arXiv · 2105.05997
The impact and recovery of asteroid 2018 LA
Abstract
The June 2, 2018, impact of asteroid 2018 LA over Botswana is only the second asteroid detected in space prior to impacting over land. Here, we report on the successful recovery of meteorites. Additional astrometric data refine the approach orbit and define the spin period and shape of the asteroid. Video observations of the fireball constrain the asteroid's position in its orbit and were used to triangulate the location of the fireball's main flare over the Central Kalahari Game Reserve. 23 meteorites were recovered. A consortium study of eight of these classifies Motopi Pan as a HED polymict breccia derived from howardite, cumulate and basaltic eucrite, and diogenite lithologies. Before impact, 2018 LA was a solid rock of about 156 cm diameter with high bulk density about 2.85 g/cm3, a relatively low albedo pV about 0.25, no significant opposition effect on the asteroid brightness, and an impact kinetic energy of about 0.2 kt. The orbit of 2018 LA is consistent with an origin at Vesta (or its Vestoids) and delivery into an Earth-impacting orbit via the nu_6 resonance. The impact that ejected 2018 LA in an orbit towards Earth occurred 22.8 +/- 3.8 Ma ago. Zircons record a concordant U-Pb age of 4563 +/- 11 Ma and a consistent 207Pb/206Pb age of 4563 +/- 6 Ma. A much younger Pb-Pb phosphate resetting age of 4234 +/- 41 Ma was found. From this impact chronology, we discuss what is the possible source crater of Motopi Pan and the age of Vesta's Veneneia impact basin.
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Peter Jenniskens, Mohutsiwa Gabadirwe, Qing-Zhu Yin, Alexander Proyer, Oliver Moses, Tomas Kohout, Fulvio Franchi, Roger L. Gibson, Richard Kowalski, Eric J. Christensen, Alex R. Gibbs, Aren Heinze, Larry Denneau, Davide Farnocchia, Paul W. Chodas, William Gray, Marco Micheli, Nick Moskovitz, Christopher A. Onken, Christian Wolf, Hadrien A. R. Devillepoix, Quanzhi Ye, Darrel K. Robertson, Peter Brown, Esko Lyytinen, Jarmo Moilanen, Jim Albers, Tim Cooper, Jelle Assink, Läslo Evers, Panu Lahtinen, Lesedi Seitshiro, Matthias Laubenstein, Nggie Wantlo, Phemo Moleje, Joseph Maritinkole, Heikki Suhonen, Michael E. Zolensky, Lewis Ashwal, Takahiro Hiroi, Derek W. Sears, Alexander Sehlke, Alessandro Maturilli, Matthew E. Sanborn, Magdalena H. Huyskens, Supratim Dey, Karen Ziegler, Henner Busemann, My E. I. Riebe, Matthias M. M. Meier, Kees C. Welten, Marc W. Caffee, Qin Zhou, Qiu-Li Li, Xian-Hua Li, Yu Liu, Guo-Qiang Tang, Hannah L. McLain, Jason P. Dworkin, Daniel P. Glavin, Philippe Schmitt-Kopplin, Hassan Sabbah, Christine Joblin, Mikael Granvik, Babutsi Mosarwa, Koketso Botepe. 2021-05-12. The impact and recovery of asteroid 2018 LA. https://doi.org/10.1111/maps.13653
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