The impact of near-Earth asteroids (NEAs) poses a major potential hazard to humanity. Among the various planetary-defense strategies, the kinetic impact method is currently regarded as the most practical approach due to its demonstrated effectiveness and relatively mature technological readiness. In 2022, the United States carried out the on-orbit Double Asteroid Redirection Test (DART), successfully altering the orbital period of the secondary component in a binary asteroid system, marking a significant milestone in planetary defense. However, most NEAs are single bodies on the scale of several tens of meters. These small asteroids have a higher impact frequency and, if they impact Earth, are capable of causing city-level damage, thus representing a more immediate and realistic threat to human society. In this study, we propose an on-orbit test mission concept for kinetic impact-based mitigation targeting small, single NEAs. The proposed mission architecture is derived from analyses of mission requirements, mission system-level design, target-selection criteria, trajectory-optimization strategies, and post-impact deflection simulations. First, four mission design principles are formulated through a systematic review of the mission requirements. Second, an overall mission concept is developed involving a dual-spacecraft launch profile, in which a precursor observer spacecraft performs early rendezvous and characterization of the target, followed by a dedicated impactor spacecraft that subsequently executes the high-velocity collision. Based on the design principles, we establish a set of target-selection criteria that consider the asteroid’s physical properties, orbital characteristics, observability conditions, and safety. To address the constraints associated with simultaneous launch, sequential arrival, and the differing relative velocities required for rendezvous and impact, we analyze feasible mission windows and propose a trajectory strategy that employs Earth-elliptical phasing orbits for initial transfer in Earth-moon space and a Venus gravity-assist maneuver for deep-space transfer. This approach effectively decouples the transfer trajectories of the observer and impactor, ensuring that both spacecraft meet their respective timing and dynamical constraints. We further conduct detailed simulations of the mitigation performance by considering different asteroid material properties and different impact angles. The simulations yield corresponding impact-response outcomes and allow us to evaluate the deflection distance and the medium-to-long-term evolution of the post-impact trajectory under various parameters. Coupled dynamical analyses indicate that the proposed kinetic-impactor mission concept can induce a meaningful orbital change—or potentially structural disruption—for a monolithic NEA with a diameter of approximately 30 meters, thereby demonstrating the feasibility of validating kinetic-impact mitigation strategies for small NEAs. The mission concept and associated analytical results presented in this paper provide a valuable reference for the design and implementation of future on-orbit test missions aimed at enhancing planetary-defense capabilities.
Wu et al. (Thu,) studied this question.