In its quest to find extant life in the Solar System, NASA has focused its gaze on the Jovian moon Europa, home to what is likely the largest ocean known to humans. Over the next decade, the space agency is slated to launch not one, but two multi-billion dollar missions to the ice-encrusted world in hopes of finding signs of life.
Europa certainly has its champions in the scientific community, which conducts surveys every decade to establish top priorities. The exploration of this moon ranks atop the list of most desirable missions alongside returning some rocky material from Mars for study on Earth. But there is another world even deeper out in the Solar System that some scientists think may provide an even juicer target, Saturn’s moon Enceladus. This is a tiny world, measuring barely 500km across, with a surface gravity just one percent of that on Earth. But Enceladus also has a subsurface ocean.
“I have a bias, and I don’t deny that,” says Carolyn Porco, one of the foremost explorers of the Solar System and someone who played a key imaging role on the Voyagers, Cassini, and other iconic NASA spacecraft. “But it’s not so much an emotional attachment with objects that we study, it’s a point of view based on the evidence. We simply know more about Enceladus.”