[meteorite-list] Comet Hartley 2 Leaves a Bumpy Trail (WISE)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 15 Jul 2011 09:11:44 -0700 (PDT)
Message-ID: <201107151611.p6FGBir2000510_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2011-210

Comet Hartley 2 Leaves a Bumpy Trail
Jet Propulsion Laboratory
July 14, 2011

New findings from NEOWISE, the asteroid- and comet-hunting portion of
NASA's Wide-field Infrared Survey Explorer mission, show that comet
Hartley 2 leaves a pebbly trail as it laps the sun, dotted with grains
as big as golf balls.

Previously, NASA's EPOXI mission, which flew by the comet on Nov. 4,
2010, found golf ball- to basketball-sized fluffy ice particles
streaming off comet Hartley 2. NEOWISE data show that the golf
ball-sized chunks survive farther away from the comet than previously
known, winding up in Hartley 2's trail of debris. The NEOWISE team
determined the size of these particles by looking at how far they
deviated from the trail. Larger particles are less likely to be pushed
away from the trail by radiation pressure from the sun.

The observations also show that the comet is still actively ejecting
carbon dioxide gas at a distance of 2.3 astronomical units from the sun,
which is farther away from the sun than where EPOXI detected carbon
dioxide jets streaming from the comet. An astronomical unit is the
average distance between Earth and the sun.

"We were surprised that carbon dioxide plays a significant role in comet
Hartley 2's activity when it's farther away from the sun," said James
Bauer, the lead author of a new paper on the result in the Astrophysical
Journal. An abstract of the scientific paper is online at
http://arxiv.org/abs/1107.2637 , with the option of downloading a full PDF.

JPL manages and operates the Wide-field Infrared Survey Explorer for
NASA's Science Mission Directorate, Washington. The principal
investigator, Edward Wright, is at UCLA. The mission was competitively
selected under NASA's Explorers Program managed by the Goddard Space
Flight Center, Greenbelt, Md. The science instrument was built by the
Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by
Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations
and data processing take place at the Infrared Processing and Analysis
Center at the California Institute of Technology in Pasadena. Caltech
manages JPL for NASA.

More information is online at http://www.nasa.gov/wise ,
http://wise.astro.ucla.edu and http://jpl.nasa.gov/wise .

Whitney Clavin (818) 354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin at jpl.nasa.gov

2011-210
Received on Fri 15 Jul 2011 12:11:44 PM PDT


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