Rapid Solar Sail Rendezvous Missions to Asteroid 99942 Apophis

摘要

Different concepts for eliminating the threat of collision with a near-Earth object have been suggested in recentnyears.Most of themrequire that a probe is inserted in orbit around the object to obtain accurate physical and orbitalndata. Asteroid 99942 Apophis is amember of the Aten group of asteroids, having orbital periods shorter than 1 year.nSuch an asteroid is used here as a practical example to investigate the characteristics of newmission concepts and as ancandidate for a potential space agency project aimed to tag an asteroid either for scientific purposes or for a deflectionnmission decision. The purpose of this paper is to investigate the potentialities offered by a solar-sail-based rendezvousnmission toward Apophis. In particular, rapid transfer trajectories are studied, that is,missions whose transfer timesnare less than one terrestrial year. We show that a realistic near-term mission option, with a transfer time of aboutn300 days, requires a solar sailwith a characteristic acceleration of 0:5 mm=s2n.Asquare solar sailwith a side of aboutn90mis needed for a payload of 50 kg, whereas a greater sailwith a side of 160mis called for with a payload of 150 kg.nThe solar sail performance is compared to that achievable with conventional propulsion systems.