Concurrent Station Keeping and Momentum Management of Geostationary Satellites
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Concurrent Station Keeping and Momentum Management of Geostationary Satellites Sumeet Satpute1 · M. Reza Emami1,2
© American Astronautical Society 2019
Abstract This article discusses a convex-optimization-based planning method for a geostationary satellite to determine station keeping and momentum unloading maneuvers concurrently. The proposed optimization algorithm incorporates a dual-rate prediction model to address the time scaling difference between the coupled slow orbital and fast attitude dynamics. The use of combined prediction model in the optimization problem facilitates to include state constraints accounting for the desired orbital and momentum unloading requirements. Maneuver plans are determined by solving a convex optimization problem in a receding horizon control form. The main objective of the proposed algorithm is to minimize fuel consumption while managing the stored momentum, in order to maintain a satellite in a tight station keeping window and nadir pointing attitude configuration. Numerical simulations are performed to validate the proposed optimization algorithm in terms of fuel consumption and constraint enforcement. Keywords Concurrent maneuver planning · Geostationary satellites · Convex optimization · Nonintersecting thrusters · Electric propulsion system
Introduction Geostationary satellites are subjected to various perturbations that deviate the satellite’s desired orbital position. The changes in the north/south directions are caused
M. Reza Emami
[email protected]; [email protected] Sumeet Satpute [email protected] 1
Department of Space Engineering, Lule˚a University of Technology, Kiruna, Sweden
2
Institute for Aerospace Studies, University of Toronto, Toronto, Canada
The Journal of the Astronautical Sciences
by inclination variations of the satellite’s orbit under the effect of the gravity perturbations from the Sun and Moon, whereas the changes in the east/west directions are caused by the longitude drift due to the lateral forces arising from the Earth’s non-homogeneity and the non-zero eccentricity caused by the solar radiation pressure (SRP), ([21], chap. 8). In order to maintain the satellite confined to its desired longitude-latitude window defined by the geographical longitude, station keeping is required, which performs a series of orbit control maneuvers implemented by the onboard thrusters. Currently, most of the satellites are equipped with chemical thrusters, and use a “wait and see” station keeping strategy, i.e., maneuvers are carried out only when the position of the satellite reaches the boundary of the tolerance window, [6]. Such corrective maneuvers are calculated as impulsive ΔV s accounting for the secular variations in the orbit evolution, and then implemented using chemical thrusters, ([20], chap. 4); [16]. In recent years, electric propulsion systems have emerged as a viable alternative, since they provide high specific impulse that results in significant reduction of propellant mass, leading to lower launch-mass and/or more s
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