University of Hawaii University Relations (808) 956-8856 Telephone Media & Publications (808) 956-3441 Facsimile Honolulu, HI 96822 email@example.com E-Mail Contact: Ed Scott, Hawaii Institute of Geophysics and Planetology, 808-956-3955, Donnė Florence, PIO, 808-956-7522 For Immediate Release: August 14, 1998
One year ago, UH scientists Ed Scott, Sasha Krot and Akira Yamaguchi announced that the carbonates they studied in a sample of the Martian meteorite ALH84001 appeared to have formed in an impact at temperatures that were too high for organisms. Scientists at NASA and Stanford University, who argue for life in the Martian meteorite, countered that the disk-shaped grains they studied were diffferent from the grains examined by Scott and his colleagues.
Since then Scott and his colleagues have used electron and optical microscopes to study carbonates of all shapes and sizes in over a dozen samples of the Martian meteorite. They wanted to know how the rock had been deformed, fractured and heated by impact and how and when the carbonates had formed in the fractured rock.
The UH scientists found that the disk-shaped carbonates, like the grains they had studied earlier, appeared to be completely enclosed in the rock. Detailed studies of the carbonate shapes and compositions showed that they had grown in fractures as the rock had been squeezed and the fractures closed. The shapes and heterogeneous distribution of carbonates in the sealed fractures indicated that the carbonates grew rapidly from a hot fluid that was present in the rock when the fractures were opened and then closed by impact. The carbonate shapes and distribution could not be explained by growth from a fluid that was slowly percolating through fractures at low temperatures, as the NASA scientists inferred.
"Our study should help to resolve the controversy over the formation temperature of the carbonates," says Scott. "We conclude that the existing carbonates formed at high temperatures by impact heating of carbonates that had formed earlier at low temperatures in pores between crystals."
Two additional teams of scientists using electron microscopes report on their studies of the famous Martian meteorite in the current issue of Meteoritics and Planetary Science. They also conclude for entirely different reasons that NASA scientist David McKay and his colleagues were mistaken in claiming to have discovered evidence of Martian microorganisms.
"The evidence against life in the Martian meteorite has been steadily accumulating during the past year," says Scott. "At the same time, more scientists than ever before are studying Martian meteorites for clues to past conditions on Mars." Were there once oceans and rivers on Mars? What was the composition of the early atmosphere on Mars? Could life have evolved on Mars? Not since astronauts landed on the Moon has there been so much excitement about rocks from space.
"Mars mania" is apparent in the current issue of Meteoritics and Planetary Science, which contains 19 papers on Martian meteorites by 50 scientists working in six countries. Even though McKay's group is probably wrong about life in the Martian meteorite, their work has started an explosion of interest in the possibility of life on the red planet and elsewhere in the solar system, says Ed Scott.
Scott and Sasha Krot both work in the Hawaii Institute of Geophysics and Planetology, which is part of the School of Ocean and Earth Science and Technology at the University of Hawaii at Manoa. Akira Yamaguchi, formerly with HIGP, now works at the National Institute for Research in Inorganic Materials in Tsukuba, Japan. Their work at UH was partly supported by a grant from NASA to HIGP Director Klaus Keil, and a grant from the National Science Foundation.
Life on Mars? Read "Planetary Sciences Research Discoveries" on line at
Last year's news release about the work of Scott, Yamaguchi and Krot is on
the web at http://www.hawaii.edu/ur/News_Releases/NR_May/Mars.html
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