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 (1 July 2009)
This is a stereo pair with ESP_013527_1070 .
More info and image formats at http://hirise.lpl.arizona.edu/ESP_013329_1070
Image: NASA/JPL/University of Arizona