Brussels: Two European Galileo satellites launched as part of a navigation system designed to rival GPS have failed to locate their intended orbit, launch firm Arianespace said on Saturday.
The European Space Agency said an investigation had been launched into what it said were "the anomalies of the orbit injection" but that the satellites were being safely controlled.
The satellites Doresa and Milena took off from the Kourou space centre in French Guiana aboard a Russian-made rocket on Friday after a 24-hour delay because of poor weather.
"Observations taken after the separation of the satellites from the Soyuz VS09 (rocket) for the Galileo Mission show a gap between the orbit achieved and that which was planned," the Arianespace said in a statement.
"They have been placed on a lower orbit than expected. The teams of industries and agencies involved in the early operations of the satellites are investigating the potential implications on the mission," it said.
The 5.4 billion euro ($7.2 billion) Galileo constellation is designed as an alternative to the existing US Global Positioning System (GPS) and Russia's Glonass, and will have search-and-rescue capabilities.
Jean-Yves Le Gall, France's Galileo coordinator, said it would be "complicated" to correct the orbit of the two satellites.
"We are trying to see if we can remedy the situation in the coming hours," he said.
The European Space Agency said both the satellites were being "safely controlled" from its operations centre in Germany.
Initially, Arianespace had said that the satellites had separated from the mothership to enter into free-flight orbit as planned just under four hours after launch.
"These two satellites are the first of a new type of satellite that are fully owned by the EU, a step towards a fully fledged European-owned satellite navigation system," the European Commission, which funds the project, said.
Four Galileo satellites have been launched previously -- one pair in October 2011 and another a year later.
They are the nucleus of the constellation orbiting Earth at an altitude of 23,500 kilometres (14,600 miles), and will later be brought to full operational capability.
The launch of the latest pair, named by two European schoolchildren who won a drawing competition, had been delayed for over a year due to what the ESA described as "technical difficulties in the setting up of the production line and test tools".
Arianespace said Thursday it had signed a deal with the ESA to launch 12 more satellites from 2015 onwards. In March last year, the agency announced the first four test satellites had passed a milestone by pinpointing their first ground location.