Barchan Dunes in Chasma Boreale
Barchan Dunes in Chasma Boreale
PSP_010169_2650  Science Theme: Aeolian Processes
This image shows dark sand dunes in Chasma Boreale. Chasma Boreale is a giant trough that cuts into the north polar ice cap for 570 kilometers (350 miles) forming a broad valley bordered by stacked layers of ice. A portion of the north polar ice cap is visible at the northern edge of the trough in the upper portion of the image.

Many dark toned sand dunes march down the trough under the wind's direction. The sand dunes visible here are barchan dunes. Barchan dunes are also commonly found on Earth, and are crescent-shaped with a steep slip face bordered by horns oriented in the downwind direction. Barchan dunes form by uni-directional winds and thus are good indicators of the dominant wind direction. In this case, the dunes indicate that the direction of the strongest winds are parallel to the chasma walls, roughly east to west. The dark material composing the dunes could be volcanic ash or is possibly dark sand eroding out of the polar layered materials.

Written by: Maria Banks  (19 November 2008)
Acquisition date
26 September 2008

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
319.0 km (198.3 miles)

Original image scale range
31.9 cm/pixel (with 1 x 1 binning) so objects ~96 cm across are resolved

Map projected scale
25 cm/pixel

Map projection

Emission angle

Phase angle

Solar incidence angle
67°, with the Sun about 23° above the horizon

Solar longitude
133.0°, Northern Summer

For non-map projected images
North azimuth:  121°
Sub-solar azimuth:  323.6°
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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.