Solar sailcraft motion in Sun-Earth-Moon space with application to lunar transfer from geosynchronous orbit

Abstract

A three-dimensional model of the dynamics of a solar sailcraft in the Earth-Sun-Moon system is presented. The model includes the following features: (1) the derivation of a unit vector describing the direction of the resultant radiation force for a spectrally reflecting sail; (2) the derivation of equations of motion for the sailcraft and the Moon in spherical co-ordinates; (3) the derivation of generalized equations for the initial conditions of the sailcraft in terms of orbit parameters; and (4) the development of attitude control equations for the sail. A computer program based on the above model which includes a search routine is described. The program is used, together with a strategy for searching through a four-dimensional parametric space of initial orbit parameters, to investigate the problem of transfer to the Moon from a geosynchronous orbit. Results are obtained for two types of lunar encounters and three values of the sailcraft's area to mass ratio. Plots are presented for the orbits of the sailcraft and the Moon for the lunar encounter and for post-encounter sailcraft trajectories. It is found that a close flyby of the Moon can take place in 63–67 days for an area to mass ratio of 100 and that the type of lunar encounter can result in significantly different post-encounter sailcraft trajectories.