The Dawn spacecraft might have a 3-billion-mile journey ahead of it, but that doesn't mean NASA engineers are rushing to get the trip started. The mission control team has been communicating with the craft since its September 27th launch, and this past weekend, the scientists finally fired up one of Dawn's three ion propulsion engines.

They ran the system for 27 hours, burning only a soda-can-sized portion of Dawn's xenon fuel, and the spacecraft passed all its tests. The first stop on the mission, in 2011, will be the asteroid Vesta. Then Dawn will move on to the dwarf planet Ceres in 2015.—Gregory Mone

(Image credit: NASA)