Escape maneuvers with lunar gravity assists

For spacecraft interplanetary mission, gravity assist manoeuvres are usually used because they allow to get generally high ∆V without have recourse to the consumption of propellant, but exploiting the energy provided by the gravitational attraction of a celestial body. This allows to improving the useful mass for a specific mission, for a modest increase in flight time. Thus, when evasion from Earth’s sphere of influence is considered, lunar gravity assist manoeuvers become a valid alternative to direct escapes. In this paper two consecutive gravity assist manoeuvres are considered and is researched the possible moon-to-moon trajectories that allow their. Af- terward, considering different spacecraft initial speeds relative to Moon, the effect on the escape orbit is analyzed, with the purpose to link the features of the latter – heliocentric flight-path angle and declination – to the maximum obtainable specific mechanical energy (i.e. the achievable escape velocity).