Meteorology was the first scientific discipline to use space capabilities in the 1960s, and today satellites provide observations of the state of the atmosphere and ocean surface for the preparation of weather analyses, forecasts, advisories and warnings, for climate monitoring and environmental activities. Three quarters of the data used in numerical weather prediction models depend on satellite measurements (e.g. in France, satellites provide 93% of data used in Météo-France’s Arpège model). Three main types of satellites provide data: two families of weather satellites and selected environmental satellites.