Phoenix, February 17, 2026: Scientists still do not know the location of nearly 15,000 potentially destructive mid-sized asteroids, according to NASA’s head of planetary defence.
Speaking at the American Association for the Advancement of Science conference, Dr Kelly Fast said these near-Earth objects measure at least 140 metres wide — large enough to cause severe regional devastation if they strike a populated area.
Mid-sized threats remain undetected
“It’s really the asteroids that we don’t know about,” Fast said. While larger, extinction-level asteroids are closely tracked and smaller space rocks frequently burn up in Earth’s atmosphere, it is the mid-sized objects that pose a significant but less visible risk.
Currently, NASA has identified only about 40 per cent of near-Earth objects larger than 140 metres. The remaining 60 per cent remain untracked.
Concern intensified in December 2024 when asteroid YR4, roughly the size of a football pitch, was detected shortly after passing Earth. Though later calculations ruled out a potential 2032 impact, the episode highlighted gaps in monitoring systems.
No ready deflection mission available
Dr Nancy Chabot of Johns Hopkins University, who led NASA’s Double Asteroid Redirection Test (DART), noted that while the 2022 mission successfully altered the orbit of asteroid moonlet Dimorphos, no spacecraft is currently ready for launch if a real threat emerges.
“If something were headed towards Earth right now, we would not have the capability to deflect it actively,” she warned, calling for greater investment in planetary defence.
NASA’s upcoming Near-Earth Object Surveyor telescope, expected to launch next year, aims to significantly improve detection rates.
Scientists stress that while there is no immediate known threat, strengthening early-warning systems is critical to preventing future regional disasters.