Dust storms
raging across the surface of Mars may
wield toxic chemicals that could poison any forms of life as we know it on the
planet's surface, according to two NASA-sponsored studies.
Small dust
devils and planet-wide
storms - combined with static electricity - may lead to the formation of
hydrogen peroxide and other corrosive chemicals that fall to the Martian
surface as a sort of toxic snow, the reports stated.
"We are
trying to look at the features that make a planet habitable or uninhabitable,
whether for life that developed there or life that we bring there," said one
study's lead author Gregory Delory, a University of California, Berkeley
physicist, in a statement.
Delory and
his colleagues found that Martian dust storms, like their Earthly counterparts,
can generate electric
fields that rip apart water and carbon dioxide molecules in the planet's
thin atmosphere. Those molecules would then be free to form hydrogen peroxide
and other toxic oxidants that could scour the Martian surface of any organic
molecules crucial for the formation of life.
A second
study, led by University of Michigan researcher Sushil Atreya, found that the
levels of hydrogen peroxide that could coalesce from Martian dust storms would be high enough to condense into snow that could blanket the surface below.
"As a
consequence, any nascent life (microorganisms, for example) or even prebiotic
molecules, would find [it] hard to get a foothold on the surface of Mars, as
the organic material would have been scavenged by the surface oxidants," said Atreya,
a professor with the university's Department of Atmospheric, Oceanic and Space
Sciences, in a statement.
Both studies
- which drew on Earth dust storm observations, computer models and lab
experiments - appeared in a recent issue of the journal Astrobiology.
They were conducted for NASA's Goddard Space Flight Center and the agency's
Mars Fundamental Research Program.
Planetary
scientists have long known that Mars'
surface presents a hostile environment for life to take root, though
observations by NASA's hardy Spirit
and Opportunity rovers and other probes still exploring the red planet today
have found signs that water
once wet the surface long ago. Some spacecraft - including Europe's Mars
Express and NASA's recently arrived Mars
Reconnaissance Orbiter - are using radar to probe beneath
the planet's surface for caches of liquid or ice water, which scientists
believe is an essential
ingredient for the formation of life.
Meanwhile, the
studies led by Delory and Atreya may help answer one long-lasting riddle of
Mars exploration.
NASA's two
Viking landers found conflicting
results when they tested Martian soil for signs of life in the mid-1970s. The
landers added water and nutrients to Martian dirt to see if it contained any
microorganisms. One instrument watched the nutrients as something broke them
down, but another recorded no signs of organic matter in the Martian material.
The
presence of hydrogen peroxide or ozone in the Mars dirt could have fooled the
Viking instruments by producing reactions similar to that expected from
microorganisms, researchers said, adding that the substance could also break
down methane
seen in the Martian atmosphere.
"The
presence of peroxide may explain the quandary we have had with Mars, but there
is still a lot we don't understand about the chemistry of the atmosphere and
the soils of the planet," Delory said.
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