Author Topic: Envisioning Amazing Martian Habitats  (Read 869957 times)

Offline meekGee

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Re: Envisioning Amazing Martian Habitats
« Reply #1460 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...
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Offline Paul451

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Re: Envisioning Amazing Martian Habitats
« Reply #1461 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.]
« Last Edit: 01/22/2018 09:06 am by Paul451 »

Offline jpo234

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Re: Envisioning Amazing Martian Habitats
« Reply #1462 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
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Online Oersted

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Re: Envisioning Amazing Martian Habitats
« Reply #1463 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?

Offline Paul451

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Re: Envisioning Amazing Martian Habitats
« Reply #1464 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.

Offline aero

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Re: Envisioning Amazing Martian Habitats
« Reply #1465 on: 02/12/2018 04:20 pm »
Multiple levels of concentric rings. Expanding the habitat rings in three dimensions keeps everything close. (relatively)
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Online Oersted

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Re: Envisioning Amazing Martian Habitats
« Reply #1466 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!     

Offline Semmel

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Re: Envisioning Amazing Martian Habitats
« Reply #1467 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.

Offline guckyfan

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Re: Envisioning Amazing Martian Habitats
« Reply #1468 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.

Online Oersted

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Re: Envisioning Amazing Martian Habitats
« Reply #1469 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? 

Offline Valerij

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Re: Envisioning Amazing Martian Habitats
« Reply #1470 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)
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.

Offline Jim Davis

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Re: Envisioning Amazing Martian Habitats
« Reply #1471 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".

Offline speedevil

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Re: Envisioning Amazing Martian Habitats
« Reply #1472 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.
« Last Edit: 02/13/2018 04:59 pm by speedevil »

Offline Jim Davis

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Re: Envisioning Amazing Martian Habitats
« Reply #1473 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.


Offline Lar

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Re: Envisioning Amazing Martian Habitats
« Reply #1474 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.


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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.
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Offline speedevil

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Re: Envisioning Amazing Martian Habitats
« Reply #1475 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.


What forms of art might lend themselves to actually being performed on the minimally improved surface?

Offline LMT

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Re: Envisioning Amazing Martian Habitats
« Reply #1476 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 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.




« Last Edit: 03/09/2018 03:21 pm by LMT »

Offline speedevil

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Re: Envisioning Amazing Martian Habitats
« Reply #1477 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 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.


Offline alexterrell

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Re: Envisioning Amazing Martian Habitats
« Reply #1478 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).

Offline LMT

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Re: Envisioning Amazing Martian Habitats
« Reply #1479 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 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.



And ReBCO tape does continue to improve.  Improvements in critical current density are slashing the mass requirement, which in turn has led us to consider a lightweight cable design modeled after the ENEA-TRATOS design.



The advantage of such a lightweight cable is that its self-generated Lorentz forces can self-deploy an Omaha Field, 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.

« Last Edit: 03/09/2018 07:11 pm by LMT »

 

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