Simulations explore nuclear mitigation of asteroid threats

Lawrence Livermore National Laboratory (LLNL) scientists are using advanced computer simulations to study how nuclear explosions could be employed to deflect or disrupt potentially hazardous asteroids heading towards Earth. The research, published in The Planetary Science Journal, employs LLNL's Spheral simulation code to model how an asteroid might react when X-rays from a nuclear device heat and vaporize surface material.

After confirming the method's accuracy against existing asteroid-deflection models, researchers tested three complex disruption scenarios using Spheral. Unlike other natural disasters, a threatening asteroid might be prevented if detected early enough through deflection (slight velocity change) or disruption (intentional fragmentation).

NASA's DART mission in 2022 demonstrated a kinetic-impact deflection approach by striking asteroid moon Dimorphos. Nuclear mitigation offers an alternative option for larger objects or shorter warning times, as more energy can be delivered than the kinetic energy of a spacecraft impactor. The simulations revealed signs of disruption in two out of three scenarios, with 98% of the 160-meter asteroid's material damaged and 97% exceeding escape velocity, indicating the asteroid was breaking apart.

The extent of damage and material motion in these cases suggests the asteroid was in the process of disrupting. However, the simulations did not run long enough to determine final fragment sizes, trajectories, or whether debris would reaccumulate. Future work aims to speed up simulations, improve resolution, model more realistic asteroid structures, and compare simulations with small-scale laboratory experiments.