This north polar dune field is bounded by a small unnamed crater about 11 kilometers in diameter in the Vastitas Borealis region. This crater captured deposits of basaltic sand that may have been transported from the North Polar Erg, a massive sea of sand that surrounds the Martian northern pole.

This region experiences a variety of winds that blow from various directions during different seasons and times of day, and the winds are also affected by the topography of the crater itself. This influences the movement of sand within the crater and the dunes that they shape.

This image shows many transitioning dunes which indicate changes of wind direction. The wind direction can be inferred from the location of the steeper side of the dune (called the slip-face) which is downwind of the dominant wind direction. The barchans and barchanoid dunes form crescent shapes and are consistent with dominant winds from the southwest.

Towards the center of the dune field, the barchans transition from crescent shapes into irregular, more elongated dunes and merge. The more northern part of the dune field consists of longitudinal dunes which extend from the horns of modified barchans in the central part of the dune field. These longitudinal dunes form along the trend of southerly-southeasterly winds.

Because it is early summer, solar radiation has heated the sand and there are only a few small patches of frost remaining on the dunes at this season. However, evidence of the arctic climate is visible in the polygons surrounding the dune field. The polygons, like those found at the Phoenix Mission landing site, are produced by freeze-thaw cycles as the polar soil expands and contracts.

Written by: Circe Verba/P Geissler

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.