This image of Mars' south polar area shows an amazing series of elliptical rings. Could these have been made by a Zamboni on Mars driving around and around on the ice? No, of course not! But the answer in some ways more fun.

The ice caps on Mars are surrounded by a thick stack of layered deposits. HiRISE and other instruments have shown that these layers are composed of dusty ice. Imagine this stack of layers as a cake with alternating layers. Now someone comes and takes a big scoop out of the middle of the cake! While our first reaction might be to get mad at them for ruining the cake, take a moment to think what the pattern would look like: it would have rings going round and round the hole. This is what we are seeing in this image of Mars.

Some erosional process has scooped a big hole into the layered deposits. So, no Zamboni, but we do have giant scoops digging into layer-cakes of ice!
Written by: Laszlo P. Keszthelyi

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.