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Leonid MAC

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Mission Brief
Science Update
Media Brief


November  12, 1998

Donald Savage
Headquarters, Washington, DC
(Phone: 202/358-1727)

Kathleen Burton
Ames Research Center,
Moffett Field, CA
(Phone: 650/604-1731)
RELEASE: 98-202

On Nov. 17, 1998, NASA  scientists will conduct unprecedented, detailed aircraft and ground measurements  of the Leonid meteor storm.

The Leonid meteors  originate from a trail of dust and debris in the wake of the comet Tempel-Tuttle,  which orbits the Sun every 33 years. The Earth crosses this trail every  November, but every 33 years the debris trail is especially dense, sometimes  resulting in a meteor storm. The "shooting stars" streak through Earth's  upper atmosphere, sometimes at rates of up to thousands per hour. The storm's  peak lasts approximately one hour. This year, Earth is expected to pass  a region just behind the comet and outside of its orbit, a favorable set  of conditions for a larger-than-normal storm event. The best viewing of  this storm will be in eastern Asia and the western Pacific region.

NASA's mission consists  of two research aircraft that will carry a broad array of scientific instruments  to observe and explore the meteors. Operating simultaneously, the aircraft  will provide three-dimensional views, making high-resolution stereoscopic  images and spectrographic observations of meteor dynamics and chemistry.  A team of interdisciplinary scientists -- astronomers, atmospheric physicists  and meteor specialists -- will use state-of-the-art-sampling techniques  to provide a "window on the sky" over Japan during the storm.

"The central theme  of this mission is astrobiology,"  said Peter Jenniskens, mission principal investigator and astronomer at  the Search for Extraterrestrial Intelligence (SETI) Institute, Mountain  View, CA. "We are especially interested in learning  the composition of Tempel-Tuttle's debris, the molecules that are created  during the meteor's interaction with the Earth's atmosphere, and the composition  and chemistry of the atoms, molecules and particles detected in the meteor's  path. This may help us understand how extraterrestrial materials helped  create the conditions on Earth necessary for the origin of life."

The Leonid mission  is NASA's first operational astrobiology mission. Astrobiology is the study  of the origin, evolution and destiny of life in the universe. The mission  may provide important clues about what extraterrestrial materials were brought  to Earth by comets, and what part that may have played in the beginnings  of life on Earth, as well as clues on how biogenic compounds formed in stars  are eventually incorporated into planets.

A modified L-188C  Electra aircraft from the National Oceanic and Atmospheric Administration's  (NOAA) National Center for Atmospheric Research in Boulder, CO, and sponsored  by the National Science Foundation, will act as the mission "spotter" and  recorder. It will carry a two-beam Lidar, a type of radar with light pulses  that measures the altitude of neutral atom debris in the meteor trails.  Other instruments include airglow, visible wavelength imagers and high-definition  TV cameras.

Scientists aboard  the first aircraft are seeking to learn how a meteor's mass compares to  its brightness and to the mass of the resulting comet. Currently, they can  only guess how much material enters the atmosphere during a meteor bombardment.  Researchers will compare the meteor's image with information from the dual  Lidar, providing an indication of the chemical evolution of the meteor debris.

The second aircraft,  a U.S. Air Force-owned FISTA (Flying Infrared Signatures Technology Aircraft)  from Edwards Air Force Base, CA, will have 20 upward-looking portholes to  observe the meteors. It will carry imagers and infrared and visible-light  spectrometers to dissect the meteor's light in search of the fingerprint  of atoms and molecules.

The mission will fly  out of Kadena AFB in Okinawa, Japan, over the East China Sea. The FISTA  aircraft will fly as high as 39,000 feet to be above the lower atmosphere's  water vapor layer, while the Electra will maintain an altitude of about  22,000 feet, just above the clouds.

NASA's Ames Research  Center, Moffett Field, CA, is collaborating in this international effort  with the SETI Institute, the National Science Foundation and several other  science organizations. Aircraft and other support are being provided by  NOAA and the U.S. Air Force. Instruments are being contributed by the University  of Illinois at Urbana; the Aerospace Corporation; the Air Force Research  Laboratory; the Japanese Broadcasting Company (NHK); Kobe University, Japan;  the Ondrejov Observatory (Czech Republic); Mt. Allison University (Canada);  the SETI Institute; and the University of East Anglia, England. Additional  information on the Leonid meteor storm and the mission can be found on the  worldwide web at: http://www-  During the mission, video animation and images will be available at:

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