Europa is not supposed to look the way it does. Jupiter's icy moon is scarred by a chaotic patchwork of fractured terrain, criss crossed ridges, and disrupted surface regions that suggest something dynamic is happening beneath its frozen shell. Scientists have long suspected that a vast liquid ocean, kept warm by the gravitational kneading of Jupiter's enormous gravity, lies hidden beneath that ice. Now, a new study using the James Webb Space Telescope is adding a crucial piece to the puzzle, and the implications reach right to the heart of astrobiology.
The surface of Europa captured by Galileo spacecraft in the late 1990s (Credit : NASA)
The research, led by Gideon Yoffe and colleagues, applied a sophisticated technique called spectral decomposition to JWST observations of Europa's leading hemisphere. Think of it as chemical fingerprinting at a distance. Every molecule absorbs and reflects light at characteristic wavelengths, leaving a distinctive signature that a sensitive enough telescope can detect and map. By analysing nine separate spectral bands covering water ice, carbon dioxide, and other compounds, the team was able to unpick the different chemical layers on Europa's surface and reconstruct where each one sits.
They found that carbon dioxide, which had already been detected on Europa before, concentrated in a geologically chaotic region called Tara Regio, an area where the surface appears to have been broken up and refrozen, pulling material from deeper down. The working assumption was that this was a localised feature but the new analysis suggests otherwise. The carbon dioxide enrichment extends well beyond Tara Regio, sprawling across multiple regions of chaos terrain in a broad, lens shaped distribution. Crucially, wherever the carbon dioxide is richest, the ice itself shows unusual textural properties, as if the surface has been reworked from below.
A series of images of Europa in different wavelengths by the James Webb Space Telescope. The different wavelengths show the presence of different forms of carbon dioxide on Europa (Credit : NASA)
That combination, the pattern of the carbon dioxide and the anomalous ice texture points toward something more interesting than simple surface chemistry driven by radiation. The team's findings suggest the distribution of volatiles on Europa reflects not just where material is deposited, but where the surface is best able to hold onto it. The ice microstructure itself may be determining what gets retained and where. That's a subtler and more physically rich picture than the simple story of carbon dioxide arriving and staying put.
Carbon dioxide is one of the six elements considered essential for life as we know it. If the surface deposits are originating from the subsurface ocean as the concentration in geologically young chaos terrain implies, then that ocean contains carbon. It is also in chemical communication with the surface, exchanging material across the ice in ways we are only beginning to understand and explore.
Europa Clipper, NASA's dedicated mission to Jupiter's moon, will begin its close flybys in 2031. When it does, the chemical map being assembled by JWST will tell it exactly where to look.
Source : Spectral Decomposition Reveals Surface Processes on Europa
