Discovered in 1867 by Ernst Tempel, Tempel 1 is a short-period comet, meaning that it moves around the sun in an elliptical orbit between Mars and Jupiter and can be sighted every six or so years. Photos shot by the Deep Impact probe as it awaited its suicidal collision revealed the comet's surface for the first time. Scientists said it appears to have a soft, dusty surface with crater-like features. Trapped ice seems to be below the surface, possibly containing the primordial ingredients of the solar system, said Deep Impact co-investigator Pete Schultz.