Evolution of organic matter with subcritical water during the formation of icy moons.

Recent models and observations suggest that organic matter (OM) is a major compound of the refractory cores of the icy moons of the solar system. This OM would have interacted with large amounts of water only during the accretion and differentiation of these bodies (before/during the formation of the refractory core). Inside larger water-rich exoplanets, these interactions could have happened at conditions above the critical point of water, leading to the efficient dissolution of the OM and to the formation of specific alteration minerals and volatiles (as was shown in our previous experiments). However, during the formation of the smaller icy moons of the solar system, water is not expected to have reached a supercritical state. The evolution of the OM in these conditions remains largely unknown. We propose to use in situ powder and single-crystal XRD, on anvil cell samples of OM and water, to establish a comprehensive picture of the fate of OM during the formation of icy moons.