Nuking an asteroid on short notice could be our last line of defense against a potential catastrophic impact. While it's a drastic measure, the threat posed by Near-Earth Asteroids (NEAs) is very real. As of July 2024, over 10,000 NEAs with diameters larger than 140 meters have been discovered, and the number of undiscovered NEAs could blindside us with little warning time. This is why it's crucial to develop strategies to detect and deflect these asteroids before they become a global disaster.
The China Academy of Launch Vehicle Technology's recent paper explores two potential scenarios for nuclear asteroid deflection. The first scenario involves a quick and dirty approach: flying a nuclear weapon into the side of an asteroid and detonating it with precise timing. While this method is fast, it presents significant challenges. Selecting an ideal impact site is impractical, and the coupling energy transferred to the asteroid might be weak. Additionally, the nuclear warhead must survive high-speed debris impact and detonate with microsecond precision, which are major engineering hurdles.
The second scenario builds upon the success of the Double Asteroid Redirection Test (DART) mission. This method uses a conventional penetration device, such as a tandem impactor, to pre-excavate a deep crater in the asteroid. After the crater is created, a nuclear device is inserted into the pit to initiate detonation. Simulations show that this technique significantly increases the energy transferred to the asteroid, allowing for a more substantial change in its orbital path.
However, there are concerns about the current simulations. The authors modeled the asteroids as solid basalt, but hazardous asteroids are more likely to be rubble piles. It's uncertain if the simulation would hold true for the more chaotic and likely scenario of a rubble pile asteroid. Additionally, the second scenario is incredibly challenging to execute, requiring precise orbital matching, site reconnaissance, and consecutive kinetic impacts, all while navigating the debris created by the impactors.
Finding and deflecting asteroids is a complex task. The NEO Surveyor mission, scheduled for launch in 2027, aims to detect near-Earth asteroids. If a threatening asteroid is discovered, we must be prepared with effective deflection strategies. While nuclear weapons offer a powerful solution, they also raise ethical and safety concerns. The paper highlights the need for further research and development to ensure our ability to protect Earth from asteroid impacts.
