Angular momentum analysis in the elliptic restricted three-body problem

In this paper, the angular momentum of the test particle during the flyby in the spatial elliptic restricted three-body problem (ERTBP) is investigated. We focus on the flyby around the small primary, and derive approximate expressions to depict the changes of the angular momentum and energy in this process. Numerical computation based on the Earth-Moon ERTBP shows that our expressions can well approximate the real angular momentum and energy processes during the flyby. Hence, the mechanical process of a flyby orbit in the ERTBP is uncovered in detail. Furthermore, we analyse the optimal regions to maximize the changes of the angular momentum and energy. In addition, the inclination of the test particle during the flyby is investigated through the approximate expression of the angular momentum. The optimal flyby condition to change the inclination is obtained and discussed.