Dawn in the Asteroid Belt
In 2007, NASA launched the Dawn spacecraft with a mission not to visit any of the main planets in the Solar System, but the Asteroid Belt. It arrived at Vesta – one of the first objects ever observed in the region – in July 2011 and was inserted into its orbit. The main mission of Dawn is to gather data from the largest bodies in the Asteroid Belt to give scientists on Earth a clearer picture of how the Solar System formed.
Dawn left Vesta in September 2012 and is due to reach the biggest object in the Asteroid Belt – the dwarf planet Ceres – in February 2015. It’s the first exploratory probe to be powered by ion propulsion, using three xenon ion thrusters, meaning it’s easily capable of making multiple insertions. In contrast, standard chemical propulsion limits spacecraft like the Voyager probes to only flybys on secondary targets.