Orbit Design for Earth-orbiting Formation Flying Satellites Aligned in a Straight Line toward a Celestial Target

Abstract

Formation flying (FF), which employs multiple satellites to achieve missions that are difficult to be realized with a single satellite, is becoming an important technology. Considering some FF missions such as exo-planet observation missions employing occulters, or X-ray telescope/interferometer missions, in which satellites have to be aligned in a straight line toward celestial targets, this paper studies the design of two satellites’ orbits and the schedule for observing multiple targets. In the proposed optimization method, the whole observation sequence will be divided into two phases: observation of the same target for several orbits, and the orbit maneuver to change observation targets. The relative orbits of two satellites for these two phases are optimized in terms of ΔV. Optimization results showed that along-track and cross-track formations require significantly small ΔV. By employing these results, the whole mission sequence to observe multiple targets is optimized by considering all the design parameters, including even target observation order. The results showed that a reasonable “Pareto-curve” was obtained in terms of total time and ΔV, including a better solution in both criteria than the ones obtained using the method in literature.