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Science Frontiers ONLINE No. 110: Mar-Apr 1997 |
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Martian Life: Act Ii
The final issue of New Scientist for 1996 carried an article entitled "Death Knell for Martian Life." Was all that media hype for naught? What will NASA do now? Wait! Another putative Martian rock may save the day.
Picked up in Antarctica in 1974, meteorite EETA 79001 weighs 7.9 kilograms and is superficially unimpressive. Inside, though, researchers I.P. Wright and C.T. Pillinger found a surprising quantity of organic compounds -- actually 1.5 parts per thousand by mass. This fraction is so large that terrestrial contamination seems remote. Furthermore, the organic component contains 4% more carbon-12 (relative to carbon-13) than the adjacent carbonate minerals. This is strong evidence that the organics had a biological origin. Similar tests on the media-hyped Martian meteorite ALH 84001 yielded the same carbon ratios. Pillinger remarked:
"These results offer the strongest support yet for the hypothesis that life once existed on the planet."
So far so good, but EETA 79001 conveys two additional facts -- both very tantalizing: (1) This meteorite was blasted off the Martian surface only about 500,000 years ago; and (2) It probably came from a different hemisphere than ALH 84001. From all this, a somewhat shaky conclusion: Life on Mars existed not only recently (and perhaps is still present) but was (or is) widespread on the planet!
(Anonymous; "Life on Mars: Part Two," Sky and Telescope, 93:12, January 1997. Anonymous; "More Evidence for Martian Life," Astronomy, 25:26, February 1997.)