Pastel colors swirl across Mars, revealing differences in the composition and nature of the surface in this false-color infrared image taken on May 22, 2009, by the Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter.
The image shows an area 31.9 kilometers (19.8 miles) by 88.3 kilometers (54.9 miles) in the southern highlands of Mars. It is a result of altering the orbit of Odyssey so that the spacecraft passes over the day side of Mars earlier in the afternoon, when the ground is warmer and thus emits more strongly in the infrared frequencies detected by THEMIS. Prior to beginning the slow shift in orbit on Sept. 30, 2008, Odyssey was looking down at ground where the local solar time was about 5 p.m. When the shift was completed, on June 9, 2009, the orbiter and camera were looking down at ground where the local solar time is about 3:45 p.m.
In the image, dark areas mark exposures of relatively cold ground with abundant bare rock, while warmer basaltic sand covers the light blue-green regions. Reddish areas likely have a higher silica content, due either to a different volcanic composition or to weathering.
Image Credit: NASA/JPL-Caltech/Arizona State University
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