Dunes and Polygons in Olympia Undae
NASA/JPL/University of Arizona
Dunes and Polygons in Olympia Undae
PSP_001736_2605  Science Theme: Aeolian Processes


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This observation shows dark dunes and light polygonal terrain in Olympia Undae, also known as the North Polar Erg.

Two sets of dunes are obvious. The major set trends North-South, indicating winds from the East or West. Between the crests of these dunes is a second set oriented mostly East-West.

Zooming in on the dunes, a rippled texture is apparent, probably due to redistribution of sand at the scale of meters and less. Near the crests of some dunes are channel-like features, with some branching downslope. The origin of these channels is unknown, but they may result from the flow and displacement of sand that was fluidized by sublimating carbon dioxide or water frost.

Bright patches of ground are found in some inter-dune areas, with many having a polygonal texture. Polygons on Earth form from contraction induced by stresses from dehydration, cooling, and other processes, so these features may have a similar origin. The CRISM instrument on MRO and OMEGA on Mars Express indicates that many dunes in Olympia Undae are rich in the mineral gypsum.

Written by: Nathan Bridges  (14 March 2007)

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Acquisition date
09 December 2006

Local Mars time:

Latitude (centered)

Longitude (East)

Range to target site
316.4 km (197.7 miles)

Original image scale range
31.6 cm/pixel (with 1 x 1 binning) so objects ~95 cm across are resolved

Map projected scale
25 cm/pixel

Map projection

Emission angle:

Phase angle:

Solar incidence angle
69°, with the Sun about 21° above the horizon

Solar longitude
147.9°, Northern Summer

North azimuth:

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

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.