settling in craters - roofed by geodesic sphere

dickbill · 2004-02-05 17:14:02

Of course the moon might make a better test bed for Mars than Mt. Everest, but I could be wrong.

As you said Clark, the Moon "might" be better for that particular aspect of martian technology (I don't think so but we can discuss). But what is sure is that the Moon will be more expensive, as said Bill White:

Cheaper than the moon and easier to get tourists to and from

and FASTER too. We wouldn't wait 20 years to test a biodome on the Moon, just to constate that it wouldn't work on Mars.

dickbill · 2004-02-06 09:03:35

I found a reference:
[http://news.nationalgeographic.com/news … overs.html]http://news.nationalgeographic.com/news....rs.html

So at 6000 m, the UV radiation is 48% higher than sea level. I wished it was more, to fit better with today's Mars but at least we can expect a stronger UV radiation on a 8K summit.
The Himmalayan Everest is actually not a great spot, it's too humid (in term of snow received, not rain) due to its low latitude and exposure to the Monsoon. In a drier place or higher latitude, a 8K summit would fit even better to the Martian conditions, the pressure would be lower than 300mb, it would be much drier and much colder. A 8K summit in Antarctica would really be like Mars on Earth. Unfortunatly, with a pityfull 4897 m highest summit in Antarctica, Mt Everest still fits better with Martian conditions.

[http://7summits.com/vinson/vinson.htm]http://7summits.com/vinson/vinson.htm

Shaun Barrett · 2004-02-06 20:18:59

I think I read somewhere that people are trying to clean up places like Everest, where years of expeditions have left tonnes of garbage lying around(?).
In addition, of course, many of the indigenous people in neighbouring regions regard Everest as a sacred place, or even a divine being.

In either case, or both cases, wouldn't it be difficult to get permission to set up a sizeable pressurised 'base' at the summit, requiring strong foundations buried in the rock to stabilise it against the fierce winds, a base constantly visited and observed by teams of scientists coming and going?
There's also the problem of how to get building materials, crew and visiting observers to the peak. Ordinary heavy-lift helicopters don't fly to altitudes of 8.8 km.
But, having said that, I do acknowledge that the problems associated with building a Moon-base make a base on Everest relatively straightforward!

[P.S. Just to clarify my position again, I don't see the Moon as a sensible testing ground for human Mars missions because the conditions are quite different there. And the idea of launching a Mars mission from Luna just doesn't make sense in terms of delta-v. I'm informed by those much wiser than I that there are other places we could launch from (in space) which are much more economical in terms of rocket fuel.
The existence of water ice in shadowed polar craters on the Moon is yet to be demonstrated beyond doubt. Even if it's there, how much mining infrastructure would have to be sent to the Moon's south pole before we could access it? How long would it take to build up the infrastructure? Etc. etc. etc.
By all means have your outpost on the Moon, but don't make crewed missions to Mars conditional upon it! ]

dickbill · 2004-02-06 22:58:01

I think I read somewhere that people are trying to clean up places like Everest, where years of expeditions have left tonnes of garbage lying around(?).

that's a problem very well known now. It needs cleaning. Also when I say a 8K summit, I don't necesseraly means the Everest, there are others 8000' in the Himalayan.

In addition, of course, many of the indigenous people in neighbouring regions regard Everest as a sacred place, or even a divine being.

Well, that's for a noble cause. Maybe these indegenous population would like the idea to be associated with a great space adventure.

In either case, or both cases, wouldn't it be difficult to get permission to set up a sizeable pressurised 'base' at the summit, requiring strong foundations buried in the rock to stabilise it against the fierce winds, a base constantly visited and observed by teams of scientists coming and going?

I think it depends about the size of the biosphere that you have in mind. The point of the experiment would be only to test the materials, kevlar or other, that make the dome and its plastic membranes, resistance to the cold (-60C recorded on Mt Everest), resistance of the dome to the low pressure : in the ambiant 300mb Everest pressure, possibly 700mb of positive pressure must be contained if the dome is pressurized at 1 atm, which would be about the same pressure that the dome would have to sustain on Mars and resistance to the UV radiation on that dome. The dome would be pressurized by a small compressor wich would mimic the CO2 compressor that would work on Mars, and some plants would be added inside the dome to test their resistance to the UV in the long term, and how the dome cycle properly in the long term with these plants. But all together, it could be a small 10 meters diameter dome .
It would be light enough to be carried by an alpinist expedition.

The existence of water ice in shadowed polar craters on the Moon is yet to be demonstrated beyond doubt. Even if it's there, how much mining infrastructure would have to be sent to the Moon's south pole before we could access it? How long would it take to build up the infrastructure? Etc. etc. etc.
By all means have your outpost on the Moon, but don't make crewed missions to Mars conditional upon it! ]

You are right Shaun, I also read recently that scientist now doubt there is any ice in the moon.
What a bad surprise if a base 'must' be installed there and there is no water available. And anyway the 'Bush' concept is foolish : if the moon base failed/is more expensive than anticipated/is longer to set up, does that mean the Mars expedition is posponed ?
the answer is yes if you consider the moon as a testbed. So the moon-base must be installed there at all cost before we can venture to Mars ? Otherwise people will think that if we cannot do it on the Moon, we cannot do it on Mars ? dangerous strategy.

We know on this board that Mars conditions, OK, they are rough, they are bad, it's far etc. It's not for the faint of heart. But the Moon ! it's the vacuum, it's like the ISS, maybe worse actually. A base on the moon will just be like an ISS segment : a pressurized metallic can but buried under the lunar regolith.
A base on Mars : we talk about biodomes and vegetals growing inside, it's almost architecture and gardening together. It's the Eden garden reinvented.

Shaun Barrett · 2004-02-07 01:42:28

Ah, now I understand your high altitude experiment better and I agree with you that it could be achieved. And I like it much better than the idea of testing hardware on the Moon!

And I also agree with your logic about all the things which could go wrong on the Moon. If, as you point out, all our hopes for humans-to-Mars are made conditional upon the establishment of a successful lunar outpost, it's a precarious situation for Marsophiles!
We might have to wait forever.

Byron · 2004-02-07 07:28:21

I have an idea, Dickbill for your experiment. Instead of going to the trouble of doing all of this on Everest (which could be done, but it'd be risky for the people involved, etc), why not do this in Antarctica? It's not as high as Everest (although parts of the ice cap are over 12,000 feet I believe) and it's plenty darned cold, to boot.

Does it matter what the actual air pressure inside the kevlar dome and the outside as long is, as long as the pressure differential is the same as it would be on Mars? (Just take the current outside air pressure and pump up the dome so that it's 350 millibars more.) As for radiation exposure, couldn't that be carried out in the lab or by way of using computer models? I do know that Antarctica gets a lot more UV radiation than most places on Earth, just perhaps not as much as Everest.

I should say that I'm probably swayed by KSR's writings, as he uses Antarctica as a training ground for his 100 Martian settlers, but to me, it makes perfect sense, especially since we already have the infrastructure down there to carry out these types of experiments, etc...

B

dickbill · 2004-02-07 11:42:21

I have an idea, Dickbill for your experiment. Instead of going to the trouble of doing all of this on Everest (which could be done, but it'd be risky for the people involved, etc), why not do this in Antarctica? It's not as high as Everest (although parts of the ice cap are over 12,000 feet I believe) and it's plenty darned cold, to boot.

I am not an expert but I think that now, going to the Everest or Antarctica is not as risky as in the past.They are almost playgraund for a subset of tough adventurier/destination.
So, Antarctica/Everest : which is the easyiest/most affordable I don't know.
Mt Kinley in the US has a 500mb pressure on the submit it could also be a possible target.

Actually, there is a way to mimic even better the martian conditions, that's with a stratospheric hydrogen balloon. I don't know how much they can carry. Probably a minidome could be manufactured in the range of the hundreds of kilogram, with a mini heater, a small compressor, UV sensors, some basic plants (this is very important I think to embark plants, maybe some small animals), a camera/webcam, and it would be left to the derive for several weeks.
This 'test dome' could even include a visible light coat to shield the visible light by 50/60%, to mimic better Mars.

But a station on top of a montain has the merit to be quasi permanent and there is no real restriction of size. It could be a real size dome. Plus, there is the fun of the alpine expedition.

Does it matter what the actual air pressure inside the kevlar dome and the outside as long is, as long as the pressure differential is the same as it would be on Mars? (Just take the current outside air pressure and pump up the dome so that it's 350 millibars more.)

you are right, it doesn't really matter. But In other discussions related to that problem, I didn't see much agreement. Some want a weakly pressurized dome rich in oxygen, other prefer a higher pressure with less oxygen. I guess 300mb is the minimun positive pressure that a dome has to sustain with O2 rich air, but personnaly I don't like the idea to live in an oxygen-rich atmosphere.

Also, Earthfirst made a comment about BiosphereII, he said that the reason that CO2 accumulated in the dome was the O2 consumption by all the biomass, so maybe that means that we need 2 kinds of domes on Mars, one to produce food and O2 and another one to live inside. So all domes on Mars might not be all alike.

RobS · 2004-02-07 11:59:41

The exterior temperature on adome built on Earth does not have to be as low as on Mars because the Earth's denser atmosphere is more efficient at cooling. Its more powerful winds would require a much heavier dome, too. And Antarctica's six months of darkness would be a big barrier to agriculture. Why not just build the dome in Colorado at 14,000 feet? Transportation would be easier.

The moon would be a lousy place to build a Mars analogy greenhouse because of the 2-week nights and the micrometeoroids.

As for harvesting lunar polar ice, we will make sure it is there first! The new plan calls for robotic reconnaisance of the moon starting in 2008. The poles will receive most of that attention, ihncluding landers.

Ice harvester equipment has been designed; it's on the Colorado School of Mines website (Google Michael Duke to find it). It masses around six or eight tonnes, including a 1-tonne nuclear reactor, a 2-tonne oven, a scooper, radiators, and electrolysis equipment. The analysis assumed loose regolith with 2% ice (not enough to freeze the stuff hard as rock, and in the range most people expect). The harvester, if I remember right, was projected to be able to harvest its own mass in water per month.

Shaun Barrett · 2004-02-07 18:49:19

In response to Dickbill's comment about a perceived lack of agreement on the pressure and composition of artificial atmospheres in space, I was getting the impression that a practical consensus was emerging.
An atmosphere of 350 millibars (~5 lbs/sq. in.), with 210 millibars of O2 (~3 lbs/sq. in.) and 140 millibars of N2 (~2 lbs/sq.in.) seemed to be popular.
If I remember correctly, someone said this was the atmosphere used aboard Skylab and it worked well enough.
Evidently, at that sort of pressure, with that concentration of inert nitrogen, spontaneous fires aren't a problem and it obviously satisfies human physiological requirements. Such a low pressure makes engineering a little easier too.
I suspect this kind of air will become the standard on Mars; both inside habs and domes to begin with and, hopefully, on a planetary scale in the long run.

dickbill · 2004-02-09 12:38:25

An atmosphere of 350 millibars (~5 lbs/sq. in.), with 210 millibars of O2 (~3 lbs/sq. in.) and 140 millibars of N2 (~2 lbs/sq.in.) seemed to be popular.
If I remember correctly, someone said this was the atmosphere used aboard Skylab and it worked well enough.
Evidently, at that sort of pressure, with that concentration of inert nitrogen, spontaneous fires aren't a problem and it obviously satisfies human physiological requirements. Such a low pressure makes engineering a little easier too.

Shaun, when you go into details, everything seems more complex. Ok, that low pressure is fine aboard a space station, and you are right to say that it could be used for human living quaters, but then, this is not exactly a biosphere.

We don't know if such ratio of O2/N2 (or maybe argon in Mars) and CO2 (that you omit but that we should consider if we want a biosphere with plants) is stable at 350 mb on a long term, stabilized atmosphere in equilibrium with all the occupants, animal and plants, in the small partially enclosed ecosystem.
That's the point to study such small ecosystem on earth, in conditions as close as possible as the conditions that we think we gonna have on mars.
For a first test, we may very well start with a dome on top of a 6000 m or more submit on earth with the pressure and gaz ratio that you indicate but after 6 months the system evolutes by itself to reach an equilibrium, which might be unsuitable for human life.

And domes for plant and human life might even be incompatible. It would be nice if vegetal domes were truely in equilibrium, with just some Mars atmosphere added from time to time, while food producing domes and human recreative dome could be partially repleted with O2 and maintained in an out of equilibrium state.
I have visited the biodome at Montreal several times, the idea to have different ecosystem (tropical, arctic) side by side is nice, however, one day, I saw the reconstituted arctic sea with salmons in poor shape inside. Obviously the ecosystem was collapsing.
That arctic pool was big, gigantic, but not big enough to sustain all its occupants obviously. What caused that collapse I don't know. Sometimes tiny details matter. I mentioned the porous concrete in BiosphereII, which unexpectidly left some gas filter in an out the concrete that eventually poisonned the biosphereII atmosphere with CO2, Earthfirst mentioned the content in microorganisms etc. For the artic pool in the Montreal biodome it could have been the seabirds that were freely allowed to defecate in the pool (I always found that dangerous).
I would say there is a butterfly effect here.
If you are an aquarist hobbyist, you know that rule, the bigger the tank, the slower it reacts but the more stable it is on the long term, and that stable state can be quiet different from what you expect, depending of a multitude of parameters.

Shaun Barrett · 2004-02-09 19:36:03

Sorry, I wasn't thinking of something as complex as a self-sustaining biosphere. And I certainly haven't the expertise to make any sensible comments about the evolution of such an atmosphere over time.
All I was doing was pointing out that, at least temporarily, and with constant 'external' adjustments to maintain it, the kind of atmosphere I mentioned should be acceptable to dome-dwellers on Mars.
I'm sure you are right that a self-sustaining atmosphere is an entirely different proposition.

dickbill · 2004-02-10 07:33:34

Sorry, I wasn't thinking of something as complex as a self-sustaining biosphere. And I certainly haven't the expertise to make any sensible comments about the evolution of such an atmosphere over time.
All I was doing was pointing out that, at least temporarily, and with constant 'external' adjustments to maintain it, the kind of atmosphere I mentioned should be acceptable to dome-dwellers on Mars.
I'm sure you are right that a self-sustaining atmosphere is an entirely different proposition.

First of all, I think there is a confusion between the situations that we forecast.
1) if we talk about a first mission in the spirit of "mars direct', with a Hab on Mars, then the issue of an atmosphere such as the one I was talking about is irrelevant. In the HAb, Shaun is right to say that a Skylab-like atmosphere could be suitable.

2) after several Habs are installed, at the second or third mission of that type, I think it'ds gonna be time to install a small biodome. Now, what's gonna be the purpose of that dome should be specified. It could be recreative, vegetal, green house, selfsufficient or not etc.

3) Other scenarios are possible but in any case I don't think that a self sufficient biodome, with an autoregenerative atmosphere by O2producing plants can be installed in a first mission. It would need to be huge. BiospehereII failded to function autosufficiently, what is a problem of size ? probably not only, but size, by the buffering capabilities that it provides, is the most important factor. There is a threshold and we don't know where it is.
In any case that issue shouldn't be the main issue for the crew of a first exploration mission.

4) small domes could be tested however, in that mission. Like a green house using compressed martian air, mostly CO2 and repleted with chemically produced O2 to allow people to enter the green house. The atmosphere could be maintained that way. But the crew of that first mission should not depend on it, neither for O2 or food, it could just be a nice supplement.

But I have a question now, In the hypothesis that a big dome is installed on Mars, wouln't it be interesting to put plants in it ? and still be able to breath, how good is the skylab atmosphere for that ? 350mb, with 210mb O2, 140 mb N2 ?

MarsDog · 2004-04-02 04:14:13

Forget the domes, safety and ease is with the caves.
Just add light collectors and "light pipes"
-
Already the Mars Rovers are drilling;
Bigger Rovers and drills to make bigger holes.

chat · 2004-04-10 19:25:46

I don't want to throw everyone of the general topic on this, but what the heck. *lol*

Wouldn't one of those blow up tennis courts be easier to use on mars?
With no leaks of course.

On mars take advantage of the dust storms, and instead of making a tennis court that repels dirt, it collects in on the roof.
The bottom 6 feet or so can be made of glass or thick plastic material to allow light in, but little other radiation.

Instant structure, with wind assisted radiation shield.
Blowing it up in a crater is a good idea though.
In fact blowing it up on the lowest elevation of mars makes even more sense.
Less radiation, warmer and more pressure lower down.

1 compressor, 1 easy pack blow up shelter and a dust storm or two.
If the dust storms don't cooperate with your dirt shield, then use the compressor to pump dust up on the roof.

Packing that for mars makes sence.

Materials? whatever the mars chemistry does not try to destroy.

MarsDog · 2004-04-12 00:47:22

Large structures, even if gas inflated, take a lot of resources. Creating a biodome from a small crater might be the second
phase. The initial safety concerns are best answered by cave development.
-
The inside of a carter is a shield from the wind, and the sunlit side a convenient support fort light collection panels. Directing
sunlight to the cave entrances, the light collection panels could supply power and illumination needs.
A large crater, with multiple caves, might be the most productive option to start a manufacturing base.

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Re: settling in craters - roofed by geodesic sphere

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