BOULDER--Two research aircraft carrying new scientific observinginstruments and high-definition TV cameras will seize a once-in-a-lifetime opportunity to observe in stereo the Leonids meteors, expectedto race at 160,000 miles per hour and bright as Venus into the Earth'supper atmosphere on November 17. An L-188C Electra, owned by theNational Science Foundation (NSF) and operated by the National Centerfor Atmospheric Research (NCAR) in Boulder, will depart from JeffersonCounty Airport on November 5, to be joined by an Air Force KC-135 in thenight skies over Okinawa, Japan, during the two-hour meteor storm. Onlyonce a century does the Earth's orbit cross the dense part of the tailof comet 55P/Temple-Tuttle, which produces the storm. NSF is NCAR'sprimary sponsor.
The National Aeronautics and Space Administration is heading theexperiment, which is the first mission in NASA's Astrobiology Program,created to study the origin and prevalence of life in the universe.Peter Jenniskens, of the Search for Extraterrestrial Intelligence (SETI)institute and NASA Ames Research Center, conceived of and organized theexperiment, called the Leonid Multi-Instrument Aircraft Campaign; it isalso supported by NSF, the U.S. Air Force, and NHK Japanese television.
"What the return of Halley's comet was to comet studies, the return of aLeonid storm will be to meteor astronomy," says Jenniskens. "The Leonidshowers' historic role cannot be overemphasized, but scientificobservations have been very few."
The two aircraft are needed to raise the observing instruments intoclear skies above the weather-laden lower atmosphere and to providestereoscopic observations. The Air Force's FISTA (Flying InfraredSignatures Technology Aircraft) will circle the NSF/NCAR Electra in aracetrack pattern between 30,000 and 40,000 feet while the Electra fliesback and forth (north-south) within the loop about 10,000 feet lower. Atthese altitudes (7 to 10 kilometers, or roughly 4 to 6 miles) bothplanes will be safe from the meteors above, which will burn up at 100-120 kilometers (60 to 75 miles) above the ground.
The meteor storm will occur when the Earth enters the dense debrisbehind Temple-Tuttle on November 17, 1998, and again on November 18,1999. Although the comet returns every 33 years, its orbit crosses theEarth's only once every hundred years. This century's crossing offersscientists a close look at the trails of unusually fresh and large(millimeter- to centimeter-size) material entering the earth'satmosphere at the fastest possible meteor speeds--72 kilometers persecond (160,000 miles per hour). Best observations will be from EastAsia (China and Japan). Next year, Europe and North Africa will offerthe best viewing. From the ground, the source of the storm appears to bethe constellation Leo.
A major scientific goal of the mission is to determine how a meteor'smass compares to its brightness. To date, scientists can only guess howmuch material enters the atmosphere during a meteor shower. To attackthe problem, the Electra will carry a dual-beam lidar (laser-basedradar) built this year to detect iron vaporized from the meteors in theupper atmosphere. Most meteors are rich in iron, which can be excited tofluorescence by the lidar's near-ultraviolet laser beams. The newinstrument was developed by scientists and engineers from the Universityof Illinois, NCAR, and the Aerospace Corporation.
Also on board will be an airglow imager; several high-resolutionvisible-wavelength imagers; and NHK's intensified, high-definition TVcameras. Researchers will compare meteor brightness on the TV cameraimage to the iron density and temperature measured by the dual lidar toarrive at a brightness-mass correspondence. This may enable them to oneday estimate the weight of a meteor shower from its brightness alone.
"The dual-beam lidar was built for the Electra, which provides anexcellent airborne platform for this kind of study, " says NCAR projectmanager Bruce Morley. "We know very little about iron in the atmosphereand even less about the iron contribution from meteors. Observing justone meteor accurately from the sky would make a big difference to ourunderstanding."
The Electra is a four-engine turboprop, modified and highly instrumentedfor atmospheric research. Participants flying on the Electra are fromthe University of Illinois at Urbana, the University of East Anglia(United Kingdom), NHK, and the SETI Institute.
NCAR is managed by the University Corporation for Atmospheric Research,a consortium of more than 60 universities offering Ph.D.s in atmosphericand related sciences.
Electra Flight Schedule for Leonids98(all are night flights for en-route research)
November 5 -- Depart Jefferson County Airport to NASA/Ames
November 6 -- Depart NASA/Ames to Maui
November 8 -- Depart Maui to Kwajalein (Johnson Island, fuel stop)
November 13 -- Depart Kwajalein to Guam
November 14 -- Depart Guam to Okinawa
Note to Editors: High-resolution color photos of the Electra are available viathe Internet using anonymous ftp: Log on to ftp.ucar.edu, using theuserid: anonymous; password: [your e-mail address]; directory:/communications [include the slash]; filenames are elecnight1.tif,elecnight2.tif, elecnight3.tif, elecnight4.tif, and electra.tif
Web Sites: For more information on Leonids98, see the following:http://www-space.arc.nasa.gov/~leonid/
During the mission, video animation and images will be available at: http://leonid.arc.nasa.gov
Find this news release on the World Wide Web athttp://www.ucar.edu/publications/newsreleases/1998/leonids.html
To receive UCAR and NCAR news releases by e-mail,telephone 303-497-8601 or e-mail [email protected]
The above story is based on materials provided by National Center For Atmospheric Research (NCAR). Note: Materials may be edited for content and length.
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