NASA diverts an asteroid from its path

NASA announced Tuesday that it had deflected an asteroid from its orbit in an unprecedented “planetary defense” mission.

“It’s not Hollywood”, but NASA: The US space agency announced on Tuesday that it succeeded in diverting an asteroid from its orbit by throwing a spacecraft the size of a refrigerator towards its surface in late September during an unprecedented test mission , which will allow humanity to learn to protect itself against a possible future threat.

The Dart mission vehicle had deliberately rammed into its target, the asteroid Dimorphos, which is the satellite of a larger asteroid named Didymos. The NASA device managed to move it by reducing its orbit by 32 minutes, the head of the space agency, Bill Nelson, said during a press conference. This is “a watershed moment for planetary defense and a watershed moment for humanity,” he said.

It would already have been “considered a huge success if it (the craft) had only reduced the orbit by about 10 minutes”. “But he actually reduced it by 32 minutes,” Nelson added. With this mission, “we have proven that we are serious as defenders of the planet”, he said.

Dimorphos, located about 11 million kilometers from Earth at the time of impact, is about 160 meters in diameter and poses no danger to our planet. It has so far orbited Didymos in 11 hours and 55 minutes, a period shortened to 11 hours and 23 minutes, Nelson said. “It looks like a movie script, but it’s not Hollywood.” “This mission shows that NASA is trying to be ready for whatever the universe throws at us,” he said.

If the goal remained relatively modest compared to the disaster scenarios of science fiction films like “Armageddon”, this unprecedented “planetary defense” mission, named Dart (dart, in English), is the first to test such a technique. It allows NASA to train if an asteroid threatens to hit Earth one day.

egg shape

To confirm that the asteroid’s orbit had indeed changed, it was necessary to wait for scientists to analyze data from telescopes on the ground. The latter observed the variation in brightness when the small asteroid passes in front of and behind the large one. Shortly after the collision, early images – taken by ground-based telescopes and the onboard nano-satellite of the LICIACube mission – showed a huge cloud of dust around Dimorphos, stretching for thousands of kilometres. Then the James Webb and Hubble telescopes, the most powerful space observatories, revealed detailed views of the impact of NASA’s spacecraft, showing in particular the movement of the ejecta, the material torn from the star. All this should make it possible to better understand the composition of Dimorphos, which is representative of a population of fairly common asteroids, and therefore to measure the exact effect that this technique – called kinetic impact – can have on them.

Images of Dimorphos, taken shortly before the impact, show the surface to be gray and rocky and egg-shaped. Knowing these details is important if humanity is ever forced to crash into an object approaching Earth. The ship had been traveling for ten months since starting in California.

Almost 30,000 asteroids of all sizes have been cataloged in the vicinity of the Earth (they are called near-Earth objects, that is, their orbit crosses that of our planet). Today, none of these known asteroids threaten our planet for the next 100 years. Except they haven’t all been identified yet. Those of a kilometer or more have almost all been seen, according to the researchers. But they believe they only know about 40% of the asteroids measuring 140 meters or more, the ones capable of destroying an entire region.

With AFP/Issam Ahmed

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