Hera prepares for launch, on a mission to protect Earth and solve asteroid mysteries

Hera will be launched into space using a SpaceX Falcon 9 rocket. Credit: ESA-Science Office.

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07 October 2024

If an asteroid were to collide with Earth, the damage would be devastating for the planet and all living things. To prevent this, one possible solution is to act early — long before the asteroid gets close — by sending a probe to smash into it, nudging it off course and preventing a direct hit with Earth. It sounds like a cosmic game of billiards, but would this really work? Scientists have been conducting an exciting experiment to find out!

This picture made by an artist shows Hera nearing Dimorphos, two years from now. Credit: ESA-Science Office.

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In September 2022, NASA performed the first-ever asteroid deflection test. A probe called DART intentionally crashed into Dimorphos, a small asteroid that orbits a larger one named Didymos, to change its orbit. But how effective was the mission? And could this method be used in the future to prevent an asteroid from hitting Earth? To fully understand the results, scientists need another probe: Hera.

Hera is ESA’s first planetary defence mission, set to launch in October 2024. After a two-year journey, Hera will reach Didymos and Dimorphos to gather important close-up data. The goal is to measure how much Dimorphos’ orbit shifted after DART’s impact, and work out if this technique can reliably protect Earth from future asteroid threats.

See how big Dimorphos and Didymos are. Credit: ESA-Science Office.

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Hera is equipped with high-tech equipment designed for this crucial mission. Perhaps most excitingly, it will carry two mini-satellites, each the size of a shoebox, called Juventas and Milani. Once Hera is near Dimorphos, these satellites will detach to collect extra data. If all goes according to plan, they will even land on the asteroid’s surface!

Hera will also conduct the most detailed study ever of a binary asteroid system — two asteroids orbiting each other. Binary systems make up about 15% of all known asteroids, yet scientists know little about them. The information Hera discovers could help to solve asteroid mysteries!

With the right technology, we may soon prove that not only can we explore space, but also protect ourselves from its dangers! Do you think that knocking asteroids off course is a good way of protecting Earth? Can you think of any other methods?

Cool fact: Dimorphos is roughly the size of the Great Pyramid of Giza in Egypt, while Didymos is as big as a mountain!

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