This image, taken with the Wide Angle Camera (WAC), provides a master class in Mercury surface features and the geologic processes that formed them. The image shows a portion of Rachmaninoff, a double-ring basin named for the early twentieth century Russian composer, pianist and conductor Sergei Rachmaninoff. In this region, we see the remnants of an inner peak ring, with hollows dusting the tops of the peaks in both the inner and outer rings. Also visible is the basin's main rim scarp beginning in the left corner of the image and extending to the southeast. The crater floor contains a number of regions of high-reflectance material, as well as polygonal valleys called graben (located near the top of the image, at the basin's center). Graben are formed by forces pulling apart the surface; these extensional forces are in contrast to the tectonic contraction we typically see all over Mercury and may be related to cooling of the smooth volcanic plains that cover the floor.
Date acquired: February 06, 2012
Image Mission Elapsed Time (MET): 237042001
Image ID: 1361459
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 25.53°
Center Longitude: 57.51° E
Resolution: 136 meters/pixel
Scale: This image is 238 km (148 miles) wide from left corner to right corner.
Incidence Angle: 37.9°
Emission Angle: 36.3°
Phase Angle: 74.2°
Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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