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Odds of asteroid Bennu clobbering Earth are now higher but still slim

The bad news is the space rock has a slightly greater chance of slamming into us than previously thought. But the chances of that are still pretty low for the next century.

The asteroid Bennu as seen from NASA’s OSIRIS-REx spacecraft.
The asteroid Bennu as seen from NASA’s OSIRIS-REx spacecraft.
NASA/Goddard/University of Arizona/CSA/York/MDA via AP

CAPE CANAVERAL, Fla. — Scientists say the chances of the asteroid Bennu clobbering Earth are slightly greater than previously thought but still pretty slim for the next century.

“We shouldn’t be worried about it too much,” said Davide Farnocchia, a scientist with NASA’s Center for Near Earth Object Studies at the Jet Propulsion Laboratory in Pasadena, California, the lead author of a new study that projected Bennu’s whereabouts over the next 200 years.

Though the odds of a strike have risen a bit over the next century or two, scientists now have a much better idea of Bennu’s path thanks to NASA’s Osiris-Rex spacecraft, according to Farnocchia.

“So I think that overall the situation has improved,” he said.

The spacecraft is headed back to Earth on a long, roundabout loop after collecting samples from the large, spinning rubble pile of an asteroid, which is considered one of the two most hazardous known asteroids in our solar system. The samples aren’t due to be brought back to Earth till 2023.

Before Osiris-Rex arrived at Bennu in 2018, telescopes provided solid insight into the asteroid, which is about one-third of a mile in diameter. The spacecraft collected enough data over two and a half years to help scientists better predict the asteroid’s orbital path well into the future.

Their findings — published in the journal Icarus — also should help chart the course of other asteroids and give Earth more of a fighting chance if another hazardous space rock heads our way.

Before Osiris-Rex arrived on the scene, scientists put the odds of Bennu hitting Earth through the year 2200 at one-in-2,700. Now, the chances are one-in-1,750 through the year 2300.

The single most menacing day? Sept. 24, 2182.

Bennu will have a close encounter with Earth in 2135, when it passes within half the distance of the moon. Earth’s gravity could tweak its future path and put it on a collision course with Earth in the 2200s — less likely now based on Osiris-Rex observations.

If Bennu did slam into Earth, it wouldn’t wipe out life, dinosaur-style, but instead would create a crater roughly 10 to 20 times the size of the asteroid, said Lindley Johnson, NASA’s planetary defense officer. The area of devastation would be much bigger: as much as 100 times the size of the crater.

If an object Bennu’s size hit the Eastern Seaboard, it “would pretty much devastate things up and down the coast,” according to Johnson.

Scientists already are ahead of the curve with Bennu, which was discovered in 1999. Finding threatening asteroids in advance increases the chances and options for pushing them out of our way, Johnson said.

“One-hundred years from now, who knows what the technology is going to be?” he said.

In November, NASA plans to launch a mission to knock an asteroid off-course by hitting it. The experimental target will be the moonlet of a bigger space rock.