Launch vehicle and power level impacts on electric GEO insertion
32nd Joint Propulsion Conference and Exhibit
Solar Electric Propulsion (SEP) has been shown to increase net geosynchronous spacecraft mass when used for station keeping and final orbit insertion. The impact of launch vehicle selection and power level on the benefits of this approach were examined for 20 and 25 kW systems launched using the Ariane 5, Atlas lIAR, Long March, Proton, and Sea Launch vehicles. Two advanced on-board propulsion technologies, 5 kW ion and Hall thruster systems, were used to establish the relative merits of the
... ve merits of the technologies and launch vehicles. GaAs solar arrays were assumed. The analysis identifies the optimal starting orbits for the SEP orbit raisinffplane changing while considering the impacts of radiation degradation in the Van Allen belts, shading, power degradation, and oblateness. This use of SEP to provide part of the orbit insertion results in net mass increases of 15 -38% and 18 -46% for one to two month trip times, respectively, over just using SEP for 15 years of north/south station keeping. SEP technology was shown to have a greater impact on net masses of launch vehicles with higher launch latitudes when avoidance of solar array and payload degradation is desired. This greater impact of SEP could help reduce the plane changing disadvantage of high latitude launch sites. Comparison with results for 10 and 15 kW systems show clear benefits of incremental increases in SEP power level, suggesting that an evolutionary approach to high power SEP for geosynchronous spacecraft is possible. '" including the Ariane 5, Atlas lIAR, Long March. Proton, and Sea Launch. Two payload power levels, 20 and 25 kW, were assumed available for the electric propulsion orbit transfer. These powers are consistent with expected growth in geosynchronous communications satellite power over the next 5 -7 years. As in the previous study, the mass impact of replacing some portion of the chemical apogee propulsion system with either a Hall thruster or ion thruster system is established. Arcjet thrusters were not evaluated because previous results showed they were not competitive with the higher lsp systems. 7 The electric system also performs fifteen years of station keeping. Throughout the study, conservative projections for these propulsion systems were used in order to make the results applicable to next generation missions.