90007241

open access

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Numerical Simulations of Laboratory-Scale, Hypervelocity-Impact Experiments for Asteroid-Deflection Code Validation

English (英語)

Earth and Space Science

7(4)

e2018EA000474-e2018EA000474

American Geophysical Union (AGU)

2020-04

2020-07-16

Asteroids 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). Plain Language Summary Asteroid and comet impacts into Earth are a low-probability but high-consequence risk. Given that the risk exists, we prepare ahead of time by researching ways to stop a potentially hazardous object from hitting our planet. Conducting experiments in space on actual asteroids or comets to practice mitigation tactics is possible but limited. In the meantime, the planetary defense community uses codes to simulate different ways of stopping these potentially dangerous objects. But this begs the question, how do we know our codes are correct? In an effort to gain confidence in our codes, this work compares our simulation results to data from a well-known laboratory-scale experiment to assess the accuracy of our models. We find that our code can produce results that closely resemble the experimental findings, giving assurance to the planetary defense community that our code can correctly simulate asteroid or comet mitigation.

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