JpGU-AGU Joint Meeting 2020

Presentation information

[J] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS32] Gas hydrate in environmental-resource sciences

convener:Hitoshi Tomaru(Department of Earth Sciences, Chiba University), Akihiro Hachikubo(Kitami Institute of Technology), Shusaku Goto(Institute for Geo-Resources and Environment National Institute of Advanced Industrial Science and Technology), Atsushi Tani(Department of Human Environmental Science, Graduate School of Human Development and Environment, Kobe University)

[MIS32-07] Gas hydrates as a potential protector of subsurface oceans in icy worlds

★Invited Papers

*Shunichi Kamata1 (1.Faculty of Science, Hokkaido University)

Keywords:Subsurface ocean, Gas hydrate, Astrobiology

Subsurface oceans in icy worlds are most interested research targets in astrobiology. The presence of a subsurface ocean is suggested for many outer Solar System bodies, such as the Jovian icy satellite Europa, the Saturnian icy satellite Enceladus, and the icy dwarf planet Pluto. The major premise for life to appear in an such ocean is the long-term existence of the ocean. Previous theoretical studies have pointed out that there are two options for an ocean to avoid freezing: production of a large amount of heat inside the body due to tides and/or large depression of freezing point of the ocean due to an inclusion of a large amount of impurities. Both options, however, are unlikely to explain the current presence of a subsurface ocean in Pluto. Recently, we recognized a new generic mechanism for an ocean to avoid freezing: a layer of gas hydrates on the ocean can act as a strong thermal insulator. This mechanism not only theoretically explains the presence of Pluto's ocean but also indicates that even a less-heated icy body can also possess a subsurface ocean for a long time depending on the condition. Thus, there would be more long-term subsurface oceans than previously thought.