Solar sail transfer trajectory from L1 point to sub L1 point

Solar sail working at a sub L1 point can increase the warning time for geomagnetic storms. This paper proposes a new transfer profile from the L1 periodic orbits to the sub L1 point or periodic orbits around it. Both the invariant manifolds of the periodic orbits around L1 point and sub L1 points are used to design the transfer trajectory. The spacecraft evolves along the unstable manifold of the L1 periodic orbit during pre-sail-deployment phase and flies to the target sub L1 periodic orbit along its stable manifold after sail deployment. Previous to the transfer trajectory design, the existence of this kind of transfer trajectory is checked from the point of view of energy. Then, the transfer trajectory design problem is parameterized and the design parameters are optimized to achieve the transfer trajectory, both 2-dimension and 3-dimension cases. The influences of different design parameters on the transfer trajectory are investigated for 2-dimension cases. Several 3-dimension transfer trajectories are used to illustrate the differences from 2-dimension cases.