Andrade rheology in planetary science

Abstract

The anelastic reaction of planet-forming materials is successfully described by the Andrade rheological model, which presents an extension of the simple Maxwell rheology. In addition to the instantaneous elastic deformation and the long-term viscous creep, the Andrade rheology incorporates the transient creep in metals, ices, and silicates, and is able to explain the tidal parameters of planets even in cases, where the Maxwell model requires the assumption of unrealistically low mantle viscosities. In this work, we discuss the applications of the Andrade model in planetary science, the parameters used in the literature, and their justification by material science and geodesy. We also examine the topic of relating the empirical tidal parameters to the mantle viscosity of moons and terrestrial planets and assess the limitations resulting from the uncertainties in the rheological parameters. Our study illustrates the necessity for future measurements that would help to better calibrate the rheological models to conditions relevant to the deep interiors of planets and moons.