Shapes and Spots on a Polar Sand Dune
NASA/JPL/University of Arizona
Shapes and Spots on a Polar Sand Dune
ESP_034441_2565  Science Theme: Seasonal Processes


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This image shows numerous dark shapes and bright spots on a sand dune in the Northern polar regions of Mars.

The bright spots are carbon dioxide frost. On Mars, the main atmospheric component is carbon dioxide, which circulates seasonally between the atmosphere and the polar regions. One of the reasons that permit this process is the fact that temperatures on Mars are much colder than on Earth, which allows carbon dioxide frost to condense on the surface in winter.

When spring comes however, the surface heats up and the carbon dioxide frost eventually sublimates (turns directly from the solid to the vapor state), and forms jets of carbon dioxide mixed with dust, leading to the formation of the dark features we see in the image.

Such processes occur seasonally on Mars, and therefore are continuously being monitored by the HiRISE scientists to assess the differences from one year to the next.

Written by: M. Ramy El-Maarry (audio by Tre Gibbs)   (22 January 2014)

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Acquisition date
01 December 2013

Local Mars time:

Latitude (centered)

Longitude (East)

Range to target site
319.3 km (199.6 miles)

Original image scale range
31.9 cm/pixel (with 1 x 1 binning) so objects ~96 cm across are resolved

Map projected scale
25 cm/pixel

Map projection

Emission angle:

Phase angle:

Solar incidence angle
58°, with the Sun about 32° above the horizon

Solar longitude
56.8°, Northern Spring

North azimuth:

Sub-solar azimuth:
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Black & white is 5 km across; enhanced color about 1 km
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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:
NASA/JPL/University of Arizona

For information about NASA and agency programs on the Web, visit: 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.