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 the internal dynamics and evolution of this small Saturnian moon. In this study, we develop a new methodology to infer regional variations in crustal thickness using measurements of tidally-driven elastic strain that could be made in the future. As proof of concept, we recover thickness variations from synthetic finite-element crustal models subjected to diurnal eccentricity tides. We demonstrate recovery of crustal thickness to within ∼2 km of true values across the crust with ∼10% error in derived spherical harmonic coefficients at degrees l ≤ 12. Our computed uncertainty is significantly smaller than the inherent ∼10 km ambiguity associated with crustal thickness derived solely from gravity and topography measurements. Therefore, future measurements of elastic strain can provide a robust approach to probe crustal structure at Enceladus.
Copyright and License
© 2023. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Acknowledgement
This research was supported by the Future Investigators in NASA Earth and Space Science and Technology (FINESST) Program (80NSSC22K1318). We thank the Keck Institute for Space Studies (KISS) at the California Institute of Technology for organizing two workshops about “Next-Generation Planetary Geodesy” which provided insight, expertise, and discussions that inspired the research. We also thank Matthew Knepley, Brad Aagaard, and Charles Williams for providing valuable advice on how to modify PyLith for the simulations described in this work. A portion of this research was supported by a Strategic Research and Technology Development task led by James T. Keane and Ryan S. Park at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).
Data Availability
The data used in this study were generated using the software package PyLith (Aagaard et al., 2007, 2022). PyLith is an open-source finite element code for modeling geodynamic processes and is available on GitHub and Zenodo repositories (Aagaard et al., 2022). The specific PyLith version used in this study was v2.2.2. PyLith input files (including sample surface topography data), post-processing scripts, and selected output files for this work are available on (Berne et al., 2023a). A full version of the forward FEM code, a user manual, and the workflow for inferring thickness from strain described in the current work is also available on (Berne et al., 2023a). The mesh geometries utilized in this study were created using CUBIT (v15.2), a node-locked licensed software which is available through the developer Sandia National Laboratories (CoreForm, 2020; Skroch et al., 2019).
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Additional details
- ISSN
- 1944-8007
- National Aeronautics and Space Administration
- NASA Earth and Space Science and Technology Fellowship 80NSSC22K1318
- National Aeronautics and Space Administration
- 80NM0018D0004
- Caltech groups
- Division of Geological and Planetary Sciences, Seismological Laboratory, Keck Institute for Space Studies