Why a Nasa spacecraft will crash into an asteroid in September

The mission will test Earth's defences against celestial threats

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A spacecraft will soon intentionally crash into an asteroid, in a mission that aims to test Earth’s defence against celestial threats.

The Dart, or Double Asteroid Redirection Test, was launched in November last year and is speeding towards a binary asteroid system, located 11 million kilometres from Earth.

It is expected to crash into the space rocks on September 26 (September 27, 3.14am, UAE time) at a speed of 24,000 kilometres an hour — fast enough to travel from New York to Paris in 15 minutes.

The spacecraft will smash into the 160 metre wide “moonlet” Dimorphos, forcing it and its larger companion, Didymos, to shift slightly off course.

Ten days before the impact, the spacecraft will release a CubeSat, a miniature satellite, to capture images of the event.

The Johns Hopkins Applied Physics Laboratory is managing the mission for US space agency Nasa.

“Dart is the world’s first planetary defence test mission, intentionally executing a kinetic impact into Dimorphos to slightly change its motion in space,” Nasa said.

“While neither asteroid poses a threat to Earth, the Dart mission will demonstrate that a spacecraft can autonomously navigate to a kinetic impact on a relatively small target asteroid, and that this is a viable technique to deflect a genuinely dangerous asteroid, if one is ever discovered.”

Scientists have been tracking near-Earth objects for decades to ensure none are on a collision course with the planet.

About 65 million years ago, an asteroid crashed into Earth and killed 70 per cent of all species, including dinosaurs.

More recently, an asteroid crashed into the Russian city of Chelyabinsk in 2013.

The space rock exploded after entering Earth’s atmosphere and released energy equivalent to 500 kilotonnes of TNT.

The incident caused more than 3,600 windows to shatter, injuring more than 1,000 people.

Updated: August 16, 2022, 3:30 AM
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