Asteroids hold invaluable scientific information and provide critical insights into the origins and evolution of the solar system, highlighting the significance of asteroid sample-return missions. Given that asteroid surfaces are highly likely to be covered with rocks, samplers must possess efficient rock-breaking capabilities while generating low reaction forces. To address this requirement, five distinct types of kinetic energy rock-breaking projectiles were designed. Simulation analyses revealed that the "petal-shaped" rock-breaking projectile undergoes sufficient plastic deformation, expands the lateral rock-breaking area, and enables effective surface cratering and rock-breaking. Comparative experiments, conducted under varying conditions of projectile material, projectile mass, and incident velocity, demonstrated that the optimal rock-breaking performance is achieved when the projectile adopts a non-penetrating petal structure, uses pure tantalum as the material, and operates at an incident velocity ranging from 400 to 600 m/s. The findings of this study provide an efficient rock-breaking solution under weak gravity conditions for asteroid sampling missions and lay a technical foundation for sampling tasks on other extraterrestrial bodies, such as the Moon and Mars.