To operate the Sentinel missions, ESA developed a dedicated ground segment which includes:
- Sentinel Flight Operations Segment (FOS);
- Sentinel Payload Data Ground Segments (PDGS) comprising:
- Core Ground Stations (CGS) for Data Acquisition and product generation in Near Real Time: Matera (eGeos, IT), Svalbard (K-Sat, NO), Maspalomas (Inta, SP), Alaska (K-Sat, NO);
- Sentinel Processing and Archiving Centres (PAC): S1 (Astrium/UK, DLR/DE), S2 (Astrium/UK, Indra/SP), S3 (OLCI Land DLR/DE, SRAL CLS/FR, SLSTR-SYN ACRI/FR), S3 (OLCI Marine EUMETSAT/DE);
- Sentinel Missions Performance Centres (MPC): S1 (CLS/FR), S2 (CS/FR), S3 (ACRI/FR);
- Sentinel Precise Orbit Determination (POD);
- Payload Data Management Centre (PDMC) which is common to all Sentinels (ESRIN). It hosts the CSC Data Access system (CSCDA).
The volume generated by the ESA ground segment will reach in routine phase about 13 Tb/day.
The European Space Agency is setting up a distribution network for each user family:
- a private access to Copernicus services;
- an access without guaranteed performance for scientific and "other" users, the latter groups all users' categories, including the commercial sector. International and national mirror sites in Europe could complement this access;
- an access for international users through international mirror sites (for example hub based in the United States ;
- an access through national mirror sites for users located in UE and ESA Member States (collaborative projects, R&D projects funded by ESA).
Colour code of the CSC Data Access layer: in blue the hubs under responsibility/funding of the European Commission and technically set up by ESA, and in orange the hub under ESA responsibility.
ESA's hubs should contain a rolling archive from 1 to 3 months. Each hub will have a user interface based on the same architecture (Data Hub User Service) enabling to consult the catalogue, select and download products.
The dissemination system is complemented by national mirror sites set up in the "Collaborative Ground Segments" framework. Several countries (including Germany, Italy, the United Kingdom, Greece, Finland) are already involved in this process. France is developing its own mirror site: PEPS (Platform for Exploiting Products from Sentinels). Overall, ESA has identified a dozen proposals for national and local mirror sites.
The national mirror sites have a unique access right (only one registered user per country) to a dedicated hub which will offer the required performances at server level. The link between the mirror site and ESA's hub (Wide Area Network) remains under the responsibility of the Member State.
CNES is ESA's national contact point for all the collaborative initiatives in France. As such, it will receive the unique access right to ESA's hub. In practice, a European user, collaborative or not, will have two possibilities to access Sentinel data: through internet using ESA's hub dedicated to the "scientists or other" users or through the mirror site when it exists. A third (limited) way is possible: through a local receiving station (only for Sentinel-1 data acquired in the station's visibility circle).