New nuclear deflection simulations advance planetary defense against asteroid threats

Researchers at Lawrence Livermore National Laboratory (LLNL) have developed a modeling tool to evaluate the potential use of a nuclear device to defend the planet against catastrophic asteroid impacts.

The research, published today in the Journal of Planetary Sciences, introduces a new approach to simulate the deposition of energy from a nuclear device on the surface of an asteroid. This new tool improves our understanding of nuclear deflection radiation interactions on the asteroid surface while opening the door to new research into the dynamics of shock waves affecting the asteroid interior.

This model will allow researchers to build on knowledge gained from NASA’s recent Double Asteroid Redirection Test (DART) mission, where, in September 2022, a kinetic impactor deliberately crashed into an asteroid to alter its trajectory . However, given the limits on the mass that can be lifted into space, scientists continue to explore nuclear deflection as a viable alternative to kinetic impact missions.

Nuclear devices have the highest energy density per unit mass ratio of any human technology, making them an invaluable tool for mitigating asteroid threats, said LLNL physicist Mary Burkey, who directed the research.

“If we have enough warning time, we could potentially launch a nuclear device, sending it millions of miles toward an asteroid heading toward Earth,” Burkey said. “We would then detonate the device and either deflect the asteroid, keeping it intact but moving it away from Earth in a controlled manner, or we could disrupt the asteroid, breaking it into small, fast-moving fragments that would also miss the planet. “

Accurate predictions about the effectiveness of nuclear deflection missions rely on sophisticated multiphysics simulations, Burkey said, explaining that LLNL simulation models cover a wide range of physical factors, making them complex and computationally demanding.

The paper presents an efficient and accurate library of X-ray energy deposition functions, developed using the Kull radiation hydrodynamics code. High-fidelity simulations tracked photons penetrating the surfaces of asteroid-like materials such as rock, iron and ice, while accounting for more complex processes, such as reradiation. The model also considers a diverse set of initial conditions, including different porosities, source spectra, radiation fluences, source durations, and incidence angles. This comprehensive approach makes the model applicable to a wide range of potential asteroid scenarios.

Should a true planetary defense emergency occur, high-fidelity simulation modeling will be essential to providing decision-makers with actionable, risk-informed information that could prevent an asteroid impact, protect critical infrastructure, and save lives, explained Megan Bruck Syal of the LLNL Planetary Defense Project. lead.

“Although the likelihood of a significant asteroid impact in our lifetime is low, the potential consequences could be devastating,” Bruck Syal said.

Led by Burkey, the LLNL research team included co-authors Robert Managan, Nicholas Gentile, Bruck Syal, Kirsten Howley and Joseph Wasem.