On the Beauty of Yardangs
NASA/JPL/University of Arizona
On the Beauty of Yardangs
ESP_040504_1920  Science Theme: Aeolian Processes
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Some geological materials (like solid rock) are incredibly tough, but others (like piles of volcanic ash) are quite soft. Some materials are soft enough that they can be eroded by the wind alone and yield landscapes that look like what we see in this HiRISE image.

The long straight ridges seen here are called yardangs and they form on Mars (and Earth) when the wind strips away the inter-ridge material. This process is greatly aided when the wind is also blowing sand along. The sand grains do an effective job at stripping away loose material: these ridges are literally being sandblasted.

Yardangs are useful features to recognize because the tell us the direction the wind is blowing in. They take a long time to form so this direction is the dominant wind orientation averaged over a long period of time (which might be quite different that the winds on Mars today). These yardangs also tell us that the surface here is made up of loose weak material and this information, in conjunction with other data, can tell us what the material is composed of and what the history of this particular site on Mars has been.

Written by: Shane Byrne  (6 May 2015)
 
Acquisition date
18 March 2015

Local Mars time:
14:17

Latitude (centered)
11.952°

Longitude (East)
199.841°

Spacecraft altitude
280.0 km (175.0 miles)

Original image scale range
56.0 cm/pixel (with 2 x 2 binning) so objects ~168 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection
Equirectangular

Emission angle:
0.2°

Phase angle:
46.0°

Solar incidence angle
46°, with the Sun about 44° above the horizon

Solar longitude
310.3°, Northern Winter

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  324.7°
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Black & white is 5 km across; enhanced color about 1 km
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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.