The Hera Space Mission in the Context of Small Near-Earth Asteroid Missions in the Past, Present and Future

Abstract

The Hera mission of the European Space Agency was launched successfully on October 7, 2024 and will perform the first rendezvous with a binary asteroid in fall 2026. It will measure in great detail the characteristics of the binary asteroid (65803) Didymos. This will include for the first time the interior of an asteroid, as well as the outcome of the impact of the NASA DART mission on the small moon, called Dimorphos; of the binary system. The first asteroid deflection test will thus be fully validated, enabling impact model extrapolations to other cases. Hera uses a unique architecture that includes for the first time a main spacecraft and two cubesats for deep space asteroid exploration. It takes place in the context of the golden age of asteroid exploration, with no less than 8 missions in development or already flying to asteroids and great successes of past missions, in particular the two recent asteroid sample return missions OSIRIS-REx by NASA and Hayabusa2 by JAXA. Up to now, all new asteroids visited by a spacecraft have generated great surprises, especially regarding their often counter-intuitive response to external actions, showing that we are still far from fully understanding the properties of these bodies in their low-gravity environment. By investigating and interacting with small asteroids, we should eventually be able to better understand and predict their properties as a function of common characteristics identified by ground-based observations. We are not there yet. In this paper, we present how Hera will contribute to this endeavor.