After asteroid collision, Europe's Hera will probe 'crime scene'

A NASA mission to deliberately smash a spacecraft into an asteroid blasts off on Monday

A NASA mission to deliberately smash a spacecraft into an asteroid blasts off on Monday

After NASA deliberately smashes 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 moonlet Dimorphos on Monday night, hoping to slightly alter its trajectory -- the first time such an operation has been attempted.

Astronomers around the world will watch DART's impact, and its effect will be closely followed to see if the mission passed the test.

The Hera spacecraft is planned to launch in October 2024, aiming to arrive at Dimorphos in 2026 to measure the exact impact DART had on the asteroid.

- 'A new world' -

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

"If an asteroid is made up of, for example, loose gravel, approaches to disrupt it may be different than if it was metal or some other kind of rock," she told the International Astronautical Congress in Paris this week.

"Asteroids are not boring space rocks -- they are super exciting because they have a great diversity" in size, shape and composition, Michel said.

"Unless you touch the surface, you cannot know the mechanical response," he said.

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

"The surface behaved almost like a fluid," rather than solid rock, he added. "How weird is that?" 

Binary systems like Dimorphos and Didymos represent around 15 percent of known asteroids, but have not yet been explored.

Learning about the impact of DART is not only important for planetary defence, Michel said, but also for understanding the history of our Solar System, where most cosmic bodies were formed through collisions and are now riddled with craters.

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