[meteorite-list] Asteroid Strike Ruled Out For 2014

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:29:50 2004
Message-ID: <200309031520.IAA23254_at_zagami.jpl.nasa.gov>

http://www.msnbc.com/news/960340.asp

Asteroid strike ruled out for 2014

After alert, further observations eliminate risk of collision
                 
By Alan Boyle
MSNBC
September 2, 2003

       After sounding the alarm about a kilometer-wide
asteroid, astronomers said Tuesday that further data eliminated
the possibility of a catastrophic collision in 2014. This week's
alert followed the up-and-down course that is typical for
observations of near-Earth objects.
       ASTEROID 2003 QQ47 was first observed on Aug. 24, and based
on limited data, experts at NASA's Jet Propulsion Laboratory
estimated as of early Tuesday that there was a tiny chance - 1 in
909,000 - that the space rock would smash into Earth on March 21,
2014.
       Observations gathered on Monday night, however, allowed
astronomers to plot the asteroid's orbital course more precisely. By
Tuesday evening, the risk for 2014 was eliminated. JPL said there was
still a 1-in-2.2 million chance that an impact could occur sometime in
the next century, but that is far below the "background risk" of a
catastrophic collision in any given year.
       "We have many asteroids that have residual risks," Paul Chodas, a
research scientist at JPL who specializes in calculating the orbits of
near-Earth objects. "This particular one was of interest because it is
fairly large, 1.3 kilometers [0.8 mile], and the predicted impact was only
10 years away. Combining those two factors, we raised it to some level
of concern."
       The rock was first observed by the Lincoln Near Earth Asteroid
Research Program, also known as LINEAR.
       At one time, the 2014 encounter was given a rare rating of 1 on the
Torino Scale of asteroid and comet threats. But based on the additional
observations, the Torino rating was reduced to zero by JPL as well as
the NEODyS asteroid-monitoring group in Italy.
       "We expect the impact possibilities to go to zero," Chodas said.
"That is the usual scenario."
       If a rock as big as 2003 QQ47 ever were to hit Earth, it could have
the effect of millions of Hiroshima-scale atom bombs. Such impacts are
thought to have contributed to mass extinctions, including the demise of
the dinosaurs 65 million years ago.
       
WHERE SPACE ROCKS COME FROM

       Asteroids are chunks of rock left over from the formation of the solar
system 4.5 billion years ago. Most are kept at a safe distance from the
Earth in the asteroid belt between Mars and Jupiter. But some
asteroids trace an orbit that crosses Earth's own.
       In the past several years, programs such as LINEAR have
upgraded scientists' asteroid-detecting capabilities to the point that
asteroid alerts are not all that unusual anymore. Astronomers currently
are tracking more than 600 near-Earth asteroids wider than a kilometer
- and there are likely hundreds more yet to be found. There are thought
to be many more smaller near-Earth objects that could create localized
damage in the event of a collision.
       JPL's Chodas emphasized that the process of tracking near-Earth
objects and refining their orbits can take days, weeks or months.
       "We never know orbits very accurately," he told MSNBC.com.
"This asteroid has been seen only for nine days, and here we're trying
to predict its position 10 years in the future. So there are many
uncertainties."
       
Received on Wed 03 Sep 2003 11:20:26 AM PDT