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 for the duration of the Sentinel-3 commissioning phase, and during routine operations by EUMETSAT in Darmstadt Germany.

Sentinel-3 FOS   Sentinel-3 FOS

Figure 1: ESA's European Space Operations Centre (Left) and EUMESAT's Mission Control Center (Right)

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 tele-commands.

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 tele-command process.


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


Key Resources

Sentinel-3 Key Resources