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25th Sep 2022

NASA will smash spacecraft into asteroid in ‘earth-saving’ mission

April Curtin

Illustration of NASA’s DART spacecraft and the Italian Space Agency’s (ASI) LICIACube prior to impact at the Didymos binary system. Credits: NASA/Johns Hopkins APL/Steve Gribben

‘This demonstration is extremely important to our future here on the earth’

NASA is preparing to intentionally smash a spacecraft into a small asteroid, in a project that could save our future on Earth.

The Double Asteroid Redirection Test, or DART mission, will see the spacecraft collide with an asteroid called Dimorphos on Monday evening. While Dimorphos is harmless, space scientists hope the test will prove the method can be used to deter asteroids that are heading for Earth, and could therefore one day save our planet from an asteroid strike capable of ending humanity.

The $330 million mission is the first of its kind and will test if asteroid deflection – also known as the kinetic impactor technique – is a viable way of protecting our planet from asteroids. The technique should change the speed of the asteroid in space, and therefore change the asteroid’s orbit.

Speaking at a press conference about the mission on Thursday, NASA planetary defense officer Lindley Johnson said: “This demonstration is extremely important to our future here on the earth, and life on earth.”

Dart should hopefully strike Dimorphos at 7.14pm EDT on Monday, at a whopping 14,000 miles per hour. NASA and other agencies will then watch in the aftermath using telescopes on the ground and in space to see if the impact changes the speed at which Dimorphos orbits its larger asteroid companion Didymos.

Dart’s impact will be considered successful if it changes Dimorphism’s orbit around Didymos anywhere from 73 seconds to 10 minutes, because even just a small velocity change can change an asteroid’s arrival time enough to change it from an impact to a clear miss.

Speaking at the conference, Dr Johnson explained Dart has been specifically sized to have the desired effect on this particular asteroid, and that if we were faced with a real asteroid threat, “It would depend on the size of the asteroid how much we would need to hit it.

“In the case of the kinetic impactor, it probably need to be larger than Dart, and we also might hit it with several kinetic impactors,” he said.

Scientists of course have many other methods that they are exploring.

One a “gravity tractor”, Dr Johnson explained, “which is just taking a spacecraft keeping with the asteroid and using nature’s tug rope, gravity, the mutual attraction between the spacecraft and the asteroid will slowly tug that asteroid out of its impacting trajectory into a more benign one.”

But the key is also knowing where all the potentially threatening asteroid are, and currently, there are just over 2,250 potentially hazardous asteroids near Earth that scientists are aware of. NASA hopes its upcoming mission ‘Near Earth Object Surveyor’, which is a space telescope currently in its preliminary design review phase, will help scientists discover any asteroids that could be hiding in the glare of the Sun, and give them sufficient time to deal with them in the best possible way.

So thankfully, scientists reassure us that it shouldn’t be as chaotic as it looks in the disaster films.

“Hollywood and movies, they have to make it exciting,” Dr Johnson said, “You know, we find the asteroid only 18 days before it’s going to impact and everybody runs around as if they’re on fire.

“That’s not the way to do planetary defence.”

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