NASA picks PRIMA telescope built with Dutch infrared tech

NASA has chosen PRIMA, a telescope designed to study the universe in far-infrared light, as its next "Probe" mission. Dutch research groups hope to build the most important parts of its main camera.

PRIMA, short for PRobe far-Infrared Mission for Astrophysics, is scheduled to launch in 2033. It will travel to a spot in space known as L2, about 1.5 million kilometres from Earth, where several other famous telescopes also operate.

Seeing through cosmic dust

Far-infrared light is invisible to our eyes, but it carries a lot of information. The very first galaxies were wrapped in thick clouds of dust, and infrared light is especially good at revealing what that dust hides. Because the universe has been expanding for billions of years, light from those early galaxies has been stretched on its way to us, arriving as far-infrared radiation.

Astronomers hope PRIMA will help answer big questions: how galaxies and the giant black holes at their centres shape each other, what interstellar dust clouds are made of, and how planets and their atmospheres form. Because this part of the spectrum has been so hard to study, scientists also expect surprises.

A telescope that has to stay cold

The challenge is heat. Almost anything warm gives off far-infrared light, including the telescope itself. A normal mirror would effectively blind its own camera.

PRIMA solves this by becoming the first space telescope with a mirror that is actively cooled, down to just 4.5 degrees above absolute zero, or roughly minus 269 degrees Celsius. With that background noise removed, PRIMA should be about a thousand times more sensitive than earlier far-infrared telescopes, and in some cases far more. Observations that once took years could take minutes.

The Dutch contribution

That extreme sensitivity depends on the camera's detectors. SRON, the Netherlands Institute for Space Research, and Delft University of Technology are the leading candidates to build the core of PRIMA's camera, called PRIMAger. This includes the detectors, their housing, and the insulation that keeps them cold.

The detectors, known as Kinetic Inductance Detectors, or KIDs, were developed in-house and are sensitive enough to pick up the faint background glow left over from the early universe.

The University of Groningen is also involved. Together with SRON, it plans to supply a special "rainbow filter" that lets different shades of far-infrared light reach different parts of the detector. This turns the camera into a colour camera without needing a bulky prism, saving both space and weight, which are always precious on a spacecraft.

Building on around fifteen years of experience from an earlier mission concept, the Dutch teams will also help design, assemble and test PRIMAger's flight hardware. If all goes to plan, a piece of Dutch engineering will soon be looking back to the dawn of the galaxies.