Asteroid Bennu: When, how and all about asteroid 'most likely to hit Earth'

With the news of asteroid Bennu clobbering the earth, it is but natural to get alarmed and fret. However, there is no reason to be, scientists said in a new study reported Wednesday that the odds are still quite low that Bennu will hit us in the next century. Here's what you need to know.

What is Asteroid Bennu?

101955 Bennu is a carbonaceous asteroid of the Apollo group which was identified on September 11, 1999, by the LINEAR Project. It's a potentially dangerous object with the second-highest cumulative rating on the Palermo Technical Impact Hazard Scale, according to the Sentry Risk Table.

Bennu, the top-shaped rubble pile that orbits the sun in relative solitude, has been doing so for hundreds of millions of years. The asteroid, which is approximately a third of a mile across at its equator, is not a direct threat to Earth. However, there is a slight risk that Bennu will collide with Earth hundreds of years from now.

“Bennu is by far the best-characterized asteroid in the solar system,” University of Arizona planetary scientist Dante Lauretta, OSIRIS-REx’s principal investigator and the study’s senior author, said. “We know where it’s going to be over 100 years into the future, within meters. No other object in the solar system has that level of fidelity to its orbital solution—even Earth!”

When will Bennu hit Earth?

Scientists used data from NASA's OSIRIS-REx spacecraft to construct a precise calculation of Bennu's orbit and future approach to our home planet in a new study published in the scientific journal Icarus. The researchers then looked at the effect risk between now and 2300, National Geographic reported.

Over the following three centuries, the analysis predicts a 1-in-1,750 likelihood of a subsequent collision, which is slightly greater than previously projected. Nearly majority of the most dangerous contacts with Bennu will take place in the late 2100s and early 2200s, with the most likely impact occurring on September 24, 2182. Bennu has a one-in-2,700 chance of colliding with Earth on that Tuesday.

The scientists, led by NASA's Jet Propulsion Laboratory's Davide Farnocchia, arrived at their new estimate by identifying Bennu's distance from Earth to within around seven feet hundreds of times between 2019 and 2020. “If you want to be able to predict where [an asteroid] is going to go in the future, that prediction is entirely determined by how well you can measure where it is today,” said University of Arizona planetary scientist Amy Mainzer, an expert on near-Earth asteroids. “This team has made an extremely precise measurement.”

'Don't worry about it too much'

“We shouldn't be worried about it too much,” said Farnocchia. According to Farnocchia, scientists now have a much better idea of Bennu's path thanks to NASA's Osiris-Rex spacecraft. While the odds of a strike have risen from 1-in-2,700 to 1-in-1,750 over the next century or two, scientists now have a much better idea of Bennu's path thanks to NASA's Osiris-Rex spacecraft, NBC reported. “So I think that overall, the situation has improved," he told reporters.

Bennu, along with another asteroid called 1950 DA, is one of the two most dangerous known asteroids in our solar system, despite the tiny possibilities of it colliding with Earth. If Bennu collides with Earth, it won't wipe out life the way the dinosaurs did, but it will leave a crater 10 to 20 times the size of the asteroid, according to NASA's planetary defense chief, Lindley Johnson. The destruction area would be substantially larger: up to 100 times the size of the crater.

Bennu's magnitude would " pretty much devastate things up and down the coast" if it collided with the Eastern Seaboard, he told reporters. Finding potentially dangerous asteroids ahead of time boosts the odds and alternatives for pushing them out of our way, according to Johnson. “One hundred years from now, who knows what the technology is going to be?” he said.

NASA wants to launch a mission in November to hit an asteroid and throw it off course. The moonlet of larger space rock will be the experimental target.