Exposed subsurface ice sheets in the Martian mid-latitudes

Water ice cliffs on MarsSome locations on Mars are known to have water ice just below the surface, but how much has remained unclear. Dundaset al.used data from two orbiting spacecraft to examine eight locations where erosion has occurred. This revealed cliffs composed mostly of water ice, which is slowly sublimating as it is exposed to the atmosphere. The ice sheets extend from just below the surface to a depth of 100 meters or more and appear to contain distinct layers, which could preserve a record of Mars' past climate. They might even be a useful source of water for future human exploration of the red planet.Science, this issue p.199