PIA20743: North Polar Gypsum Dunes in Olympia Undae
 Target Name:  Mars
 Is a satellite of:  Sol (our sun)
 Mission:  Mars Reconnaissance Orbiter (MRO)
 Spacecraft:  Mars Reconnaissance Orbiter (MRO)
 Instrument:  HiRISE
 Product Size:  2880 x 1800 pixels (w x h)
 Produced By:  University of Arizona/HiRISE-LPL
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 Full-Res TIFF:  PIA20743.tif (15.56 MB)
 Full-Res JPEG:  PIA20743.jpg (1.106 MB)

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These sand dunes are a type of aeolian bedform and partly encircle the Martian North Pole in a region called Olympia Undae.

Unlike most of the sand dunes on Mars that are made of the volcanic rock basalt, these are made of a type of sulfate mineral called gypsum. Whence the sand? Well, gypsum is a mineral that can often form from the evaporation of water that has sulfur and calcium dissolved in it. This sand was probably sourced from a northern region on Mars that used to be quite wet. The boxy gridding of the dunes indicates that the wind blows in multiple directions.

Note: "Aeolian" means wind-blown and "bedform" means piles of sediment shaped by a flowing fluid (liquid or gas).

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.

Image Credit:
NASA/JPL-Caltech/Univ. of Arizona

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