A Dune Field near Nili Patera
NASA/JPL/University of Arizona
A Dune Field near Nili Patera
ESP_057071_1890  Science Theme: Aeolian Processes
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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, giving this particular shape.

The orientation of these dunes tell us that the prevailing wind blows from the right to the 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.

Written by: Susan Conway (audio: Tre Gibbs)  (4 February 2019)
 
Acquisition date
29 September 2018

Local Mars time
14:49

Latitude (centered)
8.714°

Longitude (East)
67.348°

Spacecraft altitude
270.5 km (168.1 miles)

Original image scale range
from 27.3 cm/pixel (with 1 x 1 binning) to 54.5 cm/pixel (with 2 x 2 binning)

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
6.5°

Phase angle
47.8°

Solar incidence angle
53°, with the Sun about 37° above the horizon

Solar longitude
259.4°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  325.3°
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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.