On Tue, 9 Aug 2005, James Newton, Host wrote:

> If the purity of the ice is sufficient, it could also be used as a shield;
> allowing light to penetrate to some degree while providing protection from
> meteors which the atmosphere would not. Digging out a home under the ice may
> well be less expensive and safer than building a dome.

I don't know what your references on this are, but:

1) ice is soft as a material compared to rock/sand. It takes more ice 
above one's bunker to protect properly from a given threat than 
dirt/earth. Only plus: It stops neutrons more than dirt and may be a 
better insulator than rock (but worse than sand or dust).

2) ice a few meters deep is completely opaque, unless it is crystalised. 
Most natural ice isn't afaik. Ice made from packed snow is particularly 
opaque. One meter of that and you're in the darkroom. There are reports 
of people buried in avalanches in broad daylight who could not make out 
'up' because it was totally dark only one meter below.

> It might be that shaping the outside of the ice could concentrate the
> available solar energy and allow for crops or other energy needs deep in the
> safety of the ground.
>
> Would the ice also provide protection from radiation?

Yes, but it depends on what is in the ice. For example a radiation 
shield made of tritium rich frozen water is not a good idea. Same thing 
for inclusions in water, like salts (Chlorine and Iodine).

I have been reading up on these things recently ;-)

So ... according to the following document up to 53% of the polar areas 
surface may be water by mass:

http://www.ingentaconnect.com/content/maik/sols/2004/00000038/00000004/00494842

But as to that skating ring, I think that the most interesting thing 
would be to drill in it and look for life. If there ever was something 
larger than bacteria on Mars then its remains should be found in the 
ice. I also think that *skating* (or ice-walking) robots will be a 
subject of intense study in the near future.

Peter
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