Sentinel satellites – an introduction

Discover how UK experts contribute to designing and building Sentinel satellites that enable free, open access to trustworthy, reliable and high-resolution Earth data

UK experts contribute to the Copernicus constellation of climate and weather satellites, monitoring the Earth and supplying free, instant, high resolution, open access data in real time.

What are Sentinel satellites?

There are six Sentinels, plus precursor and expansion programmes, designed to provide continuous, high-quality Earth Observation (EO). They address different aspects of land, atmosphere and oceans, between them enabling accurate monitoring of our planet. Often a Sentinel missions consists of two (or more) satellites to provide full and frequent coverage and revisits over the same location. These are labelled A, B, C, D.

Sometimes new satellites overlap in time with older ones (or with each other) to avoid gaps in data availability and to support calibration/validation phases.

A programme of investment in innovative instruments ensure that capabilities keep up with cutting-edge science, the needs of policy and decision makers. New launches in each Sentinel series enable a continuous supply of trustworthy data.

Sentinel satellites demonstrate the collaborative approach to producing cutting-edge Earth Observation instruments, for instance, around 50 companies from 13 countries across Europe were involved in developing the Sentinel-5 high-resolution imaging spectrometer system.

The first, Sentinel-1A, launched in April 2014 and, at the time of writing (September 2025), the most recent was Sentinel-5A in August 2025. It is hosted on the MetOp Second Generation (MetOp-SG) A1 satellite and promises daily global coverage of atmospheric composition (pollutants, greenhouse gases, etc.).
The next scheduled launches are:

Sentinel-1D (all weather radar) November 4^th
Sentinel-6B (sea level) November 17^th

The Sentinel satellites make Copernicus the largest space data provider in the world, and it is all openly available, as well as a catalogue of services built using Copernicus data.

The Sentinels

Sentinel-1: Polar-orbiting, all-weather, day-and-night radar imaging mission for land, ocean and emergency services.

Sentinel-2: Polar-orbiting, multispectral high-resolution imaging of major land surfaces, providing data on vegetation, soil and water cover, inland waterways and coastal areas every five days. Sentinel-2 information is also used by emergency services.

Sentinel-3: Measures sea-surface topography, sea- and land-surface temperature, ocean colour and land colour with high-end accuracy and reliability; supports ocean forecasting systems, environmental and climate monitoring.

Sentinel-4: Geostationary orbit, delivering hourly data on a wide range of trace gases and pollutants to forecast and monitor air quality over Europe.

Sentinel-5: Polar-orbiting, providing daily, global coverage for science, forecasting and public health alerts for air pollution, UV radiation, greenhouse gases and climate.

Sentinel-6: Measures global sea-surface height for operational oceanography and for climate studies.

UK expertise

The UK participates fully in Copernicus, through both its membership of the European Space Agency and EUMETSAT, and a participation agreement with the EU.

UK companies are able to compete for opportunities to contribute to development of the Sentinel satellites as the UK is a full participant in Copernicus, despite a short break in the wake of Brexit.

This also ensures that the satellites’ data remains freely available to government bodies, businesses and the science community through the Copernicus programme.

UK-based contributors include: