History of the telescope of the IRAS satellite in 1983 revolutionized infrared astronomy from space. This reflecting telescope which had a mirror, operated for nine months until its supply of coolant (liquid helium) ran out. It surveyed the entire sky detecting 245,000 infrared sources—more than 100 times the number previously known. Although optical telescopes can image the near ultraviolet, the ozone layer in the stratosphere absorbs ultraviolet radiation shorter than 300 nm so most ultra-violet astronomy is conducted with satellites. Ultraviolet telescopes resemble optical telescopes, but conventional aluminium-coated mirrors cannot be used and alternative coatings such as magnesium fluoride or lithium fluoride are used
Greenhouse gas monitoring glowing nichrome filament radiates broadband IR radiation which splits into two beams and passes through the gas cells. Carbon dioxide absorbs some of the radiation, allowing more radiation that passes through the reference cell to reach the detector than radiation passing through the sample cell. Data is collected on a strip chart recorder. The concentration of carbon dioxide in the sample is quantified by calibrating with a standard gas of known carbon dioxide content. Titrimetry is another method of measuring atmospheric carbon dioxide that was first used by a Scandinavian group at 15 different ground stations. They began passing a