Ice table covered by loose soil (hollow out a house under the ice?)

[Martin]

I've tended to think of Mars as not practical to inhabit because I was skeptical that it had a thick permanent layer of ice (except possibly right at the poles)

 

The polar caps seem unstable and change seasonally.

 

But this picture makes me think:

http://phoenix.lpl.arizona.edu/images.php?gID=0&cID=34

 

it shows the lander's rocket nozzles pointing down at what looks like two patches of ice that they appear to have cleared by blowing away the soil

 

the release refers to them as a possible ice TABLE

http://phoenix.lpl.arizona.edu/05_31_pr.php

 

==QUOTE==

"This suggests we have an ice table under a thin layer of loose soil," said the lead scientist for the Robotic Arm Camera, Horst Uwe Keller of Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany.

 

"We were expecting to find ice within two to six inches of the surface," said Peter Smith of the University of Arizona, Tucson, principal investigator for Phoenix. "The thrusters have excavated two to six inches and, sure enough, we see something that looks like ice. It's not impossible that it's something else, but our leading interpretation is ice."

==endquote==

 

So now the question is how thick is that layer? How strong, how extensive and integral is it?

 

For some years I've tended to prefer strategies of extending earth life to places that pretty clearly have several kilometer thick ice, like Europa Ganymede and Ceres.

Because that is the key to providing a safe earthlike environment, with decent atmospheric pressure, and stable temperature. Shielding from radiation and other overhead hazards. And relative cheapness. You just hollow out what is there. So sheet ice is structurally efficient.

 

and there's guaranteed to be enough water

 

So I've tended to be skeptical and dubious about Mars.

 

But if Mars actually has a thick stable layer over a geographically significant area that would be apt to change how I think about it.

 

Well there is still plenty of room for disappointment. The layer might be only a few meters thick! What I was thinking about should really have hundreds of meters---or several kilometers. Take a nuclear reactor down there and melt a big cave and make a small ocean and light the cave artificially and grow stuff. Algae, fish. The thicker the roof the slower heat can escape and the easier to maintain a temperature around zero celsius. Could Mars have some really thick ice under that dry-looking soil?

Edited June 2, 2008 by Martin

[Phi for All]

How thick is thick? Have there been any estimates as to the depth of the ice table, Martin?

[Martin]

How thick is thick? Have there been any estimates as to the depth of the ice table, Martin?

 

Hey! You interested in this too?

 

I don't know any estimates. One motive for starting thread is to find out if some of the rest of us have seen estimates.

 

I did some rough calculations some years back and IIRC I came up with the idea that you needed several hundred meters icesheet, minimum.

 

Some problems were that you are creating this large bubble under the ice, filled with breathable atmosphere at around earth-normal pressure. And you don't want the bubble to gradually migrate towards the surface----by having the ceiling slowly melt and the floor freeze.

 

And for efficiency you want the roof to be thick because the thicker it is the better it insulates.

 

The air should all be fairly close to zero Celsius to keep the surrounding walls and ceiling frozen.

 

I remember deciding I'd be nervous without around 100 meters of ice above my head. Or at least that much to play around with. I was thinking of Mars at the time---the polar caps.

 

I'd want a bubble large enough to fly in, with manpower craft. That seems to be the big joy of living on a lower gravity planet. Your muscles are adequate for flight.

 

A small bubble, well you could have a skating rink. Thats a bit like flying. It's good for people to have fun. A larger bubble would be more fun, and scenic.

 

=======================

 

Ceres might still be better than Mars. You have thick ice even at the equator. You don't have to restrict to high latitudes with their long dark winters.

On Ceres you could take the elevator up to the surface and suit up and go thru the airlock and be on a sunlit surface, any time of year.

You wouldnt need the bubble located in high latitudes.

Edited June 2, 2008 by Martin