There is no way to stop thousands of ‘city killer’ asteroids from hitting Earth, NASA scientist warns

Earth’s Blind Spot: NASA Scientist Raises Alarm Over Thousands of Hidden City Killer Asteroids (Image: Canva)

At a science conference in Phoenix, NASA planetary defence officer Kelly Fast warned that around 25,000 mid sized near Earth asteroids capable of regional devastation remain largely undetected, with only 40 percent identified. While large asteroids are tracked and smaller ones burn up harmlessly, these “city killers” pose the greatest concern. Although NASA’s 2022 DART mission proved deflection is possible, experts say no ready to launch system exists if a real threat emerges.

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Scientists warned this week that Earth remains vulnerable to thousands of undetected near Earth asteroids capable of destroying a city, according to reports by the Daily Star, Newsweek and The Sun.

NASA warns over undetected ‘city killer’ asteroids

Speaking at the American Association for the Advancement of Science conference in Phoenix, Kelly Fast said unknown asteroids concern her most. She said larger asteroids are already tracked carefully. Smaller rocks strike Earth frequently without harm. The greater risk lies in mid sized objects. These measure roughly 140 metres across. Scientists call them potential city killers. They could cause severe regional destruction.

Fast estimated about 25,000 such asteroids exist. Only around 40 percent are identified. She said their size complicates detection efforts. Even powerful telescopes struggle to spot them. Many travel alongside Earth around the Sun. This position limits reflected sunlight visibility. Reports by Newsweek and The Sun quoted her concerns.

Near Earth Objects and asteroid 2024 YR4

Most asteroids orbit within the main belt. Some approach Earth’s orbital neighbourhood regularly. These are known as near Earth objects. A smaller group are potentially hazardous asteroids. They exceed 460 feet in width. They pass within 4.6 million miles. Officials say none currently threaten Earth. Paul Chodas of NASA’s CNEOS explained classifications. The label reflects long term orbital shifts. It does not predict imminent impact events.

Attention rose over asteroid 2024 YR4 recently. Early data suggested possible Earth impact risk. Estimates once reached above three percent. NASA later reduced that probability significantly. The agency said no threat exists presently. However, scientists note assessments can change quickly. The James Webb Space Telescope continues monitoring the object. There remains a four percent lunar impact chance. A collision could create a visible flash.

Can NASA deflect a dangerous asteroid

In 2022 NASA tested asteroid deflection methods. The DART spacecraft struck Dimorphos at high speed. The impact altered the moonlet’s orbit successfully. Mission leader Nancy Chabot said readiness remains limited. She noted no similar craft awaits deployment. Without preparation, active deflection proves difficult.

Scientists say sustained funding is essential. Agencies lack resources for constant defence readiness. Experts argue preparation could improve significantly. They warn time to act remains uncertain.