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Planetary Radio • Feb 04, 2026

Europa’s quiet seafloor

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On This Episode

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Paul Byrne

Associate Professor of Earth, Environmental, and Planetary Sciences at Washington University in St. Louis

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Sarah Al-Ahmed

Planetary Radio Host and Producer for The Planetary Society

What if Europa’s seafloor isn’t alive with activity after all?

This week on Planetary Radio, host and producer Sarah Al-Ahmed explores new research that reframes how scientists think about one of the Solar System’s most intriguing ocean worlds.

Sarah is joined by Paul Byrne, associate professor of earth, environmental, and planetary sciences at Washington University in St. Louis. Paul is the lead author of a new study suggesting that the seafloor beneath Europa’s global ocean may be geologically quiet today, potentially lacking the hydrothermal activity often associated with habitable environments on Earth. Together, they discuss how scientists investigate places we can’t yet observe directly and why Europa remains a compelling world to explore regardless of what we find.

Then, Bruce Betts, chief scientist of The Planetary Society, joins us for What’s Up to explain why Saturn’s moon Enceladus shows strong evidence for active hydrothermal vents beneath its icy crust, offering a fascinating contrast between two ocean worlds.

Europa's high-resolution ridges and bands
Europa's high-resolution ridges and bands NASA's Juno spacecraft captured this image of Jupiter's moon Europa during a flyby on Sept. 29. It is possibly the highest-quality global view of Europa to date, showing sharp ridges and bands stretching across the icy moon's surface in approximate true color. This processed image was released in early October 2022.Image: NASA/JPL-Caltech/SwRI/MSSS Image processing by Björn Jónsson CC BY-NC-SA 2.0
Hypothesized internal structure of Europa
Hypothesized internal structure of Europa This graphic shows the hypothesized internal structure of Jupiter’s moon Europa. Much is unknown about the moon’s subsurface, but research from a team at Arizona State University suggests that the moon may have had a slow evolution. If it is the case, Europa may not have a fully formed metallic core or seafloor volcanism.Image: Kevin Trinh
Europa's variable plumes
Europa's variable plumes The Hubble Space Telescope has spotted a plume of water 200 kilometers above Europa's south polar region, but only at one position along its orbit, when the moon was at apoapsis. The bottom diagrams show a model for stresses across cracks in Europa's southern ice shell at different positions in its orbit. As the moon goes in its orbit around Jupiter, it gets squeezed pole-to-pole when close to Jupiter and returns to a more spherical shape when farther from Jupiter. Cracks near the moon's south pole are squeezed together when Europa is close to Jupiter and pulled apart when Europa is far from Jupiter.Image: Roth et al. 2013

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