Migrating and Static Sand Ripples on Mars
Migrating and Static Sand Ripples on Mars
ESP_032616_1275  Science Theme: Aeolian Processes
Having operated at Mars for more than seven years, MRO and the HiRISE camera continue to make new discoveries. One of these is that many sand dunes and ripples are moving, some at rates of several meters per year.

In this observation, a dune field in a Southern Hemisphere crater was observed approximately one Mars year apart, first on 2 September 2011 and then again on 11 July 2013 (a year on Mars is 687 Earth days). By taking images at the same time of year, solar illumination angles are the same, so that subtle apparent changes can be linked to true displacement on the surface and not artifacts.

In these two images, there is little distortion (a digital elevation model would remove more distortion). Here, we focus on the southern and northern part of two adjacent dunes. With an animated image, the displacement of ripples on the dunes relative to nearby rocks and dark ripples are clearly visible. It seems that the ripples on the southern dune are moving northeast, while those on the northern dune are moving west, indicating complex winds in this area. The static dark ripples may be composed of larger grains than those in the dunes and are therefore harder to move.

In most areas of Mars, darker-toned ripples are more mobile than lighter ones. This area is different, demonstrating that continued imaging of the Martian surface results in new findings and revisions of ideas.

Written by: Nathan Bridges  (28 August 2013)

This is a stereo pair with ESP_032748_1275.
Acquisition date
11 July 2013

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
247.6 km (153.9 miles)

Original image scale range
24.8 cm/pixel (with 1 x 1 binning) so objects ~75 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
57°, with the Sun about 33° above the horizon

Solar longitude
350.0°, Northern Winter

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North azimuth:  97°
Sub-solar azimuth:  50.4°
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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’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. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.