Propagazione orbitale numerica e modellazione delle perturbazioni per satelliti in orbita terrestre mediante Orekit

Accurate orbit propagation is essential for space applications such as geodesy, Earth observation, and space surveillance. This thesis investigates the numerical propagation of six passive geodetic satellites (Larets, LARES, Ajisai, Starlette, Stella, and WESTPAC-1) and the Sentinel-3A and Sentinel-3B satellites using the open-source Orekit library. The analysis evaluates the contribution of the main gravitational and non-gravitational perturbations by progressively increasing the complexity of the dynamical model. Propagated trajectories are compared with independent reference ephemerides in the Radial, Along-track, and Cross-track (RTN) frame, using maximum absolute errors and root-mean-square errors as performance metrics. The results show that the impact of perturbations depends on the satellite’s orbital and physical characteristics. Tidal effects are particularly evident in the Cross-track direction, atmospheric drag mainly affects the Along-track component, and solar radiation pressure exhibits satellite-dependent behaviour. Differences between reference ephemerides also influence the assessed propagation errors. Overall, the study highlights the importance of accurately modelling perturbing forces to improve orbit propagation performance across different classes of Earth-orbiting satellites.