Leonid Meteors Yield Rich Astrobiology Research Results

A team of NASA researchers and their collaborators report their findings from last year’s Leonid meteor storm in a special issue of the journal "Earth, Moon and Planets."

The scientists – all members of the NASA and U.S. Air Force-sponsored Leonid Multi-Instrument Aircraft Campaign – discussed their results in a series of astrobiology-related papers in the peer-reviewed journal. While their findings covered a range of areas, the key results reported have implications for the existence and survival of life’s precursors in comet materials that reach Earth.

"Last year’s Leonid meteor storm yielded rich research results for NASA astrobiologists," said Dr. Peter Jenniskens, a NASA astronomer based at Ames Research Center and principal investigator for the airborne research mission. "Findings to date indicate that the chemical precursors to life — found in comet dust — may well have survived a plunge into early Earth’s atmosphere."

Scores of meteors near the bowl of the Little Dipper, in a 10 to 12 minuteexposure by A. Scott Murrell during the 1966 Leonid storm. He used a 50-mm f/1.9lens and Tri-X film in a camera tracking the stars at New Mexico State University Observatory.
Credit: Sky and Telescope, November 1995

Jenniskens and his international cadre of researchers think that much of the organic matter in comet dust somehow survived the rapid heating of Earth’s atmospheric entry. "Organic molecules in the meteoroid didn’t seem to burn up in the atmosphere," he explained. They may have cooled rapidly before breaking apart, he concluded.

Another manner in which organic matter can somehow survive the fiery plunge into Earth’s atmosphere was discovered by a team from the Aerospace Corporation, Los Angeles, who detected the fingerprint of complex organic matter, identical to space-borne cometary dust, in the path of a bright Leonid fireball. This "fingerprint" is still under investigation to ensure that trace-air compounds are not contributing to the detection.

Another finding with potentially important implications for astrobiology is that meteors are not as hot as researchers had previously believed. "We discovered that most of the visible light of meteors comes from a warm wake just behind the meteor, not from the hot meteoroid’s head," said Jenniskens. This warm wake has just the right temperature for the creation of life’s chemical precursors, he said.

Utah State University researchers found that, during the meteors’ demise in the atmosphere, their rapid spinning caused small fragments to be ejected in all directions, quite far from the meteoroid’s head. This is an important finding for astrobiology, because it means that meteors may be able to chemically alter large amounts of atmosphere.

Related Web Pages

Interactive observing tool called the "Leonid MAC flux estimator" is available for the general public.
Dark Sky Image Predictor (270 kB graphic): Find a local site to observe the Leonids meteors
Sites to Watch:
The LEONID MAC live updates site at NASA Ames Research Center
Near Live Leonid Watching System at NASA HQ (George Varros)
Leonids 1999 (International Meteor Organisation)
Leonids live for forward meteor scatter
Leonids live from Yatsugatake Observatory, Japan
Japanese site that provided live updates during 1999 shower
Japanese site with special attention to highschool participation
ScienceNet (UK Leonid Watch)
Asteroids, Comets and Meteors site