Sand Dunes on Mars Shift From Season to Season

Mars’ gravity makes it an amazing place to find some of the biggest landscapes in the solar system. Those would include the solar system’s biggest sand dune – one that resides in Russell crater. Now, a team of scientists led by Dr. Cynthia Dinwiddie noticed something unique about the sides of this massive dune. Occasionally gullies form along its surface. Dr. Dinwiddie’s novel explanation for this phenomena – boulders of CO2 rolling down the dune’s surface.

This isn’t the first time the gullies have been observed: “For over two decades, planetary scientists have had many ideas about how and when very long, narrow gullies formed on frost-affected sand dunes on Mars” Dr. Dinwiddie says. Explanations for those gullies mostly involve some sort of CO2 ice or water ice.

MRO Image showing downhill gullies that formed on Mars.Credit: NASA / JPL-Caltech / Univ. of Arizona

There were two key features of the dune that led to a possible explanation of the gullies. The first was that changes to the gullies were actively happening to the dune since observation began, which ran contrary to the original theory that they had been in place from time immemorial. The second was that there were ...