Trajectory Diversion of an Earth-Threatening Asteroid via Massive Tether-Ballast System

Abstract

The risk of an impact between a large asteroid and the Earth has been deemed signicant enough to attract the attention of an increasing number of researchers and government ocials. Researchers have provided a large volume of information related to the location and mitigation of Earth-threatening asteroids. Congress directed NASA in 2005, via the George E. Brown, Jr. Near-Earth Object Survey Act, to provide an analysis of some of the alternatives proposed for both nding and mitigating threats. This paper focuses on a mitigation technique that was not included among the alternatives listed in the report, namely the use of a long tether and ballast mass to divert an asteroid. In a previous study, such a tether was modeled as massless and inelastic, and the results showed that a tetherballast system may be a viable method for diverting Earth-threatening asteroids from impacting the Earth. For this study, it was desired to gradually relax this assumption, so models were developed to include mass or elasticity or both. This increased model complexity comes with a price, computational time, which is also discussed. Several key issues are highlighted as the model complexity increases, such as the eect of a tether going slack on maximum tether tension.