Watching the skies for large asteroids that could pose a hazard to Earth is a global endeavor. So, to test their operational readiness, the international planetary defense community will sometimes use a real asteroid's close approach as a mock encounter with a "new" potentially hazardous asteroid. The lessons learned could limit, or even prevent, global devastation should the scenario play out for real in the future. "This real-world scientific input stress-tested the entire planetary defense response chain, from initial detection to orbit determination to measuring the asteroid's physical characteristics and even determining if and where it might hit Earth," said Vishnu Reddy, associate professor at the University of Arizona's Lunar and Planetary Laboratory, who led the campaign.