A Nasa spacecraft crashes into an asteroid at 23,000 km/h, in a dramatic first test of deflection technology that could in the future alter the trajectory of an incoming space rock to prevent a collision cataclysmic with the Earth.
As the 600 kg dart projectile Closing in on its target, Dimorphos, early Tuesday UK time, its camera sent back a series of spectacular images – one per second – until individual rocks, boulders and smooth ground became visible at the surface of the peanut-shaped asteroid.
Then came the moment of impact, right on target, and the stream of images stopped. scientists and engineers from mission headquarters at Johns Hopkins University’s Applied Physics Laboratory in the United States erupted with the cheers and applause, hugs and handshakes that traditionally greet a successful space mission.
“We are now entering a new era for humanity – an era in which we potentially have the ability to protect ourselves from a dangerous asteroid impact,” Lori Glaze, director of planetary sciences at NASA, said immediately after. the impact.
“Now is where the science really begins,” Glaze added. “Now that we have had an impact, we will see how effective we have been [at deflecting the asteroid].”
Artist’s impression of Dart approaching Dimorphos before impact © via REUTERS
The collision was observed by LiciaCube, a small Italian-made satellite that had accompanied Dart on its journey to Dimorphos 11 minutes from Earth. It separated from its parent spacecraft 15 days ago and flew past the asteroid minutes after impact, at a safe distance of 55 km.
LiciaCube will take longer to transmit its images to Earth for scientific analysis. They are expected to show not only the impact site, but also the resulting cloud of dust and gas, giving Dimorphos a temporary tail like a miniature comet.
But ground-based telescopes will primarily assess the effects of the collision over the next few weeks. The asteroid, which measures around 160 meters in diameter, is too far from Earth for them to glean detailed images, but they will be able to see the initial dust plume and later assess how far the impact moved its trajectory in space.
NASA chose this target because it is part of an unusual double asteroid. Dimorphos moves like a moon around a larger partner called Didymos – and a deviation from this local orbit is much easier to detect than a change in orbit around the sun.
Dimorphos takes around 11 hours to cover Didymos. Advanced calculations suggest that the impact will reduce this time by 10 to 15 minutes.
A NASA-issued space map of the asteroid Didymos and its orbiting moon Dimorphos © PA
The actual decrease in its orbital time will provide key information about the asteroid’s texture – hard or soft, consolidated or crumbly.
According to astronomers, there is no chance that the impact could push the asteroid on a trajectory that threatens Earth.
In 2024, the European Space Agency will launch a probe called Hera to perform a detailed post-impact survey of the binary asteroid system in 2026.
The Dart mission is humanity’s first attempt to alter the trajectory of a natural object in space. “We’ve all seen it in movies like Armageddonbut the real stakes are high,” said NASA Administrator Bill Nelson.
Surveys from space have convinced astronomers that there is no risk in the next few centuries of Earth encountering something as big as the 10km-wide asteroid that struck 66 years ago. minutes and ended the dinosaurs. But there are thousands of smaller “Near-Earth Objects” that are still unexplored and capable of devastating large areas of the planet.