Unlike on Earth, the snow and ice on MARS is carbon dioxide, better known to us as dry ice.
When the sun starts shining on it in the Spring, the ice on the smooth surface of the dune cracks and escaping gas carries dark sand out from the dune below, often creating beautiful patterns. On the rough surface between the dunes, frost is trapped behind small sheltered ridges.
NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calififornia, manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington.
The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.