Life on Mars: Take two.
Using electron microscopy, researchers from NASA's Johnson Space Center in Houston and their colleagues identified minute spherical and rod-shaped features suggestive of fossils in the Martian meteorites Nakhla, about 1.3 billion years old, and Shergotty, about 180 million years old.
"Because we are finding evidence for fossilized organisms in meteorites with such young ages, it is conceivable that there could still be life somewhere on Mars at the present time," says study collaborator Kathie Thomas-Keptra of Lockheed Martin Corp. in Houston. Her team announced the findings in March at the annual Lunar and Planetary Science Conference in Houston.
Thomas-Keptra says the possible fossils have much in common with mineralized bacteria found in terrestrial rock known as Columbia River basalt. The spherical and rod-shaped features in the Martian samples are rare but occur in patches, a pattern "highly suggestive of biological activity," she notes. "Inorganic chemical precipitation, for example, would not likely occur in sporadic, random, colonylike patches."
John P. Bradley of MVA in Norcross, Ga., and the Georgia Institute of Technology in Atlanta says it's best to keep an open mind. However, he says that there's no compelling evidence that these features must be fossils. "The absolutely key prerequisite is to look inside these objects to see if you can see cellular structure," he says. "In the absence of that, [the scientists are] going to spin their wheels."
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|Title Annotation:||minute spherical and rod-shaped features identified on Mars|
|Date:||May 1, 1999|
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