The case for a giant plume of water vapor wafting from Jupiter's potentially life-supporting moon Europa just got a lot stronger. NASA's Hubble Space Telescope has spotted tantalizing signs of such a plume multiple times over the past half decade, but those measurements were near the limits of the powerful instrument's sensitivity. Now, researchers report in a new study that NASA's Galileo Jupiter probe, which orbited the planet from 1995 to 2003, also detected a likely Europa plume, during a close flyby of the icy moon in 1997. The newly analyzed Galileo data provides "compelling independent evidence that there seems...