Slope Streaks within an Impact Crater in Terra Sabaea
NASA/JPL/University of Arizona
Slope Streaks within an Impact Crater in Terra Sabaea
PSP_005369_1925  Science Theme: Impact Processes
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This image shows the portions of the interior slopes and central uplift of an approximately 25 kilometer (approx. 16 mile) diameter impact crater in the Terra Sabaea region of Mars.

Along the slopes of the crater walls and flowing down the central uplift are hundreds of dark slope streaks, features that are up to a few hundred meters wide and several kilometers long. They generally start at a point and widen downslope as a single streak or branch into two or more streaks.

Many hypotheses have been proposed for how they formed on the surface, such as liquid stains or flows, dry avalanching, geochemical weathering, and moisture wicking. Recent observations of dark slope streaks at 78 unique sites in HiRISE images have shown that they have topographic relief where the dark interior surface is lower than the surroundings. The relief is most apparent in images that have low sun illumination (i.e., sun low in the sky), where the dust is sufficiently thick, and along slopes facing away from the sun.

These results by Chuang et al. (2007), soon to be published in Geophysical Research Letters, indicates that material must have been removed in the formation of streaks. Their conclusion is that slope streaks are most likely formed by avalanches of dry dust, similar to previous conclusions by other authors on this subject.

Written by: Frank Chuang  (17 October 2007)

This is a stereo pair with PSP_005514_1925.
 
Acquisition date
18 September 2007

Local Mars time:
14:11

Latitude (centered)
12.207°

Longitude (East)
26.387°

Spacecraft altitude
276.4 km (172.8 miles)

Original image scale range
27.7 cm/pixel (with 1 x 1 binning) so objects ~83 cm across are resolved

Map projected scale
25 cm/pixel and North is up

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Equirectangular

Emission angle:
3.3°

Phase angle:
46.6°

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

Solar longitude
316.2°, Northern Winter

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North azimuth:  97°
Sub-solar azimuth:  324.1°
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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.