Dottorato in INGEGNERIA AERONAUTICA E SPAZIALE

Titolo della tesi: Characterization of Planetary Atmospheres and Interior Structures with Radio Science Data

The propagation of radio frequency signals transmitted from a spacecraft to a ground station is strongly affected by atmospheres and gravity fields, leading to perturbations in the signals frequency, amplitude, and phase. The objective of radio science is to analyze these variations to infer the properties of the planetary atmosphere or interior structure that generated them. This thesis is devoted to the development of new methodologies and tools to analyze radio science data and to interpret the derived measurements. Each method is presented in combination with a specific study case. A statistical technique is developed to analyze radio occultation data, enabling the derivation of the vertical profiles of atmospheric density, pressure, and temperature and the associated uncertainties from a set of radio science data. The proposed method is applied and validated by analyzing a radio occultation of the Mars Reconnaissance Orbiter at Mars. A different statistical approach based on Bayesian inference is proposed to characterize the interior structure of an icy moon by combining gravity and magnetic field measurements. This technique is applied to the case of Jupiter’s moon Europa to derive constraints on its interior. Finally, a methodology to model and study the gravitational effects of the atmospheres of Mars and Venus is presented. It is demonstrated that these perturbations preserve information on the interior of the planet through the response to the atmospheric pressure loading on the surface. Measurements of this coupling between the atmosphere and the interior structure derived by radio science data could provide additional constraints on the interior properties of the planet.