Deep Impact was a mission to hit a comet with a hard, dense object at high speed, and then take pictures and gather other data of the impact site and the ejected material. The reason for such a study was to see what the interior of a comet—the oldest unaltered material in the solar system—could reveal about the origin of the planets, and to learn how to deal with a future comet that might be on a collision course with Earth. The space explorer mission was combined with a concentrated effort of ground-based and space-based telescopes to study the comet and observe the impact and its aftermath.