This image shows a traverse across a section of the North Polar erg, a vast sea of sand that surrounds the polar cap.

The source of the dunes may be from the eroding north polar layered deposits. Wind, acting on this mixture of sand, dust, and ice, has formed several dune types on top of bright megaripples and polygons. A dark mantle of sand lies beyond the dunes.

The central part of the field contains transverse dunes with the dominant wind direction coming from the northwest-west. The outer edges of the dune field transition into star dunes (with multiple arms) and barchanoid dunes (crescent-like shape). The star dunes indicate a multidirectional wind regime or a change in wind direction over the dune field’s evolution. The dunes are somewhat confined to their location and may have taken hundreds of years to form.
Written by: Circe Verba

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.