Low-energy lunar transfer design using high- and low-thrust on ballistic capture trajectories

The paper considers the problem of calculating the low-energy transfers of a spacecraft (SC) to the Moon into a ballistic capture orbit within the ephemeris model of four-bodies, including: Earth, Moon, Sun and spacecraft. The transfer is carried out using a transit trajectory in the vicinity of one of the collinear libration points L1 or L2 of the Earth-Moon system. The use of a transit trajectory makes it possible to reduce fuel costs for the transfer due to the dynamics of spacecraft movement in the Earth-Moon system. Another way to increase the efficiency of lunar missions is to use electric propulsion system (EPS) with a high specific impulse for their implementation, which can significantly reduce fuel costs. But low-thrust trajectories have a slow change in the energy constant, so a typical trajectory between the near-Earth and lunar orbits enters the Moon's SOI (sphere of influence) near the libration point L1. To use the effects of the three-body problem, one can include in the trajectory movement along invariant manifolds of libration points (or halo orbits), since on their basis it is possible to obtain transit trajectories of ballistic capture. The use of EPS leads to a significant increase in the duration of the flight to the Moon from near-Earth orbits. To reduce the flight duration when moving near the Earth, an upper stage can be used to enter an intermediate orbit. Thus, three sections are considered on the trajectory: a high-thrust section, a low-thrust section, and passive movement along the transit trajectory of a temporary capture. A method for solving the problem is proposed, which consists in determining the appropriate transit trajectory and calculating the optimal transfer of the spacecraft from the initial near-Earth orbit to the transit trajectory to the Moon using a combination of high- and low- thrust. Numerical examples of the calculation of low-energy trajectories to the circumlunar orbit of temporary capture with optimization of the point of entry onto the transit trajectory are given. The dependence of the flight duration and mass delivered to the Moon on the parameters of the intermediate orbit is obtained. Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.