Probing the Icy Shell Structure of Ocean Worlds with Gravity–Topography Admittance

The structure of the icy shells ocean worlds is important for understanding stability their underlying oceans as it controls rate at which heat can be transported outward and radiated to space. Future spacecraft exploration (e.g., by NASA's Europa Clipper mission) will allow higher-resolution measurements gravity shape than currently available. In this paper, we study sensitivity gravity-topography admittance in preparation future data analysis. An analytical viscous relaxation model used predict spectra given different shell structures determined temperature-dependent viscosity a tidally heated, conductive shell. We apply these methods Enceladus. find that sensitive mechanisms topography support wavelengths estimate required performance resolve transitions between mechanisms. Airy isostatic unable accurately describe universally across all when thickness significant fraction body's radius. Our models suggest low spherical harmonic degrees are more thick with high tidal dissipation, may complement ice-penetrating radar constraining thickness. Finally, constrain dissipation within shell, would complementary demanding measurement phase lag.