PARIS -- Surging to meet a launch date in October, engineers are working around the clock on Europe's first two operational Galileo navigation satellites to get the funding-plagued program off the ground.

Artist's concept of two Galileo in-orbit validation satellites. Credit: ESA
 
The satellites are being assembled and tested by Thales Alenia Space in Rome. The spacecraft should be shipped from Rome to the launch site in French Guiana in early September, according to a senior European Space Agency official familiar with the navigation program.

The top manager said engineers are working in three shifts seven days a week because there is "a very tight schedule" between now and launch, which is slated for Oct. 20 on the first Russian Soyuz rocket to blast off from the French-run Guiana Space Center in South America.

The readiness of the two spacecraft will determine the launch schedule. European and Russian engineers successfully tested the Soyuz rocket's new launch pad in French Guiana last month, and only minor work remains before officials declare the facility ready.

The Soyuz 2-1b rocket for the Galileo launch Oct. 20 will arrive in French Guiana from Russia in July.

Sandrine Bielecki, a spokesperson for Thales Alenia Space, confirmed teams are working 24 hours a day to meet the deadline on the satellite side.

"The first two satellites are in the final phases," Bielecki told Spaceflight Now. "As planned with ESA, both will be delivered within the first half of September."

Teams completed a systems test in late May linking the spacecraft with satellite control centers in Oberpfaffenhofen and Darmstadt in Germany and Toulouse, France. It was one of a series of integrated test campaigns, and another one is planned this summer.

The systems testing also included Galileo's navigation control center in Fucino, Italy, and elements of the ground receiver to be used by users of positioning and timing services.

"It's working well, so we are confident at the systems level," the ESA official, who requested anonymity, told Spaceflight Now in an interview.

Although the official said there are no significant issues with either of the first two Galileo in-orbit validation, or IOV, satellites being tested in Rome, there is still a tight schedule for liftoff in October.

"We are quite confident to have the launch on the 20th of October, but with very limited margin and a high level of effort in industry and in ESA at all levels in production, integration and administration," the official said.

The Galileo program is Europe's counterpart to the U.S. Air Force's Global Positioning System. Galileo will provide precise positioning, navigation and timing information to civilian and military users from a constellation eventually comprising 30 satellites.

There is no deadline for the IOV satellites to reach orbit and start transmitting navigation signals. A pair of experimental ESA satellites launched in 2005 and 2008 are still functioning, ensuring Europe retains control of the frequency spectrum needed for Galileo.

Artist's concept of the Galileo satellite constellation. Credit: ESA
 
The other two Galileo IOV satellites will launch in the middle of 2012 on another Soyuz rocket, but workers are scaling back efforts on those craft as they hurry to complete work on the first pair for liftoff this year.

The first batch of four Galileo satellites were designed by EADS Astrium and assembled by Thales Alenia Space. Each craft will weigh about 1,400 pounds at launch and will operate in an orbit more than 14,600 miles from Earth.

The next 14 Galileo satellites, built by OHB System of Germany, will start launching in late 2012 or early 2013. OHB's factory should produce about eight satellites per year, equating to about one Soyuz launch with Galileo payloads every three months.

"That's something we have not yet realized because at ESA, we do one-shot very complex satellites," the agency official said. "It goes to its operational life, then we move on to another program. Here we have to not only operate the satellites flying, but we will be in a permanent campaign spirit at least three years, which in terms of managing teams, both in industry and at ESA, is something we have to fine tune."

Ten of the next 14 satellites, called full operational capability, are on the books for a launch on the Soyuz rocket. The remaining four could be split among two additional Soyuz missions or fly together on a single Ariane 5 rocket flight.

Officials are already preparing to adapt the Ariane 5 rocket and its storable propellant upper stage for multi-hour Galileo delivery missions. ESA wants to keep the Ariane 5 as a backup to ensure Galileo satellites have access to space in the event of political or technical trouble with the Russian Soyuz program.

ESA also wants two satellite contractors to build the Galileo spacecraft, which is why the agency awarded the first four validation platforms to Astrium and Thales, while the next 14 craft went to OHB System.