"We concluded in our paper that our measurements give no evidence for life," said Jim Papike, director of the Institute of Meteoritics at the University of New Mexico.
Papike and three colleagues began tests last year on the 4-1/2-pound, potato-sized meteorite, examining pyrite, or fool's gold, that had apparently crystallized in fractures in the rock.
The pyrite samples contain two sulfur isotopes, sulfur-32 and sulfur-34, whose ratio changes on Earth in the presence of biological activity.
"We wanted to know if these pyrites in Martian rocks would show this fingerprint of life that would be indicated by a specific type of ratio," Papike said. "When we looked at the ratio, there was no evidence that it was in a ratio for life forms."
In fact, the ratio points in the opposite direction from the one that indicates biological activity, he said.
Papike said his study does not necessarily mean NASA's conclusion is wrong. It's possible that primitive life on Mars did not have the same effect on sulfur that life on Earth does, he said.
The New Mexico scientists and the NASA team did not study the same slices of the meteorite. But Papike said the slices are identical geologically.
The study will be published this month in a scientific journal, Geochimica et Cosmochimica Acta, he said.
David McKay of NASA's Johnson Space Center reported Wednesday that golden-colored particles in the meteorite contained chemical and organic evidence that bacteria-sized organisms lived on Mars 3.6 billion years ago.
The NASA researchers also found tiny sausage-shaped particles that McKay interpreted as fossilized microbes because they resemble ancient bacteria found in Earth rocks.
"What remains to be done is to prove or disprove their claims," Papike said. "Therefore independent studies like ours must be done."
Copyright 1996 Associated Press. All rights reserved.
Original file name: .CNI - Researchers Doubt Mars
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