Low-thrust maneuvers near the libration points

The problem of the minimum-propellant optimal maneuver of a spacecraft equipped with a low-thrust propulsion system near the libration points of the earth-moon system is considered. Approximate analytical expressions involving the neglecting of Coriolis forces are obtained for the variational problem. For descent from orbits at the libration points or for approaching the libration points from neighboring points, the problem is similar to that of orbital rendezvous. Numerical examples show that for maneuver durations greater than or equal to 100,000 sec (compatible with the low-thrust assumption), the value of the acceleration due to thrust falls within the allowable limits.