A Lunar Landing Guidance System for Soft-Precision Landings

A logical development of a novel, minimum-complexity guidance system for precise and soft lunar landing is presented together with an evaluation of predominant error sensitivities. Selection of this minimum-complexity system is influenced by its ability to handle a wide range of initial condition, sensor, propulsion and control system errors with minimum fuel and accuracy penalty. The trajectory control technique allows excellent compromise between sensor requirements (e.g., Doppler and beacon tracking radar gimbaling), control system complexity and total fuel usage. Proof of performance is given in terms of analog and digital computer simulation results plus theoretical correlation. Results include specific application to the proposed Saturn V Lunar Logistic Vehicle. Design guides are evolved for system synthesis and for potential application to future missions. Demonstrated performance includes terminal maneuvers of 5 km with touchdown displacement errors of less than 200 meters and velocities of less than 4 meters/sec vertically and 1 meter/sec horizontally.