AAS 95-308

A Conceptual Automatic Landing System for Spacecraft Using Pulse-Modulated Propulsion

S.W. Thurman, Jet Propulsion Laboratory, H. Flashner, University of Southern California, Los Angeles, CA

Abstract

Previous soft landers employed sophisticate throttleable rocket engines during terminal descent. The desire to perform such missions in the future using pulse-operated (on-off) engines is motivated by their lower cost and relative simplicity. In this paper a new propulsive pulse-modulation scheme, whose performance and robustness are established analytically, is used to design a conceptual automated landing system for robotic spacecraft. Principal components are a cluster of small thrusters and an aided-inertial guidance system. Guidance and attitude control are performed with the same thrusters. The operation of this system is illustrated via detailed six-degree-of-freedom computer simulation of a hypothetical Martian soft lander.