Recycled NASA Spacecraft On Target for Comet Flyby

As a European comet probe prepares to swing by an asteroid this weekend, a recycled NASA spacecraft is headed for its own cosmic rendezvous with a comet.  

NASA's Deep Impact/Epoxi probe is zooming toward the Comet Hartley 2 and is expected to fly past the icy wanderer on Nov. 4. But first, the spacecraft — which originally flew to a different comet in 2005 — had to return to Earth briefly to nab a speed boost, NASA officials said.

The Epoxi spacecraft flew past Earth on June 27 taking advantage of the planet's gravitational force to increase its speed for the journey to Comet Hartley 2.

On Saturday, the European Space Agency's Rosetta space probe will fly by the previously-unvisited asteroid Lutetia. The spacecraft will take the first ever close-up photos of the space rock, while traveling on its current path to its main target, the comet 67P/Churyumov-Gerasimenko.

Members of the Epoxi team at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., are currently analyzing data returned from the Earth flyby in order to refine the spacecraft trajectory estimates in preparation for the probe's comet visit.

The Epoxi spacecraft was originally built as the mother ship for NASA's Deep Impact mission which intentionally crashed a probe into comet Tempel 1 in 2005 to determine the object's composition [Photos of the comet crash.]

During the recent Earth flyby, the Epoxi probe was not expected to snap any photos of Earth, the mission's principal investigator Michael A'Hearn, of the University of Maryland, told SPACE.com. 

Because the flyby was so different than what scientists expect at Comet Hartley 2, the probe also couldn't use the short flyby as a dress rehearsal for the actual comet observation campaign, he added.

"Coupled with the very different flyby speed and the huge difference between Earth and a comet for autonomous navigation, a dress rehearsal would not be a very valuable test," A'Hearn said.

Epoxi's actual observation campaign for Comet Hartley 2 will last three months, with the closest approach lasting just one day — Nov. 4, A'Hearn said.

On flyby day, Epoxi will zip past the comet and observe it with all three of the spacecraft's instruments (two telescopes with digital imagers and an infrared spectrometer).

Epoxi is an extended, unmanned mission of the Deep Impact space probe. Its name is derived from its dual science investigations — Deep Impact Extended Investigations (DIXI) and the Extrasolar Planet Observation and Characterization (EPOCh).

The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., in Boulder, Colo. JPL manages Epoxi for NASA's Science Mission Directorate in Washington, D.C. The University of Maryland is the principal investigator institution.

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