[meteorite-list] NASA Finds Evidence Some Comets May Have Become Asteroids

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Sep 1 13:36:15 2005
Message-ID: <200509011735.j81HZAc00610_at_zagami.jpl.nasa.gov>

http://www.nasa.gov/centers/ames/research/exploringtheuniverse/comets.html

John Bluck
NASA Ames Research Center, Moffett Field, Calif.
Phone: 650/604-5026
E-mail: jbluck_at_mail.arc.nasa.gov

NASA Finds Evidence Some Comets May Have Become Asteroids
August 31, 2005

Some asteroids that have comet-like orbits may actually be comets that
have lost gases and other easily vaporized substances, according to a
NASA research team.

The team will present its findings at the American Astronomical
Society's Division for Planetary Sciences annual meeting in Cambridge,
England, on Sept. 5.

"Several objects classified as asteroids have orbits that are
dynamically similar to those of comets," said Dale Cruikshank, an
astronomer at NASA Ames Research Center in California's Silicon Valley
and a member of the research team. These asteroids may be comets that
have lost gases and other materials by repeated passages through the
inner solar system, according to Cruikshank.

The team studied infrared light from 55 asteroids using NASA's Spitzer
Space Telescope to "better understand possible links between asteroids
and comets," according to the authors. In addition to co-author
Cruikshank, Joshua Emery who also works at NASA Ames and is an employee
of the SETI Institute, Mountain View, Calif. is the principal author;
and Jeffrey Van Cleve of Ball Aerospace, Boulder, Colo., is the other
co-author.

"The suggestion that some asteroids originated as comets has been made
before, but the new Spitzer Space Telescope observations provide the
first chance to really test this suggestion," Emery noted. "Most of the
objects observed in our program appear to be typical asteroids, but a
few have surface compositions and textures that are more similar to
comets," Emery added.

"The infrared light we are studying gives us information about the
composition and surface textures of solid bodies in the solar system."
Cruikshank said.

The research team reports that some of the asteroids have very
fine-grained surfaces. "We think this fine-graininess is a
characteristic of comets," Cruikshank explained.

The Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer
Space Telescope mission for NASA's Science Mission Directorate,
Washington. Science operations are conducted at the Spitzer Science
Center at the California Institute of Technology, also in Pasadena.
Caltech manages JPL for NASA.

For information on the Spitzer Space Telescope visit:

http://www.spitzer.caltech.edu/spitzer/

For high-resolution images of comets, please visit:

http://www.nasa.gov/centers/ames/multimedia/images/2005/comets1.html
Received on Thu 01 Sep 2005 01:35:10 PM PDT