A NASA spacecraft is ready to collide with an asteroid to change its path – 09/23/2022 at 07:26

Illustration provided on November 4, 2021 by NASA of the DART spacecraft that had to crash into the asteroid Dimorphos to slightly deviate its trajectory (NASA / Handout)

Dinosaurs sure like to think that. Science fiction movies, like “Armageddon” or more recently “Don’t Look: Cosmic Denial”, have been thinking about this for a long time.

This time, NASA will finally try what has never been done before: deflecting the trajectory of an asteroid by projecting a kamikaze ship at it. An attempt at “planetary defense”, which should make it possible to better protect humanity against possible threats in the future.

The Dart mission (dart, in English) started last November from California. After ten months of travel, the spacecraft should hit the asteroid Dimorphos at 23:14 GMT Monday, at a speed of more than 20,000 km / h.

The ship is no bigger than a car, and its target is about 160 meters in diameter (half the height of the Eiffel Tower).

Do not be afraid, Dimorphos does not represent a threat to the Earth in any way: its orbit around the Sun passes only seven million kilometers from us at its closest.

But the mission “is important to achieve before we discover the real need,” said Andrea Riley, who manages NASA’s mission.

The moment of impact promises to be extraordinary and can be followed live on the video channel of the American agency.

It’s not a question of destroying the asteroid but of pushing it a little further. The technique is called kinetic impact.

Dimorphos is the satellite of a larger asteroid, Didymos (780 meters in diameter), which it orbits in 11 hours and 55 minutes. The goal is to reduce Dimorphos’ orbit around Didymos by about ten minutes.

This change can be measured by telescopes from Earth, by observing the change in brightness when a small asteroid passes in front of a large one.

The goal may seem modest but this performance is important for the future.

The goal is to better understand how Dimorphos reacts, which is representative of a population of common asteroids, whose exact composition is unknown. The effect of the effect will depend a lot on its porosity, ie if it is more or less compact.

– One frame per second –

To hit such a small target, the ship will drive autonomously for the last four hours, like a self-guided missile.

His camera, called Draco, will take the first pictures of the asteroid at the last moment, its shape is still unknown (round, oblong, etc.). At a rate of one frame per second, it appears live on Earth with a delay of only about 45 seconds.

A graphic showing the impact of NASA's Dart mission on the orbit of asteroid Dimorphos (AFP/Jim WATSON)

A graphic showing the impact of NASA’s Dart mission on the orbit of asteroid Dimorphos (AFP/Jim WATSON)

“It starts as a small point of light, until it fills the entire frame,” said Nancy Chabot, of the Applied Physics Laboratory (APL) at Johns Hopkins University, where the control center is located.

“These images will keep coming, until they don’t,” he added, referring to the moment of the explosion.

Three minutes later, a shoebox-like satellite, called LICIACube and released by the craft a few days ago, will pass about 55 km from the asteroid to take images of the ejecta. They will be sent back to Earth in the following weeks and months.

The event will also be observed by the Hubble and James Webb space telescopes, which should detect a bright dust cloud.

Then, the European Hera probe, which should fly in 2024, will closely observe Dimorphos in 2026 to assess the consequences of the impact and calculate, for the first time, the mass of the asteroid.

– Find them all –

Few of the known asteroids are considered potentially dangerous, and none will be in the next 100 years.

But “I guarantee that if you wait long enough, something will happen,” said NASA chief scientist Thomas Zurbuchen.

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). About 3,000 new ones are discovered every year.

NASA's DART Mission Control Center at Johns Hopkins University's Applied Physics Laboratory (APL) in Maryland on September 12, 2022 (AFP/Jim WATSON)

NASA’s DART Mission Control Center at Johns Hopkins University’s Applied Physics Laboratory (APL) in Maryland on September 12, 2022 (AFP/Jim WATSON)

Those of a kilometer or more were almost all found, according to scientists. But they estimate that only about 40% of the asteroids they know measure 140 meters or more — ones capable of destroying entire regions.

If Dart misses its target, the ship should have enough fuel for another test in two years.

And if the mission succeeds, it will be a first step toward a real defense capability, according to Nancy Chabot. “Earth has been hit by asteroids for billions of years, and it will happen again. As humans, let’s make sure we live in a civilization where we can avoid it.”

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