Clearly you'd need "synthetic limestone"
Quote from: Lar on 05/11/2016 03:00 amClearly you'd need "synthetic limestone"I don't know how you would concentrate the calcium. I'm not sure how much calcium is in Mars regolith. On Earth, you get it from limestone, beds of shells and bones that have not yet compacted to sedimentary rock, and you can distill it from well water. Even if there is as much on Mars as on Earth, the mechanisms to concentrate it would be difficult at best. I am not sure what else could sat as a binder. This doesn't even consider the hardness and purity necessary in the sand and gravel aggregate.
We've seen gypsum in veins, that's calcium sulfate. If we find enough of it, maybe we can make a plaster.
Interesting for the modular, movable construction.
Quote from: CuddlyRocket on 05/12/2016 01:56 amInteresting for the modular, movable construction.I am surprised at the elevated pods. This leaves the underside exposed, increasing the amount of surface area exposed to radiant x convective thermal loss. Putting it on the surface with closed cell foam insulation under the bottom and sides that aerodynamically deflect convective winds would be much more efficient in such a cold environment.
Quote from: TomH on 05/12/2016 05:44 pmQuote from: CuddlyRocket on 05/12/2016 01:56 amInteresting for the modular, movable construction.I am surprised at the elevated pods. This leaves the underside exposed, increasing the amount of surface area exposed to radiant x convective thermal loss. Putting it on the surface with closed cell foam insulation under the bottom and sides that aerodynamically deflect convective winds would be much more efficient in such a cold environment.However the downside is that escaping heat causes the ice below to melt which causes uneven subsiding leading to stress and damage to the buildings. This happens even on "land" that is frozen, buildings sitting on permafrost in Canada's North experience issues with this in some locations.
Quote from: nadreck on 05/12/2016 05:55 pmQuote from: TomH on 05/12/2016 05:44 pmQuote from: CuddlyRocket on 05/12/2016 01:56 amInteresting for the modular, movable construction.I am surprised at the elevated pods. This leaves the underside exposed, increasing the amount of surface area exposed to radiant x convective thermal loss. Putting it on the surface with closed cell foam insulation under the bottom and sides that aerodynamically deflect convective winds would be much more efficient in such a cold environment.However the downside is that escaping heat causes the ice below to melt which causes uneven subsiding leading to stress and damage to the buildings. This happens even on "land" that is frozen, buildings sitting on permafrost in Canada's North experience issues with this in some locations.I agree that such can happen, however if you have enough insulation, that does not necessarily have to happen.
Would a mars habitat have to do this? I guess it depends on water content of the surface formation they place it on.... high water content formations (such as buried glaciers) might have this issue too?
Quote from: Lar on 05/12/2016 07:27 pmWould a mars habitat have to do this? I guess it depends on water content of the surface formation they place it on.... high water content formations (such as buried glaciers) might have this issue too?No. Not enough precipitation to make this matter.People say Mars is harder than Antarctica, and it clearly is, but there are some ways in which it is easier.
Quote from: Robotbeat on 05/12/2016 07:38 pmQuote from: Lar on 05/12/2016 07:27 pmWould a mars habitat have to do this? I guess it depends on water content of the surface formation they place it on.... high water content formations (such as buried glaciers) might have this issue too?No. Not enough precipitation to make this matter.People say Mars is harder than Antarctica, and it clearly is, but there are some ways in which it is easier.I don't think it has anything to do with precipitation.
...I'm more thinking about the considerations for siting a structure on top of something with high frozen water content. And what happens if that water melts under the structure. The permafrost angle, in other words. It's not about precipitation per se.......
Quote from: Lar on 05/13/2016 02:52 am...I'm more thinking about the considerations for siting a structure on top of something with high frozen water content. And what happens if that water melts under the structure. The permafrost angle, in other words. It's not about precipitation per se.......You will be glad to know that because of the near-vacuum atmospheric pressure, water on Mars sublimates directly from solid to gaseous state. You will have other civil engineering problems, but not permafrost.
Quote from: Ionmars on 05/14/2016 10:10 pmQuote from: Lar on 05/13/2016 02:52 am...I'm more thinking about the considerations for siting a structure on top of something with high frozen water content. And what happens if that water melts under the structure. The permafrost angle, in other words. It's not about precipitation per se.......You will be glad to know that because of the near-vacuum atmospheric pressure, water on Mars sublimates directly from solid to gaseous state. You will have other civil engineering problems, but not permafrost. When it sublimes away, will the resultant material left behind still evenly support the weight above it?
Is the whole surface of Mars permafrost?
.........Fourth; While building underground would, to an extent, alleviate some of these problems as well, you'd still have to build a sort of "Thermos Bottle" structure around the main part of the structures to avoid heat loss there as well. Mechanical isolation from conductive surfaces works far better than even the highest R value insulation. Besides, near vacuum is pretty much the standard on Mars and has no real Mass penalties.......... Overall, this thermal issue is not insurmountable, but requires a lot of thought before landing people in colonies on Mars.
Heat loss will be mitigated somewhat due to the minimal atmosphere on mars - so most heat loss will be through the ground. The problem will be more directed than in Antarctica.
Good ol Camp Century in Greenlandhttps://en.wikipedia.org/wiki/Project_Iceworm
Quote from: TomH on 05/11/2016 04:22 amQuote from: Lar on 05/11/2016 03:00 amClearly you'd need "synthetic limestone"I don't know how you would concentrate the calcium. I'm not sure how much calcium is in Mars regolith. On Earth, you get it from limestone, beds of shells and bones that have not yet compacted to sedimentary rock, and you can distill it from well water. Even if there is as much on Mars as on Earth, the mechanisms to concentrate it would be difficult at best. I am not sure what else could sat as a binder. This doesn't even consider the hardness and purity necessary in the sand and gravel aggregate.Or you could use a different element. One possibility is sulfur.I found:"A Novel Material for In Situ Construction on Mars:Experiments and Numerical Simulations"Lin Wan, Roman Wendner, Gianluca Cusatishttp://arxiv.org/abs/1512.05461found via:https://www.technologyreview.com/s/545216/materials-scientists-make-martian-concrete/
Quote from: launchwatcher on 05/11/2016 05:04 amQuote from: TomH on 05/11/2016 04:22 amQuote from: Lar on 05/11/2016 03:00 amClearly you'd need "synthetic limestone"I don't know how you would concentrate the calcium. I'm not sure how much calcium is in Mars regolith. On Earth, you get it from limestone, beds of shells and bones that have not yet compacted to sedimentary rock, and you can distill it from well water. Even if there is as much on Mars as on Earth, the mechanisms to concentrate it would be difficult at best. I am not sure what else could sat as a binder. This doesn't even consider the hardness and purity necessary in the sand and gravel aggregate.Or you could use a different element. One possibility is sulfur.I found:"A Novel Material for In Situ Construction on Mars:Experiments and Numerical Simulations"Lin Wan, Roman Wendner, Gianluca Cusatishttp://arxiv.org/abs/1512.05461found via:https://www.technologyreview.com/s/545216/materials-scientists-make-martian-concrete/Here's a crazy idea; Melt the regolith and make it into basaltic rock. Essentially, by melting the rocks and dust, you can collect the released gases and fluids while making a usable building material. Either mold it into whatever shape you need or simply mold it into interlocking bricks. (Like stone Legos). You'd still need some form of sealant for pressurized structures with the bricks, but the use of solar heating should provide sufficient energy to either melt the dust and rock into a molten mass or at the least, fuse the dust and rocks into building blocks. Remember, simple works.
Before fly-in fly out became the norm, mining was done with complete communities and infrastructures. The Fermont city, with its windbreak wall is another interesting mining community. In this case there are not only workers but schools, shopping centers and restaurants in the wall. Individual houses are behind the wind break.It's not on permafrost though.The mine, an iron mine called Mt Wright, is about 20 km away.
The biggest problem is *boredom*, not the climate or living arrangement. Living in a single building becomes boring. I think this will be the biggest challenge facing Mars colonists. Most people in my hometown usually have a wood heated no electricity no water cabin to escape the boredom.
And yet they have (somewhat half of the year) a good environment for creating solar power.Light available for 24 hours a day, vast areas, so they can install the panels almost vertically, gaining the same exposure as on equatorial locations and yet it's so freezing cold, that the panels run at high efficiencly (solar panel efficiency is indirect proportional to the temperature of the panel), and nearly no panel degradation (degradation is also heat related).The same thing will happen on Mars, low temperature means low degradation and higher efficiency. Just wipe of that dust once a month.