A Phase-Based Approach to Satellite Constellation Analysis and Design

An approach to the performance analysis of a satellite constellation providing intermittent coverage of the earth is developed. The approach uses only the phasing of satellites in terms of mean anomaly and site hour angle as the independent variables. A study of the revisit phenomenon is carried out using the phase-based approach, yielding an efficient method for evaluating the revisit-interval quality of a constellation. Computer software implementing the method makes constellation studies possible on a personal computer, giving advantages over the traditional technique of propagating orbit equations. The method is applied to example problems, to demonstrate the effects of constellation design parameters on coverage performance. An algorithm is developed to design 'optimal' intermittent-coverage constellations to meet mission constraints, using the methods developed for revisit-interval evaluation. A 10-satellite constellation is optimized on a personal computer to provide intermittent regional earth coverage within stated mission requirements. Finally, a brief study is made of the current constellation design for the 'Iridium' worldwide cellular telephone system, to evaluate the design and propose possible improvements.