The asteroid Dimorphous, three months after it was hit by a spacecraft
NASA, ESA, David Jewitt (UCLA), and Alyssa Pagan (STScI)
Last year, NASA’s smashed a spacecraft into the asteroid Dimorphous. Now, the resulting debris has been captured in stunning detail by the Hubble Space Telescope, revealing a glittering field of small boulders.
The Double Asteroid Redirection Test (DART) saw a 600-kilogram spacecraft impact Dimorphous, which orbits a larger asteroid called Didymos, to see if it could alter the space rock’s orbit as a practice run for future dangerous asteroids. The mission was a success, with the length of Dimorphous’ orbit reduced by about 33 minutes following an impact in September 2022.
A few months later, in December 2022, David Jewitt at the University of California at Los Angeles and his colleagues used the Hubble Space Telescope to learn more about the debris expelled by the collision. They found 37 large boulders, ranging in size from 1 to almost 7 metres across, seen as small sparkles of light on the picture above.
The rocks are likely to have been loosely tied to Dimorphous’ surface, rather than shards of rocks from the body of the asteroid itself. They are also moving relatively slowly relative to Dimorphous — at around 0.8 kilometres per hour — and their total mass is around 0.1 per cent of their parent.
“This tells us for the first time what happens when you hit an asteroid and see material coming out up to the largest sizes,” Jewitt said in a statement. “The boulders are some of the faintest things ever imaged inside our solar system.”
This cloud of boulders will be studied further by the European Space Agency’s Hera spacecraft, which will leave Earth in October 2024 and arrive at Didymos and Dimorphous at the end of 2026. By using the Hubble observations taken now and future Hera observations, astronomers might be able to pin down the boulders’ exact trajectories.
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