Photos: Asteroid hunters leaving/returning to Earth

The Dawn spacecraft is built to travel on a 3.2 billion mile mission to visit the dwarf planet Ceres and asteroid Vesta, two of the largest bodies in the asteroid belt between Mars and Jupiter. Dawn is scheduled to arrive at Vesta in October 2011 and then reach Ceres in February 2015.

Ceres is known to have a primitive surface, water-bearing minerals, and possibly a very weak atmosphere and ice. When first discovered Ceres was called a planet but then was deemed to be an asteroid. It's promotion to a dwarf planet was overshadowed by the controversy over the demotion of Pluto from a planet to a dwarf planet.

Vesta is dry and its surface has been molded by volcanic activity. It has always been an asteroid.