“Planetary Defense”: NASA targets an asteroid during a space collision | Space News

After NASA deliberately crashes a car-sized spacecraft into an asteroid next week, it will be up to the European Space Agency’s Hera mission to investigate the “crime scene” and uncover the secrets of these potentially devastating space rocks.

NASA’s Double Asteroid Redirection Test (DART) is aiming to collide with the moonlet asteroid Dimorphos on Monday evening, hoping to alter its trajectory slightly – the first time such an operation has been attempted.

While Dimorphos is 11 million kilometers (6.8 million miles) away and poses no threat to Earth, the mission is a test run in case the world ever needs to deflect an asteroid heading our way.

Astronomers around the world will observe the DART impact and its effects will be closely monitored to see if the mission passed the test.

The European Space Agency’s Hera mission, named after the ancient Greek queen of the gods, will follow in her footsteps.

The Hera spacecraft is scheduled to launch in October 2024, with the aim of arriving at Dimorphos in 2026 to measure the exact impact DART had on the asteroid.

Scientists are not only excited to see DART’s crater, but also to explore an object that is quite out of this world.

‘A new world’

Dimorphos, which orbits larger asteroid Didymos as they hurtle through space together, not only provides “a perfect testing opportunity for a planetary defense experiment, but it’s also a completely new environment” , said Ian Carnelli, head of the Hera mission.

Hera will be loaded with cameras, spectrometers, radars and even toaster-sized nano-satellites to measure the asteroid’s shape, mass, chemical composition and more.

NASA’s Bhavya Lal said understanding the size and composition of these asteroids is extremely important.

“If an asteroid is made up of, say, loose gravel, the approaches to disrupting it may be different than if it were metal or another type of rock,” she told Congress. Astronautics International in Paris this week.

So little is known about Dimorphos that scientists will discover “a new world” along with the public on Monday, said Patrick Michel, principal investigator of the Hera mission.

“Asteroids aren’t boring space rocks — they’re super exciting because they have a huge diversity” in size, shape and composition, Michel said.

Because they have low gravity compared to Earth, matter could behave completely differently than expected. “Unless you touch the surface, you can’t know the mechanical response,” he said.

“Behaved almost like a liquid”

For example, when a Japanese probe dropped a small explosive near the surface of asteroid Ryugu in 2019, it was expected to crater two to three meters. Instead, he dug a 50-meter hole.

“There was no resistance,” Michel said. “The surface behaved almost like a fluid [rather than solid rock]. How weird is that? »

One of the ways the Hera mission will test Dimorphos will be to land a nano-satellite on its surface, in part to see how well it bounces.

Binary systems such as Dimorphos and Didymos make up about 15% of known asteroids, but have yet to be explored.

With a diameter of just 160 meters – about the size of the Great Pyramid of Giza – Dimorphos will also be the smallest asteroid ever studied.

Knowing about DART’s impact is not just important for planetary defense, Michel said, but also for understanding the history of our solar system, where most cosmic bodies formed through collisions and are now riddled with craters.

This is where DART and Hera could illuminate not only the future but also the past.

This computer generated image shows the impact of the DART projectile on the asteroid binary system Didymos [European Space Agency via AFP]

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