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Artist impression of the Deep Impact Spacecraft being utilized on the EPOXI mission.

This close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument.

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Artist impression of the Deep Impact Spacecraft being utilized on the EPOXI mission.NASA/JPL-Caltech

This close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument.NASA/JPL-Caltech/UMD

Mission name: EPOXI

Deep Impact Extended Investigation (DIXI) and Extrasolar Planet Observation and Characterization (EPOCh)

Two intriguing investigations -- One flight-proven spacecraft

Launch Date January 12, 2005
Arrival Date November 04, 2010
End DateSeptember 16, 2013
Mission TypeFlyby/Space Telescope
TargetComet/Extrasolar Planets

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Mission Overview
The EPOXI mission recycled the Deep Impact spacecraft, which had formerly visited comet Tempel 1, to visit a second comet, Hartley 2. The Nov. 4, 2010, flyby marked only the fifth time a comet had been visited by a spacecraft.

EPOXI recycled the Deep Impact spacecraft to complete two additional missions: the Deep Impact Extended Investigation (DIXI) and Extrasolar Planet Observation and Characterization (EPOCh). DIXI focused on a flyby of the comet, Hartley 2. Previously, Deep Impact had visited the comet Tempel 1. The EPOCh used Deep Impact’s photographic instruments to identify and study extrasolar planets.

Relevance to Astrobiology
Comets are ancient bodies of frozen ice and dust that formed beyond the orbit of the most distant planet. Studying comets can help astrobiologists understand the processes behind planet formation in our solar system, conditions that led to habitability on Earth, and the potential role of comets in delivering key ingredients for the origins of life.

Observations of extrasolar planets are essential in determining the potential habitability of worlds beyond our solar system. Data from EPOXI adds to a large and growing body of knowledge concerning the diversity of planets in the Universe and the conditions in which they form and evolve.

NASA Astrobiology Involvement
Numerous researchers supported by the NASA Astrobiology Program were involved in the analysis of data from EPOXI. This includes scientific teams studying comets as well as those focused on extrasolar planet research.

Mission news and discoveries

NASA's Deep Impact/EPOXI spacecraft flew past Earth on June 27, 2010, to get a boost from Earth’s gravity. It is now on its way to comet Hartley 2, depicted in this artist’s concept, with a planned flyby this fall.

Apply for "The PI Launchpad: From Science Idea to NASA Mission"September 25, 2019

The Hyperactivity and Dust Composition of the Comet Hartley 2August 13, 2018

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Major mission findings

This enhanced image, one of the closest taken of comet Hartley 2 by NASA's EPOXI mission, shows jets and where they originate from the surface. There are jets outgassing from the sunward side, the night side, and along the terminator.

November 04, 2010A Cometary Flyby

The Deep Impact spacecraft flew by Earth for its fifth time on Sunday, June 27, 2010, on the EPOXI mission. When EPOXI flew by comet Hartley 2 on Nov. 4, 2010, it was the fifth time humans saw a comet close-up.

Comet Hartley 2, captured by the NASA EPOXI mission between Nov. 3 and 4, 2010.

November 10, 2010Details of Hartley 2

EPOXI revealed that comet Hartley 2’s rocky ends spew out tons of golf-ball to basketball-size fluffy ice particles, while the smooth middle area is more like what was observed on comet Tempel 1 with water evaporating below the surface and percolating out through the dust.

June 15, 2011Water and Carbon Dioxide

EPOXI finds that strong activity in water release and carbon dioxide-powered jets does not occur equally in the different regions of Hartley 2.

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Mission Facts

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Nov. 4, 2010, image from the High-Resolution Instrument on NASA's EPOXI mission spacecraft shows part of the nucleus of comet Hartley 2. The sun is illuminating the nucleus from the right. A distinct cloud of individual particles is visible.

Recycle, Reuse, RecordEPOXI mission recycles Deep Impact spacecraft

EPOXI is a hybrid acronym of two science investigations: the Extrasolar Planet Observation and Characterization (EPOCh) and Deep Impact eXtended Investigation (DIXI). The spacecraft keeps its name, Deep Impact, while the mission is called EPOXI.

A Second CometEPOXI Flyby of Hartley 2

The Nov. 4, 2010, flyby marked only the fifth time a comet had been visited by a spacecraft.

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