Nonlinear Guidance for a Transfer Orbit to the Moon

The purpose of this work is to present a nonlinear guidance algorithm for spacecraft navigation that can be applied in any mission scenario. This approach allows to reliably estimate the navigation Delta-V (DV) budget and obtain a more accurate and reliable orbit insertion performance. The proposed nonlinear guidance algorithm is applied for a lunar mission scenario, focusing on the transfer orbit up to lunar orbit injection. The key performance parameters under analysis include the navigation DV budget for the mission and the orbital parameters scattering at arrival with respect to the targets. To perform a realistic and reliable analysis, the study takes into account the main factors that affect spacecraft navigation, namely the accuracy of the launcher insertion, the manoeuvres execution errors, and the knowledge of the spacecraft state. As a last step, we investigate how the navigation performances are affected by the ground station operations schedule, namely by the orbit determination arc and the flight dynamics operations cycle. The duration of the orbit determination arc is related to the observation time window used to estimate the spacecraft's position. The flight dynamics operations cycle consists of the timing for the ground infrastructure procedures, such as orbit determination, manoeuvres planning, and TT&C.