The James Webb and Hubble telescopes on Thursday revealed their first images
of a spacecraft deliberately smashing into an asteroid, as astronomers
indicated that the impact looks to have been much greater than expected.
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The world's telescopes turned their gaze towards the space rock Dimorphos
earlier this week for a historic test of Earth's ability to defend itself
against a potential life-threatening asteroid in the future.
Astronomers rejoiced as
NASA's Double Asteroid Redirection Test (DART)
impactor slammed into its pyramid-sized, rugby ball-shaped target 11 million
kilometres (6.8 million miles) from Earth on Monday night.
Images taken by Earth-bound telescopes showed a vast cloud of dust expanding
out of Dimorphos -- and its big brother Didymos which it orbits -- after the
spaceship hit.
While those images showed matter spraying out over thousands of kilometres,
the James Webb and Hubble images "zoom in much closer", said Alan
Fitzsimmons, an astronomer at Queen's University Belfast involved in
observations with the ATLAS project.
James Webb and Hubble can offer a view "within just a few kilometres of
the asteroids and you can really clearly see how the material is flying out
from that explosive impact by DART", Fitzsimmons told AFP.
"It really is quite spectacular," he said.
An image taken by James Webb's Near-Infrared Camera (NIRCam) four hours
after impact shows "plumes of material appearing as wisps streaming away
from the centre of where the impact took place", according to a joint
statement from the European Space Agency, James Webb and Hubble.
Hubble images from 22 minutes, five hours and eight hours after impact show
the expanding spray of matter from where DART hit.
- 'Worried there
was nothing left' -
Ian Carnelli of the European Space Agency said that the "really
impressive" Webb and Hubble images were remarkably similar to those taken
by the toaster-sized satellite LICIACube, which was just 50 kilometres from the
asteroid after separating from the DART spacecraft a few weeks ago.
The images depict an impact that looks "a lot bigger than we
expected," said Carnelli, the manager of the ESA's Hera mission which
intends to inspect the damage in four years.
"I was really worried there was nothing left of Dimorphos" at
first, Carnelli told AFP.
The Hera mission, which is scheduled to launch in October 2024 and arrive at
the asteroid in 2026, had expected to survey a crater around 10 metres (33
feet) in diameter.
It now looks like it will be far bigger, Carnelli said, "if there is a
crater at all, maybe a piece of Dimorphos was just chunked off."
The true measure of DART's success will be exactly how much it diverted the
asteroid's trajectory, so the world can start preparing to defend itself
against bigger asteroids that could head our way in the future.
It will likely take Earth-bound telescopes and radars at least a week for a
first estimate of how much the asteroid's orbit has been altered, and three or
four weeks before there is a precise measurement, Carnelli said.
- 'Huge
implications' -
"I am expecting a much bigger deflection than we had planned," he
said.
That would have "huge implications in planetary defence because it means
that this technique could be used for much larger asteroids", Carnelli
added.
"Until today, we thought that the only deflection technique would be to
send a nuclear device."
Fitzsimmons said that even if no material had been "flung off"
Dimorphos, DART still would still have slightly affected its orbit.
"But the more material and the faster it's moving, the more of a
deflection there will have been," he said.
The observations from James Webb and Hubble will help reveal how much -- and
how quickly -- matter sprayed from the asteroid, as well as the nature of its
surface.
The asteroid impact marked the first time the two space telescopes observed
the same celestial body.
Since launching in December and releasing its first images in July, James
Webb has taken the title of most powerful space telescope from Hubble.
Fitzsimmons said the images were "a beautiful demonstration of the
extra science you can get by using more than one telescope
simultaneously".
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