A puzzling moon. A dark journey. A hunt for extra-terrestrial life. NASA knows it has a sexy mission on its hands with the Europa Clipper: "People care about it, people want to know about this mysterious world that might harbor life," NASA scientist Robert Pappalardo tells Space.com. But NASA is still designing the spacecraft that will launch as early as 2023, pass Jupiter's icy Europa moon about 40 times, and gather data about its composition, geology, and unseen ocean. Any possible life there exists underwater, where microorganisms might be feeding on seafloor geologic activity; the solar system's harmful radiation can't pose a risk because it's blocked by the ice. And the ocean is huge—about twenty times deeper than Earth's, per Boise State Public Radio.
NASA will also measure the shell's thickness and see if gaps let seawater plumes burst into space (like on the Saturn ice moon, Enceladus). And because radiation prohibits the spacecraft from orbiting Europa, it will move around the Jupiter system and catch a glimpse of other moons. "Io happens to be right there," says NASA scientist Christina Richey. "Who doesn’t want to look at the planetary body that looks like a pox-ridden abyss?" For now, NASA is still analyzing the design, finishing the budget, choosing the trajectory, and deciding which launch vehicle will carry Europa Clipper on a three-year or five-to-six-year journey. With any luck, it will send back revealing images: "Europa we don't really get—there are these really key mysteries we’re trying to understand," says Pappalardo. (Astronomers discovered a "super-Earth" six light years away.)