NASA just found evidence of a plume spewing from Europa — buried inside the data of an old spacecraft
(The Verge) Scientists have uncovered the biggest evidence yet that water may be spewing from the surface of Jupiter’s icy moon Europa — a revelation that was buried deep within the archives of a long-dead NASA spacecraft. In 1997 the Jupiter probe, Galileo, flew near a geyser when it passed close by Europa, collecting data that went overlooked at the time. But now, the rendezvous has been unearthed 20 years later, and it provides scientists with their first up-close measurement of one of Europa’s water plumes.
Up until now, scientists have strongly suspected that water is pouring out from Europa, but the matter hasn’t been fully settled. The only evidence we have for these geysers comes from NASA’s Hubble Space Telescope, which captured images of water escaping from the distant moon in 2012 and 2016. But Hubble’s pictures were taken from afar and are pretty fuzzy; they haven’t been considered definitive proof. This discovery from Galileo, detailed today in Nature Astronomy, “is the strongest evidence we have so far in terms of seeing signatures of a plume at Europa,” Xianzhe Jia, a planetary scientist at the University of Michigan and lead author of the study, tells The Verge.
Europa’s plumes are thought to stem from a global saltwater ocean lurking underneath the moon’s crust. It’s a feature that’s made this icy world a prime candidate in the search for life elsewhere in our Solar System. Water is vital for life here on Earth, so many have wondered if organisms might be able to survive in Europa’s waters as well. And plumes offer a great opportunity for studying what’s inside this ocean. Scientists don’t need to send a spacecraft to land on the moon and drill into its icy surface; they can simply send a vehicle to fly by the moon and sample its plumes — a much easier type of mission to pull off.
That’s exactly the kind of mission NASA plans to do in the early 2020s. The space agency has been working on a robotic spacecraft called Europa Clipper, which will fly by Europa’s surface upward of 40 times to get a taste of these plumes. Before today’s findings, it was still somewhat unclear if Europa Clipper would actually see any plumes while it was out there.
Jupiter’s moon Europa, as seen from NASA’s Galileo spacecraft