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UArizona helps defend against killer asteroids

Osiris Rex assesses threat from Bennu
Posted at 7:47 PM, Aug 11, 2021
and last updated 2021-08-11 22:47:16-04

TUCSON, Ariz — A University of Arizona space probe that grabbed an asteroid sample has been helping scientists look out for our safety. Osiris Rex helped scientists conclude there’s not much chance the Asteroid Bennu will hit us but we’d better keep an eye out for other space rocks.

Osiris Rex eased up to Bennu and grabbed a sample to bring to Earth. Scientists say when the sample arrives in two years it may help explain how life and the universe formed.

But before the sampling the spacecraft had other work to do. It spent about two years orbiting Bennu to learn more about how asteroids move through space and how we might deflect an asteroid that could hit the Earth.

They studied Bennu because it will come so close it will pass between the Earth and the moon, 114 years from now.

Odds are 99.9 percent it will miss us unless it goes through what scientists call a keyhole---a spot where Earth’s gravity could change Bennu’s course just enough to bring it in for a hit 161 years from now.

Scientists are working on ways to steer killer asteroids away from us. University of Arizona planetary scientist Dante Lauretta leads the Osiris Rex mission. He says one possibility may be to take advantage of the way heating and cooling can change an asteroid’s path.

“So think of a parking lot in Tucson in the summertime, and then at night, that energy goes back out into space as heat, and that provides a thrust, which will change the orbital velocity of the asteroid, so it's a definitely legitimate strategy if you could control that you could direct where the heat is injected back into space, and maybe use that to read, design the trajectory and avoid an impact in the future.”

Lauretta says the mission chose Bennu because there was a risk it could hit Earth but now that they know more about Bennu they’re more worried about new asteroids we don’t know about.

Osiris Rex may be able to help protect against them too. Once it’s dropped off its sample of Bennu it has enough fuel to fly out to new asteroids.

Lauretta says, “Osiris Rex is a very healthy spacecraft, does it still have good science instruments? All of our science instruments are in great shape, with a few rare exceptions for things that happened while we were at Bennu and we're well aware of.”

Lauretta expects NASA to rule next year on whether it will budget resources to send Osiris Rex back out to to study other asteroids that could threaten Earth

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