%0 Journal Article
%T Pluto¡¯s ocean is capped and insulated by gas hydrates
%J -
%D 2019
%R https://doi.org/10.1038/s41561-019-0369-8
%X Many icy Solar System bodies possess subsurface oceans. On Pluto, Sputnik Planitia¡¯s location near the equator suggests the presence of a subsurface ocean and a locally thinned ice shell. To maintain an ocean, Pluto needs to retain heat inside. On the other hand, to maintain large variations in its thickness, Pluto¡¯s ice shell needs to be cold. Here we show, by thermal evolution and viscous relaxation calculations, that the presence of a thin layer of clathrate hydrates (gas hydrates) at the base of the ice shell can explain both the long-term survival of the ocean and the maintenance of shell thickness contrasts. Clathrate hydrates act as a thermal insulator, preventing the ocean from completely freezing while keeping the ice shell cold and immobile. The most likely clathrate guest gas is methane, derived from precursor bodies and/or cracking of organic materials in the hot rocky core. Nitrogen molecules initially contained and/or produced later in the core would probably not be trapped as clathrate hydrates, instead supplying the nitrogen-rich surface and atmosphere. The formation of a thin clathrate hydrate layer cap to a subsurface ocean may be an important generic mechanism to maintain long-lived subsurface oceans in relatively large but minimally heated icy satellites and Kuiper belt objects
%U https://www.nature.com/articles/s41561-019-0369-8