Sandia National Laboratories scientists have created the most accurate simulation of an asteroid-deflection scenario using X-rays generated by a nuclear blast, revealing that a space rock’s shape and the detonation location can dramatically alter the method’s effectiveness.
Although more development is expected to improve the model’s accuracy, the research team behind its creation said their updated approach removes much of the guesswork in a doomsday scenario, increasing the chances of successfully deflecting a dangerous asteroid.
Deflecting a Dangerous Incoming Asteroid with a Nuclear Blast Isn’t Science Fiction
In science fiction, humans often use nuclear missiles to redirect dangerous asteroids headed toward Earth, with varying levels of success. Although no real-life scenario has required an actual nuclear missile to deflect an asteroid, scientists have built models of the event to plan for the worst case.
Instead of blasting the target into millions of pieces, Sandia National Laboratories scientists explored using X-rays emitted from a nuclear blast to “nudge” a dangerous asteroid off course. According to Sandia physicist Nathan Moore, the idea first came to him when the facility’s Z machine deflected a small piece of an asteroid with X-rays.
“I started wondering how to scale up the calculation to more accurately predict deflection of a full-scale asteroid,” Moore explained.
When investigating the problem, Moore found that most existing X-ray asteroid deflection models had taken a mathematical shortcut. More specifically, most abandoned the complex, calculation-intensive mathematics of naturally shaped asteroids in favor of hypothetical spherical ones. However, as the SNL research team leader noted, “the trouble is, spherical asteroids don’t exist,” adding that asteroids “come in all kinds of odd, lumpy shapes.”
While searching for a new approach that accounts for the unusual shapes of space rocks and the complex mathematics of X-ray deflection, Moore said he “latched onto some work one of my colleagues was doing” on outgassing in objects like asteroids moving through space, which led to an “aha moment.”
“We realized we could do this,” Moore said. “No more spheres. We would be able to model deflection for any asteroid.”
Researchers Surprised by How Much Aim Affected Success
To build the model, Moore said he borrowed high-fidelity codes used at Sandia for different types of problems and combined their specific abilities into one asteroid deflection tool. This included the ALLEGRA code, which Moore noted is typically used to model “fast, high-energy experiments, like magnetically imploding wires on the Z machine.”
The team also included SPARTA. Moore said this is a direct simulation Monte Carlo code normally used to “model comparatively weak, slowly evolving forces, like the drag on a satellite from the solar wind.”
“Our new algorithm is over 1,600 times faster, which was critical to this breakthrough,” Moore said. “With the old models, computers just couldn’t handle it.”
Using the new approach, the team modeled a simulated asteroid using high-resolution 3D imagery from spacecraft flybys of actual asteroids. Next, the Sandia team blasted their simulated asteroid with simulated X-rays to measure the effect. To approximate real-world scenarios, the team adjusted the explosion’s size and distance and changed which side of the rock was irradiated.
After comparing the results, Moore and colleagues found that irradiating different sides of a naturally shaped asteroid altered how much momentum the blast transferred to the asteroid. They also found that altering the blast’s location affected how much spin was induced in the target rock.
In some cases, the team observed a fivefold difference in rotational speed between two different blast locations. In another case, the team found that the asteroid’s change in rotational velocity after explosion “varied by a factor of 17.”
“We expected aim to matter,” Moore said. “What surprised us was how much.”
“Guess Wrong, and it Could be a Bad Day”
When discussing the current model’s limitations, the Sandi team noted that their model requires “fairly accurate” asteroid shape data from all sides. In a real-world scenario, there may not be enough time to send a spacecraft to capture such data. Moore also pointed to limitations in predicting how an asteroid will react after it is broken into several pieces.
“We can’t predict breakup of the entire asteroid body accurately yet,” Moore said, adding that the current version only models the breakup of surface material.
Still, the study author noted, the model reduces much of the guesswork in avoiding a doomsday scenario, with targeting the blast location becoming increasingly critical to success.
“Our study shows how important it is to aim carefully,” Moore said. “Pick the right side, and you win. Guess wrong, and it could be a bad day.”
Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.