New Mexico Gov. Bill Richardson, a Democrat, touted an "Apollo program" -- referring to the 1960s effort that put men on the moon -- that would reduce dependence on foreign oil by more than half and reduce greenhouse gas emissions by 80 percent.

CNN: Have we reached the energy tipping point?

By observing the cloud of dust and gas kicked up by each impact, scientists knew they could obtain valuable data about the Moon's composition.

BBC: Nasa reveals new information about moon probes crash sites