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Deviated asteroid “Armageddon style”: telescopes offer new images

It will take several weeks to find out if NASA’s “Armageddon” mission worked, but the images are already there.

The James Webb and Hubble telescopes, the most powerful space observatories, revealed detailed views of the impact of NASA’s Dart spacecraft on an asteroid on Thursday, images that will help scientists understand the expected orbit-altering process.

It is the first time that the two famous space telescopes have been used to simultaneously observe the same celestial object: an asteroid located 11 million kilometers from Earth, the target of the world’s first planetary defense test.

A cloud of several thousand kilometers

On Monday evening, NASA’s Dart spacecraft deliberately crashed into the surface of Dimorphos, a small moon 160 meters in diameter orbiting a larger asteroid, in an attempt to deflect its orbit.

It will take a few days to a few weeks before scientists can confirm that its trajectory has indeed been altered. And manage to locate it in relation to its original position.

But soon after the collision, early images – taken by ground-based telescopes and the onboard LICIACube nano-satellite – showed a vast cloud of dust around Dimorphos, stretching for thousands of kilometres.

A cloud on which the James Webb and Hubble telescopes, operating in space, were able to “zoom in more finely”, Alan Fitzsimmons, an astronomer at Queen’s University in Belfast, involved in the ground observations of the project, told AFP. ATLAS, a network of four telescopes operated from Hawaii.

These images allow us to see “clearly how this material is shattered after the explosive impact of Dart, it’s quite spectacular”, he says.

A whole piece of asteroid torn off?

The impact seems much greater than expected”comments for his part Ian Carnelli, head of the European Hera mission which will inspect the damage to the surface of Dimorphos in four years.

Hera had counted on a crater about 10 meters in diameter, but in view of the images taken by LICIACube 50 km from the star, confirmed by those of space telescopes, it could be much larger… ” if crater there is , because maybe a whole piece of Dimorphos was just ripped out”.

The James Webb’s NIRCam camera, working in the near infrared, observed the impact for several hours after the collision. Its ten images reveal a compact core surrounded by ‘plumes of material’ similar to expanding filaments, ‘moving away from the center of where the impact took place’, describes a joint statement from the European Space Agency. (ESA), Webb and Hubble.

Images from the Hubble telescope, taken by a wide-angle camera 22 minutes, 5 hours and 8 hours after the crash, show in visible light the movement of ejecta – the material torn from the star.

These appear as rays, with a gradual increase in brightness, but which stabilized eight hours after impact, which “puzzles astronomers”, according to the press release.

The James Webb telescope, which has been observing 1.5 million kilometers from Earth since last July, and Hubble, in service for more than 30 years, will soon reveal how much material has been ejected, its nature (large pieces or fine dust?) and at what speed.

This information will help scientists to “understand how effectively a kinetic impact can alter an asteroid’s orbit”, according to the press release. The kinetic impact technique experimented by NASA consists of colliding with an asteroid in order to “push” it slightly, and thus deviate its trajectory. A bit like playing pool in space.

The more material ejected, the more the trajectory has a chance of being altered. “How quickly astronomers can measure the deviation will depend on how efficient Dart is.”emphasizes Alan Fitzsimmons.