Posted: Mon, Feb 26, 2001, 9:51 PM ET (0251 GMT)
Scientists have found what they claim to be "compelling evidence" that magnetite crystals in the Martian meteorite ALH84001 have a biological origin. In a pair of papers to be published in the February 27th issue of the journal Proceedings of the National Academy of Sciences, scientists reported that both individual magnetite crystals, as well as long chains of the mineral, have features that could only exist had they been formed by primitive life forms. One group, led by Kathie Thomas-Keprta of NASA's Johnson Space Center, found that magnetite crystals found in the meteorite are identical to those created on Earth only by a strain of bacteria. Another group, led by Imre Friedmann of NASA's Ames Research Center, found that magnetite crystals formed chains somewhat like a string of pearls that, outside of an organism, would immediately collapse. These papers are the latest volleys in a 4 ½ year debate on evidence for ancient primitive Martian life in the meteorite, dating back to an August 1996 paper in the journal Science by a team that included Thomas-Keprta that used magnetite crystals as one of several lines of evidence that the meteorite was proof that life once existed on the Red Planet. These papers are unlikely to be the last words on the subject, either: Ralph Harvey, a scientist who has argued against a biogenic origin for the magnetite crystals in the past, told the Associated Press that it was "hasty" to rule out an inorganic method for creating the magnetite, noting that Thomas-Keprta's group focused on only a small fraction of the magnetite crystals in the meteorite.
