As the Cassini spacecraft executes its final daredevil maneuvers, scientists on both sides of the Atlantic are already thinking about the next mission to Saturn. But this time around, nobody’s talking about studying the gas giant itself. They’re talking about hunting for life in Saturn’s rings.
Two Saturnian moons—Titan, a world of frigid methane seas, and Enceladus, a cratered ball of ice wrapped around a liquid water ocean—are on the shortlist of places in our solar system where alien life might exist. And scientists are determined to find out if it does. That much was clear at last week’s American Geophysical Union conference, where American and European researchers presented proposals for two future spacecraft that would determine if Saturn’s strangest moons are habitable.
On the American side, there’s the Enceladus Life Finder (ELF), a proposed NASA New Frontiers-class spacecraft whose mission is in its name. ELF’s flight plan is simple: ten low-altitude (30 mile/50 km) passes over Enceladus’ south pole, where cracks in the moon’s icy crust spew frozen ocean water into space.
Diving through Enceladus’ south polar geysers, ELF would sample the moon’s ocean water like Cassini has already done, but with fancier instruments. Two state-of-the-art mass spectrometers would search for key indicators of habitability, including hydrogen gas (an energy source). The spacecraft would also hunt for life directly by profiling amino acids and carbon isotopes, which occur in specific patterns when microorganisms are present.
“The biggest hope for ELF is to fully characterize the habitability of Enceladus’ ocean,” Cassini project scientist and ELF co-proposer Linda Spilker said. “I would like to know if the Enceladus ocean can support life, and better yet, to find evidence for that life.”
Enceladus’ subsurface ocean is one of the most Earth-like environments we know of out there. But it’s also possible that a different form of biology—a far stranger one—could have sprung up in Titan’s methane seas. So, why only search for life-as-we-know-it when we can visit both moons on the same trip?