Abstract
We investigate the structure and evolution of multiphase ice-ocean
interfaces (‘mushy layers’) and the implications for the geophysics and
habitability of ice-ocean worlds. Understanding the potential diversity
of these multiphase layers across solar system bodies provides insight
into the potential rates and mechanisms of heat and solute transport
between their respective oceans and ice shells - which remain largely
unconstrained. Additionally, variations in mushy layer properties may
drive diverse geophysical processes unique to individual bodies or that
may vary regionally on an individual icy world. We explore mushy layer
evolution by analytically solving for the thickness of a simplified
ice-ocean mushy layer system. We investigate two dynamic regimes, one
driven by molecular diffusion and one driven by convection of brine
within the mushy layer. We analyze the impact of gravity, thermal
gradient, and ocean composition on the thickness of mushy layers.
Additionally, a perturbation analysis is carried out to investigate the
existence of mushy layer steady states. We show that stable mushy layers
exist when ice shells are thickening, suggesting that mushy layers are
likely persistent and common features of growing ice shells and
accretionary regions of ice-ocean worlds.