LRO: Lunar Reconnaissance Orbiter
LCROSS - Mission
"The Shepherding Spacecraft and Centaur rocket are launched together with another spacecraft called Lunar Reconnaissance Orbiter (LRO). All three are connected to each other for launch, but then http://lcross.arc.nasa.gov/mission.htm
the LRO separates about two hours after launch.
The Shepherding Spacecraft guides the Centaur rocket through multiple Earth orbits, each taking about 38 days. The rocket then separates from the Shepherding Spacecraft and impacts the Moon at more than twice the speed of a bullet, causing an impact that results in a big plume or cloud of lunar debris, and possibly water"