A Technique for Lunar Landing Site Selection by Earth-Based Control

The report describes the results of a study of the techniques, system dynamics, and component characteristics required to control the landing point of a lunar landing vehicle by manual control from earth. The controller is presented with a television picture of the landing area from which he selects the desired landing point and designates that point by transmitting an appropriate command to the landing craft. A vehicle -borne guidance system then controls vehicle attitude and thrust magnitude to cause a soft landing to occur at the desired point. System operation results in a soft landing even if no command is received.

An important aspect of the study is the consideration of means of compensating for earth-moon transmission time delay. The study shows that a continuous prediction of the landing point can effectively stabilize the entire earth-moon control loop and that additional compensation of the operator's display and controls will be required for precise accuracy. Various factors affecting stability and accuracy of the landing site selection system are evaluated and discussed.