Spacecraft trajectory targeting by boundary-condition orbit fitting

The classical two-point orbit boundary-value problem is extended to permit the determination of any three of the four target parameters (altitude, downrange angle, velocity, and flight-path angle) given the fourth. A guidance algorithm based on this analysis is developed, and the results of a computer simulation for launch into LEO and for LEO-GEO transfer are presented in graphs and tables. Errors of less than 0.001 percent are achieved in most cases, with near-optimal Delta-v values.