NASA's Lunar Reconnaissance Orbiter, after a four day flight, successfully fired its rocket and slipped into lunar orbit. LRO will map the surface of the Moon in unprecedented detail, paving the way for astronauts to return to the Moon. LRO data will be used to pick the site of the first lunar base.
Some might assume the Moon was mapped before Apollo and question why it needs to be done again, especially since the Moon is essentially a dead, unchanging world. There are several aspects to answering that question, but it comes down to mission definition. Apollo was focused on relatively safe landing sites and short stays. That led to mapping centered on the Moon's equatorial regions. A lunar base, however, is about permanence and extended exploratory forays from that base. More factors come into play than during Apollo, and, therefore, a better data base is needed. LRO is intended to provide that.