Thursday, December 10, 2009

Microbes in a Martian Meteorite.

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It has been 211/42 years since NASA researchers announced possible signs of fossil bacteria in a rock from Mars. Today the jury is still out - and the evidence has grown more cloudy.

Everyone who follows astronomy remembers the day. On August 7, 1996, NASA called a historic press conference at which a panel of nine scientists made a breathtaking announcement. Tentative evidence, they said, indicated that a meteorite from Mars contains fossil traces of ancient living organisms. With slides and graphs they described peculiar chemical residues, unusual crystal structures, and, most dramatically, electron-microscope images suggesting that tiny, bacteria-like microbes lived in cracks in the rock billions of years ago.

Suddenly the prospect of life on Mars - even if only microscopic life in the remote past - was resurrected from the grave to which the Space Age seemed to consign it a generation ago. David McKay and his coworkers at NASA's Johnson Space Center were careful to stress that they did not have proof. Each of their four lines of evidence, they said, could be accounted for without life processes. But bacterial action seemed like the simplest explanation for the whole combination. "The relationship of all these things in terms of location, found within a few hundred-thousandths of an inch of one another, is the most compelling evidence," said McKay.

The announcement dominated world news that day, prompted a statement of encouragement by President Clinton, and was widely rated the top science story of 1996. If true, it would imply that life arose from inorganic matter twice independently in one solar system (assuming that early life was not seeded from Mars to Earth or vice versa). This in turn would mean that life originates on planets easily - so the entire universe should be teeming with at least primitive living things. In the days following the announcement the public and the media embraced the claims, but most scientists were much more cautious if not deeply skeptical (S&T: October 1996, page 18, and July 1997, page 36). Further research, all agreed, was urgently needed to confirm or disprove the claim.

Now, two and a half years later, what is the status of the Martian microbes? Will history record them as appealing illusions, like Percival Lowell's canals on Mars a century ago? Or will they truly mark humankind's first step in finding alien life?

Source Citation
Treiman, Allan. "Microbes in a Martian Meteorite." Sky & Telescope Apr. 1999: 52. Academic OneFile. Web. 10 Dec. 2009. .

Gale Document Number:A54155019

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