Sentinel-2 Ground Segment

The ground segment is composed of the Core Ground Segment, the Collaborative Ground Segment and the Copernicus contributing missions’ ground segments.

The core ground segment monitors and controls the SENTINEL spacecraft, ensures the measurement data acquisition, processing, archiving and dissemination to the final users. In addition, it is responsible for performing conflict-free mission planning according to a pre-defined operational scenario, and ensures the quality of data products and performance of the space-borne sensors by continuous monitoring, calibration and validation activities, guaranteeing the overall performance of the mission.

Copernicus Ground Segment Architecture

The Copernicus ground segment is complemented by the SENTINEL collaborative ground segment, which was introduced with the aim of exploiting the SENTINEL missions further. This entails additional elements for specialised solutions in different technological areas such as data acquisition, complementary production and dissemination, innovative tools and applications, and complementary support to calibration and validation activities.

The Copernicus contributing mission ground segments, with their own specific control functions, data reception, data processing, data dissemination and data archiving facilities, deliver essential data complementing the SENTINEL missions.


Core Ground Segment

The SENTINEL core ground segment allows all SENTINEL data to be systematically acquired, processed and distributed. It includes elements for monitoring and controlling the SENTINEL satellites and for downloading, processing and disseminating the data to users. It also has mechanisms for monitoring and controlling the quality of data products, as well as for data archiving. Infrastructure is ‘distributed’, meaning that various centres are in different locations but linked together and coordinated. Despite the complexity of the system, users are offered a single virtual access point for locating and downloading products.

The main facilities of the SENTINEL core ground segment are:

  • The Flight Operations Segment (FOS) – responsible for all flight operations of the SENTINEL satellites, including monitoring and control, execution of all platform activities and commanding of the payload schedules.
  • The Core Ground Stations (CGS) – where the SENTINEL data are downlinked and products are generated in near real-time. A network of X-band ground stations allows the downlink of all SENTINEL data. These are complemented by utilisation of the European Data Relay Satellite (EDRS) for additional downlink of SENTINEL data to EDRS ground stations.
  • The Processing and Archiving Centre’s (PACs) – where systematic non-time critical data processing is performed. All data products are archived for online access by users. A network of PACs supports all processing and archiving of SENTINEL data.
  • The Mission Performance Centres (MPCs) – responsible for calibration, validation, quality control and end-to-end system performance assessment. The MPCs include expert teams for specific calibration/validation, off-line quality control, algorithm correction and evolution activities.
  • The SENTINEL Precise Orbit Determination (POD) facility – makes use of the GNSS receiver data on the SENTINELS to deliver the orbital information needed to generate data products.
  • The Copernicus Space Component Wide Area Network (CSC WAN) – allows all products and auxiliary data to be carried across the various ground segment facilities and provides disseminated data products to end users.

All SENTINEL data are systematically processed up to the designated level and according to different timelines, ranging from near real-time to non-time critical, available typically within 3-24 hours of being sensed by the satellite.


Payload Data Ground Segment (PDGS)

The Payload Data Ground Segment (PDGS) is responsible for exploitation of the instrument data. The PDGS is operated from ESA’s Centre for Earth Observation also known as the European Space Research Institute (ESRIN) in Frascati, Italy. The PDGS operationally generates the user products and distributes processed Level-1C and Level-2A products.

The PDGS includes the facilities responsible for mission control (mission planning, production planning), quality control (calibration, validation, quality monitoring, instrument performance assessment), precise orbit determination, user services interface and acquisition, processing and archiving.

Real-time sensed data as well as data played back from on-board saved data are downlinked directly to ground or via the European Data Relay Satellite (EDRS), received, down-converted, demodulated and transferred to the processing facilities for systematic generation and archiving of Level-0 and Level-1/2 data products.

The PDGS is expected to receive and process 2.4 TBytes of compressed raw data per day for the two satellites in addition to data from all other ESA missions. MSI Level-0 data are processed to produce Level-1 and Level-2 products applying all the necessary processing algorithms and formatting techniques.

The PDGS is distributed over several core centres including Core Ground Stations (CGS), Processing and Archiving Centres (PAC), Mission Performance Centres (MPC) and Precise Orbit Determination (POD) facilities.

Core Ground Stations – the network of X-band core ground stations located in Alaska, USA, Matera, Italy, Maspalomas, Spain and Svalbard, Norway, are responsible for data acquisition and near real-time processing.

Processing and Archiving Centres – PACs perform long-term data archiving, data access and systematic non-time critical data processing. Archiving and long-term preservation of data is ensured for all Level-0 data and for a set of configurable systematic higher level products.

Mission Performance Centres – MPCs are responsible for calibration, validation, quality control and end-to-end system performance assessment. The MPCs include expert teams for specific cal/val, off-line quality control and algorithm correction activities.

Precise Orbit Determination – POD facilities make use of the GNSS receiver data on-board the SENTINEL satellites to deliver the orbital information needed for generation of mission products.

SENTINEL-2 Receiving Stations and Off-line Processing and Archiving Centres

Coordination between the centres is provided through the Payload Data Management Centre (PDMC) at ESRIN in Frascati, Italy.

SENTINEL-2 products are provided to the user through online access. Near real-time dissemination is allocated to the receiving stations and less time-critical data dissemination is allocated to the assembly, processing and archiving centres.


CPOD Service

The Copernicus POD (Precise Orbit Determination) Service is part of the Copernicus PDGS Ground Segment of the Sentinel missions and is in charge of the provision of Precise Orbital Products and auxiliary data files to the PDGS. The Copernicus POD Service was developed and is being operated by a GMV-led consortium from Tres Cantos, Spain. Additionally, for Sentinel-3 there is a POD Instrument Processing Facility in charge of generating the Near Real Time products running directly at the S-3 PDGS facilities.

This web page contains basic information describing the CPOD Service. Moreover, the CPOD Service regularly provides dynamic content for users who want to use the POD Orbital Products. This information can be found under the Technical Guides section.

The Copernicus POD Service interacts with many different entities, internal and external to the Copernicus program. The following is a description of the main elements involved in the Copernicus POD Service:

GMV: leader of the consortium in charge of running the Copernicus POD Service. GMV is responsible for the proper function of the CPOD Service, including the generation and delivery of all precise orbital products and auxiliary date meeting accuracy and timeliness requirements, together with the coordination activities between the different elements that interact with the CPOD Service.

Payload Data Ground Segment (PDGS): The PDGS is the main provider of inputs to the CPOD Service (GNSS measurements, attitude information, etc) and the unique recipient of the products generated.

Sentinels Flight Operations Segment (FOS): Located at ESOC for Sentinel-1, Sentinel-2 and Sentinel-3 (for Sentinel-3 only during the commissioning phase) and EUMETSAT for Sentinel-3 during the routine operation phase, it is the provider of operational orbits, manoeuvre information and the satellite mass and centre of gravity evolution.

External GNSS data Provider (EGP): A dedicated high accuracy and reliability external GPS data provider (VERIPOS). High rate orbits and clocks are provided with different levels of timeliness and accuracy. In case of unavailability a back-up solution has been put in place based on magicGNSS, a GMV solution for GNSS accurate products. IGS final orbits and clocks are also retrieved and used in the computation of the NTC products.

International Laser Ranging Service (ILRS): They provide Sentinel-3 SLR data to be used in the POD processing, while the Copernicus POD provides orbit predictions (CPF files) of Sentinel-3 to ILRS.

External Auxiliary providers: Earth Orientation Parameters and leap seconds from IERS (International Earth Rotation Service), solar and magnetic activity information for geodesy computations from NOAA and atmospheric gravity models from NASA.

Centre National d’Études Spatiales (CNES): They provide Sentinel-3 orbital and attitude products (for comparison purposes), together with DORIS data. Copernicus POD provides GNSS Observation RINEX files to CNES.

External Validation: A number of independent institutions (ESOC, DLR, TUM, AIUB and TU Delft) provide independent orbit solutions for validation purposes to assess the quality of the CPOD products. For Sentinel-3 other centres will provide orbital products, including CNES and EUMETSAT.

CPOD Quality Working Group (CPOD QWG): The main purpose is to monitor the performance of the operational POD products (both the orbit products as well as the input tracking data) and to define potential and future enhancements to the orbit solutions.

Copernicus POD Service Elements and Interfaces



The Copernicus POD Quality Working Group (CPOD QWG) is a dedicated group of experts in Precise Orbit Determination who provide independent POD solutions, allowing to carry out external validation of the operational POD products. Additionally, they perform analysis to monitor the quality of the input tracking data, conduct research on improved models and algorithms and define potential and future enhancements to the orbit solutions. The members of the CPOD QWG meet usually twice a year to present the main findings since the previous meeting and to decide on which aspects are worth investigating in the near future.

The main tasks of the CPOD QWG can be summarised as follows:

  • Gather information: Through attending conferences and interactions with the IDS Analysis Working Group, the Copernicus POD QWG gathers information on any potential algorithm evolution that could benefit the Copernicus POD system. Besides, the interaction with the international services of all observation techniques available for the Sentinels (IGS, IDS and ILRS) is maintained. The IERS conventions and realisations of the ITRF are updated. The evolution of the (CNES) GDR standards is also considered.
  • Evaluate: Evolutions are evaluated on a separate validation with at least other POD centre (CNES; ESOC). Quality indicators evaluated are orbit overlap, tracking data residuals, the magnitude of the empirical accelerations, external orbit comparison, and in the case of Sentinel-3, altimeter crossover performance.
  • Make recommendations: The most promising enhancements are presented and discussed during the QWG meetings.
  • Implement changes: After the internal and external evaluation and approval of ESA the algorithm evolution is included in the next upgrade of the POD.
  • Membership: The composition of the Copernicus POD QWG is composed by representatives of ESA, EUMETSAT, CNES, NASA, GMV, POSITIM, DLR, TUM, AIUB, TU Delft, DGFI, GFZ, CLS, Sentinel-3 Validation Team Meeting, the Mission Performance Centre of each Sentinel, Payload Data Ground Segment of each mission, the Copernicus Service and the Post-Launch Support Office.

The main analysis presented and conclusions reached in each CPOD QWG meeting, held twice a year, are included in the S2 POD Document Library.


Flight Operations Segment (FOS)

The Flight Operation Segment (FOS) is responsible for command and control of the satellite and is operated from ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany.

ESA’s European Space Operations Centre

The FOS consists of the Ground Station and Communications Network, Flight Operations Control Centre and a General Purpose Communication Network.

The FOS provides the capability to monitor and control the satellite during all mission phases including the Flight Dynamics System facility responsible for orbit determination and prediction, and for the generation of attitude and orbit control telecommands.

The main functions of the FOS include:

Mission planning

Long term planning of spacecraft and payload activities, covering the complete orbit cycle and repeating indefinitely. Short term planning, nominally every 2 weeks, in the form of updated mission schedules.

Spacecraft status monitoring 

Processing housekeeping telemetry, providing information about the status of all spacecraft subsystems and attitude.

Spacecraft control 

Taking control actions by means of telecommands, based on the spacecraft monitoring and following the mission plan.

Orbit determination and control

Using tracking data and implementing orbit manoeuvres, ensuring required orbital conditions are achieved.

Attitude determination and control

Using processed attitude sensor data from spacecraft monitoring and by commanded updates of control parameters through the on-board attitude control system.

On-board software maintenance

Integrating software images received from the spacecraft manufacturer (pre-launch and post-launch) into the telecommand process.


Communicating (TM/TC) with one satellite at a time.


Sentinel-2 Satellite Description

Each SENTINEL-2 satellite weighs approximately 1.2 tonnes. SENTINEL-2A and SENTINEL-2B have both been launched with the European launcher VEGA.
The satellite lifespan is 7.25 years, which includes a 3 month in-orbit commissioning phase. Batteries and propellants have been provided to accommodate 12 years of operations, including end of life de-orbiting manoeuvres.

Two identical SENTINEL-2 satellites operate simultaneously, phased at 180° to each other, in a sun-synchronous orbit at a mean altitude of 786 km. The position of each SENTINEL-2 satellite in its orbit is measured by a dual-frequency Global Navigation Satellite System (GNSS) receiver. Orbital accuracy is maintained by a dedicated propulsion system.

The SENTINEL-2 satellite system was developed by an industrial consortium led by Astrium GmbH (Germany). Astrium SAS (France) is responsible for the MultiSpectral Instrument (MSI).

The MSI works passively, by collecting sunlight reflected from the Earth. New data is acquired at the instrument as the satellite moves along its orbital path. The incoming light beam is split at a filter and focused onto two separate focal plane assemblies within the instrument; one for Visible and Near-Infra-Red (VNIR) bands and one for Short Wave Infra-Red (SWIR) bands . The spectral separation of each band into individual wavelengths is accomplished by stripe filters mounted on top of the detectors.

The optical design of the MSI telescope allows for a 290 km Field Of View (FOV).

A shutter mechanism prevents the instrument from direct illumination by the sun in orbit and to avoid contamination during launch. The same mechanism functions as a calibration device by collecting the sunlight after reflection by a diffuser.


MultiSpectral Instrument (MSI)

The MultiSpectral Instrument (MSI) uses a push-broom concept. A push-broom sensor works by collecting rows of image data across the orbital swath and utilises the forward motion of the spacecraft along the path of the orbit to provide new rows for acquisition. The average period of observation over land and coastal areas is approximately 17 minutes and the maximum period of observation is 32 minutes.

Light reflected up to the MSI instrument from the Earth and its atmosphere is collected by a three-mirror (M1, M2 and M3) telescope and focused, via a beam-splitter, onto two Focal Plane Assemblies (FPAs): one for the ten VNIR wavelengths and one for the three SWIR wavelengths.

SENTINEL-2 Satellite. (Astrium GmbH, Germany)

Radiometric calibration of the MSI instrument is achieved via a diffuser fitted on the inside face of the combined Calibration and Shutter Mechanism (CSM).

MSI Calibration and Shutter Mechanism showing the Sun calibration diffuser. (Sener, Spain and CSL, Belgium)

To achieve the required 290 km swath width, both the VNIR and SWIR FPAs are composed of 12 detectors, staggered in two horizontal rows. Further separation of the individual VNIR and SWIR bands is achieved using stripe filters overlaying the detectors. The VNIR Focal Plane is shown.

VNIR Flight Focal Plane (Astrium SAS (France) and e2v Technologies (UK))


Resolution and Swath

Spatial and Spectral Resolutions

The surface area measured on the ground and represented by an individual pixel, is termed as the spatial resolution. For Sentinel-2, there are three possible spatial resolutions (see table).

Spectral resolution is defined as a measure of ability to resolve features in the electromagnetic spectrum. Sentinel-2 spectral resolutions (Bandwidth) are provided in the table.

NOTE: The Bandwidth (nm) is measured at Full Width Half Maximum (FWHM).

Spatial Resolution
Band NumberS2A
Central Wavelength
Central Wavelength
Wavelengths and Bandwidths of the three Spatial Resolutions of the MSI instruments

Radiometric Resolution

Radiometric resolution is a measure of the ability of an imaging system to record different levels of brightness or tone. The radiometric resolution of Sentinel-2 is 12-bit. This gives a potential range of brightness levels from 0 – 4 095.

Note: More information on Spatial and Radiometric Resolutions used in Sentinel-2 Mission

Temporal Resolution

Temporal resolution is the amount of time, expressed in days, that elapses before a satellite revisits a particular point on the Earth’s surface. The satellites in the Sentinel-2 constellation will provide a revisit time of five days at the equator in cloud-free conditions.

Swath Width

The swath width of Sentinel-2 is 290 km. In comparison, the swath width of Landsat 5 TM and Landsat 7 ETM+ is 185 km, and the swath width of SPOT-5 is 120 km.



The Sentinel-2 mission orbit is sun-synchronous. Sun-synchronous orbits are used to ensure the angle of sunlight upon the Earth’s surface is consistently maintained. Apart from small seasonal variations, anchoring of the satellites orbit to the angle of the sun minimises the potential impact of shadows and levels of illumination on the ground. This ensures consistency over time and is critical in assessing time-series data.

Sentinel-2A and Sentinel-2B occupy the same orbit, but separated by 180 degrees.The mean orbital altitude is 786 km. The orbit inclination is 98.62° and the Mean Local Solar Time (MLST) at the descending node is 10:30 (am). This value of MLST was chosen as a compromise between a suitable level of solar illumination and the minimisation of potential cloud cover. The MLST value is close to the local overpass time of Landsat and almost identical to that of SPOT-5, permitting the integration of Sentinel-2 data with existing and historical missions, and contributing to long-term time series data collection.

The following table contains a summary of useful orbital information for Sentinel-2A and –2B:

AltitudeInclinationPeriodCycleGround-track deviationLocal Time at Descending Node
786 km98.62 deg100.6 min10 days+- 2 km10:30 hours

The KML data file informing on the position of the Sentinel-2A and Sentinel-2B Relative Orbits for a full Cycle (143 Orbits) with a time step of 10 seconds is available:


Sentinel-2 Mission Objectives

The objectives for SENTINEL-2 are set out in the Mission Requirements Document. SENTINEL-2 mission objectives are to provide:

  • systematic global acquisitions of high-resolution, multispectral images allied to a high revisit frequency
  • continuity of multi-spectral imagery provided by the SPOT series of satellites and the USGS LANDSAT Thematic Mapper instrument
  • observation data for the next generation of operational products, such as land-cover maps, land-change detection maps and geophysical variables.

These high-level objectives, determined after consultation with users, will ensure that SENTINEL-2 makes a significant contribution to Copernicus themes such as climate changeland monitoringemergency management, and security.

With its 13 spectral bands, 290 km swath width and high revisit frequency, SENTINEL-2’s MSI instrument supports a wide range of land studies and programmes, and reduces the time required to build a European cloud-free image archive. The spectral bands of SENTINEL-2 will provide data for land cover/change classification, atmospheric correction and cloud/snow separation.


Sentinel-2 Overview

SENTINEL-2 is a European wide-swath, high-resolution, multi-spectral imaging mission. The full mission specification of the twin satellites flying in the same orbit but phased at 180°, is designed to give a high revisit frequency of 5 days at the Equator.

SENTINEL-2 carries an optical instrument payload that samples 13 spectral bands: four bands at 10 m, six bands at 20 m and three bands at 60 m spatial resolution. The orbital swath width is 290 km.

The twin satellites of SENTINEL-2 provides continuity of SPOT and LANDSAT-type image data, contribute to ongoing multispectral observations and benefit Copernicus services and applications such as land management, agriculture and forestry, disaster control, humanitarian relief operations, risk mapping and security concerns.

Instrument Payload

Each of the satellites in the SENTINEL-2 mission carries a single payload: the Multi-Spectral Instrument (MSI).

Related Content:

The SENTINEL-2 System



The spectral band configuration of the SENTINEL-2 mission arose as a result of consultation with the user community during the design phase. The existing Copernicus/GMES Service Elements (GSEs) services were developed around the use of LANDSAT and SPOT wavelengths, and the service requirements for SENTINEL-2 have these at their core.

Comparison of Spatial Resolution and Wavelength Characteristics of SENTINEL-2 Multispectral Instrument (MSI), the Operational Land Imager (OLI) On-Board LANDSAT-8, and SPOT 6/7 Instruments (from ESA Special Publication 1322/2)

Narrowing the width of the SENTINEL-2 spectral bands limits the influence of atmospheric constituents, including water vapour. The original LANDSAT Near Infra-Red (NIR) band (760-900 nm) was found to be heavily contaminated by water vapour and not sensitive enough to parameters such as soil iron oxide content. The narrowness of the 8a band at 865 nm in the NIR is designed to avoid contamination from water vapour yet still be able to represent the NIR plateau for vegetation and be sensitive to iron oxide content for soil.

Precise aerosol correction of acquired data is enabled by the inclusion of a spectral band in the blue domain at 443 nm (Band 1) in the SENTINEL-2 configuration. The 443 nm band was used in previous missions: for the calculation of the ENVISAT MERIS Global Vegetation Index (MGVI), and in atmospheric corrections for NASA’s MODIS sensor.

Due to its potential impact on reflectance values, its use as an indicator in weather forecasting and its role in the trapping of incoming solar radiation, the presence of cirrus cloud needs to be addressed. Adding a spectral band at 1 375 nm (band 10) enables cirrus detection. The correction of data for thin cirrus can be managed using Visible to Near Infra-Red (VNIR) band information. This band is included in the MODIS instruments as band 26, and its is used in current US multispectral missions such as LANDSAT-8 and the Visible Infrared Imaging Radiometer Suite (VIIRS).


Thematic Areas and Services

The SENTINEL-2 mission requirements for a twin-satellite, high revisit frequency, high resolution image will support Copernicus programmes. Observation data acquired from the SENTINEL-2 mission will be utilised by services such as:



The Copernicus Sentinel-2 mission comprises a constellation of two polar-orbiting satellites placed in the same sun-synchronous orbit, phased at 180° to each other. It aims at monitoring variability in land surface conditions, and its wide swath width (290 km) and high revisit time (10 days at the equator with one satellite, and 5 days with 2 satellites under cloud-free conditions which results in 2-3 days at mid-latitudes) will support monitoring of Earth’s surface changes.

This Sentinel-2 Mission Guide provides a high-level description of the mission objectives, satellite description and ground segment. It also addresses the related heritage missions, thematic areas and Copernicus services, orbit characteristics and coverage, instrument payload, and data products.

The Mission Guide categories are:

This section provides a brief description of the mission and the main thematic areas and services such as land monitoring and climate change.

Mission Objectives
Describes primary and secondary objectives of the Copernicus Sentinel-2 mission.

Satellite Description
Describes the satellite platform and the communication links, the main instrument of the Sentinel-2 mission, the MultiSpectral Instrument (MSI), as well as the orbit characteristics of the mission.

Ground Segment
Describes the Flight Operations Segment (FOS) and the Payload Data Ground Segment (PDGS) of the mission.

Data Products
Outlines the Level-1B, Level-1C and Level-2A data products that are available to users, including the Level-1C tiling grid.

Sentinel-2 infographic

To celebrate the recent five year anniversary of Copernicus Sentinel-2 – with the launch of Sentinel-2A on 23 June 2015 – we produced a special infographic on the mission. The infographic highlights important facts and achievements of the mission after its first five years of operations.