Bounded trajectory design and self-adaptive maintenance control near non-synchronized binary systems comprised of small irregular bodies

Motions of spacecraft in non-synchronized binary asteroid systems are facing significant dynamics problems due to the irregular-shaped primaries and time-varying gravitational field. This paper presents a novel method for the design and maintenance of bounded trajectory in the vicinity of non-synchronized binary systems. A non-synchronized model with considering both the planar full two-body problem and the elliptic restricted three-body problem is developed for the bounded motion design. This model can better reflect the properties of motion in non-synchronized binary systems. Based on this non-synchronized model, bounded motions are designed with predetermined stability using the modified grid search and two-level correction strategy. Further, considering the model uncertainty and unmodeled perturbations in the high-fidelity model, a self-adaptive control method is proposed to maintain the trajectories. Simulations for the binary asteroid 1999 KW4 validate the stability and robustness of the proposed controller. Compared with periodic orbits using the synchronized model, the proposed strategy by taking the bounded trajectories as reference trajectories can effectively improve the tracking accuracy and reduce the fuel consumption. This provides a more effective solution for mission trajectory design in future explorations to binary asteroid systems.