Satellite Simulators

Simulators are an indispensable tool for preparing satellite operations, training the satellite operators, and supporting daily operations during the life of the mission.


Terma has developed and maintained simulators for many years. Projects and equipment supported include

  • OBC Simulators
  • ExoMars2016
  • Sentinel-1A-D
  • Autonomous Transfer Vehicle (ATV)
  • Integral
  • Huygens
  • NDIU Lite.

In addition, Terma has been responsible for the development of the ESOC Simulation Infrastructure – SIMSAT – in the latest versions. SIMSAT is a real time simulation kernel.

In addition to SIMSAT being at the core of any operational simulator, Terma has also developed high performance emulators of the flight processors – these emulators are necessary to be able to run the real flight software in the Operational Simulator. The Terma emulators are based on the original ESOC emulator and offer higher performance and support of newer processors (ERC32, LEON2, LEON3, as well as ARM).

Terma has supported the Huygens mission with SIMSAT simulators (image courtesy: ESA - D. DUCROS)


Sentinel-1 (Image courtesy: ESA)

The purpose of an Operational Simulator is to provide a realistic simulation of the spacecraft, the ground segment and the space environment.

This is used by the satellite operator for a number of activities:

  • Testing and verification of the ground segment prior to launch of the spacecraft
  • Development of Flight Operations Procedures covering normal operations, contingency procedures and special operations (LEOP, eclipse etc)
  • Training of the Flight Control Team

It is necessary for the simulation to be very representative of the real environment and mirror rather accurately the functions of the spacecraft.

One important aspect of this is the need to run the real spacecraft flight software as part of the simulation environment using an emulator – and this is where use of Terma emulators can bring significant benefits such as running at many times real time performance.

The OBC Simulators are used both in operational simulators and Software Validation Facilities – used for development and testing of on board software.


A typical Operational Simulator is made up of:

  • Simulator kernel – this provides the scheduling, MMI, control interfaces etc
  • Emulator – to host the spacecraft flight software
  • Spacecraft Models – to simulate the various subsystems of the spacecraft (On Board Computer and Data Handling, AOCS, Communications, Thermal, Power, and Payload Models)
  • Ground Models to simulate the ground segment
  • Environment models
  • Dynamic models (for use wit he AOCS subsystem)

All simulators and models provided by Terma are SMP2/ECSS-SMP compliant, so can run in a variety of simulation kernels.

Envisat (image courtesy: ESA)