Tolstoj Basin and Nureyev Crater

The Tolstoj basin (355 km in diameter) can be seen at the bottom edge of the frame, its center filled with smooth plains and surrounded by a large region of low-reflectance ejecta. The fresh, bright-rayed crater Nureyev is visible near the limb.

This image was acquired as part of MDIS's limb imaging campaign. Once per week, MDIS captures images of Mercury's limb, with an emphasis on imaging the southern hemisphere limb. These limb images provide information about Mercury's shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's northern hemisphere.

Date acquired: November 21, 2013
Image Mission Elapsed Time (MET): 27346412
Image ID: 5238318
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: -4.37°
Center Longitude: 188.8° E
Resolution: 1015 meters/pixel
Incidence Angle: 14.6°
Emission Angle: 58.8°
Phase Angle: 63.2°

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

Pit in Tolstoj Basin

The Tolstoj basin is located in Mercury's southern hemisphere, and is 355 km (220 miles) in diameter. This oblique image shows an elongate pit inside Tolstoj, a basin whose floor appears to have been flooded by lavas. The pit lacks the raised rim of an impact crater, and may have formed when magma withdrew from a shallow chamber, causing an unsupported area of the surface to collapse. The low-angle lighting in this image hides the floor of the pit, making it appear much deeper than it actually is. The pit is aligned approximately north-south.

Date acquired: January 11, 2012
Image Mission Elapsed Time (MET): 234752446
Image ID: 1251011
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: -16.97°
Center Longitude: 198.1° E
Resolution: 99 meters/pixel
Scale: This image shows a field of view approximately 150 km (93 miles) across
Incidence Angle: 84.8°
Emission Angle: 58.6°
Phase Angle: 135.6°

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

Note: These types of pit craters are fairly commonplace on Mars; for example, see Crater and Skylight on Pavonis Mons and Dark Rimless Pits in the Tharsis Region. That similar features should be present on Mercury is, to me, not surprising at all.

Shakespeare Impact Basin

For Valentine's Day, it seems appropriate to feature Shakespeare basin, named for the English poet and playwright and author of a famous collection of sonnets, some focusing on love. "Shall I compare thee" to other large basins on Mercury? If so, check out Rembrandt, Tolstoj, Rachmaninoff and Beethoven.

This mosaic was assembled from eight images that were acquired as part of MDIS's high-resolution surface morphology base map. The surface morphology base map will cover more than 90% of Mercury's surface with an average resolution of 250 meters/pixel (0.16 miles/pixel or 820 feet/pixel). Images acquired for the surface morphology base map typically have off-vertical Sun angles (i.e., high incidence angles) and visible shadows so as to reveal clearly the topographic form of geologic features.

Date acquired: April 26 - 28, 2011
Image Mission Elapsed Time (MET): 212372542, 212415875, 212416002, 212459333, 212459461, 212459565, 212502921, 212503025
Image ID: 181841, 183945, 183946, 185952, 185953, 185954, 188123, 188124
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 48.5°
Center Longitude: 208° E
Resolution: 240 meters/pixel
Scale: Shakespeare basin has a diameter of 400 km (250 miles)
Incidence Angle: 73°
Emission Angle: 0.6°
Phase Angle: 75°

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