Semi-analytical acquisition algorithm for repeat-groundtrack orbit maintenance

In this paper, the orbit acquisition and maintenance strategies for the repeat-groundtrack orbit are investigated to maintain the ground track of the satellite within a certain range. Two kinds of orbital dynamics models are introduced to calculate the on-orbit state of satellite. One is the orbital propagation model which is of high fidelity and can approximately express the forces acting on the satellite. The other is the design model which is of low fidelity and utilized by the semi-analytical acquisition algorithm to yield the reference repeat-groundtrack orbit. Combining the differential correction and analytical expressions, the results computed by the semi-analytical acquisition algorithm are of relatively high precision compared with the genetic algorithm. At the same time, the computational burden of the semi-analytical acquisition algorithm is far less than the genetic algorithm. Based on the reference orbit, two orbit maintenance strategies which are designed for chemical and electric engines are put forward to correct the orbit in order to make the ground track of satellite shift in a certain range. The application to the Chinese-French Oceanic Satellite mission has well validated the feasibility of these two strategies. Simulation results have shown that the strategy designed for chemical engine can keep the ground track displacement within 200 m, while all the orbit points can possess sub-meter repeat distance through adopting the strategy designed for the electric engine, which satisfies the requirements of the Chinese-French Oceanic Satellite mission.