[meteorite-list] Astronomers Monitor Asteroid to Pass Near Mars

[Ron Baalke]

Grey Hautaluoma
Headquarters, Washington
202-358-0668
grey.hautaluoma-1 at nasa.gov 

D.C. Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle at jpl.nasa.gov 

Dec. 21, 2007
 
RELEASE : 07-284
 
Astronomers Monitor Asteroid to Pass Near Mars
 
WASHINGTON - Astronomers funded by NASA are monitoring the trajectory of
an asteroid estimated to be 164-feet wide that is expected to cross
Mars' orbital path early next year. Observations provided by the
astronomers and analyzed by NASA's Near-Earth Object Office at the Jet
Propulsion Laboratory in Pasadena, Calif., indicate the object may pass
within 30,000 miles of Mars at about 6 a.m. EST on Jan. 30, 2008.

"Right now asteroid 2007 WD5 is about half-way between the Earth and
Mars and closing the distance at a speed of about 27,900 miles per
hour," said Don Yeomans, manager of the Near Earth Object Office at JPL.
"Over the next five weeks, we hope to gather more information from
observatories so we can further refine the asteroid's trajectory."

NASA detects and tracks asteroids and comets passing close to Earth. The
Near Earth Object Observation Program, commonly called "Spaceguard,"
plots the orbits of these objects to determine if any could be
potentially hazardous to our planet.

Asteroid 2007 WD5 was first discovered on Nov. 20, 2007, by the
NASA-funded Catalina Sky Survey and put on a "watch list" because its
orbit passes near the Earth. Further observations from both the
NASA-funded Spacewatch at Kitt Peak, Ariz., and the Magdalena Ridge
Observatory in New Mexico gave scientists enough data to determine that
the asteroid was not a danger to Earth, but could potentially impact
Mars. This makes it a member of an interesting class of small objects
that are both Near Earth Objects and "Mars crossers."

Because of current uncertainties about the asteroid's exact orbit, there
is a 1-in-75 chance of 2007 WD5 impacting Mars. If this unlikely event
were to occur, it would be somewhere within a broad swath across the
planet north of where the Opportunity rover is.

"We estimate such impacts occur on Mars every thousand years or so,"
said Steve Chesley, a scientist at JPL. "If 2007 WD5 were to thump Mars
on Jan. 30, we calculate it would hit at about 30,000 miles per hour and
might create a crater more than half-a-mile wide." The Mars Rover
Opportunity is currently exploring a crater approximately this size.

Such a collision could release about three megatons of energy.
Scientists believe an event of comparable magnitude occurred here on
Earth in 1908 in Tunguska, Siberia, but no crater was created. The
object was disintegrated by Earth's thicker atmosphere before it hit the
ground, although the air blast devastated a large area of unpopulated
forest.

NASA and its partners will continue to track asteroid 2007 WD5. For more
information, visit:

http://neo.jpl.nasa.gov/

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