Alluvial Fans in Mojave Crater
NASA/JPL/University of Arizona
Alluvial Fans in Mojave Crater
ESP_040618_1875  Science Theme: Fluvial Processes
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Stereo data from an anaglyph (or 3D) image shows that the landscape in this observation is pervasively eroded, right up to the tops of the ridges, with channels extending down into depositional fans much like alluvial fans in the Mojave Desert.

This can be explained by something like rainfall, but this crater is geologically young, only a few hundred million years old, when Mars’ atmosphere was thought to be too depleted to support rainfall. From the surrounding region we can see that only the Mojave ejecta is eroded, not adjacent landscapes. This suggests that the ejecta landed wet and itself initiated the erosion, rather than rainfall from clouds.

Subsurface ice may have melted and mixed with the crater ejecta, which fell as a wet slurry of debris. But that's just my favorite theory—other geologists favor different interpretations.

Written by: Alfred McEwen (audio: Tre Gibbs)  (20 May 2015)

This is a stereo pair with ESP_039695_1875.
 
Acquisition date
27 March 2015

Local Mars time
14:12

Latitude (centered)
7.250°

Longitude (East)
327.336°

Spacecraft altitude
277.4 km (172.4 miles)

Original image scale range
56.6 cm/pixel (with 2 x 2 binning) so objects ~170 cm across are resolved

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50 cm/pixel and North is up

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Equirectangular

Emission angle
12.4°

Phase angle
52.0°

Solar incidence angle
41°, with the Sun about 49° above the horizon

Solar longitude
315.5°, Northern Winter

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North azimuth:  97°
Sub-solar azimuth:  328.5°
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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.