Jupiter's moon Europa hides a saltwater ocean that may contain more than twice the water of all Earth's oceans combined, yet a new measurement puts 29 kilometres of solid ice above it, a barrier taller than three Mount Everests stacked end to end

NASA’s Juno mission has provided a new measurement of the ice shell surrounding Jupiter’s moon Europa. Data collected by the spacecraft's microwave instrument indicates an average thickness of 29 kilometres. To put that scale into perspective, this layer of solid ice is thicker than three Mount Everests stacked on top of each other.

This measurement is based on a model rather than a direct physical scan. Researchers analyzed microwave emissions from the moon's surface during a 2022 flyby, accounting for heat and reflection patterns. While the estimate carries a margin of error of 10 kilometres, it moves current scientific understanding toward a thicker ice shell rather than a thin one. This result is significant because the thickness of this barrier dictates how much interaction occurs between the surface and the massive saltwater ocean hidden beneath.

That ocean is estimated to hold more than twice the volume of all water found on Earth. However, the 29-kilometre barrier suggests that transporting nutrients or oxygen from the radiation-exposed surface to the liquid interior is a difficult process. Recent studies into fluid dynamics indicate that water from the depths struggles to reach the surface, meaning the ice acts as a significant lid on the potential chemistry of the moon.

These findings provide a clear target for the upcoming Europa Clipper mission. The probe will conduct dozens of flybys to map the shell in greater detail and characterize its composition. While the ice poses a massive challenge for future exploration, it is also a fundamental part of the moon's environment. Understanding how this cold lid regulates heat and material movement is essential for evaluating whether the hidden sea could support biological activity.