PSP_004242_1495 shows a central peak of a large, degraded impact crater in the Terra Sirenum region of the southern hemisphere. Central peaks form during crater formation when a particularly large impactor hits the surface.

The central peak visible here (about 2/3 of the way down the image) is interesting because it has some fluvial-like features on its south side. At lower resolution, these features appear to be channels with some connecting pits. At higher resolution (see subimage, approximately 500 meters across; 2000 x 3000, 6MB), the features appear to be troughs that are filled with dunes.

What is most interesting is the chain of pits that extends down the center of some of the troughs as seen in the subimage. It is possible that these pits are evidence of subsurface piping or hydrothermal activity. Piping occurs when subsurface water flows through soil, takes some soil with it, and causes the overlying ground to collapse. These fluvial-like features and the connected pits may have formed during a late stage of crater formation when temperatures were suitable for liquid water.
Written by: Kelly Kolb

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.