Jupiter’s moon, Europa, has long fascinated scientists. They believe it’s covered in a massive salty ocean, holding almost twice as much water as all of Earth’s oceans combined, making it one of the best places to look for extraterrestrial life in our solar system — but covered by a formidable icy shell. Now, NASA Jet Propulsion Lab scientists —drawing on data from the agency’s Juno mission, which performed a flyby of Europa in 2022 — have determined that this particularly heavenly body is seriously thick, measuring an average of 18 miles in the region observed by the spacecraft. It’s the first time we’ve been able to hone in on a specific measurement. Previous estimates have ranged from half a mile to tens of miles, highlighting how much there’s still to learn about Jupiter’s icy moon. The estimated thickness of the shell could also have major implications for future efforts to study Europa’s habitability. For one, nutrients and other building blocks like oxygen would have a very long way to travel. “If an inner, slightly warmer …