PARIS, Dec. 13 (Xinhua) -- Europe launched four more Galileo navigation satellites on an Ariane 5 rocket Tuesday, bringing its navigation system just one step away from completion next year, the European Space Agency (ESA) said.
The rocket carrying Galileo satellites 19-22 was operated by satellite launch company Arianespace under contract to the ESA. It lifted off from Europe's Spaceport in Kourou, French Guiana in South America, at 1836 GMT.
The four satellites will be steered into their final working orbits in the coming days to undergo around six months of tests, the ESA said.
The mission brings the Galileo constellation to 22 satellites. The system began to provide navigation services on Dec. 15, 2016.
The next launch with four more satellites in mid-2018 will bring the constellation to the point of completion with 24 satellites, plus two orbital spares.
Galileo is Europe's civil global satellite navigation system enabling users worldwide to know their exact position in time and space.