Space: target achieved for Dart, the NASA spacecraft crashed into an asteroid

Cheers exploded in the control room in Maryland, USA. NASA’s impactor crashed into an asteroid Monday in an attempt to deflect its trajectory. This unprecedented test mission was to allow humanity to learn how to protect itself from a potential future threat.

The craft, which is smaller than a car, sped at a speed of more than 20,000 km/h on its target, reaching it at the scheduled time (23:14 GMT or 1:14 Brussels time).

A few minutes before, the asteroid Dimorphos, located about 11 million kilometers from Earth, has gradually grown in the spectacular images transmitted live by the ship. We could clearly make out the pebbles on its gray surface just before the images stop at the moment of explosion.

We have entered a new era where we potentially have the ability to protect ourselves from a dangerous asteroid impact“, 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 the satellite of a larger asteroid, Didymos, which it has so far orbited in 11 hours and 55 minutes. NASA is looking to reduce Dimorphos’ orbit 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 orbit has indeed changed. They will do this thanks to telescopes on Earth, which will observe the variation in brightness as the small asteroid passes in front of and behind the large one.

If the goal remains modest compared to the disaster scenarios of science fiction movies like “Armageddon,” this “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.

“I think the earthlings can now sleep easy, I will,” said Elena Adams, an engineer on the mission.

carefully examined

The ship had been traveling for ten months since starting in California.

To hit a target as small as Dimorphos, the final stage of flight was fully automatic, like a self-guided missile.

Three minutes after impact, a shoebox-sized satellite called LICIACube and released by the Upriver spacecraft was expected to pass about 55 km from the asteroid to take pictures of the ejecta.

The event was also to be observed by the Hubble and James Webb space telescopes, which should be able to detect a luminous dust cloud and thus help to assess the amount of material ejected.

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.

The European Hera probe, due to take off in 2024, will also closely observe Dimorphos in 2026 to assess the consequences of the impact and calculate the asteroid’s mass for the first time.


Asteroids have held surprises for scientists in the past. In 2020, the American probe Osiris-Rex had sunk much more than expected into the surface of the asteroid Bennu. Likewise, the composition of Dimorphos is not currently known.

If the asteroid reacts to the Dart impact in a completely unexpected way, it might actually make us rethink how kinetic impact is a generalizable technique.“, Tom Statler, chief scientist for the mission, warned last week.

66 million years ago, the dinosaurs disappeared after the collision of an approximately 10 kilometer asteroid with the Earth.

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’re not all listed yet.

Those of a kilometer or more have almost all been seen, according to the researchers. But they estimate that they only know about 40% of asteroids that measure 140 meters or more—those capable of destroying an entire region.

Our most important task is to find“The missing ones,” said Lindley Johnson, planetary defense officer at NASA. The earlier they are discovered, the more time experts will have to introduce a means to defend against them.

The Dart mission is a crucial first step in this direction, according to Mr Johnson: “It is a very exciting period (…) for the history of space, and even the history of humanity.”

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