NASA on Friday issued an unusual denial of a report that its researchers saw strong evidence for life's existence on present-day Mars, based in part on atmospheric methane readings. Other scientists involved in Mars research said the jury was still out on the meaning of Martian methane, but they agreed that the preliminary findings were well worth a follow-up.
Earlier this week, sources told the weekly Space News that Carol Stoker and Larry Lemke, astrobiologists at NASA's Ames Research Center, had submitted a paper to the journal Nature outlining the evidence for biological activity on the Red Planet.
But in Friday's statement, NASA said such reports were "incorrect":
"NASA does not have any observational data from any current Mars missions that supports this claim," the statement read. "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."
Space News reports appear on MSNBC.com by virtue of a content partnership with Space.com, which like Space News is a brand franchise of New York-based Imaginova Corp. Space.com said it stood by the original report, published online Wednesday, and posted a follow-up Friday.
The follow-up included additional details about the private meeting on Sunday during which Stoker and Lemke were said to have discussed their research. It said some of the attendees now had "conflicting recollections" about the status of the research paper. The report also noted that Stoker was scheduled to present a paper next month about her group's research in Spain's Rio Tinto region, which offers some parallels to Martian chemistry.
Efforts to reach Stoker and Lemke on Friday were unsuccessful, but David Morse, Ames' public affairs director, told MSNBC.com that "there never was a paper submitted to Nature." He said the focus of Stoker's research had to do with drilling experiments at Rio Tinto.
"They're learning about the process by which you might make a determination of life on Mars," Morse said. That may be the subject of research yet to be submitted for publication, he added.
Speaking on condition of anonymity, sources told MSNBC.com that Stoker and Lemke distributed an e-mail to space science colleagues on Wednesday, taking issue with the original report. The e-mail message, forwarded to MSNBC.com, says the account was based on inaccurate hearsay.
The message says that the researchers discussed Mars research while attending "a private party of space exploration enthusiasts," but were speaking merely as individual scientists and not on NASA's behalf.
Hot topic for planetary scientists
Methane as a possible biomarker for Mars life is indeed a hot topic at scientific meetings, said Tobias Owen, a specialist in planetary atmospheres at the University of Hawaii. Owen is involved in studies of methane on Mars as well as on Titan, Saturn's smog-shrouded moon.
He referred to last year's findings from Europe's Mars Express orbiter, indicating slight but unexpected levels of methane in the Martian atmosphere. This week, New Scientist magazine reported that an Italian researcher, Vittorio Formisano, believed that the Mars Express readings for methane and formaldehyde were indicative of life — although his own colleagues are reportedly far more cautious about such claims.
Owen said the detected methane levels are probably too small to yield definite conclusions about whether or not it was created through biological or geological processes, he said.
However, future missions such as the Mars Science Laboratory, slated for launch in 2009, could conduct an on-the-ground atmospheric analysis of carbon isotopes contained in the methane molecules, he said.
"If it were life, and if that life is like the methane-generating bacteria on Earth, then you would expect that the carbon 12-carbon 13 isotope ratio would be elevated," he said. "The only way you can do that is biological."
At the same time, he cautioned that methane-generating life on Mars could well be nothing like the analogs on Earth. So if the carbon readings don't match Earth's, "that doesn't mean that it's not caused by life," Owen said.
NBC News space analyst James Oberg contributed to this report.