It potentially offers about 7000 hours of science time per year. It is a multiuser observatory accessible to astronomers from all over the world. But that was only the beginning. In November 1995 ESA launched its Infrared Space Observatory, ISO, which has allowed a much closer look, a more detailed perception of the 'infrared scenery'. ISO data are still being analyzed by the scientists, but the spectacular results obtained so far are those of a highly successfull mission.
Infrared radiation is invisible for the human eye.
It's actually 'heat', or thermal radiation. Even objects that we think of as being very cold, such as an ice cube, emit infrared radiation. For this reason infrared telescopes can observe astronomical objects that remain hidden for optical telescopes, such as cool objects that are unable to emit in visible light. But the Earth's atmosphere acts as an 'umbrella' for most infrared wavelengths, preventing them from reaching the ground. That's the reason why a space telescope is needed to detect this kind of radiation invisible to the human eye and to optical telescopes.