Sand Dunes and Ripples in Proctor Crater
NASA/JPL/University of Arizona
Sand Dunes and Ripples in Proctor Crater
ESP_011909_1320  Science Theme: Aeolian Processes
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This HiRISE image shows two classes of aeolian bedforms within Proctor Crater. The relatively bright, small ridges are ripples. From their study on Earth, and close-up examination by the MER rovers (roving elsewhere on Mars), we know that ripples are composed of fine sand (less than 200 microns in diameter) or fine sand coated with coarser sand and granules.

The larger, darker bedforms are dunes composed of sand, most likely of fine size. Ripples tend to move slower than dunes. Because of this, over time, ripples get covered with dust, possibly explaining the bright tone visible here. The dunes are dark probably because they are composed of basaltic sand (derived from dark, volcanic rock) that is blown by the wind enough that dust does not sufficiently accumulate to change their color.

This area in Proctor Crater is being monitored by HiRISE to document any changes over time.

Written by: Nathan Bridges   (9 March 2009)

This is a stereo pair with PSP_003101_1320.

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Acquisition date
09 February 2009

Local Mars time:

Latitude (centered)

Longitude (East)

Range to target site
253.2 km (158.3 miles)

Original image scale range
50.7 cm/pixel (with 2 x 2 binning) so objects ~152 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle:

Phase angle:

Solar incidence angle
62°, with the Sun about 28° above the horizon

Solar longitude
206.7°, Northern Autumn

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.