Evros Vallis and Nearby Craters
NASA/JPL/University of Arizona
Evros Vallis and Nearby Craters
PSP_003273_1675  Science Theme: Landscape Evolution
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This image shows part of Evros Vallis, one of the Martian valley networks.

These more ancient valley networks may have been eroded by flowing water during a warmer, wetter period of Martian history. Many dunes are visible along the valley floor, as well as throughout the scene and in a partially exhumed crater on the valley wall. There are multiple generations and orientations of dunes. Dune orientation reflects the dominant or prevailing wind direction. Multiple dune orientations indicate that this region has experienced different wind regimes.

An exhumed crater is one that likely formed a long time ago, was buried, and is now being re-exposed because the materials that originally covered it are being eroded away. The prominent crater on the valley wall as well as several other craters in this scene are thought to be partially exhumed.

The subimage shows a couple groups of secondary craters. Secondary craters are craters that form when ejecta from the primary crater hits the surface with enough energy to form another smaller crater. As seen in the subimage, secondary craters often form in clusters spatially, because ejecta thrown out of the primary crater impacts the surface near each other at approximately the same time.

Many potential secondary craters have have similar morphologies and have distinct, bright ejecta. This implies that these craters are relatively young and that their ejecta have yet to be covered by dust.

Written by: Kelly Kolb  (16 May 2007)

This is a stereo pair with PSP_003695_1675.
 
Acquisition date
08 April 2007

Local Mars time
15:41

Latitude (centered)
-12.616°

Longitude (East)
13.301°

Spacecraft altitude
262.3 km (163.0 miles)

Original image scale range
26.4 cm/pixel (with 1 x 1 binning) so objects ~79 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
7.5°

Phase angle
46.3°

Solar incidence angle
54°, with the Sun about 36° above the horizon

Solar longitude
215.3°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  356.8°
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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:
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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.