Neutron Energy Effects on Asteroid Deflection

Abstract

The impact of the physical geometry of source versus target produced by a nuclear device used for neutron irradiation and energy deposition as a means of asteroid deflection is investigated. This work examines how these geometric profiles change as both the detonation distance and the neutron source energy is changed. Additionally, the effects of profile shaping on asteroid deflection scenarios is investigated. A comparison is made between current approaches for approximating neutron energy deposition in asteroids using direct Monte-Carlo simulations to generate high-fidelity spatial energy deposition profiles. A detonation source is generated at stand-off distances equal to 0.0001, 0.5, and 5 times the radius for a 500-meter-diameter notional silicon-dioxide asteroid target. Two mono-energetic neutron sources, 14.1 MeV deuterium-tritium fusion neutrons, and 1 MeV Watt-fission neutrons, were modeled to explore the impact of neutron energy on the energy deposition profile and resulting material blow-off for asteroid deflection scenarios. Comparison of the resulting source-particle normalized energy deposition profiles reveals that the distributions vary significantly as the neutron energies and distances change. Hydrodynamic results of the asteroid response indicate that the varying energy deposition can significantly affect overall asteroid deflection, thereby suggesting that tailored neutron spectra could be employed to enhance overall asteroid deflection.