LCROSS

LCROSS (Lunar Crater Observation and Sensing Satellite) was a lunar impactor designed to further investigate the presence of water ice at the lunar poles after its existence was suggested by the earlier Clementine and Lunar Prospector missions. It was only added as a fast-tracked companion to the LRO mission after that payload was bumped from a Delta II to the larger Atlas V.

LCROSS was mounted atop the Centaur upper stage which which it was put into a 37-day-period Earth polar orbit to impact at the Moon’s southern pole. The LCROSS shepherding spacecraft separated from the Centaur stage which impacted the Moon first, at Cabeus crater, throwing up a debris plume that LCROSS flew through and analysed. LCROSS then impacted in the same location shortly afterwards, creating a second debris plume. Although the first plume was smaller than NASA had expected, data was nonetheless collected that confirmed the presence of water ice.