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The European Space Agency’s (ESA) second pair of Galileo navigation satellites, Flight Model 3 (FM3) and Flight Model 4 (FM4), have been launched from the European Spaceport in French Guiana aboard a Soyuz ST-B VS03 rocket.

The two ‘in-orbit validation’ (IOV) satellites join the first two Galileo satellites that entered space in 2011.

The rocket’s Fregat-MT upper stage released the latest pair of Galileo satellites in opposite directions with the help of a pyrotechnic separation system that placed them into their orbits at 14,415 miles above the Earth.

These satellites were developed by a consortium led by Astrium as prime contractor, while Thales Alenia Space was responsible for assembly, integration and testing.

Operations of the satellites are managed by SpaceOpal, a joint venture between the DLR German Aerospace Center and Italy-based Telespazio, with initial operations controlled by a joint ESA and CNES French space agency team in France.

“Now that four Galileo satellites are in orbit, ESA will be able to determine the performance of their positioning systems thoroughly."

Following initial tests, the FM3 and FM4 satellites will be taken over by Galileo Control Centres in Germany and Italy to conduct further testing before they are commissioned for the Galileo service validation stage.

Now that four Galileo satellites are in orbit, ESA will be able to determine the performance of their positioning systems thoroughly.

Galileo is a programme initiative of the European Commission and the European Space Agency (ESA). Each Galileo spacecraft features an atomic clock for navigation and a powerful transmitter to enable precise broadcast of navigation data globally.

ESA has 18 satellites scheduled to be launched before the end of 2014. Galileo’s full operational capability (FOC) will be achieved in 2018 with 30 satellites.

Image: An artist’s impression of four Galileo ‘in-orbit validation’ satellites in medium-Earth orbit. Photo: courtesy of European Space Agency.