Fascinating view from NASA’s Curiosity Mars Rover showing the downwind side of “Namib Dune,” which stands about 13 feet (4 meters) high.
The site is part of Bagnold Dunes, a band of dark sand dunes along the northwestern flank of Mars’ Mount Sharp.
The component images stitched together into this scene were taken with Curiosity’s Navigation Camera (Navcam) on Dec. 17, 2015, during the 1,196th Martian day, or sol, of the rover’s work on Mars. In late 2015 and early 2016, Curiosity is conducting the first up-close studies ever made of active sand dunes anywhere but on Earth. Under the influence of Martian wind, the Bagnold Dunes are migrating up to about one yard or meter per Earth year. The view spans from westward on the left to east-southeastward on the right. It is presented as a cylindrical perspective projection.
The downwind, or lee, side of the dunes displays textures quite different from those seen on other surfaces of the dunes. Compare this scene, for example, to a windward surface of nearby “High Dune” (at http://mars.nasa.gov/multimedia/images/?ImageID=7581) from three weeks earlier. As on Earth, the downwind side of a sand dune has a steep slope called a slip face. Sand grains blowing across the windward side of a dune become sheltered from the wind by the dune itself. The sand falls out of the air and builds up on the lee slope until it becomes steepened and flows in mini-avalanches down the face.
Science Mars Journal: Volume 3, Issue 1
Sources: NASA Press Release