The NASA mission that intentionally crashed into the Moon in 2009 to search for water was LCROSS.
LCROSS—short for Lunar Crater Observation and Sensing Satellite—launched with the Lunar Reconnaissance Orbiter on June 18, 2009. Its target was the permanently shadowed lunar south-polar crater Cabeus, where scientists suspected that hydrogen might indicate buried water ice.
The mission used a two-stage impact. NASA first sent the spent Centaur upper stage into Cabeus on October 9, 2009, creating a debris plume. The LCROSS Shepherding Spacecraft flew through that plume, analyzed its contents, transmitted the data to Earth, and then struck the Moon itself about six minutes later.
NASA reported in November 2009 that the impact revealed water in the plume. LADEE studied the Moon’s thin atmosphere, GRAIL mapped its gravity field, and Clementine was an earlier lunar-mapping mission; none was the 2009 water-seeking impact mission.