Research On Orbit Injection Strategy Of Integrated Spacecraft

Design of a spacecraft with the capability of rapid response is the development trend of the low cost small satellite technology. It is also consistent with the requirement of the space emergency capability, protection of national security and winning the information war of our country. In recent years, domestic and foreign scholars proposed the concept of integrated spacecraft. It mainly includes modified launch mode, reuse of electronic equipment and modular design. In the modified mode, achievement of the maximum payload to orbit is the key technology in the development of integrated spacecraft. This paper studies the orbit injection strategy of the integrated spacecraft.As the integrated spacecraft process in orbit flight path at low altitudes, the atmosphere drag is large. Therefore, this paper focus on the impact of the atmosphere drag, and hence setting lower bound of the trajectory height and introduction of the atmospheric drag to vehicle dynamics equations are performed. By doing this, the accuracy and reliability of the orbit injection are improved.According to the selection of the type of propulsion system, impulsive and finite thrust strategies for orbit injection are studied. For the impulsive thrust case, the times of the thrust and the ignition points are studied, and a fast algorithm of modification to the atmospheric drag is proposed. For the finite thrust case, in terms of the difference of the ignition times of the engine, continuous and piecewise continuous thrust strategies for orbit injection are studied respectively. In which the study mainly focus on the impact of thrust magnitude on the orbit injection for the continuous thrust case, while the study mainly focus on the impact of times of the thrust on the orbit injection for the piecewise continuous thrust case. In addition, the small initial velocity case for the finite thrust strategies for the orbit injection is investigated in detail in this study, the solution of choosing the initial trajectory angle to this problem is presented.In the analysis of the finite thrust strategy, the orbit injection problem is transformed to the two-point boundary value problem (TPBVP). Direct allocation of non-linear programming method is employed to solve TPBVP. A large number of simulation results indicate that the method is effective.