Last year, NASA smashed a spacecraft into the asteroid Dimorphos. Now, the Hubble Space Telescope has captured the resulting debris in stunning detail, revealing a glittering field of boulders.
The Double Asteroid Redirection Test (DART) saw a 600-kilogram spacecraft impact Dimorphos, which circles a larger asteroid called Didymos, to see if it could alter the space rock’s orbit as a practice run for diverting future dangerous asteroids. The mission was a success, reducing the length of Dimorphos’s orbit by about 33 minutes following impact in September 2022.
A few months later, in December 2022, David Jewitt at the University of California, 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 in the picture above.
It is likely the rocks were loosely tied to Dimorphous’ surface, rather than shards from the body of the asteroid itself. They are also moving slowly relative to Dimorphous at around 0.8 kilometres per hour and their total mass is around 0.1 per cent of their parent asteroid.
“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 is scheduled to leave Earth in October 2024 and arrive at Didymos and Dimorphos 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.