10 atomic clocks aboard Galileo navigation satellites have failed and the ESA doesn’t know why

At least 10 atomic clocks onboard the European Space Agency’s (ESA) Galileo navigation satellite constellation have failed. India uses the same model of atomic clocks for its own satellite navigation systems.

The Galileo constellation of satellites is meant to be an alternative to the existing GPS (US), Glonass (Russia) and Bei Dou (China) global positioning systems. It’s designed to give the European Union its own positioning system.

Called the Global Navigation Satellite System (GNSS), it’s an advanced version of current GPS implementations and offers higher precision positioning and latitude information to customers. Lower resolution data will be available for free to consumers and the like.

A special feature of GNSS is an in-built Search and Rescue (SAR) functionality that not only relays SOS information, it also informs the emergency beacon of the status of the request.

Key to the operation of these satellites is its atomic clock. These clocks provide incredibly accurate timing information that is essential for accurately measuring positional data.

26 satellites are needed for a fully operational GNSS and 18 of these satellites are already in orbit. Four more satellites are to be launched by the end of the year.

The satellites use older rubidium atomic frequency clocks and newer, more precise hydrogen maser clocks. Three of the former and seven of the latter clocks have failed in the last two years. One hydrogen maser clock has restarted, however, reports Space News.

Thankfully, each satellite is equipped with three of each kind of clock, which allows for a great deal of redundancy. As such, all the satellites are still operational and the plan to launch the remaining 8 satellites will remain on schedule.

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The ESA does state that a plan to refurbish the existing clocks is in the works. It also believes that short-circuits caused the rubidium clocks to fail and that the others may have failed because they were switched off for long periods.

While the ESA is still investigating the cause of the problem, given the inherent redundancy in the system, it intends to maintain the launch schedule.

China and India reportedly use the same atomic clocks for their satellite navigation systems and the ESA claims to have “contacted India about the problems.”