NASA’s mission to collide with asteroid sent ‘swarm of boulders’ into space

Written by ABC Audio. All rights reserved. on July 25, 2023

(NEW YORK) — A “swarm of boulders” was sent careening into space after NASA successfully disrupted the orbit of an asteroid last year, according to the space agency.

The Double Asteroid Redirection Test spacecraft, or DART, collided with Dimorphos, a small asteroid that is the moon of a bigger space rock, Didymos, at about 14,000 miles per hour.

Not only did the test successfully change the trajectory of the orbit but about 37 boulders were shaken off the asteroid in images captured by the Hubble telescope, NASA said.

The boulders range in size from three feet to 22 feet across and are drifting away from the asteroid at about half a mile per hour.

David Jewett, a planetary scientist at the University of California, Los Angeles, who has been tracking changes after the DART mission with the Hubble telescope, told ABC News the trail of the impact had been studied for months and no boulders were noticed.

“So, you know, the impact was at the end of September and I noticed the boulders in data from December, so it’s a long time after — you would think — everything should be over,” he said. “Impact is an impulse, it’s an instantaneous bang. So you would think, naively, you will be able to see it all straight away.”

What’s more, he said the boulders were not in any predictions for what the impact would look like.

The boulders were likely already scattered across the surface of the asteroid rather than chunks of the asteroid that broke off after the impact, according to NASA.

While the boulders are not a threat to Earth, the images are a reminder that future asteroid impact missions could have similar aftereffects.

Jewitt said this is among the first times scientists know just about all details of the impact and are able to see what happens when it’s caused by humans.

“We’ve seen other examples of impact between one asteroid and another and the trouble there is we don’t know when the impact occurred,” Jewitt said. “We see the debris but at some uncertain time after the impact, so the interpretation is clouded by not knowing when it happened, not knowing how big or how energetic the two asteroids were when they collided and so on, so it’s not very well characterized.”

“So, this is a case where, you know, we know the mass of the spacecraft, we know the speed of the spacecraft, so we know the energy. We know quite a lot about the impact,” he continued. “And then the idea is to look at the consequences of a well-calibrated impact to see how the asteroid responds.”

Jewitt added this will be something the European Space Agency’s upcoming Hera mission will investigate.

The Hera mission will examine the asteroid for future asteroid deflection missions, although the mission is launching on October 2024 and will not reach the sight of the impact until December 2026, according to the ESA.

“They’re gonna fly through these boulders on the way to seeing the targeted asteroid called Dimorphos and so … maybe they can study some of these boulders and figure out their properties better than we can get them from the ground,” Jewitt said. “It’s just a question of characterizing the products of a manmade impact into an asteroid to the best possibility that we can.”

ABC News’ Max Zahn contributed to this report.