Martian Barchans
NASA/JPL/University of Arizona

Martian Barchans
ESP_014404_1765  Science Theme: Aeolian Processes
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Barchan dunes are common on both Earth and Mars. These dunes are very distinctive in shape, and are important because they can tell scientists about the environment in which they formed.

Barchans form in wind regimes that blow in one dominant direction. The ridged arcs of sand that define the barchan dunes end in horns that point downwind. Sand is transported up the broad, relatively shallow windward slopes and once it overtops the dune crest, the sand falls down a shorter steeper slope between the horns, known as the slip face. Over time, the barchans migrate downwind, following their horns. (The subimage refers to the non-map projected version of the image.)

This HiRISE image shows an example of several barchans merging to form an even larger barchan dune. This can happen through a variety of circumstances, such as when smaller, faster dunes collide with larger, slower-moving dunes that absorb them, resulting in single, larger dunes. The distance between the merging horns of the large dune in this highlighted region is a little over 500 meters (about 1600 feet).

Written by: Andrea Philippoff   (11 December 2009)



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Acquisition date:22 August 2009 Local Mars time: 2:17 PM
Latitude (centered):-3.271° Longitude (East):307.617°
Range to target site:268.3 km (167.7 miles)Original image scale range:26.8 cm/pixel (with 1 x 1 binning) so objects ~81 cm across are resolved
Map projected scale:25 cm/pixel and North is upMap projection:Equirectangular
Emission angle:5.0° Phase angle:30.7°
Solar incidence angle:36°, with the Sun about 54° above the horizon Solar longitude:325.8°, Northern Winter
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North azimuth:97° Sub-solar azimuth:345.8°
For map-projected products
North azimuth:270°Sub solar azimuth:160.6°

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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.