Steichen Impact Basin

The large, older crater featured in today's image is Steichen. At almost 200 km (124 mi.) across, Streichen is a complex impact basin, with a central peak ring that is partially buried by smooth crater floor deposits. Though much of the northwestern central peak ring is buried, one tiny, bright blue speck surrounded by a dark blue halo pokes up through the smooth floor deposits, hinting that hollows might be forming in a little patch of excavated low-reflectance material.

This image was acquired as part of MDIS's 8-color base map. The 8-color base map is composed of WAC images taken through eight different narrow-band color filters and covers more than 99% of Mercury's surface with an average resolution of 1 kilometer/pixel. The highest-quality color images are obtained for Mercury's surface when both the spacecraft and the Sun are overhead, so these images typically are taken with viewing conditions of low incidence and emission angles.

Date acquired: August 13, 2011
Image Mission Elapsed Time (MET): 221758501, 221758509, 221758503
Image ID: 628307, 628312, 628308
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filters: 9, 7, 6 (996, 748, 433 nanometers) in red, green, and blue
Center Latitude: -12.53°
Center Longitude: 78.18° E
Resolution: 623 meters/pixel
Scale: Steichen crater is 196 km (122 mi.) in diameter.
Incidence Angle: 48.3°
Emission Angle: 0.2°
Phase Angle: 48.2°

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington