This crater, formed in 2008, exposes shallow, clean ice that is not uncommon in the middle-to-high latitudes on Mars. Sublimation, the process that occurs when a solid changes into a gas without an intermediary liquid stage, creates an ice-free layer on the surface that may be several feet deep, hiding the ice underneath until exposed by an impact.
This image taken on May 19, 2010, shows an impact crater that had not existed when the same location on Mars was previously observed in March 2008. The new impact excavated and scattered water ice that had been hidden beneath the surface. The location is at 63.9 degrees north latitude, 44.9 degrees east longitude.
Image credit: NASA/J