Europe's Galileo Flight Model #3 (FM3) satellite is undergoing checkout at the Spaceport in preparation for launch along with its "sister" FM4 co-passenger on Arianespace's next Soyuz mission from French Guiana, which is targeted for the second half of 2012.

Initial activity with FM3 in the Spaceport's S1B clean room facility includes propulsion sub-system testing and a fit check with hardware for the dual-satellite payload arrangement on Soyuz. It was delivered last week, arriving aboard a chartered cargo jetliner from Europe.

Galileo FM3 will soon be accompanied in French Guiana by the FM4 spacecraft, which together are to join another pair lofted by Arianespace on the medium-lift Soyuz launcher's maiden Spaceport flight in October 2011.

All four satellites are In-Orbit Validation platforms that will enable European industry to validate prototype Galileo-based receivers and services against actual satellite signals, while also allowing performance assessments of Galileo's ground system that serves to maintain the Galileo system's precision.

A European industry consortium led by the Astrium division of EADS and Thales Alenia Space have built the IOV spacecraft. The complete Galileo system will be composed of a 30-satellite constellation in orbit, creating an independent global satellite navigation system for Europe.

Galileo is a program initiative of the European Commission and European Space Agency (ESA), with each spacecraft carrying an optimized atomic clock for navigation and a powerful transmitter to broadcast precise navigation data worldwide.

Arianespace is responsible for deploying the entire Galileo constellation, beginning with the 2005 and 2008 launches of two experimental satellites - Giove-A and Giove-B - from Baikonur Cosmodrome in Kazakhstan by its Starsem affiliate.

This was followed last October by Arianespace's maiden Soyuz launch from French Guiana that carried the constellation's first two operational satellites. A mix of both Soyuz and Ariane 5 launchers will be used by Arianespace for the Galileo spacecraft, demonstrating the company's flexibility in orbiting satellite constellations.