Dynamic Integration of Clathrate Hydrates in the Thermal Evolution of Subsurface Oceans on Icy Moons

Subsurface oceans hosted by icy bodies in the outer Solar System—such as Europa, Ganymede, Enceladus, Titan, and even dwarf planets like Ceres and Pluto—are prime targets for astrobiological exploration due to their potential to sustain habitable environments. Accordingly, numerous space missions, including JUICE, Europa Clipper, Dragonfly, Dawn, and New Horizons, are designed to investigate the internal structures, thermal states, and chemical environments of these worlds. Recent studies have highlighted the critical role of clathrate hydrates, which exhibit lower thermal conductivity and higher viscosity than water ice, thereby significantly influencing heat transport (convection and conduction), rheological properties, and long-term ocean stability.
Building on the hydrate–ice mixing model (Miller et al., 2025), we aim to systematically incorporate the dynamic integration of clathrate hydrates into a time-dependent thermal evolution framework across a broad parameter space. Our model improvements focus on several key aspects. First, we will consider multiple scenarios for radioactive element abundances, including both long-lived and short-lived radionuclides, and examine how accretion and differentiation time affect internal heating histories. Second, the release and redistribution of methane and other volatile gases are dynamically coupled to core temperature evolution. Third, to extend the model to large icy moons such as Europa, Ganymede, and Titan, we will explicitly include tidal heating and account for high-pressure phases of ice and clathrate hydrates. Fourth, porosity evolution and radius changes are incorporated to explore potential implications for internal structure and surface morphology.
We will first apply the optimized model to Ceres as a benchmark case, exploring how different hydrate–ice mixing states affect its internal structure and the evolution of a potential subsurface ocean. Preliminary expectations suggest that clathrate hydrates may facilitate ocean formation and prolong ocean stability. The refined model will then be applied to Europa, Ganymede, and Titan, where the inclusion of hydrate layers is expected to reduce the energetic requirements for sustaining subsurface oceans, resulting in more physically consistent thermal and structural evolution scenarios.
These results can provide new insights into the chemical and physical controls on the evolution of icy ocean worlds and support the interpretation of forthcoming mission data.