Hydrogen
peroxide can bleach hair, propel rockets, and wipe out microbes. And that's
why a University of Michigan professor of atmospheric and space science
believes that we shouldn't expect to meet a Martian anytime soon.
Mars is thought to have been formed with the same ingredients that, on
Earth, created molecules that led to plant and animal life. Those molecules
haven't yet been detected on the Martian surface, and they probably
won't be, according to Sushil Atreya, a professor in the department
of atmospheric, oceanic, and space sciences at the Ann Arbor campus and
director of the university's Planetary Science Laboratory.
Atreya attributes the lack of life on Mars to fallout from extensive dust
storms on the planet. The storms can be dense and can cover wide areas.
A particularly large storm, for instance, erupted more than a year ago,
at the end of October 2005, when Mars and Earth were closer to each other
than they had been in years. The storm was reportedly visible to observers
using large backyard telescopes.
Atreya was part of a team that included researchers at the University
of Michigan; the University of California, Berkeley; Duke University;
the University of Alaska; the SETI
Institute; the Southwest Research Institute; the University
of Washington, and the NASA Goddard Space Flight Center. The research
was funded by NASA's Mars Fundamental Research Program and NASA
Goddard internal institutional funds.
"I had been studying the chemistry of Mars for more than a decade,"
Atreya told us, "but couldn't find a solution to a big puzzle:
What happened to all the organic material on the surface of Mars? Until
one day, when a colleague, Professor Nilton Renno, asked an unrelated
question: 'Do you think the electric fields in dust devils on Mars
could trigger new chemistry?' As I dug deep into the possible effect,
I found, much to my surprise, that this is where the answer to the lack
of detection of surface organics must lie."
According to Atreya, research suggests that the dust storms on Mars produce
enough hydrogen peroxide to make the planet's surface off-limits
for any kind of life. The hydrogen peroxide, which may condense and fall
like rain, would wipe out any organic molecules, he said.
"As a consequence, any nascent life—microorganisms, for example—would
find it hard to get a foothold on the surface of Mars," Atreya said. He
is the lead author of a paper, "Oxidant Enhancement in Martian Dust Devils
and Storms: Implications for Life and Habitability," that discusses the
research in an issue earlier this year of the journal Astrobiology.
According to Atreya, hydrogen peroxide, H2O2, is produced when electric
fields generated by the dust storms cause carbon dioxide and water molecules
to split. He said his team has calculated that the quantity produced would
be large enough to cause the hydrogen peroxide to condense. Essentially,
hydrogen peroxide would rain from the sky and destroy life forms where
it fell, Atreya said.
But his team hasn't ruled out the existence of life below the surface
of Mars.
"Of all the planets in the solar system, Mars resembles the Earth
most," Atreya said. "And outside of the Earth, it has the
best chance of being habitable now or in the past, when the planet may
have been warmer and wetter."
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