1:45 PM - 2:00 PM
[MIS11-01] An interior structure model of Pluto resolving its mysteries
Keywords:Pluto, Subsurface ocean, Gay hydrates
Here we propose a thin gas hydrate layer exists between the ice shell and a subsurface ocean, and it prevents freezing of a subsurface ocean. Gas hydrates act as a thermal insulator because of its low thermal conductivity. We perform numerical calculations of long-term thermal evolution and show that a warm ocean and a cold ice shell can be maintained for a long time and that the freezing of the ocean is ineffective. We also perform numerical calculations of long-term viscoelastic deformation and show that the significant viscous relaxation requires billions of years. Our proposal does not require large amounts of contaminants. Comets contain a few % of methane with respect to water, for example, and this concentration is sufficient for creating a thin gas hydrate layer prohibiting the ocean freezing. Some gas species are easily trapped in gas hydrates while others are not, and this selective trapping may explain a large difference in volatile compositions of comets and Pluto’s surface. The subsurface ocean maintenance mechanism we propose here would also be applicable to larger icy bodies other than Pluto. In addition, our proposal may explain the diversity of surface chemistry of Kuiper Belt Objects.