After asteroid collision, Europa’s Hera will investigate the “crime scene”.

After NASA deliberately smashed 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) aims to collide with the asteroid moon Dimorphos on Monday night in hopes of slightly altering its trajectory — 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 someday needs to deflect an asteroid from its path.

Astronomers around the world will be watching the effects of DART and closely tracking its impact to see if the mission passed the test.

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

The Hera spacecraft is scheduled for launch in October 2024 and is scheduled to arrive at Dimorphos in 2026 to measure the precise impact of DART on the asteroid.

But scientists are not only excited to see DART’s crater, but also to study an out-of-this-world object.

‘A New World’

Dimorphos, orbiting a larger asteroid Didymos as they hurtle through space together, not only provides a “perfect test opportunity for a planetary defense experiment, but also a whole new environment,” said ESA’s Hera Mission Director Ian Carnelli.

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

NASA’s Bhavya Lal said understanding the size and composition of such asteroids is crucial.

“For example, if an asteroid is loose gravel, the approaches to disrupting it can be different than if it’s metal or some other type of rock,” she said at the International Astronautical Congress in Paris this week.

So little is known about Dimorphos that scientists will be discovering “a new world” at the same time as the public on Monday, said Hera mission lead investigator Patrick Michel.

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

And because they have low gravity compared to Earth, matter there could behave very differently than expected.

“Unless you touch the surface, you can’t know the mechanical response,” he said.

“Almost acted like a liquid”

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

“There was no resistance,” said Michel.

“The surface behaved almost like a liquid,” he added, and not like solid rock. “How weird is that?”

One way the Hera mission will test Dimorphos is by landing a nanosatellite on its surface, in part to see how hard it bounces.

Binary systems like Dimorphos and Didymos make up about 15 percent of known asteroids, but have not yet been explored.

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

Information about the effects of DART is important not only for planetary defense, Michel said, but also for understanding the history of our solar system, where most cosmic bodies were formed by collisions and are now riddled with craters.

Here, DART and Hera could not only shed light on the future, but also on the past.

© 2022 AFP