NASA EPOXI Flyby Reveals New Insights Into Comet Features

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DC Agle 818-393-9011
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Trent J. Perrotto 202-358-0321
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Lee Tune 301-405-4679
University of Maryland, College Park
ltune@umd.edu

NEWS RELEASE: 2010-373 Nov. 4, 2010

NASA EPOXI Flyby Reveals New Insights Into Comet Features

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2010-373&cid=release_2010-373

PASADENA, Calif. – NASA's EPOXI mission spacecraft successfully flew past comet Hartley 2 at
7 a.m. PDT (10 a.m. EDT) Thursday, Nov. 4. Scientists say initial images from the flyby provide new
information about the comet's volume and material spewing from its surface.

"Early observations of the comet show that, for the first time, we may be able to connect activity to
individual features on the nucleus," said EPOXI Principal Investigator Michael A'Hearn of the
University of Maryland, College Park. "We certainly have our hands full. The images are full of great
cometary data, and that's what we hoped for."

EPOXI is an extended mission that uses the already in-flight Deep Impact spacecraft. Its encounter
phase with Hartley 2 began at 1 p.m. PDT (4 p.m. EDT) on Nov. 3, when the spacecraft began to
point its two imagers at the comet's nucleus. Imaging of the nucleus began one hour later.

"The spacecraft has provided the most extensive observations of a comet in history," said Ed Weiler,
associate administrator for NASA's Science Mission Directorate at the agency's headquarters in
Washington. "Scientists and engineers have successfully squeezed world-class science from a re-
purposed spacecraft at a fraction of the cost to taxpayers of a new science project."

Images from the EPOXI mission reveal comet Hartley 2 to have 100 times less volume than comet
Tempel 1, the first target of Deep Impact. More revelations about Hartley 2 are expected as analysis
continues.

Initial estimates indicate the spacecraft was about 700 kilometers (435 miles) from the comet at the
closest-approach point. That's almost the exact distance that was calculated by engineers in advance
of the flyby.

"It is a testament to our team's skill that we nailed the flyby distance to a comet that likes to move
around the sky so much," said Tim Larson, EPOXI project manager at NASA's Jet Propulsion
Laboratory in Pasadena, Calif. "While it's great to see the images coming down, there is still work to
be done. We have another three weeks of imaging during our outbound journey."

The name EPOXI is a combination of the names for the two extended mission components: the
Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2,
called the Deep Impact Extended Investigation (DIXI). The spacecraft has retained the name "Deep
Impact." In 2005, Deep Impact successfully released an impactor into the path of comet Tempel 1.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, manages the
EPOXI mission for NASA's Science Mission Directorate. The spacecraft was built for NASA by Ball
Aerospace & Technologies Corp., in Boulder, Colo.

For more information about EPOXI, visit: http://www.nasa.gov/epoxi and http://epoxi.umd.edu/ .

For information about NASA and agency programs, visit: http://www.nasa.gov .

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