The persistence of equatorial ground ice on Mars

In the current Martian climate, ground ice is unstable in the equatorial regions and, if present, would undergo sublimation and diffusive loss to the atmosphere. Previous studies suggest that the ice table (the uppermost occurrence of ice in the regolith) would continuously recede throughout geologic history. We present new models of the behavior of ice in the Martian equatorial regolith which predict that porous interstitial ice will persist at relatively shallow depths for geologically long periods of time. The persistence of interstitial ice is due to recondensation of water vapor as it diffuses toward the surface, encountering colder temperatures. We discuss the implications for the formation of rampart craters and debris aprons.