Galileo Working, but Some Clocks Failing

January 20, 2017

Editor’s Note: Each satellite has four clocks aboard, so these failures have not been fatal for the system, nor even an individual satellite. They are worrying, though, as you will read below.

 

Galileo satellites experiencing multiple clock failures

The onboard atomic clocks that drive the satellite-navigation signals on Europe’s Galileo network have been failing at an alarming rate.

Across the 18 satellites now in orbit, nine clocks 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.

Prof Jan Woerner, the director general of the European Space Agency (Esa), told a meeting with reporters: “Everybody is raising this question: should we postpone the next launch until we find the root cause, or should we launch?

“You can give both answers at the same time. You can say we wait until we find the solution but that means if more clocks fail we will reduce the capability of Galileo. But if we launch we will at least maintain if not increase the [capability], but we may then take the risk that a systematic problem is not considered. We are right now in this discussion about what to do.”

Still operational

Each Galileo satellite carries two rubidium and two hydrogen maser clocks. The multiple installation enables a satellite to keep working after an initial failure.

All 18 spacecraft currently in space continue to operate, but one of them is now down to just two clocks.

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