NSF PR 98-74 - November 6, 1998
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Research Aircraft Fly Below Once-in-a-Century Leonid
Meteor Storm
Two research aircraft carrying new scientific observing
instruments and high-definition TV cameras will seize
a once-in-a-lifetime opportunity to observe the Leonids
meteor shower on November 17, 1998. Only once a century
does Earth's orbit cross the dense part of the tail
of Comet Temple-Tuttle, which produces the storm.
An L-188C Electra, owned by the National Science Foundation
(NSF) and operated by the National Center for Atmospheric
Research (NCAR) in Boulder, Colo. will be joined by
an Air Force KC-135 in the night skies over Okinawa,
Japan, during the meteor storm.
"The NSF Electra is an ideal platform to participate
in the Leonids meteor experiment," says Cliff Jacobs,
program manager in NSF's division of atmospheric sciences,
which funds NCAR. "Its ability to accommodate multiple
state-of-the-art, upward-looking instruments will
provide an exceptional opportunity to study these
meteors."
The meteor storm will occur when Earth enters the dense
debris behind Temple-Tuttle on November 17, 1998,
and again on November 18, 1999. Although the comet
returns every 33 years, its orbit crosses Earth's
only once every hundred years. This century's crossing
offers scientists a close look at the trails of unusually
fresh and large (millimeter- to centimeter-size) meteors
entering the earth's atmosphere at the fastest possible
speeds -- 72 kilometers per second (160,000 miles
per hour). Best observations will be from East Asia
(China and Japan). Next year, Europe and North Africa
will offer the best viewing. From the ground, the
source of the storm appears in the constellation Leo.
The National Aeronautics and Space Administration is
heading the experiment, which is the first mission
in NASA's Astrobiology Program, created to study the
origin and prevalence of life in the universe. The
Leonid Multi-Instrument Aircraft Campaign is also
supported by NSF, the U.S. Air Force, and NHK Japanese
television.
The two aircraft are needed to take the observing instruments
into clear skies above the weather-laden lower atmosphere.
The Air Force's FISTA (Flying Infrared Signatures
Technology Aircraft) will circle the NSF/NCAR Electra
in a racetrack pattern between 30,000 and 40,000 feet
while the Electra flies back and forth (north-south)
about 10,000 feet lower within the loop. At these
altitudes (7 to 10 kilometers, or roughly 4 to 6 miles)
both planes will be safe from the meteors above, which
will burn up at 100 to 120 kilometers (60 to 75 miles)
above the ground.
A major scientific goal of the mission is to determine
how a meteor's mass compares to its brightness. To
date, scientists can only guess how much material
enters the atmosphere during a meteor shower. The
Electra will carry a dual-beam lidar (laser-based
radar) built this year to detect iron vaporized from
the meteors in the upper atmosphere. Says NCAR project
manager Bruce Morley, "We know very little about iron
in the atmosphere and even less about the iron contribution
from meteors. Observing just one meteor accurately
from the sky would make a big difference to our understanding."
Editors: High-resolution color photos
of the Electra are available via the Internet using
anonymous ftp: Log on to ftp.ucar.edu, using the userid:
anonymous password: [your e-mail address] directory:
/communications [include the slash] filenames: elecnight1.tif,
elecnight2.tif, elecnight3.tif, elecnight4.tif, and
electra.tif
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