The tides of Ocean Worlds

Past space missions have revealed the existence of liquid water beneath the surfaces of Jupiter's and Saturn's icy moons. The source of energy that sustains this liquid water remains a mystery. The most probable explanation is dissipative tides raised by the parent planet, heating the moons through friction. However, the exact mechanism by which tidal energy is converted into heat is not yet fully understood.

Tidal forcing of extraterrestrial oceans — Tides heat icy moons oceans through periodic stretching and bending of their solid layers (Illustration after May Jernigan).

Our team showed that inertial modes excited by tides and libration can amplify the viscous dissipation in the ocean of Enceladus, one of Saturn's moon (Rekier et al., 2019).

Although this dissipation is insufficient to close thr heat budget, tidally excited fluid modes have characteristic signatures observable from space that can be used to probe the interior of icy moons.

References

Rekier, J., A. Trinh, S. A. Triana, and V. Dehant, 2019, Internal Energy Dissipation in Enceladus’s Subsurface Ocean From Tides and Libration and the Role of Inertial Waves: Journal of Geophysical Research: Planets, 124, 2198–2212.