WISE Captures Key Image Of Comet Mission's Destination

WISE's infrared vision will allow the telescope to get a new estimate
of the size of the comet's nucleus, or core, as well as a more
thorough look at the sizes of dust particles that surround it. This
information, when combined with what EPOXI finds as it gets closer to
Hartley 2, will reveal how the comet has changed over time.

The WISE image is available at:

http://www.nasa.gov/mission_pages/WISE/multimedia/gallery/pia13438.html

On Nov. 4, the EPOXI mission, which uses the already "in flight" Deep
Impact flyby spacecraft, will reach its closet approach to Hartley 2.
The spacecraft will examine the dusty, icy body in detail as it flies
by, providing the best, extended view of a comet in history. WISE and
several other ground- and space-based telescopes are participating in
the viewing, working together to tackle mysteries about our solar
system's origins that are frozen inside comets.

For stargazers, opportunities to view the comet are possible
throughout October. On Wednesday, Oct. 20, Hartley 2 will reach its
closest approach to Earth since it was discovered in 1986. The comet
will be approximately 11 million miles away and should be visible
with the naked eye near the constellation Perseus if viewed in dark
skies. Observers will need binoculars or telescopes from urban areas
in the Northern Hemisphere. Southern Hemisphere stargazers can see
the comet later in the month.

WISE captured its view of the comet during an ongoing scan of the sky
in infrared light. The mission has been busy cataloging hundreds of
millions of objects, from comets to distant, powerful galaxies. In
late September, it used up its frozen cryogen coolant as expected and
began a new phase of its survey. Called the NEOWISE Post-Cryogenic
Mission, it primarily focuses on finding additional asteroids and
comets. To date, the WISE mission has observed more than 150,000
asteroids and 110 comets, including Hartley 2.

"Astronomers can reference our catalog to get detailed infrared data
about their favorite asteroid or comet," said Amy Mainzer, the
principal investigator of NEOWISE at JPL. "Space missions can also
use our observations for more information on their targets, as EPOXI is doing."

WISE's view of Hartley 2 was taken on May 10, 2010. It gives
astronomers a unique look at the comet, complementing what other
telescopes can see. Because WISE scanned the whole sky, it captured
the most extensive view of Hartley 2's trail, the dusty path left by
the comet on its repeated journey around the sun.

Bauer said, "We want to know how the comet behaves as it comes toward
the sun and out of deep freeze. The WISE image is one critical puzzle
piece of many that will give a comprehensive view of the behavior of
the comet through the time of the encounter."

The comet started to show signs of activity in the spring, spitting
out gas and dust. By July, there were clear jets of gas. "Comparing
the dust early on to what we see later with EPOXI helps us understand
how the activity started on Hartley 2," said Michael A'Hearn, the
principal investigator of EPOXI at the University of Maryland in College Park.

The term EPOXI is a combination of the names for the two extended
mission components: the Extrasolar Planet Observations and
Characterization (EPOCh), and the Hartley 2 flyby, called the Deep
Impact eXtended Investigation (DIXI). The name NEOWISE comes from
combining WISE and the acronym for near-Earth object, NEO.

For more information about EPOXI, visit:

http://www.nasa.gov/epoxi

http://epoxi.umd.edu/

For more information about WISE, visit:

http://www.nasa.gov/wise

http://wise.astro.ucla.edu/

Source: NASA

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