THEMIS: Dunes engulfing hills and mesas

Dunes engulfing mesas in Arabia Terra (THEMIS_IOTD_20180320THEMIS Image of the Day, March 20, 2018. The bottom of this image shows the hills and mesas within the crater. The dunes at the top of the image are engulfing and covering the hills.

In some locations the hills are still a substantial obstacle to the wind. In these cases the wind is blowing sand up against the windward side, but the hill is causing chaotic wind flow around the hill and rather than depositing sand, the wind is actually removing sand on the leeward side of the hill.

With continued winds and sand movement the deposition of material will eventually build up along the leeward side of the hill and then engulf the hill on all sides.

Located in eastern Arabia is an unnamed crater, 120 kilometers (75 miles) across. The floor of this crater contains a large exposure of rocky material, a field of dark sand dunes, and numerous patches of what is probably fine-grain sand. The shape of the dunes indicate that prevailing winds have come from different directions over the years. (A false-color image of the dune field and background on its features is here.)

NASA’s Mars Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions.

Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all.

For the next several months the Image of the Day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dune fields. We hope you enjoy these images!

More THEMIS Images of the Day by geological topic.

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