Deep Impact impactor. Image 2 of 3. Illustration of the Deep Impact impactor about to hit the surface of the nucleus of comet Tempel 1. The 500 kilogram impactor, travelling at 10 kilometres per second, will blast a large crater in the comet and eject material into space. Sensors on a related space probe (not seen) will monitor the explosion. The material inside the comet will be unchanged since the beginning of the solar system 5 billion years ago. This will provide information about the solar system's history. This NASA mission is due for launch in January 2004. For a sequence showing the impact, see images R250/139-141.