Developed as part of a European Space Agency (ESA) programme to add a medium-lift launch vehicle to complement the light-lift Vega and heavy-lift Ariane 5 rockets.

[6] A collaborative effort between Russia and Europe, the project involved constructing the Ensemble de Lancement Soyouz (ELS; lit.

Additionally, the introduction of the Vega C and Ariane 6 launchers, both offering medium-lift capabilities, rendered the role of Soyuz largely redundant.

Several days before launch, a dedicated transporter moves the assembled Soyuz stages from the LVI Building to the launchpad.

Finally, approximately one hour before launch commences, the mobile service tower is meticulously retracted, readying the Soyuz for its mission.

[9][10][11][12][13] The first contract for the launch of Soyuz the CSG was signed at the 2009 Paris Air Show by the Director of the Galileo Programme and Navigation-related Activities René Oosterlinck and a CEO of Arianespace Jean-Yves Le Gall.

[20] The launch was planned for 20 October 2011, however an anomaly was detected in the pneumatic system responsible for disconnecting the fuel lines from Soyuz third stage, forcing the mission to be postponed for 24 hours.

[23] The mission appeared to proceed normally and Arianespace reported the launch to be a success, however analysis of telemetry data provided by ESA and CNES tracking stations showed that the satellites were injected into an incorrect orbit.

At the end of the re-orientation phase the flight control system detected an incorrect angular speed and unsuccessfully attempted to use thrusters to correct the situation.

[28] In late September 2014, the Roscosmos commission report, quoted by Izvestia, indicated that the Fregat failure was due to a design flaw leading to freezing in one of the hydrazine propellant lines, which was placed alongside a line carrying cold helium used for pressurization of the main propellant tanks.

During the long first burn required for Galileo orbital insertion the propellant line was cooled to below the freezing point of hydrazine.

[29][30] On 7 October 2014, the Independent Inquiry Board announced the conclusions of its investigation, revealing that a proximity of helium and hydrazine feed lines resulted in a thermal bridge that caused an interruption of propellant supply to the thrusters.