By Kathleen Wong
In a universe with billions upon billions of planets, narrowing the search for extraterrestrial life is no mean feat. One approach seeks analogs of otherworldly conditions here on Earth, and characterizes the mineralogy, geochemistry and biology of these areas.
To NASA scientists, a former gold mine turned natural reserve at the intersection of Napa, Yolo, and Lake Counties looked likely to have just such an analog environment. Soils at McLaughlin Natural Reserve include serpentinite, a rock formed when a mineral in Earth’s upper mantle called olivine contacts water. Olivine is also ubiquitous on Mars, asteroids, and the rocky cores of planetary moons.
Serpentinization—the reaction that forms serpentinite when water interacts with olivine—rips hydrogen from water molecules and generates caustic fluids similar to household ammonia or bleach. Microbes adapted to this alkaline environment consume the hydrogen as their primary energy source, producing methane as a byproduct.
NASA scientists have drilled wells on the reserve to determine whether active serpentinization is occurring underground. The water they extracted was not only highly alkaline, but contained methane. They soon found microbes in the wells capable of metabolizing hydrogen and carbon dioxide. Recent probes on Mars have discovered water, methane, and organic compounds on the surface—the same conditions found at McLaughlin.
McLaughlin now provides the first in-situ observation platform for microbial communities in a subsurface serpentinizing environment. Scientists plan to elucidate how energy and carbon flow in this ecosystem, and obtain insights into the potential for extraterrestrial serpentinizing environments to support life. In future studies, the scientists will attempt to resolve the origin of methane in McLaughlin’s wells and trace the fate of hydrogen and carbon monoxide in these systems.
Managed by UC Davis, McLaughlin is one of the 49 reserves in the UC Natural Reserve System, the largest university-administered reserve system in the world.
More information: More about this project from the NASA Astrobiological Institute.
Kathleen Wong is a publications coordinator for the UC Natural Reserve System.