How a nuclear bomb could save Earth from a cosmic catastrophe?

Scientists have proposed that humanity could use a nuclear bomb to deflect a large, potentially catastrophic asteroid on a collision course with Earth. This theory was explored in a recent laboratory experiment where researchers simulated a nuclear blast by directing X-rays at a marble-sized "mock asteroid."

The concept of using nuclear force against asteroids is not new. The most significant practical test of planetary defence occurred in 2022 when NASA’s DART spacecraft collided with a 160-meter-wide asteroid, successfully altering its trajectory. However, experts believe that for larger asteroids, simply crashing spacecraft into them may not suffice.

One of the most significant historical examples of an asteroid impact is the Chicxulub asteroid, which struck the Yucatan Peninsula around 66 million years ago. This event is widely believed to have caused mass extinction, including the demise of the dinosaurs. To prevent a similar fate, scientists are investigating various methods to avert future asteroid threats.

While there is no immediate danger from asteroids, ongoing research focuses on potential strategies for dealing with larger threats. One leading idea is to detonate a nuclear device, a concept popularized by the 1998 film "Armageddon," which portrayed a team of drillers saving Earth from a giant asteroid.

In a proof-of-concept study published in Nature Physics, a team of U.S. scientists examined the effectiveness of this nuclear strategy on a smaller scale. They targeted a mock asteroid measuring just 12 millimeters in diameter using the world’s largest X-ray machine at Sandia National Laboratories in Albuquerque, New Mexico. This machine can produce the brightest flash of X-rays globally, powered by 80 trillion watts of electricity.

The researchers noted that much of the energy from a nuclear explosion is released as X-rays. In space, there would be no shockwave or fireball due to the absence of air, but the X-rays would still exert significant force. In their experiments, the X-rays successfully vaporized the surface of the mock asteroid, causing the resulting vapor to propel it in the opposite direction, effectively transforming it into a rudimentary "rocket engine." The mock asteroid achieved speeds of 250 kilometers per hour, comparable to that of a high-speed train.

This experiment confirmed theoretical predictions about the effects of X-rays on asteroids for the first time, indicating that this method could be viable. Using modeling techniques, the researchers estimated that X-rays from a nuclear blast could potentially deflect an asteroid up to four kilometers wide, provided there is sufficient advance notice.

Notably, larger asteroids are generally easier to detect early, making this approach feasible even for threats similar in size to the Chicxulub asteroid. The study was based on the use of a one-megaton nuclear weapon, while the most powerful nuclear device ever tested was the Soviet Tsar Bomba, which had a yield of 50 megatons.

If such a planet-saving mission were to be executed, the nuclear device would need to be positioned several kilometers from the asteroid, but millions of kilometers away from Earth, ensuring safety and effectiveness.

However, testing this theory with an actual nuclear explosion poses significant challenges, including safety concerns, high costs, and international legal restrictions. Further research is required to address the various uncertainties involved, particularly given that asteroids can vary significantly in their composition and structure.

For instance, the asteroid impacted by DART, Dimorphos, was found to be a loosely held-together mass of rubble. The European Space Agency's Hera mission is set to launch next month to gather more information about Dimorphos's composition and how DART impacted its trajectory.

Mary Burkey, a staff scientist at Lawrence Livermore National Laboratory who was not part of the recent study, has conducted simulations on using nuclear weapons against asteroids. She commended the recent findings, stating that aligning her computational models with real-world data enhances the credibility of her results. Burkey also noted that for such a mission to be effective, there must be adequate time after a nuclear blast for the asteroid’s trajectory to be altered sufficiently to avoid collision with Earth.