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Mars boulder field
A field of boulders and the Twin Peak mountains in this photo by Mars Pathfinder in 1997  

Researcher: Mars rock varnish hints of life

By Richard Stenger

(CNN) -- Many Mars rocks possess a chemical quality that suggests they harbor life, which could eke out an existence in a similar manner as microbes in the harshest, driest places on Earth, according to a new report.

Studying images taken by two Mars landers, a planetary researcher found striking similarities between rocks on the red planet and rocks in terrestrial deserts known to contain thin layers of primitive life.

The Mars rocks, photographed by NASA's Viking and Pathfinder probes in 1976 and 1997, appear to have shiny, dark coatings, much like terrestrial rocks covered with a kind of desert varnish linked to simple bacteria and fungi.

"I think if life exists on Mars today, it would be found in ... coatings like rock varnish," said report author Barry DiGregorio, who penned the 1997 book "Mars: the Living Planet." The Mars varnish resembles a manganese-rich variety produced only by terrestrial microorganisms on desert rocks, he said. The microbes remove metal particles from atmospheric dust and fog, oxidize them, and then build up layers and layers of varnish, using secretions as glue.

"All the right ingredients for this kind of life are already there on Mars," said DiGregorio.

Exploring Mars  
Space exploration  

Chemical analysis of martian meteorites has revealed that Mars boasts more manganese than Earth. Seasonal fogs on the red planet would moisten the rocks with enough water to supply resident organisms.

Moreover iron, which gives the planet its characteristic hue, would naturally cling to the varnish, protecting interior organisms from the harmful effects of intense ultraviolet radiation from the sun.

Whether the rock varnish is rich in manganese, and whether nature or past or present life created it, are questions that could be tackled by two U.S. rovers and one European lander that are scheduled to reach the red planet in 2003 and 2004. DiGregorio thinks one in particular is well suited for the quest.

"I think the British-built Beagle 2 lander has the right instrumentation and a very good chance to find out if this hypothesis is correct."

DiGregorio, who founded the International Committee Against Mars Sample Return, will present his new report later this month at an astrobiology conference in San Diego sponsored by the International Society for Optical Engineers.



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