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Air test suggests life possible on Mars

Could the red planet now be hosting life?
Could the red planet now be hosting life?  

By Richard Stenger

(CNN) -- A strange and hardy terrestrial microorganism can grow in atmospheric and soil conditions that in some ways resemble those on Mars, suggesting that life could thrive on the red planet, according to scientists.

The creatures, known as methanogens, survived in a thin atmosphere of hydrogen and carbon dioxide and in a special brew of volcanic ash altered to simulate the properties of martian soil, including its density, grain size and magnetic properties.

The results, in addition to the presence of vast stores of underground water on Mars, lend support to the theory that the planet once hosted or now hosts life, said Tim Kral, a researcher at the University of Arkansas in Fayetteville.

"With the recent successful missions to Mars -- Pathfinder, Global Surveyor, Odyssey -- and especially the discovery that there is probably a vast ocean of frozen water below the surface, there is a greater possibility that life may exist below the surface today," Kral said.

Kral and colleagues grew the test microbes in a pressure chamber with about half the density of the atmosphere on Earth. They documented the growth by studying how much methane was produced.

If life were to exist below Mars, it would need another energy source besides photosynthesis, the process plants use to make fuel from sunlight.

Methanogens, which thrive in some of the most inhospitable places such as peat bogs and sea floor vents, tap their energy not from the sun but from the oxidation of inorganic matter, in their case hydrogen and carbon dioxide.

"Assuming that hydrogen and some water are present under the surface, the basic requirements for methanogen growth are met on Mars," the scientists said in a statement.

Even if Mars does not have life, Kral speculates that if methanogens survive additional tests under more extreme conditions, they could be brought along by future colonizers to make the cold planet more comfortable for humans by releasing methane, a greenhouse gas.

But such "terraforming" might require hundreds or thousands of years before it could support more conventional forms of Earth life. There are other drawbacks as well.

"Of course, there are many potential ethical and environmental problems with this," Kral said.

Other scientists called the initial experiments intriguing, but stopped short of making plans to buy vacation property on the red planet.

Chris McKay of NASA's Ames Research Center in Moffett Field, California, noted that the Mars' atmospheric density is only a fraction of that in the test.

"But its an important step in the right direction and of course the particular microorganisms that they used are interesting since if there is subsurface life on Mars our best guess would be that it would be methanogens," the planetary scientist said.

"Certainly they are getting results that look interesting, in terms of atmospheric testing, but terraforming, that's a pretty big leap" said Steve Theison, an astronomer at the University of Maryland in College Park.

"Still, the discovery of extremophiles [species that live in harsh conditions] has opened up windows to possible life forms in extreme sites in other solar systems, like Europa and certainly Mars as well," added Theison, who specializes in astrobiology.

The Arkansas team plans to do more tests to simulate Mars conditions more closely, with increasingly lower atmospheric pressures, lower temperatures and high doses of radiation.

"In that sense, this is really provocatively interesting. I look forward to seeing what happens when they get this as close to Mars conditions as possible," Theison said.




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