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Abstract
In April of 2010, control of cable communications satellite Galaxy 15 was lost. The satellite remained uncontrolled, drifting in free orbit, for over nine months before control was resumed. During its drift, Galaxy 15 continued to transmit position data. These drift position data offer a unique opportunity to investigate the forces in the geostationary orbit regime. The purpose of the project that is described in this report was to compare the empirical data from Galaxy 15’s uncontrolled period with a high-fidelity geosynchronous orbit dynamic model. The dynamic model was constructed with Matlab ®, and was verified by use of the satellite’s ephemerides over a full month of propagation data. The model was then run for each perturbation force, simulated separately, in order to find the specific effects of each perturbation force. The project report contains an analysis of the forces, and a conclusion concerning how each force affects the orbit regime. Each force examined is found to have a large effect in at least one classical direction.