Left: Vesta as seen by Hubble before Dawn, Right: and after
The Dawn spacecraft is preparing to leave the asteroid Vesta for its next exciting target: the dwarf planet Ceres. Departure is scheduled for Sept 4th:
Link — Dawn began its 3-billion-mile (5-billion kilometer) odyssey to explore the two most massive objects in the main asteroid belt in 2007. Dawn arrived at Vesta in July 2011 and will reach Ceres in early 2015. Dawn’s targets represent two icons of the asteroid belt that have been witness to much of our solar system’s history.
To make its escape from Vesta, the spacecraft will spiral away as gently as it arrived, using a special, hyper-efficient system called ion propulsion. Dawn’s ion propulsion system uses electricity to ionize xenon to generate thrust. The 12-inch-wide ion thrusters provide less power than conventional engines, but can maintain thrust for months at a time.