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The Tides of Enceladus' Porous Core
Marc Rovira-Navarro1,2,3, Richard F Katz4, Yang Liao5
1Department of Ocean Systems NIOZ Royal Netherlands Institute for Sea Research Yerseke The Netherlands.
Journal of Geophysical Research. Planets
|July 22, 2022
Summary
The porous core of Saturn's moon Enceladus may generate geological activity if it has low rigidity and viscosity. Its overlying ocean limits energy dissipation from pore fluid flow, suggesting the core itself is the primary source.
Area of Science:
- Planetary Science
- Geophysics
- Astrophysics
Background:
- Enceladus exhibits hydrothermal activity, suggesting a porous core.
- Tidal dissipation in the core is a proposed energy source for geological activity.
- Previous models assumed viscoelasticity, not poroviscoelasticity, for the core's tidal response.
Purpose of the Study:
- To analyze the poroviscoelastic tidal response of Enceladus' core.
- To better constrain the distribution of tidal dissipation within Enceladus.
- To investigate the role of pore pressure and fluid flow in tidal dissipation.
Main Methods:
- Applied Biot's theory of poroviscoelasticity to a self-gravitating, spherically symmetric moon model.
- Developed a new framework for analyzing tidal response in porous celestial bodies.
- Investigated the influence of core-ocean boundary conditions on tidal dissipation.
Main Results:
- The overlying ocean significantly hinders Darcian porous flow within the core.
- The Darcian contribution to tidal dissipation is negligible due to ocean buffering.
- Enceladus' core can only be the primary source of geological activity if it possesses low rigidity and very low viscosity.
Conclusions:
- Poroviscoelastic effects are less significant than previously assumed for Enceladus' tidal dissipation.
- The core's properties (low rigidity, low viscosity) are critical for it to be the source of geological activity.
- Future missions measuring tidal phase lags could validate these findings.
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