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Martian soil may contain life
24/08/2007 11:04 - (SA)
London - 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% 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.
"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 fuelled 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.
Life, but not as we know it
While most scientists think our next-door neighbour in the
solar system is lifeless, the discovery of microbes on Earth
that can exist in environments previously thought too hostile
has fuelled 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.
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