Europa's Coupled Ice-Ocean System: Temporal Evolution of a Pure Ice Shell

TL;DR

This study models the growth and evolution of Europa's ice shell, considering heat fluxes, rheology, and internal heating, and proposes a method to infer ocean properties from ice thickness data.

Contribution

It introduces a comprehensive model of Europa's ice shell evolution and a novel method to estimate ocean heat fluxes from future ice thickness measurements.

Findings

Shell transitions from conduction to convection within 10^5 to 10^7 years.

Steady-state thickness may exceed Europa's surface age under certain conditions.

Proposes a method to infer ocean heat fluxes from ice thickness data.

Abstract

Europa's icy surface likely overlies an ocean, but the ice thickness is not known. Here we model the temporal growth of a Europan shell of pure ice subject to varying ice-ocean heat fluxes, ice rheologies, and internal heating rates. Both constant and viscosity-dependent internal heating rates are included, yielding similar results for particular viscosities. A growing shell starting from an ice-free initial state transitions from conduction to convection at O(10$^5$) to O(10$^7$) years, with thicknesses O(1-10) km. For low ice-ocean heat fluxes and larger viscosities, the time to reach a steady-state thickness exceeds the estimated age of Europa's surface, whence the shell may still be growing. We conclude by presenting a method for inferring ice-ocean heat fluxes and vertical ocean velocities from the ice-thickness measurements expected from the upcoming Clipper mission, assuming the shell is in a conductive steady state.