In search of meteor showers, an airborne research mission indicates that the chemical precursors to life found in comet dust may well have survived a plunge into early Earth's atmosphere.
Text based on a NASA/Ames Press Release
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."
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.