NASA-International Space Station

Dunes of sand-sized resources have been trapped on the floors of many Martian craters. This picture shows dunes inside a crater in Noachis Terra, west of the giant Hellas impact basin in Mars' southern hemisphere.

The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter captured this view on Dec. 28, 2009. The orbiter resumed making remarks in mid-December following a three-month hiatus. A set of new images from the HiRISE camera is on the camera team's site, at http://hirise.lpl.arizona.edu/nea.php.

The dunes here are linear, thought to be due to changing wind directions. In places, each dune is extraordinarily similar to adjacent dunes, including a reddish (or dust-colored) band on northeast-facing slopes. Large pointed boulders litter the floor between dunes.

The most widespread linear dune fields known in the solar system are on Saturn's large moon Titan. Titan has a very different environment and composition, so at meter-scale resolution they in all probability are very different from Martian dunes.

The University of Arizona, Tucson, operates the HiRISE camera, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft.