Which Side of an Asteroid a Nuclear Burst Hits Could Change Its Deflection Nearly Fivefold, Sandia Study Finds

A nuclear X-ray burst aimed at an asteroid could change its speed nearly five times more depending on which side it strikes, Sandia National Laboratories simulations found. The study was published in the journal Icarus and described in a Sandia release dated Nov. 3. The work involved simulations only.

Related: ESA’s Hera Sees Dimorphos for the First Time, Four Years After NASA’s DART Impact.

What the simulations found

In one simulated case, the asteroid’s speed changed by 3.9 millimeters per second when irradiated from one direction, the release said. The change was 0.8 millimeters per second from another direction. For a different simulated asteroid, the change in spin varied by a factor of 17 depending on the X-rays’ direction.

“We expected aim to matter,” said Nathan Moore, the Sandia physicist who led the research. “What surprised us was how much.”

The authors modeled three bodies with different shapes, the asteroids Bennu, Itokawa and Golevka, Universe Today reported. A body’s orientation could raise deflection velocity by up to nearly twofold for Bennu, fourfold for Itokawa and fivefold for Golevka, the authors wrote, according to Universe Today.

Why shape matters

Earlier models typically forced researchers to choose between representing an asteroid’s complex shape and calculating the physics in detail, the release said. Simpler approaches overlook the irregular shapes of real asteroids, which can have ridges, depressions and uneven surfaces, according to the release.

“You can make estimates that way, but asteroids come in all kinds of odd, lumpy shapes,” Moore said.

The team combined two Sandia simulation codes, the release said. ALEGRA is normally used to model fast, high-energy experiments, and SPARTA is usually used for weak, slowly evolving forces such as drag on a satellite. Moore said the new algorithm is more than 1,600 times faster than the older models.

How the model works

The model reconstructs an asteroid from detailed 3D images captured during spacecraft flybys, according to the release. It then simulates an X-ray burst while researchers adjust the explosion’s strength, its distance and the direction of the radiation. The software estimates how much material would vaporize across the surface, the push that results and the change in rotation.

The vaporized material creates most of the deflection thrust, Universe Today reported.

What the study does not show

“We can’t predict breakup of the entire asteroid body accurately yet,” Moore said. The model considers only the breakup of rocks on the surface, he said. A deflection mission would ideally change an asteroid’s path without breaking it into several dangerous fragments, according to the release.

Moore’s work grew out of an earlier experiment on Sandia’s Z machine, the release said. That experiment was the first demonstration that X-rays could deflect a small piece of asteroid material. The research was funded through Sandia’s Laboratory Directed Research and Development program, according to the release.

For more coverage, see Science and Technology.

Sources

• Sandia National Laboratories (via EurekAlert): Asteroid defense hits a lump in the road
• ScienceDaily (Sandia release): A nuclear blast could save Earth from an asteroid, but there’s a catch
• Universe Today: Asteroids’ oddball shapes make deflecting them challenging

About the reporter: Theo Lin is an AI reporter covering AI, technology and science for The Boston Report. This article was produced with AI under our editorial policy. Read our AI and media disclosure.