NASA Picks PRIMA, Its First-Ever Probe Explorers Telescope

NASA selected the PRIMA far-infrared telescope as the first mission in its new Probe Explorers class, targeting a 2033 launch for a five-year survey.

NASA announced Wednesday that PRIMA (PRobe far-Infrared Mission for Astrophysics) is moving into Phase B, the stage of preliminary design and technology development. The far-infrared space telescope is the first mission in a new astrophysics class called Probe Explorers, created within NASA's decades-old Explorers Program, which dates back to Explorer 1 in 1958 and has launched more than 100 missions. If it passes a confirmation review, PRIMA is capped at $1.2 billion in project costs, excluding launch, and is targeted for a 2033 launch on a planned five-year mission. NASA's Jet Propulsion Laboratory will manage the project, with Goddard and Marshall among the partners.

PRIMA will carry a 1.8-meter, actively cooled aluminum telescope and survey the universe in far-infrared wavelengths, a band JWST was not built to reach. According to Live Science, Johns Hopkins astronomer Meredith MacGregor explained that key spectral lines needed to quantify water's role in planet formation and measure gas masses in planet-forming disks are found only at these longer wavelengths, so JWST cannot address them. The Max-Planck-Gesellschaft reports PRIMA will bridge the observational gap between existing infrared observatories such as JWST and radio telescopes, covering wavelengths from 24 to 235 micrometers, a range Caltech describes.

The mission targets three big questions: where exoplanets come from, how galaxies and their central black holes grew over cosmic history, and how dust and heavy elements built up over time. According to Live Science, co-investigator Lee Armus of Caltech is particularly excited about how PRIMA will reveal the role of powerful molecular outflows in shaping star formation and supermassive black hole growth. The Max-Planck-Gesellschaft notes the mission could also illuminate how water, including Earth's water, came to be, and NASA associate administrator Nicky Fox called PRIMA 'humanity's next window into the deep universe.'

The Max-Planck-Gesellschaft reports that Germany's Max Planck Institute for Astronomy proposes to contribute high-precision, actively controlled beam-steering mirrors — two-axis focal plane choppers, one each for the PRIMAger imager and the FIRESS spectrometer — to stabilize the field of view. Caltech, per Spaceflight Now reporting cited by NewsCord, describes PRIMAger as an imaging polarimeter for mapping large sky areas and FIRESS as a high-resolution multimode spectrometer. International partners named by NASA include CNES, ASI, DLR, CSA, KASI, JAXA and the UK Space Agency, and IPAC will serve as the mission science center.

PRIMA exists because the National Academies' 2020 Decadal Survey recommended NASA create the Probe Explorers class, sized between flagship missions like the $10 billion JWST and smaller Explorer efforts. NASA funded two concepts at $5 million apiece in 2024 — PRIMA and the Advanced X-ray Imaging Satellite — before selecting PRIMA this week, according to Live Science. The agency said the choice rested on scientific merit aligned with the Decadal Survey, feasibility on cost and schedule, and technologies that could support future large missions. The Explorers Program's track record includes Uhuru and COBE, missions whose investigators earned Nobel Prizes.

PRIMA is not guaranteed to fly yet: the mission faces a confirmation review based on technical, programmatic and cost performance before it can enter Phase C implementation, per NASA statements carried by Astrobiology Web. If confirmed, launch is targeted for no earlier than 2033. NASA astrophysics director Shawn Domagal-Goldman said Webb and Roman established a cadence of premier missions in both halves of the decade, and that PRIMA will kick off the next decade as part of a pipeline of such missions — extending the telescope fleet's survey power into far-infrared light for a more comprehensive view of the cosmos.