Saturday, August 21, 2010

Martian Zambonis?

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!

Photo credit: NASA/JPL/University of Arizona

Note: This location is on the border between Planum Australe and Terra Cimmeria; the closest named feature is Jeans Crater.

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