NASA Mars Picture of the Day: Dark Sand Dunes 03-18-2004

Mars Global Surveyor Mars Orbiter Camera

MGS MOC Release No. MOC2-669, 18 March 2004

NASA/JPL/Malin Space Science Systems

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
image shows a field of low-albedo (i.e., dark) sand
dunes in a crater in Noachis Terra. Dunes on Earth are usually
light while those on Mars are usually dark. This contrast
results from a difference in the mineral composition. Earth dunes
often contain abundant quartz, which appears light, while martian
dunes typically contain minerals and rock fragments abundant in
iron- and magnesium-rich minerals, which are usually dark. This
dune field is located
near 41.7°S, 319.8°W. The steeper slopes on these dunes,
known as slip faces, point toward the lower left (southwest),
indicating the dominant winds come from the northeast (upper right).
This picture covers an area about 3 km (1.9 mi) across.
Sunlight illuminates the scene from the upper left.

Malin Space Science Systems and the California Institute of Technology
built the MOC using spare hardware from the Mars Observer mission.
MSSS operates the camera from its facilities in San Diego, California.
The Jet Propulsion Laboratory’s Mars Surveyor Operations Project
operates the Mars Global Surveyor spacecraft with its industrial
partner, Lockheed Martin Astronautics, from facilities in Pasadena,
California and Denver, Colorado.