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NASA's Mars Reconnaissance Orbiter has revealed that movement in sand dune fields on the Red Planet occurs on a surprisingly large scale, about the same as in dune fields on Earth.
This is unexpected because Mars has a much thinner atmosphere than Earth, is only about one percent as dense, and its high-speed winds are less frequent and weaker than Earth's.
For years, researchers debated whether sand dunes observed on Mars were mostly fossil features related to past climate, rather than currently active. In the past two years, researchers using images from Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera have detected and reported sand movement.
Now, scientists using HiRISE images have determined that entire dunes as thick as 200 feet (61 meters) are moving as coherent units across the Martian landscape. The study was published online today by the journal Nature.
Back-and-forth blinking of the below two-image animation shows movement of ripples covering a sand dune on Mars. The images are part of a study published by Nature on May 9, 2012, reporting movement of Martian sand dunes at about the same flux (volume per time) as movement of dunes in Antarctica on Earth.
The before-and-after images were taken 15 weeks apart by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The scale bar is 85 meters (279 feet). The site is part of a dune field inside the summit caldera of Nili Patera, an ancient volcano, at 8.7 degrees north latitude, 67.3 degrees east longitude.