Design and development of the PRIMAger instrument for PRIMA

PRIMA (PRobe far-Infrared Mission for Astrophysics) is an infrared observatory featuring a 1.8 m telescope cooled to 4.5 K, designed to operate for the next decade. Currently in the concept study phase, it includes two instruments, one of which is PRIMAger developed by an European consortium. PRIMAger offers two modes: hyperspectral (24–84 µm, spectral resolution ≥ 8) and polarimetric (4 broad bands from 80 to 264 µm, measuring three polarization orientations). It uses ultra-sensitive KID detectors cooled at 0.12K and an opto-mechanical structure at 1 K. A major challenge is in-flight verification. The paper outlines the technical requirements, design, and development strategy, including a rigorous test plan.