NASA has identified September 24, 2182, as the date with the highest individual probability of the asteroid Bennu impacting Earth. While the odds of a collision remain low—roughly 1 in 2,700—the agency maintains active monitoring of the object to refine its long-term trajectory and assess potential gravitational risks.
Calculating the Risk of a 2182 Impact
Within that extended timeline, the date of September 24, 2182, stands out as the moment of greatest concern, carrying a specific impact probability of about 1 in 2,700, or 0.037%. While these figures suggest a low risk, they represent a significant refinement in accuracy compared to the estimates previously generated by ground-based telescopes.
Earth Gravity May Redirect Bennu in 2135
Before any potential 2182 encounter occurs, Bennu is scheduled for a close flyby of Earth in 2135. However, the flyby is critical because it will alter the asteroid’s trajectory through the influence of Earth’s gravity. Scientists are particularly focused on gravitational keyholes, which are narrow regions of space that could redirect the asteroid onto a collision course for future generations if it passes through them during the 2135 event. The task of determining exactly how likely that keyhole passage is became the central focus of the 2021 study.
Accounting for the Yarkovsky Effect
Determining the likelihood of Bennu threading one of these keyholes requires accounting for forces beyond basic orbital mechanics. The most prominent of these is the Yarkovsky effect, where the asteroid absorbs sunlight and radiates it as heat, creating a faint, continuous thrust that shifts its path over centuries.
Probe Collects Samples to Prevent Catastrophic Impact
The American space agency launched a probe toward the asteroid with the explicit goal of collecting samples. The hope behind this mission is that the gathered information could help prevent a possible catastrophic encounter. Experts note that an impact from an object like Bennu could carry a power equivalent to that of 22 atomic bombs. While the probability of an impact is small enough that no one is bracing for an immediate collision, the object remains one of the most thoroughly modeled in the solar system.
Sample Return Helps Study Yarkovsky Effect
On September 24, 2023—exactly 41 years before the date NASA identified as having the highest impact probability—the spacecraft released its sample capsule. This provided laboratories with material to study the physical and thermal properties driving the Yarkovsky effect. Investigators even verified that the touch-and-go
sample-collection maneuver on October 20, 2020, had a negligible effect on the asteroid’s future path.
Scientific visualization and data coordination for the project have involved a wide range of contributors, including researchers from The Johns Hopkins University Applied Physics Laboratory, NASA’s Goddard Space Flight Center, and the Southwest Research Institute. Ongoing observations, coordinated through the Center for Near-Earth Object Studies, are expected to keep refining these impact probabilities long before the 22nd century arrives.