Earth’s next big threat? NASA says 15,000 ‘city-killer’ asteroids still undetected in space

NASA Warns Thousands Of Potential ‘City-Killer’ Asteroids Still Unknown (Representational Image: Canva)

Scientists have warned that around 15,000 mid sized near Earth asteroids larger than 140 metres remain undiscovered, posing potential regional devastation risks. Speaking at the American Association for the Advancement of Science conference, NASA officials said only 40% of such objects are tracked. While the DART mission proved asteroid deflection is possible, no spacecraft is ready for an emergency response. A recent scare involving asteroid YR4 highlighted gaps in detection efforts, prompting plans for NASA’s Near Earth Object Surveyor telescope.

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Scientists have warned that thousands of potentially destructive “city killer” asteroids remain untracked, raising fresh concerns about planetary defence efforts. Speaking on 16 Feb at the annual meeting of the American Association for the Advancement of Science in Phoenix, officials said major detection gaps still exist despite ongoing surveys and past test missions.

NASA flags risk from mid sized near Earth objects

Dr Kelly Fast, who leads planetary defence at NASA, said about 15,000 mid sized near Earth objects remain undiscovered. These bodies measure at least 140 metres across. An impact from one could devastate a region. She said larger asteroids are mostly tracked already. Smaller debris strikes Earth quite often. The greater concern involves objects in between. These could cause severe regional destruction. They may not trigger global consequences. Yet they still pose serious danger.

Fast told delegates that unknown asteroids present the real risk. Even powerful telescopes cannot easily find them. Many travel in orbits difficult to detect. According to a report by The Telegraph, she stressed that awareness remains incomplete. Only around 40% of objects larger than 140 metres are currently catalogued.

DART mission shows limits of asteroid defence

Dr Nancy Chabot of Johns Hopkins University highlighted further concerns. She led NASA’s Double Asteroid Redirection Test mission. The spacecraft deliberately struck the small moon Dimorphos. It travelled at 14,000 mph on impact. The goal was to alter its orbit. The experiment proved deflection is possible. However, no similar spacecraft stands ready today.

Chabot said there is no immediate launch option. If a threat appeared now, response would stall. She noted that investment remains limited. Preparedness requires sustained funding and planning.

YR4 detection exposes survey gaps

Concern intensified after asteroid YR4 passed Earth. The object approached on 25 Dec 2024. Early projections raised collision fears for 2032. Later analysis ruled out an impact. Scientists said the episode exposed monitoring gaps.

NASA plans to improve detection capability soon. Its Near Earth Object Surveyor telescope is due next year. The mission aims to find hidden asteroids faster. Officials say earlier discovery offers better protection. Without stronger tracking, regional threats could remain unseen.