Cosmic Oven: How Heat Baked the Building Blocks of Life on Jupiter's Moons express
Life may be hiding in the oceans beneath the ice of Europa, Ganymede, and Callisto. Its carbon-based building blocks perhaps baked before the moons were born — in a disk of gas and dust around a young Jupiter. This giant cosmic oven ran on slow frictional heating, not harsh ultraviolet light. Icy grains of ammonia and carbon dioxide, like dough, circulated in the warmth for months, turning into amino acids and sugars. The heating gently assembled molecules, without tearing them apart like UV light does.
When the disk cooled, the moons were born. Europa ended up in a cool spot, like on the bottom shelf of a fridge, while Ganymede and Callisto went into the freezer. The temperature kept the complex organics almost untouched. Soon, the JUICE and Europa Clipper probes will scan liquid water beneath the crust using spectrographs and check how well these cosmic loaves have baked.
Original abstract
as written by the authors arXiv:2602.14334
Europa, Ganymede, and Callisto are key targets in the search for habitability due to the potential presence of subsurface oceans. Detecting complex organic molecules (COMs), essential for prebiotic chemistry, is crucial to assessing their potential. Though COMs remain undetected on these moons, ESA's JUICE and NASA's Europa Clipper missions aim to fill this gap with their science payloads. This study explores the formation and transport of COMs within Jupiter's circumplanetary disk (CPD), a critical environment for the formation of the Galilean moons. Using a time-dependent model that couples the evolving CPD structure with the dynamics of icy particles of varying sizes and release times, we assess two primary COM formation pathways: thermal processing of ices and UV photochemistry. The results indicate that heating, particularly of NH3:CO2 ices, occurs efficiently before substantial irradiation, making it the dominant pathway for COM formation in the Jovian CPD. However, the relative efficiencies of these two processes are governed by particle density, disk viscosity, accretion rate, and UV flux, which collectively determine drift timescales and exposure to favorable thermodynamic environments. Existing models indicate that Europa's accretion was relatively cold and prolonged, possibly allowing some COMs to survive incorporation, whereas Ganymede and Callisto likely formed under even cooler conditions conducive to preserving COM-rich material. These results highlight the potential inheritance of complex organics by the Galilean moons and offer a framework for interpreting upcoming compositional data from JUICE and Europa Clipper.
Icy crumbs of ammonia and carbon dioxide turn into sugars and amino acids in warmth, just as easily as regular sugar becomes caramel.
The search for organic molecules on icy moons echoes the plot of the film 'Europa' (2013) — but in reality, probes are already on their way.