Analysis of gravity and rotation measurements using probabilistic inference of planetary interior for the design of geodesic experiments : application to icy moons
(2025)
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- Abstract
- This work addresses the internal structure characterization of outer solar system icy satellites, emphasizing the gravity science (GS) experiment design for future missions. We identify that traditional mission planning, driven by engineering constraints, is often limiting and necessitates iterative redesigns to meet scientific objectives. To overcome this, we apply a novel "reverse mapping" approach focusing on desired scientific outcomes—specifically key interior parameter uncertainties—to determine required instrument performance and trajectory requirements. Our methodology combines the well established Precise Orbit Determination (POD) and Bayesian inference techniques. We validate this strategy through three distinct case studies. First, we validate our POD pipiline by replicating Cassini's Titan gravity field results. Second, regarding Juno's Io flybys, we highlight the limitations of designs not optimized for specific science objectives, showing that, given the nominal experiment design, the radiometric data alone are insufficient to constrain the moon's interior. Third, for the Uranus Orbiter and Probe (UOP), we demonstrate that a well-designed tour significantly enhances science return. We show that while the nominal X-band tour cannot resolve high-degree zonal harmonics ($J_6-J_{10}$) precisely, achieving these objectives is possible with an upgraded Ka-band radio link and specific polar trajectory optimization during orbit insertion. A primary contribution of this thesis is applying the "reverse mapping" framework to the major Uranian satellites: Miranda, Ariel, Umbriel, Titania, and Oberon. By simulating thousands of interior models, we construct "lookup tables" mapping geodetic measurement precisions—specifically Moment of Inertia, tidal Love number $k_2$, libration amplitude, and obliquity—to key interior parameter uncertainties. A crucial finding is that while determining ice shell thickness and rock-to-ice mass ratio is feasible with proposed UOP architectures, detecting subsurface oceans remains challenging due to difficulty measuring the tidal Love number ($k_2$) with limited flyby data. For instance, we show that determining Ariel's ocean thickness with 30% uncertainty requires measurement precisions exceeding current strategies. To address orbital remote sensing limitations, we investigate a complementary in situ approach using a 6-Degrees-of-Freedom (6DoF) motion sensor, the PIONEERS instrument. We demonstrate that a high-performance surface sensor can measure tidal and centrifugal accelerations precisely enough to distinguish differentiated from ocean-bearing interiors for the five major Uranian moons. Overall, this research establishes a quantitative methodology for science-driven mission design, ensuring that future ocean world exploration is optimized to address fundamental questions regarding habitability and internal dynamics.
- Affiliations
UCLouvain SST/ELI/ELIC - Earth & Climate
Citations
Filice, V. (2025). Analysis of gravity and rotation measurements using probabilistic inference of planetary interior for the design of geodesic experiments : application to icy moons. https://hdl.handle.net/2078.5/270611