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This HiRISE image (PSP_002296_1215), near the southeast rim of Peneus Patera crater, is marked by depressions in the mantle with scalloped edges. Several of the depressions have apparently coalesced together.
These features are most commonly found at approximately 55 degrees north and south latitude. Their presence has led to hypotheses of the removal of subsurface material, possibly interstitial ice by sublimation (evaporation).
Steep scarps consistently face the south pole while more gentle slopes face in the direction of the equator. This is most likely due to differences in solar heating.
A polygonal pattern of fractures, commonly associated with "scalloped terrain," can be found on the surface surrounding and within the depressions. The fractures indicate that the surface has undergone stress that may have been caused by subsidence, desiccation, or thermal contraction.
Scallop formation is believed to be an ongoing process at the present time.
Acquisition date: 1 January 2007
Local Mars time: 4:01 PM
Degrees latitude (centered): ):-58.0°
Degrees longitude (East): 53.7°
Range to target site: 250.7 km (156.7 miles)
Original image scale range: 50.2 cm/pixel (with 2 x 2 binning) so objects ~150 cm across are resolved
Map-projected scale: 50 cm/pixel and north is up
Emission angle: 5.7°
Phase angle: 73.8°
Solar incidence angle: 78°, with the Sun about 12° above the horizon
Solar longitude: 170.9°, Northern Summer
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.