The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
Go to topicThe Infrared Atmospheric Sounding Interferometer (IASI) is a spectrometer, which is an instrument that measures the spectral distribution of incident radiation. The instrument scans through the long slit opening visible on the nadir-facing side of the spacecraft to measure infrared radiation emitted by the Earth. The control electronics and the data processing equipment are located inside the satellite. IASI's large square radiator can be seen at the side adjacent to the flight direction. The main components are a scan mirror, an internal blackbody, an optical bench containing the interferometer, a passive thermal cooler housing the cold optics and the detectors and an electronic compartment where the corner cube mechanism electronics, the scan mechanism electronics and the main acquisition electronics are installed. The IASI is slightly larger than one cubic metre and weighs about 200 kilograms.
The instrument concept is based on the Michelson interferometer. Incident radiation is divided into two beams by a beam splitter where the first beam follows a path of constant length and the other is reflected by a moving corner cube and follows a path of variable length. An optical path difference can be measured when the two beam paths are recombined. From this, data on atmospheric temperature and humidity as well as other atmospheric parameters are derived.