This image is of a crater in Arabia Terra, which is a large swath of bright (high albedo) terrain in the Martian cratered uplands. The steep interior walls of the crater are covered with numerous slope streaks, thought to be caused by dust avalanches that strip away layers of dust to reveal a darker underlying surface.

Here, multiple generations of slope streaks are present. The most recent features appear the darkest, and they appear to gradually brighten over time as more dust is deposited from the thin Martian atmosphere. Causes of dust avalanches include small impact craters, rockfalls, and oversteepening of the surface as dust accumulates. This last mechanism is similar to the way in which snow-covered slopes in high mountain areas on Earth accumulate enough snow to become gravitationally unstable, leading eventually to avalanches.

Written by: Brad Thomson

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.