Targets selection and mission optimization of kinetic impact deflection test mission for small size asteroids

Abstract

Near-Earth Asteroids (NEAs) impact poses a major potential threat to life on Earth, and kinetic impact is currently the most mature and feasible means of asteroid defense. The deflection effect of kinetic impact (KI) is closely related to the asteroid orbit, structure, material composition, mechanical properties, impact velocity, and other factors. To ensure the success of an asteroid defense mission, it is crucial to conduct in-orbit test missions and gain a thorough understanding of momentum transfer and orbital deflection principles. The Double Asteroid Redirection Test (DART) Mission has been launched and successfully impacted the Dimorphos whose diameter is 160 m. However, missions specifically targeting near-Earth asteroids with diameters ranging from 20 m to 90 m, which are more abundant but fainter and pose greater challenges in terms of navigation and guidance accuracy, have not been executed. For in-orbit demonstration and performance evaluation of kinetic impact asteroid deflection missions, the selection criteria for candidate asteroids were first established considering the size, orbit distribution, orbit uncertainty, characteristic information, and optical observability. 20 near-Earth asteroids were selected as primary candidate asteroids from the 28,946 cataloged near-Earth asteroids. Then, according to the mission cost and the way to evaluate the deflection distance, two Kinetic Impact in-orbit Demonstration (KID) mission scenarios were designed. A kinetic impact test mission optimization model was developed, integrating global and local optimization algorithms, while considering constraints like launch vehicle, launch site, and observability during and after impact. The model utilized a high-precision orbital dynamics model of the solar system to assess the deflection effect on the asteroid. We further reduced the candidate asteroids to 7 and ranked them in each mission scenario. Additionally, disruption conditions of the asteroids were examined, and mission parameters were re-optimized to ensure deflection without disruption. Accounting for factors such as the momentum enhancement factor, the impact probability between the asteroid and Earth was calculated for a 200-year period following the impact, thus evaluating the risk of an asteroid colliding with Earth after the KID mission implementation. The research can provide references for the target selection and kinetic impact test mission options for 20–90 m asteroids.