IRAS

Launched in 1983, IRAS is famous for conducting the first comprehensive all-sky survey at infrared wavelengths, leading to the discovery of infrared "cirrus" in the Milky Way. It also discovered the first dust disk around a star, Vega, hinting at potential planetary systems. Additionally, it identified several comets and asteroids, including the unusual object 3200 Phaethon.

The IRAS mission was a joint international project involving NASA in the United States, the Netherlands Agency for Aerospace Programmes (NIVR), and the United Kingdom's Science and Engineering Research Council (SERC). The satellite was launched on a Delta rocket from Vandenberg Air Force Base. The mission operations and data processing were shared among the three partner nations.

The IRAS satellite was launched in January 1983 and operated for 10 months until its liquid helium coolant was depleted in November 1983. The liquid helium was necessary to keep the infrared detectors cold enough to function and avoid thermal noise from the satellite itself. Although the official operational phase ended in 1983, the data it collected continued to be analyzed for years, with the catalog officially finalized in 1989.

Infrared detectors are highly sensitive to heat, meaning that the satellite's own operating temperature would completely obscure the faint infrared light from distant stars and galaxies. To prevent this, the telescope was bathed in liquid helium to cool it down to just a few degrees above absolute zero. Once the coolant evaporated, the instrument became too warm to detect cosmic infrared radiation.