WASHINGTON -- In
response to Space News' original
article "NASA Researchers Claim Evidence of Present Life on Mars" posted
Feb. 16 on SPACE.com and spacenews.com and picked up by other Web outlets, NASA
issued a statement calling the reports incorrect.
"NASA
does not have any observational data from any current Mars missions that
supports this claim. The work by the scientists mentioned in the reports cannot
be used to directly infer anything about life on Mars, but may help formulate
the strategy for how to search for martian
life. Their research concerns extreme environments on Earth as analogs of
possible environments on Mars. No research paper has been submitted by them to
any scientific journal asserting martian
life."
In
the original story, Space News
reported that a pair of NASA scientists, Carol Stoker and Larry Lemke, told a
group of space officials at a private meeting here Sunday that they had found
strong evidence that life may exist today on Mars.
NASA
spokeswoman Dolores Beasley said Feb. 18 that Stoker and Lemke were not
available for interviews. Stoker did not respond to messages left Feb. 15 on
her voice mail at Ames.
Space News interviewed a
half-dozen space officials who attended the Feb. 13 event at a private home in Northern Virginia. All requested that they not be
identified in print because the discussion was considered off the record.
All
attendees interviewed gave consistent accounts of Stoker and Lemke's
presentation to the group. Some attendees later had conflicting recollections
about what exactly Stoker said about her plans to publish her research. While
some said Stoker claimed she had submitted a paper to the journal Nature for publication in May, others
said Stoker only mentioned that she was preparing a paper for submission to Nature.
Nature said it
normally does not comment on whether a paper is under consideration for
publication or has even been submitted. Carl Ziemelis,
the physical sciences editor at Nature
in London, said
Feb. 18 that he was making an exception to that normal practice, telling Space News that the journal is not
preparing to publish Stoker and Lemke's research and that he first learned
about their work from news reports.
Stoker
and other researchers have long theorized that the Martian subsurface could
harbor biological organisms that have developed unusual strategies for existing
in extreme environments. That suspicion led Stoker and a team of U.S. and Spanish researchers in 2003 to
southwestern Spain
to search for subsurface life near the Rio Tinto river, so-called because of its reddish tint, the product of
iron being dissolved in its highly acidic water.
Stoker
told SPACE.com in 2003, weeks before
leading the expedition to southwestern Spain, that by studying the very acidic
Rio Tinto, she and other scientists hoped to
characterize the potential for a "chemical bioreactor" in the subsurface -- an
underground microbial ecosystem of sorts that might well control the chemistry
of the surface environment.
Making
such a discovery at Rio Tinto, Stoker said in 2003,
would mean uncovering a new, previously uncharacterized metabolic strategy for
living in the subsurface. "For that reason, the search for life in the Rio Tinto is a good analog for searching for life on Mars," she
said.
Stoker
told the private audience Feb. 13 that by comparing discoveries made at Rio Tinto with data that is being collected by ground-based
telescopes and orbiting spacecraft, including the European Space Agency's Mars
Express, there is a strong case to be made that life could exist below Mars'
surface.
The two scientists, according to sources who attended the Feb. 13 event, said Mars' fluctuating methane signatures and nearby surface concentrations of the sulfate jarosite, a mineral salt found on Earth in hot springs and other acidic bodies of water like Rio Tinto that have been found to harbor life despite their inhospitable environments, could be a sign of an active underground biosphere.
Methane
findings also have been the focus of some researchers examining data from the
European Space Agency's Mars Express satellite.
The
British magazine New Scientist
reported Feb. 16 that an Italian scientist, Vittorio Formissano of the Institute
of Physics and Interplanetary Science
in Rome, would be speaking at a Mars Express
conference in Noordwijk, the Netherlands the week of Feb. 21
about methane findings that he said can only be explained by the presence of
life. But as other scientists have pointed out, and the same New Scientist
article noted, methane in the concentrations that have been observed on Mars
could also be explained by non-biological processes such as volcanic activity.
Stoker, is slated to present a paper she
authored with Lemke and several others about the Rio Tinto
research and its implications for present life on Mars at the Lunar and
Planetary Institute's annual conference in League City, Texas,
March 14-18.
The
abstract of that paper, "Characterization of a Subsurface Biosphere in a
Massive Sulfide Deposits at Rio Tinto, Spain:
Implications for Extant Life on Mars," is posted on the Lunar and Planetary
Institute's Web site at www.lpi.usra.edu/meetings/lpsc2005/.
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