August 19, 2016

Ground segment

Ground Segment and Operational Concept

CNES is prime contractor for the ground segment and develops all its components which will be operated by several entities:

PLEIADES Ground segment

SPOT Image serves civilian clients.

  • Users can consult the civilian image catalogue, submit requests and receive the ordered products.
  • All civilian programming requests are centralized by SPOT Image.
  • SPOT Image insures the civilian antenna management as well as the reception and the archiving of raw data received from satellites.
  • Raw images are processed on request, in order to generate the different system products.
  • SPOT Image updates a main catalogue gathering all civilian data acquired by satellites.
  • SPOT Image also manages a network of regional image receiving stations (RIRS). The Kiruna station enables to receive daily the Pleaides images, in complement of the Toulouse station; it is managed as a RIRS.

The Defence Mission Centres (French and Spanish) serve the defence users of each country. The basic functions of the Defence Mission Centres are similar to those of the civilian ground segment with some differences in the interfaces and the security.

CNES hosts the dual control centre (civilian and military). This control centre has several functions:

  • It insures the daily management of the satellite, by receiving the telemetry enabling to verify the good health of the satellites, and by uploading all the commands necessary for its mission.
  • It hosts the defence coordination function, which enables to propose an optimized work plan to the different partners, taking into account as best as possible the priorities of each national work plan.
  • It plans of all the programming requests by collecting all civilian and defence users' requests.
  • It ensures the satellite and its instrument calibration function, for the benefit of all the users.

The PLEIADES dual control centre (SDGC)

The PLEIADES dual programming centre (DUPC) ensures the dual use of the programming resources in a national and international cooperation context. The DUPC is mainly in charge of:

  • the production of the command plans for the mission following the resource sharing rules, and the respect of the confidentiality and defence priorities,
  • the production of the X band antennas reception plans and the Pleiades image processing inventory plans,
  • the production of the PLEIADES retrieved attitude data to supply to the image processing services.

The satellite Command-Control Centre (CCC) directs the launch operations of the PLEIADES constellation to achieve the objectives of the mission plan. It ensures the following functions:

  • production of the satellite telecommands (TC) including the mission command plan from the DUPC,
  • transmission of the TC to the Telecommands, Telemetry and Control ground stations (TT&C) for the satellites of the constellation,
  • reception of the housekeeping telemetry in the TT&C ground stations and decommutation at the CCC,
  • monitoring of the satellites' good health,
  • preparation of the command procedures; compilation of the operations data base,
  • management of the flight software programmes and uploading to the satellite,
  • determination and prediction of the orbit and the attitude, SCAO management.

The image quality centre ensures the calibration of the PLEAIDES satellite and its instrument:

  • It implements the calibration procedures and elaborates the calibration parameters of the PLEIADES instrument.
  • It supplies the calibration parameters to the PLEIADES processing ground segments.
  • It verifies the PHR instrument performances by evaluating the image quality.

This centre distributes the calibration data to all image processing services (for Defence, this distribution is made via the DUPC for security reasons).

Pleiades-HR French civilian ground segment

The Pleiades-HR French civilian ground segment serves the civilian clients (commercial or institutional) at national or international level. Its functions include:

  • the interface with users all around the world. The users can consult the civilian image catalogue, submit requests and receive the ordered products,
  • the centralization of all the civilian programming requests for all civilian users; the long term planning of civilian requests,
  • the management of civilian antenna, the raw data reception, the verification, formatting, and backup,
  • the unity of the PLEIADES image processing to generate system products as well as the archiving,
  • a main catalogue of all civilian data from the PLEIADES satellites,
  • interfaces to federated operational systems (civilians),
  • the access to PLEIADES regional image receiving stations including those located in Kiruna, and possibly in Matera for institutional users.

The French defence user ground segment

The basic functions of the French defence user ground segment are similar to those of the civilian ground segment with some differences in the interfaces, the security and additional possibilities, such as an autonomous programming management and an international coordination, which is made through a PLEIADES military programming and coordination entity. The PLEIADES services installed in this centre can be operated as independent or federated centre by the French defence operational ground segment.

Image Receiving Stations

The main stations are:

  • Toulouse (France) for French civilian ground segment users,
  • Creil (France) for French defence ground segment users,
  • Pratica di Mare (Italy) for Italian defence ground segment users,
  • Kiruna (Sweden) linked to the French civilian ground segment.

Moreover, the Kiruna station can be use in case of emergency to receive very urgent institutional civilian data and transmit them to the French civilian ground segment where they would be processed.