SPH Simulation of the Effects of Material Properties and Structure on Bolide Entry Characteristics

Minor bodies, with diameters in the range of 10–100 meters can present a threat to population centers. Upon entry into the Earth’s atmosphere, bodies of this size will typically breakup at high altitudes above the ground. The resulting rapid deposition of kinetic and thermal energy into the atmosphere can produce a blast wave capable of injuring people and damaging structures below, as was the case in the Russian city of Chelyabinsk in 2013. However, the effect of the body’s composition and porosity on its energy deposition and the resulting blast wave is not well understood. In this work, we use the open-source smooth particle hydrodynamics code Spheral++ to simulate the entry of a 70-meter diameter bolide into Earth’s atmosphere. We vary the material properties and structure of the bolide and examine their effects on the energy deposition and the failure mode of the bolide. We also compare spherical, homogeneous bodies to non-spherical bodies with heterogeneous properties to examine the effects of surface roughness and heterogeneity on the breakup time, and thus the energy deposition rate. Our heterogeneous configurations are designed to be representative of the kinds of rubble-piles bolides frequently seen in the main asteroid belt. Preliminary results suggest non-spherical geometries can lead to failure at higher altitudes.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.