Author Topic: Envisioning Amazing Martian Habitats  (Read 868125 times)

Offline Lumina

Re: Envisioning Amazing Martian Habitats
« Reply #1440 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?

Offline Ludus

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Re: Envisioning Amazing Martian Habitats
« Reply #1441 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.

Offline Ludus

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Re: Envisioning Amazing Martian Habitats
« Reply #1442 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.

Offline Lumina

Re: Envisioning Amazing Martian Habitats
« Reply #1443 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) 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.
« Last Edit: 01/14/2018 06:13 pm by Lumina »

Offline blasphemer

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Re: Envisioning Amazing Martian Habitats
« Reply #1444 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)

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..

Offline TripD

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Re: Envisioning Amazing Martian Habitats
« Reply #1445 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.

Offline Robotbeat

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Re: Envisioning Amazing Martian Habitats
« Reply #1446 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.
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Offline Robotbeat

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Re: Envisioning Amazing Martian Habitats
« Reply #1447 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)

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.
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Offline Oersted

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Re: Envisioning Amazing Martian Habitats
« Reply #1448 on: 01/14/2018 10:56 pm »
Well said.  Or as Gwynne said at Stanford:
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.

Offline meekGee

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Re: Envisioning Amazing Martian Habitats
« Reply #1449 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?
« Last Edit: 01/15/2018 02:40 am by meekGee »
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Offline speedevil

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Re: Envisioning Amazing Martian Habitats
« Reply #1450 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.

Offline guckyfan

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Re: Envisioning Amazing Martian Habitats
« Reply #1451 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.

Offline meekGee

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Re: Envisioning Amazing Martian Habitats
« Reply #1452 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.


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Offline Robotbeat

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Re: Envisioning Amazing Martian Habitats
« Reply #1453 on: 01/15/2018 03:51 am »
Well said.  Or as Gwynne said at Stanford:
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.
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Offline Paul451

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Re: Envisioning Amazing Martian Habitats
« Reply #1454 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.

Offline meekGee

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Re: Envisioning Amazing Martian Habitats
« Reply #1455 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
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Offline Lar

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Re: Envisioning Amazing Martian Habitats
« Reply #1456 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...
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Offline Robotbeat

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Re: Envisioning Amazing Martian Habitats
« Reply #1457 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/
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Offline Lar

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Re: Envisioning Amazing Martian Habitats
« Reply #1458 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...
« Last Edit: 01/19/2018 04:41 am by Lar »
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Offline KelvinZero

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Re: Envisioning Amazing Martian Habitats
« Reply #1459 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.


 

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