Solar influence on satellite motion near the stable earth-moon libration points

The motion pf a space vehicle in the vicinity of the stable earth-moon libration points has been studied using a model which includes the perturbing effects of the gravitational attraction and the radiation pressure of the sun The earth and the moon are assumed to move in circular orbits about their mass center, and the earth-moon orbit plane is assumed to be inclined at an angle of 5°9' to the ecliptic The differential equations of motion in a libration point centered coordinate system were integrated numerically to determine the behavior of the vehicle The results of the investigation indicate that, when the effects of the sun are included, the natural motions of a vehicle placed initially at LI or L$ will not remain near the respective point Although the vehicle does move on a trajectory about the libration point for at least 700 days, the influence of the sun causes the vehicle to move through wide departures from the libration point The effects of the solar-radiation pressure for several satellite area-to-mass ratios are studied and the impulse requirements necessary to force a vehicle to remain at L± or at a point near L± are detei mined