Saturday, November 19, 2011

Rippling Dune Front in Herschel Crater

A rippled dune front in Herschel Crater on Mars moved an average of about two meters (about two yards) between March 3, 2007 and December 1, 2010, as seen in these images from NASA's Mars Reconnaissance Orbiter. Note that the pattern of ripples on the dune surface has changed completely between the two images. Herschel Crater is located just south of the equator in the cratered highlands.

This is one of several sites where the orbiter has observed shifting sand dunes and ripples. Previously, scientists thought sand on Mars was mostly immobile. It took the mission's High Resolution Imaging Science Experiment (HiRISE) to take sharp enough images to finally see the movement.

While dust is easily blown around the Red Planet, its thin atmosphere means that strong winds are required to move grains of sand.

Photo credit: NASA/JPL-Caltech/University of Arizona/JHUAPL

Notes: For an animated GIF file that shows the movement of the dune over time, see here. Also, for more pictures, including animated GIFs of shifting sand dunes in Herschel Crater, see PIA14877: Shifting Sand in Herschel Crater and PIA14879: Rippling Dune Front in Herschel Crater on Mars.

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