Deep Impact is a NASA space probe designed to study the composition of the interior of the comet Tempel 1. At 5:52 UTC on July 4, 2005, one section of the Deep Impact probe successfully impacted the comet's nucleus, excavating debris from the interior of the nucleus. Photographs of the impact showed the comet to be more dusty and less icy than expected. The impact generated a large, bright dust cloud that obscured the hoped-for view of the impact crater.
Previous space missions to comets, such as Giotto and Stardust, were fly-by missions, only able to photograph and examine the surfaces of cometary nuclei from a distance. The Deep Impact mission was the first to eject material from a comet's surface.
