SOLAR SAILCRAFT MOTION IN SUN EARTH MOON SPACE WITH APPLICATION TO LUNAR TRANSFER FROM GEOSYNCHRONOUS ORBIT

A three-dimensional model of the dynamics of a solar sailcraft in the Earth-Sun-Moon system is presented. The model includes the following f eatures: (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 paramet ers; and (4) the development of attitude control equations for the sai l. A computer program based on the above model which includes a search routine is described. The program is used, together with a strategy f or searching through a four-dimensional parametric space of initial or bit parameters, to investigate the problem of transfer to the Moon fro m a geosynchronous orbit. Results are obtained for two types of lunar encounters and three values of the sailcraft's area to mass ratio. Plo ts are presented for the orbits of the sailcraft and the Moon for the lunar encounter and for post-encounter sailcraft trajectories. It is f ound that a close flyby of the Moon can take place in 63-67 days for a n area to mass ratio of 100 and that the type of lunar encounter can r esult in significantly different post-encounter sailcraft trajectories .