I was waiting for someone mention the (funded and being built) JUICE mission: it's astonishing to me that the "if it ain't NASA, it ain't worth jack" attitude generally persists, and that hardly anyone in the media (let alone on
JUICE is under development by the European Space Agency for launch in 2022 (not 2020 anymore) and arrival at Jupiter in 2030. It will tour the Jupiter system, including multiple fly-bys of the giant icy moons Europa, Callisto, and Ganymede. It will end up in orbit around Ganymede, where it will conduct a more detailed survey.
All three moons are thought to harbour giant water oceans under (probably) very thick icy crusts (~100km), although there are debates about which may be the most likely to provide potentially habitable environments deep in these oceans: it may depend on central heat flux from the moon's contraction, flexure due to Jupiter's gravity, heat from radioactive decay, and whether there's a water:rock interface which could provide minerals.
Why Ganymede as the final moon to be orbited? Because Europa is closer to Jupiter and suffers a much higher radiation dose due to high energy particles trapped in Jupiter's magnetic field. Not necessarily an issue for life(?) buried deep in the oceans, but certainly an issue for the survivability of a spacecraft. Through the US's, umm, extensive military experience, NASA has access to higher-grade rad-hard electronics components than ESA, and so JUICE will only fly-by Europa a few times instead of bathing itself in that radiation.
But NASA is involved in JUICE too: several of the (many) instruments on JUICE have US Principal Investigators, funded by NASA. So, NASA is already going to Europa in a very real sense.