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Asteroids and Comets
.2 min read

NASA EPOXI Flyby Reveals New Insights Into Comet Features

Jet Propulsion Laboratory https://www.jpl.nasa.gov/ Nov. 4, 2010
This image montage shows comet Hartley 2 as NASA's EPOXI mission approached and flew under the comet. The images progress in time clockwise, starting at the top left.› Full image and caption
Credit: NASA/JPL-Caltech/UMD
This montage shows the only five comets imaged up close with spacecraft. The comets vary in shape and size. Comet Hartley 2 is by far the smallest and has the most activity in relation to its surface area.› Full image and caption
Credit: NASA/JPL-Caltech/UMD
This image shows many features across the comet's surface. The length of the comet is equal to the distance between the Capitol building and the Washington Monument in Washington. There are two obvious regions of jet activity associated with rough terrain.› Full image and caption
Credit: NASA/JPL-Caltech/UMD
This enhanced image shows jets and where they originate from the surface of comet Hartley 2. There are jets outgassing from the sunward side, the night side, and along the terminator -- the line between the two sides.› Full image and caption
Credit: NASA/JPL-Caltech/UMD
In the upper panel, small images of the comet are specially filtered to show only carbon dioxide, or evaporated dry ice, as a function of time. The lower panel is a graph showing the variation of total brightness.› Full image and caption
Credit: NASA/JPL-Caltech/UMD
These three pairs of images from NASA's EPOXI mission demonstrate that a dust jet and gaseous carbon dioxide are being released from comet Hartley 2 at the same time, and from the same location on the comet.› Full image and caption
Credit: NASA/JPL-Caltech/UMD

Scientists say initial images from today's flyby of comet Hartley 2 provide new information about the comet's volume and material spewing from its surface.

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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News Media Contact

DC Agle

Jet Propulsion Laboratory, Pasadena, Calif.

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Trent Perrotto

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301-405-4679

ltune@umd.edu

2010-373

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