Aerospace Corporation Scientists on NASA Mission

Experience Meteor Storm Over East China Sea

EL SEGUNDO, Calif. (12/7/98) -- "It was lower than hoped, but not lower than expected," said Aerospace Corporation scientist Dr. David Lynch in a phone call from Okinawa, Japan, Nov. 17 describing the number of meteors that occurred over the Pacific in this year's Leonid meteor storm.

He had just completed an eight-hour flight aboard a highly specialized aircraft, scanning the skies with infrared spectrographs in search of the burning grains of dust and debris left by the comet Tempel-Tuttle.

Lynch and Drs. George Rossano, Ray Russell and Ted Tessensohn of The Aerospace Corporation were among an international team of scientists participating in a NASA mission to conduct detailed aircraft and ground measurements of the meteor storm. The mission involved two research aircraft carrying a broad array of scientific instruments.

The Aerospace Corporation scientists were aboard an Air Force Flying Infrared Signatures Technology Aircraft (FISTA) with 20 upward-looking portholes along the starboard side to facilitate observations. For the Leonids mission FISTA carried infrared cameras and spectrographs to dissect the meteor's light in search of the fingerprint of atoms and molecules.

The other craft, a modified L-188C Electra, carried a two-beam lidar, a type of radar with light pulses that measures the altitude of neutral atom debris in the meteor trails.

Flight from Okinawa

FISTA flew from Kadena Air Base in Okinawa over the East China Sea at an altitude of 39,000 feet, above the lower atmosphere's water vapor layer. The Electra flew at a lower altitude but nearby, acting as the mission "spotter" and recorder.

Lynch said the flight went well, even though the storm peaked 12 hours earlier than expected over the Atlantic, not the Pacific.

T

he Aerospace Corporation scientists spent a total of nine hours aboard the aircraft, seven in darkness monitoring instruments.

None of The Aerospace Corporation's team actually saw the meteors with their own eyes. The 20 portholes accommodated instrumentation only, leaving the scientists to read the results from their computer screens. Lynch was nonetheless enthusiastic about the experience. "There were a number of bright meteors, their trails lasting from a half to a full minute," he said.

International Team

Among the international participants was an expert from the Czech Republic who operated a spectrometer at one of the windows. A scientist from Mount Allison University, Canada, assembled and operated two state-of-the-art intensified cameras. Film crews from the Japanese Broadcasting Company and the British Broadcasting Company filmed the entire mission. Early reports indicated that all satellites on orbit escaped damage from the storm.

"We prepared for the worst and were pleased the shower did not directly threaten our space assets," said Maj. Gen. Gerald Perryman, commander of the 14th Air Force, in a statement issued from Schriever Air Force Base, Colo. The 14th Air Force comprises all Air Force space assets.

According to the Associated Press, officials in Moscow reported that the space station Mir was unaffected and that none of the 137 Russian military and civilian spacecraft were damaged.

Dr. Bill Ailor, director of the Center for Orbital and Reentry Debris Studies at Aerospace, said early reports indicated no "cataclysmic" damage occurred. But he said it is still too early to tell what lesser problems, such as intermittent electrical anomalies, might have occurred.

"These will take longer to be noticed," he said. "Reports will come in over the next several weeks, maybe months."

Conference in 1999

Ailor said detailed reports from satellite operators addressing anomalies or other issues related to the 1998 event will be presented at the Leonid Meteoroid Storm and Satellite Threat Conference to be held next May in Manhattan Beach, California.

The Aerospace Corporation scientists are processing the spectra collected aboard FISTA. The information will be used with data obtained earlier of comet Tempel-Tuttle, the parent body of the Leonid meteors.

The spectra will be analyzed to determine particle size and composition. The information will be used as input for models that simulate the effects of hypervelocity impacts, helping to characterize the threat of the meteoroids to orbiting spacecraft.

"Because the Leonids will be returning again in 1999 with the possibility of a bigger storm," said Lynch, "their threat remains real."