Development of processes and tests for the creation of the primary mirror and the flexure hinges for the Ariel space telescope

The ESA’s Ariel space mission, scheduled for launch in 2029, aims to study the atmospheres of ~ 1000 exoplanets in the wavelengths between Visible and Infrared. Ariel’s telescope, to the Cassegrain off-axis type, will employ an elliptical primary mirror with a parabolic surface measuring 1.2x0.7m, entirely made of Aluminum T6061 alloy. Notably, this marks the first instance of manufacturing a primary mirror of such dimensions in aluminum for Infrared applications, and this required a comprehensive study of production processes. Additionally, aluminum flexure hinges have been designed and tested to ensure an optimal connection between the primary mirror and the optical bench, minimize optical surface deformation due to its low density, maximize heat exchange, and maintain a high degree of structural robustness. This work describes all the development processes and tests to realize the primary mirror and flexure hinges. These activities will provide a solid foundation for future space missions.