'Failed' clocks fresh blow for Europe's Galileo satnav (Update)

Galileo satellite
Artist's impression of a Galileo satellite. Credit: ESA.
Europe's beleaguered Galileo satnav has suffered another setback, with clocks failing onboard a number of satellites in space, the European Space Agency said Wednesday.

Designed to render Europe independent from America's GPS, the 10 billion-euro ($11 billion) project may experience further delays as the cause of the failure is investigated, ESA director general Jan Woerner told journalists in Paris.

Eighteen orbiters have been launched for the Galileo constellation to date, a number that will ultimately be boosted to 30 operational satellites and two spares.

Early, initial services were launched in December, and the failure of nine clocks out of 72 launched to date has not affected operation, Woerner said.

No satellite has been declared "out" as a result of the glitch.

"However, we are not blind... If this failure has some systematic reason we have to be careful" not to place more flawed clocks in space, he said.

Each Galileo satellite has four ultra-accurate atomic timekeepers—two that use rubidium and two hydrogen maser.

Three rubidium and six hydrogen maser clocks are not working, with one satellite sporting two failed timekeepers.

Each orbiter needs just one working clock for the satnav to work—the rest are spares.

The question now, Woerner said, is "should we postpone the next launch until we find the root cause?"

The next four satellites were to have been hoisted into space in the second half of 2017.

"You can say we wait until we find the solution, but that means if more clocks are failing then we are reducing the capability of Galileo," the director general said.

"If we launch we will at least sustain if not increase the possibility of Galileo, but we may take the risk (of) a systematic problem."

It was also not known whether the broken clocks can be fixed.

Taking risks

ESA boasts that Galileo has the most accurate atomic clocks ever flown for geolocalisation.

Similar to traditional clocks relying on the tick of a pendulum, atomic timekeepers also count regular oscillations, in this case switches between energy states of atoms stimulated by heat or light.

The project has already experienced many setbacks, taking 17 years and more than triple the original budget before going live last month.

In August 2014, after a more than year-long delay over "technical difficulties", satellites number five and six were placed into a lopsided, elliptical orbit—delaying subsequent launches.

The civilian-controlled service is seen as strategically important for Europe, which relies on two military-run rivals—GPS and Russia's GLONASS.

Neither provides a guarantee of uninterrupted service.

Woerner defended the decision to create an autonomous European satnav system based on European technology.

"If you want to be competitive in the global market you should not rely in too many aspects on the technology of others," he said.

"If you only use proven technology, you have no further development... We ought to take risks in order to learn, in order to be competitive in the future."

Last October, ESA's Mars lander Schiaparelli, designed to test technology for a future rover, crashed into the Red Planet.

It had been Europe's second failed attempt to reach the Martian surface.


Explore further

Galileo: Europe's rival to GPS

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Jan 18, 2017
12% clock failure is good by ESA standards.
But hopefully the clocks have just hit their control-loop-end-stop alarms, and just need a coarse control trim and a reset. I had to trim rubidium clocks occasionally to keep the control voltage from drifting off centre as the tubes aged.

Jan 18, 2017
The rubidium clocks aren't the main ones. The hydrogen maser ones are the primary clocks (roughly 10 times more accurate than rubidium clocks). A bit worrysome that most of the failures are from the hydrogen clocks.

Jan 18, 2017
The failure rate is troubling.
This might not have a random cause since there are several nations who might not favor a Galileo success.


Jan 18, 2017
This might not have a random cause since there are several nations who might not favor a Galileo success.


There is no point in speculating about conspiracy while ignorance and incompetence have not been eliminated as primary causes. Launching and maintaining spacecraft functionality is hard. Even the most subtle oversights can have huge ramifications.

Jan 18, 2017
Neither provides a guarantee of uninterrupted service.


Neither does Galileo. It was supposed to operate on the same/adjacent frequency bands as GPS, but US demanded they shift, so they can jam the Galileo frequencies at will without disrupting their own.

Reason being that the GPS system is designed in two parts to block civilan use while maintaining military access, whereas Galileo is open to all by design, so the US wants a means to shut down Galileo to deny its enemies access to satellite navigation. During the negotiations, the US military threatened to shoot down the satellites in time of conflict should the EU refuse to use a different frequency.

So that really makes Galileo just "GPS me-too".

Jan 18, 2017
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Jan 18, 2017
The further trouble is that Galileo is dependent on GPS to provide full 24/7 coverage until the full constellation of satellites is up and running. That's because the satellites are not geostationary - they're not visible in the sky around the clock.

In the mean while, GPS is being upgraded to equal or better accuracy than Galileo, so the long delays and setbacks mean that when Galileo becomes "independent" of GPS, it's already obsolete.

So what's the point?

Well:
https://en.wikipe...igation)
In January 2011 infrastructure costs up to 2020 were estimated at €5.3 billion. In that same month, Wikileaks revealed that Berry Smutny, the CEO of the German satellite company OHB-System, said that Galileo "is a stupid idea that primarily serves French interests".


Basically, it's a boondoggle to bring money and continued launch contracts to the French aerospace industry.

Jan 18, 2017
There is a geomagnetic storm happening right now.
Maybe this has something to do with it?

Jan 18, 2017
Why don't the Europeans replace the inherently expensive and technologically fickle Galileo satellite constellation with the more reliable and cheaper ground based GPS system from Locata.

At least in mainland Europe that is a readily achievable solution.

Global GPS will still use satellites for the time being.

Jan 19, 2017
So we have Russia who does not want Europe to succeed and has a history of heavy hacking attacks in Europe. We have China who does not want Europe to succeed and has a history of massive hacking in Europe. The US which does not want Europe to succeed much and has a history of massive hacking in Europe. It is certainly not sure whether they hacked it and installed corrupt software but i would certainly take all options into account. Especially since Galileo is expected to greatly surpass the Russians and Chinese systems in precision and even go way beyond GPS in precision and new capabilities. This will likely make Galileo the main used system over the coming decade in chips in phones and cars. Though they will likely use a combination of all available systems it would put Europe ahead of the game just like it happened with CERN vs the US Fermilab. Just as it happened with ESO now operating the worlds largest telescopes. Just like the AIRBUS rise. And many new upcoming EU developments.

Jan 19, 2017
with the more reliable and cheaper ground based GPS system from Locata.

Locata works in open areas. GPS/Galileo/GLONASS is better for urban areas. Europe is highly urbanized.

The aim of Galileo is to bring precision into the range where it can be used (reliably) for vehicle guidance.

As for the conspiracy theorists: yeah. You'll always have conspiracies. Let's first let these guys do their analysis before knee-jerking, OK?

Jan 19, 2017
The failure rate is troubling.
This might not have a random cause since there are several nations who might not favor a Galileo success.


Like the ones that pay for populist parties in our countries? Hmmm....

Jan 19, 2017
The aim of Galileo is to bring precision into the range where it can be used (reliably) for vehicle guidance.


Or so they wish.

None of the above, GPS, Galileo, GLONASS are particularily good in built-up urban areas because there's plenty of multi-path echoes, and buildings and overpasses, bridges etc. blocking direct sight to the satellites, so the recievers get a load of random errors trying to measure the time of flight of the signal and they have to average their location over a long time constant measured in seconds or even minutes.

Getting the accuracy down to where it could drive an unmanned vehicle down a city street is a nice pipedream. The actual fix with GPS right now wanders about randomly in a 40-50 meter radius. Getting it down to 1 meters would be an absolutely phenomenal achievement, yet it still wouldn't be accurate enough for a car: 1 meter off and you're driving on the sidewalk.

Jan 19, 2017
The actual fix with GPS right now wanders about randomly in a 40-50 meter radius. Getting it down to 1 meters would be an absolutely phenomenal achievement, yet it still wouldn't be accurate enough for a car: 1 meter off and you're driving on the sidewalk.

You must be using some shitty equipment or simply don't know what you are talking about.

Jan 19, 2017
The actual fix with GPS right now wanders about randomly in a 40-50 meter radius. Getting it down to 1 meters would be an absolutely phenomenal achievement, yet it still wouldn't be accurate enough for a car: 1 meter off and you're driving on the sidewalk.

You must be using some shitty equipment or simply don't know what you are talking about.

You must be using some of that shitty stuff between your ears or simply don't know how to read. He is referring to city driving, where buildings reflect the GPS signal resulting in inaccuracy.

Jan 27, 2017
You must be using some shitty equipment or simply don't know what you are talking about.


The GPS satellite clocks themselves and orbital inaccuracy causes errors up to 4 meters.

Variations in the ionosphere add up to 5-7 meters.
Reciever noise contributes to about 1 meters of error and multipath echoes (ground reflections) in an open field cause another 1 meters of error.

All told, with an average good reciever on an open field you'd expect the individual point measurements to have a random walk over a 10 meter radius. The system takes several measurements a second and averages them to gain a more accurate position.

If you're shadowed by one side by a tall concrete building full of rebar and an open field to the other side, the measurement can wander hundreds of meters because the signals from the building side take an extra trip to reflect around. In these cases, car satnavs simply guess where you are based on your previous location history.

Jan 27, 2017
The reason why GPS is sensitive to multipath and ionosphere variation is because the system operates by measuring the relative time of flight between satellites.

The satellites are broadcasting a continuous signal that says "The time is now... the time is now... the time is now..." - so that when you hear two satellites that appear to report the exact same time, you know you are standing exactly equidistant to those satellites. Hearing different times lets you calculate the relative distance to both satellites.

When one or more of the satellite signals takes a detour and bounces off a near building, it adds that distance to the time of flight and alters the apparent ratio between the two. Similiarily, when the signal goes through the ionosphere it bends and takes an indirect route.

So when surveyors want a precise GPS fix, they leave the device on for hours to average out the errors. A car satnav needs an update every 2 seconds, so it gets lousy accuracy.

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