New Space and Tech

Predicting asteroid material properties from a DART-like kinetic impact

By Keith Cowing
Press Release
October 3, 2022
Filed under , , , , ,
Predicting asteroid material properties from a DART-like kinetic impact
Example visualizations of the Spheral simulations. One quadrant is clipped out of the simulation to show the interior structure of the asteroid. (a) The setup for our simulations. The asteroid body is in grey, and the impactor is in red. (b) Same as in (a) but zoomed in on the impactor. (c) The results from simulation 11.09. The asteroid is colored by plastic strain, and low-density ejecta is translucent grey. This simulation had a relatively strong and porous asteroid body. (d) The results from simulation 22.05. Colors are the same as in (c). This simulation had a relatively weak asteroid body with low porosity.

NASA’s Double Asteroid Redirection Test (DART) mission is the first full-scale test of the kinetic impactor method for asteroid deflection, in which a spacecraft intentionally impacts an asteroid to change its trajectory.

DART represents an important first step for planetary defense technology demonstration, providing a realistic assessment of the effectiveness of the kinetic impact approach on a near-Earth asteroid. The momentum imparted to the asteroid is transferred from the impacting spacecraft and enhanced by the momentum of material ejected from the impact site. However, the magnitude of the ejecta contribution is dependent on the material properties of the target. These properties, such as strength and shear modulus, are unknown for the DART target asteroid, Dimorphos, as well as most asteroids since such properties are difficult to characterize remotely.

This study examines how hydrocode simulations can be used to estimate material properties from information available post-impact, specifically the asteroid size and shape, the velocity and properties of the impacting spacecraft, and the final velocity change imparted to the asteroid. Across >300 three-dimensional simulations varying seven material parameters describing the asteroid, we found many combinations of properties could reproduce a particular asteroid velocity.
Additional observations, such as asteroid mass or crater size, are required to further constrain properties like asteroid strength or outcomes like the momentum enhancement provided by impact ejecta. Our results demonstrate the vital importance of having as much knowledge as possible prior to an impact mission, with key material parameters being the asteroid’s mass, porosity, strength, and elastic properties.

Kathryn M. Kumamoto, J. Michael Owen, Megan Bruck Syal, Jason Pearl, Cody Raskin, Wendy K. Caldwell, Emma Rainey, Angela Stickle, R. Terik Daly, Olivier Barnouin

Comments: Accepted to the Planetary Science Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Report number: LLNL-JRNL-837536; LA-UR-22-28492
Cite as: arXiv:2209.11876 [astro-ph.EP] (or arXiv:2209.11876v1 [astro-ph.EP] for this version)
Submission history
From: Kathryn Kumamoto
[v1] Fri, 23 Sep 2022 22:01:55 UTC (8,452 KB)

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