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How Airbus Defence and Space can make things fly … on the ground

Simulation: the key to successful mission

You can’t take a spacecraft that needs to perform a docking manoeuvre while travelling at a speed of 28,000 km/hr for a test run, so how can you make sure that once it gets aloft it performs exactly as it needs to?

The answer is simulation – effectively executing an entire mission without leaving the cleanroom.

The ATV (Automated Transfer Vehicle), the Airbus Defence and Space-built cargo supply craft for the International Space Station (ISS), heading for rendez-vous

The ATV (Automated Transfer Vehicle), the Airbus Defence and Space-built cargo supply craft for the International Space Station (ISS), heading for rendez-vous

Take the example of the ATV (Automated Transfer Vehicle), the Airbus Defence and Space-built cargo supply craft for the International Space Station (ISS). It is the biggest, most complex spacecraft ever developed and built in Europe – an unmanned 20-tonne space freighter that once launched makes its own way up to the ISS where it performs a completely autonomous rendezvous and docking manoeuvre with a remarkable accuracy of only a few centimetres!

A simulation of the ATV in the final ISS approach phase

A simulation of the ATV in the final ISS approach phase

And there’s more. The ATV is not only the space vehicle itself, but a vast interconnected system: there are ground control centres in Toulouse (ATV mission control), Moscow (supervision of docking with the Russian Zvezda module on the ISS), and Houston (ISS mission control); the ISS astronaut crew also have an ATV control panel; a satellite network relays commands and data between the ATV, the ISS and the three control centres.

The ATV programme involves many companies from all over Europe, providing equipment and support services.

Airbus Defence and Space, industrial prime contractor for the programme, is responsible for ensuring that all this comes together to create a perfect whole, and works as smoothly as clockwork, during every single phase: integration, qualification, launch, ISS approach and docking, and through out the entire mission of the ATV, right up to the craft’s ultimate separation and controlled burn-up in the atmosphere.

100% mission-ready – because it’s all been done before

When the ATV sets off aboard its Ariane 5 launcher, everybody and everything must be 100% ready. Airbus Defence and Space uses a highly sophisticated Functional Simulation Facility (FSF) at its Les Mureaux site near Paris to ‘fly’ an exact mock-up of the ATV which houses nearly all the on-board electronic equipment through all the stages of a full virtual mission (first orbit injection, orbit transfer, rendezvous and docking, attached to the ISS, undocking and leaving the Station), checking out the complete system and previewing all possible nominal and ‘off-nominal’ scenarios. The FSF platform, with its hundreds of cables and umbilicals, dozens of ground computers, and controlled by some 50 engineers, replicates all aspects of the functional environment that the ATV will encounter. In the simulations, which are performed at ‘real’ speeds, it is as if the craft is actually flying in orbit. Myriad permutations enable all conceivable anomalies and failures to be virtually introduced into the scenarios to test out and plan for all eventualities.

Airbus Defence and Space’s qualification platform, the Functional Simulation Facility (FSF), combines simulation and real ATV parts

Airbus Defence and Space’s qualification platform, the Functional Simulation Facility (FSF), combines simulation and real ATV parts

The ATV mock-up that is used with the FSF does not look like the spacecraft that will take to the skies. The outer structure is dispensed with for these purposes, and the parts that constitute the ATV’s electronic ‘brain’ and ‘nervous system’ are connected up to the platform.

The platform models interfaces with the Ariane 5 launcher, the ISS, and with the ground and satellite communication network. Various modules delivered by industrial partners are also integrated. The core simulation software is installed and fine-tuned on more than 15 real-time simulation platforms – not just at the Les Mureaux site, but also in Moscow, Toulouse and Houston – some of which include real on-board computers and most of the real equipment to ensure electrical compatibility, flight software validation, system qualification and the development of integration procedures.

Supervision and test performance monitors on the Functional Simulation Facility (FSF) qualification platform for the ATV

Supervision and test performance monitors on the Functional Simulation Facility (FSF) qualification platform for the ATV

As well as the spacecraft, many of the human beings participating in the ATV programme are virtually put through their paces. Real-time numerical simulations are used for training the controllers at the ATV Control Centre in Toulouse and for large Joined Integrated Simulation (JIS) exercises with the other centres. Creating a common simulation over a secured pan-European network infrastructure and involving hundreds of operators, JIS links together the Toulouse (ATV control) and the Moscow (Russian ISS module) simulators, with the Houston (ISS control) centre also in the loop for the fullest, most representative simulation of the mission.

The ATV’s docking ‘nose’, the Docking and Refueling System (DRS) probe, attached to the FSF qualification platform

The ATV’s docking ‘nose’, the Docking and Refueling System (DRS) probe, attached to the FSF qualification platform

Simulations throughout the ATV lifecycle

This simulation activity is a major part of the preparation of the mission and mandatory for obtaining Flight Acceptance. From ATV design to vehicle integration tests and mission qualification, each phase of the lifecycle requires simulations. Once the ATV is in flight, simulation platforms support in-depth analysis in case of any anomaly and are used to validate new contingency procedures. At the end of the mission, after the ATV has re-entered the Earth’s atmosphere and safely disintegrated, simulations are a vital component of post-flight analysis … and then it’s time for the next ATV mission qualification campaign!

Simulation activity is a major part of the preparation of the mission

Simulation activity is a major part of the preparation of the mission

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