Determining the internal structure of planetary bodies from gravitational observations is a key challenge in planetary geophysics. Traditional gravity inversion methods suffer from non-uniqueness due to trade-offs between mass distribution and depth, limiting their ability to resolve internal layering. We present SynthGen, a forward-modelling code developed to simulate the gravitational response of planetary bodies using parametric, multi-layer interior models without any a priori assumption, like the hydrostatic equilibrium. SynthGen calculates gravitational potential, Free-Air, and Bouguer anomalies through spherical harmonic expansions, leveraging the SHTools library (Wieczorek and Meschede, 2018). It accommodates a wide variety of internal configurations, including homogeneous layers with user-defined densities, thicknesses, and topographic geometries of internal interfaces, such as spherical, ellipsoidal, random, or Bouguer anomaly-derived interfaces. The code can be used both predictively and diagnostically: about the latter, SynthGen performs parameter-space exploration constrained by total mass, moment of inertia, and shape, identifying best-fit interior models by minimising the misfit between observed and synthetic gravity fields using combined statistical metrics. We apply SynthGen to Mercury, using the HgM009 gravity model derived from MESSENGER data (Genova et al., 2023), and recover crustal thickness and core parameters consistent with recent independent geophysical estimates. In predictive mode, SynthGen generates synthetic gravity fields for planetary bodies where gravity data are not available or are still limited in resolution, such as Ganymede. These simulations can support the planning and optimisation of space missions. By integrating physical constraints, statistical validation, and flexibility in model design, SynthGen offers a robust platform for planetary interior studies, constraining interior structures from gravity measurements across a broad range of Solar System bodies.
SynthGen: A gravity field simulator for planetary interior modelling
Mitri, Giuseppe
2026-01-01
Abstract
Determining the internal structure of planetary bodies from gravitational observations is a key challenge in planetary geophysics. Traditional gravity inversion methods suffer from non-uniqueness due to trade-offs between mass distribution and depth, limiting their ability to resolve internal layering. We present SynthGen, a forward-modelling code developed to simulate the gravitational response of planetary bodies using parametric, multi-layer interior models without any a priori assumption, like the hydrostatic equilibrium. SynthGen calculates gravitational potential, Free-Air, and Bouguer anomalies through spherical harmonic expansions, leveraging the SHTools library (Wieczorek and Meschede, 2018). It accommodates a wide variety of internal configurations, including homogeneous layers with user-defined densities, thicknesses, and topographic geometries of internal interfaces, such as spherical, ellipsoidal, random, or Bouguer anomaly-derived interfaces. The code can be used both predictively and diagnostically: about the latter, SynthGen performs parameter-space exploration constrained by total mass, moment of inertia, and shape, identifying best-fit interior models by minimising the misfit between observed and synthetic gravity fields using combined statistical metrics. We apply SynthGen to Mercury, using the HgM009 gravity model derived from MESSENGER data (Genova et al., 2023), and recover crustal thickness and core parameters consistent with recent independent geophysical estimates. In predictive mode, SynthGen generates synthetic gravity fields for planetary bodies where gravity data are not available or are still limited in resolution, such as Ganymede. These simulations can support the planning and optimisation of space missions. By integrating physical constraints, statistical validation, and flexibility in model design, SynthGen offers a robust platform for planetary interior studies, constraining interior structures from gravity measurements across a broad range of Solar System bodies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
