Alba and Oriana go to orbit: Arianespace ready to launch Europe’s next pair of Galileo satellites
Arianespace is gearing up to launch the European Galileo 9 and 10 satellites, named Alba and Oriana, on the company’s eighth mission in 2015, designated Flight VS12. Liftoff is scheduled to occur at 10:08 p.m. EDT on Thursday, Sept. 10 (02:08 GMT on Sept. 11) from the Soyuz Launch Complex (ELS) in Sinnamary, French Guiana.
The satellites are slated to be delivered into a circular medium-Earth orbit (MEO), at an altitude of 14,615 miles (23,521 km) and an inclination of 57.4 degrees, using the Russian Soyuz ST-B launcher.
This will be the fifth Galileo launch, set to bring the number of satellites in the Galileo global navigation system up to 10. The launch vehicle will be carrying a total payload of some 1.6 metric tons, including 1.43 metric tons for the two spacecraft. Two more satellites are planned to be launched by year’s end.
Galileo is a European project for a new global satellite navigation system, carried out on behalf of the European Commission, under a contract with the European Space Agency (ESA). Under civilian control, Galileo is planned to deliver high-precision positioning services.
The current Galileo 9 and 10 FOC (Full Operational Capacity) satellites are planned to be operational for more than 12 years, and are built by Bremen-based (Germany) OHB System as the prime contractor, with their navigation elements provided by Surrey Satellite Technology Ltd., UK, a 99 percent-owned subsidiary of Airbus Defence and Space. The two spacecraft to be orbited by Arianespace on Flight VS12 will be the fifth and sixth OHB-built satellites. Each satellite is named after one of the children who won a painting competition organized by the European Commission in 2011.
“Four satellites from OHB are already in space and have demonstrated their functional capabilities and their full performance,” said Ingo Engeln, a member of OHB System AG’s Management Board.
“[…] and we are well within schedule for the rest of the satellites. In Bremen, we are working at up to seven manufacturing stations in parallel during the production of the modularly structured satellites. In this way we can build two satellites in the course of three months,” he added.
During the mission, the ascent to space should last just slightly more than nine minutes, after which the rocket’s Fregat upper stage will fire twice to place the satellites into their release orbit. The Galileo satellites will separate from the Soyuz launch vehicle 3 hours and 48 minutes after lift off. The three lower stages and payload fairing will then fall back into the sea.
“Upon separation, the team will be very focused, and we’ll be watching for a number of critical events on the satellites to happen automatically at the right time and in the right order,” said ESA’s Liviu Stefanov, lead flight director for this phase.
“The satellite must switch on, go into a basic flight configuration, deploy its solar wings for power, orient them towards the Sun and acquire Sun-pointing attitude,” Stefanov said.
At the end of the mission, the Fregat upper stage will be activated. The two Galileo satellites will then lower their altitude in order to reach their operational orbit.
Tomorrow’s planned mission began with the arrival of the satellites in French Guiana on July 24 of this year. At the end of August, the spacecraft were fueled and attached to the dispenser that will hold them during their flight “uphill”. They were then attached to the Fregat upper stage and encapsulated within the launcher’s fairing.
The current launch campaign marks the first use of a new fueling facility at the European spaceport. Called FCube, short for Fregat Fueling Facility, the building was constructed to pump hydrazine and nitrogen tetroxide propellants into the Fregat upper stage.
The Soyuz rocket was rolled out to the launch zone on Monday, Sept. 7, in the Spaceport’s northwestern sector near the city of Sinnamary, followed by its raising to the vertical position and suspension over the launch pad. After the mobile gantry was moved in to protect the booster, the mission’s Fregat upper stage, the two dispenser-mounted Galileo satellites, and payload fairing were hoisted and mated atop Soyuz.
The Launch Readiness Review (LRR) is scheduled to take place on Wednesday, Sept. 9, to authorize the start of operations for the final countdown.
“The entire team is very motivated and we are ready for the next Galileo launch,” said Paolo Ferri, ESA’s Head of Mission Operations.
The version of Soyuz currently offered by Arianespace is a four-stage launch vehicle which includes the following: four boosters (first stage), a central core (second stage), third stage, and a restartable Fregat upper stage (fourth stage). It also includes a payload adapter/dispenser and fairing.
The booster’s RD-107A engines are fueled by kerosene with liquid oxygen as the oxidizer; the same propellants are used on each of the lower three stages. Following liftoff, the boosters burn for approximately 118 seconds and are then jettisoned. Thrust is transferred to the vehicle through a ball joint located at the top of the conical structure of the booster, which is attached to the central core by two rear struts.
The central core is similar in construction to the four boosters, with a special shape to accommodate the boosters. A stiffening ring is located at the interface between the boosters and the core. This stage is fitted with an RD-108A engine, also comprising four combustion chambers and four nozzles.
Ignition of the third stage’s engine occurs approximately two seconds before shutdown of the central core engine. The third stage engine’s thrust enables the stage to separate directly from the central core. The third stage uses an RD-0124 engine in the ST-B version.
The Fregat upper stage is an autonomous and flexible stage that is designed to operate as an orbital vehicle. It extends the capability of the Soyuz launcher, now covering a full range of orbits. To ensure high reliability for the Fregat stage from the outset, various flight-proven subsystems and components from previous spacecraft and rockets are used. The upper stage consists of six spherical tanks (four for propellants, two for avionics) arranged in a circle and welded together.
The first Galileo 1 and 2 satellites were launched atop a Soyuz rocket on Oct. 21, 2011. The latest satellites to be sent aloft (7 and 8) in the series were successfully orbited on March 27, 2015. Thursday’s flight will be the 12th Soyuz launch from the Guiana Space Center.
Video courtesy of Arianespace
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