NASA team probes function, implications of 'rock-powered life'

Alexis Templeton plucks a small magnet from a polished green rock on her office desk. She eases her grip, and the magnet plops back onto the rock. This seemingly unremarkable attraction could indicate life once existed inside the rock, and illustrates a reason the NASA Astrobiology Institute wants to learn more.

Eons ago, the rock was not infused with the mineral magnetite. But it changed with a series of chemical reactions as the rock interacted with water. The reactions that would have produced magnetite would also have produced hydrogen gas, which Templeton calls “a great fuel source” for life.

“So did anything ever live in this rock in its past history? Currently, I don’t know, and part of what we’re looking for is how to demonstrate what are the signatures of life activity.”

Templeton, associate professor of geological sciences at the University of Colorado Boulder, leads a team of scientists who recently landed a $7 million, five-year grant from NASA to study “rock-powered life.”

The NASA award comes from the agency’s Astrobiology Institute, which funds collaborative, interdisciplinary research on origins, evolution, distribution and future of life in the universe.

The CU-Boulder team, one of seven the Astrobiology Institute just funded, will be known by its focus of study: Rock-powered Life.

“We study systems where rocks come into contact with water and because the two of them are not in chemical equilibrium with each other, reactions that release chemical energy potentially available to support life activity will ensue,” Templeton said.

Such rock-powered life relies on chemosynthesis, which does not need sunlight.

This type of geochemistry can occur on rocky planets such as Earth, as well as Mars or beneath a subsurface ocean on Jupiter’s moon Europa. And although the CU-Boulder led team is studying questions related to astrobiology, the research will take place on Earth—in California and Oman, where serpentinite rock like the one on Templeton’s desk is thought to be incubating life at low temperatures underground, rather than the high-temperature, hydrothermal areas on the ocean floor and land studied by previous researchers.

Templeton frames the questions this way: “If we drilled down three kilometers below our feet here, is there a living ecosystem in the rocks, and if so how is it getting its energy? … What are the series of reactions happening between the water and the rock, and then what are the reactions allowing the energy transfer to occur and be harnessed by the organisms themselves?”

When serpentinite rocks react with water underground, hydrogen and methane can be produced, and the water becomes hyperalkaline with a pH as high as 12. This is observed today in places such as California, Oman and along the Mid-Atlantic Ridge.

Thus, one focus of the team is on the chemistry in the rocks and water. Another is identifying the kind of chemosynthetic life that might exist there. “We intend to get whole organisms or DNA out of the rocks. We have to figure out who’s present in them, and how they function,” Templeton said.

That inquiry will also help answer key questions, such as these:

“What minerals get produced in the presence or absence of biology? Are there diagnostic markers of biological activity that we can learn to recognize in these rocks? Does that affect how we look for life on other planets?”

One third of Templeton’s Rock-Powered Life team is at CU-Boulder, and two thirds are at other institutions.

CU-Boulder investigators on the team include Templeton, Thomas McCollom at CU’s Laboratory for Atmospheric and Space Physics and Lisa Mayhew in geological sciences.

Other co-investigators on the CU-Boulder-led team include scientists from the Colorado School of Mines, Montana State University, Arizona State University, NASA Ames Research Center in Moffett Field, Calif., Michigan State University, the University of Rhode Island, the University of Utah and the Massachusetts Institute of Technology.

Besides the 12 investigators on the team, there are four core collaborators, including CU-Boulder Professor of Philosophy Carol Cleland and Associate Professor Brian Hynek of LASP, who also directs CU-Boulder’s Center for Astrobiology.

Cleland, known for her scholarly work on the definition of life and on possible shadow biospheres and “weird life,” will complement the work of the team’s natural scientists.

People generally think of life in terms of metabolism and genetic-based reproduction, Cleland said.

“My job on the team is partly to think about the nature of metabolism,” Cleland said. Additionally, she will examine data from the team, weighing the evidence about whether “these microbial communities (are) engaged in extra-cellular metabolic processes that are robust enough for the whole community to count as a living thing, rather than just the individual microbial cells within them.”

Cleland emphasizes the “interesting possibility” that the whole microbial community in the rock is alive as one entity. “Maybe the cells in the community represent evolved adaptations for performing certain metabolic and genetic processes more efficiently than the community as a whole. Is the community itself an individual living thing? … It requires a careful philosophical analysis as to what counts as metabolism.”

Maybe we are just fancy microbial communities that evolved from simpler microbial communities over time. Maybe the first living things were not composed of cells but consisted of complex acellular physico-chemical reaction networks.”

The potential implications extend well beyond rock-powered life. “Here’s the exciting thing,” Cleland said. “If you took this seriously and tried to ramp it up to understand large multi-cellular creatures like us, you might ask the following: Maybe we are just fancy microbial communities that evolved from simpler microbial communities over time. Maybe the first living things were not composed of cells but consisted of complex acellular physico-chemical reaction networks.”

The wide range of astrobiological expertise at CU-Boulder has established the university as a hub for such research and scholarship.

Undergraduate students don’t major in astrobiology here, “but there are opportunities to get connected intellectually with ideas relevant to astrobiology,” and graduate students can purposely engage in astrobiological research at CU, Templeton said.

In 1988, CU-Boulder was among the first group of 11 universities and federal labs to win a five-year grant from the NASA Astrobiology Institute. CU-Boulder won a second five-year grant in 2003.

Both times, the team’s leader was Bruce Jakosky, professor of geological sciences and principal investigator in the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, which reached the red planet in September.

After she joined the university in 2005, Jakosky invited Templeton to become an additional investigator with the Astrobiology Institute team at CU-Boulder.

“That was huge for me, because it immediately allowed me not only to join my department but to join this community beyond geology, and to recruit graduate students who had interdisciplinary interests that had connections to astrobiology.”

As many as half of the graduate students who joined Templeton’s research group came to CU-Boulder because of its work in astrobiology, she observed.

Templeton says CU was well-poised to pursue this NASA award. In recent years, the university has been highly supportive of the growth of “geobiology” as an area of excellence at CU.

This commitment to academic excellence in this area, combined with the university’s history in astrobiology, Templeton added, “played one critical role in my mind in CU being awarded this new opportunity to function as an active NASA Astrobiology Institute node for the next five years.”

For more information on NASA’s Astrobiology Institute, see http://astrobiology.nasa.gov.

Clint Talbott is director of communications and external relations manager for the College of Arts and Sciences and editor of the College of Arts and Sciences Magazine. Kenna Brunner, a feature writer for CU-Boulder’s University Communications, contributed to this report.