Image PSP_002824_1355 shows a sand dune field in Rabe Crater. Rabe crater is approximately 100 km in diameter and is located in the southern highlands of Mars.

The dune field within the crater has dimensions of roughly 50 km x 35 km, making it one of the largest dune fields in the region. It is composed mostly of barchanoid and transverse dunes that formed from uni-directional winds from the southeast. The sand grains are believed to be basalt, a common volcanic rock, that eroded from sedimentary units (made of eroded lava) exposed in a pit on the floor of Rabe Crater.

The dark toned streaks seen on the dune slip face in the subimage are believed to form from grain-flow events, or sand avalanches, that occur when wind carries sand grains over the crest of the dune and deposits them on the slip face oversteepening the slope. (1141x775; 2 MB). When compared with older images, the identification of new streaks in HiRISE images could indicate that these dunes are still active today. Also seen in the subimage are smaller secondary dunes superimposed on the surface of the large dunes.

Written by: Maria Banks

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible: Image: NASA/JPL/University of Arizona

For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.