[FMO] Fwd: NEO News (12/28/07) Odds of Mars Impact Increase

From: Marco Langbroek <marco.langbroek@xxxxxxxxxx>
To: FMO lijst <fmo@xxxxxxxxxxxxx>
Date: Sat, 29 Dec 2007 12:55:47 +0100



-------- Originele bericht --------
Onderwerp: NEO News (12/28/07) Odds of Mars Impact Increase
Datum: Fri, 28 Dec 2007 17:26:36 -0800
Van: David Morrison <david.morrison@xxxxxxxx>
Aan: David Morrison <david.morrison@xxxxxxxx>

NEO News (12/28/07) Odds of Mars Impact Increase

Date Released: Friday, December 28, 2007
Source: Jet Propulsion Laboratory

Updated Dec. 28, 2007 -- Astronomers have identified asteroid 2007 WD
5 in archival imagery. With these new observations, scientists at
NASA's Near-Earth Object Program Office at the Jet Propulsion
Laboratory in Pasadena, Calif have refined their trajectory estimates
for the asteroid. Based on this latest analysis, the odds for the
asteroid impacting Mars on Jan. 30 are now 1-in-25 -- or about 4
percent.

Note from David Morrison: In case of a close pass (but a miss), it is
normal for the impact odds to increase before they drop to zero. This
is because there is a time, as knowledge of the orbit improves, when
the error ellipse (the uncertainty in the miss distance) shrinks
while the target (in this case Mars) remains within the ellipse. Thus
the change in odds of a hit from 1 in 75 to 1 in 25 does not mean it
will hit -- it still has a 96% chance of missing -- but it sure is
interesting! It would be even more "interesting" if the target were
Earth not Mars. Think about it.

-------------------------------

WASHINGTON - Astronomers funded by NASA are monitoring the trajectory
of an asteroid estimated to be 50 meters (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
(3 a.m. PST) on Jan. 30, 2008.

"Right now asteroid 2007 WD5 is about half-way between 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 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
located.

"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 exploring a crater approximately this size right
now.

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 and
will provide an update in January when further information is
available. For more information on the Near Earth Object program,
visit: http://neo.jpl.nasa.gov/.

An audio interview/podcast regarding 2007 WD5 is available at:
http://www.jpl.nasa.gov/multimedia/podcast/mars-asteroid-20071221/

A videofile related to this story is available on NASA TV and the
Web. For information and schedules, visit: http://www.nasa.gov/ntv.

send to a friend
--
+++++++++++++++++++++++++++++++++++++++++++

NEO News (now in its fourteenth year of distribution) is an informal
compilation of news and opinion dealing with Near Earth Objects
(NEOs) and their impacts. These opinions are the responsibility of
the individual authors and do not represent the positions of NASA,
Ames Research Center, the International Astronomical Union, or any
other organization. To subscribe (or unsubscribe) contact
dmorrison@xxxxxxxxxxxxx For additional information, please see the
website http://impact.arc.nasa.gov. If anyone wishes to copy or
redistribute original material from these notes, fully or in part,
please include this disclaimer.







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[FMO] Fwd: NEO News (12/28/07) Odds of Mars Impact Increase

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