Researchers in the United States are developing three-dimensional simulations to study how a nuclear device could be used to deflect or potentially disrupt an Earth-threatening asteroid.
The team from Lawrence Livermore National Laboratory (LLNL) uses Spheral simulation code to more accurately model how an asteroid might respond if X-rays from a nuclear device exploding near its surface rapidly heat and vaporize material. After validating the approach against established asteroid deflection models, the researchers used Spheral to examine three complex disruption scenarios.
A dangerous asteroid impact could potentially be prevented
The team found that, unlike many natural disasters, a dangerous asteroid impact could potentially be prevented if the object was detected early enough. One approach is deflection – a small change in speed that causes the asteroid to miss Earth but remain largely intact. Another approach is disruption, in which an asteroid is intentionally fragmented and scattered so that no remaining piece poses a significant threat to the planet.
NASA’s Double Asteroid Redirection Test (DART) demonstrated a kinetic impact approach to deflection in 2022 by intentionally striking the asteroid moon Dimorphos. According to a press release, 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.
Two of the simulations showed clear signs of disruption, illustrating how high-precision 3D modeling can help researchers better understand how an asteroid might respond to a nuclear containment attempt, the press release said.
“These simulations give us a much more detailed picture of how an asteroid might respond to a nuclear containment attempt,” said Isaiah Santistevan, who led the study. “The ability to model damage, fractures and material movement in three dimensions is an important step in improving our ability to evaluate options for defending the planet.”
1,500 one-dimensional spherical simulations with asteroid deflection results
To test the approach, the researchers said 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 perturbation simulations. Santistevan showed that Spheral is particularly well suited to modeling problems related to material damage, fractures and fragmentation.
The researchers then modeled three disruption scenarios involving an irregularly shaped asteroid about 160 meters in diameter, varying both the distance of the hypothetical nuclear detonation and assumptions about how easily the asteroid material would break.
In the longest-running simulation, about 98% of the asteroid material was completely damaged, meaning it had significantly lost its ability to remain intact. The simulation also showed that about 97% was moving faster than the asteroid’s escape velocity, with most of the material moving in opposite directions, further indicating that the body was breaking apart.
“What’s encouraging is that we see the asteroid sustaining significant damage while at the same time the material is moving fast enough to escape its gravitational pull,” Santistevan said. “These are important indicators that the asteroid is in the process of destroying itself, and the 3D simulations allow us to study this process in much more detail.”
