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   (16 June 2010)

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Acquisition date:09 December 2006 Local Mars time: 2:36 PM
Latitude (centered):80.187° Longitude (East):191.216°
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/pixelMap projection:Polarstereographic
Emission angle:2.0° Phase angle:67.8°
Solar incidence angle:69°, with the Sun about 21° above the horizon Solar longitude:147.9°, Northern Summer
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North azimuth:105° Sub-solar azimuth:325.3°
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North azimuth:78.78°Sub solar azimuth:299.9°

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