Two Galileo satellites were placed into orbit for Europe's global positioning system, space officials said.

A Soyuz rocket carrying the satellites successfully blasted off from the Sinnamary launch pad at the Kourou space base in French Guiana, at 3:15 pm local time (20:15 CEST), Friday.

After more than three hours of flight, the two Galileo satellites were placed into orbit. Both satellites joined the other two satellites that were launched on Oct. 11. Galileo is an initiative by the European Space Agency (ESA) and the European Union (EU) to create their own version of the Global Positioning System (GPS) and to be independent of the U.S. government controlled GPS system. Galileo will be Europe's own global navigational system.

The two satellites joined the other two in orbit forming a mini constellation to complete the validation phase of the Galileo program. Space researchers can now test the system extensively for their performance before they become fully operational.

A minimum of four satellites are required to get signals for a vehicle or a smartphone to calculate the navigational fix on the ground, reported BBC.

"Of course, these four satellites will be visible [only] during intermediate periods of time," Marco Falcone, the head of Galileo System Services at the European Space Agency (Esa), which is procuring the sat-nav network for the European Commission, told the BBC.

"But from now on, receiver manufacturers will be able to start testing the system and preparing for Galileo services," he said.

ESA is planning for a 30-satellite constellation (six satellites more than the U.S. GPS) to be completely operational by 2020. Eighteen satellites will be placed into orbit by late 2014 to offer early services to the public.

The system promises accurate positional fixes compared to the U.S. version of the GPS. According to a Reuters report, the cost of the satellite system is estimated to be around $25.9 billion (20 billion euros).