They took a class Johnson offered called Ocean Worlds, which focused on bodies like Europa that are thought to have oceans beneath icy shells. (sciencedaily.com)
Europa probably hosts a vast saltwater ocean buried under a thick icy shell. (sciencenews.org)
The goal is to keep Juno from disrupting any aliens — microbial or otherwise — that might live in hidden oceans of water below the icy shells of Jupiter's moons Europa and Ganymede. (businessinsider.com)