NEW REPORT OFFERS EVIDENCE OF PRIMITIVE LIFE ON MARS



December 13, 2000



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

<h4>Release: J00-84</h4> <h3>New Report Offers Evidence of Primitive 
Life on Mars</h3> 

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&rsquo;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 
&ndash; 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.



&ldquo;The process of evolution has driven magnetotactic bacteria to 
make perfect little bar magnets, which differ strikingly from 
anything found outside biology,&rdquo; said coauthor Kirschvink, a 
geobiologist. &ldquo;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.&rdquo;



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 &ndash; 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.



&ldquo;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,&rdquo; 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. &ldquo;There is currently no known chemical means of 
producing these magnetite crystals with their unique 
morphologies,&rdquo; he said.



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



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&rsquo;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,&rdquo; said Baruch Blumberg, director of the NASA 
Astrobiology Institute. &ldquo;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.

	
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