Abstract

AbstractAsteroids and comets have the potential to impact Earth and cause damage at the local to global scale. Deflection or disruption of a potentially hazardous object could prevent future Earth impacts, but due to our limited ability to perform experiments directly on asteroids, our understanding of the process relies upon large‐scale hydrodynamic simulations. Related simulations must be vetted through code validation by benchmarking against relevant laboratory‐scale, hypervelocity‐impact experiments. To this end, we compare simulation results from Spheral, an adaptive smoothed particle hydrodynamics code, to the fragment‐mass and velocity data from the 1991 two‐stage light gas‐gun impact experiment on a basalt sphere target, conducted at Kyoto University by Nakamura and Fujiwara. We find that the simulations are sensitive to the selected strain models, strength models, and material parameters. We find that, by using appropriate choices for these models in conjunction with well‐constrained material parameters, the simulations closely resemble with the experimental results. Numerical codes implementing these model and parameter selections may provide new insight into the formation of asteroid families (Michel et al., 2015, https://doi.org/10.2458/azu_uapress_9780816532131‐ch018) and predictions of deflection for the Double Asteroid Redirection mission (Stickle et al., 2017, https://doi.org/10.1016/j.proeng.2017.09.763).

Highlights

  • We rely on computer modeling to assess how to deflect or disrupt a hazardous asteroid in order to prevent the possibility of it impacting Earth

  • We model these experiments using Spheral (Owen, 2010, 2014; Owen et al, 1998), an open‐source adaptive smoothed particle hydrodynamics (ASPH) code available on GitHub, well suited to track stresses and strains during deformation of solids

  • We begin by comparing the simulation results of the damage morphology for the two strain‐model selections available in Spheral to the high‐speed photographs taken during the experiment, as well as the recovered fragment data from the experiments

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Summary

Key Points:

We investigated the accuracy of our code by comparing our simulation results to data from a 1991 hypervelocity experiment. The simulation results indicate that our code can produce results that closely resemble the experimental findings. This work provides insight into model and material parameter selections in our code, potentially applicable in other numerical models. Numerical Simulations of Laboratory‐Scale, Hypervelocity‐Impact Experiments for Asteroid‐Deflection Code Validation. Lawrence Livermore National Laboratory, WCI, Livermore, CA, USA, 2Graduate School of Science and Technology, Kobe University, Kobe, Japan

Introduction
Benchmarking the Experiment
Sensitivities in Spheral
Strain Models
Strength Models and Parameter Selection
Weibull Parameters
Conclusion
Full Text
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