EPOXI

Epoxi is a low-cost mission that will expand our knowledge of both cometary bodies and extrasolar planetary systems. Epoxi is an acronym for two other acronyms ((Extrasolar Planet Observation and Characterization (EpOCh) and Deep Impact eXtended Investigation (DIXI)). Its low cost is derived by the recycling of the Deep Impact spacecraft which successfully guided an impactor into comet Tempel 1 in July 2005.

Hartley 2 was chosen as EPOXI's destination after the initial target, comet Boethin, could not be found. Scientists theorize comet Boethin may have broken up into pieces too small for detection.

The EPOXI mission melds two compelling science investigations: the Extrasolar Planet Observation and Characterization and the Deep Impact Extended Investigation. Both investigations will be performed using the Deep Impact spacecraft.

In addition to investigating comet Hartley 2, the spacecraft will point the larger of its two telescopes at nearby exosolar planetary systems in late January 2008 to observe several previously discovered planetary systems outside our solar system. It will study the physical properties of giant planets and search for rings, moons and planets as small as three Earth masses. It also will look at Earth as though it were an exosolar planet to provide data that could become the standard for characterizing these types of planets.

The mission's closest approach to the small half-mile-wide comet will be about 620 miles. The spacecraft will employ the same suite of two science instruments the Deep Impact spacecraft used during its prime mission to guide an impactor into comet Tempel 1 in July 2005.

If EPOXI's observations of Hartley 2 show it is similar to one of the other comets that have been observed, this new class of comets will be defined for the first time. If the comet displays different characteristics, it would deepen the mystery of cometary diversity.

History

Deep Impact was launched on January 12, 2005. The spacecraft travelled to comet Tempel 1 and deployed an impactor that was essentially "run over" by the nucleus of Tempel 1 on July 4, 2005. In December 2007, Deep Impact was re-christened EPOXI.

Mission controllers at JPL began directing EPOXI towards Hartley 2 on November 1, 2007. They commanded the spacecraft to perform a three-minute rocket burn that changed the spacecraft's velocity. EPOXI's new trajectory sets the stage for three Earth flybys, the first on Dec. 31, 2007. This places the spacecraft into an orbital "holding pattern" until time for the optimal encounter of comet Hartley 2 in 2010.

NASA approved the retargeting of the EPOXI mission in December 2007 for a flyby of comet Hartley 2 on October 11, 2010.

JPL manages EPOXI for NASA's Science Mission Directorate, Washington. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation, Boulder, Colorado, USA.

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Updated: Sunday 13th, April, 2008

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