Aeolian Playground in Smith Crater
Aeolian Playground in Smith Crater
PSP_006284_1145  Science Theme: Aeolian Processes
This image shows a dark dune field in Smith Crater. The dark color of the dunes indicates that they are probably made of basaltic sand, a dark volcanic rock that is common on Mars. This is in contrast to dunes on Earth, which are dominated by quartz, a rare mineral on Mars.

The dunes here are “transverse dunes” that, based on analogy with similar features on Earth, form by winds that blow in a direction perpendicular to the crests. However, Secondary ripples on top of the dunes are oriented at right angles; that indicates a second wind regime that has redistributed the sand after the original dunes formed. The multiple orientations of the dunes may be partly caused by their location within the crater, whose own topography can act to redistribute regional wind patterns.

The dark streaks on the lighter terrain outside of the dune field are interpreted as dust devil tracks, where mini-tornadoes reveal darker ground beneath the bright dust of the surface. Some long dust devil tracks are visible in the southern part of the dune field and climb onto the troughs of the transverse dunes. There are also a few faded tracks at the northern part of the dune field.

Written by: Circe Verba, Nathan Bridges  (16 April 2008)
Acquisition date
29 November 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
250.4 km (155.6 miles)

Original image scale range
50.1 cm/pixel (with 2 x 2 binning) so objects ~150 cm across are resolved

Map projected scale
50 cm/pixel

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Phase angle

Solar incidence angle
70°, with the Sun about 20° above the horizon

Solar longitude
354.7°, Northern Winter

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North azimuth:  98°
Sub-solar azimuth:  53.2°
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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.