Apophis Planetary Defense Campaign

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