Prima: NASA will try to build a billion-dollar space telescope in record time

NASA is moving ahead with PRIMA, a Probe-class far-infrared observatory capped at $1.2 billion (excluding launch) and targeted for launch in 2033. PRIMA will carry a 1.8‑meter primary mirror into a Sun-Earth L2 orbit to observe 24-235 µm wavelengths, with primary optics cooled to about 4.5 K and kinetic inductance detector arrays chilled to ~100 mK. To accelerate development and reduce cost, PRIMA will reuse and modify a spare cryocooler from the James Webb Space Telescope (swapping in helium‑3), aiming to reach flight readiness in roughly seven years and keep the finished observatory under 3.4 metric tons. Science goals include probing planet and atmosphere formation, the coevolution of galaxies and black holes, and the evolution of dust, metals, and water across cosmic time - extending and deepening far‑infrared capabilities beyond Spitzer, Webb, and Europe’s Herschel.

PRIMA is the inaugural mission in a new Probe Explorer tier designed to bridge lower‑cost Explorer missions and multibillion‑dollar flagships, with NASA authorizing Phase B work toward a preliminary design review. A competing Probe concept (an X‑ray mission) was disqualified for schedule and budget risks, highlighting programmatic pressures and management challenges at centers involved in prior studies. Lessons from the Roman telescope’s on‑budget, on‑time development will inform both PRIMA and long‑range flagship planning for the Habitable Worlds Observatory, which is being studied for the 2040s with an early cost estimate near $11 billion and broad international participation expected.