The ongoing search for extraterrestrial life has taken a rocky turn---and it's all for the best.
Yesterday at the Astrobiology Science Conference in Chicago, Illinois, NASA researchers discussed new projects and technologies that are expanding the search for life beyond Earth. And while that search has often focused on the need for water and heat, some astrobiologists are turning their attention to certain kinds of rock, which may be no less essential to fostering far-away lifeforms.
In the solar system, the icy moons of Jupiter and Saturn look like the best bets for finding living neighbors. Both Europa and its spirit twin Enceladus seem like good bets for hosting life because they have rocky cores, hidden beneath liquid water oceans and icy surfaces. Early next decade, NASA plans to launch a mission to fly by Europa a dozen times, collecting data that will guide future trips. Before launching into space, though, it's worth testing that idea in a laboratory scientists have ready access to: Earth.
Alexis Templeton, principal investigator for Rock-Powered Life (a project of the NASA Astrobiology Institute) and a member of the panel, is searching for microbes among rocks that were once part of Earth's mantle. These heavy, dark deposits (known as ultramafic rocks) are rich in iron and magnesium. They store energy in the form of charged particles which, if released, could theoretically support life. The way to couple this energy to living systems, Templeton believes, is water.
In Oman, Templeton's lab studies springs that bubble to the surface through ultramafic rocks. Water in the pools is highly alkaline, chemically transformed after sitting in contact with rocks for long periods of time. "It's a rare kind of water to find on the Earth," she says, but it may be common on moons like Europa and Enceladus. If that environment harbors life, it would broaden where people think life can exist at all.
But that raises the question of how to find that life, if it is there. That's what astrobiologist Britney Schmidt and her team are trying to figure out on the McMurdo Ice Shelf in Antarctica with their Sub-Ice Marine and PLanetary-analog Ecosytems project.
Their project uses five vehicles to explore the ice at the pole: a plane-mounted ice-penetrating radar, an ice-drill, and several remotely operated and autonomous underwater vehicles. "This is just the sort of thing we'd want to do on Europa one day," Schmidt says.
Similar ecosystems could exist beyond the solar system. Researchers like Victoria Meadows, principal investigator at the Virtual Planetary Laboratory, gather data to evaluate which exoplanets are promising candidates for harboring life. They're getting good at finding faraway planets with oceans, she says, along with evaluating a planet's atmosphere and how likely it is that it has been altered by life---though they can't yet detect ultramafic rocks.
But with missions like Kepler churning out an ever increasing number of exoplanets---1,852 confirmed to date, with 4,661 candidates---the neighborhood keeps getting bigger and bigger.
