Sentinel-1 and Sentinel-3-OLCI PAC at DLR
Hahmann, Thomas; Weber, Hans; Diedrich, Erhard; Schreier, Gunter
German Aerospace Center (DLR), GERMANY

This abstract covers the project "Preparation and Operations of the Sentinel-1 and Sentinel-3 OLCI Off-line Processing and Archiving Centre at DLR Oberpfaffenhofen (S1-PAC / S3-OLCI-PAC)".

Mission Context: the GMES Architecture

Global Monitoring for Environment and Security (GMES / named Copernicus since December 2012) is an initiative led by the EU. The major GMES building blocks are: the Space Infrastructure, to be implemented by ESA with Sentinels, EO missions developed by ESA specifically for GMES; complemented by Contributing Missions, EO missions built for purposes other than GMES, but offering part of their capacity to GMES (EU/ESA Missions, EUMETSAT, commercial, international); the In-Situ Infrastructure, coordinated by the EEA; the Services Component in support of the large and diverse user community offering GMES Services coordinated by the EC and User (Downstream) Services, intended to be provided by commercial entities.

Sentinel Space and Payload Data Ground Segment (PDGS) Infrastructure

The Sentinel Space Infrastructure as central part of the GMES Architecture is composed of the Sentinel Space Segment and the Sentinel Ground Segment consisting of the Flight Operations Segment and the PDGS. The Sentinel Space Segment is composed of three series of two satellites each: Sentinel-1A/B satellites, each carrying a C-Band SAR to ensure the data continuity of ERS, Envisat, Radarsat; Sentinel-2A/B satellites equipped each with a 13-channel Multi-spectral Imager to provide enhanced continuity of SPOT- and Landsat-type data; Sentinel-3A/B satellites with several sensors (SLSTR, OLCI, SRAL) for ocean and land applications building on ERS-2 (AATSR), Envisat (MERIS), and Cryosat heritage technology. The Sentinel satellites are currently under development. In parallel, the development of the associated PDGS for each Sentinel is under way.

The Sentinel PDGS will consist of the following major constituents: 4 X-Band Core Ground Stations (CGS) to receive all Sentinel-1/2/3 payload data; 7 Processing and Archiving Centers (PAC); 3 Mission Performance Centres; a Data Circulation and Dissemination Network; a Mission Management, Monitoring and Control Centre; the Coordinated Data Access System (CDS). 4 CGSs (located in Norway, North America, Italy, Spain) will receive payload data in X-Band. Each CGS is able to receive data from all Sentinels. All CGS are offering NRT processing services. 7 PACs are located as follows: S-1 PAC (UK); S-1 PAC (DLR/Germany); 2 S-2 PACs (UK, Spain); S-3 OLCI-PAC (DLR/Germany); S-3 SLSTR + Synergy PAC (France); S-3 SRAL-PAC (France). The S1-PAC and the S3-OLCI-PAC are collocated at DLR's Earth Observation Center in Oberpfaffenhofen/Germany and are integrated, operated and maintained by an experienced team of experts from the DFD institute.

Sentinel-1 and Sentinel-3-OLCI PAC at DLR

DLR was selected by ESA for the role of a PAC operator of the Sentinel missions. High-level tasks of a PAC are: receive Sentinel data from CGSs via electronic link; ingest these data into the STA and MTA of the Sentinel PGDS; in addition ingest these data in a long-term archive (LTA) for a period of more than 7 years; perform consolidation and re-assembly of level-0 data received from CGS facilities; perform systematic and request-driven processing of Sentinel data to higher-level products; host Sentinel data products within a layered architecture of on-line dissemination elements that will facilitate the direct access of end-users via public networks; share and exchange any locally processed data with a 2nd partner PAC for the purpose of redundancy. According to the GCS operations concept the Sentinel PDGS will become operationally embedded in the GSCDA System that ESA implements in support of GMES Service Projects and their users.

Project Phases

The project is structured in a phased approach: The Site Preparation Phase (SPP) started at DLR in Sept. 2012. The Deployment and Test Phase (DTP) will start in Q2/2013. The Commissioning Operations Phase (COP) is expected to start mid-2014, whereas the Routine Operations Phase (ROP) will start around Q4/2014. The main technical tasks of the project phases are:

SPP: Rooms are prepared to host the Sentinel PDGS equipment. The LTA facilities room is prepared for the implementation of LTA upgrades. The LAN infrastructure concept is finalized. This phase ends with the Site Readiness Review at DLR to provide evidence that sites and associated infrastructure is ready for the deployment of the Sentinel PDGS.

DTP: Installation, configuration, and tuning of LAN hardware and software. Deployment of Sentinel PDGS hardware and installation of software, and staff training. Integration of the LTA with the PDGS. Support of the Sentinel Ground Segment Overall Validation. Demonstration of reprocessing capability with ESA provided test data sets. The DTP ends with the Operational Readiness Review at DLR to present all results of deployment and tests, to demonstrate end-to-end PAC operations based on complete procedures and documentation and a trained operations team. Systems / infrastructure shall be ready for Commissioning Operations.

COP: Support all satellite commissioning operations. Perform all Sentinel PAC functions and monitor service performance. The COP ends with the Routine Operations Readiness Review with the objective to demonstrate readiness of the DLR PAC to undertake the routine operations.

ROP: The operating services are Network Services, LTA Service, Production and Dissemination Service, and Support Operations. The LAN infrastructure is operated in terms of a managed service. The LTA Service covers: Systematic ingestion of Sentinel data from the Sentinel PDGS; retrieval of archived data products for the dissemination to end-users on request of ESA; bulk retrieval of data to be used as input for reprocessing activities; systematic ingestion of data generated in the context of reprocessing campaigns; LTA maintenance activities (e.g. archive monitoring, archive refreshment). The Production and Dissemination Service covers systematic / on-request processing and generation of Sentinel data products of all levels; transfer of received and processed data into STA, MTA, LTA; circulation of data products to partner centers via the multi-Sentinel WAN; Dissemination of data products to Sentinel end-users.

Enhancements of DLR's existing LTA

As of 2013 DLR will have a robotic storage library available that will be able to manage 10,000 storage slots. The storage tape technology to be utilized is the new T10000C tape drive standard of Oracle through which it is possible to store up to 5 TB of data natively on one single cartridge. DLR's tape archive will be able to host 50 PB of data. DLR expects the following capacity requirements per year: approx. 1076 TB for S-1A data products; approx. 238 TB for S-3A OLCI nominal data products.