Jupiter's moon Europa harbors a vast subsurface ocean beneath a thick ice shell, with water plumes occasionally erupting from its surface. Scientists are investigating whether these plumes originate from shallow reservoirs or the deep ocean below—a key question for astrobiology.
Like Mars and Saturn's moon Enceladus, Europa ranks among the top targets in the search for extraterrestrial life. Beneath 16 to 24 kilometers of ice lies a salty ocean potentially interacting with the rocky core, fostering complex chemical reactions that could support life. Europa's geological activity drives periodic water vapor releases, some soaring tens of kilometers high.
If life thrives in this hidden ocean, plumes could propel it to the surface. NASA's Europa Clipper mission, arriving in the 2030s, may sample these materials for analysis—though uncertainties remain.
A critical question for researchers: Do these plumes truly erupt from Europa's subsurface ocean? A collaborative team from NASA and universities including Arizona, Texas, and Stanford tackled this using data from the Galileo spacecraft, which orbited Jupiter in the late 1990s and early 2000s.
Focusing on the 29-kilometer-wide Manannán crater—formed by an impact tens of millions of years ago—the team modeled plume origins. The crater's scars indicate past eruptive activity.
The impact generated intense heat, melting ice and creating shallow brackish water pockets. These migrated laterally along thermal gradients toward warmer central areas, accumulating into a "lake."
Freezing compressed the water until it erupted as a plume over a kilometer high. "While these brine-driven plumes offer no direct ocean access, they highlight the ice shell's dynamic nature," says Joana Voigt, co-lead author.
This mechanism may not explain all plumes, as the study analyzes just one crater. Deeper ejections from the ocean to the surface remain possible, exciting astrobiologists.
The research also refines ocean salinity estimates from Galileo data (1995–1997): about one-fifth as salty as Earth's oceans, enhancing ice shell transparency to radar for future missions.
Findings appear in Geophysical Research Letters.
