NASA's Deep Impact mission is the astronomical highlight of the year, because for the first time a probe will hit a comet to reveal the secrets of its interior. The Deep Impact probe releases 24 h befor the arrival at the target Tempel 1 the small "impactor" (370 kg) which predominantly consists of copper.
The Deep Impact mission is a six-year mission funded by NASA in November of 1999. The spacecraft launched at December 2004 with a Delta II Rocket from the Kennedy Space Center. On July 4, 2005 arrives the spacecraft at the comet.
Comets are composed of ice, gas and dust and are considered time capsules that hold clues about the formation and evolution of the solar system 4.5 billion years ago. Comet Tempel 1 was discovered in 1867 by Ernst Tempel. The comet orbiting the Sun every 5.5 years. This makes Tempel 1 a good target to study evolutionary change in the mantle, or upper crust. Scientists are eager to learn whether comets exhaust their supply of gas and dust to space or seal it into their interiors.
They would also like to learn about the structure of a comet's interior and how it is different from its dark surface. Especially the core of a comet is a little mystery.
Some scientist call comets “dirty snowballs” but newer research results point to that the core of a comet consists more rocks than ice.
The flyby spacecraft uses an X-band radio antenna to communicate to Earth as it also listens to the impactor on a different frequency. For most of the mission, the flyby spacecraft communicates through NASA's Deep Space Network.
A lot of ground and space based telescops (inclusive Hubble, XMM-Newton and Chandra) will observe this event.
Other comet missions was the european spacecraft Giotto and the current mission Rosetta. Further than the american space probe Stardust.
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