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Los Alamos array detects large, bright meteor: Laboratory researcher joins
the search
LOS ALAMOS, N.M., Oct. 10, 1997 - Researchers at Los Alamos National
Laboratory were able to use an array developed to listen for clandestine
nuclear weapons tests to help locate a large meteor that flashed in the sky
Thursday afternoon above Southern New Mexico.
The object -- presumably a large, bright meteor known as a bolide -- was
seen in the skies Thursday at about 12:47 p.m. Witnesses said the object
was at least as bright as the full moon or as bright as the setting sun.
"The meteor made a huge sonic signal," said Doug ReVelle, a meteorologist
in Los Alamos' Atmospheric and Climate Sciences Group. "They heard it like
a freight train in El Paso."
Using data from Los Alamos listening stations originally set up to monitor
nuclear explosions, ReVelle and other researchers in Los Alamos'
Atmospheric and Climate Sciences Group analyzed the infrasonic signature
created when the meteor entered the atmosphere.
When a meteor enters the atmosphere -- or when a large explosion is
detonated -- it creates a sound or pressure wave that is below the range of
human hearing. This infrasonic wave travels through the atmosphere and can
be detected by special microphones that are set up in an array. By looking
at the time of arrival of the sounds at different stations and the
frequency of the infrasonic boom, researchers can pinpoint the location of
the source and the determine the amount of energy that created it.
"The data from our array puts the meteor 441 kilometers due south of Los
Alamos," said ReVelle. "We'll be looking for it in a location we've
identified near El Paso."
ReVelle will join researchers from Canada, the University of New Mexico and
Sandia National Laboratory on a search this weekend for any meteor
fragments that may have reached the ground.
"The object's infrasonic signature was equivalent to the explosive yield of
about 500 tons of TNT," ReVelle said. "That means the object was somewhere
around one half to three-quarters of a meter in diameter."
Thanks to the infrasound array at Los Alamos, researchers at the Laboratory
were able to narrow down the location where it may have landed pretty well.
In addition to searching for remains of the meteor -- which may have
exploded into tiny bits in the sky - the researchers will interview
witnesses about the object: how bright it was; what it sounded like.
The object created a brilliant light as it streaked toward Earth. Witnesses
in Santa Fe, Los Alamos, Albuquerque, El Paso and points in between saw the
object in the sky.
ReVelle and the others will search all weekend for the object and collect
other data as well.
"It could take weeks to find, but it could take a day or less, depending on
how lucky we get," ReVelle said.
Infrasonic waves are very low frequency sounds that exist somewhere in the
realm between hearing and meteorology, ReVelle said. The sounds are well
below the range of human hearing, which ends at about 30 hertz, but
actually can be detected as small changes in atmospheric pressure. If
someone had a barometer that was sensitive enough, that person would be
able to see fluctuations of several microbars when infrasonic waves arrive.
During the 1960s and early 1970s, before the rise of the satellite era, the
United States Air Force operated a network of stations to listen for
nuclear weapons tests. The listening stations were the nation's first line
of detection for nuclear explosions worldwide.
The four arrays of listening stations operated by Los Alamos are the only
infrasonic network left in full-time operation in the world. They can
detect meteors that are as small as a few centimeters in diameter. The
stations are useful because they can help validate other non-proliferation
and verification techniques, and they cost very little to operate and
maintain.
The Los Alamos stations, around since 1983, still are enlisted in the
nation's nuclear non-proliferation efforts, but have provided a way for
scientists to detect bolides, larger-than-average space debris that slams
into Earth's atmosphere and creates brilliant fireballs in the sky.
Each year a number of large meteors enter the atmosphere and are detected
by the Los Alamos array. Some meteors are tens of meters in diameter.
ReVelle said each year about 10 meteors that are two meters in diameter -
with an energy equivalent of a one-kiloton blast - enter the atmosphere.
Most burn up or explode in brilliant flashes. Some hit the ground.
For this weekend's search, ReVelle will join Peter Brown of the University
of Western Ontario; Alan Hildebrand from the National Research Council in
Ottawa, Ontario; a researcher from University of New Mexico's Institute of
Meteoritics; and Mark Boslough of Sandia National Laboratory.
Los Alamos National Laboratory is operated by the University of California
for the U.S. Department of Energy.
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An Affirmative Action/Equal Opportunity Employer
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Copyright Notice
For Scientific and Technical Information Only
Copyright © 1996, 1997 the Regents of the University of California.
For All Information
Unless otherwise indicated, this information has been authored by an
employee or employees of the University of California, operator of the Los
Alamos National Laboratory under Contract No. W-7405-ENG-36 with the U.S.
Department of Energy. The U.S. Government has rights to use, reproduce, and
distribute this information. The public may copy and use this information
without charge, provided that this Notice and any statement of authorship
are reproduced on all copies. Neither the Government nor the University
makes any warranty, express or implied, or assumes any liability or
responsibility for the use of this information.
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