An instrument flown on spacecraft that uses infrared light to analyse solids and liquids. An IRS was aboard the Mariner 7 mission to the planet Mars. An IRS launched in 1998 on Deep Space 1 determined the chemical composition of the asteroid Braille. A composite infrared spectrometer (CIRS) was aboard the Cassini probe to measure the temperature, composition, and cloud structures of the planet Saturn (including its rings) and its largest satellite Titan.