NASA Advances PRIMA Into Phase B as First Probe Explorers Mission

Overview

• NASA announced on Wednesday, September 23, 2026, that PRIMA has moved into Phase B, the stage for preliminary design and technology maturation of the mission.
• PRIMA is the inaugural mission in the new Probe Explorers class recommended by the National Academies' 2020 Decadal Survey to fill a mid-scale niche within the long-running Explorers Program.
• The observatory will carry a cryogenically cooled 5.9‑foot (1.8‑meter) far‑infrared telescope with three primary instruments, including an imaging polarimeter (PRIMAger) and a high‑resolution spectrometer (FIRESS), to detect cold dust and obscured phases of star and planet formation.
• Before full implementation, PRIMA faces a confirmation review that will judge technical and cost readiness; if confirmed the project cost is capped at $1.2 billion, excluding launch and other non‑project costs, and NASA is targeting a 2033 launch for a five‑year science mission.
• The Jet Propulsion Laboratory will manage PRIMA with contributions from NASA Goddard, Marshall, Caltech/IPAC as the science data center, and international partners including CNES, ASI, DLR, CSA, KASI, JAXA, and UKSA, which will broaden access to far‑infrared data and enable new studies of planet formation, galaxy growth, and cosmic dust evolution.