This image shows large sand dunes in the North Polar sand sea on Mars. It is one of a series of repeat images of the same dunes, taken at different times, in order to determine the type and extent of changes in the dunes over time.
Dunes tend to migrate slowly on Earth under continuous wind regimes (on the order of several to tens of meters per year), and we are just starting to verify movement on Martian dunes with these repeat HiRISE images.
In addition to migration of the dune, we will also use these repeat images to look for changes in the dune shape and avalanches down the slip face. Analyzing these changes will help us better understand the interaction between the atmosphere and the surface of Mars.
Photo credit: NASA/JPL/University of Arizona