Sand dunes around the Martian polar cap may be the most active geologic features on the planet, according to a new paper in Science, using images from the UA's HiRISE camera on the Mars Reconnaissance Orbiter. There are both sudden and gradual changes in the dunes, which are surprising researchers.
[right, Seasonal activity in a Martian dune: Every year, a seasonal polar cap of condensed carbon dioxide (dry ice) covers dune fields at high latitudes. Spring found the ice changing from solid to gas, causing sand to avalanche down the dune (middle). The following summer, the ice was gone. Instead, wind ripples appeared on the debris apron (bottom). Credit: NASA/JPL/The University of Arizona. Caption from UA news release]
Ref: Seasonal Erosion and Restoration of Mars’ Northern Polar Dunes, Science 4 February 2011:Vol. 331 no. 6017 pp. 575-578, DOI: 10.1126/science.1197636