[meteorite-list] New Report Offers Evidence Of Primitive Life On Mars

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:37:34 2004
Message-ID: <200012140105.RAA13106_at_zagami.jpl.nasa.gov>

       John Ira Petty
       Johnson Space Center, TX
       (281) 483-5111

       December 13, 2000

       Release: J00-84

       NEW REPORT OFFERS EVIDENCE OF PRIMITIVE LIFE ON MARS

       A new scientific report offers compelling evidence that
       primitive life existed on Mars. Tiny magnetite crystals,
       identical to those used by aqueous bacteria on Earth as
       compasses to find food and energy, have been found in the
       Martian meteorite ALH84001. The report on the finding is in
       the December issue of Geochimica et Cosmochimica Acta.

       Written by a group of scientists led by Kathie Thomas-Keprta
       of Lockheed Martin at Johnson Space Center and funded by the
       NASA Astrobiology Institute, the report strongly supports the
       primitive life on Mars hypothesis of David McKay and coauthors
       in 1996.

       Coauthors of the new report on a four-year investigation are
       Dennis Bazylinski of Iowa State University, Joseph Kirschvink
       of the California Institute of Technology, Simon Clemett and
       Susan Wentworth of Lockheed Martin at the Johnson Space
       Center, David McKay and Everett Gibson of NASA's Johnson Space
       Center, H. Vali of McGill University in Montreal, and
       Christopher Romanek of the Savannah River Ecology Laboratory.

       Magnetite (Fe3O4) is produced inorganically on Earth. But the
       magnetite crystals produced by magnetotactic bacteria are
       different - they are chemically pure and defect-free. Their
       size and shape is distinct. Magnetotactic bacteria arrange
       these magnetite crystals in chains within their cells.

       Their characteristics make the magnetite crystals very
       efficient compasses, which are essential to the survival
       behavior of the bacteria. No one has found terrestrial
       inorganic magnetites, produced either naturally or in the
       laboratory, that mimic all the properties displayed by
       biogenic magnetites.

       "The process of evolution has driven magnetotactic
       bacteria to make perfect little bar magnets, which differ
       strikingly from anything found outside biology," said coauthor
       Kirschvink, a geobiologist. "In fact, an entire industry
       devoted to making small magnetic particles for magnetic tapes
       and computer disk drives has tried and failed for the past 50
       years to find a way to make similar particles. A good fossil
       is something that is difficult to make inorganically, and
       these magnetosomes are very good fossils."

       Scientists generally agree that ALH84001 is a member of the
       group of 16 meteorites found on Earth that originated on Mars.
       The potato-sized igneous rock is the oldest of them - about
       4.5 billion years. It lay in Antarctic ice for more than
       13,000 years. But the biogenic-type magnetite crystals are
       embedded in carbonates within ALH84001. Previous work by
       coauthor Chris Romanek has shown that these carbonates formed
       on Mars. Thus the magnetite crystals must also have formed on
       Mars.

       "These crystals are so tiny, ranging from 10 to 200 nm, that
       nearly a billion of them would fit on the head of a pin," said
       Thomas-Keprta. Using electron microscopy, team members
       examined the Martian magnetites still embedded in the
       carbonate and also removed about 600 crystals and examined the
       individual particles to determine their chemical composition
       and crystal geometry.

       The authors found that about a quarter of the Martian
       magnetites from ALH84001 are identical to magnetites produced
       on Earth by magnetotactic bacteria strain MV-1, which has been
       extensively studied by coauthor Bazylinski, a geobiologist and
       microbiologist who has developed many ways of culturing these
       difficult to grow microorganisms. "There is currently no known
       chemical means of producing these magnetite crystals with
       their unique morphologies," he said.

       Coauthor Clemett noted that "Mars is smaller than Earth and it
       developed faster. Consequently, bacteria able to produce tiny
       magnets could have evolved much earlier on Mars."

       When the team asserted in 1996 that Martian meteorite ALH84001
       showed signs of life existing on Mars, that planet was not
       known to have ever had a strong magnetic field. But since
       then, the Mars Global Surveyor has observed magnetized stripes
       in the crust of Mars that show a strong magnetic field existed
       early in the planet's history, about the same time as the
       carbonate containing the unique magnetites was formed.

       "ALH 84001 has been of great heuristic value in the field of
       astrobiology," said Baruch Blumberg, director of the NASA
       Astrobiology Institute. "Independent of its support or
       rejection, it has raised stimulating hypotheses that will help
       to focus our definition of how life, or variants of it, can be
       recognized."

       Vic Baker at the University of Arizona and Jim Head of Brown
       University have inferred abundant water on early Mars from the
       morphology of canyons prevalent on Mars. In a recent issue of
       Science, Michael Malin and Ken Edgett present evidence of
       widespread sediment layers on Mars that they interpret as
       produced by numerous lakes. Adrian Brearly of the University
       of New Mexico has found traces of ancient water, in the form
       of clay minerals, in ALH84001.

       Mars has long been understood to provide sources of light
       energy and chemical energy sufficient to support life. Early
       Mars, the authors note, may have had even more chemical energy
       produced by active volcanism and hydrothermal activity.

                                   -end-
Received on Wed 13 Dec 2000 08:05:03 PM PST