The Contour spacecraft (seen here in an artist depiction) will encounter at least two comets during its lifetime.


At 2:47 a.m. EDT this morning, the Applied Physics Laboratory's Contour comet probe launched from Cape Canaveral, Florida, aboard a Delta 7425 rocket en route to its elliptical, 109,000-kilometer apogee orbit around Earth. Contour (a contraction for Comet Nucleus Tour) will spend until August 15th in this parking orbit. On that date a solid-fuel rocket will put Contour in its intended solar orbit. This new path will range between the orbits of Venus and Mars, with a perihelion of 0.80 astronomical unit (120 million kilometers) and an aphelion of 1.35 a.u.

Three months after a swingby of Earth in August 2003, Contour will zip past Comet 2P/Encke. Another Earth flyby the following August will send Contour on an 18-month "backflip" across the inner solar system at an inclination of 12°. A second series of Earth flybys, concluding in February 2006, then sets up an encounter with Comet 73P/Schwassmann-Wachmann 3 in June 2006 and probably with a third comet — possibly 6P/d'Arrest — in 2008. NASA planners note that the mission design is so flexible that, given enough lead time, the spacecraft can be redirected to intercept an unexpected cometary visitor passing through the inner solar system.

The craft features a spectrometer to analyze the chemical composition of the comets as well as two high-resolution cameras. The mission is NASA's sixth Discovery mission, coming in with a budget of $159 million.

Contour was originally to launch on July 1st, but was delayed after engineers discovered a thin layer of dust on the solar panels. Engineers determined the culprit was simply "room dust" and quickly cleaned the craft.


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