SAFIR

SAFIR (or Single Aperture Far-InfraRed) is a proposed NASA space observatory for far-infrared light. The plan calls for a single large mirror in diameter, cryogenically cooled to . This would feed detector arrays sensitive from 5 to 1000 µm. The possibility of servicing such a telescope in space has been evaluated. The design for SAFIR's primary mirror is large for a space-based telescope; for comparison, SAFIR's predecessor, the 2003 Spitzer Space Telescope, has a primary mirror only in diameter. SAFIR is oriented towards longer wavelengths so the mirror does not have to be as accurate compared to visible and near-infrared telescopes like the Hubble Space Telescope. Mission SAFIR will study the earliest phases of forming galaxies, stars, and planetary systems at wavelengths where these objects are brightest and which contain a wealth of unique information: from 20 micrometers to one millimeter. Most of this portion of the electromagnetic spectrum is not accessible from the ground because it is absorbed by moisture in Earth's atmosphere. The combination of large mirror size and cold temperature would be designed to make SAFIR more than 1000 times more sensitive than Spitzer or even the Herschel Space Observatory; approaching the ultimate sensitivity limits at far-infrared and submillimeter wavelengths. SAFIR's sensitivity will be limited only by the irreducible noise of photons in the astrophysical background, rather than by infrared radiation from the telescope itself.