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The potential for a devastating asteroid impact, once relegated to the realm of science fiction, is receiving renewed attention from NASA. Planetary defense officials have issued a stark warning: thousands of near-Earth asteroids, large enough to inflict significant regional damage, remain undetected, and currently, there’s no readily available way to prevent a strike should one be on a collision course with Earth. The agency estimates around 15,000 of these “city-killer” asteroids are unaccounted for, posing a persistent, if statistically low, threat.
Dr. Kelly Swift, head of planetary defense at NASA, highlighted the concern during a presentation at the American Association for the Advancement of Science (AAAS) conference in Arizona last week. She explained that the greatest worry isn’t the large asteroids that are already tracked, nor the frequent, smaller space rocks that burn up in the atmosphere, but rather those in the intermediate size range – approximately 140 meters (460 feet) in diameter or larger. These asteroids are large enough to cause substantial regional devastation, yet compact enough to evade current detection methods. “What keeps me up at night is the asteroids we don’t realize about,” Fast said, according to reporting from the Novel York Post.
These mid-sized asteroids present a unique challenge. NASA estimates there are roughly 25,000 asteroids of this size in near-Earth space, but scientists have only identified about 40% of them. The difficulty lies in their size and orbital characteristics. They are often obscured by the glare of the sun, making them hard to spot even with the most powerful telescopes. As Dr. Fast explained, “It takes time to uncover them, even with the best telescopes.”
The DART Mission: A Proof of Concept, Not a Ready Solution
Whereas the situation may sound dire, it’s not entirely without hope. In 2022, NASA successfully demonstrated the feasibility of asteroid deflection with the Double Asteroid Redirection Test (DART) mission. The spacecraft intentionally collided with the asteroid moonlet Dimorphos, successfully altering its orbit. MSN reports that the impact shifted Dimorphos’ orbit, proving that humanity *can* alter an asteroid’s trajectory. However, Dr. Nancy Chabot, DART mission coordination lead at Johns Hopkins University, cautioned that this capability isn’t currently available for rapid deployment. “DART was a great demonstration, but we don’t have that sitting around ready to go if there was a threat we needed to use it for,” she said.
The DART mission, while a significant achievement, was a single test case. There isn’t currently a dedicated spacecraft on standby, equipped and ready to intercept and deflect a potentially hazardous asteroid. Roughly 50% of asteroids measuring around 140 meters in diameter remain undiscovered, according to Chabot. This lack of comprehensive detection and readily available deflection technology leaves Earth vulnerable.
The Near-Earth Object Surveyor Telescope: A Future Solution
To address the detection gap, NASA is developing the Near-Earth Object Surveyor space telescope, slated for launch next year. This telescope will utilize thermal signatures to identify dark asteroids and comets that are currently hidden from view. NASA hopes this new technology will significantly improve our ability to catalog and track potentially hazardous objects.
The agency acknowledges, however, that even with improved detection capabilities, a rapid response system for asteroid deflection remains a significant challenge. Dr. Fast emphasized the need for continued investment in planetary defense, stating, “We could be prepared, but I don’t see that investment being made.”
The threat posed by these undetected asteroids is a long-term concern, and while the probability of a catastrophic impact in the near future is low, the potential consequences are severe enough to warrant continued vigilance and investment in planetary defense systems. The launch of the Near-Earth Object Surveyor telescope represents a crucial step forward, but a comprehensive strategy for both detection and deflection is essential to safeguard our planet.
What comes next will depend on the data gathered by the Surveyor telescope and the prioritization of planetary defense initiatives. Continued research and development of deflection technologies will be critical, as will international collaboration to address this global threat. Share your thoughts on this developing story in the comments below.
