ESA Science & Technology - Fact Sheet

ESA's Infrared Space Observatory (ISO) is an astronomical satellite that was operational between November 1995 and May 1998. It operated at wavelengths from 2.5 to 240 microns, in the infrared range of the electromagnetic spectrum. Because the atmosphere acts as an 'umbrella' for most infrared wavelengths -preventing them from reaching the ground- a space telescope is needed to detect this kind of radiation invisible to the human eye and to optical telescopes.