Two More Galileo Satellites Scheduled for August 21 Launch

August 14, 2014 - By GPS World Staff

Artist’s rendering of an OHB-designed Galileo satellite. OHB in Germany and SSTL in the UK are building the next 14 Galileo satellites.

UDPATE:

After a one-day postponement, The fifth and sixth Galileo satellites were successfully launched and deployed.

UPDATE:

Arianespace has decided to postpone the launch of Soyuz flight VS09 carrying Europe’s fifth and sixth Galileo satellites, because of unfavorable weather conditions over the Guiana Space Centre.

Another launch date will be decided depending on the evolution of the weather conditions in Kourou.

The next satellites in Europe’s Galileo satellite navigation system will be launched on August 21, ushering in the system deployment phase and paving the way for the start of initial services, according to the European Space Agency (ESA).

Galileo SATs 5-6 are scheduled to lift off at 12:31 GMT (14:31 CEST, 09:31 local time) August 21 from Europe’s Spaceport in French Guiana on top of a Soyuz rocket. They are expected to become operational, after initial in-orbit testing, in autumn.

The launch can be watched live here.

The two satellites will join the four Galileo in-orbit validation satellites already in space. Launched in pairs in October 2011 and October 2012, these four satellites — the minimum required to obtain a position fix — served to demonstrate and validate the space and ground segments of the system.

Galileo SATs 7-8 are scheduled to follow end of year 2014. Then the constellation will be gradually deployed with six to eight satellites launched per year using a series of Soyuz and Ariane launches from Kourou, along with remaining elements of the ground network.

Satellite “Midwives”

Galileo’s post-launch team at ESA has finalized its preparations for taking control of the twin satellites. Following launch, the most crucial point in the flight comes when the two satellites separate from their upper stage — and the Launch and Early Operations, or LEOP, phase begins, run from ESA’s Space Operations Centre, ESOC, in Darmstadt, Germany.

If the moment of separation is the point when satellites are born, then the LEOP team can be thought of as midwives.

Any tumbling from the satellites being pushed away pyrotechnically must be corrected, and their positions stabilized in space. Next, they have to deploy their solar wings, to ensure a steady flow of power.

Flight Operations Director Hervé Côme at ESOC.

Then comes time to switch on and check out all the satellite systems one by one, to ensure everything has endured the launch in working order.

If all goes well, LEOP should take about a week before control of the satellites can be handed over to the Galileo Control Centre in Oberpfaffenhofen, overseeing the satellites, and ESA’s Redu centre in Belgium, for detailed payload testing.

Galileo’s LEOP team has been in training for months, explained Hervé Côme, flight director for Galileo at ESOC, with preparations stretching back two and a half years. “A simulation campaign has been running since March and the system and its operators have performed flawlessly,” Côme said. “To date, 20 simulations, in both nominal and contingency cases, have been conducted.”

Testing Teams and Technology

The satellites themselves participated in multiple end-to-end system compatibility tests to ensure that they are fully compatible with the various elements of the Galileo ground segment, extending to far-flung ground stations variously belonging both to ESA and to France’s CNES space agency, the Agency’s partner for LEOP.

A joint team from ESA and CNES oversaw LEOP for the first four Galileo satellites, similarly launched in pairs in 2011 and 2012. That work was carried out from CNES’s LEOP and Network Operations Control Centre in Toulouse, France.

This time, ESOC is hosting the LEOP team, with mission control and flight dynamics systems inherited from the first four in-orbit validation satellites adapted for these new Full Operational Capability (FOC) Galileo models.

The LEOP procedures and timeline have been fully validated, and system configurations frozen. From here on in, ESOC’s Mission Control Team — following a short summer break — will concentrate on further fine-tuning their organization and procedures in advance of next month’s launch.

The Galileo FOC satellite named “Milena” is mated on its Soyuz dispenser unit, joining the already-installed “Doresa” satellite.

The completed dispenser unit is ready to be transferred from the S5 payload preparation facility at the Spaceport in French Guiana for its integration atop Soyuz’ Fregat upper stage.