PLANETARY DEFENSEDefense Technology for Large-Sized Near-Earth Asteroids

Near‑Earth asteroid impacts pose a major threat that could lead to the destruction of human civilization, having already caused catastrophic environmental changes and mass extinctions multiple times in history. In recent years, asteroids with diameters ranging from tens to hundreds of meters have frequently made close flybys of Earth, and a large number of large‑sized asteroids remain undiscovered, with warning times often only a few days to weeks. For large‑sized asteroids exceeding 100 meters in diameter, or even kilometer‑scale ones, traditional kinetic impact or long‑term force deflection methods offer limited energy and cannot achieve effective deflection within short timeframes. Using the enormous energy generated by nuclear detonation to directly destroy or rapidly deflect the asteroid’s orbit is the most effective, and in extreme cases the only feasible, approach for dealing with large asteroids or those with short warning times. However, existing research on detonation defense has mostly focused on the direct rendezvous impact mode, in which the impact and detonation positions cannot be autonomously selected and energy coupling is relatively weak. Moreover, there is a lack of systematic analysis of the capability coverage and overall effectiveness of different defense modes, severely constraining the optimization of engineering designs.

In a recent study published in Space: Science & Technology, the team led by Researcher Wang Xiaowei from the China Academy of Launch Vehicle Technology proposed a novel approach to detonation defense technology for large‑sized near‑Earth asteroids. Building on the energy advantages of nuclear detonation, the study proposed two defense modes: a direct rendezvous impact detonation mode and a novel flyby pre‑excavation detonation mode. By establishing a virtual threat asteroid database and using the finite element method‑smoothed particle hydrodynamics adaptive method to simulate damage effects under various yields and burial depths, the study systematically analyzed the influence of key factors, including launch vehicle characteristic energy (C3), impact velocity, and velocity increment provided by the space transfer platform, on defense coverage and deflection effectiveness. The results demonstrate that the flyby pre-excavation detonation mode, due to its ability to autonomously select the cratering location and achieve deep detonation, offers stronger energy coupling.