An asteroid large enough to destroy a city could pose a serious threat if discovered on a collision course with Earth. A new scientific simulation suggests that a nuclear device detonated near such an object might disrupt it—even without touching its surface.
Researchers led by astrophysicist Isaiah Santistevan of Lawrence Livermore National Laboratory modeled the effects of a 1-megaton nuclear explosion on a porous asteroid measuring 160 meters, or about 525 feet, across.
The results indicate that the approach could be a viable emergency option in certain planetary-defense scenarios.
“Based on the extent of damage, the directionality of the material motion, and the [velocity change] that we impart on these asteroids, we suggest that disruption is highly likely for two of the three scenarios,” the researchers write in a paper in The Planetary Science Journal.
“Simulations such as these help to further inform the viability of nuclear mitigation options for planetary defense and support emergency response planning.”
Why Large Asteroids Are Difficult to Stop
Even an asteroid roughly the size of a football field could devastate a major metropolitan area. Detecting these objects can also be challenging because some have extremely dark, nonreflective surfaces that absorb much of the sunlight reaching them.
Scientists have studied several possible methods for preventing a collision. One option is to alter an asteroid’s speed slightly, causing it to miss Earth. NASA demonstrated this concept in 2022 when its Double Asteroid Redirection Test spacecraft intentionally struck the small asteroid moonlet Dimorphos.
However, a conventional deflection mission requires sufficient warning. If a dangerous asteroid were discovered too late—or proved too large—a more powerful intervention might be necessary.
Nuclear mitigation has long been proposed, but the popular image of landing a warhead on an asteroid and blowing it apart creates major engineering problems. Asteroids can rotate or tumble unpredictably, making it difficult for a spacecraft to land, remain stable and drill beneath the surface.
The new simulations show that landing may not be required.
X-Rays, Not a Shockwave, Would Deliver the Force
Radiation could vaporize the asteroid’s surface
Because space is nearly a vacuum, it cannot carry a conventional atmospheric shockwave from a nuclear explosion. Instead, researchers found that X-rays produced by the detonation could transfer enormous amounts of energy directly into the asteroid.
An estimated 70% to 80% of the energy released by a nuclear device can emerge as X-rays. Those X-rays would strike a thin layer of the asteroid’s surface, heating and vaporizing its material.
“These X-rays deposit energy in a thin surface layer of the asteroid, driving vaporization and ablation,” the researchers explain.
“The vaporized material expands, and if it can overcome the local gravitational field, it is ejected, which imparts a change in momentum that alters the asteroid’s velocity.”
The process resembles the way material escaping from a comet can influence the comet’s movement and rotation. As heated asteroid material shoots into space, the reaction force could change the object’s trajectory.
Internal fractures could break the asteroid apart
The sudden X-ray heating could also generate a powerful shock wave inside the asteroid itself. That internal stress could crack and fracture the object, potentially causing widespread disruption rather than merely changing its course.
To examine the effect, the researchers created three detailed three-dimensional simulations. Their virtual asteroid was based on the shape and porous structure of Bennu, the near-Earth asteroid visited by NASA’s OSIRIS-REx spacecraft.
The team adjusted factors including the detonation distance and the asteroid’s resistance to fracturing. Its fracture models were informed by two actual space rocks: the Chelyabinsk meteor, which exploded over Russia in 2013, and the Aba Panu meteorite, which fell in Nigeria in 2018.
Nearby Detonation Caused Extensive Damage
In the longest simulation, the nuclear device was detonated about 10 meters, or nearly 33 feet, above the asteroid’s surface. The model showed that 98.2% of the asteroid’s material became fully damaged.
About 97% of the material was moving faster than the asteroid’s escape velocity, meaning much of it could disperse rather than immediately fall back together. Large sections also moved sideways in opposing directions, suggesting the asteroid was effectively pulling itself apart.
The researchers also modeled a detonation from 25 meters, or about 82 feet, away to study how distance affected the transfer of radiation and the resulting fracture pattern.
Nuclear Mitigation Remains an Emergency Option
The findings do not mean nuclear devices are ready for immediate use against asteroids. Any real mission would require extensive planning, accurate tracking and a careful assessment of whether fragmentation could create additional hazards for Earth.
Still, the simulations provide evidence that an off-surface nuclear detonation could disrupt a threatening asteroid under some conditions. For planetary-defense officials facing a large object with limited warning, the research may help clarify one of humanity’s most powerful—but complex—emergency options.
Chris Skeldon is a contributor to Brytfmonline.com, covering a wide range of topics including news, politics, business, technology, sports, entertainment, and lifestyle. He focuses on delivering clear, accurate, and reader-friendly reporting that helps audiences stay informed about current events and emerging developments. With an emphasis on useful information and balanced storytelling, Chris aims to provide timely coverage of issues and stories that matter most to readers.