A NASA spacecraft, launched in 2005 January, that rendezvoused with Comet 9P/Tempel 1 in 2005 July. It released a 370-kg impactor which hit the comet's nucleus, producing a crater and ejecting dust and ice that was studied by the main flyby craft and ground-based telescopes, improving knowledge of the structure and composition of the nucleus. The probe was subsequently put on course to Comet 103P/Hartley which it flew past in 2010 October in the EPOXI mission.
http://deepimpact.umd.edu/ Official mission website.
Subjects: Astronomy and Astrophysics.