Galileo Satellites Topped off for Sept. 10 Launch

UPDATED 08/28/15 with information from the European Space Agency.

Europe’s ninth and tenth Galileo satellites were fueled Aug. 24 by technicians in protective SCAPE suits within the Guiana Space Centre’s 3SB preparation building. This left the satellites ready to be attached to their launcher upper stage in preparation for launch. (Photo:ESA)

The two European Galileo navigation satellites for Arianespace’s next mission from French Guiana have been fueled at the Spaceport, readying them for integration with their Soyuz launcher.

Galileo full operational capability (FOC) satellites 9 and 10 were “topped off” during activity this week at the Spaceport’s S3B payload preparation facility, further advancing preparations for the Sept. 10 mission — which is designated Flight VS12 in Arianespace’s launcher family numbering system, signifying the 12th liftoff of the medium-lift Soyuz vehicle from French Guiana. Lift-off is scheduled for 02:08:10 p.m. UTC.

Flight VS12’s satellites are the fifth and sixth in Galileo’s FOC phase. They were produced by OHB System, with Surrey Satellite Technology Ltd. supplying their navigation payloads that will generate precise positioning measurements and services around the world.

The Sept. 10 mission will be the fifth Soyuz flight with Galileo satellites performed by Arianespace from French Guiana — a series that began with the Russian-built launcher’s inaugural liftoff at the Spaceport in Oct. 2011.

At full deployment, the Galileo program will consist of 30 satellites — comprising operational spacecraft and reserves — situated on three circular medium Earth orbits at some 23,200 km. altitude inclined 56 degrees to the equator. The constellation — and associated ground infrastructure — will provide high-quality positioning, navigation and timing services under civilian control, and be interoperable with GPS and the Russian GLONASS.

Galileo’s FOC phase is managed and funded by the European Commission, with the European Space Agency delegated as the design and procurement agent on the commission’s behalf.

Arianespace Flight VS12 will be the company’s eighth mission this year, following the successful launches in 2015 of four heavy-lift Ariane 5s, two lightweight Vega vehicles, and one Soyuz.

Technicians donned spacesuit-like SCAPE (Self Contained Atmospheric Protective Ensemble) suits to fill each satellite with sufficient hydrazine fuel for their planned 12 years of operations in space, the European Space Agency describes in a news release. This fuel is needed for fine-tuning of their orbital paths following their launch, followed by routine orbital and attitude control over the course of their working lives.

Each Galileo satellite needs to keep its navigation antenna trained on Earth’s disc at all times, employing dedicated infrared Earth and Sun sensors for this purpose. This marked the first time Galileo had been fuelled within the Guiana Space Centre’s 3SB preparation building. Previously, the S5 fuelling building was dedicated to this purpose, but upgrades by Arianespace mean fuelling can now take place at the same location where they will subsequently be attached to their Fregat upper stage, streamlining the satellite preparation process. Completion of fuelling means the two satellites are essentially ready for launch — what needs to be accomplished now is to first attach the Galileos to their launch dispenser, then to fix this in turn to their Fregat.

The satellites plus Fregat will then be encapsulated within the launcher fairing, after which this ‘upper composite’ can then be attached to the other three stages of the Soyuz ST-B launcher. The latest Galileo launch campaign commenced at the end of July, with the arrival of the satellites in French Guiana on July 24. A “fit check” followed, to confirm the satellites as delivered in Kourou did indeed fit onto the dispenser that will first secure them in place during launch and then pyrotechnically eject them into their orbits once their target 23 222 km altitude medium-Earth orbit has been reached. This was followed by in-depth system checks and final settings of onboard navigation and data handling software parameters.

Two further Galileo satellites are still scheduled for launch by end of this year. One of these satellites is completing testing at ESA’s ESTEC technical centre in Noordwijk, the Netherlands, while the other one has already completed its testing and is awaiting transportation to Kourou in the second half of October.

In addition the first satellite of the following batch has arrived at ESTEC and is currently undergoing its thermal vacuum test. Another flight model will arrive at ESTEC by mid-September.

Fueling Galileo 9 and 10.(Photo:ESA)