Mixed CH4-CO2 hydrates in large icy satellites

This proposal is a continuation of the proposal ES-1540, where we investigated mixed gas clathrates of CH4 and CO2 at low-pressure – high-pressure conditions of large icy satellites, in the framework in the ANR project “CAGES”. Mixed gas clathrates are expected to be abundant phases of large ocean worlds, and knowledge of their polymorphism is essential to understand the chemical evolution and astrobiological potential of these unique planetary bodies. However, our knowledge of the stability and structural properties of mixed clathrates at conditions relevant to the interiors of large icy satellites remains essentially unknown. Herein, we propose to finalize our exploration of the most chemically relevant, CH4-CO2, mixed gas hydrates at various P-T-composition conditions, by applying in-situ X-ray diffraction in cryostat-cooled diamond anvil cells.