Tuesday, 14 October 2014

Independent Enquiry Board announces causes for failed Galileo Launch

Last week, the Independent Inquiry Board (“the Board”), entrusted with the task to examine the exact causes that led to the orbital injection anomaly of Galileo satellites 5 and 6 on August 22, announced its definite conclusions. The Board reported that the anomaly occurred during the flight of the launcher’s fourth stage, the Fregat. Its main cause was a deficiency in the system thermal analysis performed during the design stage.

On August 22, in French Guinea a Soyuz rocket lifted off with two Galileo satellites. As it has been reported, after the separation of the Fregat upper stage, an anomaly caused the satellites to be injected into an incorrect orbit. To this effect, Arianespace, the Galileo launch services provider, set up the Board with the participation of experts of the European Commission and of the European Space Agency, to study the roots of the problem and provide recommendations on corrective measures.

According to a press release of Arianespace, the Board concluded that the primary cause of the anomaly was a design ambiguity in the system thermal analysis, and not an operator error during stage assembly. The Board found that no abnormal behavior of the Galileo satellites occurred. It also confirmed that the first part of the mission proceeded nominally; hence, the three-stage Soyuz launcher was not at fault. The Board identified the problem at the pipe that delivered the necessary hydrazine to the thrusters, which help the Fregat upper stage to be aligned for correct orbital injection. This pipe was frozen, because it was near the cold helium feed lines, which led to a heat transfer between the two (thermal bridge). The frozen pipe led to the freezing of the hydrazine.

The Enquiry Commission provided the following recommendations for corrective measures: (1) revamp the system thermal analysis, (2) make associated corrections in the design documents, and (3) modify the documents for the procedures on manufacture, assembly, integration and inspection of the supply lines.

As it has been reported by Arianespace, the manufacturer of the launcher’s fourth stage (NPO Lavotchkine) can easily implement these measures, which allows to go ahead with the next Galileo launch as from December 2014. The satellites 5 and 6 are in a stable position and safely controlled by the European Space Agency (ESA), while ESA is elaborating possible scenarios for the future use of the satellites.

It is also noteworthy that the European Commission and ESA have chosen not to obtain satellite launch insurance. They preferred to invest in spares and launch services instead. The latest launch, however, changes the scenario and the Galileo players may be forced to reassess their decision

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