It's worse than expected: NASA vehicle's collision with an asteroid scattered its debris for thousands of kilometers. Photo

As a result of the collision of the DART (Double Asteroid Redirection Test) spacecraft with the asteroid satellite Dimorphos, 37 large boulders were ejected from the surface of the latter, scattering thousands of kilometers.

The debris was discovered by a group of researchers who studied data from the Hubble telescope. The scientists reported their discovery in an article for The Astrophysical Journal Letters.

The collision between the DART spacecraft and the 160-meter Dimorphos took place on September 26, 2022, and was declared successful, as it allowed the asteroid satellite to be shifted from its original trajectory. In this way, NASA was testing the theory that it is possible to knock an asteroid off course if it threatens the Earth, for example.

Later, however, it turned out that the impact was much stronger, and Dimorphos accelerated its rotation around Didymos not for 7 minutes, as NASA had planned, but for as much as 33 minutes.

Now, thanks to the Hubble telescope, it has been discovered that as a result of the collision, 37 boulders ranging in size from 1 meter to almost 7 meters were ejected from Dimorphos! They were scattered over an area of about 10 thousand kilometers.

At first, the astronauts decided that these were debris that had been bounced off the asteroid as a result of the collision, but it turned out that they were rocks that had been lying on the surface of Dimorphos.

The team of astronomers notes in the article that the boulders are very small by cosmic standards, so they were only seen due to the high sensitivity of the Hubble.

The images of the boulders surrounding Dimorphos were taken on December 19, 2022.

A few moments before the impact, the DRACO DART camera sent an image of Dimorphos showing a surface covered with boulders of various shapes and sizes. Astronomers are not yet sure how the boulders were "lifted" from the asteroid's surface.

It is assumed that they could have been part of a large ejection plume observed by Hubble and several other observatories after the collision. Or, as the scientists suggest, the seismic wave from the impact could have shaken the asteroid and ejected debris.

"The number, size, and shape of the boulders photographed by Hubble are consistent with them being preliminary objects displaced from about 2% of the surface (Dimorphos) by the DART impact," the team wrote in their article.

The scientists also said that the boulders are moving away from the asteroid at a relatively slow speed of 0.8 kilometers per hour.

"This is an impressive observation, much better than I expected. We see a cloud of boulders carrying mass and energy from the impact target. The number, size, and shape of the boulders are consistent with them being knocked off the surface of Dimorphos by the impact," said David Jewitt, a planetary scientist at the University of California, Los Angeles.

DART weighed 610 kg and crashed into Dimorphos at a speed of approximately 22,530 km/h. The collision reduced the asteroid's orbital velocity and reduced its orbital radius.

DART dug a crater on the surface of Dimorphos, which threw more than 990 tons of debris into space. The collision also changed the trajectory of the parent asteroid, Didymos. Thanks to the new data, astronomers are almost certain that Dimorphos is a debris asteroid. These are asteroids that consist of assembled fragments of broken monolithic asteroids and are much more common than previously thought in the solar system.

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