Apophis Planetary Defense Campaign
Authors: Reddy Vishnu , Kelley Michael S. , Dotson Jessie , Farnocchia Davide , Erasmus Nicolas , Polishook David , Masiero Joseph , Benner Lance A. M. , Bauer James , Alarcon Miguel R. , Balam David , Bamberger Daniel , Bell David , Barnardi Fabrizio , Bressi Terry H. , Brozovic Marina , Brucker Melissa J. , Buzzi Luca , Cano Juan , Cantillo David , Cennamo Ramona , Chastel Serge , Chingis Omarov , Choi Young-Jun , Christensen Eric , Denneau Larry , Dróżdż Marek , Elenin Leonid , Erece Orhan , Faggioli Laura , Falco Carmelo , Glamazda Dmitry , Graziani Filippo , Heinze Aren N. , Holman Matthew J. , Ivanov Alexander , Jacques Cristovao , Janse van Rensburg Petro , Kaiser Galina , Kamiński Krzysztof , Kamińska Monika K. , Kaplan Murat , Kim Dong-Heun , Kim Myung-Jin , Kiss Csaba , Kokina Tatiana , Kuznetsov Eduard , Larsen Jeffrey A. , Lee Hee-Jae , Lees Robert C. , de León Julia , Licandro Javier , Mainzer Amy , Marciniak Anna , Marsset Michael , Mastaler Ron A. , Mathias Donovan L. , McMillan Robert S. , Medeiros Hissa , Micheli Marco , Mokhnatkin Artem , Moon Hong-Kyu , Morate David , Naidu Shantanu P. , Nastasi Alessandro , Novichonok Artem , Ogłoza Waldemar , Pál András , Pérez-Toledo Fabricio , Perminov Alexander , Petrescu Elisabeta , Popescu Marcel , Read Mike T. , Reichart Daniel E. , Reva Inna , Roh Dong-Goo , Rumpf Clemens , Satpathy Akash , Schmalz Sergei , Scotti James V. , Serebryanskiy Aleksander , Serra-Ricart Miquel , Sonbas Eda , Szakáts Robert , Taylor Patrick A. , Tonry John L. , Tubbiolo Andrew F. , Veres Peter , Wainscoat Richard , Warner Elizabeth , Weiland Henry J. , Wells Guy , Weryk Robert , Wheeler Lorien F. , Wiebe Yulia , Yim Hong-Suh , Żejmo Michał , Zhornichenko Anastasiya , Zoła Stanisław , Michel Patrick 
Published: May 2022

We describe results of a planetary defense exercise conducted during the close approach to Earth by the near-Earth asteroid (99942) Apophis during 2020 December–2021 March. The planetary defense community has been conducting observational campaigns since 2017 to test the operational readiness of the global planetary defense capabilities. These community-led global exercises were carried out with the support of NASA’s Planetary Defense Coordination Office and the International Asteroid Warning Network. The Apophis campaign is the third in our series of planetary defense exercises. The goal of this campaign was to recover, track, and characterize Apophis as a potential impactor to exercise the planetary defense system including observations, hypothetical risk assessment and risk prediction, and hazard communication. Based on the campaign results, we present lessons learned about our ability to observe and model a potential impactor. Data products derived from astrometric observations were available for inclusion in our risk assessment model almost immediately, allowing real-time updates to the impact probability calculation and possible impact locations. An early NEOWISE diameter measurement provided a significant improvement in the uncertainty on the range of hypothetical impact outcomes. The availability of different characterization methods such as photometry, spectroscopy, and radar provided robustness to our ability to assess the potential impact risk.