The ESA Hera Mission: Detailed Investigation of the NASA DART Impact Outcome and Characterization of the Binary Asteroid Didymos

Kurzfassung

The Hera mission is in development at the European Space Agency (ESA) in collaboration with JAXA for launch in October 2024. Consisting of a mother spacecraft and two cubesats, it will rendezvous with the binary asteroid (65803) Didymos in early 2027 and over the following 6 months will investigate the effects of the successful impact of the NASA DART probe and precisely measure the properties of Didymos and its small moon Dimorphos. DART successfully impacted on the 160 meter-size Dimorphos on 26 September 2022. Two weeks before impact, it deployed the Light Italian Cubesat for Imaging of Asteroids (LICIACube) that provided images during the few minutes following the impact. Observations from Earth and space provided distant images of the event, which were used to determine a reduction of 33 min in the orbital period of Dimorphos around Didymos. The Hera mission will investigate the outcome of the DART impact in detail. In particular, it will determine the effects of the impact on Dimorphos’ surface, e.g., whether it produced a crater, and if so its properties, and/or whether it led to global reshaping of Dimorphos. It will accurately measure the mass of Dimorphos, which will allow quantification of the momentum enhancement factor, which is a crucial parameter to evaluate the efficiency of the kinetic impactor technique. Hera will also determine in detail the physical, thermal and compositional properties of the asteroid, including the internal properties, which have a critical influence on the impact outcome. With Hera and DART together, we will have a fully documented deflection test and impact experiment that will allow us to verify our numerical impact models, to be able to extrapolate this deflection test to other asteroids and to improve our understanding of the complex geological properties and response of small asteroids.