Escape trajectories exploiting multiple lunar gravity assists

Taking advantage of a gravity assist manoeuvre is a common strategy to achieve generally high Delta V without resorting to the consumption of propellant - thus increasing the transportable payload mass -, as the gained energy is provided by the gravitational pull of a celestial body. In this instance, lunar gravity assists stand out as an extremely competitive alternative to direct escapes when evasion from Earth's sphere of influence is considered. This study is aimed at investigating the opportunity provided by a multiple-gravity-assist-aided escape, by examining the possible Moon-to-Moon trajectories allowing two consequent gravity assist manoeuvres and the effect on the escape orbit, with the intent to link the characteristics of said final orbit (heliocentric flight-path angle and declination) to the maximum achievable specific mechanical energy (i.e. the obtainable escape velocity). After a brief introduction, the mathematical models adopted throughout the dissertation will be presented; a description of the methodology for the analysis of Moon-to-Moon orbits and lunar gravity assists will then be introduced in a dedicated chapter, followed by a presentation of the obtained results. The final chapter consists of conclusive remarks, in addition to the difficulties faced during the work activity and a brief discussion about possible future developments of the present study.