THE PERSISTENCE OF EQUATORIAL GROUND ICE ON MARS

In the current Martian climate, ground ice is unstable in the equatori al regions and, if present, would undergo sublimation and diffusive lo ss to the atmosphere. Previous studies suggest that the ice table (the uppermost occurrence of ice in the regolith) would continuously reced e throughout geologic history. We present new models of the behavior o f ice in the Martian equatorial regolith which predict that porous int erstitial ice will persist at relatively shallow depths for geological ly long periods of time. The persistence of interstitial ice is due to recondensation of water vapor as it diffuses toward the surface, enco untering colder temperatures. We discuss the implications for the form ation of rampart craters and debris aprons.