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Calibration of iSALE shock physics code to study hyper-velocity collisions in metal-rich asteroids

Presentation #202.05 in the session “Main-Belt Asteroids 3: Very Large Asteroids”.

Published onOct 26, 2020
Calibration of iSALE shock physics code to study hyper-velocity collisions in metal-rich asteroids

Hyper-velocity collisions are a fundamental process in planetary science and responsible for the geological evolution of large asteroids. As such, the selection of the Psyche mission triggered an increased interest to better understand cratering into metallic materials. The 225-km asteroid (16) Psyche is thought to be a metal-rich asteroid [1-2], possibly the collisionally-exposed core of a large, differentiated planetesimal [3-4]. Revised mass and volume estimates combined with radar, spectral and thermal inertia observations suggest that Psyche may have 30-60 vol.% metal [5]. Psyche may be highly-fractured and mostly metallic (Fe-Ni alloys) to explain the current inferred density (3.78 ± 0.34 g/cm3)—a hypothesis that is bolstered by recent impact experiments on Fe-Ni targets [6], in which impacts cause metal cracking thereby introducing bulk porosity. In this work we use the iSALE shock physics code [7-9] to simulate existing laboratory-based impact experiments. We employ the Johnson and Cook strength model [10] to reproduce crater depth and sizes as observed in Fe-Ni targets. Further, we adopt the Collins damage model [8] to explore methods of failure in metals. We demonstrate the complexity and sensitivity of specific strength model parameters (i.e., brittle-ductile and brittle-plastic transition pressures, friction coefficients) in reproducing internal damage structure. Our small-scale calibration simulations can be extrapolated to simulate large-scale collisions on Psyche and is the focus of our ongoing and future work.

  1. Hanȗs et al., 2017, A&A, 601, A114.

  2. Matter et al., 2013, Icarus, 226, 419.

  3. Bell et al., 1989, Asteroids II, 921.

  4. Elkins-Tanton et al., 2017, Lunar and Planetary Science Conference.

  5. Elkins-Tanton et al., 2020, Journal of Geophysical Research (Planets), 125, e06296.

  6. Marchi et al., 2020, Journal of Geophysical Research (Planets), 125, e05927.

  7. Amsden et al., Los Alamos National Laboratories Report, LA-8095:101p. Los Alamos, New Mexico: LANL.

  8. Collins et al., 2004, Meteoritics and Planetary Science, 39, 217.

  9. Wünnemann et al., 2006, Icarus, 180, 514.

  10. Johnson, Cook, Proceedings 7th International Symposium on Ballistics, 1983, 541-547.


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