URI geochemist seeks to unearth origins of life in universe

Study in northern California to examine ‘rock-powered life’

Todd McLeish, URI

KINGSTON, R.I. –University of Rhode Island geochemist Dawn Cardace and a team of scientists from a dozen other institutions are collaborating on a NASA-funded project to discover the origins and evolution of life in the universe.

The researchers will work at three field sites to study what they call “rock-powered life,” microbes that feed on the chemical energy released from the interaction of rocks and water deep beneath the Earth’s surface. Their findings will help to understand the processes that fueled early life on Earth and may provide insight into the habitability of Mars and other planetary bodies.

“We’re finding more and more evidence in the deep biosphere of microbes inhabiting pore spaces in rocks or in fluid pathways, where they aren’t dependent on carbon or photosynthesis from the surface,” said Cardace, URI assistant professor of geosciences. “It’s life of a different sort—surviving not on solar energy or photosynthetically-derived carbon but from the chemical energy inherent to our planet.”

Last month, NASA announced $50 million in grants to seven astrobiology research teams. Cardace’s team, led by the University of Colorado at Boulder, received $7 million, of which about $400,000 will come to URI.

“We’re studying part of the Earth’s biosphere that is essentially undocumented,” Cardace said. “We’re trying to define what goes on in the chemosynthetic realm, which may hold the keys to the origin of life and the stable conditions of the first cells on Earth.”

Fieldwork for the project includes close study of rock cores and formation waters from unusual rocks accessed at the Coast Range Ophiolite Microbial Observatory in northern California, where Cardace led a drilling project in 2011. She documented the presence of blocks of the Earth’s deep crust and uppermost mantle, which had been forced close to the surface by tectonics. Cardace will continue rock core characterization as part of the new research initiative and monitor water samples using her Microbe-Mineral Interactions Laboratory at URI. Primary analytical tools include petrographic and electron microscopy, x-ray diffraction, and infrared spectroscopy to examine mineral records of the interactions between water and rock.

“Our goal is to understand how microbes harvest the energy from these rock surfaces,” she said. “We’ll be able to observe changes in the mineral surfaces at a microscopic scale.”

Other members of her research team will conduct similar studies at sites in Oman and Yellowstone National Park, and a comparison of their findings will propel forward their understanding of how rocks host microbial communities, even in extreme environments.

According to Cardace, Mars has a deep crust and mantle that are mineralogically similar to those of Earth. Therefore, the deep biosphere habitats on Earth may have analogs on other planets, which may have sustained subsurface microbial.

“Other planetary bodies, like some moons of the gas giant planets, could also have similar rocks and similar liquids interacting to provide energy sources for life there, too,” she said. “One thing that most astrobiologists allow is that there may be more than one origin of life, even within our own solar system.”

While conducting her research, Cardace will teach several web-based courses to students at each of the participating institutions, provide graduate and undergraduate research opportunities in her lab, and establish an astrobiology minor at URI. “In this way, we bring the collaborative aspect of our research to our teaching mission, too,” she said.

Pictured above
URI Geosciences Professor Dawn Cardace (left) and graduate student Julie Scott examine rocks at the Coast Range Ophiolite Microbial Observatory. (Photo courtesy of Dawn Cardace.)