Central peaks form when a large impact crater rebounds after the initial compression stage, lifting deep bedrock up into hills or mountains. Ritchey Crater is a large (more than 100 kilometer diameter), well-preserved impact crater in the southern highlands of Mars, south of Valles Marineris.

This HiRISE color image reveals a rich diversity of colors and textures in the central region of the crater. For example, the subimage shows several densely fractured outcrops of bedrock with a range of colors due to different rock types, partially covered by dark sand dunes.

In the middle of the area is medium-dark material that contains many bright rock fragments—perhaps breccia (broken up and randomly jumbled rocks). There are raised ridges—both straight and sinuous—which may mark fractures and channels that could have been indurated (hardened) by water-deposited minerals. The heat of the impact event could have driven hydrothermal circulation of water for many centuries.

The colors in this image are from the infrared, red, and blue-green filters, in which each color band is given a separate contrast stretch. In the subimage the colors were further enhanced in intensity to reveal more subtle variations. If a rover could land here, it would be able to study a treasure trove of diverse rocks and minerals and ancient environments.
Written by: Alfred

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: Image: NASA/JPL/University of Arizona

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.