Journal Article

Elliptical ejecta of asteroid Dimorphos is due to its surface curvature

Dotto, Elisabetta, Abell, Paul A., Deshapriya, J. D. P., Kumamoto, Kathryn M., Barbee, Brent W., Ferrari, Fabio, Ivanovski, Stavro, Jacobson, Seth A., Daly, R. Terik, Tusberti, Filippo, Barnouin, Olivier S., Lucas, Michael P., Michel, Patrick, Raducan, Sabina D., Beccarelli, Joel, Pajola, Maurizio, Senel, Cem Berk, Impresario, Gabriele, Moskovitz, Nicholas A., Marzari, Francesco, Merrill, Colby C., Rivkin, Andrew S., Glenar, David A., Hirabayashi, Masatoshi, Davison, Thomas M., Nakano, Ryota, Gai, Igor, Hasselmann, Pedro H., Farnham, Tony L., Palumbo, Pasquale, Cheng, Andrew F., Chabot, Nancy L., Stickle, Angela M., Makadia, Rahil, Tancredi, Gonzalo, Migliorini, Alessandra, Richardson, Derek C., Lyzhoft, Joshua R., Soldini, Stefania, Jutzi, Martin, Lazzarin, Monica, Pirrotta, Simone, Agrusa, Harrison F., Lolachi, Ramin, Chesley, Steven R., DeCoster, Mallory E., Syal, Megan Bruck, Fahnestock, Eugene G., Sánchez, Paul, Zanotti, Giovanni, Ernst, Carolyn M., Schwartz, Stephen R., Modenini, Dario, Epifani, Elena Mazzotta, Sunshine, Jessica M., Palmer, Eric E., Li, Jian-Yang, Ieva, Simone, Nair, Hari, Lucch

2025

Overview

Kinetic deflection is a planetary defense technique delivering spacecraft momentum to a small body to deviate its course from Earth. The deflection efficiency depends on the impactor and target. Among them, the contribution of global curvature was poorly understood. The ejecta plume created by NASA’s Double Asteroid Redirection Test impact on its target asteroid, Dimorphos, exhibited an elliptical shape almost aligned along its north-south direction. Here, we identify that this elliptical ejecta plume resulted from the target’s curvature, reducing the momentum transfer to 44 ± 10% along the orbit track compared to an equivalent impact on a flat target. We also find lower kinetic deflection of impacts on smaller near-Earth objects due to higher curvature. A solution to mitigate low deflection efficiency is to apply multiple low-energy impactors rather than a single high-energy impactor. Rapid reconnaissance to acquire a target’s properties before deflection enables determining the proper locations and timing of impacts. Double Asteroid Redirection Test (DART) mission impact on asteroid Dimophos resulted in an elliptical ejecta plume. Here, the authors show that this elliptical ejecta is due to the curvature of the asteroid and makes kinetic momentum transfer less efficient.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 639/166/984 / 639/33/445/848 / Asteroid missions / Asteroids / ASTRONOMY AND ASTROPHYSICS / Curvature / Defense / Deflection / Ejecta / Geometry / Humanities and Social Sciences / Impactors / Momentum transfer / multidisciplinary / Near-Earth Objects / Planetary defense / Science / Science (multidisciplinary) / Space telescopes / Spacecraft / Target acquisition / Tracking