Tolerance-driven design of flight shell mandrels and engineering model alignment for the EUV Telescope of the MANTIS mission

MANTIS (Monitoring Activity of Nearby sTars with UV Imaging and Spectroscopy) is a 16U CubeSat mission proposed by the University of Colorado at Boulder and funded by NASA, scheduled for launch in 2027. MANTIS is designed to characterise the high-energy stellar radiation that drives atmospheric photochemistry and escape on extrasolar planets, to understand the environment for habitable-zone exoplanets. It will conduct simultaneous observations of exoplanet host stars from Extreme-UltraViolet to visible wavelengths. MANTIS will offer the first EUV astrophysics capability in over 20 years, with spectral surveys carried out in conjunction with the James Webb Space Telescope. INAF is contributing to the mission on a technological level by developing the innovative extreme-ultraviolet grazing incidence Hettrick-Bowyer telescope. The telescope is composed of an optical system consisting of a parabolic primary mirror with an external diameter of 10.5 cm, a pinhole located at the focus of the primary, and an elliptical refocusing secondary mirror. This thesis work has been carried out at the INAF-OABrera and overlaps with the initial phase of the project. The thesis focuses on the tolerances analysis for the optical components, both in terms of shape error and alignment requirements. The results of the numerical simulations enable the evaluation of the impact of the mirrors' surface errors on the optical quality of the telescope, serving as the basis for the mandrel design used in manufacturing nickel shells for the flight model. The next part outlines the manufacturing of the electroformed nickel shells, discussing the design, features, geometry and fabrication of the mandrels to be used in the replica process. The final part presents the alignment procedure and the design of the optics handling system to be used on the UV optical bench for the engineering model assembly, which is made of diamond-turned aluminium mirror shells.

Telescopio EUV, missione MANTIS, Hettrick-Bowyer design, polinomi di Zernike, allineamento ottico