human habbitat on another planet

[kelvinzero]

Kelvin, I would be very interested to look at your calculations if you can find them. Water trick sounds neat, but as Tampa mentioned you would need a bubble still. I was also thinking that if there was a jupiter like planet somewhere in other system with a solid core, a pretty shallow hole could be used as all the outer layer of hydrogen would produce the requred pressure on top of the hole filled with air.

Sorry, They were on this site somewhere but they seem to have been deleted.
I think one version used this formula http://en.wikipedia.org/wiki/Atmospheric_pressure.. but I dont remember what assumptions I made for temperature or molar mass.

The calculation for water is simpler because it doesnt compress. Not over 30 meters anyway.
The mass of a cubic meter of water is 1000kg.
The mass of a column of water h meters high and 1 square meter wide is h*1000kg.
The weight of this column of water on mars is F= m*a = (h*1000kg)*(3.7 m/s²)
The pressure of this column of water is found by dividing force by area:
pressure = h*1000*3.7(Pa) where a Pa is a Pascal, or (newtons/meter^2)
The airpressure at sealevel is about 100 kPa, or 100,000pa.
Solving for 100,000 = h*1000*3.7,
h= (100/3.7)(m) = 27 meters.

As for water.. you dont exactly need a bubble. Firstly Water can seal itself with an ice layer. But more importantly it cannot rupture catastrophically the way a bubble can. If you were at a depth of thirty meters under water on mars, and the ice surface was suddenly shattered, you would not be sucked out into the near vacuum of mars's surface. All that would happen is that the water at the surface would begin to boil off into the vacuum. You would have a while before you were in danger.

There isnt really any cost in maintaining a water environment because all human activity creates waste heat. For largescale powerplants getting rid of this heat is a huge problem. It is one of the big limitations for using nuclear power in space. Any powerplant under the ice on mars or any of the various icy worlds around the solar system will surround itself in a very earth(ocean)like environment of circulating water, with pressure and protection from cosmic radiation.