Gypsum-Rich Dunes in Olympia Undae
NASA/JPL/University of Arizona
Gypsum-Rich Dunes in Olympia Undae
PSP_010071_2615  Science Theme: Polar Geology
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In this enhanced-color image are dunes within the largest collection of dunes on Mars, Olympia Undae, near the margin of the north polar deposits, Planum Boreum.

This section of Olympia Undae is particularly interesting because the dunes are rich in gypsum, a mineral that forms in the presence of water. The material comprising these dunes is thought to have eroded from geologic units near the base of the polar deposits, but these units have poor to no gypsum content. Therefore, water likely affected these dunes after the sand had eroded out from the polar deposits. Several ideas have been proposed to explain the formation of gypsum, including hydrothermal (hot water) activity and melting of water-ice in the polar deposits.

While gypsum dunes on Earth (for example, at White Sands, New Mexico) are white (the color of gypsum), these Martian dunes are dark due to the presence of basaltic grains that lower the brightness of the dunes. CRISM, another instrument on MRO, has found that the crests of the dunes are the most gypsum-rich.

So, what is the bright, polygonally-fractured material in the low spaces between the dunes? Perhaps it is polar ice lying beneath, desiccated (dried) gypsum material whose fine grain size makes it difficult for CRISM to detect, or something else altogether.

Written by: Kate Fishbaugh  (12 November 2008)
 
Acquisition date
19 September 2008

Local Mars time:
14:22

Latitude (centered)
81.506°

Longitude (East)
139.626°

Spacecraft altitude
321.0 km (200.6 miles)

Original image scale range
from 32.1 cm/pixel (with 1 x 1 binning) to 128.4 cm/pixel (with 4 x 4 binning)

Map projected scale
25 cm/pixel

Map projection
Polarstereographic

Emission angle:
0.1°

Phase angle:
64.1°

Solar incidence angle
64°, with the Sun about 26° above the horizon

Solar longitude
129.4°, Northern Summer

For non-map projected images
North azimuth:  109°
Sub-solar azimuth:  325.0°
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RGB color
non map           (243MB)
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HiView

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IRB: infrared-red-blue
RGB: red-green-blue
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Black & white is 5 km across; enhanced color about 1 km
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USAGE POLICY
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

POSTSCRIPT
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.