ESA's Hera Mission

Hera – named after the Greek goddess of marriage – will be, along with NASA's DART spacecraft, humankind’s first probe to rendezvous with a binary asteroid system, a little understood class making up around 15% of all known asteroids.

Hera is the European contribution to an international double-spacecraft collaboration. NASA will first perform a kinetic impact on the smaller of the two bodies, then Hera will follow-up with a detailed post-impact survey that will turn this grand-scale experiment into a well-understood and repeatable planetary defence technique.

While doing so, Hera will also demonstrate multiple novel technologies, such as autonomous navigation around the asteroid – like modern driverless cars on Earth, and gather crucial scientific data, to help scientists and future mission planners better understand asteroid compositions and structures.

Due to launch in 2024, Hera would travel to a binary asteroid system – the Didymos pair of near-Earth asteroids. The 780 m-diameter mountain-sized main body is orbited by a 160 m moon, formally christened 'Dimorphos' in June 2020, about the same size as the Great Pyramid of Giza.

This smaller body is Hera’s focus: the spacecraft would perform high-resolution visual, laser and radio science mapping of the moon, which will be the smallest asteroid visited so far, to build detailed maps of its surface and interior structure.

By the time Hera reaches Didymos, in 2026, Dimorphos will have achieved historic significance: the first object in the Solar System to have its orbit shifted by human effort in a measurable way.