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Using the gravity field spectrum for icy satellite interior structure determination: the case of Europa with the Europa Clipper mission

Presentation #314.08 in the session Icy Satellites, Fields and Particles (Poster + Lightning Talk)

Published onOct 23, 2023
Using the gravity field spectrum for icy satellite interior structure determination: the case of Europa with the Europa Clipper mission

A better understanding of the interior structure of icy moons in our Solar System is necessary to answer fundamental questions about their formation, evolution, and habitability. Until now, insights on the interior layering, core structure, and density distribution have been expected to be derived from global-scale gravity measurements, such as the mass, the moment of inertia (from the degree-2 static gravity field), and the tidal gravity response. With the upcoming NASA Europa Clipper and ESA JUICE missions, we will obtain reliable estimates of the gravity field of Jupiter’s icy moons to higher degrees (shorter wavelengths).

In this work, we present a new methodology and investigate the efficacy of utilizing the measured gravity field amplitude spectrum as an additional constraint in the inversion of the interior structure of differentiated icy bodies. After introducing and discussing the general method, we focus on Europa by considering the predicted measurement accuracy of the Europa Clipper gravity and radio science investigation. We show that a Bayesian inversion of Europa’s interior which incorporates the measured gravity field spectrum offers much stronger insights on key geophysical parameters determining the interior structure of the body. In particular, it allows a reliable measurement of the hydrosphere thickness to within 10-20km uncertainty, while at the same time reliably estimating key characteristics of the core, the silicate mantle, and the ocean floor, which is not possible with the traditional approach. The presented approach provides new sensitivity to the seafloor topography and elastic thickness, and it gives a way of probing the heat flow from the silicate interior. Ultimately, these fundamental constraints will help evaluate the potential for habitability of Europa and its subsurface ocean.

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