Ever since 2012, when astronomers using the Hubble Space Telescope first spied inconclusive hints of watery plumes emanating from the subsurface ocean of Jupiter’s large, icy moon Europa, space scientists have fiercely debated the claim. Previous estimates had suggested the moon’s crust might be tens if not hundreds of kilometers thick—too thick, that is, to allow direct exploration of its potentially life-friendly ocean anytime soon. A plume venting some of Europa’s ocean water into space where it could be sampled by an orbiting spacecraft would change the whole equation—it seemed, in short, too good to be true.
Now, however, a new analysis of 21-year-old data from NASA’s Galileo spacecraft, which orbited Jupiter from 1995 to 2003, has found strong independent evidence in favor of the plume.
This discovery all but confirms Europa should be considered a high-priority peer of another “ocean world” in the outer solar system, namely Saturn’s moon Enceladus, which also sports an even more dramatic plume. The finding also bolsters hypotheses that posit parts of Europa’s crust are far thinner and more fractured than previously believed—conditions that may allow life-sustaining energy as well as exploratory robots easier entry into the moon’s lightless abyss. Xianzhe Jia, a University of Michigan space scientist, and his colleagues published their findings on May 14 in Nature Astronomy.
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