New insights into temperature-dependent ice properties and their effect on ice shell convection for icy ocean worlds

TL;DR

This study introduces a new thermal conductivity model for ice, demonstrating its impact on ice shell stability and dynamics on icy ocean worlds like Europa, with implications for understanding surface features and habitability.

Contribution

We propose a revised thermal conductivity model for ice that accounts for temperature dependence, affecting ice shell stability and response timescales in planetary environments.

Findings

Increased thermal conductivity stabilizes Europa's ice shell.

Temperature-dependent specific heat reduces energy storage in the ice shell.

Model adjustments explain surface features like chaotic terrains.

Abstract

Ice shell dynamics are an important control on the habitability of icy ocean worlds. Here we present a systematic study evaluating the effect of temperature-dependent material properties on these dynamics. We review the published thermal conductivity data for ice, which demonstrates that the most commonly used conductivity model in planetary science represents a lower bound. We propose a new model for thermal conductivity that spans the temperature range relevant to the ice shells of ocean worlds. This increases the thermal conductivity at low temperatures near the surface by about a fifth. We show that such an increase in thermal conductivity near the cold surface can stabilizes the ice shell of Europa. Furthermore, we show that including temperature dependent specific heat capacity decreases the energy stored in the conductive lid which reduces the response timescale of the ice shell to thermal perturbations by approximately a third. This may help to explain surface features such as chaotic terrains that require large additions of energy to the near-surface ice.