Cross-code Comparisons of Asteroid Deflection and Disruption via X-Ray and Neutron Energy Deposition

Abstract:

A potential asteroid impact is the only natural disaster humans have the ability to completely prevent with enough notice. A kinetic impactor is the preferred method for a mitigation mission, but in the event the approaching object has either a short warning time or is too large for a kinetic impactor to handle, a nuclear device could be utilized. When detonated in the vacuum of space, the neutrons and x-ray photons emitted from the device would deposit energy on the surface of the asteroid, causing some of the material to melt or vaporize. In a deflection mission scenario, the melted/vaporized material rapidly expands from the surface of the asteroid, imparting a push to the asteroid equal to the blow-off momentum while keeping the bulk of the material intact. In a disruption mission scenario, if successful, the deposited energy would be great enough for a shock wave to penetrate into the bulk of the asteroid, break it apart, and thoroughly disperse the fragments. Both scenarios present extremely complicated problems to simulate given their dependency on the asteroid’s size, structure, shape, strength, porosity, and composition, many of which may be unknown before a mission is launched. We present a comparison of energy deposition profiles and reradiation fractions across several materials from Kull and Mercury (a radiation hydrodynamics code and a Monte Carlo particle transport code, respectively) with the resulting deflection or disruption of a sample asteroid when the deposition profiles are input into Spheral, an Adaptive Smoothed Particle Hydrodynamics code.

Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344.

LLNL-ABS-812843