NASA’s Hubble telescope has given in an insight into the aftermath of NASA’s DART mission in which a spacecraft impacted Dimorphos asteroid on September 26, 2022. The mission changed the trajectory of the asteroid’s orbit around the largest asteroid Didymos.
What have astronomers spotted?
Astronomers have seen a swarm of boulders, 37 in number, which were ejected from Dimorphos after NASA slammed its spacecraft into it at a speed of nearly 14,000 miles per hour. The 37 boulders’ sizes range from three feet to 22 feet across, as shown by Hubble photometry. They are moving away from the asteroid at over half-mile per hour. This roughly compares to the walking speed of a giant tortoise, NASA said. The total mass of the boulders is about 0.1% of the mass of Dimorphos. “This is a spectacular observation- much better than I expected. We see a cloud of boulders carrying mass and energy away from the impact target. The numbers, sizes, and shapes of the boulders are consistent with them having been knocked off the surface of Dimorphos by the impact,” University of California at Los Angeles’ David Jewitt said.
NASA says the boulders were most likely already scattered on the surface of the asteroid and are not shattered pieces of it. Jewitt estimates that the impact shook off 2% of the boulders from the asteroid’s surface. He adds that the observations of the boulders give an idea of the size of the crater formed due to DART’s impact. “The boulders could have been excavated from a circle of about 160 feet across (the width of a football field) on the surface of Dimorphos,” he said.
The space agency says it is unclear how the boulders got lifted off the asteroid’s surface. It says they could have been a part of an ejecta plume which was photographed by Hubble and other observatories or a seismic wave caused by the impact may have coursed through the asteroid, shaking lose the surface rubble.
“If we follow the boulders in future Hubble observations, then we may have enough data to pin down the boulders’ precise trajectories. And then we’ll see in which directions they were launched from the surface,” Jewitt said.