Researchers in the United States are developing three-dimensional simulations to examine how a nuclear device could be used to deflect or potentially disrupt an asteroid threatening Earth.
The team from Lawrence Livermore National Laboratory (LLNL) uses Spheral simulation code to more accurately model how an asteroid might respond when X-rays from a nuclear device detonated near its surface rapidly heat and vaporize material. After validating the approach against established asteroid-deflection models, researchers used Spheral to study three complex disruption scenarios.
Hazardous asteroid impact could potentially be prevented
The team revealed that unlike many natural disasters, a hazardous asteroid impact could potentially be prevented if the object is detected early enough. One approach is deflection — imparting a small change in velocity that causes the asteroid to miss Earth while largely remaining intact. Another approach is disruption, in which an asteroid is intentionally fragmented and dispersed so that no remaining piece poses a significant threat to the planet.
NASA’s Double Asteroid Redirection Test, or DART, demonstrated a kinetic-impact approach to deflection in 2022 by deliberately striking the asteroid moon Dimorphos. Nuclear mitigation represents an alternative emergency option, particularly for larger objects or scenarios with shorter warning times, because much more energy can be delivered to an asteroid than the kinetic energy of a spacecraft impactor, according to a press release.
Two of the simulations showed strong signs of disruption, highlighting how high-fidelity 3D modeling can help researchers better understand how an asteroid could respond to a nuclear mitigation attempt, as per the release.
“These simulations give us a much more detailed picture of how an asteroid may respond to a nuclear mitigation attempt,” said Isaiah Santistevan, who led the study. “Being able to model damage, fracture and material motion in three dimensions is an important step toward improving our ability to evaluate planetary defense options.”
1,500 one-dimensional Spheral simulations with asteroid deflection results
Researchers revealed that to test the approach, they compared more than 1,500 one-dimensional Spheral simulations with asteroid deflection results from LLNL’s established Ares simulation code.
The calculations showed close agreement between the two codes, giving researchers confidence to use Spheral for more complex 3D disruption simulations. Santistevan revealed that spheral is particularly well-suited to modeling problems involving material damage, fracture and fragmentation.
The researchers then modeled three disruption scenarios involving an irregularly shaped asteroid roughly 160 meters across, varying both the distance of the hypothetical nuclear detonation and assumptions about how easily the asteroid material would fracture.
In the longest-running simulation, about 98% of the asteroid material became fully damaged, meaning it had severely lost its ability to remain intact. The simulation also showed that roughly 97% was moving faster than the asteroid’s escape velocity, with the majority of material moving in opposite directions, further indicating that the body was breaking apart.
“What’s encouraging is that we’re seeing the asteroid sustain extensive damage while material is also moving fast enough to escape its gravitational pull,” Santistevan said. “Those are important indicators that the asteroid is in the process of disrupting, and the 3D simulations allow us to examine that process in much greater detail.”