Using Tidally-Driven Elastic Strains to Infer Regional Variations in
Crustal Thickness at Enceladus
Abstract
Constraining the spatial variability of the thickness of the ice shell
of Enceladus (i.e., the crust) is central to our understanding of its
thermodynamics and habitability. In this study, we develop a new
methodology to infer regional variations in crustal thickness using
measurements of tidally-driven elastic strain. As proof of concept, we
recover thickness variations from synthetic finite-element models of the
crust subjected to diurnal eccentricity tides. We demonstrate recovery
of crustal thickness to within ~2 km of true values with
< 0.2 km error over spherical harmonic degrees l ≤ 12
(corresponding to half-wavelengths ≥ 60 km). Our computed uncertainty is
significantly smaller than the inherent ~10 km ambiguity
associated with inferring variations in crustal thickness solely from
gravity and topography measurements. We therefore conclude that
measuring elastic strain provides a relatively robust approach for
probing crustal structure at Enceladus.