Deep Impact comet strike. Explosion (white) on the surface of the nucleus (grey) of the comet 9P/Tempel 1, after being struck by the Deep Impact impactor. The Deep Impact spacecraft launched a 360-kilogram impactor at the comet, which successfully struck it at over ten kilometres per second on 4th July 2005. The impact caused the ejection of a large amount of interior material. The mission was launched on 12 January 2005. It was designed to study the composition of a comet, as comets are relics from the formation of the solar system. As such, they can provide much information about its history and formation. This image was captured by the Deep Impact spacecraft.