The Infrared Astronomical Satellite (IRAS) will be used to survey the 8 to 120 μm spectrum of the entire sky to the faintest flux levels possible by using state-of-the-art detectors and preamplifiers. As a result of a recently completed study of the telescope and focal plane, a concept has been devised that demonstrates the feasibility of using stored cryogen to cool the telescope for one year of operation in a polar twilight orbit at an altitude of 900 km. Predictions regarding noise equivalent flux density, cryogenic life-time, and the number of noise spikes caused by Van Allen belt radiation are presented. The telescope is cooled both by supercritical and by superfluid helium. The on-board signal processing includes provisions for suppressing noise spikes.
R. L. Hedden, R. L. Hedden,
"A Telescope For The Infrared Astronomical Satellite (IRAS)", Proc. SPIE 0095, Modern Utilization of Infrared Technology II, (15 November 1976); doi: 10.1117/12.955152; https://doi.org/10.1117/12.955152