Barchan Pac-Man
Barchan Pac-Man
ESP_054515_1930  Science Theme: Aeolian Processes
Barchan sand dunes are common on Mars and often form vast dune fields within very large (tens to hundreds of kilometers) impact basins. The regions upwind of barchans are usually devoid of sandy bedforms, so if you were walking in a downwind direction, then the barchans would seem to appear out of nowhere.

As you walk downwind, you would notice the barchans link up (“joining arms”) and eventually slope into featureless sand sheets. We call this progression of dunes a “Herschel-type dune field” named after the first place this sequence was described: Herschel Crater.

But here is something interesting: a barchan dune filling the upwind portion of a small impact crater in a Pac-Man-like shape. This “dune-in-a-crater” is nearly at the highest extent of the field. It’s also probably a rare configuration, and over the next few tens of thousands of years the sand will be blown out of the crater. Enjoy it while it lasts!

Written by: Kirby Runyon (audio: Tre Gibbs)  (14 May 2018)
Acquisition date
14 March 2018

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
279.5 km (173.7 miles)

Original image scale range
55.9 cm/pixel (with 2 x 2 binning) so objects ~168 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
48°, with the Sun about 42° above the horizon

Solar longitude
143.2°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  14.6°
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Black & white is 5 km across; enhanced color about 1 km
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NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.