Monday, January 17

Space. Planetary defense: how Europe will help NASA deflect asteroids

Next fall, a NASA spacecraft is expected to crash into Dimorphos, an asteroid eleven million kilometers from Earth. No worries: this is the raison d’être of the DART (Double Asteroid Redirection Test, or “dart”) spacecraft, which was sent this Wednesday morning into space from a SpaceX Falcon 9 rocket.

By hitting Dimorphos, the ship will allow scientists to strengthen our planetary defense. Clearly, the way to avoid an asteroid falling on our head. This is the very first time that this so-called kinetic impact technique will be tested.

To put it simply, in ten months or so, the DART mission ship should in theory hit Dimorphos at 24,000 km / h (6km / s), which is a moon orbiting a larger asteroid, named him Didymos. . The impact should then reduce Dimorphos’ orbit.

Hera backing up DART

This asteroid is not a threat to our planet. But if it is, the DART mission could change its course and thus save thousands or even millions of lives. Provided, of course, that the ship crashes on the asteroid and deflects it enough.

To find out if the NASA mission worked, a small satellite named LICIACube and developed by the Italian Space Agency will be released by the main spacecraft ten days before the collision. Three minutes after the telescoping, it will fly over Dimorphos, in order to observe the effect of the shock and, with a little luck, the crater on the surface. Telescopes will then make it possible to observe the change in trajectory from Earth.

But that’s not all. In 2024, the European Space Agency (ESA) will send its own probe near Dimorphos. Baptized Hera, after the Greek goddess of marriage, it will not arrive at its destination until 2026.

From test to method

The Hera probe will make it possible to “measure the impact of the crater, the effective deviation and all the properties of the asteroid,” Patrick Michel told France Inter this Wednesday morning. “Hera will have the delicate task of carrying out a detailed post-impact study in order to transform this large-scale experiment into a controlled and reproducible asteroid deflection technique”, details ESA on its site.

In other words, it “will make it possible to carry out simulations which can be applied to other scenarios”, summarizes Patrick Michel. But ESA’s mission will have a bunch of other scientific implications. It will first allow “the demonstration of several new technologies, such as autonomous navigation around the asteroid,” said ESA.

Asteroids are the remnants of the bricks that formed our planets.

Patrick Michel, main instigator of the Hera mission, on France Inter

Hera will also offer a better understanding of the internal structure, composition and precise mass of Dimorphos, allowing us to understand how binary asteroids are formed, which make up 15% of all known asteroids. Which is not nothing, as Patrick Michel explained on the radio: “Asteroids are the remains of the bricks that formed our planets. By going to observe them we go back in time, since they are the best tracers in history. of the Solar System “.

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