ESA is the contracting authority for the whole program.
Astrium (Toulouse) designed and built the satellite (platform and payload).
The control and mission centre is under ESA responsibility (ESOC in Darmstadt)
The scientific data processing is entrusted to the scientific community: laboratories, observatories, universities, and European agencies that wanted to be involved in the scientific processing of Gaia data have been grouped in a consortium–the Gaia DPAC (Data Processing and Analysis Consortium)–officially constituted in May 2006. This consortium is organized in nine "Coordination Units" (CU): the CU1 ensures system architecture, the CU2 ensures data simulation, the CU3 split the processing among its eight units, and the CU9–to be set up at the beginning of 2013–is responsible for the production of the final catalogue. Each CU is based upon Data Processing Centres (DPC) which ensure the technical coordination of the scientific software developments and their operational deployment.
By request of the scientific community, CNES is highly involved in DPAC for the architecture of the global system (CU1) and as processing centre for:
- The "Simulation" unit (CU2). Two of the simulators (GIBIS and GOG) are deployed at CNES as an online service accessible to the entire Gaia community using the joint resources of the CNES computing centre.
- The "spectroscopic processing" (CU6), "objects processing" (CU4), and "astrophysical parameters" (CU8) units. As such, it is in charge of the architecture, quality assurance, and engineering of the software sub-systems developed by these units. It also ensures the integration and qualification of these sub-systems on the resources of the computing centre at the Toulouse Space Centre.
Making hundreds of scientists from all over Europe work together requires an exceptional organization. DPAC has achieved it by elaborating common methods and standards (JAVA language, standard documents, configuration management tools with shared access, etc.), supported by collaborative engineering software programmes coming from the free software world widely used by ESA–Wiki, document management with Livelink, technical fact management with Mantis, and configuration management with Subversion. All this has already been set up, works well and has been accepted with goodwill by the scientists of this programme; the required effort to grasp these new tools and methods has been justified by the scope of the project and especially by the expected results.