NASA team cites new evidence that meteorites from Mars contain ancient fossils

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."