Bennu Asteroid Threat Assessment
In August 2021, NASA updated impact probability assessments for asteroid Bennu, revealing a 1-in-1,750 chance (~0.057%) of Earth impact on September 24, 2182—the highest-probability potentially hazardous asteroid currently tracked. The announcement highlighted both the threat asteroids pose and our improving ability to predict and potentially prevent collisions.
Bennu, a 500-meter-wide carbonaceous asteroid, orbits the Sun every 1.2 years in a path crossing Earth’s orbit. OSIRIS-REx spacecraft observations (2018-2021) refined Bennu’s trajectory predictions through 2300, identifying the 2182 close approach as most concerning. While 0.057% odds seem low, they’re 10x higher than typical near-Earth asteroids.
The updated assessment demonstrated progress in planetary defense: tracking 27,000+ near-Earth asteroids, calculating multi-century trajectories, and developing mitigation technologies. NASA’s DART (Double Asteroid Redirection Test) mission in 2022 successfully demonstrated asteroid deflection capability—ramming a spacecraft into Dimorphos to alter its orbit.
Social media generated 25+ million impressions mixing concern, humor (“mark your calendars for September 2182”), and discussion of planetary defense strategies. Scientists emphasized 1-in-1,750 odds mean 99.94% probability of missing Earth, and 161 years allows plenty of time for deflection missions if refined calculations increase risk.
Bennu’s threat illustrates the “dinosaur problem”—asteroid impacts are rare but catastrophic. A 500-meter impactor would devastate regional areas but not cause mass extinction. By 2023, surveys suggested we’ve found 95%+ of kilometer-scale “extinction-level” asteroids, with none currently threatening Earth. Smaller asteroids like Bennu remain abundant and harder to detect but pose localized rather than existential risks.