Planning Approaches For Multi-spacecraft On-orbit Service Missions

On-orbit service?OOS?has been an important direction of space exploration and plays a key role in reducing the space mission cost and extending the spacecraft's life.Servicing multi-spacecraft in one mission can bring much more economic benefit,and the mission planning is the key of multi-spacecraft OOS mission.Multi-spacecraft OOS mission planning approaches are studied for solving three OOS problems.The main results in this dissertation are summarized as follows:1 A planning approach for the GEO multi-spacecraft closed-distance on-orbit observation mission using in-plane maneuvers is proposed.Considering the orbital-plane difference between the service spacecraft and the target spacecraft,a closed-distance observation dynamics model based on in-plane maneuvers is established for the non-coplanar on-orbit observation mission,using the in-plane modified orbital elements.The planning model for the GEO multi-spacecraft closed-distance on-orbit observation mission with one service spacecraft is built based on the dynamics model using in-plane maneuvers,and then is solved by a hybrid optimization approach.The results show that the optimal sequence always corresponds with the case with the smallest total relative transfer angle,the velocity increment increases with the increase of the total transfer angle,the total transfer angle is decided by the distribution of target spacecraft,and the plan using in-plane maneuvers can obviously save mission cost.2 A planning approach for the“multiple to multiple”closed-distance on-orbit observation mission of Walker constellation using in-plane maneuvers is proposed.The“multiple to multiple”closed-distance on-orbit observation means that multiple service spacecraft observe multiple target spacecraft.The planning model for the“multiple to multiple”closed-distance on-orbit observation mission using in-plane maneuvers is built,and is solved by a hybrid optimization approach.?1?The solutions of the optimal propellant cost show that the optimal number of service spacecraft tends to the largest value,and the transfer time of each orbital transfer tends to the largest value.?2?The solutions of the optimal time cost show that the number of target spacecraft being observed by each service spacecraft is the same as each other,and the transfer time of each orbital transfer tends to the smallest value.?3?The solutions of the multi-objective optimization show that the propellant decreases with the increase of the time cost,and the Pareto front has approached the extreme values given by the single-objective optimal solutions.3 A planning approach for LEO multi-spacecraft cooperative refueling mission considering J₂ perturbation and target's surplus propellant constraint is proposed.In the cooperative refueling mission,both the service spacecraft and target spacecraft have the ability to execute maneuvers,and all service positions are not fixed.The planning model for the LEO cooperative multi-spacecraft refueling mission considering the J2 perturbation and target's surplus propellant capability constraint is built based on a linear relative dynamic equation considering the J2 perturbation,and then is solved by a two-level hybrid optimization approach.Some major conclusions can be drawn.?1?With the increase of target spacecraft's structure mass,the number of service positions decreases,and the target spacecraft is willing to perform cooperative maneuvers when the target spacecraft's structure mass is much smaller than the initial mass of the servicer.?2?The model considering the J2 perturbation requires more propellant than the model not considering the J2 perturbation,and the extra propellant cost is used to eliminate the orbital-plane differences caused by different orbital-plane drafting rates under J2 perturbation.?3?The propellant cost is reduced effectively by using a cooperative rendezvous strategy.Multi-spacecraft OOS missions have been studied in this dissertation,and the corresponding planning models and optimization approaches are proposed.In addition,some engineering factors are considered,and then this study is closer to practical missions than previous studies.The proposed approaches and the obtained results can provide valuable reference for practical Multi-spacecraft OOS missions.