[meteorite-list] Space Radar Provides a Taste of Comet Hartley 2

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 29 Oct 2010 12:34:54 -0700 (PDT)
Message-ID: <201010291934.o9TJYscN005023_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2010-358

Space Radar Provides a Taste of Comet Hartley 2
Jet Propulsion Laboratory
October 28, 2010

Exactly one week before the world gets a new look at comet Hartley 2 via
NASA's EPOXI mission, observations of the comet by the Arecibo Planetary
Radar in Puerto Rico have offered scientists a tantalizing preview.

"It kind of looks like a cross between a bowling pin and a pickle," said
EPOXI project manager Tim Larson of NASA's Jet Propulsion Laboratory in
Pasadena, Calif. "Only it's about 14-thousand-times larger and hurtling
through space at 23 miles per second." A new image is online at
http://www.naic.edu/~pradar/103P.

Scientists using Arecibo's massive radar dish began observations of
Hartley 2 on Oct. 24, just four days after the comet made its closest
approach to Earth since its discovery in 1986. (On Oct. 20, the comet
came within 17.7 million kilometers, or 11 million miles, of Earth). The
observations are scheduled to continue through Friday, Oct. 29.

During the Nov. 4 flyby, the cameras aboard the EPOXI mission spacecraft
will get within 700 kilometers (about 435 miles) of the comet.

"Observing comet Hartley 2 from the Earth with radar was like imaging a
6-inch spinning cucumber from 836 miles away," said Jon Giorgini, a
scientist at JPL and a member of the Arecibo team that imaged the comet.
"Even without all the data in, we can still make some basic assertions
about Hartley 2. Its nucleus is highly elongated and about 2.2
kilometers [1.4 mile] long, and it rotates around itself about once
every 18 hours. In addition we now know the size, speed and direction of
particles being blown off the comet, and we immediately forwarded all
this information to the EPOXI team."

Just what a celestial pickle means for the EPOXI mission remains to be
seen. Mission engineers and scientists are discussing the new findings
and what - if anything - they signify for the upcoming comet encounter.

Along with Giorgini, observations of comet Hartley 2 were led by Arecibo
Obervatory's John Harmon, with contributions by Mike Nolan and E. S.
Howell.

The name EPOXI itself is a combination of the names for the two extended
mission components: the extrasolar planet observations, called
Extrasolar Planet Observations and Characterization (EPOCh), and the
flyby of comet Hartley 2, called the Deep Impact Extended Investigation
(DIXI). The spacecraft will continue to be referred to as "Deep Impact."

JPL manages the EPOXI mission for NASA's Science Mission Directorate,
Washington. The University of Maryland, College Park, is home to the
mission's principal investigator, Michael A'Hearn. Drake Deming of
NASA's Goddard Space Flight Center, Greenbelt, Md., is the science lead
for the mission's extrasolar planet observations. The spacecraft was
built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.

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

DC Agle 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
agle at jpl.nasa.gov

2010-358
Received on Fri 29 Oct 2010 03:34:54 PM PDT