The Meteors Are Coming -- NASA Astrobiology To Shower Attention On Leonids

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-space.arc.nasa.gov/~leonid/. During the mission, video animation and images will be available at: http://leonid.arc.nasa.gov.