Excavating Stickney crater at Phobos

Syal, Megan Bruck; Rovny, Jared; Owen, J. Michael; Miller, Paul L.

doi:10.1002/2016gl070749

“…At low resolution, damage decreases with increasing resolution, until converging at resolutions above approximately 50 particles across the diameter of the target. This trend is consistent with previous work using Spheral, which demonstrated damage can be overestimated with insufficient resolution (Benz & Asphaug, ; Bruck Syal, Owen, et al, ; Bruck Syal, Rovny, et al, ). For this work, we subsequently adopt a resolution of 150 particles across the diameter of the basalt sphere, corresponding to a total number of ~1.75 million particles within the target volume, requiring 512 processors per simulation.…”

Section: Sensitivities In Spheralsupporting

confidence: 92%

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

Remington

¹

,

Owen

²

,

Nakamura

³

et al. 2020

Earth and Space Science

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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).

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“…At low resolution, damage decreases with increasing resolution, until converging at resolutions above approximately 50 particles across the diameter of the target. This trend is consistent with previous work using Spheral, which demonstrated damage can be overestimated with insufficient resolution (Benz & Asphaug, 1995;Bruck Syal, Rovny, et al, 2016). For this work, we subsequently adopt a resolution of 150 particles across the diameter of the basalt sphere, corresponding to a total number of~1.75 million particles within the target volume, requiring 512 processors per simulation.…”

Section: Sensitivities In Spheralsupporting

confidence: 82%

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

Remington

¹

,

Owen

²

,

Nakamura

³

et al. 2019

Preprint

Self Cite

1

0

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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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“…Spheral is an open-source Adaptive Smoothed Particle Hydrodynamics (ASPH) code [Owen et al, 1998;Owen, 2010], which has been used extensively for small-body cratering studies [Owen et al, 2014;Owen et al, 2015;Bruck Syal et al, 2016a;Bruck Syal et al, 2016b]. Meshless hydrodynamics methods such as ASPH allow for the momentum carried in crater ejecta to be calculated in a relatively straightforward manner as the ejecta particles are automatically tracked as they move.…”

Section: Adaptive Smooth Particle Hydrodynamicsmentioning

confidence: 99%

Benchmarking impact hydrocodes in the strength regime: Implications for modeling deflection by a kinetic impactor

Stickle

¹

,

Syal

²

,

Cheng

³

et al. 2020

Icarus

Self Cite

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The Double Asteroid Redirection Test (DART) is a NASA-sponsored mission that will be the first direct test of the kinetic impactor technique for planetary defense. The DART spacecraft will impact into Didymos-B, the moon of the binary system 65803 Didymos and the resulting period change will be measured from Earth. Impact simulations will be used to predict the crater size and momentum enhancement expected from the DART impact. Because the specific material properties (strength, porosity, internal structure) of the Didymos-B target are unknown, a wide variety of numerical simulations must be performed to better understand possible impact outcomes. This simulation campaign will involve a large parameter space being simulated using multiple different shock physics hydrocodes. In order to understand better the behaviors and properties of numerical simulation codes applicable to the DART impact, a benchmarking and validation program using different numerical codes to solve a set of standard problems was designed and implemented. The problems were designed to test the effects of material strength, porosity, damage models, and target geometry on the ejecta following an impact and thus the momentum transfer efficiency. Several important results were identified from comparing simulations across codes, including the effects of model resolution and porosity and strength model choice: 1) Momentum transfer predictions almost uniformly exhibit a larger variation than predictions of crater size; 2) The choice of strength model, and the values used for material strength, are significantly more important in the prediction of crater size and momentum enhancement than variation between codes; 3) Predictions for crater size and momentum enhancement tend to be similar (within 15-20%) when similar strength models are used in different codes. These results will be used to better design a modeling plan for the DART mission as well as to better understand the potential results that may be expected due to unknown target properties. The DART impact simulation team will determine a specific desired material parameter set appropriate for the Didymos system that will be standardized (to the extent possible) across the different codes when making predictions for the DART mission. Some variation in predictions will still be expected, but that variation can be bracketed by the results shown in this study. IntroductionThe Double Asteroid Redirection Test (DART) is a NASA-sponsored mission, currently in Phase C development (as of January, 2019). DART is the first direct test of kinetic impactor technology for planetary defense, and involves the impact of a spacecraft into the moon of a binary system in order to monitor momentum transfer to the target. High-fidelity impact simulations are one tool used to better predict the results of this impact. Because the target of the DART impact is a binary system that has not previously been visited by spacecraft, many of the target properties are unknown and the potential modeling parameter space is large....

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Excavating Stickney crater at Phobos

Cited by 14 publications

References 31 publications

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

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

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

Benchmarking impact hydrocodes in the strength regime: Implications for modeling deflection by a kinetic impactor

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