Asteroid Defense: Comparison of Kinetic-Impact and Nuclear Stand-Off Schemes

Abstract:

In this work we study the deflection of hazardous near-earth objects using either a kinetic impactor or a nuclear stand-off burst. If the object is known to be competent, the kinetic impactor is shown to be highly efficient. The momentum delivered to the object can be much greater than the momentum of the impactor because of the reaction force produced by ablation from the impact crater. We use an adaptive-mesh hydrocode to study the momentum-enhancement factor, or beta, varying the assumptions regarding the equation of state and the strength of the target. Spall from the back side of the asteroid, which partly counters the favorable effect of ablation, is also included in the calculations. For objects not known to be competent, the nuclear stand-off burst option may be preferable. In this case, crucial questions surround the optimum height of burst and the radiation characteristics of the burst. The same hydrocode, with radiation diffusion included, is used to study this case as well. Figures of merit from both these studies include the bulk momentum imparted to the asteroid and the degree to which the asteroid is disrupted.

LA-UR-14-26234