From NASA:

On the moon we will develop technologies to survive in the infinite frontier of space, because the moon presents the same challenges we will encounter throughout the universe: harmful radiation, electrified dust, and extreme temperatures.

Just as a scout finds the safest way for expeditions on Earth, NASA will first send a robotic scout, called the Lunar Reconnaissance Orbiter (LRO), to gather crucial data on the lunar environment that will help astronauts prepare for long-duration lunar expeditions.

LRO’s launch date is scheduled for no earlier than June 17, 2009. The spacecraft will spend at least a year in a low polar orbit approximately 50 kilometers (31 miles) above the lunar surface, while its seven instruments find safe landing sites, locate potential resources, characterize the radiation environment, and test new technology.

The LRO blasted off on an Atlas V rocket on Thursday, June 18, at 4:32 p.m. CDT:

It will reach the moon on Tuesday, June 23, at 4:43 a.m. CDT.