The Asteroid Framing Cameras on ESA's Hera Mission

Kurzfassung

As the first asteroid deflection test, NASA's successfully hit asteroid Dimorphos (secondary of the binary asteroid 65803 Didymos) with the DART kinetic impactor on September 26, 2022. To fully characterise the physical properties of the objects, and measure precisely the effects of this impact in the context of planetary defence, ESA launched the Hera mission on 7 October 2024, with scheduled arrival at Didymos in fall 2026. Among the core payload of the mission, the Asteroid Framing Cameras are two identical imaging systems that will support navigation and scientific activities, by acquiring images from various distances and observing geometries during the course of the mission. Built by Jena-Optronik (Germany), the cameras match the requirements designed by the science team and will provide data that supports a wide range of investigations: hazard detection, system dynamics, shape reconstruction, surface morphology and mapping, and surface photometry. Each instrument is a panchromatic camera equipped with a 5.5 × 5.5 degree field of view, and an angular resolution of 93.7 micro-radians per pixel. The cameras shall provide the necessary data to address the mission requirements through a global mapping of the two components of the binary system at spatial scales of 2─3 m/pixel in the Early Characterisation Phase, 1─2 m/pixel in the Detailed Characterisation Phase, and 0.5─2 m/pixel in the Close Operation Phase. Dedicated flybys will bring the resolution down to < 10 cm/pixel on specific areas of interest on Dimorphos, such as the DART impact site and the JUVENTAS cubesat landing site. Here, we present the technical specifications of the camera, as well as the status of the calibration. We then summarise the planned operations in cruise and at the asteroids. Finally, we provide examples of the scientific investigations and products that will make use of the data returned by the cameras.