<h2>AAS 95-333</h2><h2>The Optimization of Initial Inclination for a Desired Sun-synchronous Orbit</h2><h4>C. C. Chao and R. G. Gist,  The Aerospace Corporation, Los Angeles, CA</h4><h2> Abstract </h2>The major perturbation force which gradually destroys the sun-synchronous property is the deep resonance with the sun's motion.  The resulting drift in local time at ascending node may be as large as 35 minutes after three years.  This undesirable perturbation can be minimized by introducing a small bias in the initial inclination without having to perform stationkeeping maneuvers.  This paper examines the deep resonance effect and describes an algorithm of optimizing initial inclination for a given local time.  Results of the study show that sun-synchronous orbits with optimized initial inclination can maintain a local mean solar time with deviations less than 15 minutes for a period of five years.  Optimized initial inclinations for all values of local times were generated for the DMSP mission.  Sensitivities to atmosphere uncertainties and orbit insertion errors are discussed.
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