Optimization of launch trajectory for SSO (sun synchronous orbit) based on adaptive transfer orbit

The optimal ascent trajectory design of the vehicle for Sun Synchronous Orbit (SSO) is an optimal control problem with strict inner and terminal constraints and variable final time; this is difficult for the optimal control theory. To solve this problem, firstly it is translated into a multi-parameter optimization problem, and then an adaptive integration module is presented to obtain a transfer orbit with altitude and velocity injection constraints automatically satisfied, and an impulse modified penalized function is introduced to deal with unsatisfied constraints. Finally, with the help of MATLAB integrated genetic algorithm (GA), the optimal ascent trajectory is obtained. A simulation example indicates that: the injection constraints of transfer orbit are met accurately, and those of SSO need a little modification in velocity magnitude. The obtained trajectories are consistent with actual engineering conditions, and have been approved by the administrative department for relevant industry.