For decades, both scientists and Hollywood movie producers have speculated about using nuclear bombs to prevent a catastrophic asteroid impact. While the concept has often seemed the stuff of science fiction, researchers at Sandia National Laboratories in the U.S. have made this idea more plausible, showcasing how a nuclear explosion might save Earth from a doomsday scenario.
Nuclear Option for Planetary Defense
Physicists at Sandia National Laboratories have taken a significant step towards nuclear-assisted planetary defense, putting the theory to the test in a landmark experiment. Using their powerful Z Machine, they demonstrated how a nuclear blast could vaporize part of an asteroid’s surface, creating a violent reaction that could deflect it from its Earth-bound trajectory. The intense pulse of radiation from the explosion, simulated in the lab using X-rays, heats the asteroid’s surface to tens of thousands of degrees. The resulting ball of gas expands rapidly, nudging the asteroid in the opposite direction—a reaction similar to a rocket.
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“The vaporized material shoots off one side, pushing the asteroid in the opposite direction,” explained Dr. Nathan Moore, the lead author of the study. “It’s like turning the asteroid into its own rocket.”
Why Do We Need to Prepare?
While asteroid impacts of devastating magnitude are rare, history provides stark reminders of their destructive potential. The most infamous example is the asteroid that wiped out the dinosaurs 66 million years ago, estimated to have been six miles wide. However, smaller asteroids can still pose a severe threat. The 2013 Chelyabinsk meteor, which was only about 60 feet wide, exploded over Russia, injuring more than 1,200 people and damaging buildings across 200 square miles.
Given the existential threat that asteroids pose, scientists have been exploring various defense strategies. In 2022, NASA’s DART mission proved that a kinetic impactor could deflect an asteroid when it intentionally crashed into Dimorphos, a moonlet of the asteroid Didymos. However, this approach only works with smaller space rocks and when there’s a long lead time before impact.
The nuclear option, meanwhile, is reserved for larger asteroids or scenarios where time is short. Unlike Hollywood’s depiction in films like Armageddon, the goal is not to drill into the asteroid and blow it apart. Instead, the preferred method is a “standoff explosion,” where a nuclear blast vaporizes part of the asteroid’s surface, pushing the rest off-course through Newton’s third law of motion.
Science Behind the Plan
Moore’s team conducted an unprecedented experiment where they exposed synthetic asteroid materials to intense X-ray pulses, simulating the effects of a nuclear explosion. In the study published in Nature Physics, they found that the material was vaporized so quickly that the synthetic asteroid pieces flew backwards at speeds of nearly 200 miles per hour. Their findings suggest that this strategy could deflect asteroids up to 2.5 miles wide, though with enough warning, it might work on larger asteroids as well.
Other scientists, such as Colin Snodgrass from the DART mission science team, acknowledge that understanding how these results scale up to real-life asteroids is crucial. Yet, the experiment is seen as a major breakthrough in planetary defense.
Caution Before Detonation
While promising, using nuclear weapons in space is fraught with risks. The greatest concern is breaking an asteroid into smaller, equally deadly fragments that could still hit Earth. However, as Moore points out, in a short-notice situation, the nuclear option may be our best chance of survival.
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“Even though large asteroid impacts are rare, the potential catastrophe is enormous,” said Moore. “We now have a way to prepare for that form of natural disaster.”