<h2>AAS 95-308</h2><h2>A Conceptual Automatic Landing System for Spacecraft Using Pulse-Modulated Propulsion</h2><h4>S.W. Thurman, Jet Propulsion Laboratory, H. Flashner, University of Southern California, Los Angeles, CA</h4><h2> Abstract </h2>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.
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