Stability and Control of Translunar Earth Orbits.

Investigation of the problem of keeping a satellite in an orbit around the earth at translunar distances from the earth. The study concentrates on distances between 300,000 and 500,000 n mi, since in this range the earth's gravitational attraction is the dominant factor in producing acceleration of a satellite vehicle relative to the earth. The approach to the problem involves formulation of the general nonlinear equations of motion for an object under the gravitational attraction of the earth, sun, and moon. The solution of these equations is in terms of the variation of the resulting motion from a nominal unperturbed circular orbit, and is obtained by numerical integration of the equations of motion. Although cases are found in which the radial variations from a reference orbital radius of 300,000 n mi remain less than 50,000 n mi for as long as five years, it appears to be desirable to have an orbital control capability. 109 pp. Ref.