NASA chooses PRIMA telescope to study the hidden far-infrared universe

NASA has selected a new space telescope designed to observe the universe in far-infrared light, a range of wavelengths that existing observatories cannot see effectively. The $1 billion mission, called PRIMA, will be developed and operated by NASA’s Jet Propulsion Laboratory, which is managed by Caltech.

The Probe far-Infrared Mission for Astrophysics will examine objects and processes hidden from visible-light telescopes. Caltech’s IPAC will run the mission’s science center, receiving and processing observations, preserving the resulting data and coordinating astronomers’ access to the observatory.

PRIMA is intended to address questions about how galaxies and supermassive black holes develop, how stars and planetary systems emerge, and how planetary atmospheres acquire their compositions. Scientists will also use it to investigate the origins of dust and heavier elements throughout the universe.

A colder, sharper view

The telescope and its detectors will be cooled to hundreds of degrees below zero. Lowering their temperature is intended to suppress heat-related interference that can blur or overwhelm the faint signals arriving from distant cosmic sources.

NASA says the design should make PRIMA far more sensitive than earlier far-infrared missions, while also producing unusually detailed images. The observatory will cover wavelengths from 24 to 235 micrometers. The shorter end is about one-third the thickness of a human hair; the longest wavelengths are roughly equivalent to two pieces of paper stacked together.

A 1.8-metre cryogenically cooled telescope will feed two principal instruments. PRIMAger will use imaging polarimetry to survey broad areas of the sky, while FIRESS will provide high-resolution, multimode spectroscopy. Together, the instruments will allow researchers to study both the locations of distant objects and the physical and chemical information encoded in their light.

The mission’s targets include the birth of stars and planetary systems, the changing properties of galaxies over cosmic history, exoplanet atmospheres and bodies within our own solar system. NASA associate administrator Nicky Fox described PRIMA as a new way to investigate the formation of planets, stars and black holes, as well as the history of water on Earth.

A new mission category

PRIMA will be NASA’s first astrophysics mission in the probe class. The category was recommended by the Astro 2020 Decadal Survey, led by Caltech physicist Fiona Harrison. Probe missions are intended to occupy the space between smaller Explorer missions, such as SPHEREx, and major flagship observatories including the Nancy Grace Roman Space Telescope.

JPL will oversee the mission’s architecture and systems engineering, and will integrate the spacecraft with its scientific payload. Caltech and JPL have been involved in PRIMA’s concept and technology development, drawing on decades of work in infrared astronomy.

The observatory will rely on superconducting microwave kinetic inductance detectors, also known as MKIDs or KIDs. Caltech physicist Jonas Zmuidzinas and JPL engineer Rick LeDuc developed the technology in 1999. Early work on using superconducting materials to detect far-infrared radiation began informally at a coffee shop near Caltech, according to the university.

The detectors were tested at the now-closed Caltech Submillimeter Observatory in Hawaii in 2007 and later flew on ground-based and balloon instruments. During the past five years, researchers at Caltech, JPL and JPL’s Microdevices Laboratory have worked to improve the arrays’ sensitivity and make them robust enough for spaceflight. Prototype arrays have now demonstrated the readiness required for PRIMA.

Zmuidzinas said the technology’s long development has created an opportunity for a major increase in sensitivity in a relatively underexplored part of the spectrum. Caltech said the anticipated improvement could be about a thousandfold.

Data for the wider astronomy community

IPAC will support mission planning, observation scheduling, calibration and data processing. The telescope’s observations will be stored in the Infrared Science Archive, which already holds data from more than 20 NASA missions.

The center will draw on experience from missions including NASA’s Spitzer Space Telescope, which operated from 2003 to 2020, NASA’s SPHEREx and the European Space Agency’s Herschel observatory. IPAC has also supported observatories on Earth, building expertise that will be applied to PRIMA’s operations.

Once the observatory is working at full capacity, approximately 75 percent of its observing time is expected to be allocated through peer-reviewed proposals from the broader scientific community. Nearly 200 proposed uses for PRIMA data have already been submitted by more than 400 astronomers.

One area of interest is the study of molecular outflows from galaxies. These streams of material can accompany periods of rapid star formation or activity from a galaxy’s central black hole, and may influence how galaxies grow. Herschel observed such outflows in a limited number of nearby galaxies; PRIMA is intended to extend that kind of research across a much wider range of cosmic history.