NASA - Lunar Reconnaissance Orbiter (LRO)

NASA's Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Spacecraft are on their way to the moon atop the same Atlas V rocket, although they will use vastly different methods to study the lunar environment. LRO will go into orbit around the moon, turning its suite of instruments towards the moon for thorough studies. The spacecraft also will be looking for potential landing sites for astronauts.

LCROSS, on the other hand, will guide an empty upper stage on a collision course with a permanently shaded crater in an effort to kick up evidence of water at the moon's poles. LCROSS itself will also impact the lunar surface during its course of study.

Liftoff occurred at 5:32 p.m. EDT. Mission managers used the last launch opportunity due to storms surrounding the launch site.

via NASA - Lunar Reconnaissance Orbiter (LRO).