Low-Energy Near-Earth Asteroid Capture Using Momentum Exchange Strategies

Abstract

This paper investigates the concept of capturing small near-Earth asteroids into bound periodic orbits at the Sun–Earth and points using momentum exchange. A small asteroid is first maneuvered to engineer a fly-by with a larger asteroid. Two strategies are then considered: when the small asteroid approaches the vicinity of the large asteroid, it will either impact the large asteroid or connect to it with a tether. In both strategies, momentum exchange can be used to effect the capture of one of the asteroids. Then, a two-impulse Lambert arc is used to design a postencounter transfer trajectory to the stable manifolds of the Sun–Earth or points. A selection strategy for candidate asteroids is proposed by considering both the deflection windows for capturing asteroids and the size of the asteroids. By investigating the outcome of the impact on the small asteroid, or the tension of the tether, the maximum velocity increment available using these momentum exchange strategies is investigated. Finally, a detailed design procedure is presented, which is then optimized using a global optimization strategy. The results show that, in principle, capture strategies using momentum exchange have the potential to deliver low-energy capture of asteroids although significant practical challenges remain.