Bright blue marks a deposit of chloride (salt) minerals in the southern highlands of Mars in this false-color image, which highlights mineral composition differences. The Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter made this observation. Researchers using THEMIS reported in March 2008 that they have found about 200 such deposits of chloride salts. Observations by THEMIS and other instruments orbiting Mars indicate that these deposits typically lie within topographic depressions. The salt deposits suggest that Mars was much wetter long ago. They point to places where water was once abundant, then evaporated, leaving the minerals behind.
This site lies at about 221 degrees east longitude and 38.8 degrees south latitude, within the rugged Terra Sirenum region of Mars. The view is a portion of an image taken by THEMIS on Dec. 11, 2003. The full image is at http://themis-data.asu.edu/img/I08831002?tab=1.
The scale bar is about 10 kilometers (6.2 miles). The black rectangle indicates the outline of a higher resolution view, available as PIA10247.
Image Credit: NASA/JPL-Caltech/Arizona State University/University of Hawaii
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