Comet Tempel 1
Comet 9/P Tempel 1 was discovered in 1867 at the Observatoire de Marseille by the astronomer Ernst Wilhelm Tempel. Its orbit, very close to the ecliptic, has a period of 5.5 years around the Sun and lies between the orbits of Mars and Jupiter. The diameter of the comet is 6.5 km and its rotation period is 41 h. Comet Tempel 1 has been explored in detail by the NASA probe Deep Impact which sent an impactor to its surface on July 4, 2005. The impact led to the formation of a 30-m large crater and the massive ejection of dust, water, and HCN. Following the success of another cometary mission, the Stardust encounter of comet Wild 2 in 2004, NASA decided in 2007 to reorient the Deep Impact spacecraft for a new flyby of comet Tempel 1. The flyby successfully took place on February 15, 2011, with a closest approach of less than 200 km, and the spacecraft recorded several tens of images of the surface, including the impact crater site.