Fast boulder fracturing by thermal fatigue detected on stony asteroids

• Published in: Nature communications Vol. 15; no. 1; pp. 6206 - 11
• Main Authors: Lucchetti, A., Cambioni, S., Nakano, R., Barnouin, O. S., Pajola, M., Penasa, L., Tusberti, F., Ramesh, K. T., Dotto, E., Ernst, C. M., Daly, R. T., Mazzotta Epifani, E., Hirabayashi, M., Parro, L., Poggiali, G., Campo Bagatin, A., Ballouz, R.-L., Chabot, N. L., Michel, P., Murdoch, N., Vincent, J. B., Karatekin, Ö., Rivkin, A. S., Sunshine, J. M., Kohout, T., Deshapriya, J.D.P., Hasselmann, P.H.A., Ieva, S., Beccarelli, J., Ivanovski, S. L., Rossi, A., Ferrari, F., Rossi, C., Raducan, S. D., Steckloff, J., Schwartz, S., Brucato, J. R., Dall’Ora, M., Zinzi, A., Cheng, A. F., Amoroso, M., Bertini, I., Capannolo, A., Caporali, S., Ceresoli, M., Cremonese, G., Della Corte, V., Gai, I., Gomez Casajus, L., Gramigna, E., Impresario, G., Lasagni Manghi, R., Lavagna, M., Lombardo, M., Modenini, D., Palumbo, P., Perna, D., Pirrotta, S., Tortora, P., Zannoni, M., Zanotti, G.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.07.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/33/445/3928; 639/33/445/848; 704/445/536; Asteroid deflection; Asteroid missions; Asteroids; Astrophysics; Boulders; Crack propagation; Earth and Planetary Astrophysics; Fatigue; Fatigue failure; Fatigue tests; Fracture mechanics; Fracturing; Frequency distribution; Humanities and Social Sciences; Impactors; Moonlets; multidisciplinary; Near-Earth Objects; Orientation; Planetary defense; Rocks; Science; Science (multidisciplinary); Sciences of the Universe; Spacecraft; Thermal fatigue; Thermal stress
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-50145-y

Spacecraft observations revealed that rocks on carbonaceous asteroids, which constitute the most numerous class by composition, can develop millimeter-to-meter-scale fractures due to thermal stresses. However, signatures of this process on the second-most populous group of asteroids, the S-complex, have been poorly constrained. Here, we report observations of boulders’ fractures on Dimorphos, which is the moonlet of the S-complex asteroid (65803) Didymos, the target of NASA’s Double Asteroid Redirection Test (DART) planetary defense mission. We show that the size-frequency distribution and orientation of the mapped fractures are consistent with formation through thermal fatigue. The fractures’ preferential orientation supports that these have originated in situ on Dimorphos boulders and not on Didymos boulders later transferred to Dimorphos. Based on our model of the fracture propagation, we propose that thermal fatigue on rocks exposed on the surface of S-type asteroids can form shallow, horizontally propagating fractures in much shorter timescales (100 kyr) than in the direction normal to the boulder surface (order of Myrs). The presence of boulder fields affected by thermal fracturing on near-Earth asteroid surfaces may contribute to an enhancement in the ejected mass and momentum from kinetic impactors when deflecting asteroids. Here, authors study boulders’ fractures on S-type asteroid, Dimorphos, and show that their size-frequency distribution and orientation are consistent with formation through thermal fatigue. Such fractures seem to propagate horizontally much faster (~kyr) than normal to the boulder’s surface (~Myr).