This image shows frost on a crater slope.  The white frost covers nearly the top side of the crater, while the bottom part appears reddish in color.

January 22, 2015

Why does HiRISE take so many repeat images of the same area? Repeat coverage actually serves a special purpose, such as detecting seasonal changes (frost deposition and sublimation) and temporal changes (dust devil tracks and avalanches.) These repeat images also give us a "sneak peek" of future pictures to determine any differences.

Such is the case for this observation which we took in June 2014, and covers a small 1-kilometer sized simple crater located in the Southern hemisphere. In this composite and enhanced image, the crater shows frost on all its south-facing slopes (e.g., the crater's north wall and southern ejecta). This image was taken in late Martian winter as Mars is heading into spring.

With a repeat image, we can now see any changes of the same crater. And what do you know: all the frost that was once present on the south-facing slopes of the crater are now gone, having sublimated and returned to the Martian atmosphere.

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.

Credits

NASA/JPL-Caltech/University of Arizona

ENLARGE

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