2023 · NATURE

Momentum transfer from the DART mission kinetic impact on asteroid Dimorphos

Cheng, Andrew F., Agrusa, Harrison F., Barbee, Brent W., Meyer, Alex J., Farnham, Tony L., Raducan, Sabina D., Richardson, Derek C., Dotto, Elisabetta, Zinzi, Angelo, Della Corte, Vincenzo, Statler, Thomas S., Chesley, Steven, Naidu, Shantanu P., Hirabayashi, Masatoshi, Li, Jian-Yang, Eggl, Siegfried, Barnouin, Olivier S., Chabot, Nancy L., Chocron, Sidney, Collins, Gareth S., Daly, R. Terik, Davison, Thomas M., DeCoster, Mallory E., Ernst, Carolyn M., Ferrari, Fabio, Graninger, Dawn M., Jacobson, Seth A., Jutzi, Martin, Kumamoto, Kathryn M., Luther, Robert, Lyzhoft, Joshua R., Michel, Patrick, Murdoch, Naomi, Nakano, Ryota, Palmer, Eric, Rivkin, Andrew S., Scheeres, Daniel J., Stickle, Angela M., Sunshine, Jessica M., Trigo-Rodriguez, Josep M., Vincent, Jean-Baptiste, Walker, James D., Wuennemann, Kai, Zhang, Yun, Amoroso, Marilena, Bertini, Ivano, Brucato, John R., Capannolo, Andrea, Cremonese, Gabriele, Dall'Ora, Massimo, Deshapriya, Prasanna J. D., Gai, Igor, Hasselmann, Pedro H., Ieva, Simone, Impresario, Gabriele, Ivanovski, Stavro L., Lavagna, Michele, Lucchetti, Alice, Epifani, Elena M., Modenini, Dario, Pajola, Maurizio, Palumbo, Pasquale, Perna, Davide, Pirrotta, Simone, Poggiali, Giovanni, Rossi, Alessandro, Tortora, Paolo, Zannoni, Marco, Zanotti, Giovanni

Journal
NATURE
Année
2023
Volume
616
Numéro
7957
Pages
457+
Mois
APR 20
DOI
10.1038/s41586-023-05878-z

Abstract

The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on 26 September 2022 as a planetary defence test(1). DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defence, intended to validate kinetic impact as a means of asteroid deflection. Here we report a determination of the momentum transferred to an asteroid by kinetic impact. On the basis of the change in the binary orbit period(2), we find an instantaneous reduction in Dimorphos's along-track orbital velocity component of 2.70 +/- 0.10 mm s(-1), indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact(3,4). For a Dimorphos bulk density range of 1,500 to 3,300 kg m(-3), we find that the expected value of the momentum enhancement factor, beta, ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg m(-3), beta = 3.61(-0.25)(+0.19). These beta values indicate that substantially more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos.

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