Near-Earth Asteroid Warning and Defense Trajectory Design Based on Sun-Earth Halo Orbit

Near-Earth asteroids (NEAs) pose a major potential threat to the safety of the Earth and plenty of NEAs have not been discovered. Nowadays, asteroid observation is mainly carried out by ground-based observation platforms, which cannot monitor asteroids that come from the direction of the Sun. This study proposes to deploy a short-term warning and defense system on Sun-Earth L1 Halo orbits, which mainly provides short-term warning and defense of NEAs from the direction of the Sun. The capabilities of the short-term warning defense system are analyzed. The impact of asteroid size on the short-term warning time and distance of the system is firstly studied. Then, the transfer trajectory for short-term defense is designed under mission constraints. This paper considers the case of the Chelyabinsk meteoroid that came from the direction of the Sun and was not detected by ground-based systems. Besides, the defense effect of the system for asteroids with different diameters is compared. The results show that the system can provide an effective short-term defense against certain asteroids approaching from the direction of the sun. However, as the mass of the asteroid increases, the impact effect will gradually decrease. The analysis of this study provides a feasible and valuable reference scheme for the NEAs defense.