Star Dunes in Crater in Tyrrhena Terra
NASA/JPL/University of Arizona

Star Dunes in Crater in Tyrrhena Terra
ESP_017036_1665  Science Theme: Composition and Photometry
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An amazing aspect of Mars that is captured in many HiRISE images is geologic diversity within a small area. This image, of a crater in the Tyrrhena Terra region, was targeted to look at the geologic aspects of possible clays detected with the CRISM instrument.

Fortuitously, a beautiful set of star dunes are visible on the western edge of a small crater within the larger target crater (this smaller crater is in the southwest [lower left] of the image). Star dunes form when sand is blown by winds coming from multiple directions, which is common in craters. This results in intersecting dunes, forming a polygonal, or "star" pattern.

Here we show two zooms of the star dunes. The closest zoom (at right) shows lumpy deposits of sand in the interior of the star patterns, probably resulting from avalanches off of the dune slopes. The dune sands are most likely made of basalt, a common volcanic rock. The possible clay-bearing material is probably within the surrounding bedrock.

Written by: Nathan Bridges   (5 May 2010)

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Acquisition date:15 March 2010 Local Mars time: 3:09 PM
Latitude (centered):-13.271° Longitude (East):93.538°
Range to target site:257.7 km (161.1 miles)Original image scale range:from 25.8 cm/pixel (with 1 x 1 binning) to 51.6 cm/pixel (with 2 x 2 binning)
Map projected scale:25 cm/pixel and North is upMap projection:Equirectangular
Emission angle:2.4° Phase angle:60.4°
Solar incidence angle:59°, with the Sun about 31° above the horizon Solar longitude:64.5°, Northern Spring
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North azimuth:97° Sub-solar azimuth:42.8°
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North azimuth:270°Sub solar azimuth:217.0°

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