![]() The same, or a later, asteroid impact ejected the rock, now a meteorite, into space.Īnother NASA research group, led by Kathie Thomas-Keprta of NASA's Johnson Space Center, report in the same issue of PNAS that the magnetite crystals inside the meteorite are similar to those formed by 'modern' magnetotactic bacteria now living on Earth. This cataclysmic event on Mars' surface also may have killed the bacteria. The researchers say the magnetite chains probably were flushed into microscopic cracks inside the martian rock after it was shattered by an asteroid impact approximately 3.9 billion years ago. The chains were preserved in the meteorite long after the bacteria themselves decayed. The chains may have served as 'compasses' for the host magnetotactic bacteria, so named because they navigate with the help of the magnetic crystal chains inside their bodies. Magnetite is an iron oxide, similar to iron rust. Each magnetite crystal in the chain is a tiny magnet, approximately one-millionth of an inch in diameter. "The end result looks somewhat like a string of pearls," Friedmann noted. The chains were formed inside organic material whose structure held the crystals together. "Such a chain of magnets outside an organism would immediately collapse into a clump due to magnetic forces," he said. Imre Friedmann, an NRC senior research fellow at NASA's Ames Research Center in California's Silicon Valley and leader of the research team. "The chains we discovered are of biological origin," said Dr. 27 Proceedings of the National Academy of Sciences. The researchers found that the magnetite crystals embedded in the meteorite are arranged in long chains, which they say could have been formed only by once-living organisms. An international team of researchers has discovered compelling evidence that the magnetite crystals in the martian meteorite ALH84001 are of biological origin. ![]()
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