January 28, 2026 — Data from NASA’s Juno mission has provided new insights into the thickness and subsurface structure of the icy shell encasing a subsurface liquid ocean within Jupiter’s moon Europa. Using the spacecraft’s Microwave Radiometer (MWR), mission scientists determined that the shell averages about 18 miles (29 kilometers) thick in the region observed during Juno’s 2022 flyby of Europa.

The thick shell suggested by the MWR data implies a longer route that oxygen and nutrients would have to travel to connect Europa’s surface with its subsurface ocean. Understanding this process may be relevant to future studies into Europa’s habitability.

"The thickness of Europa’s icy shell and the existence of cracks or pores within the ice shell are two crucial pieces of the puzzle for understanding Europa’s potential habitability,” said Scott Bolton, principal investigator of Juno from Southwest Research Institute. “They provide critical new information relevant to the further study of Europa by NASA’s Europa Clipper and the European Space Agency’s Juice (Jupiter Icy Moons Explorer) — both on their way to the Jovian system.” 

The new constraints on the ice thickness in the near-surface icy crust were published on Dec. 17, 2025, in the journal Nature Astronomy. Previous models have suggested the ice shell could be less than half a mile to as many as tens of miles thick.

Slightly smaller than Earth’s moon, Europa is one of the solar system’s highest-priority science targets for investigating habitability. Evidence suggests that the ingredients for life may exist in a vast saltwater ocean believed to exist beneath its ice shell. Juno’s determination of the ice shell thickness and the subsurface characteristics provides fundamental new constraints for understanding the moon’s structure, internal processes and potential habitability.