Europa's Ice Shell Measured at Eighteen Miles Thick as Scientists Debate Ocean Life Potential

Juno Delivers First Direct Ice Shell Measurement

NASA has announced a landmark finding from the Juno spacecraft: Jupiter's moon Europa has an ice shell averaging approximately eighteen miles thick. The measurement, published in Nature Astronomy, settles a long-running scientific debate about whether the shell is thin or thick.

The data came from Juno's Microwave Radiometer during a close flyby in twenty twenty-two. Scientists note that if Europa's ice contains dissolved salts, as some models suggest, the shell could be somewhat thinner. Conversely, if a warmer convective layer exists beneath the rigid outer ice, the total thickness could be even greater.

Competing Views on Life Beneath the Ice

The thick shell complicates the search for life, as nutrients and oxygen would need to travel a considerable distance from the surface to reach the ocean below. However, two studies published this month offer starkly different perspectives on Europa's habitability.

Researchers at Washington State University propose that dense, salt-rich ice on Europa's surface could slowly sink through the shell in a process called crustal delamination. This mechanism, borrowed from Earth geology, could deliver life-supporting chemicals to the hidden ocean over time.

A Quiet Seafloor Raises Questions

A contrasting study from Washington University in Saint Louis paints a less optimistic picture. Researchers modelling Europa's internal structure and the gravitational forces from Jupiter found little evidence for tectonic activity or hydrothermal vents on the seafloor. These features are considered important for supporting life in Earth's deep oceans.

Europa Clipper to Provide Answers

Both sets of findings highlight the importance of NASA's Europa Clipper mission, which launched in October twenty twenty-four and successfully completed a Mars gravity assist in March twenty twenty-five. The spacecraft is scheduled to arrive at Jupiter in twenty thirty, where it will conduct nearly fifty close flybys of Europa to investigate the ice shell, ocean, and potential for habitability.