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No Life In Mars Meteorite, UH Scientists Reaffirm

University of Hawaii
University Relations           (808) 956-8856 Telephone
Media & Publications           (808) 956-3441 Facsimile
Honolulu, HI 96822                 ur@hawaii.edu 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
 
No life in Martian meteorite, UH scientists reaffirm
 
University of Hawaii scientists have discovered more evidence against the
claims that a Martian meteorite contains signs of ancient life on Mars. Their
work, which is published today in Meteoritics and Planetary Science, shows
that all of the carbonate crystals in the rock formed during an impact and
could not have been deposited by living organisms.
 
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
http://www.soest.hawaii.edu/PSRdiscoveries
 
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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