The contract, signed Monday during the Paris Air Show in Le Bourget, France, calls for the satellites to be launched from Europe Space Agency's spaceport in French Guiana.
The ESA said the signing of the contract marks an important milestone for the Galileo program as it progresses towards the operational deployment of the Galileo satellite navigation system.
The four satellites to be launched from French Guiana will be placed into a circular orbit at an altitude of 14,665 miles by the end of 2010, the space agency said.
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