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Tracking an Impact
Tracking an Impact
25 Mar 2009
(Source: Sandia National Laboratories)

Sandia National Laboratories

Media contact:
Neal Singer, (505) 845-7078


We saw it coming: Asteroid monitored from outer space to ground impact

Sandians Mark Boslough and Dick Spalding watch it in real time

ALBUQUERQUE, N.M. -- Reports by scientists of meteorites striking Earth in
the past have resembled police reports of so many muggings -- the offenders
came out of nowhere and then disappeared into the crowd, making it difficult
to get more than very basic facts.

Now an international research team has been able to identify an asteroid in
space before it entered Earth's atmosphere, enabling computers to determine
its area of origin in the solar system as well as predict the arrival time
and location on Earth of its shattered surviving parts.

"I would say that this work demonstrates, for the first time, the ability of
astronomers to discover and predict the impact of a space object," says
Sandia National Laboratories researcher Mark Boslough, a member of the
research team.

Perhaps more importantly, the event tested the ability of society to respond
very quickly to a predicted impact, says Boslough. "In this case, it was
never a threat, so the response was scientific. Had it been deemed a threat
-- a larger asteroid that would explode over a populated area -- an alert
could have been issued in time that could potentially save lives by
evacuating the danger zone or instructing people to take cover."

The profusion of information in this case also helps meteoriticists learn
the orbits of parent bodies that yield various types of meteorites.

Such knowledge could help future space missions explore or even mine the
asteroids in Earth-crossing orbits, Boslough says.

The four-meter-diameter asteroid, called 2008 TC3, was initially sighted by
the automated Catalina Sky Survey telescope at Mount Lemmon, Ariz., on Oct.
6. Numerous observatories, alerted to the invader, then imaged the object.
Computations correctly predicted impact would occur 19 hours after discovery
in the Nubian Desert of northern Sudan.

According to NASA's Near Earth Object program, "A spectacular fireball lit
up the predawn sky above Northern Sudan on October 7, 2008."

A wide variety of analyses were performed while the asteroid was en route
and after its surviving pieces were located by meteorite hunters in an
intense search.

Researchers, listed in the paper describing this work in the March 26 issue
of the journal Nature, range from the SETI Institute, the University of
Khartoum, Juba University (Sudan), Sandia, Caltech, NASA Johnson Space
Center and NASA Ames, to other universities in the U.S., Canada, Ireland,
England, Czech Republic and the Netherlands.

Sandia researcher Dick Spalding interpreted recorded data about the
atmospheric fireball, and Boslough estimated the aerodynamic pressure and
strength of the asteroid based on the estimated burst altitude of 36

Searchers have recovered 47 meteorites so far -- offshoots from the
disintegrating asteroid, mostly immolated by its encounter with atmospheric
friction -- with a total mass of 3.95 kilograms.

The analyzed material showed carbon-rich materials not yet represented in
meteorite collections, indicating that fragile materials still unknown may
account for some asteroid classes. Such meteorites are less likely to
survive due to destruction upon entry and weathering once they land on
Earth's surface.

"Chunks of iron and hard rock last longer and are easier to find than clumps
of soft carbonaceous materials," says Boslough.

"We knew that locating an incoming object while still in space could be
done, but it had never actually been demonstrated until now," says Boslough.
"In this post-rational age where scientific explanations and computer models
are often derided as 'only theories,' it is nice to have a demonstration
like this."

Sandia is a multiprogram laboratory operated by Sandia Corporation, a
Lockheed Martin company, for the U.S. Department of Energy's National
Nuclear Security Administration. With main facilities in Albuquerque, N.M.,
and Livermore, Calif., Sandia has major R&D responsibilities in national
security, energy and environmental technologies, and economic


[Image 1:
Don't look back -- it may be gaining on you: Sandia's Mark Boslough
discusses aspects of asteroids (Photo by Randy Montoya)

[Image 2:
Dick Spalding examines the night sky (Photo by Randy Montoya)

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Last Updated: 30 Mar 2009