SENTINEL instruments focus on different aspects of the Earth System.

ESA is developing five families of SENTINEL missions specifically for Copernicus. The SENTINELS will provide a unique set of observations for Copernicus, starting with the all-weather, day and night radar images from SENTINEL-1 to be used for land and ocean services.

SENTINEL-2 will deliver high-resolution optical images for land services and SENTINEL-3 will provide 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 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.

Monitoring the Earth's land is useful for many fields, particularly agriculture, forestry, topography, and land-cover and land-change studies.
The data can be used to track current trends and predict future changes.

Monitoring the quality and condition of our planet's atmosphere is important in that it helps us to understand how we may be affected, and is an essential tool in forecasting weather events.

Surveillance and security can be difficult to manage from the ground. Observations from space can make monitoring borders and sea routes much easier, and track developing situations.