Scientists: Life on Mars Likely
Not so long ago it was unthinkable for respectable scientists to talk
about life on Mars. Such talk was best left to X-Files fans. But no
longer.
Evidence is building to suggest biological processes might be operating
on the red planet, and life on Mars, many scientists believe, is now
more a likelihood than merely a possibility.
"The life on Mars issue has recently undergone a paradigm shift," said
Ian Wright, an astrobiologist at the Planetary and Space Sciences
Research Institute at the Open University in Britain, "to the extent
now that one can talk about the possibility of present life on Mars
without risking scientific suicide."
Much of the excitement is due to the work of Vittorio Formisano, head
of research at Italy's Institute of Physics and Interplanetary Space.
In February, Formisano presented data at the Mars Express Science
Conference at Noordwijk in the Netherlands. If scientists had been
quietly excited before seeing Formisano's data, they were frenetic
afterward.
Formisano showed evidence of the presence of formaldehyde in the
atmosphere. Formaldehyde is a breakdown product of methane, which was
already known to be present in the Martian atmosphere, so in itself its
presence is not so surprising. But Formisano measured formaldehyde at
130 parts per billion.
To astrobiologists it was an incredible claim. It means huge amounts of
methane must be produced on Mars. (While methane lasts for hundreds of
years in the atmosphere, formaldehyde lasts for only 7.5 hours.) "It
requires that 2.5 million tons of methane are produced a year," said
Formisano.
"There are three possible scenarios to explain the quantities:
chemistry at the surface, caused by solar radiation; chemistry deep in
the planet, caused by geothermal or hydrothermal activity; or life," he
added.
And, with no known geological source of formaldehyde on Mars, it's
clear where Formisano's suspicions lie.
"I believe there is extremely high probability that microbial
subsurface life exists on Mars," he said, while acknowledging that
although he believes in Martian life, he can't yet prove it.
"What will certainly be needed in the future is a drill on a lander and
direct evidence of the existence of Archaea bacteria," Formisano said,
adding that he intends to publish his data in a forthcoming issue of
planetary science journal Icarus.
The European Space Agency certainly wants to send a rover to Mars, and
was urged to do so at an international space workshop at Aston
University in Birmingham, England, earlier this month. To get a lander
on Mars will almost certainly require the involvement, at some level,
of NASA.
But NASA has its own surface mission planned. Scheduled to arrive in
late 2010, the Mars Science Laboratory rover will use an array of
instruments to look for evidence of life.
"Europe and the U.S. are in a friendly competition to find life first,"
said Yuk Yung, professor of planetary science at the California
Institute of Technology, "which is healthy for science -- and funding."
The race to find proof of life started in earnest in 1996, after NASA
scientists published a paper claiming that the Martian meteorite
ALH84001 contained evidence of past biological activity. While that
claim remains controversial, it kick-started a change in mood about the
possibility of present life on Mars. Excitement grew in 2003 when
Michael Mumma, of NASA's Goddard Space Flight Center in Greenbelt,
Maryland, reported he had detected methane in the Martian atmosphere.
Then last year Vladimir Krasnopolsky, of the Catholic University of
America in Washington, D.C., made a similar claim about methane. Both
researchers had measured methane using ground-based telescopes.
But while the issue of life on Mars may have undergone a paradigm
shift, it is really only in Europe that scientists are openly excited.
In the United States, NASA is cagey.
According to Wright at the Open University, NASA is gun-shy about
sending up another life-finding Martian probe.
"NASA staff probably still remember Viking, which was a mission
designed specifically to look for life on Mars, but which found none --
and which subsequently killed off Martian exploration for a couple of
decades," he said. "ESA people don't have such baggage."
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