QUESTION:
How do you use the toliet on mars, and what is the cheepest way of
doing this? will a siphon work? Also, what about taking a bath, or
brushing your teeth? I understand that there is a probable underground
water source, and that there is obviously strong enough gravity on
mars to hold "it" down, but I am still perplexed.

ANSWER from Geoff Briggs on May 30, 2000:
This is out of my field. Presumably there is information available at
NASA-JSC about hygiene arrangements on the Shuttle and Space Station.
On Mars the problems are not so difficult as they are in zero gravity
because martian gravity is about 40% of Earth's so regular plumbing
for baths, showers and faucets should work pretty much as normal.

Waste disposal is of course a problem to be dealt with. I don't know
what physical-chemical scheme is likely to be most efficient.

We expect that there will be liquid water available at depths of a
couple of miles where temperatures are much warmer than at the
surface.  At shallower depths water would be in the form of ice. It
may be a long time before we have convenient access to liquid water on
Mars.