NASA - Mars Reconnaissance Orbiter (MRO) logo.
Feb. 11, 2019
A Dune Field Near Nili Patera
In this image many sand dunes are visible. They have an elongated crescent form and are called "barchan dunes." They are formed by the continuous action of the wind blowing in the same direction.
The orientation of these dunes tells us that the prevailing wind blows from right to left (east to west). The wind is continuously moving sand grains up the longer dune slope, towards the top. The small ripples on the slope are caused by this movement. When the sand grains arrive at the top, they fall down the steeper and shorter slope, which as a consequence, has no ripples. It is this gradual sand movement that causes the dunes to slowly move over time.
The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. (The original image scale is 27.3 centimeters [10.7 inches] per pixel [with 1 x 1 binning] to 54.5 centimeters [21.5 inches] per pixel [with 2 x 2 binning].) North is up.
The Red Planet's Layered History
The geologic history of a planet is written in its layers. Erosion of the surface reveals several shades of light toned layers, likely sedimentary deposits, as shown in this image taken by the HiRISE camera on the Mars Reconnaissance Orbiter. The most recent geologic features are the narrow sand dunes snaking across the top of all the rocks.
HiRISE operates in visible wavelengths, the same as human eyes, but with a telescopic lens that produces images at resolutions never before seen in planetary exploration missions. These high-resolution images enable scientists to distinguish 1-meter-size (about 3-foot-size) objects on Mars and to study the morphology (surface structure) in a much more comprehensive manner than ever before.
Mars Reconnaissance Orbiter (MRO)
The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.
Mars Reconnaissance Orbiter (MRO): http://www.nasa.gov/mission_pages/MRO/main/index.html
Images, Text, Credits: NASA/Tony Greicius/JPL-Caltech/University of Arizona.
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