An asteroid intentionally hit a NASA spacecraft to divert it from its course. The Dart mission, scheduled last night, is proceeding as planned at 20,000 km/h. The footage of the collision is breathtaking.
Confirmed impact: a NASA spacecraft deliberately crashed into an asteroid on Monday to divert its path, during an unprecedented test mission that should allow humanity to learn how protect oneself from a potential threat in the future. The ship, which is smaller than a car, rushes at a speed of more than 20,000 km/h to its target, arriving on time. NASA teams, gathered at the mission control center in Maryland, in the United States, erupted in joy at the moment of the collision.
A few minutes before, the asteroid Dimorphos, located about 11 million kilometers from Earth, gradually grew in spectacular images broadcast live by the ship. We can clearly distinguish the pebbles on its gray surface, before the images stop at the moment of the explosion. “We are entering a new era, where we have the possibility to protect ourselves from the dangerous impact of the asteroid,” said Lori Glaze, director of planetary sciences at NASA.
Dimorphos is about 160 meters in diameter and poses no danger to our planet. It is actually a satellite of a larger asteroid, Didymos, that it is far circumnavigated in 11 hours and 55 minutes. NASA aims to reduce the orbit of Dimorphos by 10 minutes, that is, bring it closer to Didymos. It will take a few days to a few weeks before scientists can confirm that the asteroid’s path has indeed changed. They will do this thanks to telescopes on Earth, which will observe the difference in light as the small asteroid passes in front of and behind the large one.
Dart mission: “If a meteorite threatens our earth, we are ready to deflect it”, say Toulouse researchers
A “planetary defense” mission
If the goal remains modest compared to the disaster scenarios of science fiction films like “Armageddon”, this “planetary defense” mission, named Dart (dart, in English), is the first to test this technique. This allows NASA to train in case an asteroid threatens to hit Earth one day. “I think the Earthlings can sleep well, I do,” said Elena Adams, a mission engineer.
The ship has been traveling for ten months since it set sail in California. To hit a target as small as Dimorphos, the final flight phase is fully automatic, like a self-guided missile. Three minutes after the impact, a shoebox-like satellite, called LICIACube and released by the spacecraft over the river, is expected to pass about 55 km from the asteroid to take images of the ejecta. The event should also be observed by the Hubble and James Webb space telescopes, which should detect a bright cloud of dust and thus help evaluate the amount of material ejected. All this should make it possible to better understand the composition of Dimorphos, representative of a population of relatively common asteroids, and therefore to measure the exact effect that this technique – called kinetic effect – can have on them . The European Hera probe, which will fly in 2024, will also closely observe Dimorphos in 2026 to assess the consequences of the impact and calculate, for the first time, the mass of the asteroid.
30,000 asteroids have been identified in space
Asteroids have held surprises for scientists in the past. In 2020, the American probe Osiris-Rex sank further than expected on the surface of the asteroid Bennu. Likewise, the composition of Dimorphos is currently unknown. “If the asteroid responds to the Dart impact in an unexpected way, it may lead us to reconsider the extent to which the kinetic impact is a generalizable technique,” warns principal scientist Tom Statler last week. 66 million years ago, the dinosaurs disappeared after the collision of an asteroid about 10 kilometers wide with the Earth.
Nearly 30,000 asteroids of all sizes are listed around the Earth (they are called near-Earth objects, that is, their orbit crosses our planet). Today, none of these known asteroids threaten our planet in the next 100 years. Except they are not all listed yet. Those of a kilometer or more were almost all found, according to scientists. But they estimate that they only know about 40% of the asteroids measuring 140 meters and larger – those capable of destroying the entire region.
“Our most important job is to find” the missing, said NASA’s planetary defense officer Lindley Johnson. The earlier they are detected, the more time experts have to put in place a way to protect themselves against them. The Dart mission is an important first step in this direction, according to Mr Johnson: “This is a very exciting time (…) for the history of space, and even for the history of humanity.”