The ESA Hera mission to the near-Earth asteroid binary Didymos: planetary defense and science return

The Hera mission is under development in the ESA Space Safety Program for launch in 2024. Hera will contribute to the first deflection test of an asteroid, in the framework of the international NASA- and ESA-supported Asteroid Impact and Deflection Assessment (AIDA) collaboration. ESA's Hera spacecraft will rendezvous the binary asteroid 65803 Didymos four years after the impact of NASA’s DART on its small moon, called Dimorphos. It will perform the measurements necessary to understand the effect of the DART impact on Dimorphos, in particular its mass, its internal structure, the direct determination of the momentum transfer and the detailed characterization of the crater left by DART. Hera will also provide unique information on many current issues in asteroid science. It will rendezvous for the first time with a binary asteroid. Its secondary, Dimorphos, has a diameter of only 160 m in diameter. So far, no mission has visited such a small asteroid. Moreover, for the first time, internal and subsurface properties will be directly measured. From small asteroid internal and surface structures, through rubble-pile evolution, impact cratering physics, to the long-term effects of space weathering in the inner Solar System, Hera will have a major impact on many fields. Hera is thus an amazing European contribution to the international planetary defense and asteroid exploration era