Water, on Mars.

[theweaselking]

Comments

[anton-p-nym.livejournal.com]

My brain's a bit fuzzy, but IIRC liquid CO2 can only form under very high pressures... and Mars's atmosphere is much thinner than ours, so dry ice sublimates there at least as well as it does here.

-- Steve's rooting for the brine theory, himself.