Looking for Changes in Dust Drifts West of Alba Mons
NASA/JPL/University of Arizona
Looking for Changes in Dust Drifts West of Alba Mons
ESP_032709_2210  Science Theme: Aeolian Processes
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This image was intended to search for surface changes after three Mars years in a dust-covered region west of the Alba Mons volcano. It was acquired at almost the exact same season as another image in 2007, and the illumination and viewing angles are very similar.

The earlier image showed thick dust deposits accumulated downwind of topographic obstacles, apparently formed by winds blowing across the surface. These deposits, nicknamed “whiskers,” are evidently rare on Mars, so far found in only a few places such as the summit of Tharsis and on the flanks of the giant volcanoes. Their ages and origins are still poorly known. We expected that wind-related changes could be taking place here in particular because of the location's low elevation in comparison to similar dust deposits elsewhere on Mars. The atmosphere is denser at this elevation, near Martian “sea-level,” than at the tops of the giant volcanoes, so the winds are more effective at eroding and transporting sediment.

A comparison of the new image with the image taken in 2007 shows no discernible differences in the dust deposits. Analysis of the full image is still ongoing, but it is already clear that no major surface changes took place in this location over the three Mars year interval between the two pictures. This is instructive because it tells us that the dust deposits are resistant to wind erosion (under normal winds at least; the last major global dust storm was in early 2007, before PSP_006271_2210 was taken) and that no new dust deposition has taken place.

This result suggests that either these deposits form and evolve very slowly, over time scales much longer than three years, or else they formed during a past period when the winds were much stronger than they are today.

Written by: Paul Geissler (audio by Tre Gibbs)   (21 August 2013)

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Acquisition date
19 July 2013

Local Mars time:
14:08

Latitude (centered)
40.870°

Longitude (East)
235.942°

Range to target site
292.5 km (182.8 miles)

Original image scale range
29.3 cm/pixel (with 1 x 1 binning) so objects ~88 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle:
4.1°

Phase angle:
49.6°

Solar incidence angle
52°, with the Sun about 38° above the horizon

Solar longitude
353.8°, Northern Winter

North azimuth:
97°

Sub-solar azimuth:
317.4°
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Postscript
For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. 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. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.