The Sentinel missions provide a unique set of observations for the Copernicus programme, starting with the all-weather, day and night radar images from Sentinel-1, which are used for land and ocean services.
Sentinel-2 delivers high-resolution optical images for land services and Sentinel-3 provides data for services relevant to the ocean and land. Sentinel-4 and Sentinel-5 will provide data for atmospheric composition monitoring from geostationary and polar orbits, respectively. The Sentinel-5 Precursor also measures the atmosphere, and was launched to provide data continuity between the end of the Envisat mission in 2012 and the future launch of Sentinel-4 and 5.
The applications fall into six main categories: services for land management, services for the marine environment, services relating to the atmosphere, services to aid emergency response, services associated with security and services relating to climate change.