For hundreds of millions of years, a top-shaped rubble pile called Bennu has orbited the sun in relative isolation. The asteroid, about a third of a mile wide at its equator, poses no immediate threat to our planet. But hundreds of years from now, there is a small chance that Bennu could slam into Earth.
In a new study published in the scientific journal Icarus, scientists used data from NASA’s OSIRIS-REx spacecraft to make a precise calculation of Bennu’s orbit and its future proximity to our home planet. The researchers then analyzed the impact hazard between now and the year 2300. The study finds a 1-in-1,750 chance of a future collision over the next three centuries—a slightly higher probability than previously estimated.
Nearly all of the riskiest encounters with Bennu will occur in the late 2100s and early 2200s, with the single likeliest impact coming on the afternoon of September 24, 2182. On that Tuesday, Bennu has about a 1-in-2,700 chance of hitting Earth.
The team—led by Davide Farnocchia, a navigation engineer at NASA’s Jet Propulsion Laboratory—reached its revised estimate by pinpointing Bennu’s distance from Earth to within about seven feet at dozens of times between 2019 and 2020. That level of precision is like measuring the distance between the Empire State Building and the Eiffel Tower to within a few thousandths of an inch.
“Bennu is by far the best characterized asteroid in the solar system,” says University of Arizona planetary scientist Dante Lauretta, OSIRIS-REx’s principal investigator and the...