NASA: Thousands of 'city-killer' asteroids undetected, Earth lacks defense

NASA has issued a serious warning about the significant threat posed by thousands of undetected "city-killer" asteroids, which are large enough to cause regional devastation if they were to impact Earth. According to Kelly Fast, acting planetary defense officer for NASA, there are an estimated 25,000 such asteroids, each measuring at least 140 meters in diameter, orbiting near Earth. Alarmingly, NASA has only identified and is tracking approximately 40% of these potentially dangerous objects. The primary challenge in tracking these "city-killer" asteroids lies in their orbital paths, which often make them difficult to detect with current ground-based telescopes. Many of these asteroids orbit in ways that synchronize with Earth's path around the Sun, rendering them invisible to optical telescopes for extended periods. While NASA's Near-Earth Object Surveyor space telescope, scheduled for launch in the coming years, aims to improve detection capabilities by utilizing thermal signatures to identify these "dark" asteroids, a significant gap in monitoring remains. Compounding the concern is the current lack of immediate defense capabilities. While NASA's Double Asteroid Redirection Test (DART) mission in 2022 successfully demonstrated the feasibility of altering an asteroid's trajectory by crashing a spacecraft into it, there are currently no similar spacecraft readily available for deployment if a threatening asteroid were detected on a collision course. Nancy Chabot, a planetary scientist at Johns Hopkins University and leader of the DART mission, has emphasized the need for continued investment and readiness, stating that if an asteroid like YR4 were found to be on a collision course, there would be no immediate solution. The asteroid 2024 YR4 itself served as a recent case study, initially raising alarms with a small but measurable chance of impacting Earth in 2032. While further observations eventually downgraded the risk to zero for Earth, its trajectory did raise concerns about a potential impact with the Moon. This event highlighted the dynamic nature of asteroid threat assessments and the importance of continuous monitoring. NASA's strategy for planetary defense involves multiple pillars, including enhancing detection and tracking of Near-Earth Objects (NEOs), improving characterization of these objects, advancing impact mitigation technologies, improving emergency response, and expanding international cooperation. The agency's Center for Near-Earth Object Studies (CNEOS) plays a crucial role in calculating orbits and assessing impact probabilities. The development of new systems like Sentry-II and the upcoming NEO Surveyor telescope are key components of NASA's long-term plan to bolster planetary defense. While the focus is often on larger, extinction-level asteroids, the threat posed by medium-sized "city-killer" asteroids is significant and requires sustained attention and investment. The lack of immediate deflection capabilities and the challenges in detecting all potentially hazardous objects underscore the ongoing need for advancements in technology and international collaboration to ensure Earth's safety from asteroid impacts. The SSBCrack News article reflects these concerns, bringing attention to the critical need for improved detection and defense strategies.

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