This image taken from HiRISE instrument aboard the robotic Mars Reconnaissance Orbiter, shows a variety of different dune types in southern Lyot Crater in the Northern lowlands at 48.9 degrees north, on Mars. Image credit: NASA/JPL/University of Arizona
HiRISE has been carrying out a dedicated survey of sand dunes on Mars, determining whether and how fast the dunes move by observing repeatedly at intervals of Martian years. More than 60 sites have been monitored so far, showing that sand dunes from the equator to the poles are advancing at rates of up to 1 meter per Martian year.
Transverse dunes to the west grade into longitudinal dunes downwind to the east and barchans to the south, possibly because of local winds channeled by topography in the impact basin.
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