Inferring interiors and structural history of top-shaped asteroids from external properties of asteroid (101955) Bennu

• Published in: Nature communications Vol. 13; no. 1; pp. 4589 - 12
• Main Authors: Zhang, Yun, Michel, Patrick, Barnouin, Olivier S., Roberts, James H., Daly, Michael G., Ballouz, Ronald-L., Walsh, Kevin J., Richardson, Derek C., Hartzell, Christine M., Lauretta, Dante S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.08.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/33/445/210; 639/33/445/536; 639/33/445/848; Apollo asteroids; Asteroids; Astrophysics; Cohesion; Earth and Planetary Astrophysics; Evolution; Friction; Geophysics; Humanities and Social Sciences; Interiors; multidisciplinary; Reconfiguration; Science; Science (multidisciplinary); Sciences of the Universe
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-32288-y

Asteroid interiors play a key role in our understanding of asteroid formation and evolution. As no direct interior probing has been done yet, characterisation of asteroids’ interiors relies on interpretations of external properties. Here we show, by numerical simulations, that the top-shaped rubble-pile asteroid (101955) Bennu’s geophysical response to spinup is highly sensitive to its material strength. This allows us to infer Bennu’s interior properties and provide general implications for top-shaped rubble piles’ structural evolution. We find that low-cohesion (≲0.78 Pa at surface and ≲1.3 Pa inside) and low-friction (friction angle ≲ 35 ∘ ) structures with several high-cohesion internal zones can consistently account for all the known geophysical characteristics of Bennu and explain the absence of moons. Furthermore, we reveal the underlying mechanisms that lead to different failure behaviours and identify the reconfiguration pathways of top-shaped asteroids as functions of their structural properties that either facilitate or prevent the formation of moons. Asteroid interiors are key to understand their formation and evolution. Here, the authors show that numerically simulated low-cohesion and low-friction structures with several high-cohesion internal zones can explain asteroid Bennu’s geophysical characteristics and the absence of the moons.