Three-Dimensional Simulations Reveal Critical Role of Impactor Shape in Kinetic Impact for Asteroid Defense

With the increasing number of confirmed near-Earth asteroids, their potential threat to Earth’s safety grows. Kinetic impact remains the most mature asteroid defense technique. To address the prevalent use of 2-dimensional models and spherical impactors in existing kinetic impact simulation researches, based on LS-DYNA software and secondary development of material models, a 3-dimensional kinetic impact simulation model was established in the context of verification with Double Asteroid Redirection Test impact. The effectiveness of the material model and geometric modeling methods was verified through momentum transfer coefficients. Three-dimensional smooth particle hydrodynamic models for 6 shapes of impactors, including sphere, cube, and cuboid, were established. It was found that the momentum transfer coefficients caused by impactors of different shapes vary by up to 29.4%. The main factor affecting momentum transfer coefficient is the aspect ratio in the envelope size of the impactor. Within the aspect ratio range of 0.35 to 2.83, momentum transfer coefficient increases with aspect ratio. However, as aspect ratio continues to increase further, β diminishes accordingly. The difference in the transverse cross-sectional shape of the impactor under the same aspect ratio only affects the shape of crater in the early excavation stage. The flat cuboid impactor produces an elliptical crater, with a maximum difference of 38% in the long and short axes, but this difference diminishes as the crater expands.