Categories: Mars

Mars Mesas Stripped of Sand, Forming Dunes: Amazing Images from HiRISE

There seems to be a never-ending flow of stunning images coming from the High Resolution Imaging Science Experiment (HiRISE) on board NASA’s Mars Reconnaissance Orbiter (MRO). In today’s high-resolution look at the Martian surface, large flat-topped hills (a.k.a. mesas) can be seen to be eroded by the Mars winds, stripping them of their material, creating sand dunes downwind. An incredible sight, it shows just how dynamic and powerful the Martian winds really are…

Imaged above the Hellespontus region of Mars, these fluid-like structures trailing across the surface are huge sand banks and sand dunes, built up after years of erosion from mesas upstream. The Mars winds have gradually stripped the large geological structures, allowing sand to build up as dunes in areas of calm. The curious crescent/droplet-shaped dune morphology indicates dominant winds blowing from west to east (left to right). As sand is carried from the mesa, it travels downstream. Where the winds begin to slack, possibly in large turbulent eddies; the suspended sand is dropped to allow dunes to grow.

The shapes of the Mars dunes bear a striking resemblance to barchan dunes, much like the ones found on Earth. The wind blows up the gentle slope of the dune, allowing sand to gradually build up. As the sand reaches a critical point, it collapses, forming a sharp slope on the downwind-facing side. Horn-like features are evident from above. In addition to the barchans, “seif”-like dunes are evident. Seifs are longitudinal stretches of sand parallel to wind direction. These are most obvious as they trail away from the mesas and stretch toward the clusters of barchan dunes.

See the entire region in a full-resolution projection.

These new images were captured on March 16th and resolve features to approximately 1.5 meters. At this level of resolution the small ripples in the wind blown sand can even be seen. To give an idea of scale, I’ve included a close up of one of the dunes. As annotated, the larger dunes are approximately 60 meters in length (from east to west) and around 40 meters in width.

Source: HiRISE

Ian O'Neill

[Follow me on Twitter (@astroengine)] [Check out my space blog: Astroengine.com] [Check out my radio show: Astroengine Live!] Hello! My name is Ian O'Neill and I've been writing for the Universe Today since December 2007. I am a solar physics doctor, but my space interests are wide-ranging. Since becoming a science writer I have been drawn to the more extreme astrophysics concepts (like black hole dynamics), high energy physics (getting excited about the LHC!) and general space colonization efforts. I am also heavily involved with the Mars Homestead project (run by the Mars Foundation), an international organization to advance our settlement concepts on Mars. I also run my own space physics blog: Astroengine.com, be sure to check it out!

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