The same doomsday tech designed to inflict massive harm could one day also save us. A new study suggests that nuclear bombs, specifically their powerful x-rays, could be used to deflect asteroids on a collision course with Earth. It’s a counterintuitive solution, but one that could prove invaluable in our ongoing quest for planetary defense.

A New Strategy in Planetary Defense

The idea is simple, in theory. A nuclear device detonated near an incoming asteroid would release a burst of x-rays. These high-energy particles would heat the asteroid’s surface, causing material to vaporize and expel into space. This sudden, forceful ejection would act like a rocket thruster, pushing the asteroid off its destructive path.

This concept, while seemingly outlandish, is backed by solid scientific evidence. The research team, led by Nathan Moore from Sandia National Laboratories, used an X-ray machine powerful enough to melt diamonds. They tested tiny asteroid-like objects, heating their surfaces with X-rays. The vaporized material jetted outward, pushing the objects backward like miniature rockets. As the vapor jets out, it pushes the asteroid in the opposite direction. According to computer simulations, this method could work on asteroids up to 4 kilometers wide.

“We knew right away this was a huge success,” Moore said. “This rocket-like effect is exactly what we’d want in an asteroid deflection scenario.”

The Limits of Kinetic Impacts

The new technique builds on NASA’s successful DART mission, which, in 2022, intentionally crashed a spacecraft into the asteroid Dimorphos. That mission demonstrated the power of kinetic impact to alter an asteroid’s trajectory, thereby preventing a potentially catastrophic impact. But Moore’s team found that X-rays could deflect asteroids without needing to crash anything into them.

“The consensus in the planetary defense community is that x-rays from a nuclear device would be the only option when the warning time is short,” Moore said.

But — as you might imagine — the idea of using nuclear bombs in space is controversial. A misfire could scatter radioactive material across the atmosphere, and international politics surrounding nuclear weapons make this a last-resort option. Despite the concerns, scientists agree that the method holds promise for large asteroids or when time is running out.

While NASA’s DART mission was a major milestone, kinetic impactors are only effective when an asteroid is detected early. We would need to be ready years in advance. Crashing a spacecraft into a rock can shift its orbit, but the effect is limited.

“Kinetic impactors may not be sufficient for larger asteroids, or if we have less than ten years to prepare,” said Megan Bruck Syal, a planetary defense expert at Lawrence Livermore National Laboratory.

A nuclear blast could provide more energy and momentum to deflect a massive asteroid. And the X-ray technique is less likely to break the asteroid apart into smaller fragments that could still hit Earth. This issue could arise from direct nuclear detonation. Imagine that you slightly overestimate the energy needed for deflection, and now you have thousands of radioactive fragments falling on Earth? Direct nuclear detonation looks cool in the movie Armageddon, but it’s too risky to do in the case of a genuine asteroid threat.

What’s Next?

The experiment started in a vacuum chamber, where the team suspended a mock asteroid about the size of a blueberry. This tiny object, made of quartz — a common mineral in space rocks — was hit by an intense burst from the world’s most powerful X-ray generator. In just 6.6 nanoseconds, the X-ray pulse vaporized the foil holding the quartz, sending it into free fall.

As the surface heated up and vaporized, a plume of gas erupted. This acted like a rocket thruster, pushing the quartz away from the X-ray source at around 250 kilometers per hour. Similar tests with fused silica, another common asteroid material, showed the same effect.

To assess whether this technique could actually deflect an asteroid heading toward Earth, the team fed their experimental results into computer simulations. They found that a nuclear blast emitting X-rays detonated a few kilometers from an asteroid, could deflect space rocks up to 4 kilometers wide.

While this experimental setup isn’t a perfect simulation of an asteroid deflection mission using a nuclear explosion, the scaled-down model offers a compelling way to test this technique without requiring a real-life deep-space nuclear detonation

Moore’s team is optimistic about the future. Scaling up the technique will require more tests, including experiments with different asteroid materials, such as iron and multi-mineral composites, to better simulate real space rocks.

“This is just a starting point,” Moore said. “Asteroids come in many flavors, made of different kinds of minerals.”

While testing on a real asteroid in space is still a distant goal, the success of the DART mission and Moore’s findings indicate that scientists are on the right path. Between kinetic impactors and X-ray deflection, humanity is building an arsenal of tools to protect Earth from the threat of an asteroid collision.

“It’s reassuring that large asteroids don’t impact Earth very often,” Moore told National Geographic. “But it’s even more reassuring to know we now have a way to prepare for such a disaster.”

The new findings were reported in the journal Nature Physics.