Study: Martian soil may contain life

LONDON, England (Reuters) -- The soil on Mars may contain microbial life, according to a new interpretation of data first collected more than 30 years ago.

The search for life on Mars appeared to hit a dead end in 1976 when Viking landers touched down on the red planet and failed to detect biological activity.

But Joop Houtkooper of the University of Giessen, Germany, said on Friday the spacecraft may in fact have found signs of a weird life form based on hydrogen peroxide on the subfreezing, arid Martian surface.

His analysis of one of the experiments carried out by the Viking spacecraft suggests that 0.1 percent of the Martian soil could be of biological origin.

That is roughly comparable to biomass levels found in some Antarctic permafrost, home to a range of hardy bacteria and lichen.

"It is interesting because one part per thousand is not a small amount," Houtkooper said in a telephone interview.

"We will have to find confirmatory evidence and see what kind of microbes these are and whether they are related to terrestrial microbes. It is a possibility that life has been transported from Earth to Mars or vice versa a long time ago."

Speculation about such interplanetary seeding was fueled a decade ago when researchers said an ancient meteorite found in Antarctica contained evidence of fossil life on Mars. Doubt has since been cast on that finding.

Houtkooper is presenting his research to the European Planetary Science Congress in Potsdam, Germany.

While most scientists think our next-door neighbor in the solar system is lifeless, the discovery of microbes on Earth that can exist in environments previously thought too hostile has fueled debate over extraterrestrial life.

Houtkooper believes Mars could be home to just such "extremophiles" -- in this case, microbes whose cells are filled with a mixture of hydrogen peroxide and water, providing them with natural anti-freeze.

They would be quite capable of surviving a harsh Martian climate where temperatures rarely rise above freezing and can fall to minus 150 degrees Celsius.

Houtkooper believes their presence would account for unexplained rises in oxygen and carbon dioxide when NASA's Viking landers incubated Martian soil. He bases his calculation of the biomass of Martian soil on the assumption that these gases were produced during the breakdown of organic material.

Scientists hope to gather further evidence on whether or not Mars ever supported life when NASA's next-generation robotic spacecraft, the Phoenix Mars Lander, reaches the planet in May 2008 and probes the soil near its northern pole.