This image provided by NASA on October 11, 2022 shows the asteroid Dimorphos as seen by the DART spacecraft eleven seconds before impact. HANDOUT / AFP
The US space agency managed to deflect an asteroid from its orbit by launching a spacecraft onto its surface during an unprecedented test mission at the end of September, which should allow humanity to learn how to protect itself from a possible future threat, announced NASA on Tuesday, October 11th.
Just arrived: It has been confirmed that the #DARTmission impact has changed the orbit of the moon Dimorphos around its asteroid… https://t.co/EQxQ2sfteo
The DART (for Double Asteroid Redirection Test) spacecraft intentionally crashed into its target, the asteroid Dimorphos, which is the satellite of a larger asteroid called Didymos. The NASA device managed to move it and shorten its orbit by 32 minutes, Space Agency chief Bill Nelson announced during a news conference, hailing “a pivotal moment for the defense of the planet and a pivotal moment for the planet.” Mankind”.
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An unprecedented “Planet Defense” mission
It would have already been “considered a huge success [si le vaisseau] had only shortened the orbit by about 10 minutes, but actually shortened it by 32 minutes,” he added. With this mission, “NASA has proven that we mean business as defenders of the planet,” he said. The ship had been ten months since its launch in California.
The asteroid Dimorphos, which was about 11 million kilometers from Earth at the time of impact, is about 160 meters in diameter. It poses no threat to our planet. While the purpose of the maneuver is relatively modest compared to the catastrophic scenarios of sci-fi movies like Armageddon, this unprecedented “planet defense” mission dubbed DART (Dart means “dart” in English) the first to try such a technique. It allows NASA to train for the day when an asteroid threatens to hit Earth.
To confirm that the asteroid’s trajectory was altered, scientists had to analyze data from ground-based telescopes. The latter observed the variation in brightness as the small asteroid passes in front of and behind the large one.
Shortly after the collision, initial images – taken by ground-based telescopes and the mission’s onboard LICIACube nanosatellite – revealed a huge dust cloud surrounding Dimorphos, stretching thousands of kilometers.
Then the James Webb and Hubble telescopes, the most powerful space observatories, showed detailed views of NASA’s spacecraft impact, showing, among other things, the movement of ejecta, the material torn away from the star.
Almost 30,000 asteroids near Earth
All of this should make it possible to better understand the composition of Dimorphos, representative of a population of fairly common asteroids, and therefore to measure the precise effect that this technique, dubbed “kinetic impact”, can have on them.
Images of Dimorphos taken just before impact show that its surface is gray, rocky, and ovoid.
Nearly 30,000 asteroids of all sizes have been cataloged near Earth: they are called near-Earth planets, meaning their orbits intersect that of our planet. Today, none of these known asteroids threaten our planet for the next hundred years, but all have not yet been counted: scientists estimate that they only know 40% of asteroids 140 meters in size or larger – those capable of to devastate an entire region.