Just days after expressing “great confidence” that they had found the best possible target for next week’s planned crash into the moon, the Lunar Crater Observation and Sensing Satellite (LCROSS) mission team has retreated from its first choice. Yesterday, NASA quietly posted the targeting switch from crater Cabeus A to nearby Cabeus proper.
The goal of crashing LCROSS’s spent upper stage is to kick up any subsurface water ice into the view of the trailing LCROSS spacecraft. (The mission is only distantly connected to last week's much ballyhooed finding of molecular water on the lunar surface.) But continuing analysis of remote sensing from NASA’s Lunar Reconnaissance Orbiter was pointing to stronger signs of subsurface hydrogen—presumably in the form of water—in the permanent shadow inside Cabeus than in similarly cold shadow in Cabeus A, according to the NASA statement. At the same time, topographical observations from the orbiter and the Japanese orbiter Kaguya were showing that ground-based astronomers could after all glimpse impact ejecta through a gap in the high rim of Cabeus. Impact still will be as planned at 7:30 a.m. EDT on 9 October.