Set for multiple close encounters with Earth over the next hundred years, there is a chance - however vanishingly small - that the asteroid Bennu could one day collide with our planet.
But don’t worry—NASA has a plan to save us all. And it involves nukes.
Very small risk of collision
NASA lists 78 dates on which Bennu has a tiny chance of colliding with Earth. Taken together, they give an impact risk of one in 2700—small, but not impossible.
Asteroid impacts can be devastating. Some 66 million years ago, the impact of a 9-mile asteroid is widely believed to have wiped out most of Earth’s dinosaurs. In 2013, a 65-ft asteroid entered the skies above Russia, exploding over Chelyabinsk Oblast. The blast caused extensive damage and injured nearly 1,500 people.
Called the Hypervelocity Asteroid Mitigation Mission for Emergency Response, or HAMMER, the "impactor" spacecraft would be deployed to deflect a small asteroid with its own bulk. In certain cases, however, it would set off a nuclear weapon.“If the asteroid is small enough, and we detect it early enough, we can do it with the impactor,” physicist and study co-author David Dearborn of the Lawrence Livermore National Laboratory told BuzzFeed News. “The impactor is not as flexible as the nuclear option when we really want to change the speed of the body in a hurry.”
“You have to be careful not to slow it down just enough to go from hitting the [side] of the Earth to hitting its center,” Dearborn said.
The growing field of planetary protection
Researchers modelled their work on Bennu because the asteroid is the best-studied near Earth object. It zipped past Earth in 1999 and again in 2005, but it won’t have another close encounter until 2054, NASA predicts. In September 2135 it may come as close as one-third the distance to the moon.
“Smart people are taking this seriously and thinking carefully about what might be done,” MIT impact expert Richard Binzel, who was not involved in the study, told BuzzFeed News. “These are reasonable ideas—well thought out.”
“Hopefully we won't need an asteroid deflection plan,” he added. “But until we search, we don't know.”
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