Japan's Kaguya lunar orbiter will end its nearly two-year mission when it collides with the moon at 1825 GMT on Wednesday. Observers in Asia and Australia may be able to spot a bright flash or plume of dust from the crash, and researchers will study its impact site to watch how radiation and micrometeoroids weather the newly exposed lunar soil over time.

Launched in September 2007, Kaguya, formerly known at SELENE, sought to shed light on the formation and evolution of the moon by studying its composition, gravitational field and surface characteristics.
Japanese probe set to crash into moon - space - 08 June 2009 - New Scientist