Category Archives: Galileo Space Segment

Galileo Space Segment

Galileo clock anomalies under investigation


Galileo Rubidium Clock (RAFS)

As first reported last November, anomalies have been noted in the atomic clocks serving Europe’s Galileo satellites.

Anomalies have occurred on five out of 18 Galileo satellites in orbit, although all satellites continue to operate well and the provision of Galileo Initial Services has not been affected.

Highly accurate timing is core to satellite navigation. Each Galileo carries four atomic clocks to ensure strong, quadruple redundancy of the timing subsystem: two Rubidium Atomic Frequency Standard (RAFS) clocks and two Passive Hydrogen Maser (PHM) clocks. Read more…

Atomic clocks failures onboard Galileo satellites

SSTL_PHMAcross the 18 satellites now in orbit, nine clocks out of 72 have stopped operating. Three are traditional rubidium devices; six are the more precise hydrogen maser instruments that were designed to give Galileo superior performance to the American GPS network.

Galileo was declared up and running in December. However, it is still short of the number of satellites considered to represent a fully functioning constellation, and a decision must now be made about whether to suspend the launch of further spacecraft while the issue is investigated. Read more…

Galileos 13 and 14 transmitting navigation signals

Galileos 13 and 14 encapsulatedOn 01 December Galileo satellites 13 and 14 begun transmitting navigation signals as fully operational members of the constellation.

The pair were launched from Europe’s Spaceport in French Guiana on May 24 (

After launch and maneuvers to reach their final orbital altitude, their navigation and search-and-rescue payloads were methodically switched on and checked out. Their performance was assessed in relation to the rest of Galileo system. Read more…

[vid] Galileo satellites 15–18, from final preparations to liftoff

This timelapse video shows Galileo satellites 15–18, from final preparations to liftoff on a Ariane 5 launcher, flight VA233, from Europe’s Spaceport in French Guiana, on 17 November 2016, accelerating deployment of the new satellite navigation system. Galileo is the Europe’s own global satellite navigation system. The full system of 24 satellites plus spares is expected to be in place by 2020.


Launch of 4 new Galileo satellites

Liftoff of Ariane flight VA233An Ariane 5 rocket has launched four additional Galileo satellites, accelerating deployment of the new satellite navigation system.

The Ariane 5, operated by Arianespace, lifted off from Europe’s Spaceport in Kourou, French Guiana at 13:06 GMT (14:06 CET, 10:06 local time) carrying Galileo satellites 15–18. The first pair was released 3 hours 35 minutes and 44 seconds after liftoff, while the second separated 20 minutes later.

The Galileos are at their target altitude, after a flawless release from the new dispenser designed to handle four satellites. Read more…

[vid] Galileo System status

Next Thursday 17 November at 10.06 Kourou Time/14.06 CET an Ariane 5 will launch Galileo satellites for the first time. Equipped with a specially designed dispenser, the European launcher will deploy four satellites: Galileo Sat 15, 16, 17 and 18. This video explains the current status of the Galileo system.


Four new satellites to join Galileo constellation

VA 233. Quad satellites see spaceOn 17 November at 13:06 GMT (14:06 CET), a single Ariane 5 rocket is set to propel four Galileo satellites into orbit for the navigation constellation’s first-ever quadruple launch. Mission controllers are training intensively for the complex space delivery.

Ariane 5 will use a new payload dispenser to release four identical satellites into orbit in one go.

This will be the eighth Galileo launch, and will bring the number of satellites in space to 18. Once complete, the system will sport 24 operational satellites and a ground network to provide positioning, navigation and timing services. Read more…

Ariane 5 ready for first payload of Galileo satellites

ariane 5's bay hoisted for integrationThe initial Ariane 5 to loft four global positioning satellites for Europe’s Galileo navigation system has begun its build-up at the Spaceport in French Guiana for a milestone Arianespace mission in November.

This launcher is an Ariane 5 ES version that began the integration process begining of October, with the cryogenic core stage’s positioning over a mobile launch pad, followed by integration of the vehicle’s two solid propellant boosters.

Designated as Flight VA233 in Arianespace’s numbering system, the mission’s Ariane 5 was assembled inside the Spaceport’s Launcher Integration Building. During activity in the Spaceport’s Launcher Integration Building, the heavy-lift vehicle for Arianespace Flight VA233 underwent the assembly process that began by mating Ariane 5’s two solid propellant strap-on boosters with the main cryogenic stage. Read more…