Assessing the Feasibility of Ion Beam-Based Asteroid Deflection for Planetary Defense

The potential threat of asteroid impacts on Earth has prompted significant research into methods for asteroid deflection such as kinetic impactor, gravity tractor, nuclear options and ion beam deflection (iBeam). Among these methods, iBeam is a promising technique as it can achieve significant deflection without the risk of unintended asteroid disruption. In this paper, we analyze the feasibility of iBeam missions for deflecting potentially hazardous asteroids. We first present the architecture for iBeam missions, including the design of the spacecraft and subsystem models, multiple ion-beam plasma plume models, and a dynamics model for the spacecraft-asteroid system. Utilizing these models, we implement closed-loop control for maintaining iBeam spacecraft position relative to the asteroid with a proportional-integralderivative controller and manage attitude using a nonlinear proportional-derivative controller. We then perform Monte Carlo (MC) simulations of complete iBeam missions over various asteroid characteristics to study iBeam efficiency. Through the MC simulations, we study the effect of asteroid diameter (50-100 m), density (2-8 g cm-3), spin axis (principal axis vs minor axis), and shape (spherical vs irregular) on the deflection. Results indicate that under the assumed capabilities of the iBeam spacecraft, successful deflection of 50 m diameter spherical asteroids is achievable within 6 months for densities under 4 g/cm3 or within 5 years for densities below 8 g/cm3. Similarly, for 150 m diameter spherical asteroids, successful deflection within 5 years is possible if densities are under 2 g/cm3. Additionally, the study reveals a marginal influence of spin axis and shape on deflection. Compared to a reference case of a spherical asteroid, a maximum change of 5.6% is observed for irregular-shaped asteroids rotating around their minimum moment of inertia axis pointed towards the spacecraft.