NASA Highlights Gaps in Detection of Mid-Sized 'City-Killer' Asteroids

NASA officials have reported that approximately 15,000 mid-sized near-Earth objects (NEOs), each at least 140 meters wide, remain undetected. These asteroids, often referred to as 'city-killers,' could cause significant regional devastation if they were to impact populated areas.

Dr. Kelly Fast, head of NASA's planetary defense, emphasized the concern over these undetected asteroids during a recent conference. She noted that while large asteroids are well-tracked and smaller ones frequently enter Earth's atmosphere without major consequences, it's the mid-sized objects that pose a substantial risk due to their potential for regional damage.

The Double Asteroid Redirection Test (DART) mission, which successfully altered the orbit of the asteroid moonlet Dimorphos in 2022, demonstrated the feasibility of asteroid deflection. However, Dr. Nancy Chabot of Johns Hopkins University, who led the DART mission, pointed out that there is currently no ready-to-launch spacecraft capable of deflecting a threatening asteroid. She highlighted the need for investment in preparedness for such threats.

The detection of asteroid 2024 YR4, approximately the size of a football field, after it had already passed Earth on December 25, 2024, underscores the gaps in current detection efforts. Although subsequent calculations ruled out a 2032 collision, the incident highlights the necessity for improved monitoring systems.

To address these challenges, NASA plans to launch the Near-Earth Object Surveyor space telescope next year, aiming to enhance the detection and tracking of potentially hazardous asteroids. Currently, the agency has identified only about 40% of objects larger than 140 meters.