The building blocks of life may have been surprisingly abundant in the early solar system around Jupiter, according to new research. A study published February 15, 2026, details how complex organic molecules (COMs) – essential for prebiotic chemistry – likely formed within Jupiter’s circumplanetary disk, the swirling cloud of gas and dust from which the Galilean moons, including Europa, Ganymede, and Callisto, emerged. This discovery has significant implications for the potential habitability of these icy moons, which are prime targets in the search for extraterrestrial life.
While COMs haven’t yet been directly detected on the surfaces of Europa, Ganymede, or Callisto, upcoming missions from the European Space Agency (ESA) – JUICE – and NASA, Europa Clipper, are equipped to search for them. Understanding where these molecules originated and how they survived the tumultuous formation of the Jovian system is crucial to interpreting any future findings. The research, led by Olivier Mousis and published in Astrophysics, focuses on the conditions within Jupiter’s circumplanetary disk (CPD) and the processes that could have led to COM formation.
Thermal Processing: The Dominant Formation Pathway
The study identifies two primary pathways for COM formation: thermal processing of ices and UV photochemistry. However, the research indicates that thermal processing, particularly of ammonia-carbon dioxide (NH3:CO2) ices, was the dominant mechanism. This process involves heating the ices, triggering chemical reactions that create more complex molecules. Researchers used a time-dependent model that couples the evolving CPD structure with the dynamics of icy particles of varying sizes and release times to assess these pathways. The efficiency of these processes is influenced by particle density, disk viscosity, accretion rate, and UV flux, all of which affect how long particles drift and are exposed to favorable conditions.
Previous research, including a study presented at the EPSC-DPS 2025 conference, also highlighted the importance of thermal processing in the warm phases of Jupiter’s CPD. This study, also led by Mousis, focused on the early, warmer phases of the disk, where elevated temperatures played a key role in molecular evolution. Laboratory experiments have demonstrated that these molecules can form in icy environments through UV irradiation and thermal processing.
Moon Formation and COM Preservation
The conditions under which each of Jupiter’s major moons formed likely influenced their ability to retain COMs. Existing models suggest that Europa’s accretion was relatively slow and prolonged, potentially allowing some COMs to survive incorporation into the moon’s icy structure. Ganymede and Callisto, however, likely formed under even cooler conditions, which would have been more conducive to preserving COM-rich material. This suggests that different moons may have different levels of organic complexity.
The research builds on previous work examining particle transport in protoplanetary disks (PPDs). A study published in Astronomy & Astrophysics in December 2024, by Benest Couzinou et al., demonstrated the potential for applying particle transport models used in PPDs to circumplanetary disks, further illuminating the role of COMs in moon formation.
Implications for Future Exploration
The findings provide valuable context for interpreting data from the upcoming JUICE and Europa Clipper missions. By understanding the likely composition of the material from which the Galilean moons formed, scientists can better assess the potential for habitability and the likelihood of detecting biosignatures. The research emphasizes the importance of considering both thermal and photochemical processes when evaluating the origins of organic molecules in icy environments throughout the solar system.
As we prepare for these missions to begin their investigations, the question of whether life could exist in the subsurface oceans of Europa, Ganymede, and Callisto remains one of the most compelling in astrobiology. The continued study of complex organic molecules and their formation pathways will be critical to answering this question.
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