Measuring ejecta characteristics and momentum transfer in experimental simulation of kinetic impact

Schimmerohn, Martin; Watson, Erkai; Gulde, Max; Kortmann, L.; Schäfer, Frank

doi:10.1016/j.actaastro.2018.01.046

Cited by 5 publications

(4 citation statements)

References 12 publications

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“…In experiments into solid materials, β increases as the impactor size increases. This general trend was noted in the 1960s for aluminum targets (Denardo & Nysmith 1964), with more recent experiments showing the trend for larger impactors (∼3-4.45 cm) into granite (Walker et al 2013(Walker et al , 2020, sandstone (Schimmerohn et al 2019), and concrete (Chocron et al 2019). In total, these experiments revealed a significant size effect on momentum enhancement where β-1 increased as (D/Dscale) a , where D is the projectile diameter, Dscale is a normalization factor, and the exponent a ranges from 0.4 to 0.65 (Walker et al 2013(Walker et al , 2020Chocron et al 2019).…”

Section: Experimental Constraints On βmentioning

confidence: 77%

“…transferred from hypervelocity impacts, as seen both in experimental (e.g.,Schultz et al 2005, Walker & Chochron 2011Holsapple & Housen 2012;Flynn et al 2015;Hoerth et al 2015;Schimmerohn et al 2019;Chourey et al 2020) and numerical (e.g.,Asphaug et al 1998;Jutzi & Michel 2014;Syal et al 2016;Stickle et al 2017;Raducan et al 2019;Caldwell et al 2020;Rainey et al 2020;Luther et al 2022) studies. While the porosity of Didymos is estimated to be about 20%(Naidu et al 2020), the porosity of Dimorphos is still unknown.…”

mentioning

confidence: 99%

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Effects of Impact and Target Parameters on the Results of a Kinetic Impactor: Predictions for the Double Asteroid Redirection Test (DART) Mission

Stickle¹,

DeCoster²,

Burger³

et al. 2022

Planet. Sci. J.

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The Double Asteroid Redirection Test (DART) spacecraft will impact into the asteroid Dimorphos on 2022 September 26 as a test of the kinetic impactor technique for planetary defense. The efficiency of the deflection following a kinetic impactor can be represented using the momentum enhancement factor, β, which is dependent on factors such as impact geometry and the specific target material properties. Currently, very little is known about Dimorphos and its material properties, which introduces uncertainty in the results of the deflection efficiency observables, including crater formation, ejecta distribution, and β. The DART Impact Modeling Working Group (IWG) is responsible for using impact simulations to better understand the results of the DART impact. Pre-impact simulation studies also provide considerable insight into how different properties and impact scenarios affect momentum enhancement following a kinetic impact. This insight provides a basis for predicting the effects of the DART impact and the first understanding of how to interpret results following the encounter. Following the DART impact, the knowledge gained from these studies will inform the initial simulations that will recreate the impact conditions, including providing estimates for potential material properties of Dimorphos and β resulting from DART’s impact. This paper summarizes, at a high level, what has been learned from the IWG simulations and experiments in preparation for the DART impact. While unknown, estimates for reasonable potential material properties of Dimorphos provide predictions for β of 1–5, depending on end-member cases in the strength regime.

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Section: Experimental Constraints On βmentioning

confidence: 77%

mentioning

confidence: 99%

Effects of Impact and Target Parameters on the Results of a Kinetic Impactor: Predictions for the Double Asteroid Redirection Test (DART) Mission

Stickle¹,

DeCoster²,

Burger³

et al. 2022

Planet. Sci. J.

View full text Add to dashboard Cite

show abstract

“…This scenario differs in three regards: (i) DART's impact speed is much larger than the impact speeds in the laboratory experiments, (ii) the experiment is conducted under Earth's gravity, while the DART impact takes place in a low-gravity environment, and (iii) DART's mass is seven orders of magnitude larger than the projectile in the experiments. Previous studies have shown that the momentum enhancement depends on such scale effects (Holsapple & Housen 2012;Housen & Holsapple 2015;Walker et al 2013;Jutzi & Michel 2014;Walker & Chocron 2015;Durda et al 2019;Schimmerohn et al 2019;Chourey et al 2020). To bridge the gap between the different regimes and study the effect on crater size and momentum enhancement, we conducted additional simulations with iSALE, where we (i) increased the velocity up to 7 km s −1 based on the laboratory setup, but kept the impactor mass the same as in the experiment, and (ii) decreased gravity to 5e-5 m s −2 (Table 3 and Figure 5).…”

Section: From Laboratory Scale To the Dart Scalementioning

confidence: 99%

Momentum Enhancement during Kinetic Impacts in the Low-intermediate-strength Regime: Benchmarking and Validation of Impact Shock Physics Codes

et al. 2022

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In 2022 September, the DART spacecraft (NASA’s contribution to the Asteroid Impact & Deflection Assessment (AIDA) collaboration) will impact the asteroid Dimorphos, the secondary in the Didymos system. The crater formation and material ejection will affect the orbital period. In 2027, Hera (ESA’s contribution to AIDA) will investigate the system, observe the crater caused by DART, and characterize Dimorphos. Before Hera’s arrival, the target properties will not be well-constrained. The relationships between observed orbital change and specific target properties are not unique, but Hera’s observations will add additional constraints for the analysis of the impact event, which will narrow the range of feasible target properties. In this study, we use three different shock physics codes to simulate momentum transfer from impactor to target and investigate the agreement between the results from the codes for well-defined target materials. In contrast to previous studies, care is taken to use consistent crushing behavior (e.g., distension as a function of pressure) for a given porosity for all codes. First, we validate the codes against impact experiments into a regolith simulant. Second, we benchmark the codes at the DART impact scale for a range of target material parameters (10%–50% porosity, 1.4–100 kPa cohesion). Aligning the crushing behavior improves the consistency of the derived momentum enhancement between the three codes to within +/−5% for most materials used. Based on the derived mass–velocity distributions from all three codes, we derive scaling parameters that can be used for studies of the ejecta curtain.

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“…A cloud of debris fragments is generated and impacts the witness plate on the right. and sizes of the ejected fragments were determined , Schimmerohn et al, 2018. In these studies, particle tracking was aided by taking advantage of the constant velocities of the ejected fragments to help filter out outliers.…”

Section: Introductionmentioning

confidence: 99%

Trajectory Based 3d Fragment Tracking in Hypervelocity Impact Experiments

Watson

Maas

Schäfer

et al. 2018

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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Collisions between space debris and satellites in Earth’s orbits are not only catastrophic to the satellite, but also create thousands of new fragments, exacerbating the space debris problem. One challenge in understanding the space debris environment is the lack of data on fragmentation and breakup caused by hypervelocity impacts. In this paper, we present an experimental measurement technique capable of recording 3D position and velocity data of fragments produced by hypervelocity impact experiments in the lab. The experimental setup uses stereo high-speed cameras to record debris fragments generated by a hypervelocity impact. Fragments are identified and tracked by searching along trajectory lines and outliers are filtered in 4D space (3D&thinsp;+&thinsp;time) with RANSAC. The method is demonstrated on a hypervelocity impact experiment at 3.2&thinsp;km/s and fragment velocities and positions are measured. The results demonstrate that the method is very robust in its ability to identify and track fragments from the low resolution and noisy images typical of high-speed recording.

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Measuring ejecta characteristics and momentum transfer in experimental simulation of kinetic impact

Cited by 5 publications

References 12 publications

Effects of Impact and Target Parameters on the Results of a Kinetic Impactor: Predictions for the Double Asteroid Redirection Test (DART) Mission

Effects of Impact and Target Parameters on the Results of a Kinetic Impactor: Predictions for the Double Asteroid Redirection Test (DART) Mission

Momentum Enhancement during Kinetic Impacts in the Low-intermediate-strength Regime: Benchmarking and Validation of Impact Shock Physics Codes

Trajectory Based 3d Fragment Tracking in Hypervelocity Impact Experiments

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