Road map to L₄/L₅ with a solar sail

This paper explores the capability of solar sails to transfer a probe from the displaced Sun-Earth L₁ and L₂ libration points to the region of practical stability (RPS) around the triangular equilibrium points L₄ and L₅. If the sailcraft arrives inside the RPS with zero synodical velocity, it will remain there with minor station keeping requirements. Moreover, the location of the RPS is ideal for space weather missions as the Sun can be observed from a different angle compared to spacecraft orbiting the L₁ point. The unstable manifolds of the displaced L₁ and L₂ points come close to these regions providing opportunities for natural transfer trajectories. By varying the solar sail orientation along the manifold, the dynamics can be altered and simple transfer trajectories that reach the RPS with few sail maneuvers are enabled. However, these trajectories are not optimal from a transfer time perspective, but can serve as suitable initial guesses for a direct optimization method to find minimum-time transfers between the displaced L₁ and L₂ points and the RPS at L₄ and L₅.