RESEARCH SUPPORTS EVIDENCE OF MARTIAN MICROBES.

Byline: Mark Carreau Houston Chronicle

Researchers from the California Institute of Technology offered new support Thursday for the claim by NASA scientists that a meteorite holds fossil evidence of primitive Martian life. They also suggested that microorganisms from the Red Planet could have survived a long journey to Earth.

The findings, published Thursday in the journal Science, are based on new studies of the meteorite's magnetic properties.

While they do not directly address the issue of whether the tiny sausage-shaped objects discovered by NASA researchers inside the meteorite are fossil remains, the findings show for the first time a thermal history of the rock that is conducive to biological activity.

Researchers at the National Aeronautics and Space Administration's Johnson Space Center in Houston, led by geologist David McKay, made their controversial findings public last August. They acknowledged that a lengthy debate would rage before the global science community reached a consensus. The findings are scheduled to be discussed next week in Houston at the 28th Lunar and Planetary Science Conference.

Skeptics have argued that the tiny globules of carbon-based material in which the suspected micro-fossils were found by McKay's team could only have been formed by high-temperature processes hostile to life - perhaps as hot as 1,300 degrees Fahrenheit.

``If that were true, then none of these things could have evidence of life,'' Caltech geobiologist Joseph Kirschvink said of the orange-tinged globules tucked within the recesses of the meteorite's fractured surface. The origin of the globules, organic or artificial, has become a crucial part of the debate.

Kirschvink is the principal author of a report that examines the meteorite's magnetic properties.

``What we are able to show from the magnetic studies is that these things couldn't have been heated even to the boiling point of water,'' Kirschvink said in a telephone interview. ``We should have been able to detect even a brief heating event over (212 degrees), and we didn't.

``Bacteria are associated with carbonate formation, and there are bacteria-generated globs of carbonate that look very similar to those on the fracture surfaces,'' Kirschvink concluded.

His team - consisting of McGill University mineralogist Hojatollah Vali and Altair Maine, a 16-year-old graduate student from Caltech - contend their thermal findings support the possibility that microbial life trapped within the meteorite could have survived the long trip from Mars to Earth.

That conclusion supports the intriguing possibility that a primitive form of life could migrate from one planet to another.

In August, McKay and his research team presented this account of their discovery:

Some 4.5 billion years ago, the rock that later became known as meteorite ALH 84001 originated as volcanic lava under the surface of Mars as the planet formed.

Five hundred million to a billion years later, water laden with carbon dioxide from the Martian atmosphere flowed over the rock, percolating through its fractures. That process exposed the rock to the carbonate globs containing the bacteria-like life forms.

Though now dry, barren, cold and supporting only a thin atmosphere, Martian geology suggests the planet was once warmer and home to flowing water and possibly large seas.

Sixteen million years ago, Mars was struck by a mile-wide comet or asteroid, objects massive enough to eject debris, including ALH 84001, with enough velocity to escape the planet's gravitational pull. The date is based on an assessment of the rock's exposure to cosmic rays.

Thirteen thousand years ago, the rock fell to Earth, landing in the Alan Hills region of the Antarctic. U.S. scientists searching for meteorites found it in 1984.

Later archived at the Johnson Space Center, the 4.2-pound meteorite did not pique the interest of researchers for years. In 1993, however, they began to unravel its origins.

Samples of trapped gases found in the rock matched the characteristics of air samples analyzed on the Martian surface by NASA's Viking landers in 1976. Only a dozen such meteorites recovered on Earth show such a match.

For their studies, Kirschvink's team analyzed a piece of the meteorite the size of a grain of sand. It was cut in half, so its structure could be studied with an ultra-high-resolution superconducting magnetometer.

The results revealed that the sample from which tiny carbonate globules were found had two magnetic directions, one on each side of the small fractures. The finding was critical. Had the meteorite been heated to a high temperature and cooled, as skeptics argued, the differing fields would have realigned in a uniform direction.