Huge escarpments of quite pure water ice have been found in the Southern Highlands of Mars — accessible enough that astronauts might some day be able to turn the ice into water, hydrogen and oxygen.
Some of these deposits are more than 100 meters thick and begin only a meter or two below the surface.
These are among the conclusion from a new paper in the journal Science that describes these previously unknown water ice reserves. While Mars scientists have long theorized the presence of subsurface ice under one-third of the planet, and even exposed bits of it with the Phoenix lander, the consensus view was that martian ice was generally cemented with soil to form a kind of permafrost.