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  • Analytical solutions for manned lunar landing trajectories

    Paper ID



    • C. N. Shen


    Rensselaer Polytechnic Institute






    This paper deals with a set of guidance equations for powered descent in vacuum. Various papers on terminal guidance 1,2 are available in the literature. However, combined mid-course and terminal guidance without approximation is still a problem at the present time. In this article a continuous thrust program for a single engine is employed for the entire clesçent phase of a vehicle in a vacuum. The weight of a retro-rocket is generally proportional to its rated thrust. The optimization problem of the combined mass of fuel and engine is approached approximately. The guidance and control system can be carried by the space vehicle to eliminate the inherent delay of an Earth-bound radio command system (2.56 sec round trip). All necessary special computers will be sufficiently simple and small for space travel because all computational solutions are in closed algebraic form, thus enabling an astronaut to operate the vehicle and determine his own course if manual operation is preferred.