplies of our colonists. Presumably they will need to be importing massive quantities of Vitamin D until we come up with a synthetic source there... and Omega 3s (EPA/DHA), unless the notional fish farm mentioned above is heavily biased towards fatty salmon / mackerel / etc.
Early studies show low maternal levels of both may be associated with autism in offspring, so that'd be quite a good thing to figure out before we send "mating pairs." (Plenty of other examples of critical nutrients. May be relevant to a new thread, I dunno.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/06/2020 11:06 pm
This brings up a quite interesting point... the nutritional supplies of our colonists. Presumably they will need to be importing massive quantities of Vitamin D until we come up with a synthetic source there... and Omega 3s (EPA/DHA), unless the notional fish farm mentioned above is heavily biased towards fatty salmon / mackerel / etc.
Early studies show low maternal levels of both may be associated with autism in offspring, so that'd be quite a good thing to figure out before we send "mating pairs." (Plenty of other examples of critical nutrients. May be relevant to a new thread, I dunno.)

For vitamin D, the synthetic source could be tanning lamps. :) Or alternately, Wiki tells us...

Quote from: Wikipedia
Vitamin D3 (cholecalciferol) is produced industrially by exposing 7-dehydrocholesterol to UVB light, followed by purification.[180] The 7-dehydrocholesterol is a natural substance in fish organs, especially the liver,[181] or in wool grease (lanolin) from sheep. Vitamin D2 (ergocalciferol) is produced in a similar way using ergosterol from yeast or mushrooms as a starting material.

Fish (and all other animals) are incapable of synthesizing their own omega 3 fatty acids. Only plants can do that. So to make it you'll need to bring at least one of: phytoplankton, walnuts, flax, hemp, etc.
Title: Re: Envisioning Amazing Martian Habitats
Post by: JaimeZX on 10/06/2020 11:49 pm
For vitamin D, the synthetic source could be tanning lamps. :)
I want to avoid hijacking this thread, but I suspect if Mars colonists are already concerned about elevated cancer risk, they're not going to be keen on another potential source. Since the synthesizing process is well understood, it may be straightforward to bring D3 production to Mars, but when that makes economic sense vs. sending over a bunch of supplements on each ship remains to be seen. Ditto for other micronutrients.  Again, without going too far off-topic, the farm soils they use are likely to either be nutrient-depleted from the get-go, or rapidly become so.  More research / analysis required in this area, I think.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/07/2020 12:27 am
For vitamin D, the synthetic source could be tanning lamps. :)
I want to avoid hijacking this thread, but I suspect if Mars colonists are already concerned about elevated cancer risk, they're not going to be keen on another potential source.

I was aware of the irony. That's why I immediately (in the very next sentence!) offered non-carcinogenic alternatives. :)

Since the synthesizing process is well understood, it may be straightforward to bring D3 production to Mars, but when that makes economic sense vs. sending over a bunch of supplements on each ship remains to be seen. Ditto for other micronutrients.  Again, without going too far off-topic, the farm soils they use are likely to either be nutrient-depleted from the get-go, or rapidly become so.  More research / analysis required in this area, I think.

If you're worried about depleting nutrients, I would recommend this eye-opening video from microbiologist Elaine Ingham. She explains how living soil isn't just some inert "sponge" to store fertilizer, it's actually a factory that chemically breaks down rock into those various micro-nutrients. Contained within ordinary rock/sand/clay is literally thousands of years of nutrients, just waiting to be solubilized by microbes and slurped up by plants.

https://www.youtube.com/watch?v=x2H60ritjag

We'll definitely need to provide concentrated streams of CO2, water, and nitrogen (together these elements make up >75% of all biomass), but beyond that we could in theory rely largely on soil microbiology to do most of the "fertilizer manufacturing," with only minor augmentation (or simple batch blending) when soil tests indicate a particular batch of regolith is deficient in some essential element or two (P, K, Mg, B, whatever).
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/07/2020 02:48 am
if building underground saves on per-volume costs then underground living could still be cheaper overall.

Starships could easily deliver 100,000 m3 of completed and protected (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129055#msg2129055) surface hab with less cargo mass than one TBM system (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129248#msg2129248).

Cheaper space is plausible in glacier ice, 1 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615) 2 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127519#msg2127519) 3 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2128635#msg2128635), not in rock.  That's why ice numbers were detailed 20 years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615).

First numbers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/07/2020 03:18 am
Yeah I follow the math, I'm just pointing out the rather strange value system you seem to be employing. Killing more people than Earth's deadliest product is fine, but LED skylights, that's where you draw the line. ???
Just want to mention this one thing, because this is going all over the place. But I still say its under rated.

Lighting

You need about 150W/m2 to get enough lighting for healthy childhood development and some plant growth. (lowest hopeful levels)
I presume no one is hoping to plant food underground? as You will be using 15Kw per person just lighting the crop. Or 1 transportable nuclear power plant per 130 people.



Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/07/2020 03:26 am
if building underground saves on per-volume costs then underground living could still be cheaper overall.

Starships could easily deliver 100,000 m3 of completed and protected (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129055#msg2129055) surface hab with less cargo mass than one TBM system (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129248#msg2129248).

How many times do I have to say it? TBMs aren't the only way to make tunnels.

Cheaper space is plausible in glacier ice, 1 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615) 2 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127519#msg2127519) 3 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2128635#msg2128635), not in rock.  That's why ice numbers were detailed 20 years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615).

[deleted]

Do you honestly expect everyone to crawl through these huge hyperlink trees in their entirety? I'm certainly not going to. Past experience has taught me that those linked posts (always links to LMT's own posts, never anyone else's) are tangentially related at best, and totally irrelevant at worst. If you want to say something, just say it. [deleted]

First numbers.

First, plausible assumptions. Just saying "numbers" isn't very helpful. [deleted]
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/07/2020 05:30 am
Come to Mars. Live in a tunnel, just with 1/3 gravity.

That's gonna bring in loads of (paying) colonists.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Nevyn72 on 10/07/2020 06:50 am
Come to Mars. Live in a tunnel, just with 1/3 gravity.

That's gonna bring in loads of (paying) colonists.

Unless the tunnels are really quite big there's going to be a LOT of bruised heads around the place.......  :-\
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/07/2020 07:23 am
Come to Mars. Live in a tunnel, just with 1/3 gravity.

That's gonna bring in loads of (paying) colonists.

Unless the tunnels are really quite big there's going to be a LOT of bruised heads around the place.......  :-\

Only if people actively jump; walking height is unaffected but the maximum running height in Martian gravity actually goes down, based on both weight compensation (suspension) and parabolic flight studies.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 10/07/2020 08:51 am
I dare to say that air pressure alone may be a sufficient justification for underground construction (not the same as tunneling with a TBM). Mars is essentially vacuum as far as habitation is concerned. Martian habitat will be more like a space station rather than a building. Thus I believe there will be only two viable ways to make lots of pressurized living space on Mars - either you import a prefabricated pressure vessel and cover it with a few meters of soil, or you dig deep underground and then treat the walls with some kind of an airtight liner or sintering. Likely first method will be used initially, second method later on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/07/2020 12:29 pm
I dare to say that air pressure alone may be a sufficient justification for underground construction (not the same as tunneling with a TBM). Mars is essentially vacuum as far as habitation is concerned. Martian habitat will be more like a space station rather than a building. Thus I believe there will be only two viable ways to make lots of pressurized living space on Mars - either you import a prefabricated module and cover it with a few meters of soil, or you dig deep underground and then treat the walls with some kind of an airtight liner or sintering. Likely first method will be used initially, second method later on.

If you can sinter rock to make an airtight lining, you can sinter regolith on the surface to make an airtight lining.
Title: Re: Envisioning Amazing Martian Habitats
Post by: blasphemer on 10/07/2020 12:34 pm
If you can sinter rock to make an airtight lining, you can sinter regolith on the surface to make an airtight lining.

I doubt that as it would just explode outwards when pressurized. You need lots of heavy soil to provide that counterpressure, even more than required for radiation protection due to low Martian gravity. At that point you may as well dig underground, IMHO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/07/2020 12:42 pm
If you can sinter rock to make an airtight lining, you can sinter regolith on the surface to make an airtight lining.

I doubt that as it would just explode outwards when pressurized. You need lots of heavy soil to provide that counterpressure, even more than required for radiation protection due to low Martian gravity. At that point you may as well dig underground, IMHO.

You design the walls so that they are concave, not convex. This is the approach that SEArch+ took in the 3D Mars habitat competition. The walls are in compression, not tension, and you can make things much stronger that way with basic building materials. If you are designing for a city with up to a million people, obviously you will have more sophisticated materials and construction techniques. MaNaeSWolf also made use of compressive surfaces (arches) in the Nexus Aurora entry to the Mars Society competition. However, just making the pressure vessels out of steel and just importing the sheeting would be a small part of the mass budget.

But if you really want strength and low tech, just freeze Martian mud. At Mars ambient temperatures, it's equivalent to basalt.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/07/2020 01:28 pm
if you really want strength and low tech, just freeze Martian mud. At Mars ambient temperatures, it's equivalent to basalt.

A mudrock is strong (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380), but the sheet falls apart in creation, as it dries and shrinks.

Would you build an air tank from mudrock chips?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/07/2020 07:09 pm
if you really want strength and low tech, just freeze Martian mud. At Mars ambient temperatures, it's equivalent to basalt.

A mudrock is strong (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380), but the sheet falls apart in creation, as it dries and shrinks.

Would you build an air tank from mudrock chips?

Frozen Martian mud is not mudrock. Please read what I have written.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/07/2020 08:29 pm
if you really want strength and low tech, just freeze Martian mud. At Mars ambient temperatures, it's equivalent to basalt.

A mudrock is strong (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380), but the sheet falls apart in creation, as it dries and shrinks.

Would you build an air tank from mudrock chips?

Frozen Martian mud is not mudrock. Please read what I have written.

Absent bags, it certainly is.  And it's certainly not basalt, below.  Keep thread info in mind.

Refs.

Zacny, K.A. and Cooper, G.A., 2007. Coring basalt under Mars low pressure conditions. IJMSE, 3, pp.1-11.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 10/07/2020 10:05 pm
Some interesting ideas here. But one thing I would add is that we do not yet have a clear understanding of how best to build on Mars or any detail concerning the nature of the subsurface or how insitu materials might best be utilized. I doubt very much that any significant building will be undertaken until at least one human crew has visited and carried out a lot of experimentation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/07/2020 10:07 pm
Starships could easily deliver 100,000 m3 of completed and protected (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129055#msg2129055) surface hab with less cargo mass than one TBM system (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129248#msg2129248).

Cheaper space is plausible in glacier ice, 1 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615) 2 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127519#msg2127519) 3 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2128635#msg2128635), not in rock.  That's why ice numbers were detailed 20 years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615).

Past experience has taught me that those linked posts... are tangentially related at best, and totally irrelevant at worst.

That material's relevant, so your story falls apart at the first example.

--

Better refs would be interesting, especially wrt robotics suitable for autonomous ice-melt excavation.  Conceivably all-electric melt-bots could be far more versatile than the balloon-melt system of Powell et al. 2000 (http://www.niac.usra.edu/files/studies/final_report/424Powell.pdf).  Autonomous electric vaporization of thousands of cubic meters daily (https://forum.nasaspaceflight.com/index.php?topic=44508.msg1933999#msg1933999) could be a significant capability, and not obviously a greater challenge than surface operations.

Image:  Vulcanic 3 MW immersion heater.

https://www.youtube.com/watch?v=njW7mBH0ORQ
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/08/2020 06:41 am
Talking about material.

Once you have methane production up, you have invested 80% of the energy to create a lot of different polymers.
We designed a structure made out of a polymer (cant remember exactly which one) with combined steel and basalt fibers with a pressurised surface area of 150 000m2.
Yeah, keeping 3 Atm of pressure (1 + 2 for safety) is not that hard. The hoop stresses are easily overcome with a little more thickness. Humans have been building tanks for a long time.
The total energy investment for this structures material is less than what it talks to re-fuel 2 starships.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/08/2020 07:22 am
if you really want strength and low tech, just freeze Martian mud. At Mars ambient temperatures, it's equivalent to basalt.

A mudrock is strong (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127380#msg2127380), but the sheet falls apart in creation, as it dries and shrinks.

Would you build an air tank from mudrock chips?

Frozen Martian mud is not mudrock. Please read what I have written.

Absent bags, it certainly is.  And it's certainly not basalt, below.  Keep thread info in mind.

Refs.

Zacny, K.A. and Cooper, G.A., 2007. Coring basalt under Mars low pressure conditions. IJMSE, 3, pp.1-11.

So this paper has 300MPa UCS basalt - samples likely deliberately chosen for their high strength in an engineering test.

Thanks for the references. 
How about we dig tunnels, for ice, perhaps,  then use the tunnels to installs habs.  On the surface, we use the rock extracted from the mine to cover more habitats?  A mix of both solutions?
Seems energy/ressources efficient.


My pleasure.

Here are some more references. In the first, they examine water well extraction (drilling, melting the ice and extracting it). For some reason not specified, they essentially abandon the idea of mining solid ice blocks.

https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf

In another paper, it is noted that ice blocks are too strong to remove at with a backhoe at Martian temperatures. In fact, the strength of ice on Mars is equivalent to that of basalt (!). A roadheader would struggle with it. So for large quantities of Martian ice, they need to be drilled and blasted out. The author notes that explosives are a Bad Idea on Mars due to the low gravity making the debris fly much, much further. You only want to do this if you are ice mining for a colony.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

So basically, ice on Mars is as strong as rock.

Another paper indicates that permafrost at 20-30% ice is quite hard but still possible to excavate, especially if cut with a saw to 10cm first. Below 15% the permafrost is not cohesive and can be excavated with a backhoe.

https://arc.aiaa.org/doi/abs/10.2514/6.2016-0227

From this very thread.

The figure below is what I base my "ice mud is as strong as basalt" throwaway line on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/08/2020 09:11 am
You dont need super high performing tensile materials if your piling it on thick.

You need 2.5Mpa to hold 5Atm of air, if you have a 10m radius structure with 1m thick walls.

Take the 200mm thick concrete panels you need to keep your tunnels from collapsing, and just assemble them on the surface for a much quicker habitat. No fancy material needed, and you don't need to ship in massive TBM's.

What's cool about this, is that a structure like this would collapse without internal pressure. You can literally built bigger structures with less material on Mars because of internal pressures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/08/2020 10:46 am
If I am in a habitat on Mars that is losing pressure because of a malfunction, I would much prefer not to have to worry about a cave-in as well. I think it makes sense to require from Mars habitats that they remain structurally sound, even without internal pressure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/08/2020 11:02 am
If I am in a habitat on Mars that is losing pressure because of a malfunction, I would much prefer not to have to worry about a cave-in as well. I think it makes sense to require from Mars habitats that they remain structurally sound, even without internal pressure.
Yes, that should be a given. Just because you can make structures that only work with internal pressure, does not exclude a few columns from being built.

You need to build the initial structure without any internal pressure anyway, so self supporting makes sense from a practical construction point of view.

Just saying, its possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: guckyfan on 10/08/2020 01:13 pm
If I am in a habitat on Mars that is losing pressure because of a malfunction, I would much prefer not to have to worry about a cave-in as well. I think it makes sense to require from Mars habitats that they remain structurally sound, even without internal pressure.
Yes, that should be a given. Just because you can make structures that only work with internal pressure, does not exclude a few columns from being built.

You need to build the initial structure without any internal pressure anyway, so self supporting makes sense from a practical construction point of view.

Just saying, its possible.

I have made that argument for a long time. IMO any structure needs to be sound pressurized and unpressurized. Being sound only pressurized can have an advantage though, if you add radiation shielding mass on top after it is pressurized.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/08/2020 04:34 pm
So this paper has 300MPa UCS basalt - samples likely deliberately chosen for their high strength in an engineering test.

::)  His sample had "no record of its physical properties" at purchase.  Don't ignore text contradicting an assumption, Lampyridae.

The figure below is what I base my "ice mud is as strong as basalt" throwaway line on.

Your immature mudrock fractures as it dries, each chip's UCS dropping with desiccation.  Plus your JSC-1a is cinder, simulating unprocessed lunar regolith, not processed martian grains.  That's why JSC-1a grains are huge, up to 1 mm (https://www.nasa.gov/sites/default/files/atoms/files/03_jsc-1a_lunar_regsimulant_update_bgustafson.pdf).  They give "ice mud" chips more fragile than clay in a desiccating environment.

This happens to have been my line of work for several years, so readers can assume I know some basics about rocks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/08/2020 04:38 pm
We designed a structure made out of a polymer (cant remember exactly which one) with combined steel and basalt fibers with a pressurised surface area of 150 000m2.
Yeah, keeping 3 Atm of pressure (1 + 2 for safety) is not that hard. The hoop stresses are easily overcome with a little more thickness.

A pressure vessel 220 m in diameter?  That would be something to see.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/08/2020 06:27 pm
A pressure vessel 220 m in diameter?  That would be something to see.
Not a cylinder. But a series of cylinders at 15m diam that are fused together. The floor area was 150 000m2. Imagine an air mattress. Designed to be used as a farm.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/08/2020 09:44 pm
A pressure vessel 220 m in diameter?  That would be something to see.
Not a cylinder. But a series of cylinders at 15m diam that are fused together. The floor area was 150 000m2. Imagine an air mattress. Designed to be used as a farm.
Yes, using tensile columns in the pressure dome reduces the strain tremendously.  Not very good for football games but excellent for all other applications.  There are a few examples a few hundred pages back.  Or thereabouts :-), we've cycled though this at least once, perhaps twice.

I also expect that whoever writes the Martian building code will require that structures remain stable and safe at least until they can be safely evacuated as a basic design feature.  This will be true for both surface and underground structures.  If after losing pressure in a controlled way a tunnel or a structure collapses, if there is a certainty that everybody has been able to leave, then it's more an insurance problem that a design problem.  The insurer might not want the building/tunnel to collapse. 
And one would expect that there would be complementary provisions insuring that the collapse, or at least the loss of pressure of an habitat/module would not affect linked modules.
Modern building are compartmentalized in a number of ways, the same should be true for Mars. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/09/2020 11:26 am
Here is a quick dirty section of what some of these structures could be like.
This is for the million person City State competition that we are presenting at next week.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/09/2020 02:08 pm
I'll be presenting as well for the 1 000 000 person City State; seems I have the best English ;).  We have similar solutions, but without the water shield, just more compressed regolith and a different take on public vs private spaces.  Plus the lower part of our cylinders are buried more deeply.   Last year I was all for tunnels, this year, mostly surface.  I think the reality, if it ever comes to be, will be a bit like concrete structures vs steel structures, sometimes one, sometimes the other.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Frogstar_Robot on 10/09/2020 02:27 pm
For those not presenting, this is the competition ? https://www.marssociety.org/news/2020/09/28/finalists-chosen-in-mars-city-state-design-competition/

I wish everyone good luck with their presentations!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/09/2020 04:11 pm
Starships could easily deliver 100,000 m3 of completed and protected (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129055#msg2129055) surface hab with less cargo mass than one TBM system (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129248#msg2129248).

Cheaper space is plausible in glacier ice, 1 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615) 2 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127519#msg2127519) 3 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2128635#msg2128635), not in rock.  That's why ice numbers were detailed 20 years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615).

Past experience has taught me that those linked posts... are tangentially related at best, and totally irrelevant at worst.

That material's relevant

Your assertion, let's recall, was that ice is easier than rock. But your links provide nothing about rock (ignoring the non-sequitur about designed-for-Earth TBM mass, already addressed). Tangentially related sure, but they don't prove what you're trying to use them to prove.

If you want to compare two things, you need to look at... two things. Not one (and no, "one plus a strawman of the other" eg your largest-TBM-in-the-world doesn't count).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/09/2020 04:23 pm
So this paper has 300MPa UCS basalt - samples likely deliberately chosen for their high strength in an engineering test.

::)  His sample had "no record of its physical properties" at purchase.  Don't ignore text contradicting an assumption, Lampyridae.

Careful LMT, there's not necessarily a contradiction here. The quoted text doesn't exclude the possibility that the author cherry-picked it as the strongest from among another 10 samples he had lying around which also had "no record."

The point is that it's a statistical outlier for basalt's strength. No matter how it happened, it effects the validity of the comparison.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/10/2020 10:25 pm
Starships could easily deliver 100,000 m3 of completed and protected (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129055#msg2129055) surface hab with less cargo mass than one TBM system (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2129248#msg2129248).

Cheaper space is plausible in glacier ice, 1 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615) 2 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2127519#msg2127519) 3 (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2128635#msg2128635), not in rock.  That's why ice numbers were detailed 20 years ago (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2124615#msg2124615).

Past experience has taught me that those linked posts... are tangentially related at best, and totally irrelevant at worst.

That material's relevant

Your assertion, let's recall, was that ice is easier than rock. But your links provide nothing about rock (ignoring the non-sequitur about designed-for-Earth TBM mass, already addressed). Tangentially related sure, but they don't prove what you're trying to use them to prove.

If you want to compare two things, you need to look at... two things. Not one (and no, "one plus a strawman of the other" eg your largest-TBM-in-the-world doesn't count).

You agree that TBM numbers are awful, relative to ice-melt excavation.  No engineer would disagree.

But there are many ways to tunnel.

How else to tunnel through -60 C, 300 MPa UCS basalt? 

--

The quoted text doesn't exclude the possibility that the author cherry-picked [that basalt sample] as the strongest from among another 10 samples he had lying around which also had "no record."

It's "from a local stone dealer":  a Chinese sample, just lying around.  ::)

Judging from your guesses, you and Lampyridae didn't read the paper.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/11/2020 12:35 am
You agree that TBM numbers are awful, relative to ice-melt excavation.  No engineer would disagree.

I agree that your TBM numbers are awful, because you baseline was literally the heaviest TBM on Earth. This is an unreasonable starting assumption.

But there are many ways to tunnel.

How else to tunnel through -60 C, 300 MPa UCS basalt?

Come now, I know you're reading the same thread as everyone else. Does the word "roadheader" rings any bells?

And again, 300 MPa isn't necessarily a good assumption for basalt strength.

The quoted text doesn't exclude the possibility that the author cherry-picked [that basalt sample] as the strongest from among another 10 samples he had lying around which also had "no record."

It's "from a local stone dealer":  a Chinese sample, just lying around.  ::)

So? That doesn't contradict anything I said. You can certainly cherry-pick samples and end up with a Chinese sample from a local stone dealer. Fortunately whether or not the experimenter actually cherry-picked their samples (which personally I doubt) is irrelevant to my point (see below).

Judging from your guesses, you and Lampyridae didn't read the paper.

Didn't read it, don't need to. If it's a strength outlier (as Lampyridae claims), that contaminates the results regardless of whether or not the experimenter engaged in sample hanky panky. If it's not a strength outlier, then it doesn't. Simple as that.

It also helps people to read your citations if you include a hyperlink. For someone who enjoys linking to his own writing so much you'd think it'd be second nature. :) Here you go: http://www.marsjournal.org/contents/2007/0001/files/zacny_mars_2007_0001.pdf
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/11/2020 01:48 am
You agree that TBM numbers are awful, relative to ice-melt excavation.  No engineer would disagree.

I agree that your TBM numbers are awful, because you baseline was literally the heaviest TBM on Earth. This is an unreasonable starting assumption.

But there are many ways to tunnel.

How else to tunnel through -60 C, 300 MPa UCS basalt?

Come now, I know you're reading the same thread as everyone else. Does the word "roadheader" rings any bells?

And again, 300 MPa isn't necessarily a good assumption for basalt strength.

The quoted text doesn't exclude the possibility that the author cherry-picked [that basalt sample] as the strongest from among another 10 samples he had lying around which also had "no record."

It's "from a local stone dealer":  a Chinese sample, just lying around.  ::)

So? That doesn't contradict anything I said. You can certainly cherry-pick samples and end up with a Chinese sample from a local stone dealer. Fortunately whether or not the experimenter actually cherry-picked their samples (which personally I doubt) is irrelevant to my point (see below).

Judging from your guesses, you and Lampyridae didn't read the paper.

Didn't read it, don't need to. If it's a strength outlier (as Lampyridae claims), that contaminates the results regardless of whether or not the experimenter engaged in sample hanky panky. If it's not a strength outlier, then it doesn't. Simple as that.

It also helps people to read your citations if you include a hyperlink. For someone who enjoys linking to his own writing so much you'd think it'd be second nature. :) Here you go: http://www.marsjournal.org/contents/2007/0001/files/zacny_mars_2007_0001.pdf

Your "Didn't read it, don't need to," stance says a lot, Twark_Main.

And posters know that roadheaders can't hack basalt (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1607290#msg1607290).  But you don't need to read that, either.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/11/2020 07:02 pm
Your "Didn't read it, don't need to," stance says a lot, Twark_Main.

Is any of it on-topic? ::)

And posters know that roadheaders can't hack basalt (https://forum.nasaspaceflight.com/index.php?topic=41427.msg1607290#msg1607290).  But you don't need to read that, either.

Another link that doesn't say what you claim. 143 MPa is quoted as the max UCS of basalt in the Deccan traps, not the rock strength limitation of roadheaders.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/12/2020 01:35 am
Laser Cryobot Tech for Hab Excavation

Laser-powered cryobot tech has potential to overcome issues of in-glacier power delivery range and sediment accumulation.  E.g., the VALKYRIE demonstrator of Stone et al. 2014, which descends on fiber-optic cable and melts ice with a metal beam dump.  Images below. 

Alternately, a 10.6 micron CO2 laser can melt ice directly, as in Sakurai et al. 2016.  This method might give the most mass-efficient excavation system, provided meltwater is removed by a separate mass-efficient device.  E.g., visible light might be pumped down the same fiber optic cable and converted to PV electricity within the excavator, to power both the excavator and also a small induction + radiator heating loop that boils off meltwater.

Refs.

Sakurai, T., Chosrowjan, H., Somekawa, T., Fujita, M., Motoyama, H., Watanabe, O. and Izawa, Y., 2016. Studies of melting ice using CO2 laser for ice drilling. (https://www.sciencedirect.com/science/article/abs/pii/S0165232X15002116) Cold Regions Science and Technology, 121, pp.11-15.

Stone, W.C., Hogan, B., Siegel, V., Lelievre, S. and Flesher, C., 2014. Progress towards an optically powered cryobot (https://www.cambridge.org/core/journals/annals-of-glaciology/article/progress-towards-an-optically-powered-cryobot/33B377D112246F4F0EE48CC8EEA8EAB0/core-reader). Annals of Glaciology, 55(65), pp.2-13.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 10/13/2020 09:22 am
But if you really want strength and low tech, just freeze Martian mud. At Mars ambient temperatures, it's equivalent to basalt.

Just to remind folks what started this. My paraphrasing of a table.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

Apparently, despite having worked in the field for many years, I do not know what the typical UCS range of basalt is.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 10/13/2020 04:43 pm
But if you really want strength and low tech, just freeze Martian mud. At Mars ambient temperatures, it's equivalent to basalt.

Just to remind folks what started this. My paraphrasing of a table.

http://rascal.nianet.org/wp-content/uploads/2016/08/Mobile-In-Situ-Water-Extractor-MISWE-for-Mars-Moon-and-Asteroids-In-Situ-Resource-Utilization.pdf

Apparently, despite having worked in the field for many years, I do not know what the typical UCS range of basalt is.

No, you misread one simple table (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2140476#msg2140476); "ice mud" UCS isn't close at any temperature, and you forgot sublimation (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2140604#msg2140604).  Also, the table doesn't give massive basalt UCS or its temperature relation.  Even at room temperature, massive basalt UCS ranges up to 300 MPa:  Zacny and Cooper (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2140291#msg2140291) knew the relevance.

Say more about your mud-hab idea (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2140128#msg2140128).
Title: Re: Envisioning Amazing Martian Habitats
Post by: jpo234 on 10/18/2020 08:58 am
From https://www.reddit.com/r/NexusAurora/comments/jd9ip5/nexus_aurora_wins_the_mars_colony_design_contest/

Quote
Nexus Aurora WINS the Mars Colony Design Contest! Robert Zubrin just announced our international team of Nexus Aurora has won the competition! (and $10k) Out of 176 excellent teams participating, we are very proud to have won! Read our full report here: [https://nexusaurora.com/report.pdf](https://nexusaurora.com/report.pdf) - Want to join our team and help humanity become a multiplanetary species? Shoot us a message here on Reddit and join our Discord Server. We only just begun! Edit: here are the top five awards, handed out by Zubrin himself at the 2h15m mark: https://youtu.be/BMmMM5CF9yc


Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/18/2020 11:39 am
Came in third.
It was very close, could have gone either way, but the winner was a very strong team.  And was set up as an organization with ongoing projects, not just a one shot team. So good for them and I hope they do keep on.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 10/18/2020 06:27 pm
Big congrats to the winning team and to you, lamontagne, for the bronze medal for your team! With so many teams competing, both results are very impressive indeed. You have entered Mars colonisation history!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 10/18/2020 06:57 pm
So happy with my team for coming in Second! Now we've been tried and tested for two years in a row, we're going to start branching out into other projects and incorporate as a proper R&D company in Australia.
Nexus Aurora definietly deserved first! And Congrats to Lamontagne for coming in Third, your presentation was fantastic!

Also: All top 3 hang out in this thread!
Nasaspaceflight representing!
Title: Re: Envisioning Amazing Martian Habitats
Post by: leovinus on 10/18/2020 08:19 pm
Very cool, congrats to all teams. While I would love to read more and see a link to the final presentation/report of the winning team above, I could not find a pdf of the other team presentations. Are they online?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Rocket Surgeon on 10/18/2020 08:38 pm
Very cool, congrats to all teams. While I would love to read more and see a link to the final presentation/report of the winning team above, I could not find a pdf of the other team presentations. Are they online?

They'll be published in a book from the Mars Society in the next few months

Presentations of the top 10 will probably be on youtube within a couple of weeks
Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/19/2020 02:43 pm
Well done to everyone.

Was great to see so many people entering. I hope it grows next year.
Im sad I did not get to see all of the presentations as we had to practice before hand.

Any guesses to what next years competition may be?
Title: Re: Envisioning Amazing Martian Habitats
Post by: KBK on 10/26/2020 05:22 pm
This just in...:

NASA confirms there is evidence of hidden water on sunlit surface of the moon (https://twitter.com/i/events/1320767402410307585)

Quote
On Monday, researchers from NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) confirmed for the first time that molecular water has been discovered on the sunlit surface of the moon, indicating “water may be distributed across the lunar surface, and not limited to cold, shadowed places.” Researchers also said that the discovery will benefit future exploration plans.

Which bodes well for the ideas of finding water on Mars, more than currently expected...in places not yet considered to be plausible and whatnot.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/30/2020 01:15 am
The Southern Martian settlement of our City State: Surya, City of the Sun.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 10/30/2020 10:54 am
The Southern Martian settlement of our City State: Surya, City of the Sun.

Nice render as always.

I would expect the buildings/structures to be laid out in a more consistent way, optimised to the angle of the sun's movement across the sky, particularly the winter path. Ie, light-gaps optimised north for a low winter sun in the southern hemisphere, south in the northern.

I would also expect the ground between the structures to be completely landscaped in any area built-up like this. Possibly paved or sintered to cut down on dust, but certainly landscaped after being chewed up during construction.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/30/2020 01:08 pm
The Southern Martian settlement of our City State: Surya, City of the Sun.

Nice render as always.

I would expect the buildings/structures to be laid out in a more consistent way, optimised to the angle of the sun's movement across the sky, particularly the winter path. Ie, light-gaps optimised north for a low winter sun in the southern hemisphere, south in the northern.

I would also expect the ground between the structures to be completely landscaped in any area built-up like this. Possibly paved or sintered to cut down on dust, but certainly landscaped after being chewed up during construction.
The lack of consistency is supposed to reflect the effect of uneven ground at the Nicholson crater.  However, I still haven't figured out how to import Martian terrain, so it's inconsistent in a consistent way, and I think I may have been overly decorative in my arrangement  :-)
You're right about the terrain.  Again, it's mostly because I added random bumps as the original flat terrain was 'too' flat.  The city 'in my head' is build on more or less 5 degree slope on the Southern side of Nicholson's central peak.  I added a few random roads to give an effect of 'external' operations, but obviously the effect is insufficient.

During the preparation of the project, we wondered if the large blank walls of regolith might be decorated with large pictures/photographs on Mars, giving something to look at out of those large windows :-)  Very large printed colored images of forests, or abstract work, could be rolled out fairly cheaply. As these would probably be north facing they probably wouldn't be covered with solar cells, another alternative we envisioned.
Another alternative would be to cover them with sculptures.  We actually touch on that briefly in our report.
The city shown houses about 100K people.  And it's at the limit of my computer to model  :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 10/30/2020 09:29 pm
Great render lamontagne! Tons of little details.

The Southern Martian settlement of our City State: Surya, City of the Sun.

Nice render as always.

I would expect the buildings/structures to be laid out in a more consistent way, optimised to the angle of the sun's movement across the sky, particularly the winter path. Ie, light-gaps optimised north for a low winter sun in the southern hemisphere, south in the northern.

[snip]
The lack of consistency is supposed to reflect the effect of uneven ground at the Nicholson crater.  However, I still haven't figured out how to import Martian terrain, so it's inconsistent in a consistent way, and I think I may have been overly decorative in my arrangement  :-)

I think Paul451 is suggesting they'd all be oriented in the same direction not due to terrain considerations, but because the buildings looks like they employ passive solar design (IMO a Very Good Idea on such a cold planet), so one would expect the building's long axis to be oriented east-west with the majority of glazing on the south side (because the Sun moves across the southern half of the sky).

In passive solar it's generally advised to oversize east glazing and undersize west glazing, resulting in a "smoothed out" daily temperature graph. Morning is coldest so you want warming east Sun, but by evening you're already in the hottest part of the day. Now I expect Martian buildings to be in "heating season" year-round, but this design still helps minimize daily temperature swings that the active HVAC system has to manage. Though I suppose if you had something that needs to get hot only for 4 hours/day in the evening, a western Sun room would be the perfect location.

North glazing is almost entirely heat loss, so it's generally minimized. The north face gets light but little heat, so smaller windows are used because they admit sufficient light while minimizing heat loss.

In summer overhangs are typically used to avoid overheating, and the sloped regolith structures resemble such overhangs. Again I think that surprisingly this consideration will still apply on Mars, because otherwise you overheat in the summer or underheat in the winter, meaning you'd need to oversize your heating or cooling systems. Ideally the building heats and cools itself (itself a nice reliability feature), with the active system being secondary.

Attached is a picture of the BedZED solar development complex. Note how all the buildings are facing the same orientation (south, naturally).

If one is planning to colonize the Southern hemisphere of Mars they'll have to flip my north and south, but otherwise the above should still be valid. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2020 12:53 am
Absolutely, Eat-Ouest with South facing glazing is the way to go.

The angle I chose earlier does not make this obvious and the sun position was more chosen for lighting effect that anything else.
The first image shows the city in it's North at the top orientation.
The second with north at the bottom.
The third from the top with north at the top.

The main north south park/main street sacrifices solar efficiency to create a dramatic variation that highlights the difference between the commercial section and the general housing section. I think the effect is justified and makes the city more livable, but feel free to disagree :-)


Title: Re: Envisioning Amazing Martian Habitats
Post by: MaNaeSWolf on 10/31/2020 09:25 am
These are some nice renders, I presume these are new as I have not seen them before.

We managed to get some "fairly accurate" ground generation into Blender using HIRISE data, if you want I can find out who managed to do that and pass some info on.

I actually dont think farms will care all that much about Orientation. Orientation is more important if you have solid structures that can control light levels. I may run some simulations to see how orientation effects all clear structures, ill update you if I have something.
If your farms are all clear structures, your biggest issue is heat loss at night though. But this is solvable by using waste heat from nuclear power.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2020 12:54 pm
These are some nice renders, I presume these are new as I have not seen them before.

We managed to get some "fairly accurate" ground generation into Blender using HIRISE data, if you want I can find out who managed to do that and pass some info on.

I actually dont think farms will care all that much about Orientation. Orientation is more important if you have solid structures that can control light levels. I may run some simulations to see how orientation effects all clear structures, ill update you if I have something.
If your farms are all clear structures, your biggest issue is heat loss at night though. But this is solvable by using waste heat from nuclear power.
That's the advantage of controlling the renders myself; I can make things up as I go along and answer!
In Surya, the habitats are covered with insulating sheets every night. As greenhouses already use routinely on Earth.  Inertia is such that it's not a dramatic catastrophe of they miss a few nights.  Greenhouses would be less stable.
We also have a fair amount of grow rooms under the habitats and these deliver plenty of waste heat.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2020 01:58 pm
These are some nice renders, I presume these are new as I have not seen them before.

We managed to get some "fairly accurate" ground generation into Blender using HIRISE data, if you want I can find out who managed to do that and pass some info on.

I actually dont think farms will care all that much about Orientation. Orientation is more important if you have solid structures that can control light levels. I may run some simulations to see how orientation effects all clear structures, ill update you if I have something.
If your farms are all clear structures, your biggest issue is heat loss at night though. But this is solvable by using waste heat from nuclear power.
I can get the rough data directly from a NASA Trek site, what I need is the highrise data, and a way of transferring it to either Sketchup or Twinmotion that doesn't create too large a file.  So if you have info would love to hear it!
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 10/31/2020 04:41 pm

That's the advantage of controlling the renders myself; I can make things up as I go along and answer!
In Surya, the habitats are covered with insulating sheets every night. As greenhouses already use routinely on Earth.  Inertia is such that it's not a dramatic catastrophe of they miss a few nights.  Greenhouses would be less stable.
We also have a fair amount of grow rooms under the habitats and these deliver plenty of waste heat.

Nicely done as always!
Working to decrypt the encoded labels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lar on 10/31/2020 05:26 pm
Very cool, congrats to all teams. While I would love to read more and see a link to the final presentation/report of the winning team above, I could not find a pdf of the other team presentations. Are they online?

They'll be published in a book from the Mars Society in the next few months

Presentations of the top 10 will probably be on youtube within a couple of weeks
Did that happen?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 10/31/2020 07:49 pm
Very cool, congrats to all teams. While I would love to read more and see a link to the final presentation/report of the winning team above, I could not find a pdf of the other team presentations. Are they online?

They'll be published in a book from the Mars Society in the next few months

Presentations of the top 10 will probably be on youtube within a couple of weeks
Did that happen?
Yes, most of them are up now, not mine unfortunately ;-)
https://www.youtube.com/user/TheMarsSociety

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 11/01/2020 01:44 am
I actually dont think farms will care all that much about Orientation. Orientation is more important if you have solid structures that can control light levels. I may run some simulations to see how orientation effects all clear structures, ill update you if I have something.

If the simulated buildings weren't designed using passive solar principles, then the simulation will just tell you what you already know -- that without using passive solar design, buildings are incapable of taking full advantage of sunlight.

It's a chicken-and-egg problem. Terrestrial architects today don't design their buildings with a fixed compass direction in mind first, therefore they can't ever really use passive solar features, therefore they never realize why they need to design their buildings with a fixed compass direction in mind first. :) Instead we aim our buildings at the road ("curb appeal") not the Sun, much to the detriment of our comfort, our wallets, and the future habitability of our planet.

Mars is so harsh that we'll need to pull out every trick in the book.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 11/01/2020 06:52 pm
[Lamontagne's renders]
I think Paul451 is suggesting they'd all be oriented in the same direction not due to terrain considerations, but because the buildings looks like they employ passive solar design (IMO a Very Good Idea on such a cold planet), so one would expect the building's long axis to be oriented east-west with the majority of glazing on the south side (because the Sun moves across the southern half of the sky). [...]
this consideration will still apply on Mars, because otherwise you overheat in the summer or underheat in the winter

While you correctly saw the intention of my comment (except with the directions flipped, because I read "southern settlement" as meaning it was in the southern hemisphere.)

However, I was wrong. Turns out Nicholson's crater is in Canada on the Martian equator. "Summer" and "winter" doesn't apply as expected. Instead, you see the apparent path of the sun swing from nearly 30 degrees North to nearly 30 degrees South over 12 months, then back again. There'll still be an optimal use of East/West differences (start-of-day vs end-of-day), but not north/south or summer/winter.

However, with a fairly predictable half the Martian year [edit: second half, if anyone's wondering] more affected by higher atmospheric opacity, due to dust storms, that half of the year will serve as "winter", even for an equatorial settlement, but unrelated to axial tilt.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 11/03/2020 01:07 pm
[Lamontagne's renders]
I think Paul451 is suggesting they'd all be oriented in the same direction not due to terrain considerations, but because the buildings looks like they employ passive solar design (IMO a Very Good Idea on such a cold planet), so one would expect the building's long axis to be oriented east-west with the majority of glazing on the south side (because the Sun moves across the southern half of the sky). [...]
this consideration will still apply on Mars, because otherwise you overheat in the summer or underheat in the winter

While you correctly saw the intention of my comment (except with the directions flipped, because I read "southern settlement" as meaning it was in the southern hemisphere.)

However, I was wrong. Turns out Nicholson's crater is in Canada on the Martian equator. "Summer" and "winter" doesn't apply as expected. Instead, you see the apparent path of the sun swing from nearly 30 degrees North to nearly 30 degrees South over 12 months, then back again. There'll still be an optimal use of East/West differences (start-of-day vs end-of-day), but not north/south or summer/winter.

I mean, there's still optimal use of north/south Sun angle. It's just that the rules for passive solar design in the tropics are different from those in the temperate zones. And you're right, the first thing you learn is about the Sun's motion across the tropical sky, and it's exactly as you described!

The huge difference is that on Earth the tropical zone is a cooling climate, while on Mars the tropical zone remains a heating climate. You're still optimizing for heat gain, not cooling, so everything is reversed from terrestrial tropical designs. It'll really be an interesting architecture to see crystallize, not having exact parallels to anywhere on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/11/2020 08:45 pm
I came across this great concept for inflatable Mars habitats. Lots of interesting and novel design features in this one.

https://www.youtube.com/watch?v=K4dLU3sa9bQ

Ultra-light primary structures

Ultra-light furniture, fixtures, partitions, and other secondary structures

Good attention paid to passive solar design at equatorial latitudes

Mass-efficient pressure vessel geometry

Good radiation shielding

Easy inspection of the primary air bladder


Some people surely won't like the fact that it collapses if deflated, but "you die if you die" isn't a big show-stopper IMHO. Naturally there are multiple ways to add a contingency gravity structure (short of moving to a fully rigid design) if it's a concern to you. No need to re-hash that debate again. :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/11/2020 10:17 pm
Wauw, really a very well thought-out proposal! - It is a little bit let down by the production values of the video but that is secondary.

The more I saw the more I appreciated all the thought that had gone into this. A lot of my qualms about inflatable structures were countered by this design. Could make inflatables a good complement to tunnels, which of course ;-) must be the final goal. You can't build a lasting city from tents and inflatable plastic bubbles but they can be a great beginning.

I couldn't make it out in the beginning but I realised that it is Dyneema ropes they are talking about.

I think a lot of the stuff they talk about should be applied to the interior furnishing of Starship as well. Maybe not so much inflatable structures, but I would love to see the whole interior habitation structure made from high-strength webbing, sail-cloth walls, tensile structures, all highly modulable and redeployable for the very different lift-off, transit and surface conditions encountered during a mission. 

Final thought: please don't make the doors out of pink plastic...
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 12/11/2020 10:35 pm
You can't build a lasting city from tents and inflatable plastic bubbles
Why not?

All our buildings are designed on the assumption that pressure is the same inside and out, so we expect construction to follow a corresponding set of rules.

Why wouldn't Martian construction follow a completely different set of rules, where inflatables are simply the way it is always done?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/11/2020 11:53 pm
Because of the harsh environment on Mars, plastic degradation, thermal cycles and the psychological uncertainty of living in an inflatable sheath secured with strings holding up 1000 tons of regolith. At some point it will just feel better to move into a place with bedrock walls and a big ole stainless steel airlock. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 12/12/2020 12:13 am
Because of the harsh environment on Mars, plastic degradation, thermal cycles and the psychological uncertainty of living in an inflatable sheath secured with strings holding up 1000 tons of regolith. At some point it will just feel better to move into a place with bedrock walls and a big ole stainless steel airlock.
I'm not talking about building cities out of old shopping bags :-) Think of it more like going from wattle-and-daub roundhouses to modern apartment blocks. The materials, techniques and scale will change beyond recognition, but the underlying construction principle remains the same.

As for the psychological effects, people just get used to things. As I'm typing this I made myself think about the weight of the upstairs room and roof above me in my house, and had a little shudder. I have absolutely no understanding of the structural engineering designs & tolerances that are stopping me me being crushed right now, I just trust that the building will do what it is supposed to do.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/12/2020 12:29 am
Picking up on your analogy of going from roundhouses to apartment blocks, I see inflatables vs. bedrock caves a bit as the historical progression from huts to houses to castles. Through the history of humanity there has been a definite progression from flimsier housing to something more solid, as it became possible. I suspect a similar trend will happen on Mars.

I definitely think that well thought-out inflatables such as those envisioned by Thomas Herzig have a place on Mars, which surprises me, because I didn't necessarily think so before.   
Title: Re: Envisioning Amazing Martian Habitats
Post by: oiorionsbelt on 12/12/2020 02:06 am
That's the best cut and cover, side mirrored, inflatable Martian habitat I've ever seen.
Title: Re: Envisioning Amazing Martian Habitats
Post by: KelvinZero on 12/12/2020 04:09 am
You can't build a lasting city from tents and inflatable plastic bubbles
Why not?

All our buildings are designed on the assumption that pressure is the same inside and out, so we expect construction to follow a corresponding set of rules.

Why wouldn't Martian construction follow a completely different set of rules, where inflatables are simply the way it is always done?
I think it would only take a small modification to this idea to avoid the issue anyway. I have seen similar ideas to this that use ice instead of dirt for example, or frozen mud. The SpaceX plan requires early access to a lot of water and it may actually be easier to automate access to water than to dirt, eg my favourite: a Rodrigues well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 12/12/2020 08:41 am
Picking up on your analogy of going from roundhouses to apartment blocks, I see inflatables vs. bedrock caves a bit as the historical progression from huts to houses to castles. Through the history of humanity there has been a definite progression from flimsier housing to something more solid, as it became possible. I suspect a similar trend will happen on Mars.

I definitely think that well thought-out inflatables such as those envisioned by Thomas Herzig have a place on Mars, which surprises me, because I didn't necessarily think so before.
Yeah.

Maybe I should drop the term "inflatable" though. What I really mean is that I think habitable buildings on Mars will always rely more on internal pressure than compressive load-bearing structures for support.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/12/2020 10:10 am
Internal-pressure buildings rely on someone actively maintaining a fine balance in the air pressure, to avoid collapse or bursting. Compressive load-bearing structures are passive, should normally need very little upkeep, and just rely on gravity staying the same. I know what would give me a sound sleep overnight on Mars.

But I repeat, inflatables could very well have a big role to play on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 12/12/2020 11:12 am
Internal-pressure buildings rely on someone actively maintaining a fine balance in the air pressure, to avoid collapse or bursting. Compressive load-bearing structures are passive, should normally need very little upkeep, and just rely on gravity staying the same. I know what would give me a sound sleep overnight on Mars.

But I repeat, inflatables could very well have a big role to play on Mars.
You're absolutely right that relying on pressure means you are relying on actively maintaining the correct internal atmospheric conditions, but they rely on that anyway to stop the inhabitants asphyxiating.  The tolerances for structural support will be a lot wider than the tolerances for not killing the (rather fragile) biologicals which is often measured in parts-per-million.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/12/2020 08:50 pm
Re: Herzig's inflatable house.

Cue my usual rant about 30% oxygen under partial pressure. Especially at Mars gravity. That polymer skin will burn nicely.

(Also, AIUI, dyneema deforms under continuous loads, slowly stretching. Good for sharp, periodic loading, but maybe not ideal for this application?)



Re: Inflatable vs tunnel.

If your ability to maintain air-pressure is not sufficient to keep a roof held up, I would not want you designing my life-support system even if I lived in a solid structure.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/14/2020 11:04 pm
Re: Herzig's inflatable house.

Cue my usual rant about 30% oxygen under partial pressure. Especially at Mars gravity. That polymer skin will burn nicely.

(Also, AIUI, dyneema deforms under continuous loads, slowly stretching. Good for sharp, periodic loading, but maybe not ideal for this application?)



Re: Inflatable vs tunnel.

If your ability to maintain air-pressure is not sufficient to keep a roof held up, I would not want you designing my life-support system even if I lived in a solid structure.

Obviously the fire hazard that you mention, combined with flimsy walls, is another reason why I prefer the idea of rock-solid housing.

It is not a black-and-white question of whether you are able to maintain air pressure. It is a question of whether - if a pressure-related accident happens - you need to worry about the whole structure caving in, in addition to your immediate worry about the air pressure.

I can well imagine an emergency where the colonists will be required to don pressure suits while they repair a leakage. Much preferable to be able to do that in the knowledge that your primary habitat is not about the flatten like a failed soufflé.
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 12/14/2020 11:28 pm
Re: Herzig's inflatable house.

Cue my usual rant about 30% oxygen under partial pressure. Especially at Mars gravity. That polymer skin will burn nicely.

(Also, AIUI, dyneema deforms under continuous loads, slowly stretching. Good for sharp, periodic loading, but maybe not ideal for this application?)



Re: Inflatable vs tunnel.

If your ability to maintain air-pressure is not sufficient to keep a roof held up, I would not want you designing my life-support system even if I lived in a solid structure.

Obviously the fire hazard that you mention, combined with flimsy walls, is another reason why I prefer the idea of rock-solid housing.

It is not a black-and-white question of whether you are able to maintain air pressure. It is a question of whether - if a pressure-related accident happens - you need to worry about the whole structure caving in, in addition to your immediate worry about the air pressure.

I can well imagine an emergency where the colonists will be required to don pressure suits while they repair a leakage. Much preferable to be able to do that in the knowledge that your primary habitat is not about the flatten like a failed soufflé.
I suspect you and I have very different things in mind when we talk about inflatable or pressure-supported buildings  :)

Also, are you aware that we have large pressure-supported public buildings already here on Earth?

https://en.wikipedia.org/wiki/Air-supported_structure#/media/File:Tokyo_Dome_2015-5-12.JPG
Title: Re: Envisioning Amazing Martian Habitats
Post by: DistantTemple on 12/15/2020 12:14 am
Amazing  Twark_Main !!! http://pneumocell.com/  (Edit: spelling)

Someone drag Elon to a demo of this! .... and I need to cash in my pension, and invest in it! A fantastic concept.... and a fantastic guy.
As well as pre made items, (which would be the overwhelming majority) the fabrics etc, and machines could also be taken to Mars to make custom structures, interior features... etc.
Could Thomas Herzig join the crew and go to mars to supervise installation on the ground!
S posted up-thread...
https://youtu.be/K4dLU3sa9bQ (https://youtu.be/K4dLU3sa9bQ)

Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/15/2020 06:03 am
Also, are you aware that we have large pressure-supported public buildings already here on Earth?

https://en.wikipedia.org/wiki/Air-supported_structure#/media/File:Tokyo_Dome_2015-5-12.JPG

I don't think it is necessary to ask me (or anyone in this thread) whether I am aware that we have large pressure-supported buildings on Earth. - Just saying that because I don't think it is pleasant when people descend to LMT-Twark_Main-level insults and snarkiness.

Yes, I am aware. However, those buildings are not surrounded by a hostile radiation environment with an air pressure 1% of that at Earth sea-level. Also they are not an interplanetary distance away from emergency services. I don't think it necessary to mention these obvious facts, but since you asked whether I know about pressure-supported buildings on Earth I thought I would just spell them out.

I'm really sad to see snarkiness beginning to pollute the mutual tone in these forums, so I think those who can keep themselves from doing it should refrain. These forums have been going for a decade + and this thread for several years and just because a small number of members are very disagreeable to each other (so easy with screens interposed) shouldn't mean that all must feel free to be so. To new members I just want to say that such a tone was never the norm in here. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: steveleach on 12/15/2020 08:52 am
Also, are you aware that we have large pressure-supported public buildings already here on Earth?

https://en.wikipedia.org/wiki/Air-supported_structure#/media/File:Tokyo_Dome_2015-5-12.JPG

I don't think it is necessary to ask me (or anyone in this thread) whether I am aware that we have large pressure-supported buildings on Earth. - Just saying that because I don't think it is pleasant when people descend to LMT-Twark_Main-level insults and snarkiness.

Yes, I am aware. However, those buildings are not surrounded by a hostile radiation environment with an air pressure 1% of that at Earth sea-level. Also they are not an interplanetary distance away from emergency services. I don't think it necessary to mention these obvious facts, but since you asked whether I know about pressure-supported buildings on Earth I thought I would just spell them out.

I'm really sad to see snarkiness beginning to pollute the mutual tone in these forums, so I think those who can keep themselves from doing it should refrain. These forums have been going for a decade + and this thread for several years and just because a small number of members are very disagreeable to each other (so easy with screens interposed) shouldn't mean that all must feel free to be so. To new members I just want to say that such a tone was never the norm in here.
Oops, sorry. Snark was not the intent at all; that was a legitimate question because there are an awful lot of people (certainly in the world outside these forums) who don't know these things exist. I was simply trying to rebut the "flimsy" / "souffle" suggestions.

I'll try to be more careful with my wording in future.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/15/2020 09:21 am
OK :-)

Yeah, we have gone over all sorts of imaginable habitats over the years, inflatables, tunnels and many more, but I realise it can perhaps be daunting to read through the 150+ pages of this thread. Most underground dwellings and most types of digging machinery  have been referenced as well.

What I haven't come across in this thread are pressure-supported buildings on Earth holding up several hundred or thousands of tons of weight, in the form of regolith or otherwise. They may exist, and if they do I'd like to know.

There is a big difference between a habitat that will be crushed if the internal air pressure is equalised with ambient air pressure, and a habitat that will keep its shape. The classic "steel can" habitats traditionally shown on the Martian or lunar surface wouldn't deflate if they lost pressure. They would be resealable and repairable by workers in pressure suits.

I think constructions such as Herzig's could be great for farming on Mars. Fine for plants but I'd be nervous about using them for human habitation.

There was mention of support structures that could keep an inflatable up if it were to lose pressure. Well, if such support stuctures are necessary might they not just as well be the primary structure?   
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 12/15/2020 03:26 pm
There was mention of support structures that could keep an inflatable up if it were to lose pressure. Well, if such support stuctures are necessary might they not just as well be the primary structure?

In concepts like Herzig's, the strength required to hold up the roof is much less than required to build a fully rigid structure.

Your criticism only really applies to concepts which propose matching the mass on the roof to the air pressure. (In such ideas, shielding is just a bonus, given that the mass required to balance air pressure is several times greater than required for shielding.)

But even there, it's possible to have at least a partially structural mass that has compressive strength but no tensile strength, that is entirely supported by air pressure when things are working properly but rests on itself when pressure drops. For example, a long arch with sufficient compressive strength to support the roof weight (but virtually no tensile strength), which is lifted slightly off the ground when pressurised, putting its entire weight against air pressure, but doesn't collapse into the living areas when that pressure is lost.

Many materials have vastly higher compressive strength than their tensile strength. Even materials like steel have about four times the compressive strength. Indeed, such a compression-in-emergency structure as I've described could use low grade ISRU steel (or even iron) for compressive supports that wouldn't remotely reliable enough for a "tin can" pressure vessel.

On the flip-side, IMO advocates of bedrock/mountain tunnels are ignoring the effect of air pressure changes on the tunnel. You are varying the loads on the walls by up to ten tonnes per square metre. There's a risk that such massive changes in forces on the walls would cause it to lose structural integrity if the pressure suddenly dropped. Hell, in an unlined tunnel (which seems to be what is envisioned), pieces of the walls/ceilings could come away just from the lack of support underneath. While the rock has ridiculous compressive strength, the inner face of the roof is under tensile loads. While examples of unlined or partially lined underground structures have been shown, those are exceptions that prove the rule, it vastly more common to require a lining which can support and prevent collapse. And "if such support structures are necessary might they not just as well be the primary structure?"
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/15/2020 04:14 pm
There was mention of support structures that could keep an inflatable up if it were to lose pressure. Well, if such support stuctures are necessary might they not just as well be the primary structure?
But even there, it's possible to have at least a partially structural mass that has compressive strength but no tensile strength, that is entirely supported by air pressure when things are working properly but rests on itself when pressure drops. For example, a long arch with sufficient compressive strength to support the roof weight (but virtually no tensile strength), which is lifted slightly off the ground when pressurised, putting its entire weight against air pressure, but doesn't collapse into the living areas when that pressure is lost.

That is an interesting case. Obviously it will be a heavier solution than a pure pressure-supported building, but I guess people would sleep better at night in that one. I imagine something like a Nissen hut steel arched roof with tons of regolith piled on top and the metal arch capable of holding the weight. In the end there will not be much need for a pressure-supported inner bladder underneath, though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/25/2020 12:36 am
I don't think it is necessary to ask me (or anyone in this thread) whether I am aware that we have large pressure-supported buildings on Earth. - Just saying that because I don't think it is pleasant when people descend to LMT-Twark_Main-level insults and snarkiness.

[snip]

I'm really sad to see snarkiness beginning to pollute the mutual tone in these forums, so I think those who can keep themselves from doing it should refrain. These forums have been going for a decade + and this thread for several years and just because a small number of members are very disagreeable to each other (so easy with screens interposed) shouldn't mean that all must feel free to be so. To new members I just want to say that such a tone was never the norm in here.

Don't worry, since blocking LMT a while ago I find my experience much improved. I don't want that unpleasantness in my life just as much as the next person.

I think constructions such as Herzig's could be great for farming on Mars. Fine for plants but I'd be nervous about using them for human habitation.

There was mention of support structures that could keep an inflatable up if it were to lose pressure. Well, if such support stuctures are necessary might they not just as well be the primary structure?   

I think that even if you're using rigid pieces, the form will end up looking similar to this. A shape that works as an inflatable is necessarily a thin-walled pressure vessel, so the shape is "automatically" optimized on that parameter.

I do think there's an opportunity to scale up the Pneumocell form. By stacking vertically as well as horizontally, you get an internal 3D grid structure that can perfectly double as the "skeleton" of an office building-size (or larger) structure, directly attaching the secondary floor structure to the grid.

If the primary grid structure is made of simple I-beams (CFRP or in-situ steel) with periodic cross-bracings, you can start to glimpse a unification between efficient pressure vessel geometry and conventional (inexpensive / low risk) pre-fab steel building construction.

The vast majority of the mass such a structure would be composed of simple cheap I-beams (bigger is better here, per cube-square scaling), with identical pre-fab facing panels (vacuform CFRP or stamped steel) forming the outer hull. These outer panels resist the internal pressure and transfer that force as tension into the 3D grid. A "pillow" geometry for these outer panels minimizes shear and stress concentrations, while still filling the square and/or rectangular void.

If the 6-way I-beam "connectors" are accessible from the outer hull, this would allow for "online" expansion of the structure without depressurizing existing habitat areas. It would also provide a hardpoint to anchor regolith radiation shielding "reinforced earth" outer walls, which will be quite massive and must remain stable through Marsquakes.

If we assume square geometry for maximum commonality, the primary structure of the habitat could consist of only three unique parts: the I-beams, the connectors, and the outer pressure panels. The outer panels could be shipped in stacks like bowls, and the I-beams and connectors should pack down reasonably as well. Add in the secondary structure floor segments, and with these four components you can construct efficient, extensible pressure vessels of ~unlimited size with more-or-less arbitrary rectilinear shapes, not constrained at the large end to becoming giant spheres or cylinders.

Hopefully this germ of an architectural system starts to answer the (till now mostly ignored) second question in the opening post:

What selection of habitat building components would you want in your flat-packed containers?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/25/2020 12:33 pm
Using soap bubbles is a great way of finding the optimal minimal-tension structures that can be made with inflatables. Danish architect Johan Otto von Spreckelsen and engineer Erik Reitzel did experiments with soap bubbles which led directly to the Grande Arche in Paris, built in the late 1980s. The Grande  Arche is a "hyper cube", a cube within a cube. For its shape it uses a minimal number of surfaces, all of a minimal size. Normally, you would have to calculate quite complex differential equations to find the optimal shape, but soap bubbles do it automatically by descending to the minimal energy state.

(I personally met Reitzel at the Grande Arche in the early 90s and discussed its construction with him...)

   
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/26/2020 03:20 am
Using soap bubbles is a great way of finding the optimal minimal-tension structures that can be made with inflatables.

A Mars inflatable would have high volumetric stiffness, resisting volume change.  It's an important factor in the structure's stiffness matrix. 

How could soap-bubble analogy give the optimal structural form, or even plausible form, when bubbles lack volumetric stiffness?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/31/2020 08:08 pm
Using soap bubbles is a great way of finding the optimal minimal-tension structures that can be made with inflatables.

A Mars inflatable would have high volumetric stiffness, resisting volume change.  It's an important factor in the structure's stiffness matrix. 

How could soap-bubble analogy give the optimal structural form, or even plausible form, when bubbles lack volumetric stiffness?

A pneumatic form-finder applies gas law; this adds volumetric stiffness to the stiffness matrix, giving realistic structural form and stress.

Easy.Vol (https://www.technet-gmbh.com/en/products/easy/calculation-of-pneumatic-structures/) is one such commercial app.  Does public-domain code exist?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/31/2020 08:59 pm
The fear of being crushed is valid. That’s why I’m a fan of water for shielding. If insulated on the outside or if salts are added, it can remain liquid. That means of the structure starts to collapse, the water can be released (at a somewhat controlled rate) to relieve the force on the hab and give time to repair the damage.
It’s a bit more complicated and has risk of inundation, but better than being flattened and allows a lightweight tensile dominated structure to be used. Also, clear radiation shielding allows in light!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/23/2021 12:23 am
This might be helpful to those interested in cheaply manufacturing efficient pressure vessel geometries, possibly in-situ.

https://www.youtube.com/watch?v=Sk9WyEfzWPg

Anyone know if this can work using appropriately placed thin-film methalox balloons?

Bonus shot:
https://www.youtube.com/watch?v=j3IXhQiQbZ4
Title: Re: Envisioning Amazing Martian Habitats
Post by: Keldor on 01/23/2021 12:47 am
This might be helpful to those interested in cheaply manufacturing efficient pressure vessel geometries, possibly in-situ.

https://www.youtube.com/watch?v=Sk9WyEfzWPg

Anyone know if this can work using appropriately placed thin-film methalox balloons?

Bonus shot:
https://www.youtube.com/watch?v=j3IXhQiQbZ4

That's pretty cool, but what do you gain from doing this, other than nice smooth walls?  I guess the tank won't change shape any more when you fill it for the first time after mounting it wherever it goes?
Title: Re: Envisioning Amazing Martian Habitats
Post by: DasBlinkenlight on 01/23/2021 02:42 am
I wonder if the "inflatable concrete" concept could be adapted... basically the the inflatable membrane has a coating on it that "turns to concrete" when wetted.  (Granted water may be the long pole in the tent.

Here is an example:
https://combatconcrete.com/ (https://combatconcrete.com/)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/23/2021 03:13 am
I wonder if the "inflatable concrete" concept could be adapted... basically the the inflatable membrane has a coating on it that "turns to concrete" when wetted.  (Granted water may be the long pole in the tent.

Here is an example:
https://combatconcrete.com/ (https://combatconcrete.com/)
Why? Water is pretty plentiful on Mars compared to cement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/14/2021 11:03 pm
This might be helpful to those interested in cheaply manufacturing efficient pressure vessel geometries, possibly in-situ.

[video1]

Anyone know if this can work using appropriately placed thin-film methalox balloons?

Bonus shot:
[video2]

That's pretty cool, but what do you gain from doing this, other than nice smooth walls?  I guess the tank won't change shape any more when you fill it for the first time after mounting it wherever it goes?

The advantage is that you can make thin-walled spherical pressure vessels without big investments in production machinery. The "angular" shape has stress concentrations at the corners (for holding pressure that's Bad, just ask the de Havilland Aircraft Company (https://en.wikipedia.org/wiki/De_Havilland_Comet)), but the smooth spherical shape has nice uniform stress everywhere.

Normally spherical vessels are prohibitive (despite requiring half as much material as cylindrical pressure vessels) because it's hard to make the thick doubly-curved metal without a huge stamping press.

Since every habitable building on Mars will be a pressure vessel, this has obvious applicability beyond just storage tanks.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 03/15/2021 07:44 pm
Last year's Nexus Aurora team report (https://nexusaurora.com/report.pdf) had some creative hab ideas.

Water:  They use water as a radiation shield, but they neglect the role of water pressure in architecture.  Much could be done with that.  E.g., given sufficient water mass, many of their "steel tensile rods" could be removed when extraneous, opening the space.

Steel:  Their steelmaking process is a bit curious.  They assume iron reduction is needed; however, on Mars much accessible iron ore is already in reduced, metallic form, as we've seen e.g. in photos of shiny iron meteorites on Mars.  Oxidation state is therefore a first selection criterion of martian ore deposits.  So they've made a process mistake, applying a terrestrial ore processing method where it shouldn't be needed.

PGMs:  Their furnace is underutilized.  Typical meteorite furnace waste would be rich in unmelted PGMs (https://forum.nasaspaceflight.com/index.php?topic=45772.msg1859890#msg1859890), priced up to $800,000 per kg today (rhodium).  They imagine steel would be the #1 early export -- but what did they overlook?

Images:  Nexus Aurora
Title: Re: Envisioning Amazing Martian Habitats
Post by: Aria-Nikson on 03/27/2021 10:24 am
Amazing  Twark_Main !!! http://pneumocell.com/  (Edit: spelling)

Someone drag Elon to a demo of this! .... and I need to cash in my pension, and invest in it! A fantastic concept.... and a fantastic guy.
As well as pre made items, (which would be the overwhelming majority) the fabrics etc, and machines could also be taken to Mars to make custom structures, interior features... etc.
Could Thomas Herzig join the crew and go to mars to supervise installation on the ground!
S posted up-thread...
https://youtu.be/K4dLU3sa9bQ (https://youtu.be/K4dLU3sa9bQ)

Yes it looks really cool
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 04/11/2021 12:47 am
I understand the utility of water as a shield. i understand that inflatables can be made of a transparent material to allow light in.  However, neither water nor curved materials are useful for providing external vistas.  I think that clarifying the purpose of the components is important here.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 04/13/2021 06:47 pm
I understand the utility of water as a shield. i understand that inflatables can be made of a transparent material to allow light in.  However, neither water nor curved materials are useful for providing external vistas. ...

How so?

The simplest design (but by no means the only possible design) just has two inflatable transparent spheres with water in-between, forming an above-ground "golf ball" dome.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ice on 04/21/2021 02:48 pm
4K resolution versions of those SimCity-style Mars Base Alpha buildup images in Elon's September 2017 BFR presentation: https://www.humanmars.net/2021/04/spacex-mars-base-alpha-in-4k-uhd-quality.html
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/01/2021 01:38 am

Toward a CO2 Grid: Efficient Recycling of Latent/Sensible/Process Heat and CO2 Distribution Using Microgrids


This started off as a simple idea, I swear. "What if in your Mars habitat, along with electricity/data/water lines, you ran CO2 through high and low pressure pipes for refrigeration? That is, what if you made a CO2 Grid?" The whole thing snow-balled from there.

A little background: supercritical CO2 can be used in refrigerators as the fluid (appropriately enough, the 'refrigerant'). It replaces our current HFCs, which replaced the dreaded CFCs, which replaced the deadly anhydrous ammonia. Like HFCs, CO2 doesn't deplete the ozone layer. But CO2 has far less global warming impact, since most HFCs are super greenhouse gases that cause 100s-to-1000s of times more warming per ton than CO2. Paradoxically on Mars we want warming, but any imported tonnage would be trivial toward that effort, and synthesis on Mars is non-trivial.

CO2 is the natural refrigerant for Mars. It's trivially and abundantly available with no synthesis required. There's no need for contingency stockpiles in case the precious imported refrigerant (with no available Mars substitute) leaks away. And CO2 has better thermodynamic cycle efficiency than traditional refrigerants like R-134A, so you need less electrical energy and power for heating and cooling. Good so far.

The snowball started rolling when I realized this CO2 grid can distribute CO2 to plant growth chambers, either scattered around the colony or a grid layout within a large-scale chamber, each grid cell with its own dehumidifier and sensors. In these dehumidifiers, the pressurized CO2 doesn't drive a motor. Far too complicated. Instead the CO2 simply expands through a valve (getting cold) and then flowing through an evaporator in an open-cycle refrigeration system. This CO2 can be dumped to the atmosphere, or the low-pressure CO2 line. This hardware is highly simplified, deleting the dehumidifier's motor, compressor and condenser, and leaving only the expansion valve and the evaporator. Nice.

This is only possible because we're relying on an external source of pressurized CO2, originally a centralized compressor. But more on that later.

The snowball got away from me when I realized I could do the same trick backwards and in heels. The same grid can provide on-demand heating (hot water, space heating, low-grade process heat) by using the other half of the heat pump. The compressor pumps CO2 from low to high pressure, and the condenser provides heat the load (either using an air-to-air or air-to-water design). This has some advantages over self-contained heat pump units. The condenser and its fan are eliminated which reduces mass, volume, and cost. The heat pump is performing useful mechanical work (pumping from low to high pressure). Most importantly, this work lets us do chilling & dehumidification needed elsewhere "for free."[1]

In thermodynamic terms, we've built a network which recycles and transports heat around, recovering heat from cooling loads and supplying heat to heating loads. What's remarkable is that we're circulating fluid at or near ambient temperature, eliminating heat loss and thermal insulation (lowering cost, mass, and volume). This is a huge improvement over traditional piped hot water "district heating" systems, which require thick insulation, causes unwanted heating in corridors and utility areas, and delivers uneven heating due to temperature drops.[2]

"But Mars is cold," you say, "why do I need cooling?" If you're going to have people and/or plants, you're gonna need a lot of dehumidification, which essentially the same thing as cooling[3]. Most buildings in cold climates rely on moisture simply escaping to the outside, which isn't a great option on Mars. Additionally, about 50% of the light striking a leaf is used to evaporate water. This isn't as inefficient as it sounds -- it means every square centimeter of leaf area is doing double-duty as a self-cleaning,  evaporator surface. If you know anything about the anti-fouling maintenance (and resupply) these surfaces require in full-tilt water distilling operation, you know that's a Very Good Thing.

Side rant: this water recycling function of plants (which is typically dismissed as "inefficiently wasted photon energy") is responsible for almost all the rain that falls on Earth's land surface area. (https://www.nature.com/articles/nature11983) Without plants, all the evaporated ocean water would rain out within a couple hundred miles of shore, running via rivers back into the ocean. With plants, the soil (also created and maintained by plants) soaks up the water before it runs off, and the plants (mainly trees, but also prairie grass) drink it up and pump it back into the atmosphere, where it rises by buoyancy and rejects IR directly into space. Basically forests are blowing on and "fogging up" a cold window, except that window is the top of Earth's atmosphere[4]. So without forests and prairies, we'd be trucking and/or piping water in from the coasts! That's true inefficiency right there, on a mind-boggling, nation-bankrupting scale. Goodbye "bread basket of America," along with most other similar regions around the world. End rant. ::)

If you should feel a sudden and inexplicable urge to start monthly donations to the Audubon Society, their website is over here: https://www.audubon.org (https://www.audubon.org)


Back to the CO2 grid. Now the snowball is chasing me like Indiana Jones.

About that centralized compressor mentioned earlier? It's a good option (and a great backup), but it generates a lot of heat (the last thing we need in the middle of our giant farm-scape). What if we generate that heat a little closer to where it's needed? Can one problem solve another?

We're already compressing atmospheric CO2 for plants and rocket fuel. If this ISRU system is configured to feed Martian CO2 into the low-pressure side, not the high pressure reservoir, CO2 compression could be one of the colony's major heat sources. A district heating system to distribute this heat throughout the colony would have a high cost. Instead we can distribute the compressor system itself throughout the colony.

Raw Mars atmosphere would still need to be filtered and pumped up to the LP side pressure, so some dedicated ISRU pumps are still needed. However these pumps would require less energy and create less waste heat. The remainder of the waste heat is distributed "for free" throughout the colony by activating compressors colocated with heating loads. Naturally this would use an Tesla AutoBidder-like system with real-time prices (one price for electricity and another which combines heating, cooling and CO2 supply) to forecast supply and demand and maximize network efficiency. Cold night? Extra CO2 gets pumped in to supply the additional heating demand. Suddenly get a big bump in CO2 demand for plastic production? Magically everyone's thermostats get bumped up by 1 degree. :P

The snowball is now careening down the street like Katamari, picking up cars and people.

What if you have lots of demand for heat, but not much demand for CO2? The CO2 reservoir get full... and then what? That's right, snow day! Just pop the vent and watch the supercritical CO2 flash-freeze into dry ice snow, settling gently on the ground. Beautiful of course, but sounds inefficient right? Not really. All we "wasted" is electricity, and we're not really wasting it, we're using it to pump heat into the hab. To put it in refrigeration terms, we're supplying the compressor and condenser and Mars is supplying the evaporator. More important, remember that the alternative is to build a big field of radiator panels or a big array of atmospheric heat exchangers. In a way we're heating the same way trees cool themselves -- by exploiting one-way[5] mass transfer to the environment. Just chuck out some (abundant and easily replaced) mass and let that be your heat exchanger instead. Clever girl.

So finally at long last, the snowball analogy comes full-circle. :)

Let's talk down-sides. As we usually see in engineering, there's a trade-off here between raw efficiency and robustness. A unified system is more vulnerable to leaks and cascading failures, of course. I expect these issues would be mitigated by adding valves (airplane hydraulics are a good place to start), backing up critical thermal loads with standalone systems, limiting maximum system size (microgrids), and in some cases using A and B loops -- a thermal analog to Apollo's famed Main Bus A and Main Bus B electrical systems.



So in summary, what have we accomplished here? We're keeping warm by recycling heat from greenhouses and compressors. We're intelligently combining thermal and raw material transport in the same system ("best part is no part"). We're simplifying our chiller and dehumidifier hardware dramatically. And we're deleting huge fields of radiators by using the Mars atmosphere as a giant open-loop heat pump.

Come to think of it, this is starting to sound familiar... (https://www.inverse.com/innovation/tesla-hvac-musk-plan)



[1] that is, for the cost of connecting it to the grid
[2] Another advantage over district heating is supplying heat at a variety of temperatures. This has thermodynamic limits of course, based on the two pressures chosen. In district heating the system design is "tuned" by varying the high and low temperatures, whereas here you vary the high and low pressures.
[3] real refrigeration experts are catatonic upon hearing this egregious abuse of terminology
[4] trees also contribute to the air stream cloud-seeding bacteria that live on their leaves, causing 70-100% of all raindrop nucleation (https://science.sciencemag.org/content/319/5867/1214)
[5] technically it's two-way transfer because in both cases the material stays within the atmosphere and gets recycled over long time-scales, but point being no resources are spent building a dedicated "return line"
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 05/01/2021 01:43 am

A few more points on CO2 Grids. Naturally there's many possible variations on the design.

You might delete the low-pressure side entirely and use the outside atmosphere instead. Not sure if this could work, since the Mars atmosphere isn't pure CO2.

You can combine a lot of the parts in the same cabinet. I expect Tesla HVAC will be an engineering master-class in this, so I'll be very interested to see the first leak and/or teardown. :)

Naturally you need dust filtering for the CO2 intake compressor. Pre-assembled filter cartridges need lots of maintenance (and on Mars, resupply mass), so most Earth-bound industries use a baghouse. Wikipedia has the deets (https://en.wikipedia.org/wiki/Baghouse), but basically it's a big box with long cylindrical filter bags hanging inside and a lower hopper to catch the dust. There's a few different designs depending on how it "shakes off" the dust, but I favor pulsed air -- dust clings to the outside of the bag, which is held open by built-in rings (on Mars these might be removed from worn-out bags and reused, eg split rings that slide into a "drawstring hoodie" channel). Above each bag is a nozzle which shoots a pulse of compressed air down the bag, generating a wave that shakes off the dust.

Cool? Yes, but also practical. This cleaning method leads to the longest bag life, it allows online cleaning, and it's mechanically simple. It can be operated by a single valve that can be located well away from the dust, and only exposed clean gas flows through it. And since it's the only design sucking dirty air *into* the bag, and since the dust is already everywhere outside (we're not protecting the public from industrial dust), *you don't actually need the 'house' enclosure around the baghouse*. By Grabthar's Hammer, what a savings! This also eliminates EVAs or mechanical systems to empty dust from the baghouse hopper. Just hang a reinforced PTFE curtain to shade the bags from UV, funneled at the bottom and weighed down with sandbag "pockets." Maintenance is reduced to periodic bag replacement (minimized by the pulsed air design) and pushing the dust pile aside every few months with an RC skid-steer.

After filtration we need to selectively freeze out the CO2. Fortunately this is just another cooling load on the CO2 Grid system. :) Of course we'll recycle the heat inside the hab. Of course freezing out the CO2 will be more efficient if done at night, so I'm starting to think a big fraction of the CO2 intake for ISRU will happen during the coldest parts of the night. We may be be waking up to crunchy, fresh-fallen dry-ice snow on Mars-mas morning. ;D

Thanks for reading, and Happy Holidays!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 05/01/2021 11:01 am
I like the concept. CO2 could be a utility product distributed to habitats and workplaces in a Martian village, along with clean water, clean air, and electricity.

Naturally you need dust filtering for the CO2 intake compressor. Pre-assembled filter cartridges need lots of maintenance (and on Mars, resupply mass), so most Earth-bound industries use a baghouse. Wikipedia has the deets (https://en.wikipedia.org/wiki/Baghouse), but basically it's a big box with long cylindrical filter bags hanging inside and a lower hopper to catch the dust. There's a few different designs depending on how it "shakes off" the dust, but I favor pulsed air -- dust clings to the outside of the bag, which is held open by built-in rings (on Mars these might be removed from worn-out bags and reused, eg split rings that slide into a "drawstring hoodie" channel). Above each bag is a nozzle which shoots a pulse of compressed air down the bag, generating a wave that shakes off the dust.
We don't yet know whether baghouse filters will work on Mars like they do on Earth.

This is because airborne particles on Mars are microscopic in size and partly consist of individual molecules. This is how iron oxide particles are entrained in the atmosphere and give the planet its red hue. This phenomena does not occur on Earth because tiny particles are easily removed from air by rainfall. So Mars airborne particles may pass right through the pores of air filters.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Vultur on 05/02/2021 05:46 am
So Mars airborne particles may pass right through the pores of air filters.

Would MOXIE provide useful insight here, or is the scale / type of filter too different?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 05/02/2021 12:05 pm
So Mars airborne particles may pass right through the pores of air filters.

Would MOXIE provide useful insight here, or is the scale / type of filter too different?
That's a good thought. NASA knows what they are doing and maybe we will know something. (Mars oxygen experiment (MOXIE) on Perseverance rover requires clean atmosphere filters to operate properly.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 05/02/2021 01:06 pm
CO2 has been used as a refrigerant (R744) for a long time, and is starting to make a comeback as a non-CFC alternative, so there's plenty of knowledge on it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 05/02/2021 02:04 pm

A few more points on CO2 Grids. Naturally there's many possible variations on the design.

You might delete the low-pressure side entirely and use the outside atmosphere instead. Not sure if this could work, since the Mars atmosphere isn't pure CO2.

You can combine a lot of the parts in the same cabinet. I expect Tesla HVAC will be an engineering master-class in this, so I'll be very interested to see the first leak and/or teardown. :)

Naturally you need dust filtering for the CO2 intake compressor. Pre-assembled filter cartridges need lots of maintenance (and on Mars, resupply mass), so most Earth-bound industries use a baghouse. Wikipedia has the deets (https://en.wikipedia.org/wiki/Baghouse), but basically it's a big box with long cylindrical filter bags hanging inside and a lower hopper to catch the dust. There's a few different designs depending on how it "shakes off" the dust, but I favor pulsed air -- dust clings to the outside of the bag, which is held open by built-in rings (on Mars these might be removed from worn-out bags and reused, eg split rings that slide into a "drawstring hoodie" channel). Above each bag is a nozzle which shoots a pulse of compressed air down the bag, generating a wave that shakes off the dust.

Cool? Yes, but also practical. This cleaning method leads to the longest bag life, it allows online cleaning, and it's mechanically simple. It can be operated by a single valve that can be located well away from the dust, and only exposed clean gas flows through it. And since it's the only design sucking dirty air *into* the bag, and since the dust is already everywhere outside (we're not protecting the public from industrial dust), *you don't actually need the 'house' enclosure around the baghouse*. By Grabthar's Hammer, what a savings! This also eliminates EVAs or mechanical systems to empty dust from the baghouse hopper. Just hang a reinforced PTFE curtain to shade the bags from UV, funneled at the bottom and weighed down with sandbag "pockets." Maintenance is reduced to periodic bag replacement (minimized by the pulsed air design) and pushing the dust pile aside every few months with an RC skid-steer.

After filtration we need to selectively freeze out the CO2. Fortunately this is just another cooling load on the CO2 Grid system. :) Of course we'll recycle the heat inside the hab. Of course freezing out the CO2 will be more efficient if done at night, so I'm starting to think a big fraction of the CO2 intake for ISRU will happen during the coldest parts of the night. We may be be waking up to crunchy, fresh-fallen dry-ice snow on Mars-mas morning. ;D

Thanks for reading, and Happy Holidays!

Some interesting ideas that makes a lot of sense. The whole concept could also potentially be built into a power storage system as well. There are companies working on something vaguely similar on Earth such as Highview power’s cryo battery. Just use Supercritical / solid CO2 rather than air.

https://highviewpower.com/news_announcement/highview-power-unveils-cryobattery-worlds-first-giga-scale-cryogenic-battery/ (https://highviewpower.com/news_announcement/highview-power-unveils-cryobattery-worlds-first-giga-scale-cryogenic-battery/)

It could also be profitably employed in conjunction with other processes for increased efficiency. So for example nitrogen will be needed on Mars and if you were in the business of filtering, compressing and expanding Martian atmosphere for temperature regulation it seems entirely reasonable that some sort of nitrogen extracting side line could be squeezed into the loop somewhere, especially if the low pressure side was vented to the atmosphere.

There are many options with filtration and my favorite would be some form of cyclone blower to remove dust centrifugally.

There are also some other interesting options concerning compression of the CO2. May favorite here is Temperature Swing Adsorption technology, might also work to help separate out the nitrogen:
https://ttu-ir.tdl.org/handle/2346/84464 (https://ttu-ir.tdl.org/handle/2346/84464)
https://pubs.acs.org/doi/10.1021/acs.iecr.5b01384 (https://pubs.acs.org/doi/10.1021/acs.iecr.5b01384)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/02/2021 05:30 pm
I like the concept. CO2 could be a utility product distributed to habitats and workplaces in a Martian village, along with clean water, clean air, and electricity.

Naturally you need dust filtering for the CO2 intake compressor. Pre-assembled filter cartridges need lots of maintenance (and on Mars, resupply mass), so most Earth-bound industries use a baghouse. Wikipedia has the deets (https://en.wikipedia.org/wiki/Baghouse), but basically it's a big box with long cylindrical filter bags hanging inside and a lower hopper to catch the dust. There's a few different designs depending on how it "shakes off" the dust, but I favor pulsed air -- dust clings to the outside of the bag, which is held open by built-in rings (on Mars these might be removed from worn-out bags and reused, eg split rings that slide into a "drawstring hoodie" channel). Above each bag is a nozzle which shoots a pulse of compressed air down the bag, generating a wave that shakes off the dust.
We don't yet know whether baghouse filters will work on Mars like they do on Earth.

This is because airborne particles on Mars are microscopic in size and partly consist of individual molecules. This is how iron oxide particles are entrained in the atmosphere and give the planet its red hue. This phenomena does not occur on Earth because tiny particles are easily removed from air by rainfall. So Mars airborne particles may pass right through the pores of air filters.
Some redesign for baghouses will be required.  On Earth, fans are after the filters, and create a low pressure that sucks the dust through the dust collector tubes and cake.  So effectively it's that atmospheric pressure that pushes the air through the filtration media.  At 15 psi 101 kPa, there is plenty of pressure available.  At 60 Pa, or 0,24 inches of water, the air will not go through the media; in baghouse these have pressure drops of 4-6 inches, or almost 1 kPa.  For regular filters in HVAC units, the pressure drop is usually 20-30 Pa to start, and then climbs to about 240 Pa when you replace the filter.
So for a small unit like Moxie you can simply oversize the filters, but for a large industrial unit I would expect that the fans would need to be on the outside of the filters, and push through the filters, rather than pull.  Electrostatic filters might be sufficient though, as these usually have low pressure drops, or again these might be after the fans as well.
https://marspedia.org/Dust_collector
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/02/2021 05:47 pm
On the subject of CO2 use in the settlement, it seems an interesting idea.  However, a few points that need to be explored:

1- The work required by compressors to remove the humidity in grow rooms on Earth is extremely high, much higher than for the usual comfort applications.  So perhaps the CO2 cycle would be better for this. 
2-We might just want to use a water cooled cycle, or even better a liquid cycle that is not susceptible to freezing, and avoid compression altogether.  After all, the Martian environment is significantly cooler than the settlement, while compression systems are used on Earth because the environment is warmer that the areas that are being cooled.
3- We would need to analyze radiator dimensions vs work of compression and power sources required to get a real feel for costs. 

4- CO2 in the fuel/atmosphere production cycle: https://marspedia.org/Atmospheric_processing
Title: Re: Envisioning Amazing Martian Habitats
Post by: Vultur on 05/02/2021 08:22 pm
That's a good thought. NASA knows what they are doing and maybe we will know something. (Mars oxygen experiment (MOXIE) on Perseverance rover requires clean atmosphere filters to operate properly.)

This is really my main interest in MOXIE. I doubt SpaceX will use the same chemical process, but learning about working with the Mars atmosphere might transfer.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/03/2021 05:11 pm
At 15 psi 101 kPa, there is plenty of pressure available.  At 60 Pa, or 0,24 inches of water, the air will not go through the media; in baghouse these have pressure drops of 4-6 inches, or almost 1 kPa.  For regular filters in HVAC units, the pressure drop is usually 20-30 Pa to start, and then climbs to about 240 Pa when you replace the filter.

Typical Mars surface pressure is 600 Pa.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/03/2021 05:15 pm
2-We might just want to use a water cooled cycle, or even better a liquid cycle that is not susceptible to freezing, and avoid compression altogether.  After all, the Martian environment is significantly cooler than the settlement, while compression systems are used on Earth because the environment is warmer that the areas that are being cooled.

OTOH, heat-pumps are stupidly efficient when the hot-side has a proper cold sink. You might not be saving anything using only passive (sensible) cooling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 05/03/2021 05:31 pm
That's a good thought. NASA knows what they are doing and maybe we will know something. (Mars oxygen experiment (MOXIE) on Perseverance rover requires clean atmosphere filters to operate properly.)

This is really my main interest in MOXIE. I doubt SpaceX will use the same chemical process, but learning about working with the Mars atmosphere might transfer.
Plenty of options with filters to choose from such as centrifugal and electrostatic as well as physical filtration.

I would expect SpaceX to use MOXIE, but only on a small scale to balance oxygen demand if an oxygen surplus is required. 3.5:1 methane : oxygen ratio used by Raptor and oxygen required for breathing by the crew will mess with the neat stoichiometric proportions produced by electrolysis / Sabatier.  Better to have a small MOXIE unit for excess oxygen production that to waste hydrogen via additional electrolysis.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/03/2021 05:50 pm
At 15 psi 101 kPa, there is plenty of pressure available.  At 60 Pa, or 0,24 inches of water, the air will not go through the media; in baghouse these have pressure drops of 4-6 inches, or almost 1 kPa.  For regular filters in HVAC units, the pressure drop is usually 20-30 Pa to start, and then climbs to about 240 Pa when you replace the filter.

Typical Mars surface pressure is 600 Pa.
Oups!  doesn't change the main conclusion but does make some level of filtration possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 05/03/2021 05:57 pm
2-We might just want to use a water cooled cycle, or even better a liquid cycle that is not susceptible to freezing, and avoid compression altogether.  After all, the Martian environment is significantly cooler than the settlement, while compression systems are used on Earth because the environment is warmer that the areas that are being cooled.

OTOH, heat-pumps are stupidly efficient when the hot-side has a proper cold sink. You might not be saving anything using only passive (sensible) cooling.
Yes, there is a trade off to look at.  And there is the question of the air temperature at the Martian equator that can be high during the day, plus the very low temperature during the night.  The obvious time to cool is during the night, but then most of your processes are stopped.  Accumulating heat is always expensive, so all in all I don't really know what is best.  There should be some much lower pressure fluids than CO2 though, if we use passive cooling. 
Synergies always look good at first, then you start digging and then the advantages often grow marginal in regards of the costs.  Somewhere it will eventually go back to the cost of solar on Mars, or the cost of nuclear, whichever is chosen.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 05/13/2021 06:25 pm
Toward a CO2 Grid: Efficient Recycling of Latent/Sensible/Process Heat and CO2 Distribution Using Microgrids

AIUI, in order for the liquid CO2 refrigerant to be piped around at habitat-temperatures, it would need to be at very high pressure (130atm according to wikipoo), which increases the mass and complexity of the refrigeration system (and the risk of leaks), perhaps enough to rule out a wide scale grid system?


However, re: dust. There might be a hybrid between having to build low-pressure return plumbing and using ambient (dusty) air. Many proposals for small habs use layers of contained CO2 to act as an insulating barrier. Ideally, three layers, first a water layer around the habitat shell to give thermal mass, then a layer of CO2 at a pressure similar to the habitat, then an outermost layer of ambient Mars-pressure CO2. It's possible that larger settlements will also use the same kind of insulating CO2 layers.

One of those layers could serve as a "free" low-pressure return loop, since you already have an envelope running around the entire settlement. Thus the system can eject the expanded CO2 from the cooling loop directly out into the CO2 envelope, while elsewhere the compressor(s) use the same layer of CO2 as their source. You only need to filter the dust and other gases once, when you fill the layer(s) (and replace inevitable leaks. But leak replacement should be a small part of the amount of CO2 being used for the ISRU propellant production, so won't add any additional requirements.)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ice on 02/12/2022 04:07 pm
New Mars Base Alpha design renders from Elon's Starship update presentation in Thursday:
https://www.humanmars.net/2022/02/elons-latest-vision-for-mars-base-alpha.html (https://www.humanmars.net/2022/02/elons-latest-vision-for-mars-base-alpha.html)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/12/2022 04:46 pm
Yes, I saw those. Aspirational, I think is the word Elon uses...  :-)

That cupola would need some humunguous anchors to not fly off. I don't even know if it could be done. The tension loads on the structure would be huge. But perhaps with thick and heavy enough glass? Locally produced of course...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Zed_Noir on 02/13/2022 03:43 am
Yes, I saw those. Aspirational, I think is the word Elon uses...  :-)

That cupola would need some humunguous anchors to not fly off. I don't even know if it could be done. The tension loads on the structure would be huge. But perhaps with thick and heavy enough glass? Locally produced of course...
Think it is more a dome like structure. There is no need for humunguous anchors if you consider it more like a grounded airship with plenty of internal ballast.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/13/2022 04:31 am
Yes, I saw those. Aspirational, I think is the word Elon uses...  :-)

That cupola would need some humunguous anchors to not fly off. I don't even know if it could be done. The tension loads on the structure would be huge. But perhaps with thick and heavy enough glass? Locally produced of course...
I think the anchor thing is no actual problem. Just do it.

I have no idea why this thread seemed to come to the consensus that it wasn’t feasible. It’s not harder than anything else.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/13/2022 05:34 am
Yes, I saw those. Aspirational, I think is the word Elon uses...  :-)

That cupola would need some humunguous anchors to not fly off. I don't even know if it could be done. The tension loads on the structure would be huge. But perhaps with thick and heavy enough glass? Locally produced of course...
I think the anchor thing is no actual problem. Just do it.

I have no idea why this thread seemed to come to the consensus that it wasn’t feasible. It’s not harder than anything else.

Yep. LNG silos are pressurised to 0.6bar and have a flat bottom. It is not Earth shattering, it just requires more construction material.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/13/2022 10:14 am
Any LNG silos pressurised to 0.6 bar placed in a near-vacuum?
Title: Re: Envisioning Amazing Martian Habitats
Post by: tbellman on 02/13/2022 12:44 pm
Any LNG silos pressurised to 0.6 bar placed in a near-vacuum?

Irrelevant.  The 0.6 bar is presumably gauge pressure, i.e. relative to the ambient (outside) pressure, and that's what matters.

However,

A dome by itself does not have a bottom; it is open.  It thus cannot contain any overpressure, by itself.  It needs to be connected to a "floor" to form a pressure vessel (with a gastight connection along the dome's entire perimeter, of course).  And the typical science fiction "domed city" at least seem to use the planetary surface directly as their bottom half.  That's where the problem comes: planetary surfaces don't have very high tensile strength.  E.g, a 50m diameter dome filled with an overpressure of 0.3 bar, will need an anchoring force of 37.5 kN for every decimeter of its perimeter, or the equivalent of the weight of 10 tonnes on Mars.  And this grows linearly with the diameter of the dome, so a 75m dome will need to be anchored by 56 kN/dm, and a 200m dome needs 150 kN/dm of anchoring.

The alternative is to build your own "floor" out of e.g. steel, and weld the dome to that, forming a pressure vessel.  But if that floor is flat all the way out to the perimeter, and form a sharp angle at the connection to the dome, you will need a very strong weld.  It is almost certainly easier and cheaper to make that connection rounded, just like you design any normal pressure vessel.

You can make most of the floor flat, especially if you weigh it down with a few meters of regolith or other heavy filling material on the inside (and you probably want that anyway for other reasons).  But the "corner" where it connects to the dome should be rounded.

You may end up with a structure that when viewed from the outside surface, looks like a dome, but that would be because you only see the dome part of the structure; in reality it would be a full pressure vessel, and be designed and shaped like one.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/13/2022 01:15 pm
Any LNG silos pressurised to 0.6 bar placed in a near-vacuum?

Irrelevant.  The 0.6 bar is presumably gauge pressure, i.e. relative to the ambient (outside) pressure, and that's what matters.

However,

A dome by itself does not have a bottom; it is open.  It thus cannot contain any overpressure, by itself.  It needs to be connected to a "floor" to form a pressure vessel (with a gastight connection along the dome's entire perimeter, of course).  And the typical science fiction "domed city" at least seem to use the planetary surface directly as their bottom half.  That's where the problem comes: planetary surfaces don't have very high tensile strength.  E.g, a 50m diameter dome filled with an overpressure of 0.3 bar, will need an anchoring force of 37.5 kN for every decimeter of its perimeter, or the equivalent of the weight of 10 tonnes on Mars.  And this grows linearly with the diameter of the dome, so a 75m dome will need to be anchored by 56 kN/dm, and a 200m dome needs 150 kN/dm of anchoring.

The alternative is to build your own "floor" out of e.g. steel, and weld the dome to that, forming a pressure vessel.  But if that floor is flat all the way out to the perimeter, and form a sharp angle at the connection to the dome, you will need a very strong weld.  It is almost certainly easier and cheaper to make that connection rounded, just like you design any normal pressure vessel.

You can make most of the floor flat, especially if you weigh it down with a few meters of regolith or other heavy filling material on the inside (and you probably want that anyway for other reasons).  But the "corner" where it connects to the dome should be rounded.

You may end up with a structure that when viewed from the outside surface, looks like a dome, but that would be because you only see the dome part of the structure; in reality it would be a full pressure vessel, and be designed and shaped like one.

Pretty much this, as discussed many times through this thread. However, a stress relief groove will also help with the flat end of the pressure vessel. If you look at a Sodastream CO2 bottle, they use a multi-grooved flat end.

It just boils down to: how much do you want to fork out for a nice flat floor. Personally, I think they're overrated since you can roof over a crater and that will give you some radiation protection from the sloping crater walls (making the ground airtight/insulated being an exercise for the reader).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/13/2022 09:18 pm
Been fooling around with cylinders for most of the last year.

Seems more practical than domes to me.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/13/2022 09:39 pm
Mars by day and by night.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Paul451 on 02/14/2022 01:18 am
Pigeons? Unless they're being bred for food, I'd hope not.
Title: Re: Envisioning Amazing Martian Habitats
Post by: wannamoonbase on 02/14/2022 01:29 am
Been fooling around with cylinders for most of the last year.

Seems more practical than domes to me.


Certainly an above ground environment will be important.  I expect a lot of underground habitable space though.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/14/2022 01:59 am
Been fooling around with cylinders for most of the last year.

Seems more practical than domes to me.


Certainly an above ground environment will be important.  I expect a lot of underground habitable space though.
Most of the cylinders will be underground in whole or in part.  I like letting the ends poke out for little parks
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/14/2022 02:02 am
Pigeons? Unless they're being bred for food, I'd hope not.
Just a few, here and there... :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 02/14/2022 09:33 pm
If a park has a statue then there must be pigeons.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/14/2022 09:39 pm
If a park has a statue then there must be pigeons.
Forgot the statue, the pigeons got there first.  Who will deserve a statue for pigeons to rest on in a Martian city park?
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 02/14/2022 10:05 pm
Starman in Elon's roadster. I'm sure that someone will recover it one day. Great PR.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/14/2022 11:34 pm
Starman in Elon's roadster. I'm sure that someone will recover it one day. Great PR.
That's already in the history museum  ;D    (Image by Rémy Navarro)

Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 02/14/2022 11:43 pm
Nice. I hadn't seen that before.

Well that means we need another subject.  Mr Musk comes to mind.  Any others ???
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/15/2022 01:35 am
Nice. I hadn't seen that before.

Well that means we need another subject.  Mr Musk comes to mind.  Any others ???
Well, if things keep on as they are going now, perhaps mr. Jared Isaacman?
Or perhaps Ray Bradbury?  Is there a russian or chinese equivalent?

Title: Re: Envisioning Amazing Martian Habitats
Post by: Okie_Steve on 02/15/2022 01:38 am
How 'bout something fun from John Carter of Mars like a 4 armed Barsoom warrior?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/15/2022 01:47 am
How 'bout something fun from John Carter of Mars like a 4 armed Barsoom warrior?
Lot's of work there!  Unless I can find a commercial 3D model, then not hard at all :-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/15/2022 02:16 am
Spaceport with Surya in background.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/15/2022 02:39 am
Green Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: RonM on 02/15/2022 03:12 am
Pigeons? Unless they're being bred for food, I'd hope not.

Tesla robot pigeons. Maybe some robot squirrels too.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/15/2022 06:18 am
Maybe not pigeons, but it would be lovely with some songbirds. Very good for the mental health of the colonists.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/15/2022 07:06 am
Maybe not pigeons, but it would be lovely with some songbirds. Very good for the mental health of the colonists.

And to feed the cats (see the corner of the first of lamontagne's images).
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 02/15/2022 07:07 am
Pigeons? Unless they're being bred for food, I'd hope not.

Tesla robot pigeons. Maybe some robot squirrels too.

Maybe they could be little trash collectors.  Get a belly full and go to a dumping area and cough it up then start again.

Though, you would hope that rubbish lying around would not be an issue.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/22/2022 03:41 pm
Though, you would hope that rubbish lying around would not be an issue.

Surely human nature/society is on the cusp of finally being perfected....  all we need to do is adopt my preferred political ideology crest that next hill!  ;D



One of the best sci-fi twist endings is when the eugenics aliens in Babylon 5 praise the law-of-the-jungle "down below" (slums) as the only redeeming aspect of our spacefaring civilization.

We'd really need a separate thread, "Envisioning Depressing Martian Habitats." In the end, that would produce more accurate predictions of actual Mars architecture, methinks!  ???
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/25/2022 04:16 pm
Though, you would hope that rubbish lying around would not be an issue.

Surely human nature/society is on the cusp of finally being perfected....  all we need to do is adopt my preferred political ideology crest that next hill!  ;D



One of the best sci-fi twist endings is when the eugenics aliens in Babylon 5 praise the law-of-the-jungle "down below" (slums) as the only redeeming aspect of our spacefaring civilization.

We'd really need a separate thread, "Envisioning Depressing Martian Habitats." In the end, that would produce more accurate predictions of actual Mars architecture, methinks!  ???

Nah, aim high!!  As for depressing, just look at Ad Astra.  We can't do worse.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/25/2022 09:01 pm
Dystopian Martian Habitats is a thread we..... don't need...  :-)

Most people probably think tunnels habitats on Mars sound rather depressing. However, their main purpose is not to be *depressing*!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 01:15 am
It's probably cost effective to just keep the pressure membrane separate from the building.  Then you get space for trees and suchlike.  The glass is a little fanciful, but not all that much.
Title: Re: Envisioning Amazing Martian Habitats
Post by: DanClemmensen on 02/26/2022 01:49 am
Dystopian Martian Habitats is a thread we..... don't need...  :-)

Most people probably think tunnels habitats on Mars sound rather depressing. However, their main purpose is not to be *depressing*!
We don't need the dystopian thread because the topic has been extensively covered in Science Fiction. The current thread may be useful, because while Science Fiction has covered amazing habitats, many are not grounded in real science and engineering.
Title: Re: Envisioning Amazing Martian Habitats
Post by: GeneralHux on 02/26/2022 09:54 am
I wonder if it would be possible and practical to have these habitats mostly buried, but designed in such a way to still provide the same level of psychological comfort as a truly overground dome? Redesign the wonderful dome designs with an outdoor feeling to be under the regolith, but still retain that feeling?

The radiation exposure issue has been bothering me. I realize that it will probably be not even close to the greatest issue of a Martian habitat, but unlike the rest it seems that it doesn't have any evident solutions except for nearly impossible science fiction (terraforming), great reduction to human comfort (burying everyone in a hole), or outright ignoring it. Ignoring it may still pan out, as the there are still some level of uncertainty on the effects of prolonged exposure to low-level radiation, and the difficulty to evaluate those (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6149023/), and even the possibility that Martian settlers adjust to it as people in Ramsar may have (http://www.probeinternational.org/Ramsar.pdf).

However, it seems the coolest habitats here are the ones that are already ignoring it, which may still be too self-assured. And not so much that. Even if they work just fine for their potential dwellers, there is a sense that the first thing that one ought to attempt should be conservative in regards to safety.

So, can we have our cake and eat it too?


Can we use wide-spectrum artificial lighting that both provides the feeling of sunlight, and doubles as grow lights for underground plants that also works towards that comfort?

• Place a park on the open overground and exposed portion of the dome. A one-hour walk a day would be 10 mSv/a, which will be like average living in Ramsar, Iran. Even if we do 7 hour walk on Saturday, and a 7 hour trek in an EV suit on Sunday, that would still total to 30 mSv/a additional radiation.
• Place sleeping, living and working quarters in “buildings” on the underground portions of the dome, where the radiation is much lower.
• Fill the “outside”, between the buildings, with vegetation grown under strong warm artificial lights that give a sense of an outside to everyone working, cooking, eating, reading a book, etc.
• Non-pigeon birds living on the said “outside”. Probably no sparrows, too, much nicer than pigeons, but still we can do better.
• A lot of wetness outside, in levels not too much detrimental to living.

So much lightning might be expensive in terms of energy, but it won't add that much to the energy needed for heating, I hope, and may offset some of it directly.

(https://i.imgur.com/O9qAX20.png)

I do not think that one's comfort is dependant upon real and directly visible sky and so forth, some of the best places I can imagine living (that would include in the woods) may leave it totally invisible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/26/2022 02:01 pm
We'd really need a separate thread

Nah, aim high!!  As for depressing, just look at Ad Astra.  We can't do worse.

Dystopian Martian Habitats is a thread we..... don't need...  :-)

Most people probably think tunnels habitats on Mars sound rather depressing. However, their main purpose is not to be *depressing*!

As long as we're clear that in this thread our motivation is 100% toward creating sci-fi/fantasy art and sculpture (set in a fictional universe where "cost is no object"), and it has no relationship to actual architecture that will actually be built on Mars in the future, then I'm in full agreement.  :D

I'll be "amazed" if my rent on Mars is cheap. What I don't need/want is a bunch of useless non-utilized interior volume, which seems to be what passes for "amazing" in this thread.  :-\

All these designed might work for an Elysium-style city populated only by rich people, but that's all.

No real Mars city will resemble anything like anything in this thread. This is perfectly okay, of course! Keep going! However, let's not delude ourselves into thinking these architectures are anything but 100% fiction.



Someday in the distant future (or maybe not-so-distant), when someone designs buildings on Mars for real, they won't care about "aiming high" or "being amazing." They'll care about reducing cost. Perhaps someday (preferably before it's actually built!) people on NSF will work up the courage to discuss this reality.  :P

I get that this isn't the appropriate thread (and this will be my last post on the subject here) but it's disheartening to see what some members don't even want to have any discussion of it, in any thread, anywhere (see in bold). That's some real Emperor Has No Clothes thinking.

Anyway, back onto the topic of our amazing, fictional, "I Can't Believe It's Not Feasible!" architectures. ;D
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 03:28 pm
We'd really need a separate thread

Nah, aim high!!  As for depressing, just look at Ad Astra.  We can't do worse.

Dystopian Martian Habitats is a thread we..... don't need...  :-)

Most people probably think tunnels habitats on Mars sound rather depressing. However, their main purpose is not to be *depressing*!

As long as we're clear that in this thread our motivation is 100% toward creating sci-fi/fantasy art and sculpture (set in a fictional universe where "cost is no object"), and it has no relationship to actual architecture that will actually be built on Mars in the future, then I'm in full agreement.  :D

I'll be "amazed" if my rent on Mars is cheap. What I don't need/want is a bunch of useless non-utilized interior volume, which seems to be what passes for "amazing" in this thread.  :-\

All these designed might work for an Elysium-style city populated only by rich people, but that's all.

No real Mars city will resemble anything like anything in this thread. This is perfectly okay, of course! Keep going! However, let's not delude ourselves into thinking these architectures are anything but 100% fiction.



Someday in the distant future (or maybe not-so-distant), when someone designs buildings on Mars for real, they won't care about "aiming high" or "being amazing." They'll care about reducing cost. Perhaps someday (preferably before it's actually built!) people on NSF will work up the courage to discuss this reality.  :P

I get that this isn't the appropriate thread (and this will be my last post on the subject here) but it's disheartening to see what some members don't even want to have any discussion of it, in any thread, anywhere (see in bold). That's some real Emperor Has No Clothes thinking.

Anyway, back onto the topic of our amazing, fictional, "I Can't Believe It's Not Feasible!" architectures. ;D
So most people live in volume optimized spaces?  Parks do not exist and suburbs are a fiction?  Every square foot of a Macmansion is optimized and efficient? 
Mars will not be a mining town, the time for those is past.  Mars will be amazing, as suburbs are amazing by most measures of quality of life, or it will not be at all.
What exactly is wrong with the idea of large metal tubes with compact interior spaces as living habitats?  I'm willing to think the glass walls is not the most probable outcome, but it seems doable without too much energy requirements. 

The difference between Estepona, Spain, in the early 1900, when it was a dirt poor fishing village with a terrible conditions, and Estepona, Spain, in 2022, when it is a well off area with flowers in every street and color coder flower pots is linked to the efficiency of the production system, replacement of harsh working conditions with services, and social support systems.  Why should we not start on Mars with these directly?

Are flowers that expensive? ;-)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 03:36 pm
I wonder if it would be possible and practical to have these habitats mostly buried, but designed in such a way to still provide the same level of psychological comfort as a truly overground dome? Redesign the wonderful dome designs with an outdoor feeling to be under the regolith, but still retain that feeling?

The radiation exposure issue has been bothering me. I realize that it will probably be not even close to the greatest issue of

However, it seems the coolest habitats here are the ones that are already ignoring it, which may still be too self-assured. And not so much that. Even if they work just fine for their potential dwellers, there is a sense that the first thing that one ought to attempt should be conservative in regards to safety.

So, can we have our cake and eat it too?


Assuming you are talking about the images I have been posting, the tubes are actually designed with significant radiation protection in mind.  As you mention, most people do not spend significant hours in a park, every day.  This cutaway should show that what I am showing is simply a variation on what you illustrated in your cutaway.  The walls are 1m thick, the roof is a entire floor of solid concrete.  One of the sides is buried into an artificial hill, made from the regolith removed to create the tube's foundation.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 03:47 pm
The main structural principle that I try to illustrate with these wide spaces is that there is no economical gains in making tiny low radius pressure vessels on Mars.  The amount of material required is proportional to the volume.  1 000 000 m3 in 5m  diameter cylinders, that are tight and disagreeable, should have the same mass as 1 000 000 m3 in larger, more comfortable tubes with 40m in diameter.
The second principle here is that dingy corridor lighting is not going to be sustainable for humans.  Humans and plants are evolved for powerful lighting, with hundred of watts per m2.  We don't need powerful lights to sleep, work or survive, but we and plants do need them to prosper.  So even in an entirely underground base there will be some areas of very powerful light.  It would be deeply stupid not to have some of these areas shared by humans and plants, hence parks and public gardens.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/26/2022 03:55 pm
So most people live in volume optimized spaces?

Correct.

People buy a house that's a size they can afford. People do not buy houses by assuming an unconstrained size.

Parks do not exist

Indoor parks that are internally pressurized to 1 atmosphere do not exist, correct.

and suburbs are a fiction?

We can only dream! :D

  Every square foot of a Macmansion is optimized and efficient?

Again, if you're trying to design Elysium, taking inspiration from a McMansion is fine.

Mars will not be a mining town, the time for those is past.  Mars will be amazing, as suburbs are amazing by most measures of quality of life, or it will not be at all.

"Argument By Prophecy."

What exactly is wrong with the idea of large metal tubes with compact interior spaces as living habitats?

Nothing, but in most of the renderings I've seen here >75% of the usable interior volume is wasted.

  I'm willing to think the glass walls is not the most probable outcome, but it seems doable without too much energy requirements. 

Have we ever established a baseline for this "most probably outcome?" On this or any other thread?

If not, why not?

The difference between Estepona, Spain, in the early 1900, when it was a dirt poor fishing village with a terrible conditions, and Estepona, Spain, in 2022, when it is a well off area with flowers in every street and color coder flower pots is linked to the efficiency of the production system, replacement of harsh working conditions with services, and social support systems.  Why should we not start on Mars with these directly?

When the Wright Brothers were designing the first plane, why didn't they choose the shape of their aircraft by showing marketing sketches to a focus group of 1903 farmers?

Same here.

First, a design has to work (and that includes affordability). Everything else is secondary.

Are flowers that expensive? ;-)

Straw man. :-P
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 04:00 pm
The question of the second  generation (more average than the first), or the problems illustrated in the film 'Downsizing' (what happens when you lose your money in an Elysium) would be really interesting to explore, because they already are a problem here on Earth.  How to avoid a Brasilia and its slums on Mars.  Now that would really be amazing.  But probably is not the sole result of architecture and town planning, but will be affected by these. 
For example, what about a city build around entirely self driving cars and the equivalent of tunnels?
What happens if you energy source is extremely cheap and non polluting?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 04:02 pm
So most people live in volume optimized spaces?

Correct.

People buy a house that's a size they can afford. People do not buy houses by assuming an unconstrained size.

Parks do not exist

Indoor parks that are internally pressurized to 1 atmosphere do not exist, correct.

and suburbs are a fiction?

We can only dream! :D

  Every square foot of a Macmansion is optimized and efficient?

Again, if you're trying to design Elysium, taking inspiration from a McMansion is fine.

Mars will not be a mining town, the time for those is past.  Mars will be amazing, as suburbs are amazing by most measures of quality of life, or it will not be at all.

"Argument By Prophecy."

What exactly is wrong with the idea of large metal tubes with compact interior spaces as living habitats?

Nothing, but in most of the renderings I've seen here >75% of the usable interior volume is wasted.

  I'm willing to think the glass walls is not the most probable outcome, but it seems doable without too much energy requirements. 

Have we ever established a baseline for this "most probably outcome?" On this or any other thread?

If not, why not?

The difference between Estepona, Spain, in the early 1900, when it was a dirt poor fishing village with a terrible conditions, and Estepona, Spain, in 2022, when it is a well off area with flowers in every street and color coder flower pots is linked to the efficiency of the production system, replacement of harsh working conditions with services, and social support systems.  Why should we not start on Mars with these directly?

When the Wright Brothers were designing the first plane, why didn't they choose the shape of their aircraft by showing marketing sketches to a focus group of 1903 farmers?

Same here.

First, a design has to work (and that includes affordability). Everything else is secondary.

Are flowers that expensive? ;-)

Straw man. :-P
Damn, how can you do this so fast? ;-)
I'll think about it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/26/2022 04:16 pm
The main structural principle that I try to illustrate with these wide spaces is that there is no economical gains in making tiny low radius pressure vessels on Mars.  The amount of material required is proportional to the volume.

Exactly. There Ain't No Such Thing As Free Pressurized Volume, so every cubic inch is exploited to the maximum possible degree.

This is an argument for scale invariance. This isn't an argument for wasting interior volume.

The second principle here is that dingy corridor lighting is not going to be sustainable for humans.

So... adequate corridor lighting?  ;)

Humans and plants are evolved for powerful lighting, with hundred of watts per m2.  We don't need powerful lights to sleep, work or survive, but we and plants do need them to prosper.  So even in an entirely underground base there will be some areas of very powerful light.

Vertical farms, yeah. I expect people will visit these a lot during their off hours.

  It would be deeply stupid not to have some of these areas shared by humans and plants, hence parks and public gardens.

If we want to call the vertical farm areas "parks" or "public gardens," why not? Choosing a familiar name for psychological reasons doesn't cost or weigh anything.

Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 02/26/2022 04:27 pm
Damn, how can you do this so fast? ;-)

I'm very boring at parties, that's how. :-)

The "Depressing" line was tongue-in-cheek, but just trying to get creative juices flowing. Is it possible to make non-depressing places _without_ just throwing open volume & lots of exterior glass at the problem? Can the goal be accomplished more economically, somehow?

The optimization function is really more like "maximum happiness per dollar," not "maximum depressing-ness."


Chris-Craft (the high-end sailboat maker) and luxury RV designers (Monaco, Tiffin, etc) probably have the most experience in this area. Amazing how much living space they can "tetris" into a small volume.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 07:05 pm
Damn, how can you do this so fast? ;-)

I'm very boring at parties, that's how. :-)

The "Depressing" line was tongue-in-cheek, but just trying to get creative juices flowing. Is it possible to make non-depressing places _without_ just throwing open volume & lots of exterior glass at the problem? Can the goal be accomplished more economically, somehow?

The optimization function is really more like "maximum happiness per dollar," not "maximum depressing-ness."


Chris-Craft (the high-end sailboat maker) and luxury RV designers (Monaco, Tiffin, etc) probably have the most experience in this area. Amazing how much living space they can "tetris" into a small volume.
A boat loses a foot in length everyday you are in it.... and almost everybody that owns a RV also owns a stabile home. 
I'm more worried about how the function of a district changes with time, as population ages and needs change.

I absolutely agree the very first habitats on Mars will be mass/volume optimized. Perhaps later versions might be energy or work optimized? And that depends on technology and what can be made on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 07:32 pm
Although I highlight the 40m module to the left in the images, and the parks as the amazing spaces, I expect there will be a large number of smaller modules like the one to the right.

If you allow for a space used for foot circulation at 'ground' level, separate from the vehicle circulation level bellow, and if the space to cultivate flowers and small vegetable can be included in this, then the 'wasted' space is perhaps 20-30% in the large buildings. The smaller 18m cylinders are much more optimized.

This is basically Edinburgh New Town; the larger homes with gardens, that are still used by families and the well to do, and the much smaller coach houses, that were used as stables and for horse maintenance but are now converted for students and less well off people.  Upper and lower floors for servants are now technical areas.  The many small cooperative homes for workers, a great innovation at the time, would also correspond to the 18m tubes.
I guess it would be more optimum to move my heavy roof entirely outside, and have the right hand part of the luxury homes entirely under rock.  My idea was that the mass of the radiation shield would collapse the tubes in case of pressure failure, and that the loss in efficiency was worth the gain in safety.
Very debatable, of course.
I freely admit that the glass is a luxury item that is not needed for the primary focus of space occupation.  I think however that many Martian citizens might be interested in the investment. 

I guess that you might also have a certain number of totally enclosed tubes as  form of low rent districts?  But I would hope that we have learned from the post second world war decades that this is perhaps not a good idea?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/26/2022 10:05 pm
Illustrated here are two fabrication methods for the large 40m tubes.  BTW these are the children of 18m tubes, that are the children of 9m tubes, that are... Spaceship.

Anyway in the foreground is a tunneling machine, that cuts a ditch and assembles the tubes as it goes along.  Every now and then it pinches the tubes off like a sausage and stars a new one.
In the background, a shipyard like area builds entire large tubes, that are moved about using multiple self propelled modular transporters, as are Starships today.

Which one would work best?  Do the ideas make any sense?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Okie_Steve on 02/26/2022 11:50 pm
Pressurizing makes things harder but lower gravity makes them easier. For comparison, naturally occurring lava tubes on Earth max out at a diameter of maybe 100 meters while on Mars they might reach 100 times larger - multiple kilometers wide/high. So large structures might be easier to support from a structural point of view than might be assumed based on Earthly experience.

https://www.universetoday.com/147360/lava-tubes-on-the-moon-and-mars-are-really-really-big-big-enough-to-fit-an-entire-planetary-base/

Edit - Not trying to sidetrack to a discussion of lava tube habitats, just pointing out that Mars architecture will be literally other worldly.  ::)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/26/2022 11:57 pm
Seems some billionaires think it is OK to live in windowless dorms...

https://www.theguardian.com/artanddesign/2021/nov/04/torture-experiment-architects-appalled-windowless-student-megadorm

Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 02/27/2022 01:31 am
So most people live in volume optimized spaces?

Correct.

People buy a house that's a size they can afford. People do not buy houses by assuming an unconstrained size.

Parks do not exist

Indoor parks that are internally pressurized to 1 atmosphere do not exist, correct.

and suburbs are a fiction?

We can only dream! :D

  Every square foot of a Macmansion is optimized and efficient?

Again, if you're trying to design Elysium, taking inspiration from a McMansion is fine.

Mars will not be a mining town, the time for those is past.  Mars will be amazing, as suburbs are amazing by most measures of quality of life, or it will not be at all.

"Argument By Prophecy."

What exactly is wrong with the idea of large metal tubes with compact interior spaces as living habitats?

Nothing, but in most of the renderings I've seen here >75% of the usable interior volume is wasted.

  I'm willing to think the glass walls is not the most probable outcome, but it seems doable without too much energy requirements. 

Have we ever established a baseline for this "most probably outcome?" On this or any other thread?

If not, why not?

The difference between Estepona, Spain, in the early 1900, when it was a dirt poor fishing village with a terrible conditions, and Estepona, Spain, in 2022, when it is a well off area with flowers in every street and color coder flower pots is linked to the efficiency of the production system, replacement of harsh working conditions with services, and social support systems.  Why should we not start on Mars with these directly?

When the Wright Brothers were designing the first plane, why didn't they choose the shape of their aircraft by showing marketing sketches to a focus group of 1903 farmers?

Same here.

First, a design has to work (and that includes affordability). Everything else is secondary.

Are flowers that expensive? ;-)

Straw man. :-P
Why does Starship have a large useless common area up front?  (Nevermind the practicality of the mega window)

It may not be the final design, but it's certainly not fantasy, and it shows what SpaceX engineers think about free spaces.

As for suburbs, you made a funny joke, but didn't address the point - they are very inefficient and people love them.

Some people think they're too crowded and prefer even more rural.

Mars will be very autonomous. The locals will want free spaces, and they'll make them.

It's human nature.  It took SpaceX how long before they had a restaurant and then a rooftop bar?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/27/2022 01:29 pm
You will not get 1 million people paying to move to Mars to live in a windowless barracks and eat spoo.

There's your reason.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 02/27/2022 01:33 pm
Illustrated here are two fabrication methods for the large 40m tubes.  BTW these are the children of 18m tubes, that are the children of 9m tubes, that are... Spaceship.

Anyway in the foreground is a tunneling machine, that cuts a ditch and assembles the tubes as it goes along.  Every now and then it pinches the tubes off like a sausage and stars a new one.
In the background, a shipyard like area builds entire large tubes, that are moved about using multiple self propelled modular transporters, as are Starships today.

Which one would work best?  Do the ideas make any sense?

The hard part is the endcap. If you simply join the cylinders up in say a hexagon, octagon, N-gon, then you avoid that problematic curved structure. You don't have to do it, but the bonus is that a circular-ish space has the advantage of it being possible to walk in a loop.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/28/2022 12:24 am
10 class grade school and Basketball court.

This is the difference between a settlement and a base.  It strange that we don't yet know if it is possible.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/28/2022 12:30 am
Illustrated here are two fabrication methods for the large 40m tubes.  BTW these are the children of 18m tubes, that are the children of 9m tubes, that are... Spaceship.

Anyway in the foreground is a tunneling machine, that cuts a ditch and assembles the tubes as it goes along.  Every now and then it pinches the tubes off like a sausage and stars a new one.
In the background, a shipyard like area builds entire large tubes, that are moved about using multiple self propelled modular transporters, as are Starships today.

Which one would work best?  Do the ideas make any sense?

The hard part is the endcap. If you simply join the cylinders up in say a hexagon, octagon, N-gon, then you avoid that problematic curved structure. You don't have to do it, but the bonus is that a circular-ish space has the advantage of it being possible to walk in a loop.
It's possible, and we though about it when we designed them.  But we ended up asking what is the maximum size of a module regarding accidents, fires, etc?  The 200m long x 40m diameter module houses about 300 people in luxury mode, perhaps up to 1000+ in sardine in a can mode.  We felt that was large enough in case of evacuation due to fire of depressurization.
The parks are larger, but in most cases will have much lower population.
So the ends are, in a sense, fire or depressurization breaks.  This is seats of the pants design though, another group might have settled for another number.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/28/2022 01:01 pm
Added ceramic on the lower wall, and sound absorbing panels on the upper wall.
Works for subway stations so should work here as well?

A wide blind stainless steel wall is not nicer than a wide concrete blind wall, after all.
Added extra artificial lighting as well.  Flattens the shadows and brightens up everything a bit.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 02/28/2022 01:24 pm
Though, you would hope that rubbish lying around would not be an issue.

Surely human nature/society is on the cusp of finally being perfected....  all we need to do is adopt my preferred political ideology crest that next hill!  ;D



One of the best sci-fi twist endings is when the eugenics aliens in Babylon 5 praise the law-of-the-jungle "down below" (slums) as the only redeeming aspect of our spacefaring civilization.

We'd really need a separate thread, "Envisioning Depressing Martian Habitats." In the end, that would produce more accurate predictions of actual Mars architecture, methinks!  ???
Disagree that it’s more realistic. Windows, stuff like that are going to happen or there won’t be people living there at all.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 02/28/2022 05:07 pm
We'd really need a separate thread

Nah, aim high!!  As for depressing, just look at Ad Astra.  We can't do worse.

Dystopian Martian Habitats is a thread we..... don't need...  :-)

Most people probably think tunnels habitats on Mars sound rather depressing. However, their main purpose is not to be *depressing*!

As long as we're clear that in this thread our motivation is 100% toward creating sci-fi/fantasy art and sculpture (set in a fictional universe where "cost is no object"), and it has no relationship to actual architecture that will actually be built on Mars in the future, then I'm in full agreement.  :D

I'll be "amazed" if my rent on Mars is cheap. What I don't need/want is a bunch of useless non-utilized interior volume, which seems to be what passes for "amazing" in this thread.  :-\

All these designed might work for an Elysium-style city populated only by rich people, but that's all.

No real Mars city will resemble anything like anything in this thread. This is perfectly okay, of course! Keep going! However, let's not delude ourselves into thinking these architectures are anything but 100% fiction.



Someday in the distant future (or maybe not-so-distant), when someone designs buildings on Mars for real, they won't care about "aiming high" or "being amazing." They'll care about reducing cost. Perhaps someday (preferably before it's actually built!) people on NSF will work up the courage to discuss this reality.  :P

I get that this isn't the appropriate thread (and this will be my last post on the subject here) but it's disheartening to see what some members don't even want to have any discussion of it, in any thread, anywhere (see in bold). That's some real Emperor Has No Clothes thinking.

Anyway, back onto the topic of our amazing, fictional, "I Can't Believe It's Not Feasible!" architectures. ;D

Congrats on so eloquently expressing your disdain for the ideas in this thread, which is, as the title indicates, dedicated to "envisioning amazing Martian habitats". I wonder why you have posted so much in here given what you really think about the subject.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/28/2022 06:22 pm
Here is an image of how windows might be fitted in.
The thin metal wall plate, 6mm, is replaced with much thicker beams that have a similar cross section around the windows.  There is no effort transmitted through the windows, they only need to resist atmospheric pressure.

The angular beams are probably not at the optimum angle, that I think should be the one of COPVs winding.   The glass can be quite thick, probably some kind of multilayer composite, with an air gap.  This arrangement has been explored before on another thread, (Domes on Mars?) but it's fun to detail it here for the big tubular habitats.

The idea here is not to try for enough light to grow food with the settlement.  Thick multilayer glass will have a high shading coefficient.  It's mainly an esthetic and psychological purpose that is served.
The basic module is 2m x 2m.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/28/2022 09:23 pm
The main structural principle that I try to illustrate with these wide spaces is that there is no economical gains in making tiny low radius pressure vessels on Mars.  The amount of material required is proportional to the volume.

Exactly. There Ain't No Such Thing As Free Pressurized Volume, so every cubic inch is exploited to the maximum possible degree.

This is an argument for scale invariance. This isn't an argument for wasting interior volume.

The second principle here is that dingy corridor lighting is not going to be sustainable for humans.

So... adequate corridor lighting?  ;)

Humans and plants are evolved for powerful lighting, with hundred of watts per m2.  We don't need powerful lights to sleep, work or survive, but we and plants do need them to prosper.  So even in an entirely underground base there will be some areas of very powerful light.

Vertical farms, yeah. I expect people will visit these a lot during their off hours.

  It would be deeply stupid not to have some of these areas shared by humans and plants, hence parks and public gardens.

If we want to call the vertical farm areas "parks" or "public gardens," why not? Choosing a familiar name for psychological reasons doesn't cost or weigh anything.
When I say powerful lighting I don't mean vertical farms.  Just the equivalent of a nice sunny day.  Vertical farms are horrible places to visit, plant production optimized light is not human optimized light.  A typical corridor is 50-100 lux, while a nice sunny day is something like 10 000 lux, while a vertical farm is 50 000 lux or more.

You won't be running after a soccer ball in a vertical farm  :)  while you would expect to do this in a park.  Or putter about in a vertical farm, as compared to a middling efficiency but highly satisfying allotment.  There will be older people eventually.  Or kids that don't grow up to be as smart and motivated as their immigrant parents.  And children that need to go outside for the sanity of their parents.   

This is all in the idea that you would want to live your life on Mars, and raise a family, in opposition to working on Mars for a while. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 02/28/2022 09:39 pm
I guess that if we roll back this thread to the very first post, about flat packed habitats and such, the emphasis should be on compact and economical constructions, without much ISRU beyond piled up sand.  In such a case, a Starship on the side with the big window poking out seems like a pretty amazing possibility. A cargo Starship with no window is less glorious and amazing, but for working people, a few cameras and screes would probably be enough of a look out for a few years.

This will never house more than a few hundred people though.  So yes, they would be amazing in a sense, but what comes after seems more interesting and amazing.  What the first hundreds/thousands will be working on, rather than what the first hundreds will be living in. And that's what I proposed 158 pages ago  ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/03/2022 06:24 pm
Damn, how can you do this so fast? ;-)

I'm very boring at parties, that's how. :-)

The "Depressing" line was tongue-in-cheek, but just trying to get creative juices flowing. Is it possible to make non-depressing places _without_ just throwing open volume & lots of exterior glass at the problem? Can the goal be accomplished more economically, somehow?

The optimization function is really more like "maximum happiness per dollar," not "maximum depressing-ness."


Chris-Craft (the high-end sailboat maker) and luxury RV designers (Monaco, Tiffin, etc) probably have the most experience in this area. Amazing how much living space they can "tetris" into a small volume.
A boat loses a foot in length everyday you are in it.... and almost everybody that owns a RV also owns a stabile home. 
I'm more worried about how the function of a district changes with time, as population ages and needs change.

I guess we're losing perspective, and forgetting that RVs and boats have much larger space allocated to living than is used in human spaceflight?

On the ISS your "bedroom" is literally a closet. What I'm proposing is cavernous in comparison.

If you're scoffing at living in an RV, you're not the one who's going to Mars. Sorry, them's the breaks. There's a hundred (hardier) humans in line behind you, eager to be Mars colonists in spite of the compact living space.

I absolutely agree the very first habitats on Mars will be mass/volume optimized. Perhaps later versions might be energy or work optimized? And that depends on technology and what can be made on Mars.

The first version will be mass, volume, energy, and work optimized. These each have a relative cost, and that total cost will be minimized.

This is what "whole system design" means.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/03/2022 06:29 pm
[snip]
Why does Starship have a large useless common area up front?  (Nevermind the practicality of the mega window)

It may not be the final design, but it's certainly not fantasy, and it shows what SpaceX engineers think about free spaces.

"Useless" is your own insertion.

I expect this large common volume will be used as a cafeteria and/or gymnasium for most of the time. Almost all the rest of the pressurized volume will be densely packed with small private "pods," maximizing volumetric utilization.

As for suburbs, you made a funny joke, but didn't address the point - they are very inefficient and people love them.

They love them (in part) because they're relatively cheap. This is not true on Mars.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/03/2022 06:30 pm
You will not get 1 million people paying to move to Mars to live in a windowless barracks and eat spoo.

There's your reason.

So do you think this is a Marketing thread, or an Engineering thread?

If it's the former, let's not fool ourselves that it's the latter.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/03/2022 06:32 pm
Though, you would hope that rubbish lying around would not be an issue.

Surely human nature/society is on the cusp of finally being perfected....  all we need to do is adopt my preferred political ideology crest that next hill!  ;D



One of the best sci-fi twist endings is when the eugenics aliens in Babylon 5 praise the law-of-the-jungle "down below" (slums) as the only redeeming aspect of our spacefaring civilization.

We'd really need a separate thread, "Envisioning Depressing Martian Habitats." In the end, that would produce more accurate predictions of actual Mars architecture, methinks!  ???
Disagree that it’s more realistic. Windows, stuff like that are going to happen or there won’t be people living there at all.

"Argument by Prophecy" again.  :-\
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/03/2022 06:36 pm
[snip]

Congrats on so eloquently expressing your disdain for the ideas in this thread, which is, as the title indicates, dedicated to "envisioning amazing Martian habitats". I wonder why you have posted so much in here given what you really think about the subject.

While we're all "wondering," I wonder if there was supposed to be a point somewhere in this post.  ::)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/03/2022 06:39 pm
The main structural principle that I try to illustrate with these wide spaces is that there is no economical gains in making tiny low radius pressure vessels on Mars.  The amount of material required is proportional to the volume.

Exactly. There Ain't No Such Thing As Free Pressurized Volume, so every cubic inch is exploited to the maximum possible degree.

This is an argument for scale invariance. This isn't an argument for wasting interior volume.

The second principle here is that dingy corridor lighting is not going to be sustainable for humans.

So... adequate corridor lighting?  ;)

Humans and plants are evolved for powerful lighting, with hundred of watts per m2.  We don't need powerful lights to sleep, work or survive, but we and plants do need them to prosper.  So even in an entirely underground base there will be some areas of very powerful light.

Vertical farms, yeah. I expect people will visit these a lot during their off hours.

  It would be deeply stupid not to have some of these areas shared by humans and plants, hence parks and public gardens.

If we want to call the vertical farm areas "parks" or "public gardens," why not? Choosing a familiar name for psychological reasons doesn't cost or weigh anything.
When I say powerful lighting I don't mean vertical farms.  Just the equivalent of a nice sunny day.  Vertical farms are horrible places to visit, plant production optimized light is not human optimized light.  A typical corridor is 50-100 lux, while a nice sunny day is something like 10 000 lux, while a vertical farm is 50 000 lux or more.

Ooh, I know this one!  :D

So you put an 80% shade cloth (presumably reflecting back onto the plants) over the shelves, and now your vertical farm doubles as your "nice sunny day."

You're welcome!  8)

(as for the spectrum, I presume you'll have a system with little wearable tags that automatically switches on the green lights for inspection, so your joggers can just wear one of those)


You won't be running after a soccer ball in a vertical farm  :)

Nope. They'll invent new, Martian games.

That's why they'll be different from us. Better adapted.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/03/2022 06:54 pm
[snip]
Why does Starship have a large useless common area up front?  (Nevermind the practicality of the mega window)

It may not be the final design, but it's certainly not fantasy, and it shows what SpaceX engineers think about free spaces.

"Useless" is your own insertion.

I expect this large common volume will be used as a cafeteria and/or gymnasium for most of the time. Almost all the rest of the pressurized volume will be densely packed with small private "pods," maximizing volumetric utilization.

As for suburbs, you made a funny joke, but didn't address the point - they are very inefficient and people love them.

They love them (in part) because they're relatively cheap. This is not true on Mars.
I was being facetious.

You were arguing how nobody will leave room for parks and recreation because they're not "optimal use of space."

I showed you that the only group that's designing habitats for real use found it necessary to include a large amount of such "non optimal" space, even in a transient habitat such as a ship.

I also pointed out that you never really addressed the popularity of suburbs other than by cracking a joke at them - but they are suboptimal and people do like them.  Most people would rather have an "unnecessarily" large house than an apartment in an optimal high rise.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/03/2022 06:59 pm
I showed you that [the Starship common area is] "non optimal" space

No you didn't. You're assuming that based on your own interpretation of preliminary artistic renderings.

I also pointed out that you never really addressed the popularity of suburbs other than by cracking a joke at them - but they are suboptimal and people do like them.  Most people would rather have an "unnecessarily" large house than an apartment in an optimal high rise.

It's popular on Earth because it's cheap. It's not cheap on Mars, so your analogy breaks down.

Is that sufficiently addressed yet?
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/03/2022 07:31 pm
I showed you that [the Starship common area is] "non optimal" space

No you didn't. You're assuming that based on your own interpretation of preliminary artistic renderings.

I also pointed out that you never really addressed the popularity of suburbs other than by cracking a joke at them - but they are suboptimal and people do like them.  Most people would rather have an "unnecessarily" large house than an apartment in an optimal high rise.

It's popular on Earth because it's cheap. It's not cheap on Mars, so your analogy breaks down.

Is that sufficiently addressed yet?
My interpretation that the dome is a recreational area is not exactly controversial...  Amd those "renderings" are by the team designing the thing, for real - not just opining on them.

Even if it changes later, if shows you what that team considers as important. Obviously that common area costs mass and volume.

And if they're willing to entertain it on a ship, they're much more likely to want it on a permanent, planet-side, habitat.


And no, suburbs are expensive.  People pay for houses that are literally 10x what they actually need. Housing is their #1 expense. And yet they choose to pay more than the minimum necessary.

You're not arguing with me, you're arguing with the human population.  Even in places where space is tight..  entire floors of high rise buildings are dedicated to common areas...  Parks are put in even when real estate pricing is super high.

The guys telling you Mars town will have parks - they're not being radical or extreme architects, they're just looking out their windows.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/03/2022 07:54 pm

Ooh, I know this one!  :D

So you put an 80% shade cloth (presumably reflecting back onto the plants) over the shelves, and now your vertical farm doubles as your "nice sunny day."

You're welcome!  8)

(as for the spectrum, I presume you'll have a system with little wearable tags that automatically switches on the green lights for inspection, so your joggers can just wear one of those)


You won't be running after a soccer ball in a vertical farm  :)

Nope. They'll invent new, Martian games.

That's why they'll be different from us. Better adaptation.
I've visited grow rooms.  They have a fun level of 0. It's just as fun as visiting an automated warehouse.  They are not for humans, they are for plants.  I'm certain trees and grass are 'happy' in parks, but the parks are really made for people.
You will not stroll through grow rooms and enjoy the view ;-)

I think the cost of the pressure envelope is way lower than the cost of the finished buildings and that extending the envelope is not that expensive, compared to any number of other costs. 

I don't think, but I may be wrong, that there is an amazing compact habitat without greenery about it, designed for a lifelong occupation.  I guess they would already exist on Earth, if they were possible.  The best analog I know is the Raglan mine in Northern Canada.  Where the environment is pretty bad, you don't go out during most of the winter, but you can get away after a few weeks.  People do live in the villages up there, but it's not fun either.  Productivity is not high, to say the least. Humans have adapter to the far North, but it's not a top population center.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/03/2022 07:57 pm
What is the land value of Central park, New York?  How come it exists?
Hyde park?
Mont Royal?
etc...

And yes, there are more pictures of Central Park that of low cost apartments in Brooklyn.  If such a thing exists ;-)

I suddenly remember a really cheap rental in a basement in Brooklyn a few years ago, with my wife and son (shudder).  Even there, you could find parks just around the corner.
Title: Re: Envisioning Amazing Martian Habitats
Post by: daavery on 03/03/2022 08:12 pm
so start with how much are you willing to pay for open space ? $1000/M^3 , $10,000/M^3, $100,000/M^3. cost will certainly determine how much open space there is. I expect for a fair number of years mars occupied space will cost in the $10,000/M^3 range or higher
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 03/03/2022 08:41 pm
At first, sure. But it might eventually be cheaper than cities on Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/03/2022 08:56 pm
so start with how much are you willing to pay for open space ? $1000/M^3 , $10,000/M^3, $100,000/M^3. cost will certainly determine how much open space there is. I expect for a fair number of years mars occupied space will cost in the $10,000/M^3 range or higher
Open area m3 will be less expensive than built up m3.  In the same way the m3 over your front yard are much less expensive than the m3 of your house.  The ratio for this is less high than on Earth, because of the cost of the pressurized envelope.

For what it's worth, our basic cost results for the habitats.  this is materials.  I expect most of the labor and detailed work, electricity, plumbing and such would go the the building areas, an not the envelope.  My very rough guess is that the pressure envelope is at the most 5-10% of the costs.

Twark_Main's proposition is that this is a fallacy and that there will be no 'front yard' space.  I disagree.  Respectfully.

The team's web site : https://sites.google.com/view/foundationcitystate/accueil
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/03/2022 09:01 pm
so start with how much are you willing to pay for open space ? $1000/M^3 , $10,000/M^3, $100,000/M^3. cost will certainly determine how much open space there is. I expect for a fair number of years mars occupied space will cost in the $10,000/M^3 range or higher
Absolutely.  As in situ resources come on line and power gets cheaper, the construction cost go down fast.  The first habitats will quickly become 'quaint' and 'cramped' compared to what later Martians build.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 04:18 am
Public and private spaces

With the cost of a house reaching 1,3 million dollars in Toronto, but the actual construction cost of the building being just a fraction of that, I guess people are willing to pay one million dollars to get a garden.  Mars should be in that price range.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/04/2022 12:58 pm
I showed you that [the Starship common area is] "non optimal" space

No you didn't. You're assuming that based on your own interpretation of preliminary artistic renderings.

I also pointed out that you never really addressed the popularity of suburbs other than by cracking a joke at them - but they are suboptimal and people do like them.  Most people would rather have an "unnecessarily" large house than an apartment in an optimal high rise.

It's popular on Earth because it's cheap. It's not cheap on Mars, so your analogy breaks down.

Is that sufficiently addressed yet?
My interpretation that the dome is a recreational area is not exactly controversial...  Amd those "renderings" are by the team designing the thing, for real - not just opining on them.

Even if it changes later, if shows you what that team considers as important. Obviously that common area costs mass and volume.

And if they're willing to entertain it on a ship, they're much more likely to want it on a permanent, planet-side, habitat.


And no, suburbs are expensive.  People pay for houses that are literally 10x what they actually need. Housing is their #1 expense. And yet they choose to pay more than the minimum necessary.

You're not arguing with me, you're arguing with the human population.  Even in places where space is tight..  entire floors of high rise buildings are dedicated to common areas...  Parks are put in even when real estate pricing is super high.

The guys telling you Mars town will have parks - they're not being radical or extreme architects, they're just looking out their windows.

so start with how much are you willing to pay for open space ? $1000/M^3 , $10,000/M^3, $100,000/M^3. cost will certainly determine how much open space there is. I expect for a fair number of years mars occupied space will cost in the $10,000/M^3 range or higher
Open area m3 will be less expensive than built up m3.  In the same way the m3 over your front yard are much less expensive than the m3 of your house.  The ratio for this is less high than on Earth, because of the cost of the pressurized envelope.

For what it's worth, our basic cost results for the habitats.  this is materials.  I expect most of the labor and detailed work, electricity, plumbing and such would go the the building areas, an not the envelope.  My very rough guess is that the pressure envelope is at the most 5-10% of the costs.

Twark_Main's proposition is that this is a fallacy and that there will be no 'front yard' space.  I disagree.  Respectfully.

The team's web site : https://sites.google.com/view/foundationcitystate/accueil

And, to a point, pressurised volume gets cheaper per m^3 the larger you get, the square-cube law working in your favour, just make the walls thicker.

Looking at your sausage hab design, the steel ribs would be the perfect place to put maybe tankage for 20-50cm of water shielding. Either on the inside where they can act as thermal ballast too, or on the exterior as ice. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 01:34 pm

And, to a point, pressurised volume gets cheaper per m^3 the larger you get, the square-cube law working in your favour, just make the walls thicker.

Looking at your sausage hab design, the steel ribs would be the perfect place to put maybe tankage for 20-50cm of water shielding. Either on the inside where they can act as thermal ballast too, or on the exterior as ice.
Makes sense. I think the insulation should be on the outside, with the air tight wall acting as the vapor barrier.  In such a case, the radiation protection water would be inside the insulation and therefore liquid.  It would add a significant radiation reduction factor to the public spaces.  I guess a clever designer would find a way of turning those water volumes into structural elements, possible reducing the risk of collapse in the case of accidental pressure loss.

BTW during the night, I expect there might be insulated shades that are drawn down over the windows.  I think those would have to be exterior.  Something of a maintenance chore.  To validate there would have to be a heat balance done on the habitat in summer and winter / night and day conditions.  A nice modeling job to do for a happy volunteer...  ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 01:36 pm
The facades as shown are awfully monotonous though. Contradicts some of the tenets of modern town design, as far as I gather from the one book I read on the subject!

I've found the best answer to this in Germany, where many people have these tiny rock gardens and flower pots in the front of their houses in the tight village streets.  Now, not everyone approves of pink flamingoes and suchlike but it does give you something to look at!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 01:41 pm
Or perhaps I should just offset the living units and break up those lines a bit?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 03:23 pm
I showed you that [the Starship common area is] "non optimal" space

No you didn't. You're assuming that based on your own interpretation of preliminary artistic renderings.

I also pointed out that you never really addressed the popularity of suburbs other than by cracking a joke at them - but they are suboptimal and people do like them.  Most people would rather have an "unnecessarily" large house than an apartment in an optimal high rise.

It's popular on Earth because it's cheap. It's not cheap on Mars, so your analogy breaks down.

Is that sufficiently addressed yet?
My interpretation that the dome is a recreational area is not exactly controversial...

"Argument by Popularity"  :-\

Amd those "renderings" are by the team designing the thing, for real - not just opining on them.

Even if it changes later, if shows you what that team considers as important. Obviously that common area costs mass and volume.

"Common areas" are different from "useless" space. I am objecting to the latter, not the former.

And no, suburbs are expensive.

Not like on Mars, it ain't!

You're not arguing with me, you're arguing with the human population.  Even in places where space is tight..  entire floors of high rise buildings are dedicated to common areas...  Parks are put in even when real estate pricing is super high.

The guys telling you Mars town will have parks - they're not being radical or extreme architects, they're just looking out their windows.

Again, I'm not objecting to common areas. That's a straw man. I'm objecting to useless areas, or otherwise extremely poor utilization of (extremely expensive) pressurized volume.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/04/2022 03:43 pm
I showed you that [the Starship common area is] "non optimal" space

No you didn't. You're assuming that based on your own interpretation of preliminary artistic renderings.

I also pointed out that you never really addressed the popularity of suburbs other than by cracking a joke at them - but they are suboptimal and people do like them.  Most people would rather have an "unnecessarily" large house than an apartment in an optimal high rise.

It's popular on Earth because it's cheap. It's not cheap on Mars, so your analogy breaks down.

Is that sufficiently addressed yet?
My interpretation that the dome is a recreational area is not exactly controversial...

"Argument by Popularity"  :-\

Amd those "renderings" are by the team designing the thing, for real - not just opining on them.

Even if it changes later, if shows you what that team considers as important. Obviously that common area costs mass and volume.

"Common areas" are different from "useless" space. I am objecting to the latter, not the former.

And no, suburbs are expensive.

Not like on Mars, it ain't!

You're not arguing with me, you're arguing with the human population.  Even in places where space is tight..  entire floors of high rise buildings are dedicated to common areas...  Parks are put in even when real estate pricing is super high.

The guys telling you Mars town will have parks - they're not being radical or extreme architects, they're just looking out their windows.

Again, I'm not objecting to common areas. That's a straw man. I'm objecting to useless areas, or otherwise extremely poor utilization of (extremely expensive) pressurized volume.
The one-liner jokes are funny, but not convincing.

"Argument by popularity" is misapplied here, since the very topic is the social evolution of habitats.

Read above, your definition of "useless" is fluid.  Let's sharpen it.  You were arguing for an exclusively efficiency-driven design.  Yiu didn't argue against "extremely inefficient" spaces, you argued against any inefficiency.

By your standards, the front portion of Starship is a non-starter, and you indeed argued that it is merely "preliminary renderings".

While it may be so, it does communicate the intent and priorities of the designers of Starship, and by extension, the Mars habitats.

Space on a Starship is even more expensive, and the benefit of open spaces is lower since it's only transient, used by the occupants for a limited time.

Just those two factors should indicate that they intend to build inefficient, recreational, useless open spaces as part of the habitat.

It's human nature.  Nobody wants to live in coffins.

Your dedication to efficiency is similar a little bit to the consternation over F9's wasteful use of propellant on RTLS and why can't we just use SMART since it's so much more efficient.

Which it is, but only in the micro-view. Once Musk pulled up and looked at the whole system, he realized that overall one-piece reuse is more advantageous.

Same will happen here.  Your super efficient colony will get more people per $, but it won't get people...  And the entire goal here is growth, and growth is driven by popularity, since you can't have economics without people.




Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 03:45 pm


Again, I'm not objecting to common areas. That's a straw man. I'm objecting to useless areas, or otherwise extremely poor utilization of (extremely expensive) pressurized volume.
I think we need to know your definition of useless space, because otherwise we are talking past one another.

Is a personal garden a useless space?  Or is it the space over this garden by, let's say, 3-4m useless space?
Are all the volumes over open common areas higher than , say, 4m useless spaces?
If the empty space is used to more air about and equalize temperatures, is it still a useless space? Can it become a very large air duct that happens to have trees and plants in it?
Is a green park with trees a useless space?

Although this list rather looks like one of those tiresome leading questions arguments, supposed to lead to a HAHA counterargument, they really are separate questions,  they just happen to be on similar subjects.

What might be the reasonable portion of common areas in a city plan on Mars?  And what is a common area?

Do the large vistas illustrated look better and would be more 'comfortable' than smaller, shorter line of sight areas?  Or is it just an illusion based on our lack of familiarity with anything else?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 03:51 pm
Can an argument be made that vast open areas add inertia to the system, and therefore have a use or even provide some measure of safety? 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 04:51 pm

Ooh, I know this one!  :D

So you put an 80% shade cloth (presumably reflecting back onto the plants) over the shelves, and now your vertical farm doubles as your "nice sunny day."

You're welcome!  8)

(as for the spectrum, I presume you'll have a system with little wearable tags that automatically switches on the green lights for inspection, so your joggers can just wear one of those)


You won't be running after a soccer ball in a vertical farm  :)

Nope. They'll invent new, Martian games.

That's why they'll be different from us. Better adaptation.
I've visited grow rooms.  They have a fun level of 0. It's just as fun as visiting an automated warehouse.  They are not for humans, they are for plants.  I'm certain trees and grass are 'happy' in parks, but the parks are really made for people.
You will not stroll through grow rooms and enjoy the view ;-)

So fix that.

Making a grow room pleasant will take vastly less cost/mass/labor/energy than adding an entirely new pressurized area.

Reality check: on the ISS they cancelled the "bedroom" module, so astronauts just sleep in the laboratory.

I think the cost of the pressure envelope is way lower than the cost of the finished buildings and that extending the envelope is not that expensive, compared to any number of other costs. 

Based on...


I don't think, but I may be wrong, that there is an amazing compact habitat without greenery about it, designed for a lifelong occupation.  I guess they would already exist on Earth, if they were possible.  The best analog I know is the Raglan mine in Northern Canada.  Where the environment is pretty bad, you don't go out during most of the winter, but you can get away after a few weeks.  People do live in the villages up there, but it's not fun either.  Productivity is not high, to say the least. Humans have adapter to the far North, but it's not a top population center.

I agree that adding lots of greenery (by contrast with adding big empty unused space and oversized windows) is one of the cheapest and best ways to improve happiness and create "amazing" living spaces.


I've noticed a bias here (common to the "McMansion" worldview) to view large featureless voids as "roomy" and sub-divided spaces as "cramped." But I (and most traditional folk architectures) find just the opposite to be true: a large empty void space feels very small indeed, but it "grows larger" as it's divided up into (functional, well-designed) space.

Anyone who's planted a garden knows how much "roomier" the outside feels vs. the previous lawn. Adding stuff (if done in the correct way) will actually make the space grow, not shrink.


Divide space. Not too much. Mostly, plants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 05:24 pm
What is the land value of Central park, New York?  How come it exists?

Because the elites wanted a park which just-so-happened to kick out the poor free black people and poor irish people who lived there at the time (of which Seneca Village was only the most famous example).

https://en.wikipedia.org/wiki/Central_Park#History

https://www.centralparknyc.org/articles/seneca-village

Don't ask a question if you don't want to know the answer.

Hyde park?

Literally owned by royalty.

Mont Royal?

Wealthy Monrealers living next-door were upset that (gasp) working-class people were going to move in and ruin their view of trees, so they persuaded the government to buy out a bunch of "private lots." The perspective of those private landowners (aka history's "losers") is lost to history, of course.

https://www.lemontroyal.qc.ca/en/history-of-mount-royal


So far we're 3-for-3 on the Elysium trope here.  :-\

I suddenly remember a really cheap rental in a basement in Brooklyn a few years ago, with my wife and son (shudder).

You'll never hear me say that cheap modern architecture is good.

  Even there, you could find parks just around the corner.

Sure, but how do we design non-miserable buildings (ie better buildings than your old apartment) in an economic environment where it's suddenly not the cheapest option to just "throw a park at it?"

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 05:49 pm
What is the land value of Central park, New York?  How come it exists?

Because the elites wanted a park which just-so-happened to kick out the poor free black people and poor irish people who lived there at the time (of which Seneca Village was only the most famous example).

https://en.wikipedia.org/wiki/Central_Park#History

https://www.centralparknyc.org/articles/seneca-village

Don't ask a question if you don't want to know the answer.

Hyde park?

Literally owned by royalty.

Mont Royal?

Wealthy Monrealers living next-door were upset that (gasp) working-class people were going to move in and ruin their view of trees, so they persuaded the government to buy out a bunch of "private lots." The perspective of those private landowners (aka history's "losers") is lost to history, of course.

https://www.lemontroyal.qc.ca/en/history-of-mount-royal


So far we're 3-for-3 on the Elysium trope here.  :-\

I suddenly remember a really cheap rental in a basement in Brooklyn a few years ago, with my wife and son (shudder).

You'll never hear me say that cheap modern architecture is good.

  Even there, you could find parks just around the corner.

Sure, but how do you design non-miserable buildings (ie better buildings than your old apartment) in an economic environment where it's suddenly not the cheapest option to just "throw a park at it."
I always want to know the answer, that's why I take the risk of asking questions.
There won't be any Elysium on Mars?  That's likely. 

The city of Montreal bought the land for Mont Royal Park.  rich Montreal moved out of the city for the summer when they could, and the lived on Westmount, that already has good views, thank you very much.  There are always more than one reason for things.  The park was also a plan t reduce worker mortality rates. 
So at best 2.5.  anyway I'm certain you know that parks were part of a wider philosophy of what cities were for, and I'm not taking you up on this as it doesn't address the main issue for me, i.e what exactly is wasted space in the illustration I'm proposing here?

And you didn't answer the question about the value of Central Park, just about its history.

The value of the shell is based on the value of its materials compared to the value of materials of a built up occupied space. If your French is OK, I can send the spreadsheet.  There is a small extract I translated in one of the posts.
It's also based on the logical premise that a shell is just a shell, while a building is a whole system than is way more expensive than just the shell.

This is so much work.  Can't you take a cooperative stance and just show me what I could be better?  I'm getting exhausted here, and so much energy lost.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 05:59 pm
[snip]
The one-liner jokes are funny, but not convincing.

"Argument by popularity" is misapplied here, since the very topic is the social evolution of habitats.

This rebuttal makes no sense.

Your subjective interpretation of an old SpaceX rendering as showing "useless" space is a popular ("not exactly controversial") interpretation of that old SpaceX rendering. That is what you said.

But now you're revising history, as if you said that "useless" space is popular.

These are two very different things, obviously. I was replying to the former.

Read above, your definition of "useless" is fluid.  Let's sharpen it.  You were arguing for an exclusively efficiency-driven design.  Yiu didn't argue against "extremely inefficient" spaces, you argued against any inefficiency.

Then you have misinterpreted my argument.

If you would kindly point out what specific words I said that made you think that, I'll edit it to be more clear. Thanks!



By your standards, the front portion of Starship is a non-starter, and you indeed argued that it is merely "preliminary renderings".

While it may be so, it does communicate the intent and priorities of the designers of Starship, and by extension, the Mars habitats.

I disagree with your assumption (yes, assumption) that it is "useless" space, especially in micro-gravity. So this entire line of reasoning is specious.

Again, I'm not arguing against common space. I'm arguing against big empty spaces for the sake of "wow, look at that big empty space."


It's human nature.  Nobody wants to live in coffins.

"Coffins" is a pretty extreme (in the absurd) interpretation of what I'm advocating for, don't you think?

Can we not straw-man my argument, for once?

RVs and sailboats (my previously stated examples) aren't coffins, obviously.

Your dedication to efficiency is similar a little bit to the consternation over F9's wasteful use of propellant on RTLS and why can't we just use SMART since it's so much more efficient.

Which it is, but only in the micro-view. Once Musk pulled up and looked at the whole system, he realized that overall one-piece reuse is more advantageous.

I would *love* if there was some actual whole-system design (ala F9) in this thread!!  ;D ;D

This is, in fact, exactly what I'm advocating for. Everyone else seems to be more interested in producing marketing brochures.

"How do you provide happiness at the lowest total systems cost?"

Same will happen here.  Your super efficient colony will get more people per $, but it won't get people...  And the entire goal here is growth, and growth is driven by popularity, since you can't have economics without people.

I don't want to maximize unhappiness. I don't want to minimize cost, at the cost of happiness.

I want to maximize happiness per dollar. Provide happiness, but be smart about it.

How can I get this (simple fact) through to people???
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 03/04/2022 06:07 pm
The pressure drop rate has a direct linear relationship between the volume of the atmospheric mass and the size of the hole. A 2 cm hole in the ISS 500 m^3 would have the same pressure drop rate as a 1 m diameter hole in a 1.25M m^3 volume. A 1.25M m^3 volume is 107m x 107m x 107m. It is a large area but not supper sized. Basically a large window blow out would not be a catastrophic event but one that was an immediate emergency needing a quick response to limit atmosphere loss.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 06:13 pm
Can an argument be made that vast open areas add inertia to the system, and therefore have a use or even provide some measure of safety?

Large buffers of atmospheric gas would be best stored as cryogenic liquid, escaping the pressure vessel scaling TANSTAAFL.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 06:32 pm

I don't want to maximize unhappiness. I don't want to minimize cost, at the cost of happiness.

I want to maximize happiness per dollar. Provide happiness, but be smart about it.

How can I get this (simple fact) through to people???
Probably because you are just using words to describe your intent, without describing what the result might look/be like?

For example, I'm a not particularly clever person, who obstinately makes images of buildings in tubes as a hobby.  I also have the intent of showing habitats that maximize happiness for minimal cost.  but as I have a limited tool set, it only goes so far.  There is little point in criticizing what I do if the criticism doesn't also include proposals for improvement, references or suggestions.
'Can do better' is ok, I guess, but I already know that.  I would much rather have : 'how about this', or 'have you thought of that'.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 06:36 pm
Can an argument be made that vast open areas add inertia to the system, and therefore have a use or even provide some measure of safety?

Large buffers of atmospheric gas would be best stored as cryogenic liquid, escaping the pressure vessel scaling TANSTAAFL.
I was rather disappointed with that when I tried it.  The volume of the tanks was surprisingly large.  But I was talking more a  thermal buffer, and/or as a dilution system for organic volatiles or CO2.  Although I guess thick concrete walls are probably all that is needed as a thermal buffer anyway.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/04/2022 06:43 pm
The pressure drop rate has a direct linear relationship between the volume of the atmospheric mass and the size of the hole. A 2 cm hole in the ISS 500 m^3 would have the same pressure drop rate as a 1 m diameter hole in a 1.25M m^3 volume. A 1.25M m^3 volume is 107m x 107m x 107m. It is a large area but not supper sized. Basically a large window blow out would not be a catastrophic event but one that was an immediate emergency needing a quick response to limit atmosphere loss.
I guess that might be a point in favor of a large buffer volume.  I think it also speak as to what might be a reasonable sized safe volume in regards to the potential risks.  also suggests that if you absolutely want windows, it's probably a smart move to subdivide them.
The refrigeration code, for example, has a ratio of smallest occupied volume to refrigerant quantity to prevent suffocation.  I guess it might make sense to work out a calculation where you take the largest likely hole, calculate the required evacuation time to a safe area, and fix the required volume.  Or the other way around, design the volume and fix the largest individual window pane area allowed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/04/2022 06:54 pm
The issue is the use of open space volume versus subdivision of the same volume into smaller habitats and work spaces. This subject will probably be taken up many times as Musk City grows from one to one million. The two principal stakeholders, financiers of various living spaces and Mars citizens, would probably have a major say in how development takes place and how living volume is utilized.

My first thought is that citizens would want more open space and financiers would want more profitable workspaces. On second thought, it could be the citizens who might want  more rooms and workplaces so that the city could grow to a self-sustaining size more quickly. Mars pioneers have drunk the Musk cool-aid!  :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/04/2022 07:08 pm
The biggest proponents of Mars open spaces and volumes might be the Mars Architects who want to realize their own dreams!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/04/2022 09:05 pm
The facades as shown are awfully monotonous though. Contradicts some of the tenets of modern town design, as far as I gather from the one book I read on the subject!

I've found the best answer to this in Germany, where many people have these tiny rock gardens and flower pots in the front of their houses in the tight village streets.  Now, not everyone approves of pink flamingoes and suchlike but it does give you something to look at!

Indeed breaking up the facades makes for much more human and livable architecture.

The picture shows Sluseholmen (The Sluice Island) in Copenhagen. It was formerly occupied by a big factory. Now the plot has been intersected by several canals. Each of the resulting islands is now occupied by a squarish apartement block, with a communal garden in the middle and underground parking below.

As you can see it is not really visible that each apartment block is in fact one big building. That's because every staircase has been given a different facade. Not just different colouring but varying design and height. It gives a really nice feel to the whole place (I come there often). Also, it fits very well with the historical architecture in the Copenhagen harbour area, such as you see in Christianshavn.

By the way, the little red wooden sheds/shacks down by the harbour front, where the boats are, are the only remnants from the days of the factory. They were originally nailed together by the factory workers for their hobby projects and boat clubs. The housing architects insisted on keeping those ramshackle sheds because they give a lot of ambiance to the new housing area.

I also think that goes for Mars. There will be improvised slapdash architecture inside the living spaces and it may very well turn out to be the most popular communal areas of the colony. Settlers always want a bar (saloon!) area....   

Finally, regarding Copenhagen harbour. In the days of hreavy industries the water used to be very polluted. Now it is clean and great for swimming. In the picture there are two floating "harbour baths": walkway and sun deck constructions floating on the water.   
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 11:21 pm

I don't want to maximize unhappiness. I don't want to minimize cost, at the cost of happiness.

I want to maximize happiness per dollar. Provide happiness, but be smart about it.

How can I get this (simple fact) through to people???
Probably because you are just using words to describe your intent, without describing what the result might look/be like?

My exclusive use of human English words is entirely a personal failure of mine. Trust me, it's better this way. I have no artistic abilities to speak of.  :-\

For example, I'm a not particularly clever person, who obstinately makes images of buildings in tubes as a hobby.  I also have the intent of showing habitats that maximize happiness for minimal cost.  but as I have a limited tool set, it only goes so far.  There is little point in criticizing what I do if the criticism doesn't also include proposals for improvement, references or suggestions.
'Can do better' is ok, I guess, but I already know that.  I would much rather have : 'how about this', or 'have you thought of that'.

Sorry, but a fully-formed design didn't spring out of my head like the cranium of Jove.   :-[

We don't know what a volume-efficient design looks like. None of us do. That's the problem.

Rather than write a gigantic boring treatise on interior design, I'll just point you in the direction of the best one ever written: A Pattern Language (http://google.com/search?q=A+Pattern+Language+1977). PDFs are available, but I highly recommend buying or borrowing a hard-copy.




Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 11:23 pm
Can an argument be made that vast open areas add inertia to the system, and therefore have a use or even provide some measure of safety?

Large buffers of atmospheric gas would be best stored as cryogenic liquid, escaping the pressure vessel scaling TANSTAAFL.
I was rather disappointed with that when I tried it.  The volume of the tanks was surprisingly large.

We should be comparing this against pressurized gas bottles, correct?

  But I was talking more a  thermal buffer, and/or as a dilution system for organic volatiles or CO2.  Although I guess thick concrete walls are probably all that is needed as a thermal buffer anyway.

Yeah, agreed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/04/2022 11:42 pm
If you're a fan of thinking in pictures, Google Image search Earthships, and Hong Kong apartments interiors, and mash the two together. That will get you pretty close to what Mars living is liable to actually look like (again, as distinct from the "marketing brochure for soft comfortable middle-class Americans" version of Mars).

Now before you glance at Google Image Search, latch onto some visual detail you disapprove of, and treat it as if my entire proposal hinges on that little detail, just don't. There's a lot of things in those images that I don't like, either. Treat them as an interior design problem to be solved (AKA design constraints). Don't treat them as potential straw-man "rebuttals" to be lazily grasped for, weaponized to silence the heretic (yours truly), and then forgotten (along with the underlying design lessons) just as quickly.

Is that too much to ask? Can we all behave?

Probably not, but I'm doing it anyway as a favor to the "visual learners" in the thread. No good deed goes unpunished! :D
Title: Re: Envisioning Amazing Martian Habitats
Post by: TripD on 03/05/2022 12:28 am
There is a lot going on in this thread.  But, in keeping with the spirit of doing much with little, an image occurred to me.  A connecting tube about the width of a street, at an arbitrary incline with horizontal offshoots that afford enclaves for housing or shops.  I thought of looking up a small street in San Francisco.  The mere act of tilting one's head upward lent itself to a feeling of a grander scale than was there.  The interfaces of horizontal tubes with the inclined tube would allow for unique designs for transition.  Like stoops in a neighborhood.


Is building connections off of an incline the simplest or most efficient. Heck no. But perhaps there might be other reasons that it would be required.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/05/2022 12:35 am
If you're a fan of thinking in pictures, Google Image search Earthships, and Hong Kong apartments interiors, and mash the two together. That will get you pretty close to what Mars living is liable to actually look like (again, as distinct from the "marketing brochure for soft comfortable middle-class Americans" version of Mars).

Now before you glance at Google Image Search, latch onto some visual detail you disapprove of, and treat it as if my entire proposal hinges on that little detail, just don't. There's a lot of things in those images that I don't like, either. Treat them as an interior design problem to be solved (AKA design constraints). Don't treat them as potential straw-man "rebuttals" to be lazily grasped for, weaponized to silence the heretic (me), and then forgotten (along with the underlying design lessons) just as quickly.

Is that too much to ask? Can we all behave?

Probably not, but I'm doing it anyway as a favor to the "visual learners" in the thread. No good deed goes unpunished! :D
I rather like those.  Pain in the fundamentals to model in 3D though.  So mushy.
Won't they turn into Gaudi's Casa Mila, at scale?  You're asking a lot of poor little me.

Anyway I think the colored facades and displacements of the units has made for a much more interesting arrangement.  Much more interesting to walk the second image, I feel.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/05/2022 12:57 am
After reading the Wikipedia article on Earthships, I don't see much difference with what I'm doing as far as the main buildings go.  Scale perhaps.  Energy, garbage, sewage, shelter, clean water and food.  Got them all.  Recycled materials may not be possible at first, but I expect the first habitats will be recycled with time.

I have separated the pressure envelope function from the building function.   It's not a function found on Earth anyway.  But I feel it is essential to be able to have trees and gardens near the homes.
I guess my external insulation using vacuum insulation is also more technological.  Perhaps I can justify this because of the -68C temperatures.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/05/2022 06:19 am
Can an argument be made that vast open areas add inertia to the system, and therefore have a use or even provide some measure of safety?

Larger volumes are inherently more safe because they lose pressure more slowly, as oldAtlasEguy showed. Meteoroid impacts are mostly a non-issue for Mars but something like a crashing cargo drone could be a consideration.

At 30m height, you start to get micro-climates forming. By putting the sausages on a slope you might get quite a bit of circulation within them. That is an advantage for TripD's arrangement. Also, a slight slope would increase illumination into the sausages. Running north-south you could angle the windows to the sun, effectively corrugating the tube, but achieve >50% daylighting. More glass and steel ould be needed but it also reduces stresses.

Also, at very large sizes (eg 200m diameter domes) pressurised volumes start to add a significant amount of radiation shielding from air mass, which works out to ~12g/cm^2 for every 100m of sea level air thickness.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/05/2022 12:25 pm
After reading the Wikipedia article on Earthships, I don't see much difference with what I'm doing as far as the main buildings go.  Scale perhaps.  Energy, garbage, sewage, shelter, clean water and food.  Got them all.  Recycled materials may not be possible at first, but I expect the first habitats will be recycled with time.

I have separated the pressure envelope function from the building function.   It's not a function found on Earth anyway.  But I feel it is essential to be able to have trees and gardens near the homes.
I guess my external insulation using vacuum insulation is also more technological.  Perhaps I can justify this because of the -68C temperatures.
When constructing a large volume vessel to contain living space, you will need many acrylic or glass panes with metal frames to contain the pressure. In addition to the transparent windows, the frames could also help brighten the indoor environment if they were composed of highly reflective stainless steel, such as 304, 304L, 316, or 316L.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/05/2022 01:15 pm
After reading the Wikipedia article on Earthships, I don't see much difference with what I'm doing as far as the main buildings go.  Scale perhaps.  Energy, garbage, sewage, shelter, clean water and food.  Got them all.  Recycled materials may not be possible at first, but I expect the first habitats will be recycled with time.

I have separated the pressure envelope function from the building function.   It's not a function found on Earth anyway.  But I feel it is essential to be able to have trees and gardens near the homes.
I guess my external insulation using vacuum insulation is also more technological.  Perhaps I can justify this because of the -68C temperatures.
When constructing a large volume vessel to contain living space, you will need many acrylic or glass panes with metal frames to contain the pressure. In addition to the transparent windows, the frames could also help brighten the indoor environment if they were composed of highly reflective stainless steel, such as 304, 304L, 316, or 316L.
I'd love to use stainless steel.  I do worry that chromium may be rare on Mars, and that the nickel based stainless steels may be much harder to use.  The 300 series are almost 20% chrome, for example.
The recent illustrations are all with stainless steel materials, but it's hard to control what the software I use for illustration proposes as a surface vs what might really be the look of the stainless.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/05/2022 01:33 pm
Safety is an interesting issue, and mirrors the endless debates about Starship safety and escape capsules.
I think the avenue of determining risks for each space is interesting.  As on Earth, point of safety and distance might be the basic principle.  As on Earth as well, intervention by the Mars equivalent of a fire brigade might need to be baked into the designs to avoid overdesign.  On Earth codes are very focused on fires, then Earthquakes and then then, perhaps wind and water and Energy.  On Mars codes will need to include depressurization as a new risk, increase the effects of smoke and allowances for them, no rain, no wind simplifies things, and have some basic radiation protection values.  I guess solar storms are also a new risk.
As on Earth these will not be absolutes, but will incorporate risk management elements and try to strike a balance between performance and prescriptions.

A hospital, where patients are not mobile, would have more pressure safeties than a housing module, where people can escape, that would have more than a Park, where there a fewer people.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/05/2022 02:32 pm
I've always loved this series of images by the French comic book artist Moebius.
As it was done in 1978 I can't help thinking that it was an utopian ideal that he envisioned for the post second world was developments in French cities low cost housing developments.  Now in 2022, the hoped for evolution hasn't happened, as far as I can see.
I think it's food for though regarding Martian cities, and perhaps we could find a way to go straight to image 6.  As long as we believe image 6 is better than image 1.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 03/05/2022 03:21 pm
How to process air of a large habitats >100,000 m^3 volume.

By using a version of the same atmospheric components extraction equipment being used by the propellant production. An industrial scale processor can be built that would reduce an atmospheric processing into its components: Water, LCO2, LOX, LN2 as well as other items in more trace amounts but as atmospheric processing is at a high volume these trace elements build up and can be removed as well. Then from these components plus some additions of O2 and N2 reconstituting atmosphere in very clean form. The CO2 can be sent over to the farm area to enrich the farm atmosphere with high levels of CO2. The farm atmosphere is also processed to reconstitute to the components and because it would have increased O2 levels That excess O2 would then be used provide the O2 for the Human habitat areas. Also the needed replacement due to losses would be just CO2 an N2 condensed out of the Mars atmosphere. Plants are the method to convert that C02 into O2 for use in the Human habitat area. N2 is needed by plants and they will absorb it out of the atmosphere.

The key here is that by using a cryogenic condensation separation process down to pure components can biologically sterilize and remove toxins as well from the habitat atmosphere very efficiently. Only water has to be filtered and treated. The only drawback is that this processing uses a lot of energy but there are some pluses to if the system is well designed such that the heat being produced for cooling is used to heat the cryo components back up to normal temp before return to the habitat.

Such things as CO2 absorbents is delegated to emergency shelters and not used in normal almost closed loop processing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/06/2022 03:11 pm
A more detailed cut way view of a tubular habitat:

This is a third generation habitat, perhaps 40-50 years after the first utilitarian tubes of the first pioneers.

The upper areas have the apartments (4 floors) and a public walkway that links up with all the other habitats.  To the right, the private 'surface' space, for gardens and play areas.

The first basement holds the self driving pods circulation paths and a number of small gardens with artificial lighting.
Under that, a first floor of hydroponics and aeroponics for smaller plants such as lettuce, strawberries, etc. In the midddle area, storage lockers
Below, a larger hydroponics set-up for larger plants, plus the pressurized refuges interspaced with machinery, such a water and air treatment units.
At the bottom, a pipe and cable tray utilidor.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 03/06/2022 04:44 pm
I believe you will need to divide the tube 50/50 between the human areas and the farm, storage/supplies, and utilities area. That is from the 1970's colonies studies about the amount of volume of farm area to human are as at least 1/3 of farm area to 2/3 all other areas. So putting the floor and the submerging of 50% of the tube at or below ground level with the other half above ground level. This would give the farm output to have an excess but not by much output to create a stored supply in case of farm failure events. Unlike the Colony close to Earth that help is only a week away. Mars help from Earth is months away at best and could be more than a year. To have separated and excess supply producing farms is a safety implementation. If the supply of the stored starts to be close to overflowing the excess could be exported to other space exploratory missions and bases undercutting cost of supplies from other sources like Earth.

Such tubes as described in the post above could each house thousands of inhabitants. 100 such could cause the "city" or colony to be as much as 1M inhabitants. Just 10 could be 100K. Each tube would be semi-independent of the others such that a catastrophic event on one tube would be handled just by shifting the population to the others. The larger the total numbers of tubes the better the accommodation for such catastrophic events.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/06/2022 06:08 pm
I believe you will need to divide the tube 50/50 between the human areas and the farm, storage/supplies, and utilities area. That is from the 1970's colonies studies about the amount of volume of farm area to human are as at least 1/3 of farm area to 2/3 all other areas. So putting the floor and the submerging of 50% of the tube at or below ground level with the other half above ground level. This would give the farm output to have an excess but not by much output to create a stored supply in case of farm failure events. Unlike the Colony close to Earth that help is only a week away. Mars help from Earth is months away at best and could be more than a year. To have separated and excess supply producing farms is a safety implementation. If the supply of the stored starts to be close to overflowing the excess could be exported to other space exploratory missions and bases undercutting cost of supplies from other sources like Earth.

Such tubes as described in the post above could each house thousands of inhabitants. 100 such could cause the "city" or colony to be as much as 1M inhabitants. Just 10 could be 100K. Each tube would be semi-independent of the others such that a catastrophic event on one tube would be handled just by shifting the population to the others. The larger the total numbers of tubes the better the accommodation for such catastrophic events.
Yes, the settlement is pretty much as you describe it.  We do have some surface greenhouses planned, as we speculated glass might improve in the future (after all, foldable glass screens!) and orbital mirrors could be used to improve illumination locally. 
Our tubes are a little smaller at 300 inhabitants per tube, but the principle is the same.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 03/06/2022 09:08 pm
Those tubes will only maintain their shape by air pressure, is that correct?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/06/2022 09:27 pm
Those tubes will only maintain their shape by air pressure, is that correct?
Yes, they are too thin to take any load without the internal pressure.  I expect they could stand up to their own dead weight once they are in place,  with the buried part serving to anchor the walls.  The interior floors and structures are mostly self standing, with the loads going to the two central walls that in turn transmit them to the ground.  There is a layer of insulation between the metal and the ground, to spread the load and protect the metal from surface defects.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/07/2022 01:29 am
Those tubes will only maintain their shape by air pressure, is that correct?
Yes, they are too thin to take any load without the internal pressure.  I expect they could stand up to their own dead weight once they are in place,  with the buried part serving to anchor the walls.  The interior floors and structures are mostly self standing, with the loads going to the two central walls that in turn transmit them to the ground.  There is a layer of insulation between the metal and the ground, to spread the load and protect the metal from surface defects.
Good plan. Could also use a thicker steel sheeting on the vessel below ground, to protect against those ground surface defects.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/07/2022 01:44 am
You have a nice rendering for a stage III Martian settlement employing large pressure vessels.

Back at Stage I initial landings, a similar pattern of smaller vessels could be laid out using steel pressure vessels already on hand, namely, the Starships themselves.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/07/2022 02:21 am
In reply 3224, Lamontagne has shown us some of the architectural possibilities of employing large pressure vessels with habitats and open spaces inside.

Back at Stage I, a similar engineering approach could be adopted. We could subdivide a 9m pressurized tube into rectangular living and working spaces, by employing metal trusses and vertical columns as shown in Lamontagne's renderings.

In stage I we may still not know the exact effects of GCR on the human body. A cautious  approach would limit the size and extent of windows in each vessel and instead, plan to mostly bury them under 3m of regolith to protect against radiation and occasional micrometeorites.

Edited spelling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/07/2022 02:59 pm
In reply 3224, Lamontagne has shown us some of the architectural possibilities of employing large pressure vessels with habitats and open spaces inside.

Back at Stage I, a similar engineering approach could be adopted. We could subdivide a 9m pressurized tube into rectangular living and working spaces, by employing metal trusses and vertical columns as shown in Lamontagne's renderings.

In stage I we may still not know the exact effects of GCR on the human body. A cautious  approach would limit the size and extent of windows in each vessel and instead, plan to mostly bury them under 3m of regolith to protect against radiation and occasional micrometeorites.

Edited spelling.
Like this moon base proposal?  would work on Mars as well, I expect?
I would tend to dig out a hole to lower the average height and have the exit and entry at 'ground' level, but this works as well, I guess.
P.S paper in the links.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/07/2022 08:02 pm
In reply 3224, Lamontagne has shown us some of the architectural possibilities of employing large pressure vessels with habitats and open spaces inside.

Back at Stage I, a similar engineering approach could be adopted. We could subdivide a 9m pressurized tube into rectangular living and working spaces, by employing metal trusses and vertical columns as shown in Lamontagne's renderings.

In stage I we may still not know the exact effects of GCR on the human body. A cautious  approach would limit the size and extent of windows in each vessel and instead, plan to mostly bury them under 3m of regolith to protect against radiation and occasional micrometeorites.

Edited spelling.
Like this moon base proposal?  would work on Mars as well, I expect?
I would tend to dig out a hole to lower the average height and have the exit and entry at 'ground' level, but this works as well, I guess.
P.S paper in the links.
Yes, this paper gives  the general idea. Also agree with your variation.

It amuses me that 21 authors from public institutions were required to produce this paper. We know it only takes two determined authors and a handful of reviewers from NASAspaceflight to produce a major paper that addresses the use of BFR (Starship) on another world.

Edited spelling.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Okie_Steve on 03/07/2022 08:18 pm
Something I do worry about with closed system habitats is how to deal with slow long term build up of toxins. Both human sourced like heavy metals and Mars local like perchlorate. Old Atlas_Eguy suggested liquifying air to remove impurities which sounds like a valid approach for dealing with traces of things like radon and carbon monoxide which are apparently bad news for long term exposure.

Something similar will be needed for water to deal with miscible "forever" chemicals like trichloroethane that are causing trouble in groundwater here.

I expect interiors surfaces will need to be periodically cleaned by some sort of robot to remove biofilms that may form due to things like shed skin cells, bacteria, mold, algae etc, life being opportunistic about filling such niches. So "cleanability" may be an architectural consideration.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/07/2022 08:45 pm
Something I do worry about with closed system habitats is how to deal with slow long term build up of toxins. Both human sourced like heavy metals and Mars local like perchlorate. Old Atlas_Eguy suggested liquifying air to remove impurities which sounds like a valid approach for dealing with traces of things like radon and carbon monoxide which are apparently bad news for long term exposure.

Something similar will be needed for water to deal with miscible "forever" chemicals like trichloroethane that are causing trouble in groundwater here.


I expect interiors surfaces will need to be periodically cleaned by some sort of robot to remove biofilms that may form due to things like shed skin cells, bacteria, mold, algae etc, life being opportunistic about filling such niches. So "cleanability" may be an architectural consideration.
Good question
This complex problem is addressed in the ISS by a series of physical and chemical removal systems. It is good engineering problem for another thread.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Okie_Steve on 03/08/2022 12:37 pm
Something I do worry about with closed system habitats is how to deal with slow long term build up of toxins. Both human sourced like heavy metals and Mars local like perchlorate. Old Atlas_Eguy suggested liquifying air to remove impurities which sounds like a valid approach for dealing with traces of things like radon and carbon monoxide which are apparently bad news for long term exposure.

Something similar will be needed for water to deal with miscible "forever" chemicals like trichloroethane that are causing trouble in groundwater here.


I expect interiors surfaces will need to be periodically cleaned by some sort of robot to remove biofilms that may form due to things like shed skin cells, bacteria, mold, algae etc, life being opportunistic about filling such niches. So "cleanability" may be an architectural consideration.
Good question
This complex problem is addressed in the ISS by a series of physical and chemical removal systems. It is good engineering problem for another thread.

Yes, the environmental processing will be mostly out of sight. For this thread I just wanted to touch on the possible architectural impact needed for things like effective air circulation and surface cleaning.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/08/2022 01:26 pm
Something I do worry about with closed system habitats is how to deal with slow long term build up of toxins. Both human sourced like heavy metals and Mars local like perchlorate. Old Atlas_Eguy suggested liquifying air to remove impurities which sounds like a valid approach for dealing with traces of things like radon and carbon monoxide which are apparently bad news for long term exposure.

Something similar will be needed for water to deal with miscible "forever" chemicals like trichloroethane that are causing trouble in groundwater here.


I expect interiors surfaces will need to be periodically cleaned by some sort of robot to remove biofilms that may form due to things like shed skin cells, bacteria, mold, algae etc, life being opportunistic about filling such niches. So "cleanability" may be an architectural consideration.
Good question
This complex problem is addressed in the ISS by a series of physical and chemical removal systems. It is good engineering problem for another thread.

Yes, the environmental processing will be mostly out of sight. For this thread I just wanted to touch on the possible architectural impact needed for things like effective air circulation and surface cleaning.
For fire protection, we should plan for sprinklers everywhere, including any large open areas.  The areas should be subdivided so deluge systems could be used for these large areas, as is done in aircraft hangars, for example.  The same system could be used to create localized rain, that can be used for cleaning and for watering plants.  If the large habitats are installed with a 1-2 degree slope they will drain by gravity.  Large water tanks are a given anyway for many reasons.  Fire protection reservoirs are already a feature of all Earth cities.
Reverse osmosis membrane separation is already used for soil remedial operation of contamination by perchlorates.
It requires a lot of clean water though, so there would have to be an external source of clean water.
So a typical habitat might have a sanitary waste water treatment system, and a 'rain water' treatment system.  Plenty of water will be required for irrigation anyway, so might as well use it for general cleaning first.

As each human produces, among other things, about 3 kg of skin flakes per year, that works out to about one tonne of dust for a 300 person habitat, per year.  Plus all the hair and many times more than that for the  plants debris over the year.  All eventual food for a bacteria based water treatment system or compost generation units.

It's a common, and conservative, metric to use 10 l/s per person of fresh air.  So that means 3000 l/s for a 300 person habitat, or about 6000 cfm.  That is not a very large piece of equipment.  Would be some kind of CO2 scrubber, as well as capturing composite organic volatiles such as methane.  Air handling equipment for temperature control and general ventilation might take the form of large fans, or perhaps a convective cycle using heat and cold, if than can be applied.  Depends a bit on the scale of things.  There would have to be some kind of condensation apparatus that remove excess humidity, in particular if lots of plants are present in the common areas.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/08/2022 01:36 pm
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
The habitats I illustrate have gaps between the metal skin and the interior concrete, where crawler robots, analogous to the existing duct cleaning robots of today, can be sent periodically to check for cracks and corrosion, for example.   Like todays plumbing cameras and roto routers  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: sebk on 03/08/2022 01:56 pm
Fire protection (mostly firefighting but also fire prevention) could be aided by having control of the atmosphere.

For example in normal pressure (101kPa) atmosphere lowering oxygen content to 16% is well tolerated by people but makes common materials like wood and paper non-flammable. You rather don't want to have it that way permanently as it likely reduces physical performance of people, but in case of fire emergency you can shift atmosphere contents and stunt fire spread.

Also in the other side of the coin, since the volumes are closed, the ability to do prompt evacuation is necessary as fire produces a lot of air contaminants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/08/2022 02:13 pm
Fire protection (mostly firefighting but also fire prevention) could be aided by having control of the atmosphere.

For example in normal pressure (101kPa) atmosphere lowering oxygen content to 16% is well tolerated by people but makes common materials like wood and paper non-flammable. You rather don't want to have it that way permanently as it likely reduces physical performance of people, but in case of fire emergency you can shift atmosphere contents and stunt fire spread.

Also in the other side of the coin, since the volumes are closed, the ability to do prompt evacuation is necessary as fire produces a lot of air contaminants.
I'd be surprised if you could take the oxygen out fast enough,  but having the habitats at lower pressure, let's say 80 kPa, and quickly adding 20% of pure nitrogen to reach 100 kPa, rather like the Inergen fire fighting system does, might do the trick.  Would have to be quite extensive to act fast enough!
I would expect the habitats to have extensive smoke tight corridors, and various fire retarding walls, just like buildings today.  Having the first underground floor smoke tight, for example, plus a number of staircases up to the other floors, might be enough, with the main floor acting as a fire rated assembly.  500m to 1m of concrete sure stops a fire!
I would also expect the glass windows to be protected by a deluge water system just as similar arrangements are today in large atriums.  To prevent the fire heat breaking the windows.

Perhaps encourage using ceramics for surface finishes rather than paints, as well.  And I expect wood will not be a cheap construction material on Mars.



Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/08/2022 06:26 pm
Yes, not having flammable materials to begin with - careful with fabrics and liquids, and don't build everything out of wood...

Having moved to the US, I found that fire safety is a much bigger issue when residences are built out of wood, both frame and panels.  Concrete and masonary don't burn as well.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/08/2022 07:30 pm
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/08/2022 07:56 pm
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.
Oups! I failed to make myself clear.  Dust generated inside the habitats will not be too severe.  Preventing dust from entering the habitats will be a real challenge, for all the excellent reasons you mention.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/08/2022 07:57 pm
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.
Though you do mention a solution: high humidity / water aerosol
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/09/2022 01:51 am
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.
Though you do mention a solution: high humidity / water aerosol
Yes, water aerosol shower in multi-step process.

From outside, enter room 1 for detergent shower and rinse off spacesuit surface.by another suited person; remove suit and step into room 2 for vacuum of whole body, then step into habitat interior. Dust captured by water goes into floor drain, then piped to chemical treatment, then to  basin to settle out waste solids.

A little different from entering a room on Earth.  :P
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/09/2022 02:03 am
When you exit your habitat you may be asked to take along a closed container of dried dust. When outside, you may open the container and release the dust into the wind. This is perfectly acceptable and environmentally sound on Mars.  ;)
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/09/2022 02:13 am
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.
Though you do mention a solution: high humidity / water aerosol
Yes, water aerosol shower in multi-step process.

From outside, enter room 1 for detergent shower and rinse off spacesuit surface.by another suited person; remove suit and step into room 2 for vacuum of whole body, then step into habitat interior. Dust captured by water goes into floor drain, then piped to chemical treatment, then to  basin to settle out waste solids.

A little different from entering a room on Earth. 
Basically yes, but without being intentionally over elaborate.

Walk through a tube where the aerosol is blowing in the opposite direction.  Or just use a water shower - as you pointed out, once the dust is wet it stops being a problem.  Cleaning the water then becomes trivial.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/09/2022 02:26 am
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.
Though you do mention a solution: high humidity / water aerosol
Yes, water aerosol shower in multi-step process.

From outside, enter room 1 for detergent shower and rinse off spacesuit surface.by another suited person; remove suit and step into room 2 for vacuum of whole body, then step into habitat interior. Dust captured by water goes into floor drain, then piped to chemical treatment, then to  basin to settle out waste solids.

A little different from entering a room on Earth. 
Basically yes, but without being intentionally over elaborate.

Walk through a tube where the aerosol is blowing in the opposite direction.  Or just use a water shower - as you pointed out, once the dust is wet it stops being a problem.  Cleaning the water then becomes trivial.
I hope you are right. But one should avoid direct skin contact with micro-micro-particles that could easily enter the body. We don't know if they will simply pass through or accumulate in the body.

Aded: Your wind tunnel idea could be adopted for room 2.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Ionmars on 03/09/2022 02:32 am
Note to HVAC engineers: Habitat air should flow from room 2 to room 1 to help retain dust in room 1.

Note to Sanitary Engineers: Shower water from room 1 should be chemically treated to aggregate micro-particles into larger size particles, to render them harmless.
Title: Re: Envisioning Amazing Martian Habitats
Post by: meekGee on 03/09/2022 03:10 am
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.
Though you do mention a solution: high humidity / water aerosol
Yes, water aerosol shower in multi-step process.

From outside, enter room 1 for detergent shower and rinse off spacesuit surface.by another suited person; remove suit and step into room 2 for vacuum of whole body, then step into habitat interior. Dust captured by water goes into floor drain, then piped to chemical treatment, then to  basin to settle out waste solids.

A little different from entering a room on Earth. 
Basically yes, but without being intentionally over elaborate.

Walk through a tube where the aerosol is blowing in the opposite direction.  Or just use a water shower - as you pointed out, once the dust is wet it stops being a problem.  Cleaning the water then becomes trivial.
I hope you are right. But one should avoid direct skin contact with micro-micro-particles that could easily enter the body. We don't know if they will simply pass through or accumulate in the body.
Well you're wearing a vacuum suit, right?  Start by going into a submersion bath and serious industrial-power shower.  De-suit and do it again nekkid.

The suit then gets cleaned again before re-use
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/09/2022 09:41 am
When you exit your habitat you may be asked to take along a closed container of dried dust. When outside, you may open the container and release the dust into the wind. This is perfectly acceptable and environmentally sound on Mars.  ;)
Dust from outside the habitat will be an issue if it gets inside, but there are many possible measures that can be taken to stop this happening such as vacuuming, electrostatic precipitation, water washing etc. The very fine dust will not remain very fine for long after contact with water and organic matter it will coagulate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/09/2022 09:59 am
Use of water for cleaning would mean that the architecture would need to be at least partially water resistant.
If this is not the case, there are other methods to clean.  After all, Mars as an interior space will not have interior deserts or volcanoes that generate large amounts of dust, so Mars might be less dusty than Earth, within the habitats.  Rubbing down the floors with wet rags and general dusting with electrostatic swifters might be enough :-)

The will be multiple spills though, throughout a year, ranging from forgotten sink taps to breaks in water and drain pipes.  In particular as the infrastructures age.  So some though needs to go into the detail of this, if we don't want surprise and catastrophic underground rust spots eating through our habitat's envelope.  That's another reason why having a visible and exposed envelope might be a good idea:  easier maintenance over the years (centuries??). 
I disagree -- dust will be a major problem.

Over millennia, airborne dust circulated around the planet, gradually eroding into smaller and smaller particles. Today much of the airborne particulate matter is of molecular size and is easily carried aloft, even in Mars thin atmosphere. On Earth; water adheres to dust particles and they rain out of the air. It does not rain out on Mars because of the absence of aerial moisture. One common dust molecule on Mars is ferric oxide (Fe2O3), a red ore = rust. It is so prominent in the atmosphere that it gives the whole planet a red hue (the red planet).
 
Breathing Mars dust could be lethal. Dust Particles of less than 5 microns can penetrate into the gas exchange region of human lungs. In the US, the EPA has defined a hazardous particulate size to be less than 2.5 microns. A particle size measured in Angstrom units is unknown on Earth so the body's reaction to it is also unknown, but presumed dangerous. It would enter through the lungs and likely through every pore of the body.

The dust phenomenon must be a factor in designing Mars habitats, especially at entrances.

I expect there will be a lot of concrete aprons around Mars habitats to mitigate that. Possibly with some kind of electrostatic cleaning grid and leaf-blower bots to clean off the dust that accumulates.

But yes: dust is a major health hazard and not to be taken lightly.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/11/2022 03:48 am
I don't think people will be going out much.  Most of the time will be spent 'indoors'.
If you live in a tunnel, you'll also move about in tunnels.  until you want to go a bit further out....
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/11/2022 08:11 am
I don't think people will be going out much.  Most of the time will be spent 'indoors'.
If you live in a tunnel, you'll also move about in tunnels.  until you want to go a bit further out....


Love that Jetsons-like RV. I can practically smell the tobacco smoke and pleather interior. I can also imagine people going ice-fishing in pressure suits.

Looking at your hab sausages, have you considered a concertina-like arrangment of mirrored steel plates and glass? With the steel and glass plates at 45 degrees, that would turn the exterior into a kind of fresnel lens (but not actually focusing anything, just serving to admit extra light and view).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/11/2022 03:19 pm
I don't think people will be going out much.  Most of the time will be spent 'indoors'.
If you live in a tunnel, you'll also move about in tunnels.  until you want to go a bit further out....


Love that Jetsons-like RV. I can practically smell the tobacco smoke and pleather interior. I can also imagine people going ice-fishing in pressure suits.

Looking at your hab sausages, have you considered a concertina-like arrangement of mirrored steel plates and glass? With the steel and glass plates at 45 degrees, that would turn the exterior into a kind of fresnel lens (but not actually focusing anything, just serving to admit extra light and view).
Sounds like a fun arrangement.  Might be difficult to arrange the plates to transmit structural tension in such a system. 
I would expect the habitat developers/inhabitants to create special features to make their habitats more attractive to the eventual inhabitants, and that older arrangements might go out of fashion and be replaced.  The lifetime of the individual habitats may be limited by maintenance costs or obsolescence of secondary systems.
Since due to radiation protection requirements there are some large blank walls in the design, that can be seen as an opportunity for decoration, or green walls.  We had though that large landscape images might be wrapped on the stainless steel surfaces or on exterior slopes, rather like the images used for wrapping a car.  Esthetic advantage would have to be weighted against fire risk, I expect
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/15/2022 04:15 am
After reading the Wikipedia article on Earthships, I don't see much difference with what I'm doing as far as the main buildings go.  Scale perhaps.  Energy, garbage, sewage, shelter, clean water and food.  Got them all.  Recycled materials may not be possible at first, but I expect the first habitats will be recycled with time.

Yes I know. I was referring to the aesthetic attributes. That's why I said "Google Image search Earthships," not "read the Wikipedia article on Earthships." ;)


If you're looking to read about how to achieve the Earthship aesthetic, I don't think there are any good texts online (least of all Wikipedia!). If that's what you seek, A Pattern Language is still the best source out there.

I have separated the pressure envelope function from the building function.  It's not a function found on Earth anyway.

This is sort of like designing a skyscraper with a "separate columns" for holding up the floors above you, citing the fact that "it's not a function found in one-story buildings anyway.".

To preemptively clarify: I mean literally having the columns as a separate isolated disconnected structure (ala the pressure vessel in the Mars renderings), not just that the columns are individual components of one integrated structure (which is how skyscrapers are actually built).

Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 03/15/2022 05:15 am
I don't think people will be going out much.  Most of the time will be spent 'indoors'.
If you live in a tunnel, you'll also move about in tunnels.  until you want to go a bit further out....


Love that Jetsons-like RV. I can practically smell the tobacco smoke and pleather interior. I can also imagine people going ice-fishing in pressure suits.

Looking at your hab sausages, have you considered a concertina-like arrangement of mirrored steel plates and glass? With the steel and glass plates at 45 degrees, that would turn the exterior into a kind of fresnel lens (but not actually focusing anything, just serving to admit extra light and view).
Sounds like a fun arrangement.  Might be difficult to arrange the plates to transmit structural tension in such a system. 
I would expect the habitat developers/inhabitants to create special features to make their habitats more attractive to the eventual inhabitants, and that older arrangements might go out of fashion and be replaced.  The lifetime of the individual habitats may be limited by maintenance costs or obsolescence of secondary systems.
Since due to radiation protection requirements there are some large blank walls in the design, that can be seen as an opportunity for decoration, or green walls.  We had though that large landscape images might be wrapped on the stainless steel surfaces or on exterior slopes, rather like the images used for wrapping a car.  Esthetic advantage would have to be weighted against fire risk, I expect

I expect there's some kind of refractive material arrangement as well that could be used to channel light from the outside to the inside, or to mask the struts. Like the lenticular lens arrangements that "invisibility" materials are made of. Since you are mostly looking at neighbouring horizontally-laying buildings on the outside, and a largely blank Martian sky, any smearing effect would be aesthetically minimal.

https://interestingengineering.com/invisibility-cloaks-are-no-longer-just-science-fiction

The advantage of masking the solid supports is that you could use more, smaller-width windows and supports if you wanted.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/15/2022 05:30 am
Can an argument be made that vast open areas add inertia to the system, and therefore have a use or even provide some measure of safety?

Larger volumes are inherently more safe because they lose pressure more slowly, as oldAtlasEguy showed.

Sounds like an extremely expensive way to buy risk reduction.

Redundant compartments and automatic air refill systems (which you need anyway) are cheaper approaches than "waste most of the space."

At 30m height, you start to get micro-climates forming. By putting the sausages on a slope you might get quite a bit of circulation within them. That is an advantage for TripD's arrangement.

What exactly is the "advantage" again?

Also, a slight slope would increase illumination into the sausages. Running north-south you could angle the windows to the sun, effectively corrugating the tube, but achieve >50% daylighting.

For maximum sunlight you want a building that orients the long direction east-west, not north-south.


Also, at very large sizes (eg 200m diameter domes) pressurised volumes start to add a significant amount of radiation shielding from air mass, which works out to ~12g/cm^2 for every 100m of sea level air thickness.

Again this is the fantastically expensive way to do it.

I guess I should have clarified: are there any non-zero advantages that are actually worth the enormous cost??
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/15/2022 07:15 am
For fire protection, we should plan for sprinklers everywhere, including any large open areas.  The areas should be subdivided so deluge systems could be used for these large areas, as is done in aircraft hangars, for example.  The same system could be used to create localized rain, that can be used for cleaning and for watering plants.  If the large habitats are installed with a 1-2 degree slope they will drain by gravity.  Large water tanks are a given anyway for many reasons.  Fire protection reservoirs are already a feature of all Earth cities.

A sump tank at the lowest point would also work, with periodic drains. No need for the entire structure to slope at 1-2°.

Reverse osmosis membrane separation is already used for soil remedial operation of contamination by perchlorates.
It requires a lot of clean water though, so there would have to be an external source of clean water.
So a typical habitat might have a sanitary waste water treatment system, and a 'rain water' treatment system.  Plenty of water will be required for irrigation anyway, so might as well use it for general cleaning first.

If you have lots of plants, the primary water source will be the dehumidification system needed to remove all that transpired water.


As each human produces, among other things, about 3 kg of skin flakes per year, that works out to about one tonne of dust for a 300 person habitat, per year.  Plus all the hair and many times more than that for the  plants debris over the year.  All eventual food for a bacteria based water treatment system or compost generation units.

This will get swept up in the vacuuming waste. If you have lots of plastics (the big culprit being artificial fibers in clothes, but also building materials like vinyl flooring), then this detritus will be hopelessly cobtaminated with microplastics, so you'd want to incinerate it rather than incorporate it in your closed-loop ecology.

Wool clothing has been shown in NASA studies to require less washing and smell less, so that's another plus. It also increases thermal comfort, and modern merino fibers don't have the itchiness problems of those old Christmas sweaters. :D

It's a common, and conservative, metric to use 10 l/s per person of fresh air.  So that means 3000 l/s for a 300 person habitat, or about 6000 cfm.  That is not a very large piece of equipment.  Would be some kind of CO2 scrubber, as well as capturing composite organic volatiles such as methane.  Air handling equipment for temperature control and general ventilation might take the form of large fans, or perhaps a convective cycle using heat and cold, if than can be applied.  Depends a bit on the scale of things.  There would have to be some kind of condensation apparatus that remove excess humidity, in particular if lots of plants are present in the common areas.

Compost-based air filters (which can be as simple as pumping ambient air through your planter bed soil) can regeneratively remove this class of air pollution.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 03/15/2022 11:53 am
People like big open spaces, even if it’s expensive. And I think the cost per unit volume of large open space will be less than smaller compartments.
Title: Re: Envisioning Amazing Martian Habitats
Post by: sghill on 03/15/2022 12:39 pm
People like big open spaces, even if it’s expensive. And I think the cost per unit volume of large open space will be less than smaller compartments.

Likes and needs are two different things. It is a very modern thought that big spaces are necessary for mental well-being.

The biggest spaces, IMHO, will be cafeteriums.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 03/15/2022 12:51 pm
People like big open spaces, even if it’s expensive. And I think the cost per unit volume of large open space will be less than smaller compartments.

Likes and needs are two different things. It is a very modern thought that big spaces are necessary for mental well-being.

The biggest spaces, IMHO, will be cafeteriums.
Ive lived in places where you can’t go outside for significant parts of the year. You cherish large open spaces in such times. Indoor zoos, even malls, help with the seasonal affective disorder you get at those times of year.

It doesn’t have to be everywhere. But it should be somewhere.

And no, I don’t think it’s a “modern notion.” We used to spend more time outdoors, not less.

When it comes to mental well-being, there’s a continuum between likes and wants, not a firm line. And mental well-being is essential for human thriving on Mars long-term.

Poor morale reduces productivity and the chance of survival.

Pack them in like sardines for transit. But when the humans get to Mars, they will want and need “Amazing Martian Habitats.” :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/15/2022 03:16 pm
After reading the Wikipedia article on Earthships, I don't see much difference with what I'm doing as far as the main buildings go.  Scale perhaps.  Energy, garbage, sewage, shelter, clean water and food.  Got them all.  Recycled materials may not be possible at first, but I expect the first habitats will be recycled with time.

Yes I know. I was referring to the aesthetic attributes. That's why I said "Google Image search Earthships," not "read the Wikipedia article on Earthships." ;)


If you're looking to read about how to achieve the Earthship aesthetic, I don't think there are any good texts online (least of all Wikipedia!). If that's what you seek, A Pattern Language is still the best source out there.

I have separated the pressure envelope function from the building function.  It's not a function found on Earth anyway.

This is sort of like designing a skyscraper with a "separate columns" for holding up the floors above you, citing the fact that "it's not a function found in one-story buildings anyway.".

To preemptively clarify: I mean literally having the columns as a separate isolated disconnected structure (ala the pressure vessel in the Mars renderings), not just that the columns are individual components of one integrated structure (which is how skyscrapers are actually built).
It’s called a curtain wall.  Most sky scrapers do separate structure from enveloppe even on Earth.  Also non load bearing walls throughout the interior.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/15/2022 03:25 pm
For fire protection, we should plan for sprinklers everywhere, including any large open areas.  The areas should be subdivided so deluge systems could be used for these large areas, as is done in aircraft hangars, for example.  The same system could be used to create localized rain, that can be used for cleaning and for watering plants.  If the large habitats are installed with a 1-2 degree slope they will drain by gravity.  Large water tanks are a given anyway for many reasons.  Fire protection reservoirs are already a feature of all Earth cities.

A sump tank at the lowest point would also work, with periodic drains. No need for the entire structure to slope at 1-2°.

Reverse osmosis membrane separation is already used for soil remedial operation of contamination by perchlorates.
It requires a lot of clean water though, so there would have to be an external source of clean water.
So a typical habitat might have a sanitary waste water treatment system, and a 'rain water' treatment system.  Plenty of water will be required for irrigation anyway, so might as well use it for general cleaning first.

If you have lots of plants, the primary water source will be the dehumidification system needed to remove all that transpired water.


As each human produces, among other things, about 3 kg of skin flakes per year, that works out to about one tonne of dust for a 300 person habitat, per year.  Plus all the hair and many times more than that for the  plants debris over the year.  All eventual food for a bacteria based water treatment system or compost generation units.

This will get swept up in the vacuuming waste. If you have lots of plastics (the big culprit being artificial fibers in clothes, but also building materials like vinyl flooring), then this detritus will be hopelessly cobtaminated with microplastics, so you'd want to incinerate it rather than incorporate it in your closed-loop ecology.

Wool clothing has been shown in NASA studies to require less washing and smell less, so that's another plus. It also increases thermal comfort, and modern merino fibers don't have the itchiness problems of those old Christmas sweaters. :D

It's a common, and conservative, metric to use 10 l/s per person of fresh air.  So that means 3000 l/s for a 300 person habitat, or about 6000 cfm.  That is not a very large piece of equipment.  Would be some kind of CO2 scrubber, as well as capturing composite organic volatiles such as methane.  Air handling equipment for temperature control and general ventilation might take the form of large fans, or perhaps a convective cycle using heat and cold, if than can be applied.  Depends a bit on the scale of things.  There would have to be some kind of condensation apparatus that remove excess humidity, in particular if lots of plants are present in the common areas.

Compost-based air filters (which can be as simple as pumping ambient air through your planter bed soil) can regeneratively remove this class of air pollution.
All good points. Just the small caveat the plants are not a water source in this specific case but just the top water user.  The source will be ‘the outside’.  Sprinklers are a potential delivery system, but pipelines or small self driving water trucks might be better.  I saw small trucks in aSpainish city where  it doesn’t rain much.
Title: Re: Envisioning Amazing Martian Habitats
Post by: oldAtlas_Eguy on 03/15/2022 03:56 pm
Yes. It is probably a good idea to keep the Humidity level at or above 60% to reduce static electric discharges which can start fires. So the Humidity level will be rigorously controlled to keep it from being to uncomfortable. The about 60% level is probably close to the most comfortable eliminating/mitigating many problems.

A controlled directed watering system maybe a lot better in that it does not raise the Humidity level much. But every so often a general "rain" to wash away the dust collection on surfaces in the habitat. A once a month event possibly. So for that case as well as that same "rain" system for fire suppression needs somewhere for all that water to run off to. Also a drain along the bottom of the planters to remove excess water is needed as well. This water can be simply filtered and treated for then refill of the tanks that are used for holding the water for this "rain" fire suppression system.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MarkXal on 03/15/2022 06:12 pm
HVAC engineer here, 60% is pretty high and borderline uncomfortable. In buildings on Earth 45%-55% is generally the target.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/16/2022 11:14 am
HVAC engineer here, 60% is pretty high and borderline uncomfortable. In buildings on Earth 45%-55% is generally the target.
Yes!  People aren't plants. Don't expect ultra high productivity and comfort in spaces we share with them.
Title: Re: Envisioning Amazing Martian Habitats
Post by: MarkXal on 03/16/2022 12:00 pm
HVAC engineer here, 60% is pretty high and borderline uncomfortable. In buildings on Earth 45%-55% is generally the target.
Yes!  People aren't plants. Don't expect ultra high productivity and comfort in spaces we share with them.

woops sorry, I didn't read far back enough!
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/16/2022 12:31 pm
HVAC engineer here, 60% is pretty high and borderline uncomfortable. In buildings on Earth 45%-55% is generally the target.
Yes!  People aren't plants. Don't expect ultra high productivity and comfort in spaces we share with them.

woops sorry, I didn't read far back enough!
It's a long thread.   HVAC engineer myself :-)  Glad to have comments and criticism!
Title: Re: Envisioning Amazing Martian Habitats
Post by: webdan on 03/16/2022 12:45 pm
There's a joke in here, about 2 HVAC engineers on Mars discussing the best way to...

 ;D
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/16/2022 01:29 pm
There's a joke in here, about 2 HVAC engineers on Mars discussing the best way to...

 ;D
Two HVAC engineers walk into a bar... of course they talk about architecture.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/17/2022 03:39 am
Turning a little bit political, but it does give me the possibility of showing of other parts of the town before she sets off on the Meridian way...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 03/17/2022 12:27 pm
People like big open spaces, even if it’s expensive. And I think the cost per unit volume of large open space will be less than smaller compartments.

Likes and needs are two different things. It is a very modern thought that big spaces are necessary for mental well-being.

The biggest spaces, IMHO, will be cafeteriums.
Ive lived in places where you can’t go outside for significant parts of the year. You cherish large open spaces in such times. Indoor zoos, even malls, help with the seasonal affective disorder you get at those times of year.

It doesn’t have to be everywhere. But it should be somewhere.

And no, I don’t think it’s a “modern notion.” We used to spend more time outdoors, not less.

When it comes to mental well-being, there’s a continuum between likes and wants, not a firm line. And mental well-being is essential for human thriving on Mars long-term.

Poor morale reduces productivity and the chance of survival.

Pack them in like sardines for transit. But when the humans get to Mars, they will want and need “Amazing Martian Habitats.” :)
As you say there is a continuum between likes and wants. There is also a continuum between small spaces and big spaces. It seems likely that the size of space available will grow with the size of any base / colony over time.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 03/17/2022 01:48 pm
The story is going to go to a smaller settlement/city that is less prosperous and 'Elysium' like than Surya.
This habitat will be designed in the next few weeks (or years!  no deadline :-)
So for anyone who feels that Surya is unrealistic and overblown, or just poorly designed, I'm open to suggestions.

It may be/include repurposed fist stage settlements, so that would be a way of seeing these elsewhere than in the Arkadia history museum (Image by Remy Navarro) .
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2022 03:52 am
People like big open spaces, even if it’s expensive. And I think the cost per unit volume of large open space will be less than smaller compartments.

"Cost per unit volume" isn't the critical optimization metric. "Cost benefit ratio" is the critical metric.

You're using a lot of volume (which, as the name suggests, gets multiplied by that cost per unit volume), so it's still a large cost for a small benefit.



It is a very modern thought that big spaces are necessary for mental well-being.


And no, I don’t think it’s a “modern notion.” We used to spend more time outdoors, not less.

You might notice that these are actually two different things.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2022 04:04 am
After reading the Wikipedia article on Earthships, I don't see much difference with what I'm doing as far as the main buildings go.  Scale perhaps.  Energy, garbage, sewage, shelter, clean water and food.  Got them all.  Recycled materials may not be possible at first, but I expect the first habitats will be recycled with time.

Yes I know. I was referring to the aesthetic attributes. That's why I said "Google Image search Earthships," not "read the Wikipedia article on Earthships." ;)


If you're looking to read about how to achieve the Earthship aesthetic, I don't think there are any good texts online (least of all Wikipedia!). If that's what you seek, A Pattern Language is still the best source out there.

I have separated the pressure envelope function from the building function.  It's not a function found on Earth anyway.

This is sort of like designing a skyscraper with a "separate columns" for holding up the floors above you, citing the fact that "it's not a function found in one-story buildings anyway.".

To preemptively clarify: I mean literally having the columns as a separate isolated disconnected structure (ala the pressure vessel in the Mars renderings), not just that the columns are individual components of one integrated structure (which is how skyscrapers are actually built).
It’s called a curtain wall.  Most sky scrapers do separate structure from enveloppe even on Earth.

I even preemptively clarified that that was not what I meant, and yet I was still misunderstood (and in exactly the way I predicted)......   *facepalm*


Also non load bearing walls throughout the interior.

Same. But the interior of a skyscraper is packed with load-bearing columns, not a separate isolated not touching structure around it (which is what I meant from the beginning).

Totally separate. Two separate things. Not intermeshed within each other, but just one object inside another like a ship in a bottle. That's what I meant when I said "separate structure."

That is _not_ how we design skyscrapers, but it (weirdly, to me) _is_ the architecture of these proposed Mars buildings.

Is it clear yet? Do I need to clarify more?



Edit: This matters because it results in an inefficient use of materials. We need to pay the full structure penalty of holding the weight of the radiation shield, and also the full penalty of the tensile load from the internal atmosphere.

Both of these loads are large (indeed, dominant: everything else is practically a rounding error), so the resulting design penalty is also large.

In an optimized design we could combine these two structures and save mass/cost: a single tensile/compressive beam that carries both loads. At its compressive limit it is strong enough to hold up the shield depressurized, and in its tensile limit it's strong enough to hold the internal pressure load minus the radiation shield weight. Both the mere act of combining structures and this subtraction result in cost savings.

In my preferred implementation, the radiation "slab" would simply be the regolith on the top floor (which is entirely planted in a high productivity forest garden), plus overhead water tanks to provide modest shielding for the garden. This provides "amazing" and psychologically-beneficial spaces, while still devoting the vast majority of interior volume to high-density multi-level usable space.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2022 04:24 am
Reverse osmosis membrane separation is already used for soil remedial operation of contamination by perchlorates.
It requires a lot of clean water though, so there would have to be an external source of clean water.
So a typical habitat might have a sanitary waste water treatment system, and a 'rain water' treatment system.  Plenty of water will be required for irrigation anyway, so might as well use it for general cleaning first.

If you have lots of plants, the primary water source will be the dehumidification system needed to remove all that transpired water.

All good points. Just the small caveat the plants are not a water source in this specific case but just the top water user. The source will be ‘the outside’.

I shouldn't have shortened it, and should have said the primary clean water source, which is what you were talking about.

Plants take (optionally) dirty water (read: nutrient-laden water) in, and put clean water out. Essentially they act as a "free" evaporator surface, ie one side of a distillation-based water purification system. When you realize that that's the side of the system that's energy-sucking, fouling-prone, and maintenance-hungry, this becomes an unexpectedly nice bonus feature.

For higher plants, this evaporation process consumes roughly 50% of the light energy striking the leaf. This number is useful to know when doing napkin math.  :D

  Sprinklers are a potential delivery system, but pipelines or small self driving water trucks might be better.  I saw small trucks in aSpainish city where  it doesn’t rain much.

Almost certainly water would be delivered via drip irrigation, or possibly a piped ceramic system: buried unglazed clay containers act as a maintenance-free automatic-soil-moisture-sensing flow regulator, with a pipe network feeding each one via a simple gravity-fed (hydrostatic equilibrium) mechanism.

High efficiency performance, low cost, low maintenance, high reliability, high ISRU manufacturability.



(if you're assuming hydro, that type of "water" is a whole other story :D)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 03/28/2022 06:54 am
Instead of lawns and pavement, ISTM that it's better aesthetically, psychologically, _and_ productivity-wise if the sunlit areas looked more like this:

https://www.youtube.com/watch?v=oLTGjiYHHbI#t=36
Title: Re: Envisioning Amazing Martian Habitats
Post by: EnricoR on 03/28/2022 05:59 pm
Something like this, but BIG ?

https://www.ideegreen.it/bioedilizia-earthship-63652.html (https://www.ideegreen.it/bioedilizia-earthship-63652.html)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/06/2022 11:24 am
Almost afraid to restart this thread, but ICON is working with NASA to produce Mars Dune Alpha, a 3D printed habitat for their CHAPEA Mars simulation. I find the construction of their notional building to be interesting - a rectangular building that bulges out to even hoop stress (the corners don't care). The walls in the render (but not the one being built on Earth) also seem to be slightly concave.

Also, OLTARIS has implemented lunar and Martian surface options for slab and sphere geometries, so I'm about to go and crash their servers.*



*jk
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/07/2022 03:27 pm
Found an interesting diagram from here: https://qz.com/2045601/mars-dune-alpha-inside-nasas-starchitect-designed-mars-habitat/

"Gradients of privacy"

Always nice to see Alexandrian design principles (https://www.iwritewordsgood.com/apl/patterns/apl127.htm) out there in the world.
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 12/07/2022 03:48 pm
Interesting. I have long felt that interplanetary spacecraft and planetary bases need to have a small solo privacy quiet area where a person can schedule alone time away from all others.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Barley on 12/07/2022 06:23 pm
Interesting. I have long felt that interplanetary spacecraft and planetary bases need to have a small solo privacy quiet area where a person can schedule alone time away from all others.
I'm not sure that's much of a problem in anything larger than a capsule.  In a cube farm people hide in conference rooms, labs, the library, the achieves, dead end corridors, ... . In extremis it's been known for somebody to ride a man-up truck to the top of the high-bay for couple of hours of peace and quiet.  Laptops were a huge improvement in quality of life and work.

The people who believe in scheduling alone time in dedicated places* are likely to be a bigger problem.  They should be encouraged to hangout in the airlock.

* or cube farms.
Title: Re: Envisioning Amazing Martian Habitats
Post by: InterestedEngineer on 12/07/2022 08:41 pm
Interesting. I have long felt that interplanetary spacecraft and planetary bases need to have a small solo privacy quiet area where a person can schedule alone time away from all others.
I'm not sure that's much of a problem in anything larger than a capsule.  In a cube farm people hide in conference rooms, labs, the library, the achieves, dead end corridors, ... . In extremis it's been known for somebody to ride a man-up truck to the top of the high-bay for couple of hours of peace and quiet.  Laptops were a huge improvement in quality of life and work.

The people who believe in scheduling alone time in dedicated places* are likely to be a bigger problem.  They should be encouraged to hangout in the airlock.

* or cube farms.

Not being a Navy person, how does the Navy handle this kind of requirement on an aircraft carrier or cruiser?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/07/2022 09:05 pm
Interesting. I have long felt that interplanetary spacecraft and planetary bases need to have a small solo privacy quiet area where a person can schedule alone time away from all others.
I agree. But it shouldn’t need to be scheduled. I think every person ought to at least have a personal bunk that they can keep their (few) personal items.

Maybe you could do a sort of pseudo-hotbunking where the bunks can expand or contract based on which shift is active, like those library shelves that can move.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Lampyridae on 12/08/2022 07:23 am
Here's a link to a conference paper detailing the habitat's construction, which I forgot to attach:

https://www.researchgate.net/publication/363740162_Constructing_NASA's_Crew_Health_and_Performance_Exploration_Analog_CHAPEA_A_3D-Printed_Habitat_by_ICONBIG

It has a good number of images of the interior. What it offers is experiences integrating Earth-brought elements into the 3D printing construction process.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/16/2022 02:22 am
Here's a link to a conference paper detailing the habitat's construction, which I forgot to attach:

https://www.researchgate.net/publication/363740162_Constructing_NASA's_Crew_Health_and_Performance_Exploration_Analog_CHAPEA_A_3D-Printed_Habitat_by_ICONBIG

It has a good number of images of the interior. What it offers is experiences integrating Earth-brought elements into the 3D printing construction process.

It seems they designed the passive solar details to be exactly backwards.  :-\


For optimum solar heating you want the long axis facing East-West, with lots of windows on the equator-facing side and lots of insulation on the pole-facing side. They have arranged the long side North-South, with no glazing and no insulation.

To optimum for passive cooling you still want an East-West orientation, except 1) no windows, and 2) insulate the equator-facing side more than the pole-facing side.

If you want both (eg for summer vs winter), add moveable shades to the windows and use switchable insulation on the North and South side.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/16/2022 04:01 pm
Interesting. I have long felt that interplanetary spacecraft and planetary bases need to have a small solo privacy quiet area where a person can schedule alone time away from all others.
They were provided for nearly fifty years ago in the Enterprise deck plans (1973) !!!  :D
PR= Personal Isolation Room.
Title: Re: Envisioning Amazing Martian Habitats
Post by: philw1776 on 12/16/2022 06:16 pm
Never knew that! Watched the show but was never a Trekkie. Just think that when crowded together it is a good thing to be able to take some brief quiet time alone now & then. Not accommodating hermits, just normal passengers/colonists, whatever the phrases are this month.

P.S. seriously appreciate and respect your valuable contributions to this thread & others.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/16/2022 06:50 pm
Never knew that! Watched the show but was never a Trekkie. Just think that when crowded together it is a good thing to be able to take some brief quiet time alone now & then. Not accommodating hermits, just normal passengers/colonists, whatever the phrases are this month.

P.S. seriously appreciate and respect your valuable contributions to this thread & others.
Thank you!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 12/16/2022 07:16 pm
Loving this positivity. :) 🥰 Continue!
Title: Re: Envisioning Amazing Martian Habitats
Post by: Slarty1080 on 12/17/2022 04:34 pm
Here's a link to a conference paper detailing the habitat's construction, which I forgot to attach:

https://www.researchgate.net/publication/363740162_Constructing_NASA's_Crew_Health_and_Performance_Exploration_Analog_CHAPEA_A_3D-Printed_Habitat_by_ICONBIG

It has a good number of images of the interior. What it offers is experiences integrating Earth-brought elements into the 3D printing construction process.

It seems they designed the passive solar details to be exactly backwards.  :-\


For optimum solar heating you want the long axis facing East-West, with lots of windows on the equator-facing side and lots of insulation on the pole-facing side. They have arranged the long side North-South, with no glazing and no insulation.

To optimum for passive cooling you still want an East-West orientation, except 1) no windows, and 2) insulate the equator-facing side more than the pole-facing side.

If you want both (eg for summer vs winter), add moveable shades to the windows and use switchable insulation on the North and South side.
I think the Moon's axis is only tilted by 1.5 degrees to the plane of the ecliptic so there won't be that much variation between summer and winter. If they are planning to use the habitat at the south pole then the sun is just going to roll around the horizon roughly once a month. Presumably they will put the habitat in near perpetual sunlight rather than darkness. It will make for some weird photography with the shadows and lighting. The nutters will have a field day with it.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/18/2022 03:52 pm
Agreed, thermal solutions on the Moon will look very different. I believe the design intent here was for Mars.

Quote
The 1,700 square-foot structure simulates a realistic Mars habitat...
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/18/2022 04:06 pm
We discussed a log time ago here on the thread a modular approach to building extensive surface habitats.  Thrn end result was a bit like the Mezquita in Cordoba, Spain.  We also discussed the question of how to do the edge modules, and the solution I though of at the time was incorrect.
If we did vertical walls as shown in the image, the discontinuity of the vertical walls would tear them apart. 
There might be a solution that allows a continuous transmission of force, or perhaps that relies on anchors and such?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/21/2022 09:00 pm
Nice renderings!

Is the material in any way ISRU?
Otherwise it looks very very ambitious.

I always thought that we should tranport the construction machinery to Mars, but would have to source 99 percent of the actual building materials locally for the whole project to make sense.

Just as will be done for the production of rocket fuel.

Transporting hi-tech and people to Mars makes sense. Raw materials not so much, to the extent it can be avoided.

That would also be the reason why Elon is so focused on perfecting tunnelling operations. Even the newest Boring Company tunnelling equipment at 21 feet diameter still fit just fine inside the 30 feet diameter Starships...   
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/21/2022 11:46 pm
Nice renderings!

Is the material in any way ISRU?
Otherwise it looks very very ambitious.

I always thought that we should tranport the construction machinery to Mars, but would have to source 99 percent of the actual building materials locally for the whole project to make sense.

Just as will be done for the production of rocket fuel.

Transporting hi-tech and people to Mars makes sense. Raw materials not so much, to the extent it can be avoided.

That would also be the reason why Elon is so focused on perfecting tunnelling operations. Even the newest Boring Company tunnelling equipment at 21 feet diameter still fit just fine inside the 30 feet diameter Starships...
Thanks!
Yes all ISRU.  The tension columns are steel, painted green for a 'natural' effect but probably not the best choice, after reflection.
The transparent materials is a descendent of flexible glass used for phone screens.  Glass is mostly SiO2, and that is in ample supply on Mars.  So steel and glass, also pretty much the most common building materials on Earth.
The cellular concept was mostly evolved by Twark_Main, but all design mistakes are my own.
I have since found the best way to finish the sides.  Make them continuous like a inflatable mattress.
Title: Re: Envisioning Amazing Martian Habitats
Post by: darkenfast on 12/22/2022 01:50 am
Interesting. I have long felt that interplanetary spacecraft and planetary bases need to have a small solo privacy quiet area where a person can schedule alone time away from all others.
I'm not sure that's much of a problem in anything larger than a capsule.  In a cube farm people hide in conference rooms, labs, the library, the achieves, dead end corridors, ... . In extremis it's been known for somebody to ride a man-up truck to the top of the high-bay for couple of hours of peace and quiet.  Laptops were a huge improvement in quality of life and work.

The people who believe in scheduling alone time in dedicated places* are likely to be a bigger problem.  They should be encouraged to hangout in the airlock.

* or cube farms.

Not being a Navy person, how does the Navy handle this kind of requirement on an aircraft carrier or cruiser?

If you're one of the peasants, you might get a curtain on your bunk. My deployments were in the middle of my career in the 80s, and there were still ships with no curtains on the bunks and sometimes back-to-back (no divider) with other bunks. Submarines still have some hot-bunking (usually three people sharing two bunks, sometimes two with one bunk).

Even something like a Japanese "capsule hotel" bunk would be a great improvement, if it were done well. 2.2X1.2X1.2 meters (plus locker space), would be fine by me.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/22/2022 03:04 am
There might be a solution that allows a continuous transmission of force, or perhaps that relies on anchors and such?

My approach is simple:

The bulk interior is composed of a 3D "graph paper" grid of tensile beams. The vertical beams both resist tension and hold up the structure if depressurized (this is ultimately what limits the maximum efficient height of structures).


The exterior is composed of spherically-curved panels that anchor to the rectilinear grid of tensile beams. The panels are double-layer with a vacuum-insulated interior space, which also allows instant detection of leaks, and recovery and recycling of any (costly) leaked atmosphere.

This avoids the "soap bubble" pressure vessel designs that are required to assume the shape of large spheres or cylinders. Instead, this type of structure can be made in standard rectilinear shapes (that optionally conform to the underlying terrain) similar to skyscrapers or split levels.

The top and sides are covered with inexpensive sifted regolith. Standard stabilized earth techniques are used to construct the vertical wall regolith shielding.

The roof might optionally be topped with a greenhouse structure, where water tanks shield the greenhouse itself and any dirt and/or hydroponic mass further shields the lower habitation levels.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 12/22/2022 03:09 am
Better view of the air mattress design.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/22/2022 03:18 am
Note that the "air mattress" is essentially a single-layer implementation of the 3D grid I described.  :D

Add a second "story" and you need a graph paper grid of beams to hold the walls in.

To add a third "story" you have two layers of grids.

Etc etc...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 12/22/2022 10:12 pm
How would buildings like these deal with temperature differences? And radiation?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/23/2022 01:44 am
Sifted regolith for radiation, evacuated MLI panels for thermal insulation. The panels might be inert, or they might feature switchable insulation for passive solar gain.

If you put the insulating panels outside the regolith radiation shield, then all that mass becomes a huge thermal battery. Effectively it becomes energy storage without the need to bring heavy batteries from Earth.
Title: Re: Envisioning Amazing Martian Habitats
Post by: geza on 12/23/2022 11:09 am
What are the connecting horizontal tubes on the picture? Walking routes? For air circulation?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/23/2022 05:01 pm
If you put the insulating panels outside the regolith radiation shield, then all that mass becomes a huge thermal battery. Effectively it becomes energy storage without the need to bring heavy batteries from Earth.

No, high operating temperature precludes hab use.

ISRU chemical batteries, e.g., salt water (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2048640#msg2048640) or iron (https://forum.nasaspaceflight.com/index.php?topic=53443.msg2306664#msg2306664), can operate efficiently beside, or under (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2312804#msg2312804), habs.  A 99% mass cut (https://forum.nasaspaceflight.com/index.php?topic=53443.msg2305349#msg2305349) is possible.
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/23/2022 06:34 pm
If you put the insulating panels outside the regolith radiation shield, then all that mass becomes a huge thermal battery. Effectively it becomes energy storage without the need to bring heavy batteries from Earth.

No, high operating temperature precludes hab use.

Not high operating temperature, obviously. ::)

These would instead be providing a large thermal buffer in a low-power emergency. Instead of the structure losing all its heat in a day or so, the internal temperature can "coast" for a while, due to the large amount of thermal mass located inside the thermal envelope.



Edit: Before LMT fires off a pithy reflex about low operating temperature precluding economical use, remember that we need the mass for radiation shielding anyway. This isn't a dedicated installation (what is being marketed as "thermal batteries" nowadays, which confused LMT), it's just a question of putting the insulation layer on the inside vs. the outside.

For inspection and repair you want the insulation on the outside anyway, so effectively you're getting a thermal battery for free.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/23/2022 08:08 pm
If you put the insulating panels outside the regolith radiation shield, then all that mass becomes a huge thermal battery. Effectively it becomes energy storage without the need to bring heavy batteries from Earth.

No, high operating temperature precludes hab use.

Not high operating temperature, obviously. ::)

These would instead be providing a large thermal buffer in a low-power emergency. Instead of the structure losing all its heat in a day or so, the internal temperature can "coast" for a while, due to the large amount of thermal mass located inside the building envelope.



Edit: Before LMT fires off a pithy reflex about low operating temperature precluding economical use, remember that we need the mass for radiation shielding anyway. This isn't a dedicated installation (what is being marketed as "thermal batteries" nowadays, which confused LMT), it's just a question of putting the insulation layer on the inside vs. the outside.

For inspection and repair you want the insulation on the outside anyway, so effectively you're getting a thermal battery for free.

Confused posts.  Cold dirt is not an energy store, insulator, or substitute for batteries.  It's a good heat sink.  Calculate.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/24/2022 02:19 am
Cold dirt

Nobody's talking about that.

I'm talking about room-temperature (or slightly above) dirt inside the thermal envelope, and equilibrated with the indoor temperature.

Using resistors or coolant pipes you can dump intermittent solar or waste heat into the center of the mass. This can time-shift heating load from times of high energy supply (eg midday) to times of low supply.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/28/2022 02:16 am
Using resistors or coolant pipes you can dump intermittent solar or waste heat into the center of the mass. This can time-shift heating load from times of high energy supply (eg midday) to times of low supply.

I neglected to mention, but this same concept works in reverse for cooling.

You can circulate chilled coolant through the mass during times of cooling over-supply (eg night), and dump waste heat into the mass during times of high demand. By time-shifting the cooling load you increase daily utilization, which reduces the size and cost of the cooling system.

It's good that it works both ways, because depending on the habitat design it can be either heating-dominated or cooling-dominated. I expect most habitat designs will be heating-dominated when running in low power ops mode (eg due to dust storms and/or malfunction).
Title: Re: Envisioning Amazing Martian Habitats
Post by: MickQ on 12/28/2022 03:13 am
I’m wondering how good this 3D printing process is going to be in making structures capable of containing any significant internal pressure.

Would habitat’s need to combine a printed insulating/structural layer with a polymer membrane to help keep the air in ?
Title: Re: Envisioning Amazing Martian Habitats
Post by: DanClemmensen on 12/28/2022 03:33 am
Using resistors or coolant pipes you can dump intermittent solar or waste heat into the center of the mass. This can time-shift heating load from times of high energy supply (eg midday) to times of low supply.

I neglected to mention, but this same concept works in reverse for cooling.

You can circulate chilled coolant through the mass during times of cooling over-supply (eg night), and dump waste heat into the mass during times of high demand. By time-shifting the cooling load you increase daily utilization, which reduces the size and cost of the cooling system.

It's good that it works both ways, because depending on the habitat design it can be either heating-dominated or cooling-dominated. I expect most habitat designs will be heating-dominated when running in low power ops mode (eg due to dust storms and/or malfunction).
You can use a heat pump instead of depending exclusively on passive heat movement. This reduces the size of the system even more. The same approach works here on Earth. On Mars, your thermal mass can just be the ground below the habitat. This is the equivalent of a ground-source heat pump on Earth. The extent to which you need to insulate your thermal mass from the rest of the ground will depend on the details of your heat budget, but I suspect that no such insulation is needed.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 12/31/2022 07:42 pm
Using resistors or coolant pipes you can dump intermittent solar or waste heat into the center of the mass. This can time-shift heating load from times of high energy supply (eg midday) to times of low supply.

I neglected to mention, but this same concept works in reverse for cooling.

You can circulate chilled coolant through the mass during times of cooling over-supply (eg night), and dump waste heat into the mass during times of high demand. By time-shifting the cooling load you increase daily utilization, which reduces the size and cost of the cooling system.

It's good that it works both ways, because depending on the habitat design it can be either heating-dominated or cooling-dominated. I expect most habitat designs will be heating-dominated when running in low power ops mode (eg due to dust storms and/or malfunction).
You can use a heat pump instead of depending exclusively on passive heat movement. This reduces the size of the system even more. The same approach works here on Earth. On Mars, your thermal mass can just be the ground below the habitat. This is the equivalent of a ground-source heat pump on Earth. The extent to which you need to insulate your thermal mass from the rest of the ground will depend on the details of your heat budget, but I suspect that no such insulation is needed.

No, the heat pump's COP crashes (https://acep.uaf.edu/media/81851/Ground-Source-Heat-Pumps-in-Cold-Climates.pdf) far above Mars temperatures. 

Actual insulation is needed, not conductive dirt.  Antarctic insulation R-value is ~ 70.   3 cm of Advance-R VIP (https://www.holcimelevate.com/content/dam/fsbp/migrated-document/us/en/60/605976.pdf) matches, at just 0.7 g/cm2.

Thermal buffer mass isn't needed, of course, but the mass of an ISRU saltwater (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2048640#msg2048640) battery farm could give perhaps 40 °C heat gratis (https://forum.nasaspaceflight.com/index.php?topic=39785.msg2312804#msg2312804), at any desired scale.

Understand Antarctic habs first.  If an idea doesn't work there, why would it work on Mars?


https://www.youtube.com/watch?v=dkpxUI_0TFw
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/31/2022 10:46 pm
Using resistors or coolant pipes you can dump intermittent solar or waste heat into the center of the mass. This can time-shift heating load from times of high energy supply (eg midday) to times of low supply.

I neglected to mention, but this same concept works in reverse for cooling.

You can circulate chilled coolant through the mass during times of cooling over-supply (eg night), and dump waste heat into the mass during times of high demand. By time-shifting the cooling load you increase daily utilization, which reduces the size and cost of the cooling system.

It's good that it works both ways, because depending on the habitat design it can be either heating-dominated or cooling-dominated. I expect most habitat designs will be heating-dominated when running in low power ops mode (eg due to dust storms and/or malfunction).
You can use a heat pump instead of depending exclusively on passive heat movement.

Indeed. I never meant to suggest otherwise!

On Mars, your thermal mass can just be the ground below the habitat.

I was specifically talking about exploiting the 2-5 m of radiation shielding regolith that you need anyway in the roof and walls. It makes sense for it to do "double duty."

Note that you almost certainly need insulation and/or cooling pipes below the habitat, just to prevent permafrost sublimation and destabilization. See construction techniques in northern Alaska. Smaller buildings are effectively built on stilts, but large buildings feature under-slab chiller loops.

Incidentally such chiller loops can effectively act as 100% effective insulation, reducing heat loss to zero or even negative!  :)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 12/31/2022 11:06 pm
No, the heat pump's COP crashes (https://acep.uaf.edu/media/81851/Ground-Source-Heat-Pumps-in-Cold-Climates.pdf) far above Mars temperatures.


I would maybe use a source that's less than a decade old, especially since there's been a lot of recent progress in this area.

https://electrek.co/2022/12/26/us-companies-are-producing-heat-pumps-that-work-below-20f/

For comparison:

https://www.researchgate.net/publication/337958459_GIS_analysis_of_promising_landing_sites_for_manned_flight_to_Mars

Actual insulation is needed

On this point we agree!
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/01/2023 04:23 pm
...use a source that's less than a decade old, especially since there's been a lot of recent progress in this area.

https://electrek.co/2022/12/26/us-companies-are-producing-heat-pumps-that-work-below-20f/

Not air source (https://electrek.co/2022/12/26/us-companies-are-producing-heat-pumps-that-work-below-20f/), but ground source (https://acep.uaf.edu/media/81851/Ground-Source-Heat-Pumps-in-Cold-Climates.pdf), very obviously.  Ugly pestering from Twark_Main.

--

Re video above (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445387#msg2445387): did posters notice that a heat exchanger is used at the Antarctic base? 

Why and where? 

Did they mention a heat pump?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/01/2023 06:21 pm
Coordinated ISRU Electrical and Thermal Batteries

Both chloride and carbonate salts are present in regolith.  ISRU saltwater batteries would use chloride salts.  Carbonate is waste.

That waste might be put to use in purely thermal batteries, e.g., at the largest industrial plants.  There the Cellcius thermal battery (https://innovationorigins.com/en/coal-merchants-new-style-heat-merchants-will-soon-drop-by-your-home-with-charged-salt-batteries-salt-batteries/) uses potassium carbonate and water to store waste heat energy via safe dehydration (https://cellcius.com/en/applications/industry/).  In practical terms, heat is stored without loss indefinitely, and shipped safely wherever needed.  In use, water and air recirculate, potentially through pre-existing ECLSS.  Energy density is ~ 0.75 GJ/m3 (Gaeini et al. 2019).

Here nearly all electrical and thermal battery mass is ISRU.

Refs.

Gaeini, M., Shaik, S.A. and Rindt, C.C.M., 2019. Characterization of potassium carbonate salt hydrate for thermochemical energy storage in buildings. (https://research.tue.nl/files/126214275/1_s2.0_S0378778818319315_main.pdf) Energy and Buildings, 196, pp.178-193.

https://www.youtube.com/watch?v=GgHLj3rxZAw
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/02/2023 01:29 am
I think the need for heating and cooling on Mars will be almost entirely determined by food production.
Food production on Earth depends on a heat/light source that is dispensing a peak of 1300 W/m2, with an average of about 250 W/m2 when you take the Earth area, albedo and night time into account.

The surface required for food production is at least one order of magnitude larger than the area required for housing.  Using hydroponics, intensive agriculture and multiple layers of production trays actually makes the cooling problem more acute, as the surface area available for cooling will be lower for the same amount of food production area.

Vacuum Insulated panels can easily reduce heat loss to values close to 10 W/m2 in average Martian conditions of -75C and 25C interior.  For summer days, the outside temperature can be significantly higher than -75C, reducing heat transfer further to a few Watts per m2.  So although the heat storage capacity of structural elements in a Martian settlement are interesting, they may not be useful all that often during a typical year.
I would rather expect a Martian settlement to be surrounded by cooling radiators in a configuration similar to standard ground source horizontal heat pipes.  And to avoid freezing at the very low ambiant temperatures, heat pumps may indeed be a good solution, as most circulating fluids may have freezing problems, circulating a gas might be a good alternative.  Operating pressure may be a problem?  Would be interesting to work out an arrangement.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/02/2023 01:29 am
...use a source that's less than a decade old, especially since there's been a lot of recent progress in this area.

https://electrek.co/2022/12/26/us-companies-are-producing-heat-pumps-that-work-below-20f/

Not air source, but ground source, very obviously.

Obviously. That changes nothing about what I wrote.

Ugly pestering from Twark_Main.

Play nice with the other kids.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/02/2023 01:37 am
I think the need for heating and cooling on Mars will be almost entirely determined by food production.
Food production on Earth depends on a heat/light source that is dispensing a peak of 1300 W/m2, with an average of about 250 W/m2 when you take the Earth area, albedo and night time into account.

The surface required for food production is at least one order of magnitude larger than the area required for housing.  Using hydroponics, intensive agriculture and multiple layers of production trays actually makes the cooling problem more acute, as the surface area available for cooling will be lower for the same amount of food production area.

Agreed. This is why I expect cooling-dominated structures to gradually replace heating-dominated structures as buildings scale up (which they will, since scale has cost advantages).


Vacuum Insulated panels can easily reduce heat loss to values close to 10 W/m2 in average Martian conditions of -75C and 25C interior.  For summer days, the outside temperature can be significantly higher than -75C, reducing heat transfer further to a few Watts per m2.  So although the heat storage capacity of structural elements in a Martian settlement are interesting, they may not be useful all that often during a typical year.
I would rather expect a Martian settlement to be surrounded by cooling radiators in a configuration similar to standard ground source horizontal heat pipes.

As I wrote, even if you're cooling-dominated it still makes sense to have heat storage, because it allows you to downsize your cooling system.


And to avoid freezing at the very low [ambient] temperatures, heat pumps may indeed be a good solution, as most circulating fluids may have freezing problems, circulating a gas might be a good alternative.  Operating pressure may be a problem?  Would be interesting to work out an arrangement.

For Mars I've been assuming supercritical CO2 for (typical, non-specialized) refrigeration loops. Cheap, plentiful, and efficient.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/02/2023 01:41 am
At -77C would ammonia with plate type heat exchangers by a likely solution for heat transfer fluid?
It would do away with the energy loss from refrigeration compression to use direct cooling.

Perhaps an ammonia exterior loop, with an internal water/glycol solution loop?  Arranged in such a way that when a pumps fails the heat exchanger goes to the water/glycol temperature rather than to the ammonia temperature?

Ammonia can be produced in situ, as can ethylene glycol.  Likely propylene glycol s well.

The water/glycol would circulate at standard cooling temperatures to condense out water from the food production and the respiration of the inhabitants.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/02/2023 01:59 am
According to at least one NASA engineer, ammonia probably will be avoided in the future due to the cost of mitigating toxic atmosphere risk.

https://www.quora.com/With-15-years-of-technological-advances-since-its-construction-how-would-the-International-Space-Station-differ-if-it-were-being-designed-now/answers/7656852

Quote
Many of the other changes are also "if we knew then what we know now" changes - so if ISS had not existed, we probably wouldn't fix for a new design. I think we would probably try to design the US/ESA/JAXA modules to use something other than ammonia in the external thermal control system. The ammonia never actually enters the vehicle, but it rubs up against the water lines that do go inside the vehicle. Heat from the water is conducted into the ammonia. There is a tiny possibility that a crack could form and ammonia could infiltrate the water and get inside the vehicle. Should that ammonia then get into the air, the crew could die. Because of that, we spend a lot of time training the crew to deal with an emergency toxic atmosphere scenario. The lifetime training costs for that will likely outweigh the added design costs of not using ammonia. The Russians do not use ammonia. They use polymethyl siloxane (anti-freeze). Although not something you want to drink, it is considerably less toxic (some fast food pizza chains use it in their cheese).
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/02/2023 02:19 am


For Mars I've been assuming supercritical CO2 for (typical, non-specialized) refrigeration loops. Cheap, plentiful, and efficient.
Isn't the operating pressure a little high?  Perhaps a liquid with a high specific heat might be more appropriate?
The high operating pressure is one of the things that kept CO2 in the 'real of nice but not practical' phase for the longest time...
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/02/2023 02:31 am


For Mars I've been assuming supercritical CO2 for (typical, non-specialized) refrigeration loops. Cheap, plentiful, and efficient.
Isn't the operating pressure a little high?  Perhaps a liquid with a high specific heat might be more appropriate?
The high operating pressure is one of the things that kept CO2 in the 'real of nice but not practical' phase for the longest time...

It does require higher pressures, but also smaller pipes because it's 5x as dense. Those two factors work in opposite directions, so it mostly comes out in the wash.

It's true that R744 took a while to get started, but nowadays there are many operational systems.

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/02/2023 03:28 am


For Mars I've been assuming supercritical CO2 for (typical, non-specialized) refrigeration loops. Cheap, plentiful, and efficient.
Isn't the operating pressure a little high?  Perhaps a liquid with a high specific heat might be more appropriate?
The high operating pressure is one of the things that kept CO2 in the 'real of nice but not practical' phase for the longest time...

It does require higher pressures, but also smaller pipes because it's 5x as dense. Those two factors work in opposite directions, so it mostly comes out in the wash.

It's true that R744 took a while to get started, but nowadays there are many operational systems.
Indeed, but R717 does have the advantage that it is stinky, so we can detect it :)
I understand the risk of ammonia on the ISS, since it is such a tiny volume and has little practical separation of that volume.  But if you keep the size of the ammonia loops and storage tanks under the safe volume for a habitat, or if you have the ammonia in a safe mechanical room vented to the outside, as we do today in many refrigeration plants and ice hockey rinks, I wonder if the danger is really significant, compared to many other thing that can go wrong on a Mars habitat. 
It's not like venting it to the outside will bother the local population.
And used as a liquid in an ammonia-water/glycol arrangement it has very high efficiency, requiring no phase change and no compression work.  As long as the water glycol solution is at a higher pressure than the ammonia, it should always leak in the right direction in the heat exchanger, i. e towards the ammonia.
And you will be making ammonia anyway for any number of needs.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/02/2023 03:30 am
...use a source that's less than a decade old, especially since there's been a lot of recent progress in this area.

https://electrek.co/2022/12/26/us-companies-are-producing-heat-pumps-that-work-below-20f/

Not air source, but ground source, very obviously.

Obviously. That changes nothing about what I wrote.

Ugly pestering from Twark_Main.

Play nice with the other kids.

Ignoring Martian subsurface temperatures, COP thermodynamics, and near-vacuum, too -- and giving no math, because it's just pestering.

...to avoid freezing at the very low ambiant temperatures, heat pumps may indeed be a good solution, as most circulating fluids may have freezing problems, circulating a gas might be a good alternative.

It's a thermodynamics problem, apart from fluid.  Plug Martian temperatures into Dumitrașcu et al. 2016, to see just how COP crashes when you deploy an ammonia ground-source heat pump on Mars.  Plot results.

And do you see any heat pumps in Antarctica?

Refs.

Dumitrașcu, G., Dumencu, A., Horbaniuc, B. and Atanasiu, M.V., 2016, August. Thermodynamic analysis of geothermal heat pump during the cold season. (https://iopscience.iop.org/article/10.1088/1757-899X/147/1/012137/pdf) In IOP Conference Series: Materials Science and Engineering (Vol. 147, No. 1, p. 012137). IOP Publishing.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/02/2023 04:34 am
[snip]

Play nice with the other kids.

Ignoring Martian subsurface temperatures

Already linked to the paper.

COP thermodynamics

Linked to that article too.

I'll let you dig up the exact charts. I understand that you couldn't before, since 24 hours ago you (apparently) didn't know that commercial heat pumps have made major progress in CoP recently.

and near-vacuum, too

Ground source not air source ("obviously").


...to avoid freezing at the very low ambiant temperatures, heat pumps may indeed be a good solution, as most circulating fluids may have freezing problems, circulating a gas might be a good alternative.

It's a thermodynamics problem, apart from fluid.  Plug Martian temperatures into Dumitrașcu et al. 2016, to see just how COP crashes when you deploy an ammonia ground-source heat pump on Mars.

Bad reading comprehension. Lamontagne said alternative to a heat pump, ie a single-phase coolant loop.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/02/2023 04:52 am
To try to avoid the talking past one another that has been going on here, I propose a little example.

Here is an 18m diameter 128m long metallic pressure vessel used as a Martian habitat.  It is insulated from the ground using 2 layers of vacuum insulated panel similar to the Panasonic AdvancR, so about R-120 or RSI 21. Heat loss is then 25--75/21 =  5 W/m2 on average.

The windows are double glazed with infrared reflecting film, perhaps R-2.  For nighttime, insulated exterior  curtains with a RSI or about 5 and a total of RSI of 7, so 15 W/m2 .  I'll guess for the moment that when the curtains are open the heat loss is about 50 W/m2, but should be partly offset by a significant heat gain from the sun.

More to come.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/02/2023 04:59 am
[snip]

Play nice with the other kids.

Ignoring Martian subsurface temperatures

Already linked to the paper.

COP thermodynamics

Linked to that article too.

I'll let you dig up the exact charts. I understand that you couldn't before, since 24 hours ago you (apparently) didn't know that commercial heat pumps have made major progress in CoP recently.

and near-vacuum, too

Ground source not air source. "Obviously."


...to avoid freezing at the very low ambiant temperatures, heat pumps may indeed be a good solution, as most circulating fluids may have freezing problems, circulating a gas might be a good alternative.

It's a thermodynamics problem, apart from fluid.  Plug Martian temperatures into Dumitrașcu et al. 2016, to see just how COP crashes when you deploy an ammonia ground-source heat pump on Mars.

Bad reading comprehension. Lamontagne said alternative to a heat pump, ie a single-phase ammonia coolant loop.

Oh, well, if you understand heat pump thermodynamics better than others, then you're the one to show how the heat pump of Dumitrașcu et al. 2016 (https://iopscience.iop.org/article/10.1088/1757-899X/147/1/012137/pdf) works on Mars. 

You can punch in temperatures and plot COP results.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/02/2023 05:02 am
Smart design for solar. From the looks you orient east-west, with the large window facing the southern/equatorial aspect.

Being a relatively small scale this example should almost certainly be heating-dominated, so this makes sense.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/02/2023 05:17 am
Smart design for solar. From the looks you orient east-west, with the large window facing the southern/equatorial aspect.

Being a relatively small scale this example should almost certainly be heating-dominated, so this makes sense.

lamontagne, for fun, insert Twark_Main's very novel dirt buffer (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2443734#msg2443734).  Ask him for numbers.
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/02/2023 10:17 pm
A little spreadsheet based on my tubular habitat.

As simple as I could make it.

As expected food production completely dominates.  However, when you turn the lights off, the heat loss becomes higher than the heat gain, so yes, I expect some form of thermal accumulation might be useful.

There is a section for heat storage in sand but it's not well thought out.  It should just store the heat for the night.
There is some phase change heat storage as well, but not in the correct range, I believe.  So more work needed.!
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/03/2023 04:54 pm
There is a section for heat storage in sand but it's not well thought out.  It should just store the heat for the night.
There is some phase change heat storage as well, but not in the correct range, I believe.  So more work needed.!

Here's an ESA Moon hab model.  Notice the use of regolith.

There's a very important difference here.  Do you see it?

Details in Section 5, Thermal Analysis.

Refs.

Akisheva, Y. and Gourinat, Y., 2021. Utilisation of Moon regolith for radiation protection and thermal insulation in permanent lunar habitats. (https://www.mdpi.com/2076-3417/11/9/3853/pdf?version=1619348366) Applied Sciences, 11(9), p.3853.
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/03/2023 07:06 pm

Here's an ESA Moon hab model.  Notice the use of regolith.

There's a very important difference here.  Do you see it?

Twark has his regolith inside the insulation while the paper has it outside?  And the paper is written for the Moon while we are looking at Mars.

Reading the paper, I dont quite see how you can compress regolith to 4 g/cm3 (page 12).  It seems like a theoretical result, because stone is generally in the 2-3g/cm3 range.  But that's a detail.

If we are producing food during the day, we would like to store some of the energy required for that to get through the night without requiring additional heating.  Not all that important if we are using nuclear reactors but useful if we are using mostly solar power.

For my example, the main heat loss during the night is through the walls, with a significant secondary loss through the windows.

The grow rooms are probably about 25C, while the living area something like 22C. The grow rooms can be cooled using water/glycol solutions in fan coil units, without the need for refrigeration as the exterior heat sink is significantly cooler than the grow rooms.  So there is no opportunity there for heat storage, as the coolant will probably be between 2 and 8 degrees C.

However, the night heat loss is not very high, at about 30 kW for the night hours.  Supposing the night is in winter and 16 hours long, then the heat loss is about 1700 MJ.

If the regolith covers most of the outside of the tube, even if only 1m thick, it will mass about 15 000 tonnes, and therefore over the night time will only cool by 0,1 degrees C.

So the regolith can buffer the overnight heat loss and make it barely noticeable by the inhabitants of the habitat.  However, there absolutely has to be very significant mechanical cooling during the day as the regolith will only absorb a tiny fraction of the heat load.

To be honest, I expect the thermal inertia of the regolith is such that, be it internal or external, the temperature of the settlement will be practically a constant and mainly influenced by the efficiency of the mechanical cooling.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/03/2023 08:29 pm

Here's an ESA Moon hab model.  Notice the use of regolith.

There's a very important difference here.  Do you see it?

Twark has his regolith inside the insulation while the paper has it outside?  And the paper is written for the Moon while we are looking at Mars.

Reading the paper, I dont quite see how you can compress regolith to 4 g/cm3 (page 12).  It seems like a theoretical result, because stone is generally in the 2-3g/cm3 range.  But that's a detail.

If we are producing food during the day, we would like to store some of the energy required for that to get through the night without requiring additional heating.  Not all that important if we are using nuclear reactors but useful if we are using mostly solar power.

For my example, the main heat loss during the night is through the walls, with a significant secondary loss through the windows.

The grow rooms are probably about 25C, while the living area something like 22C. The grow rooms can be cooled using water/glycol solutions in fan coil units, without the need for refrigeration as the exterior heat sink is significantly cooler than the grow rooms.  So there is no opportunity there for heat storage, as the coolant will probably be between 2 and 8 degrees C.

However, the night heat loss is not very high, at about 30 kW for the night hours.  Supposing the night is in winter and 16 hours long, then the heat loss is about 1700 MJ.

If the regolith covers most of the outside of the tube, even if only 1m thick, it will mass about 15 000 tonnes, and therefore over the night time will only cool by 0,1 degrees C.

So the regolith can buffer the overnight heat loss and make it barely noticeable by the inhabitants of the habitat.  However, there absolutely has to be very significant mechanical cooling during the day as the regolith will only absorb a tiny fraction of the heat load.

To be honest, I expect the thermal inertia of the regolith is such that, be it internal or external, the temperature of the settlement will be practically a constant and mainly influenced by the efficiency of the mechanical cooling.

Regolith is outside, yes; it doesn't waste hab space.  And it's separated by vacuum gap, cutting heat loss.

Use hab / greenhouse studies to build a plausible model.  E.g., greenhouse lighting isn't a pure heat gain; it's up to 100% PAR efficient (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949401/), hence well absorbed.

Any excess heat could be stored indefinitely in K2CO3 thermal batteries (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445518#msg2445518), outside.  Is 0.75 GJ/m3 the most compact indefinite storage feasible via ISRU?

Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/03/2023 09:38 pm

Regolith is outside, yes; it doesn't waste hab space.  And it's separated by vacuum gap, cutting heat loss.

Use hab / greenhouse studies to build a plausible model.  E.g., greenhouse lighting isn't a pure heat gain; it's up to 100% PAR efficient (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949401/), hence well absorbed.

Any excess heat could be stored indefinitely in K2CO3 thermal batteries (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445518#msg2445518), outside.  Is 0.75 GJ/m3 the most compact indefinite storage feasible via ISRU?
Most of the energy in a greenhouse goes to evapotranspiration, that is an essential physiological process required to circulate nutriments in the plant and, as far as I know, cannot be reduced without drastically reducing production, hence the heat loss from a green house has to be large, whatever the light source.  It's inherent to the biological process.  So in a greenhouse, of a grow room, the most important load is the latent load, not the sensible one.
I don't think there is much point in keeping excess heat beyond the normal heat loss of the habitat during the night.
The only alternative I can think of would be to use biological reactor to produce the food from methane, and that is well covered elsewhere on the site, and not quite there yet.

I'm not certain a greenhouse would really work well on Mars, compared to a grow room. 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/03/2023 09:57 pm
I don't think you would want to store solar energy directly as thermal energy on Mars, as in the paper you refer to. 
The habitat will probably be thermally positive in most cases, hence there will never be a need for heat storage beyond the inertia of the habitat.

The main available heat source will be cooling water from grow rooms (unless you can really produce all your food in greenhouses) you would need to use that low grade heat  at around 8°C, the temperature after condensing evaporated water.  As your rooms are at 20 to 25C there is no way to store that energy except perhaps using a heat pump.
You can keep a Martian habitat warm simply by using distributed grow rooms and transferred heat, and reducing the food production to a minimum in winter, just to maintain thermal equilibrium. 

I think Twain is adding thermal inertia to the habitat, but that may not be all that useful beyond a certain point, since vacuum insulated panels are so efficient, and Martian habitat construction seems well adapted to its use.  It also seems like a product that could be produced In Situ using foam glass and aluminum fairly soon in settlement development.
Title: Re: Envisioning Amazing Martian Habitats
Post by: InterestedEngineer on 01/03/2023 11:07 pm
Is it preferred to have active systems that can fail (heat pumps), or passive systems with few or no moving parts?

I think the latter, but is it possible?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 12:03 am

Regolith is outside, yes; it doesn't waste hab space.  And it's separated by vacuum gap, cutting heat loss.

Use hab / greenhouse studies to build a plausible model.  E.g., greenhouse lighting isn't a pure heat gain; it's up to 100% PAR efficient (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949401/), hence well absorbed.

Any excess heat could be stored indefinitely in K2CO3 thermal batteries (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445518#msg2445518), outside.  Is 0.75 GJ/m3 the most compact indefinite storage feasible via ISRU?

Most of the energy in a greenhouse goes to evapotranspiration, that is an essential physiological process required to circulate nutriments in the plant and, as far as I know, cannot be reduced without drastically reducing production, hence the heat loss from a green house has to be large, whatever the light source.  It's inherent to the biological process.  So in a greenhouse, of a grow room, the most important load is the latent load, not the sensible one.
I don't think there is much point in keeping excess heat beyond the normal heat loss of the habitat during the night.
The only alternative I can think of would be to use biological reactor to produce the food from methane, and that is well covered elsewhere on the site, and not quite there yet.

I'm not certain a greenhouse would really work well on Mars, compared to a grow room.

No, the internal phase change etc. is energy storage, not heat loss.  And unlike a terrestrial greenhouse, here the crop's light and heat inputs would be separated for efficiency:  e.g., PAR light from LED, heat from electrical heaters. 

You can run traclabs BioSim (https://traclabs.com/projects/biosim/) for some first numbers, e.g., power per unit biomass.
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 12:08 am
Twain is adding thermal inertia to the habitat, but that may not be all that useful beyond a certain point, since vacuum insulated panels are so efficient...

No engineer packs Mars hab walls with dirt, for reasons above.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 01:31 am
active systems that can fail (heat pumps)

They'd fail, yes, at the start.

In the studies of Meyer et al. 2011, Fairbanks set min ground temperature (~ -4 °C) for useful Alaskan ground source heat pumps (COP > 2).  No heat pumps were sunk into ground further north, e.g., at Barrow, due to the falling theoretical COP limit of colder ground sources.

Likewise, the winter heat pump sim of Dumitrașcu et al. 2016 has min COP on a freezing day with ground at ~ -3 °C.

Cf. ~ -45 °C at a Mars base.

Refs.

Dumitrașcu, G., Dumencu, A., Horbaniuc, B. and Atanasiu, M.V., 2016, August. Thermodynamic analysis of geothermal heat pump during the cold season. (https://iopscience.iop.org/article/10.1088/1757-899X/147/1/012137/pdf) In IOP Conference Series: Materials Science and Engineering (Vol. 147, No. 1, p. 012137). IOP Publishing.

Meyer, J., Pride, D., O’Toole, J., Craven, C. and Spencer, V., 2011. Ground source heat pumps in cold climates. (https://acep.uaf.edu/media/81851/Ground-Source-Heat-Pumps-in-Cold-Climates.pdf) Alaska Center for Energy and Power, Cold Climate Housing Research Center, Inc, 92.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 01:11 pm


Regolith is outside, yes; it doesn't waste hab space.

How many times do I have to say it?

The regolith is already there anyway for radiation shielding. It doesn't take up space in the hab (it's outside the pressure vessel), you just enlarge the thermal layer slightly (a few meters) so it encloses the surrounding rad shielding layer (roof overlay + walls)  too.

And it's separated by vacuum gap, cutting heat loss.

A simple vacuum gap isn't as good as real MLI. Essentially a vacuum gap is "zero layer insulation" with poor emissivity on either side (compared to shiny aluminized Kapton).
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 01:18 pm
Most of the energy in a greenhouse goes to evapotranspiration, that is an essential physiological process required to circulate nutriments in the plant and, as far as I know, cannot be reduced without drastically reducing production

Aquatic plants are much more productive. Kelp and/or algae.


I don't think there is much point in keeping excess heat beyond the normal heat loss of the habitat during the night.

Heat storage is bidirectional. It can also "store cold" to smooth out the cooling load. That's the point.

If your building requires any kind of heating or cooling, it can benefit from (exploiting the existing) thermal mass.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 01:41 pm
Just checking, but... posters do see why air-source heat pumps are n/a on Mars at any temperature, yes?  Fan in near-vacuum, yes?
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 01:54 pm
Twain is adding thermal inertia to the habitat, but that may not be all that useful beyond a certain point, since vacuum insulated panels are so efficient...

No engineer packs Mars hab walls with dirt, for reasons above.

I've seen plenty of buried hab designs. Did you think that regolith wasn't compacted (like any other earthworks)?


The problem comes when your buildings grow large. The roof is easy. But vertical walls* become insanely expensive if the entire mass of dirt must lie at the angle-of-repose. So instead you can use (more or less) standard mechanically stabilized earth techniques.

Don't think of it as "packing the walls with dirt."  You're really just surrounding the structure with a minimal retaining wall "shell."


Obviously this only works up to a finite height, and other techniques will be needed beyond a certain point. You might imagine switching to (costlier but lighter) water or polyethylene above a certain floor. So a typic stack-up might have a sloped section at the very bottom, then MSE, topped off by PE/H2O, then regolith on the roof.

Naturally this means that any section with a wall is more costly than an internal section which only needs to hold up the roof. So in general the scaling will favor tall buildings (many floors to maximize amortization of the roof shield) and wide buildings (low aspect ratio to maximize roof-to-wall ratio).




* vertical walls are of course not necessary, but step pyramids aren't well-optimized to maximize the number of floors below the roof; the other alternative is to build structures very close and conjoin the roof shielding "slabs" (which are dirt not concrete; I know that terminology slipped up some people before)
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 01:58 pm
active systems that can fail (heat pumps)

They'd fail, yes, at the start.

In the studies of Meyer et al. 2011, Fairbanks set min ground temperature (~ -4 °C) for useful Alaskan ground source heat pumps (COP > 2).  No heat pumps were sunk into ground further north, e.g., at Barrow, due to the falling theoretical COP limit of colder ground sources.

Likewise, the winter heat pump sim of Dumitrașcu et al. 2016 has min COP on a freezing day with ground at ~ -3 °C.

Cf. ~ -45 °C at a Mars base.

Refs.

Dumitrașcu, G., Dumencu, A., Horbaniuc, B. and Atanasiu, M.V., 2016, August. Thermodynamic analysis of geothermal heat pump during the cold season. (https://iopscience.iop.org/article/10.1088/1757-899X/147/1/012137/pdf) In IOP Conference Series: Materials Science and Engineering (Vol. 147, No. 1, p. 012137). IOP Publishing.

Meyer, J., Pride, D., O’Toole, J., Craven, C. and Spencer, V., 2011. Ground source heat pumps in cold climates. (https://acep.uaf.edu/media/81851/Ground-Source-Heat-Pumps-in-Cold-Climates.pdf) Alaska Center for Energy and Power, Cold Climate Housing Research Center, Inc, 92.

Still using outdated sources and temperatures for heat pumps, I see.


https://grist.org/housing/heat-pumps-do-work-in-the-cold-americans-just-dont-know-it-yet/

https://www.energy.gov/eere/buildings/residential-cold-climate-heat-pump-challenge

The heat pumps that get sent to Mars will be a generation or two beyond even current systems.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 02:15 pm

Regolith is outside, yes; it doesn't waste hab space.

How many times do I have to say it?

The regolith is already there anyway for radiation shielding. It doesn't take up space in the hab (it's outside the pressure vessel), you just enlarge the thermal layer slightly (a few meters) so it encloses the surrounding rad shielding layer (roof overlay + walls)  too.

No.  You loaded meters of dirt inside insulation panels, "inside the building envelope (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2443734#msg2443734)", pointlessly.  That cuts usable hab space.  Zero sum. 

And you're still ranting (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446191#msg2446191) about air-source heat pumps in near-vacuum.  In a spaceflight forum.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 02:20 pm

Regolith is outside, yes; it doesn't waste hab space.

How many times do I have to say it?

The regolith is already there anyway for radiation shielding. It doesn't take up space in the hab (it's outside the pressure vessel), you just enlarge the thermal layer slightly (a few meters) so it encloses the surrounding rad shielding layer (roof overlay + walls)  too.

No.  You loaded meters of dirt inside insulation panels, "inside the building envelope (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2443734#msg2443734)", pointlessly.

I mean the thermal envelope. Edited, so no-one else gets confused the same way.

That cuts usable hab space.  Zero sum

Yes, I suppose it's true that the total amount of space on Mars is finite.


And you're still ranting (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446191#msg2446191) about air-source heat pumps in near-vacuum.  In a spaceflight forum.

You're the only one who keeps bringing up the (silly) air-sourced idea.

Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 02:27 pm
And you're still ranting (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446191#msg2446191) about air-source heat pumps in near-vacuum.  In a spaceflight forum.

You're the only one who keeps bringing up the (silly) air-sourced idea.

No, you still maintain the obvious difference "changes nothing (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445566#msg2445566)" in your mind.  You have a string of ugly posts to correct there.
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 02:30 pm
And you're still ranting (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446191#msg2446191) about air-source heat pumps in near-vacuum.  In a spaceflight forum.

You're the only one who keeps bringing up the (silly) air-sourced idea.

No, you still maintain the obvious difference "changes nothing (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445566#msg2445566)" in your mind.  You have a string of ugly posts to correct there.

It "changes nothing about what I wrote" because I wasn't writing about air-sourced.  ::)
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 02:43 pm
And you're still ranting (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446191#msg2446191) about air-source heat pumps in near-vacuum.  In a spaceflight forum.

You're the only one who keeps bringing up the (silly) air-sourced idea.

No, you still maintain the obvious difference "changes nothing (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445566#msg2445566)" in your mind.  You have a string of ugly posts to correct there.

It "changes nothing about what I wrote" because I wasn't writing about air-sourced.  ::)

You actually ignored ground-source heat pump analyses, posting air-source stories.  How long will others play along, in a Mars thread?
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 02:52 pm
And you're still ranting (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446191#msg2446191) about air-source heat pumps in near-vacuum.  In a spaceflight forum.

You're the only one who keeps bringing up the (silly) air-sourced idea.

No, you still maintain the obvious difference "changes nothing (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445566#msg2445566)" in your mind.  You have a string of ugly posts to correct there.

It "changes nothing about what I wrote" because I wasn't writing about air-sourced.  ::)

You actually ignored ground-source heat pump analyses, posting air-source stories.  How long will others play along, in a Mars thread?

Imagine being so arrogant you think you know better than the speaker/writer what they themselves meant.

The thermodynamic cycle (including the temperature lift) is separate from the medium. It's true that right now (terrestrial) air-source units are the ones providing the motivation to push heat pump technology to lower and lower cold temperatures, but that's only because (terrestrial) ground source systems don't need to.

Nobody is proposing Martian air-source systems but you. Correct your own "string of ugly posts."
Title: Re: Envisioning Amazing Martian Habitats
Post by: Twark_Main on 01/04/2023 03:05 pm
A potentially interesting new technology:


https://www.pv-magazine.com/2023/01/02/residential-thermo-acoustic-heat-pump-produces-water-up-to-80-c/
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/04/2023 03:15 pm
Just checking, but... posters do see why air-source heat pumps are n/a on Mars at any temperature, yes?  Fan in near-vacuum, yes?
Fan in near-vacuum works. Not only works, but works well enough for vertical powered flight. That’s what Ingenuity can fly.

Also, calling Mars a near-vacuum is sort of a misnomer. Sound travels, helicopters can fly (as could winged aircraft), heat can convect, you can even extract water vapor and (of course) CO2. At Mars’ Hellas Basin on a cold day, it’s about 7-10% of the density at Mount Everest (which people can, at great danger and with lots of training, climb without supplemental oxygen).

I think the issue is that an air source heat pump wouldn’t work very efficiently given the very cold Martian ambient temperature.

Solar heating plus insulation (including potentially closing exterior window shades at night) and thermal mass are a better bet IMHO.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 03:45 pm
Just checking, but... posters do see why air-source heat pumps are n/a on Mars at any temperature, yes?  Fan in near-vacuum, yes?
Fan in near-vacuum works. Not only works, but works well enough for vertical powered flight. That’s what Ingenuity can fly.

Also, calling Mars a near-vacuum is sort of a misnomer. Sound travels, helicopters can fly (as could winged aircraft), heat can convect, you can even extract water vapor and (of course) CO2. At Mars’ Hellas Basin on a cold day, it’s about 7-10% of the density at Mount Everest (which people can, at great danger and with lots of training, climb without supplemental oxygen).

I think the issue is that an air source heat pump wouldn’t work very efficiently given the very cold Martian ambient temperature.

Solar heating plus insulation (including potentially closing exterior window shades at night) and thermal mass are a better bet IMHO.

No, a fan can't give the heat pump's required mass flow there.  No one really argues otherwise.

Re ground temperature, a heat pump with COP < 2 is useless.  What's the min useful temperature (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446070#msg2446070)?
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 06:34 pm
Title: Re: Envisioning Amazing Martian Habitats
Post by: Oersted on 01/04/2023 07:26 pm
The LMT >< TwarkMain feuding in this thread is getting extremely tiresome. You guys are ruining a great thread. You have been told very many times to knock it off. What can be done now to make it stop??
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 07:46 pm
The LMT >< TwarkMain feuding in this thread is getting extremely tiresome. You guys are ruining a great thread. You have been told very many times to knock it off. What can be done now to make it stop??

I still think NSF should give little prizes for topical challenges, to encourage collaboration, etc.

What are some relevant quantitative challenges in thread today?
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/04/2023 08:59 pm
The LMT >< TwarkMain feuding in this thread is getting extremely tiresome. You guys are ruining a great thread. You have been told very many times to knock it off. What can be done now to make it stop??

I still think NSF should give little prizes for topical challenges, to encourage collaboration, etc.

What are some relevant quantitative challenges in thread today?
-A quantitative value for total power Watts/m2 for grow rooms, with the corresponding crop yield.
-A simple design comparaison of a Mars fluid cooler using low density Martian air vs a horizontal geothermal cooling field vs radiative cooling panels.



Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/04/2023 09:06 pm
Is it preferred to have active systems that can fail (heat pumps), or passive systems with few or no moving parts?

I think the latter, but is it possible?
It seems difficult to handle the energy from greenhouses or grow rooms with purely passive systems due to the extreme temperature variations.
A cooling loop vs a refrigeration loop will always require less energy and maintenance.  However, a compressor is only an extreme version of a pump, so redundancy and maintenance can probably make the two similar.  Pressure should be lower in cooling loops than refrigeration loops.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/04/2023 10:31 pm
-A quantitative value for total power Watts/m2 for grow rooms, with the corresponding crop yield.

BioSim (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446058#msg2446058) references JSC Advanced Life Support numbers for biomass power, possibly Hanford 2004, Hanford 2006.

BioSim grows wheat.  You might check BioSim biomass etc. against my simple extrapolation of the record wheat yield of Bugbee and Salisbury (https://forum.nasaspaceflight.com/index.php?topic=35877.msg2319400#msg2319400):  ~ 15 m2 / ~ 33 m3 of wheat plot per person (3000 cal/day). 

Refs.

Hanford, A.J., 2004. Advanced Life Support Research and Technology Development Metric (No. S-940). (https://ntrs.nasa.gov/api/citations/20040139875/downloads/20040139875.pdf)

Hanford, A.J., 2006. Subsystem Details for the Fiscal Year 2004 Advanced Life Support Research and Technology Development Metric. (https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1001&context=nasatr)
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/04/2023 11:37 pm

Regolith is outside, yes; it doesn't waste hab space.  And it's separated by vacuum gap, cutting heat loss.

Use hab / greenhouse studies to build a plausible model.  E.g., greenhouse lighting isn't a pure heat gain; it's up to 100% PAR efficient (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949401/), hence well absorbed.

Any excess heat could be stored indefinitely in K2CO3 thermal batteries (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2445518#msg2445518), outside.  Is 0.75 GJ/m3 the most compact indefinite storage feasible via ISRU?

Most of the energy in a greenhouse goes to evapotranspiration, that is an essential physiological process required to circulate nutriments in the plant and, as far as I know, cannot be reduced without drastically reducing production, hence the heat loss from a green house has to be large, whatever the light source.  It's inherent to the biological process.  So in a greenhouse, of a grow room, the most important load is the latent load, not the sensible one.
I don't think there is much point in keeping excess heat beyond the normal heat loss of the habitat during the night.
The only alternative I can think of would be to use biological reactor to produce the food from methane, and that is well covered elsewhere on the site, and not quite there yet.

I'm not certain a greenhouse would really work well on Mars, compared to a grow room.

No, the internal phase change etc. is energy storage, not heat loss.  And unlike a terrestrial greenhouse, here the crop light and heat inputs would be separated for efficiency:  e.g., PAR light from LED, heat from electrical heaters. 

You can run traclabs BioSim (https://traclabs.com/projects/biosim/) for some first numbers, e.g., power per unit biomass.
I don't have a apache server, that seems to be required to run Biosim.  So can't install the software.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/05/2023 12:06 am
I don't have a apache server, that seems to be required to run Biosim.  So can't install the software.

Well, if you need Apache, you can install Apache.  BioSim Java code was tested on Windows, Linux, and Mac.

Simple BioSim installation steps here (http://daneel.traclabs.com/biosim/download.html).

The app has a nice interface.
 
Title: Re: Envisioning Amazing Martian Habitats
Post by: Robotbeat on 01/05/2023 01:01 am
Just checking, but... posters do see why air-source heat pumps are n/a on Mars at any temperature, yes?  Fan in near-vacuum, yes?
Fan in near-vacuum works. Not only works, but works well enough for vertical powered flight. That’s what Ingenuity can fly.

Also, calling Mars a near-vacuum is sort of a misnomer. Sound travels, helicopters can fly (as could winged aircraft), heat can convect, you can even extract water vapor and (of course) CO2. At Mars’ Hellas Basin on a cold day, it’s about 7-10% of the density at Mount Everest (which people can, at great danger and with lots of training, climb without supplemental oxygen).

I think the issue is that an air source heat pump wouldn’t work very efficiently given the very cold Martian ambient temperature.

Solar heating plus insulation (including potentially closing exterior window shades at night) and thermal mass are a better bet IMHO.

No, a fan can't give the heat pump's required mass flow there.  No one really argues otherwise.

Re ground temperature, a heat pump with COP < 2 is useless.  What's the min useful temperature (https://forum.nasaspaceflight.com/index.php?topic=41427.msg2446070#msg2446070)?
It actually can. But you need a big fan and a big heat exchanger.

And anything with a COP greater than 1 is better than resistive heating from an energy standpoint.

If we’re talking about heat REJECTION of the excess heat of the greenhouse instead of heat PUMPING, we could actually recover some electricity because the greenhouse ambient temperature is higher than the outside ambient temperature. Whether that’s worth doing or not is another story…
Title: Re: Envisioning Amazing Martian Habitats
Post by: lamontagne on 01/05/2023 02:26 am
I don't have a apache server, that seems to be required to run Biosim.  So can't install the software.

Well, if you need Apache, you can install Apache.  BioSim Java code was tested on Windows, Linux, and Mac.

Simple BioSim installation steps.

The app has a nice interface.

I'm sorry but that's a weak point in my education, I can't do the installation.
So I will go for an analog instead, using the nice information provided by these people about their containerized food production system.  I'm finding about 250 W/m2 for 67 kg/m2 food production.

https://www.freightfarms.com/greenery-s#s-booklet

I would greatly appreciate if you could verify their numbers using the Sim.
Title: Re: Envisioning Amazing Martian Habitats
Post by: LMT on 01/05/2023 04:48 am
I'm sorry but that's a weak point in my education, I can't do the installation.
So I will go for an analog instead, using the nice information provided by these people about their containerized food production system.  I'm finding about 250 W/m2 for 67 kg/m2 food production.

https://www.freightfarms.com/greenery-s#s-booklet

I would greatly appreciate if you could verify their numbers using the Sim.

To raise interest, don't aim merely to replicate reference tables published decades ago.  Look for hab game-changers, and break the mold; that might draw multiple collaborators.