Dynamics of Mixed Clathrate-Ice Shells on Ocean Worlds

Evan Carnahan , Steven D. Vance , Marc A. Hesse , Baptiste Journaux , Christophe Sotin (1)

1 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]

The habitability of oceans within icy worlds depends on material and heat transport through their outer ice shells. Previous work shows a methane clathrate layer at the upper surface of the ice shell of Titan thickens the convecting region, while on Pluto a clathrate layer at the base of the ice shell hinders convection. In this way, the dynamics of clathrate-ice shells may be essential to the thermal evolution and habitability of ocean worlds. However, studies to date have not addressed the dynamics that determine the location of clathrates within the ice shell. Here, we show that, in contrast to previous studies, clathrates accumulating at the base of the ice shell are entrained throughout the shell. Clathrates are stiffer than ice. As a result, entrainment slows convection and thickens the conductive lid across a range of ocean worlds, potentially preserving sub-ice oceans but limiting avenues for material transport into them.

Keywords: icy ocean worlds; ice shell; dynamics; methane clathrate; Titan; Pluto

Domains: Sciences of the Universe [physics]

Evan Carnahan, Steven D. Vance, Marc A. Hesse, Baptiste Journaux, Christophe Sotin. Dynamics of Mixed Clathrate-Ice Shells on Ocean Worlds. Geophysical Research Letters, 2022, 49, ⟨10.1029/2021GL097602⟩. ⟨insu-03663665⟩