An evaluation of semianalytical satellite theory against long arcs of real data for highly eccentric orbits

Abstract : The objective of this thesis was to test the semianalytical satellite theory (SST) as implemented in the Charles Stark Draper Lab. version of the Goddard Trajectory Determination System against long arcs of real data of highly eccentric orbits. The real data consisted of a 9-year arc of NORAD element sets for NSSC 9829, the Soviet Molniya 2-17 spacecraft; an 18-month arc of element sets for NSSC 14095, the ESA Exosat; and an 18-month arc of NORAD observations and element sets for NSSC 13964, the Soviet Molniya 1-57 spacecraft. The uses of elliptical orbits and the need for long-term predictions are reviewed as is the application of artificial satellite theory to elliptical orbits, including a summary of previous applications of satellite theory to highly elliptical orbits. The overall test method involved: 1) Pre-processing NORAD data; 2) Determining an initial state using an SST DC; 3) Generating an SST prediction file; and 4) Evaluating the SST prediction. This study shows that the semianalytical theory results in very satisfactory predictions for orbits of high eccentricity. For Molniya-type orbits, the results obtained when using actual observational data were superior to the results obtained when using element sets. For orbits of even higher eccentricity, the SST results were still very satisfactory.