Bullseye: NASA’s DART strikes asteroid in historic deflection test

27 Sep 2022

The asteroid moonlet Dimorphos, as seen by the DART spacecraft 11 seconds before impact. Image: NASA/Johns Hopkins APL

NASA’s Bill Nelson said the mission is an ‘unprecedented success for planetary defence’, while Google released a celebratory Easter egg.

NASA’s Double Asteroid Redirection Test (DART) has successfully smashed itself into an asteroid, representing humanity’s first planetary defence test.

Launched 10 months ago, the spacecraft has been on a one-way collision course with Dimorphos, an asteroid 163 metres in diameter.

The DART mission was an experiment to see if an asteroid’s path can be changed by crashing into it, using a technique known as kinetic impact.

Dimorphos, which is not considered a threat to Earth, orbits a 780 metre-wide asteroid called Didymos. This makes it easier to measure the result of the impact due to the resulting change in its orbit.

Early this morning (27 September) Irish time, DART managed to crash 17 metres from its target at a speed of roughly 24,000kph. Mission systems engineer Elena Adams said the result was “basically a bullseye”.

NASA said the mission shows a viable method of changing the collision course of an object that may be headed towards Earth in the future.

“At its core, DART represents an unprecedented success for planetary defence, but it is also a mission of unity with a real benefit for all humanity,” said NASA administrator Bill Nelson.

“As NASA studies the cosmos and our home planet, we’re also working to protect that home, and this international collaboration turned science fiction into science fact, demonstrating one way to protect Earth.”

NASA isn’t the only group celebrating the success of the mission. Google has added an Easter egg to its search engine, so those who search ‘NASA DART’ will get a surprise.

While the DART spacecraft is no longer with us, the mission is far from over. Over the coming weeks, a global team will precisely measure Dimorphos’ orbital change to determine how effectively it was deflected.

In around four years, the European Space Agency’s Hera mission will then survey both Dimorphos and Didymos. NASA said this mission will have a “particular focus” on the crater left by the DART collision, along with a precise measurement of Dimorphos’ mass.

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Leigh Mc Gowran is a journalist with Silicon Republic