Effects of perturbations on lunar satellite orbits at different altitudes

Aim. Lunar missions need comprehensive knowledge of the perturbation effects of: (1) deviation of moon from being spherical, (2) Earth, (3) sun; the introduction of the full paper points out that, since, to our knowledge, only fragmentary information exists in the open literature^{[2, 3]}, this paper intends to provide the comprehensive knowledge needed. We explain our research results in sections 1 and 2. Section 1 studies the magnitudes of changes in lunar non-spherical perturbation, earth perturbation and sun perturbation at different altitudes. Section 2 analyzes the effects of the three perturbations on the changes in orbital elements and perilune altitudes; it also simulates their effects on orbital elements at different altitudes; the simulation results, given in Figs. 2 through 5 and Tables 2 and 3, and their analysis show preliminarily that: (1) the higher the altitudes of lunar orbits, the greater are the changes in eccentricity, semi-major axis and perilune altitude caused by neglecting the earth perturbation, while the effects of lunar non-spherical perturbation decrease; (2) when the altitude is above 5300 km, the effect of sun perturbation can not be ignored.