QUESTION:
What is the maximum mass of gas Mars could hold in its atmosphere?

ANSWER from Bruce Jakosky on July 23, 1998:
Within reasonable bounds, there is no maximum amount of gas that the martian
atmosphere could hold.  Although gas is escaping at present, and has done so
in the past, the escape rate does not strongly depend on the total amount of
gas.  At some extreme amount, though, I could imagine the atmosphere being
so extended that the gas at the top would be loosely bound and might escape
quickly; however, this sounds more like the evolution of a small gas-giant
planet!