Scientists are busily working on a framework for assessing exoplanets for the presence of life, but what about extraterrestrial life a little closer to home? There are a few moons in the solar system that could conceivably support life. After analyzing data collected in the final days of the Cassini mission, researchers say there is new evidence that Saturn’s moon Enceladus could support life.
The Cassini probe spent years orbiting Saturn and sending back reams of data to NASA for analysis. When the probe ran low on fuel, NASA decided to retire it in a way befitting its station. The “Grand Finale” saw Cassini dive into the planet’s atmosphere last fall. NASA did this in order to prevent the spacecraft from ever impacting one of Saturn’s moons, where it could contaminate a potential biosphere. We don’t know if there are any biospheres on Saturn’s moons, but it’s looking more likely today.
On its way to crashing into Saturn, Cassini flew through a plume of water blasted out from Enceladus. While it’s frigid in the outer solar system, tidal forces from Saturn’s intense gravity heat the interior as it orbits. As a result, there’s a liquid ocean under the surface. The extent and nature of this body of water is unknown, but geysers of water escaping through cracks in the surface reveal its presence.
Cassini detected complex organic molecules in the water of Enceladus, which could mean something is alive down there. Carbon-based chemistry doesn’t mean life on Enceladus is a sure thing, but it is a necessary precursor to the development of life. Previously, we had only confirmed that simple organic molecules like methane existed on Enceladus. The new discovery makes this the only location in the solar system other than Earth with all the basic requirements for life.
Of course, any life on Enceladus is locked away under its icy shell. Anything alive there would probably be similar to Earth organisms that cluster around hydrothermal vents on the ocean floor. Rather than collecting energy from sunlight, the Enceladus biosphere could get its energy from hydrogen, which Cassini has also detected on Enceladus.
Searching for solid evidence of living organisms on Enceladus will prove quite difficult. We don’t yet know what it would take to break through the surface into the watery depths, or whether that’s even possible. Still, Enceladus might be the best place to go looking for E.T.
Enceladus, Not Europa, Could Be the Best Place to Search for Extraterrestrial Life
Saturn's moon Enceladus has many of the same properties as Europa, and our greater knowledge of this moon could make it easier to detect life.