[meteorite-list] WISE Mission Spots 'Horseshoe' Asteroid (2010 SO16)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun, 10 Apr 2011 14:43:16 -0700 (PDT)
Message-ID: <201104102143.p3ALhHDb026651_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2011-112

WISE Mission Spots 'Horseshoe' Asteroid
Jet Propulsion Laboratory
April 08, 2011

An asteroid recently discovered by NASA's Wide-field Infrared Survey
Explorer (WISE) may be a bit of an oddball. Most near-Earth asteroids --
NEAs for short -- have eccentric, or egg-shaped, orbits that take the
asteroids right through the inner solar system. The new object,
designated 2010 SO16, is different. Its orbit is almost circular such
that it cannot come close to any other planet in the solar system except
Earth.

However, even though the asteroid rides around with Earth, it never gets
that close.

"It keeps well away from Earth," said Apostolos "Tolis" Christou, who,
together with David Asher of the Armagh Observatory in Northern Ireland,
analyzed the orbit of the body after it was discovered in infrared
images taken by WISE. "So well, in fact, that it has likely been in this
orbit for several hundred thousand years, never coming closer to our
planet than 50 times the distance to the moon."

The asteroid is one of a few that trace out a horseshoe shape relative
to Earth. As the asteroid approaches Earth, the planet's gravity causes
the object to shift back into a larger orbit that takes longer to go
around the sun than Earth. Alternately, as Earth catches up with the
asteroid, the planet's gravity causes it to fall into a closer orbit
that takes less time to go around the sun than Earth. The asteroid
therefore never completely passes our planet. This slingshot-like effect
results in a horseshoe-shaped path as seen from Earth, in which 2010
SO16 takes 175 years to get from one end of the horseshoe to the other.

"The origins of this object could prove to be very interesting," said
Amy Mainzer of NASA's Jet Propulsion Laboratory, Pasadena, Calif., the
principal investigator of NEOWISE, which is the asteroid- and
comet-hunting portion of the WISE survey mission. "We are really excited
that the astronomy community is already finding treasures in the NEOWISE
data that have been released so far."

NEOWISE finished its one complete sweep of the solar system in early
February of this year. Data on the orbits of asteroids and comets
detected by the project, including near-Earth objects, are catalogued at
the NASA-funded International Astronomical Union's Minor Planet Center,
at the Smithsonian Astrophysical Observatory in Cambridge, Mass.

A full story from the Armagh Observatory, including animations, is
online at http://www.arm.ac.uk/press/2011/aac_horseshoe_orbit.html.

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

2011-112
Received on Sun 10 Apr 2011 05:43:16 PM PDT