Lunar Prospector
This crater became of interest to scientists when the Lunar Prospector detected unusually high concentrations of hydrogen on the floor of this and other nearby craters using a neutron spectrometer. The floor of this crater is kept in permanent shadow from the Sun, and thus maintains a temperature below . Thus the floor forms a cold trap, and any molecules of water that wander into the crater from cometary impacts can deposit on the floor and remain there almost permanently. The instruments on board Lunar Prospector gave a concentration of about 146 ppm of hydrogen, compared to 50 ppm for the average lunar surface.