Planetary Defence Investigation
Hera is ESA's contribution to humanity's first full-scale planetary defence experiment. In September 2022, NASA's DART spacecraft deliberately crashed into Dimorphos, a 160-metre moonlet orbiting the larger asteroid Didymos, successfully altering its orbit. Hera will conduct a detailed post-impact investigation to understand exactly what happened — measuring the crater, the mass of Dimorphos, and the precise change in orbital period.
CubeSat Companions
Hera carries two CubeSats: Milani (studying Dimorphos's surface composition and dust environment) and Juventas (probing the asteroid's internal structure using low-frequency radar). Together they will provide the first complete characterisation of a binary asteroid system and validate kinetic impactor technology for deflecting threatening asteroids.