Fuel-optimal trajectory design using solar electric propulsion under power constraints and performance degradation

The fuel-optimal transfer trajectories using solar electric propulsion are designed considering the power constraints and solar array performance degradation. Three different performance degradation models including linear, positive and negative exponential degradations are used in the analysis of three typical rendezvous missions including Apophis, Venus and Ceres, respectively. The optimal control problem is formulated using the calculus of variations and Pontryagin's maximum principle, which leads to a bang-bang control that is solved by indirect method combined with a homotopic technique. In demonstrating the effects of the power constraints and solar array performance degradation on the power budget and fuel consumption, the time histories of the power profile and the fuel consumptions are compared for the three missions. This study indicates that it is necessary to consider the power constraints and solar array performance degradation for the SEP-based low-thrust trajectory design, espacially for long-duration outbound flights.