Geological Chronicle
Shoemaker is an impact crater situated near the south pole of the Moon, within half a crater diameter of Shackleton. It lies south of Malapert, east of Haworth, and just west of Faustini. The formation spans 51.82 kilometers across, bounded by a circular, worn rim with small craters along its inner wall. Because sunlight never reaches the floor, the albedo of its interior surface remains unknown.
The crater interior remains in permanent shadow from the Sun, keeping floor temperatures below 100 K (−173 °C). Under these thermal conditions, the floor acts as a cold trap where water molecules from cometary impacts can deposit and remain almost permanently. Observations by Lunar Prospector's neutron spectrometer recorded 146 ppm of hydrogen on the floor, compared to 50 ppm for the average lunar surface.
The crater topography was measured at a resolution of 150 meters by irradiating it with 3.5-centimeter radar from the 70-meter Goldstone antenna and receiving echoes with two 34-meter antennae located 20 kilometers apart. On July 31, 1999, Lunar Prospector was deliberately crashed into the floor to determine if a plume of water vapor would be detected, but subsequent tests failed to confirm the presence of water.
Informally named Mawson after Antarctic explorer Douglas Mawson, the formation received its official name from the International Astronomical Union in honor of American astrogeologist Eugene Shoemaker. A portion of Shoemaker's remains traveled aboard Lunar Prospector when it impacted the crater floor, a deposition criticized by the Navajo Nation as a desecration of the venerated Moon.