The Sentinel satellites are the key element of the Copernicus Programme. Instead of installing as many measurement instruments as possible on a single satellite, as was the case with ENVISAT, each orbiting Sentinel satellite has its own measurement process. For reasons of high reliability and regular coverage of Earth's surface, each series will be based on a constellation of two satellites always operating in orbit. Most of the Sentinel satellites are designed and operated by ESA. The Copernicus instruments involved in atmospheric and climate measurements – specifically Sentinel-4 and 5 -- will be carried on planned meteorological EUMESAT satellites to complement other measurements on EUMETSAT polar orbiting and geostationary satellites.
The series of current Sentinel satellites and their applications
The current Copernicus Sentinel fleet (see link), is being expanded to include High Priority Candidate Missions (HPCM) to fill identified data gaps and to better accommodate additional applications. Six such HPCM missions have been defined and are under construction.
HPCM
Name and Purpose
CO2M
COPERNICUS ANTHOPOGENIC CO2 MONITORING MISSION
LSTM
LAND SURFACE TEMPERATURE MONITORING
CHIME
COPERNICUS HYPERSPECTRAL IMAGING MISSION FOR THE ENVIRONMENT