Astrophysicists Propose a 14-Meter Infrared Space Telescope

The Cosmos wants us to know its origins. Every moment of every day, it sends us a multitude of pointers, each one a clue to a different aspect of the universe. But the Cosmos is the original Trickster, and its horde of signals is a nearly unrecognizable cacophony of light, warped, shifted, and stretched in the course of its long journey through the expanding Universe.What are talking apes expectedto do in this situation but build another telescope skilled at understanding a specific slice of all this noisy light? That’s what astrophysicists think we should do, to nobody’s surprise.

Due to the size of the Cosmos and its continuing expansion, light from the Cosmos’s first galaxies is stretched into the infrared. This olden light holds clues to the Cosmos’s origins and, by extension, our own origins. It takes a potent infrared telescope to sense and decode this light. Earth’s atmosphere blocks infrared light so we keep building infrared space telescopes.

Infrared telescopes are also suitable for observing planets as they form. Dense environments such as protoplanetary disks are impervious to most light, but infrared light can disclose what’s going on in these planet-forming environments. The dust absorbs light, then releases it in the infrared, and scatters it too. That stuns optical telescopes, but infrared telescopes such as SALTUS are designed to deal with it.

A team of astrophysicists from Europe and the USA has joined the chorus calling for a new infrared space telescope. It’s tentatively termed SALTUS (the Single Aperture Large Telescope for Universe Studies). In a new paper, the astrophysicists outline the science case for SALTUS.“The SALTUS Probe mission will provide a powerful far-infrared (far-IR) pointed space observatory to explore our cosmic origins and the possibility of life elsewhere,” write the authors of the paper.

Title of the paper is “Single Aperture Large Telescope for Universe Studies (SALTUS): Science Overview.” Lead author is Gordon Chin from NASA’s Goddard Space Flight Center. It’s in pre-print at arxiv.org.If built, SALTUS will be unlike the powerful JWST. The JWST has four instruments that cover 600 to 28,500 nanometers or 0.6 to 28.5 microns infrared frequency range, , which is from the near-infrared to the mid-infrared. SALTUS would cover 34 to 660 μm, which falls in the far-infrared (FIR). SALTUS’ range is inaccessible to any current observatory, space or ground-based.

The baseline mission length is five years in the case of SALTUS. Infrared telescopes use sunshades and cryogenic coolers to keep temperatures down and IR light detectable. Sunshades cool the primary mirror, but the instruments need active cryogenic cooling, and those systems have a very limited lifetime that limits mission length.