<h2>AAS 95-431</h2><h2>Comparison of Orbit Propagators in the Research and Development Goddard Trajectory Determination System (R & D GTDS). Part I:  Simulated Data</h2><h4>D. J. Fonte, Jr., Phillips Laboratory, Kirtland AFB, NM,  B. Neta, Naval Postgraduate School, Monterey, CA, C. Sabol, Phillips Laboratory, Kirtland AFB, NM, D. A. Danielson, Naval Postgraduate School, Monterey, CA, W. D. Dyar, Marine Corps HQ, Washington, D.C.</h4><h2> Abstract </h2>This paper evaluates the performance of various orbit propagation theories for artificial earth satellites in different orbital regimes.  Specifically, R&D GTDS's Cowell (numerical technique), DSST (semianalytical technique), SGP, SGP4, and Brouwer-Lyddane (analytic techniques) orbit propagators are compared for decaying circular (280 km altitude), low altitude circular (599 km altitude), high altitude circular (1336 km altitude), Molniya, and geosynchronous orbits.  All test cases implement a one orbital period differential correction fit to simulated data derived from a Cowell truth trajectory.  These fits are followed by a one orbital period predict with the DC solve-for vector.  Trajectory comparisons are made with the Cowell "truth" trajectory over both the fit and predict spans.  Computation time and RMS errors are used as comparison metrics.  The Unix-based version of R&D GTDS (NPS SUN Sparc 10) is the test platform used in this analysis.
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