NEW TRACES OF LIFE ON MARS
SAT, 14 Dec 1996
Source: Ndunlks@aol.com
From:Ndunlks@aol.com
By JOHN NOBLE WILFORD
NEW YORK -- Another meteorite from Mars has been found to contain evidence
for possible life on that planet, British scientists reported on Thursday.
American geologists, who in August first announced finding possibly
life-related chemical and mineral compounds in an older Mars rock, said that
the new research was "very exciting, and independent confirmation" of their
own startling and controversial results. The British discovery was certain to
encourage intensive testing of meteorites from Mars and increase scientific
interest in new spacecraft missions to the planet, the first of which is
scheduled for launching next Wednesday.
The fact that the latest evidence comes from a much younger meteorite,
scientists said, indicated that some kind of life could have existed on Mars
more recently than had been thought likely. Spacecraft observations of the
planet's landscape strongly suggest that Mars was once a warmer and wetter
planet and could have supported at least some forms of microbial life.
The British examined a meteorite, designated 79001, that crystallized 175
million years ago and was ejected from Mars, presumably by an asteroid
impact, only 600,000 years ago. The previous evidence came from a
potato-sized rock that crystallized about 3.6 billion years ago and was blown
away from Mars 16 million years ago. Both were found on the ice of
Antarctica.
"This is great," said Dr. Michael Meyer, a biologist who specializes in
extraterrestrial studies at the National Aeronautics and Space
Administration, in Washington. "It means we have more than one sample with
hints of life. And it means Mars could have been inhabited for quite a long
period and could even have some life today."
The new findings, reported in London at a meeting of the Royal Society,
were the result of research by Dr. Ian Wright and Dr. Colin Pillinger, of the
Open University, in Milton Keynes, England, and Dr. Monica Grady, of the Open
University and the Natural History Museum, in London. Their laboratory is
considered by scientists to be one of the best in the world for studying
carbon in extraterrestrial materials.
The British scientists could not be reached for interviews after the
meeting, but a description of their findings was included in the meeting
announcement. Their analysis revealed the presence of organic compounds in
the meteorite that could be associated with life. One line of evidence
suggested carbon compositions that are usually formed from microbially
produced methane.
Dr. Everett K. Gibson Jr., a geologist at the Johnson Space Center, in
Houston, was familiar with the research and provided details in a telephone
interview. He is a co-leader, with Dr. David S. McKay of the Johnson center,
of the team of NASA and university scientists that made the first discovery
of what they said were hydrocarbon compounds, minerals and possibly
microfossils associated with primitive microbial life on Mars.
"We're pleased that the British results support our data," Gibson said,
noting that they were based on a different type of analysis in a different
laboratory.
After the American report was published in August in the journal Science,
Gibson and his colleagues drew a skeptical response.
As Gibson described it, the British group heated samples of the meteorite
to several levels of high temperature, at each step examining gases emanating
from the rock. Any Earth contaminants near the surface would presumably have
escaped at the lower temperatures.
In this way, the scientists identified carbon compounds in the samples
with a composition that, Gibson said, "may be similar to that produced by
microbial activity." The signature for this was the discovered ratio of
carbon isotopes, atoms of the same element that have different numbers of
neutrons in their nuclei.
At least 12 meteoritic fragments, collected by geologists in Antarctica in
the 1980s, have been determined to come from Mars. The meteorite studied by
the British, 79001, is considered the "Rosetta stone" of the lot, because it
was the analysis of trapped gases within the rock that linked the objects to
Mars. The gases were almost identical in composition to atmospheric samples
gathered by the Viking spacecraft in 1976.
Definitive conclusions about the possibility of Martian life may have to
wait until spacecraft bring carefully selected samples back from the planet,
possibly in a decade or so. NASA is planning 10 flights of orbiting
spacecraft and robotic landers to explore Mars, beginning with the launching
next week of Mars Global Surveyor, a low-cost unmanned craft to study the
planet's climate and geology from orbit. Another craft, designed to land on
Mars, is to be launched on Dec. 2, aiming for an arrival at the planet next
July 4.
Other Places of Interest on the Web
Evidence of Primative Life From Mars
http://www.jsc.nasa.gov/pao/flash<
/A>
Life on Mars
http://www.fas.org/mars/
Mars Introduction
http://bang.lanl.gov/solarsy
s/mars.htm#
Center for Mars Exploration Homepage
http://cmex-www.arc.nasa.gov/
Mars facts and pictures from The Nine Planets Solar System Tour, maintained
by Students for the Exploration and Development of Space
http:/
/seds.lpl.arizona.edu/nineplanets/nineplanets/mars.html
Copyright 1996 The New York Times
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