[meteorite-list] Comet Found Hiding in Plain Sight By Spitzer Spacecraft

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 11 Sep 2013 12:31:35 -0700 (PDT)
Message-ID: <201309111931.r8BJVZ4U016706_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2013-274

Comet Found Hiding in Plain Sight
Jet Propulsion Laboratory
September 10, 2013

For 30 years, a large near-Earth asteroid wandered its lone, intrepid
path, passing before the scrutinizing eyes of scientists armed with
telescopes while keeping something to itself. The object, known as Don
Quixote, whose journey stretches to the orbit of Jupiter, now appears to
be a comet.

The discovery resulted from an ongoing project coordinated by
researchers at Northern Arizona University, Flagstaff, Ariz., using
NASA's Spitzer Space Telescope. Through a lot of focused attention and a
little luck, they found evidence of comet activity, which had evaded
detection for three decades.

The results show that Don Quixote is not, in fact, a dead comet, as
previously believed, but it has a faint coma and tail. In fact, this
object, the third-biggest near-Earth asteroid known, skirts Earth with
an erratic, extended orbit and is "sopping wet," said David Trilling of
Northern Arizona University, with large deposits of carbon dioxide and
presumably water ice. Don Quixote is about 11 miles (18 kilometers) long.

"This discovery of carbon dioxide emission from Don Quixote required the
sensitivity and infrared wavelengths of the Spitzer telescope and would
not have been possible using telescopes on the ground," said Michael
Mommert, who conducted the research at the German Aerospace Center,
Berlin, before moving to Northern Arizona University. This discovery
implies that carbon dioxide and water ice might be present on other
near-Earth asteroids, as well.

The implications have less to do with a potential impact, which is
extremely unlikely in this case, and more with "the origins of water on
Earth," Trilling said. Impacts with comets like Don Quixote over
geological time may be the source of at least some of it, and the amount
on Don Quixote represents about 100 billion tons of water -- roughly the
same amount that can be found in Lake Tahoe, Calif.

Mommert presented the results at the European Planetary Science Congress
in London on Sept. 10.

Read the full news release from Northern Arizona University at
http://news.nau.edu/nau-led-teams-discovers-comet-hiding-in-plain-sight/ .

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer
mission for NASA's Science Mission Directorate, Washington. Science
operations are conducted at the Spitzer Science Center at the California
Institute of Technology in Pasadena. Data are archived at the Infrared
Science Archive housed at the Infrared Processing and Analysis Center at
Caltech. Caltech manages JPL for NASA. For more information about
Spitzer, visit http://spitzer.caltech.edu and http://www.nasa.gov/spitzer .

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

2013-274
Received on Wed 11 Sep 2013 03:31:35 PM PDT