Airbus Defence and Space

Getting the satellites to fly

Up to 1998, telecommunications satellites were delivered to their geostationary orbit and validated by the space agencies (CNES, DLR, etc.).

"When Airbus Defence and Space won the Nilesat contract in 1995, we decided to move up a step in the control of our telecommunications satellites, and handle delivery of our satellites on station ourselves,” explains Jean-François Poussin, chief telecommunications engineer and initiator of the project with Philippe Grémillon. "As industrial leader in the space domain, we had to be capable of providing in-orbit delivery and handover of the satellite to our customer under ‘turnkey’ conditions, so as to be able to position ourselves in this increasingly competitive market." This capability was also a logical extension of our in-orbit support activity in case of satellite non-conformance, which had already been set up for Hispasat in 1992.

The LEOP control centre (T-SOC) has been located on the first floor of the Toulouse site’s building D since 2001. In 2008 it was upgraded to deal with ever increasing telecommunications satellite launch requirements. Order intake has been particularly good for telecommunications satellites over the last two years, and our in-orbit delivery capability has now been doubled with the creation of a second control centre to enable us to monitor two satellite launches simultaneously. Antoine Poulet, in charge of all LEOP activities, explains: "In the next three years, we shall be launching between four and five satellites per year, compared with an annual rate of two to three satellites since 2004. It was therefore absolutely essential to move with the times in order to honour our commitments to our customers."

As François Gaullier, in charge of the LEOP operations teams, puts it: "This service also forms part of the rationale for supplying ever better technical support to our customers, with guaranteed reliability for execution of the in-orbit mission. This also gives us hands-on experience of satellites’ in-orbit behaviour and secures our incentives, namely the fees paid by the customer during the years of operation of the satellite in orbit. The T-SOC teams support our customers as required, and have access to Eurostar experts via a 24/7 on-call system. A backup control centre makes it possible to assure continuity of service, and conduct in-orbit support for our customers."

For all these activities, the T-SOC operational team has all the experts who designed the Eurostar platform directly on hand, thus ensuring maximum efficiency and safety during operations. If an unscheduled event occurs, it is thus possible to carry out investigations very rapidly, and maintain control of the satellite in accordance with dedicated procedures, which only the designers of the satellite can implement in such a short space of time.

Experience demonstrates the operational and financial advantage of having this resource immediately accessible to the designers, and ensures rapid reaction, reduced costs and maximum safety.

In-orbit delivery (IOD) – A rough guide


 

The delivery phase commences at the moment when the satellite separates from the launcher. This is when the LEOP teams take control. For 10 days, between 30 and 40 specialists work shifts around-the-clock, to ensure the satellite is correctly delivered to geostationary orbit. They then monitor and control the satellite for a period of one month up to its final qualification, the final step before ’handing over the keys’ to the customer.

At the actual moment of launch, all members of the team have their eyes glued to their screens, waiting for the first ‘squeak’ from the satellite. Making contact is the initial step in the process. The control centre must be hooked up to a network of ground stations located around the world for this purpose, so as to be able to acquire the satellite, irrespective of its position round the globe, during the initial phases of the mission.

When the first signal is picked up, the control centre can then monitor initialisation operations for the satellite sub-systems (attitude control, power, propulsion, etc.). Once the satellite is in cruise mode, the control centre can commence orbit circularisation. This involves positioning the satellite in geostationary orbit at an altitude of 36,000 km, with three or four apogee motor firings, calculated and optimised by the orbit specialists in the Flight Dynamics teams.

Once the geostationary orbit has been acquired after around six to eight days, deployment of the solar panels and antenna reflectors can begin. This phase takes between one and two days. The last step is final Earth acquisition, at which time the satellite is pointed at the Earth so as to be able to receive and transmit operational signals. This concludes the orbit acquisition process lasting about ten days post-launch. All that remains is for the satellite to acquire its operational longitude, and for the LEOP teams to validate its satisfactory operation.

The in-orbit test (IOT) phase can then commence, and is conducted in two parts. The first part is to verify satisfactory operation of the platform (platform IOT), and is conducted by the LEOP team. These tests are executed while the satellite drifts towards its final longitude. The second part is payload testing (payload IOT), and is usually directed from the customer’s premises with on-site support from Airbus Defence and Space engineers. The Toulouse LEOP centre remains on standby, ready to take over control of the satellite at any time if an abnormal situation develops. About 20 days are usually required to complete all in-orbit tests and make final, official delivery of the satellite to the customer.

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