Nuclear strategies tested at Sandia could avert asteroid disaster

"To most people, the danger from asteroids seems remote," Moore said. "But our planet is hit by BB-sized asteroids every day. We call them shooting stars. We don't want to wait for a large asteroid to show up and then scramble for the right method to deflect it."

By testing synthetic asteroid materials at the Z machine, researchers are compiling data to help future responders predict the best methods for deflecting real asteroids before they reach Earth.

Preparing for the unexpected
Moore highlighted the lack of large observable asteroids near Earth, which limits opportunities for preemptive deflection experiments. "The day after, there would be no re-dos," Moore said.

The need for preparation was emphasized by the National Academy of Sciences in 2023 when it labeled planetary defense a national priority. NASA estimates that around 25,000 objects large enough to cause damage could approach Earth, but only about a third have been tracked. Some are hidden by the sun's glare, and a small asteroid in 2013 created significant damage in Russia. The largest asteroid impacts, like the one that wiped out the dinosaurs, can have even more devastating effects.

X-ray 'scissors' simulate deflection in space
To address this threat, Moore's team developed a technique using X-ray pulses from the Z machine to model how nuclear explosions might change the momentum of asteroids in space. By removing friction and gravity in their experiments with a method called X-ray scissors, the team can replicate the conditions of a free-floating asteroid impacted by nuclear forces.

"I started working through the logic of how I could deflect a miniature asteroid in a laboratory just like in outer space," Moore said. This process allows for testing how asteroid material would respond to redirection attempts without the interference of Earth's gravity or mechanical friction.

In their experiments, a tiny piece of silica-a material similar to asteroid composition-was placed inside the Z machine's target chamber. The material was suspended by an ultra-thin foil that vaporized when Z fired, leaving the material to float in a vacuum. The resulting data gave researchers insight into how asteroids might react to deflection forces in space.

Building a guide for future asteroid deflection
The experiments are part of a broader effort to create a reference library of asteroid deflection responses. Future asteroid missions could use this data to determine the best strategy for deflecting an approaching asteroid, based on its mass, velocity, and composition.

"Some asteroids are believed to be held together loosely-so-called 'rubble piles'-and how that would respond in the explosion will require more complicated mathematics," Moore said. Practice missions in space are rare and expensive, making the data gathered by Sandia's experiments even more valuable.

NASA has conducted one asteroid deflection mission using kinetic impact, a technique that is less effective for the most dangerous types of asteroids.

In addition to its planetary defense implications, this research could deepen understanding of asteroid composition and even inform the development of materials for future fusion reactors.

Research Report:Simulation of asteroid deflection with a megajoule-class X-ray pulse