The Implementation of Maintaining Constant Distance Between Satellites in Coplanar Elliptic Orbits
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The Implementation of Maintaining Constant Distance Between Satellites in Coplanar Elliptic Orbits 1 Zhaozhi Tan2, Peter M. Bainunr' and Avaine Strong" Abstract A strategy for maintaining separation distances between several satellites in a coplanar elliptical orbiting constellation is developed. A possible scientific application of such a system would be in measuring the curl of the Earth's magnetic field by taking simultaneous measurements along the elliptical orbit. The strategy involves maneuvers which would cause small shifts in the direction of the four semimajor axes. With this approach for Keplerian type orbits, the separation distance between adjacent satellites remains within a few percent of the nominal separation distance. This paper emphasizes problems of implementation: 1. Initial deployment. It is assumed that the satellites are launched by a single vehicle. The method to distribute the satellites into their positions using the least maneuver energy is studied. 2. Maintenance of the separation distance. Since the mathematical model is nonlinear and time-variant, a nonlinear control law based on a Lyapunov function is applied to the osculating orbital elements of the daughter satellites. The simulation results with this control show that with perturbations (mainly caused by J 2) , the response to initial errors converges smoothly and the control energy spent is at a very low level.
Introduction The scientific objectives of the Earth observation program are becoming more autonomous and more ambitious; this has created needs for innovative technical approaches to achieving and maintaining constellation and formation flights of spacecraft. The trend to develop small low-cost spacecraft has led many to recognize the advantage of flying multiple spacecraft in formation to achieve the correlated instrumentation formerly possible only by placing many instruments on a single platform. 'Presented at the AAS/AIAA Space Flight Mechanics Meeting, Clearwater, Florida, 23-26 January, 2000. 2Senior Research Associate, Department of Mechanical Engineering, Howard University, Washington, DC 20059. 3Distinguished Professor of Aerospace Engineering, Department of Mechanical Engineering, Howard University, Washington, DC 20059; Fellow AAS. Fellow AIAA. "Graduate Assistant, Department of Physics, Howard University, Washington, DC 20059; presently, Assistant Professor, Department of Mathematics and Computer Science, Grambling State University, Grambling, LA 71245.
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Tan, Bainum, and Strong
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A study was conducted of proposed NASA and ESA constellation configurations which would measure and study upper atmospheric phenomena. The Auroral Cluster (Multiscale) System, the Distance Measurement System, the Orbiting Interferometer System, as suggested by NASA and available on NASA web pages for LEO missions together with the Solar Stereo System in heliocentric orbit were all considered as possible baseline or "strawman" configurations. In addition information was also obtained from the ESA web page on the proposed ESA Clu
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