[meteorite-list] NASA Team Cites New Evidence That Meteorites From Mars Contain Ancient Fossils

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 5 May 2010 15:53:16 -0700 (PDT)
Message-ID: <201005052253.o45MrGlW010027_at_zagami.jpl.nasa.gov>

http://www.washingtonpost.com/wp-dyn/content/article/2010/04/30/AR2010043002000.html

NASA team cites new evidence that meteorites from Mars contain ancient fossils
By Marc Kaufman
Washington Post
May 4, 2010

LEAGUE CITY, TEX. -- NASA's Mars Meteorite Research Team reopened a
14-year-old controversy on extraterrestrial life last week, reaffirming
and offering support for its widely challenged assertion that a
4-billion-year-old meteorite that landed thousands of years ago on
Antarctica shows evidence of microscopic life on Mars.

In addition to presenting research that they said disproved some of
their critics, the scientists reported that additional Martian
meteorites appear to house distinct and identifiable microbial fossils
that point even more strongly to the existence of life.

"We feel more confident than ever that Mars probably once was, and maybe
still is, home to life," team leader David McKay said at a
NASA-sponsored conference on astrobiology.

The researchers' presentations were not met with any of the excited
frenzy that greeted the original 1996 announcement about the meteorite
-- which led to a televised statement by President Bill Clinton in which
he announced a "space summit," the formation of a commission to examine
its implications and the birth of a NASA-funded astrobiology program.

Fourteen years of relentless criticism have turned many scientists
against the McKay results, and the Mars meteorite "discovery" has
remained an unresolved and somewhat awkward issue. This has continued
even though the team's central finding -- that Mars once had living
creatures -- has gained broad acceptance among the biologists, chemists,
geologists, astronomers and other scientists who make up the
astrobiology community.

Speaking at a four-day conference near NASA's Johnson Space Center,
McKay's team didn't claim it had definitive proof that the meteorites
they are studying -- which can be identified as Martian because the
gases inside them match the Martian atmosphere -- contain the remains of
living organisms. Rather, the researchers described their re-energized
confidence as emerging from a process of nitty-gritty science, based on
inference, simulated testing and a kind of interplanetary forensics.

McKay cited years of work by team members Kathie Thomas-Keprta and Simon
Clemett that he said rebuts a central critique of the meteorite's
significance. He also pointed to the presence of what appear to be
fossilized microbes in other Martian meteorites, as well as the steady
flow of discoveries by others pointing to a Mars that at one time could
have supported life -- wet, warmer and enveloped in a potentially
protective atmosphere and a magnetic field.

Rebutting the critics

The Thomas-Keprta work, published late last year in the journal
Geochemica, centers on the origin of iron-based crystals called
magnetites in the original Mars meteorite, called ALH84001. Magnetites
on Earth are sometimes created by bacteria that respond to the planet's
magnetic field; the McKay team argued that some of the Martian
magnetites were of this biologically created type.

Critics had said that the magnetites could have just as easily existed
without bacteria or biology -- that they sometimes form as a result of
the shock and searing heat that could come, for instance, from an
asteroid strike. But in the recent paper, Thomas-Keprta, an expert in
the use of electron beam technology to look inside rocks, reported that
the purity of the magnetites made that explanation impossible.

Reflecting both the contentiousness and drama of the debate,
Thomas-Keprta finished her talk by referring to a recent article in a
science journal that said the astrobiology community had "mostly
abandoned" the biological explanations for the makeup of ALH84001. Her
retort: "As Mark Twain put it, 'Reports of our death have been greatly
exaggerated.' "

McKay complained that not enough attention had been paid to work such as
Thomas-Keprta's.

"All the criticisms of our original paper got widely distributed, but
when we did the work to prove the critics were wrong, it hardly made a
ripple," he said at a conference interview. "We're now in a position to
say we've knocked down all the criticisms -- and our biological
explanation is the one left standing."

Mary Voytek, director of NASA's astrobiology program, praised McKay and
his team for their continued research into Mars meteorites, saying they
have been crucial to the field.

She said, however, that the astrobiology community as a whole remained
unconvinced of their findings, in part because "the bar is so high." She
also said it was still not proved that any possible microfossils on the
meteorites had come from Mars, rather than forming as contaminants after
the meteorites landed on Earth. In addition, all the Martian meteorites
consist of hard igneous rock; the more fragile sedimentary rock, which
is most likely to contain sign of life, falls apart before reaching Earth.

Strong feelings

Because the stakes involved with any announcement of possible or likely
extraterrestrial life are so high -- both for science and for the
societal and religious implications of such a discovery -- the issue
brings out very strong feelings. At the conference, a leading cautionary
voice in astrobiology proposed that a special protocol be established to
oversee release of any journal articles making dramatic extraterrestrial
claims.

Andrew Steele, of the Carnegie Institution for Science in Washington and
once a member of the McKay team, compared the absence of astrobiology
review with the formal procedures set up by scientists involved with the
search for extraterrestrial life, or SETI.

He said that SETI leaders understood the societal sensitivity of their
work and that it was time for researchers in astrobiology "grow up and
do the same."

Astrobiology is the relatively new field of science that both searches
for and tries to understand life beyond Earth, as well as how life began
on Earth. The biennial conference attracted more than 700
microbiologists, chemists, geologists, astronomers, geochemists and
other researchers drawn into what might be science's most
interdisciplinary field.

Even as scientists debate McKay's assertions, the field has become
increasingly optimistic about the possibility of finding remains (or
perhaps even samples) of microbial life on Mars. Scores of papers
presented during the conference supported the view that the now dry and
frigid planet once was warm, wet and seemingly quite habitable.

For instance, NASA planetary scientist Carol Stoker said that NASA's
Phoenix lander -- which touched down near the Martian north polar region
in 2008 -- found conditions that were harsh but even today suitable for
life. Stoker, who was a co-investigator for several instruments on the
Phoenix, said that data sent back met predetermined criteria that would
indicate that the area could have supported Martian life even in recent
times.

Steven Squyres, another top scientist with extensive knowledge of Mars,
said that he, too, is convinced that Mars once had conditions that could
support life.

The principal investigator for the two NASA rovers, Spirit and
Opportunity, that have traveled Mars for the past six years, Squyres
said that Mars once had water at or near the surface, now has many
minerals that can be formed only in the presence of water and even had
springs that once produced hot water and steam.

"These are all things that lead to local habitable niches," he said.
"When you have the evidence right there in front of you for
habitability, it makes a convincing case that you better go out and see
if anyone lived out there."

In a plenary session, in which Squyres solicited the group's views on
how the field should move forward, McKay stood up to say that examining
possible Martian microfossils should be a much higher priority. He said
that the "biomorphs" now being found could answer some of the basic
questions about life on Mars and that it could be done at a much lower
cost than the multibillion-dollar alternative plan -- sending a rover to
Mars to pick up some rock samples and bringing them back to Earth.

"These meteorites are samples from Mars," he said, "and need to be
treated as the valuable resource they are."
Received on Wed 05 May 2010 06:53:16 PM PDT