June 24, 2024

NASA Avalanche Asteroid Impact Mission Prompts Space Boulder Surprise : ScienceAlert

A new observation reveals the lingering effect humans have had after intercepting a chunk of rock drifting around the sun last year.

In September 2022, a NASA spacecraft crashed into the asteroid Dimorphos. Hubble on latest comments show a huge swarm of boulders shaken loose by the impact, scattered like stars in the asteroid’s wake.

The new images will help an upcoming mission to the asteroid study the results of the Double Asteroid Redirect Test (DART), to help better screen and plan for such impacts in the future.

“This is a great observation – much better than I expected,” says planetary scientist David Jewitt of the University of California at Los Angeles.

“We see a cloud of boulders carrying mass and energy away from the impact target. The number, sizes and shapes of the boulders are consistent with them having been removed from the surface of Dimorphos by the impact.

“This tells us for the first time what happens when you hit an asteroid and see material come out to the largest sizes. The boulders are some of the smallest objects ever imaged within our Solar System.”

The Hubble image taken in December 2022, circling the boulders. (NASA, ESA, D. Jewitt/UCLA)

The DART mission might have been a lot of fun (and let’s be honest here, it was), but it had a very serious purpose. The aim was to try to knock Dimorphos slightly out of its current orbit around the larger asteroid Didymos, to test how capable we are of doing so in the event that a hazardous asteroid might be heading towards Earth.

The trial was a resounding success. Although Dimorphos and Didymos are still gravitationally bound as a binary asteroid, their previous 7.9-hour orbital period has decreased by 33 minutes. That’s a much more significant result than expected.

We still don’t know much about the impact’s lasting effects, though, so scientists are continuing to monitor the binary asteroid, using telescopes like Hubble to detect the small changes that other instruments might miss.

On December 19, 2022, Hubble took its observations of the object a just releasedshowing a cloud of boulders scattered into space around Dimorphos and Didymos.

Scientists counted 37 rocks, ranging in size from 1 to 6.7 meters (3 to 22 feet) across, slowly moving away from the asteroid at a rate of about 1 kilometer (0.62 miles) per hour.

The rubble, boulder surface of Dimorphos seen in the final full image taken by DART zooming in for impact. (NASA, APL)

Although the DART spacecraft crashed into Dimorphos at a speed of about 22,500 kilometers (14,000 miles) per hour, the asteroid chunk of rubble is probably not broken.

Before the impact, images from DART show loose boulders on the surface of the asteroid; the impact probably dislodged them, although it is not known exactly how. The initial impact may be responsible; or it may have created seismic tremors that laid them out later.

A spacecraft called Hera, which will be launched in 2024, will visit the asteroid to study the results of the impact test.

“The boulder cloud will still be spreading when Hera comes,” says a Jew. “It’s like a swarm of bees that is expanding very slowly and will eventually spread along the binary pair’s orbit around the Sun.”

In the meantime, Hubble’s ongoing checks will help scientists calculate the trajectory of the boulders away from the asteroid so we can figure out exactly where they sailed from – which could help us figure out how they sailed in the first place.

You can download a wallpaper version of the image from the website ESA Hubble website.

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