In a recent alarming update, NASA has warned that approximately 15,000 'city-killer' asteroids, defined as those measuring around 140 meters (approximately 500 feet), remain undetected in near-Earth space. Dr. Kelly Fast, a planetary defense officer at NASA, emphasized the urgency of this issue, stating, "We are concerned about these city-destroying asteroids," and noted that only about 40% of such objects have been tracked. This leaves a staggering 15,000 asteroids unaccounted for, posing a significant threat to urban areas worldwide. The lack of detection capabilities is particularly troubling, as many of these asteroids are dark and blend into the vastness of space, making them difficult to spot until they are dangerously close to Earth. According to the Daily Times, "NASA scientists have issued a sobering warning about thousands of so-called city-killing asteroids that could one day threaten Earth," highlighting the vulnerability of current planetary defense systems.