Recent computer simulations suggest that the plot of the 1998 science fiction film Armageddon, which proposed nuking an asteroid to prevent an Earth impact, might hold a key to planetary defense. Chinese researchers have found that detonating a nuclear bomb deep within an asteroid is not only feasible but could be the most effective method for averting an apocalyptic collision.
While the Hollywood portrayal featured human astronauts, this strategy would be executed by uncrewed spacecraft. The simulations indicate that a 164-foot (50-meter) asteroid could be entirely shattered by a 300-kiloton nuclear bomb, approximately 20 times the yield of the bomb dropped on Hiroshima. For a larger, 328-foot (100-meter) asteroid, a three-megaton bomb—200 times the size of the Hiroshima device—could break it into manageable pieces. Even a one-kilometer wide "city killer" asteroid could potentially be nudged off its collision course with a precisely placed explosion of this magnitude.
While no immediate threats are currently known, scientists are concerned about the potential for a future impact. Since asteroid tracking began in the 1990s, over 40,000 near-Earth objects have been logged. The Planetary Society estimates that 266 of these are large enough to devastate a city and may pass closer to Earth than the Moon.
Previous theories explored using nuclear explosions to deflect or destroy asteroids, but a major challenge has been the loss of energy into space. The proposed two-stage process aims to overcome this. First, a "penetrator" spacecraft would be deliberately crashed into the asteroid at high speed to create a crater. A second spacecraft would then deposit a nuclear warhead into this crater for detonation. This method offers advantages over a direct impact with a nuclear device, allowing for precise placement of the explosion and avoiding the need for a nuclear weapon to survive a high-speed impact.
The primary benefit, researchers state, is significantly amplifying the force with which the blast pushes the asteroid. Detonating a three-megaton bomb 20 meters (65 feet) beneath the surface of a one-kilometer asteroid could alter its velocity by more than 0.67 miles per hour. This level of deflection, though seemingly small, is substantial enough over vast distances to alter an asteroid's trajectory and avert an Earth impact.
This approach contrasts with NASA's Double Asteroid Redirection Test (DART) mission in 2022, which used a kinetic impactor to change the speed of the 160-meter asteroid Dimorphos by 2.7 millimeters per second. The simulated buried nuclear explosion's effect is estimated to be over 110 times greater than the DART mission's achieved deflection. A larger deflection significantly reduces the required warning time to alter an asteroid's path. A change of 2.2 miles per hour could allow for a deflection with as little as 60 days' notice, while a smaller change would necessitate years of advance warning.
For scenarios with limited time, the two-stage nuclear detonation method is presented as the only practical solution. The researchers' findings, published in the journal Space: Science & Technology, provide a theoretical basis for developing defense strategies against large or short-warning-time asteroid threats, enhancing humanity's capability to respond to such impacts.