Hubble and Webb images reveal DART’s impact larger than expected: ScienceAlert

Hubble and Webb images reveal DART's impact larger than expected: ScienceAlert
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James Webb and Hubble telescopes on Thursday released the first images the intentional crash of a spacecraft asteroidAs astronomers note, the effect appears to be much larger than expected.

The world’s telescopes turned their sights on the Dimorphos space rock earlier this week for a historic test of Earth’s ability to defend itself against a potentially life-threatening asteroid in the future.

Astronomers were delighted Monday night when NASA’s Double Asteroid Redirection Test (DART) impactor slammed into its pyramid-sized, rugby-ball-shaped target 11 million kilometers (6.8 million miles) from Earth.

Images taken by ground-based telescopes showed a large cloud of dust expanding from Dimorphos and its orbiting older sibling Didymos after the spacecraft was hit.

Alan Fitzsimmons, an astronomer at Queen’s University Belfast who took part in the observations with the ATLAS project, says that while these images show matter scattered over thousands of kilometres, the James Webb and Hubble images “come closer”.

A burst of blue light flashing through space.
Three images of the DART collision taken by NASA’s Hubble Space Telescope have been combined. (NASA, ESA, Jian-Yang Li (PSI); Alyssa Pagan (STScI))

Fitzsimmons told AFP that James Webb and Hubble “can offer a view of asteroids from just a few kilometers away, and you can really see clearly how material is blown away by the explosive impact of DART”.

“It’s really quite spectacular,” he said.

An image taken four hours after the impact by James Webb’s Near Infrared Camera (NIRCam) “shows what appears to be plume-like material moving away from the center of the impact,” according to a joint statement from the European Space Agency. Webb and Hubble.

Hubble images taken 22 minutes, five hours and eight hours after impact show the expanding spray of matter from the DART impact site.

“I’m worried there’s nothing left”

The European Space Agency’s Ian Carnelli said the “really impressive” Webb and Hubble images were remarkably similar to those taken by LICIACube, the toaster-sized satellite, just 50 kilometers from the asteroid after it left the DART spacecraft a few weeks ago. .

Carnelli, manager of ESA’s Hera mission, which intends to inspect the damage in four years, said the images depict an impact that appears to be “much larger than we expected.”

At first, “I was very worried that there was nothing left of Dimorphos,” Carnelli told AFP.

The Hera mission, scheduled to launch in October 2024 and reach the asteroid in 2026, was expected to study a crater about 10 meters (33 feet) in diameter.

Now it looks like it’s going to be bigger, Carnelli said, “if there’s a crater at all, maybe a piece of Dimorphos just broke off.”

The true measure of DART’s success will be how well it skews the asteroid’s trajectory, so the world can start preparing to defend against larger asteroids that may come our way in the future.

Carnelli said it will probably take at least a week for Earth-bound telescopes and radars to get a first estimate of how much the asteroid’s orbit has changed, and three to four weeks before an accurate measurement can be made.

‘Big Effects’

“I expect a bigger deviation than what we planned,” he said.

This “will have huge implications in planetary defense because it means this technique can be used for larger asteroids,” Carnelli added.

“Until now, we thought the only warping technique would be to send a nuclear device.”

Even if no material is “ejected” from Dimorphos, DART will still have some impact on its orbit, Fitzsimmons said.

A red flickering explosion in space.
Timelapse of the DART collision captured by Webb. (NASA, ESA, CSA, Cristina Thomas (Northern Arizona University), Ian Wong (NASA-GSFC); Joseph DePasquale (STScI))

“But the more material and the faster it moves, the more deflection there will be,” he said.

Observations by James Webb and Hubble will help reveal how much and how quickly material is ejected from the asteroid, as well as the nature of its surface.

The asteroid impact marked the first time two space telescopes had observed the same celestial body.

Since launching in December and releasing its first images in July, the James Webb Hubble has taken the title of the most powerful space telescope.

Fitzsimmons said the images are “a wonderful demonstration of the additional science you can get from using multiple telescopes at the same time.”

© Agence France-Presse

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