The James Webb and Hubble telescopes on Thursday showed their first images of a spacecraft intentionally slamming into an asteroid, as astronomers say the impact appears to have been much larger than expected.
The world’s telescopes turned their gaze to the space rock Dimorphos earlier this week in a historic test of Earth’s ability to defend itself against a potentially life-threatening asteroid in the future.
Astronomers rejoiced 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 on Monday night.
Images taken by ground-based telescopes showed a huge cloud of dust spreading from Dimorphos – and its big brother Didymos, which it orbits – after the spacecraft’s impact.
While these images showed matter spraying thousands of kilometers away, “the James Webb and Hubble images zoom in much closer,” said Alan Fitzsimmons, an astronomer at Queen’s University Belfast who has been involved in observations with the ATLAS project.
James Webb and Hubble can provide a view “just a few miles from the asteroids and you can really clearly see the material flying out of that explosive impact from DART,” Fitzsimmons told AFP.
“It’s really quite spectacular,” he said.
An image taken four hours after the impact by James Webb’s near-infrared camera (NIRCam) shows “clouds of material appearing as wisps streaming away from the center of the impact,” according to a joint statement from the European Space Agency. Webb and Hubble.
Hubble images from 22 minutes, five hours and eight hours after impact show the expanding nebula of matter from where DART impacted.
– ‘Worried there was nothing left’ –
The European Space Agency’s Ian Carnelli said the “really stunning” Webb and Hubble images are remarkably similar to those taken by the toaster-sized LICIACube satellite, which was just 50 kilometers from the asteroid, after separating from the DART spacecraft a few weeks ago had separated .
The images show an impact that “looks a lot bigger than we expected,” said Carnelli, the manager of ESA’s Hera mission, which intends to inspect the damage in four years.
“I was really concerned 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, had expected to probe a crater about 10 meters (33 feet) in diameter.
It now looks like it will be much larger, Carnelli said, “if there’s a crater at all, maybe just a piece of Dimorphos was knocked off.”
The true measure of DART’s success will be exactly how much it deflected the asteroid’s trajectory so the world can prepare to defend itself against larger asteroids that may be heading our way in the future.
It will likely be at least a week before ground-based telescopes and radars make an initial estimate of how much the asteroid’s orbit has been altered, and three or four weeks before there’s an accurate reading, Carnelli said.
– “Huge Impact” –
“I expect a much larger deviation than we had planned,” he said.
That would have “huge implications for planetary defenses because it means this technique could be used on much larger asteroids,” Carnelli added.
“Until now, we thought the only diversionary technique was to send in a nuclear device.”
Fitzsimmons said that even if no material had been “ejected” from Dimorphos, DART would still have slightly affected its orbit.
“But the more material and the faster it’s moving, the more distraction there will have been,” he said.
James Webb and Hubble’s observations will help reveal how much – and how fast – matter is being sprayed from the asteroid, as well as the nature of its surface.
The asteroid impact was the first time the two space telescopes observed the same celestial body.
Since launching in December and releasing the first images in July, James Webb has taken the title of Hubble’s most powerful space telescope.
Fitzsimmons said the images are “a nice demonstration of the extra science you can get from using more than one telescope at a time.”
