Solar-sail invariant objects in the Sun-Earth system and transfers to the L5 region

Abstract

The development of solar-sail technology in combination with the rising interest in a mission to the Sun-Earth L5 region for heliophysics and the search for Trojan asteroids, raises the question of using solar sailing as the primary propulsion method to enable such a mission. This study therefore investigates different invariant objects and their properties in the neighbourhood of Earth and in the L5 region that could be used as departure and arrival conditions: equilibrium points, families of periodic orbits and families of invariant tori as well as the stable manifold of periodic orbits. Then, transfers between these invariant objects are studied using a hybridisation of different trajectory design techniques. A multi-objective genetic algorithm is applied to obtain near-feasible initial guesses, which are transformed into feasible transfers using a differential correction method. Through a continuation on the fixed time of flight, the differential corrector is subsequently used to reduce the transfer time. A pseudospectral optimisation method is finally taken at hand to obtain a smooth, continuous control profile, to, if possible, further reduce the transfer time. This approach results in fast solar-sail transfers between 391 and 1194 days, depending on the departure and arrival configuration and the assumed solar-sail technology. These results can serve as preliminary design solutions for a mission to the Sun-Earth L5 region.