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Euro space agency's Galileo satellites stricken by mystery clock failures

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Forgot?

Forgot to wind them up?

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Re: Forgot?

Maybe they didn't pack enough bird food for the cuckoo?

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Re: Forgot?

The hamster in the reaction wheel ate the cuckoo's food?

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Windows

Re: Forgot?

Downvote for saying the bleeding obvious.

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Re: Forgot?

Elements of the US establishment have gone rogue on the world, the US will not be defeated which means sabotaging other countries efforts.

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Re: Forgot?

Downvote for mentioning that the obvious was obvious.

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Windows

Re: Forgot?

yeah, realised my mistake. Typing one-handed and a Bluetooth keyboard from LIDL.

(I'd give my right arm to be ambidextrous)...

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Anonymous Coward

Re: Forgot?

Could a hamster-powered reaction wheel work in microgravity?

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Re: Forgot?

"Could a hamster-powered reaction wheel work in microgravity?"

Yes of course, you just strap the hamster in, which is the same way astronauts use the treadmill on ISS. Unfortunately the poor bugger won't be unable to unstrap himself for a bit of R&R after a hard day and couldn't be trusted to strap himself back in again independently either. So you'd need a hamster with a bit of longevity in it and preferably a backup hamster too.

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080

Re: Forgot?

Obviously you didn't

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Re: Forgot?

Hamasters in spaaaaaace......

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Pint

Re: Forgot?

Up voted for seeming to be honest and not try and convince us you were tech savvy and so using Siri/Contana/Google/Alexa/whatever on your 5G phone, whilst sitting in a driverless Tesla doing 112 (kmph)...

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Boffin

Re: Forgot?

In Spaaace no one can hear you chime.

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Anonymous Coward

Re: Forgot?

"the US will not be defeated which means sabotaging other countries efforts."

Can hear the conversation now,

"They're doing what? Well, we misy make sure we stay ahead, they're not going to trump us."

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Go

Re: Hamster-powered reaction wheel

Shirley, as there is micro-gravity, you just need a much heavier Hamster. PP

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It's not a GPS-alike it's a GPS!

Technically the US GPS system is called Navstar and was the first Global Positioning System, so Galileo is a Navstar-alike system but both are GPS, or at least will be when ESA have enough working satellites in place.

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Re: It's not a GPS-alike it's a GPS!

The usual acronym for a generic satellite positioning service is GNSS (global navigation satellite system). The one provided by the US Navstar satellites is called GPS. Yes, it is a Global Positioning System and the acronym would do perfectly well as a catch-all term, but is has become so strongly associated with the US Navstar system (like Hoover with Vacuum cleaners) that GPS on its own is usually taken to mean the US one.

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Headmaster

Re: It's not a GPS-alike it's a GPS!

[The term "GPS"] has become so strongly associated with the US Navstar system (like Hoover with Vacuum cleaners) that GPS on its own is usually taken to mean the US one.

No, actually, what you're saying is the exact opposite. You are arguing that the generic term "GPS" has come to be used to refer specifically to the US Navstar system, which would be like the generic term "vacuum cleaner" coming to be used to refer specifically to devices made by e.g. Hoover.

If people were starting to use the specific term "Navstar" when talking about just any GPS system then your analogy would be correct, but that's not what's happening.

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Re: It's not a GPS-alike it's a GPS!

I think you will find that Joe Public has never heard of GNSS, and whilst he probably thinks the US are the only providers, he doesn't actually care as long as his smartphone can tell him where the nearest pub is.

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Joke

Re: It's not a GPS-alike it's a GPS!

he doesn't actually care as long as his smartphone can tell him where the nearest pub is.

speak for yourself, I suggest for many younger users finding Pokemon is more important...

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Pint

Re: It's not a GPS-alike it's a GPS!

--- Sorry -- that post has been downvoted -- Reason -- not nearly silly enough ---

--- Try again when not sober ---

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Re: It's not a GPS-alike it's a GPS!

"I think you will find that Joe Public has never heard of GNSS, and whilst he probably thinks the US are the only providers, he doesn't actually care as long as his smartphone can tell him where the nearest pub is."

That same Joe Public probably doesn't have a smartphone. He has an IPhone. He may have bought it from Samsung or some other vendor, but it's still his iPhone, And GPS is that device he sticks on the dashboard to tell him where to drive (or an app on the phone) Either way, he probably doesn't ever think about how it works and may have heard the word "satellite" at some point in his life.

But thumbs up for using all available tech to find the pub!

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Re: It's not a GPS-alike it's a GPS!

I was gonna make a smart arse comment that I do not Hoover, except I checked and it turns out yes I do Hoover, dammit.

(usually the neat-o does most of the heavy lifting)

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Joke

Indeed, both are GPS, but only one of them has reliable clocks.... the other will put punters off by 100's of km if this is not fixed.

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Coat

... the other will put punters off by 100's of km if this is not fixed.

Which in turn might cause said punter to be late, as in "the late Dentarthurdent"

Sorry, couldn't resist. Mine is the one with the book on fjords in the pocket

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Actually this is a good point.

I think that a lot of systems might lock onto about what, 8? sources. But lets assume it only tracks perhaps 5.

How many of those 5 could be wrong, and how far off would the offset be?.

I am fairly sure data is regularly thrown out anyhow because it doesn't fit the standard of the other averages, it would still be interesting to know what type of issues it could cause.

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@Hans1

Did you RTFA?

Only one [clock] aboard each spacecraft needs to be operational for Galileo to function as designed.

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"

Indeed, both are GPS, but only one of them has reliable clocks.... the other will put punters off by 100's of km if this is not fixed.

"

Only if the clock does not keep accurate time. However in this case the issue is that the clocks are completely failing. If all clocks fail the punters will get no position at all. If some clocks remain working, the punters will get accurate positions. The nature of the clocks is such that they are likely to either be accurate or not work at all. Thus inaccurate position fixes (which is far worse than no fix at all) is not likely to occur.

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Depends on their definition of 'fail'

A clock that keeps inaccurate time is failed as far as its purpose goes, so it would probably be disabled and considered 'failed' at that point. That's easy to tell via 'majority rules' until you get down to two working clocks.

Even then perhaps there is some sort of signal being sent from the ground to the satellites which provides a time reference sufficiently accurate for it to tell when one of the two working clocks is no longer keeping accurate time and must be 'failed'.

I don't know the circumstances of these particular failures, and what mechanism would exist for an atomic clock to run slow or fast, but I have to think they've built in something to detect that and 'fail' any clocks that cease to maintain accurate time for obvious reasons.

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Re: @Hans1

I suspect that's incorrect and each needs at least three to be considered reliable enough to use.

With one the satellite has no idea in isolation if it's right or not, so it shouldn't offer its services for a fix. With three, if two agree and one does not it can be sure that the two are correct.

Hence four per sat, providing a redundant spare.

If I'm right, this is a real "brown trousers" problem for the ESA.

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Joke

@Hans 1

Ah, so, perhaps this is Apple's first attempt to counteract the internal map errors on iPhones...

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Joke

Missed title opportunity Ed.

Satellite clocks from Swish Swiss institute go all cuckoo on Galileo!

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Re: Missed title opportunity Ed.

Speaking of 3rd clocks (for avoiding indeterminacy when both of your clocks are telling different time) and assuming you're referencing the 3rd man:

http://www.imdb.com/title/tt0041959/faq#.2.1.4

TL;DR: no, the Swiss didn't invent cuckoo clocks

(Galileo, Galileo, Bee-el-zi-bug's got a daemon set aside for me)

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Anonymous Coward

It must be because Putin is personally hacking the satellite control systems - he likes the Beidou more, so he is trying to give it a leg up.

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Anonymous Coward

Guess Putin prefers Glonass...

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I don't know why, but every time I see the word Glonass I read it as Gonads... Must be my dickslexia...

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"Glonass"

The moon at night?

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I thought the US sat system clocks had to be constantly updated as they drifted from earth time. A few soldiers have a full time job tweaking the system daily. Were Galileo's clocks designed to be self sufficient, hence the 4 clocks of two types?

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I think it's the case that the clocks work OK, but it's the orbits of the satellites carrying that needs ongoing tweakage

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Galileo's clocks were probably designed to be redundant. A small number of failures were expected. So if one fails you have a backup. Even if there's a design or manufacturing flaw affecting all the clocks of one type then you still have 2 clocks of the other type.

This is because the cost of launching a satellite is so high, and it takes so long, so it's cheaper and better to have redundant systems in place.

However, if clocks of *both* types are failing at a much higher rate than expected, that's a serious problem.

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The US GPS system also carries 4 clocks per satelite, it's for redundancy and self-checking.

All the various systems are re-synced regularly - normally once a day as they pass over their owner's main ground station.

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"but it's the orbits of the satellites carrying that needs ongoing tweakage"

Sort of.

Each GPS satellite downloads an "almanac" of data that accelerates the process of finding other satellites. These include the orbital elements of those satellite. These drift slightly over quite a short period of time. That is why they have to be updated.

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Re: "but it's the orbits of the satellites carrying that needs ongoing tweakage"

Sort of.

Each GPS satellite downloads an "almanac" of data that accelerates the process of finding other satellites. These include the orbital elements of those satellite. These drift slightly over quite a short period of time. That is why they have to be updated.

Being pedantic: the satellite broadcasts the almanac. It's the GPS receivers that download it.

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Why not just leave the satellites on the ground, where you can go and fix them in a van...

... like eLoRaN?

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Anonymous Coward

Re: Why not just leave the satellites on the ground, where you can go and fix them in a van...

Getting a line-of-sight to your van may be a bit problematic for most applications not involving a Predator drone.

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Re: Why not just leave the satellites on the ground, where you can go and fix them in a van...

Comes to that, why not just learn to read a flippin' map?

The UK's OS maps are (or were, in '84 when I last bought one) elegant and eminently fit-for-purpose. Wish we had the same kind of maps in the USA.

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Re: Why not just leave the satellites on the ground, where you can go and fix them in a van...

Actually, they did this: in the test phase, the Galileo system consisted of just a few ground-based stations (placed somewhere in Bavaria IIRC.)

Google for "GALILEO Test and Development Environment".

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Re: Why not just leave the satellites on the ground, where you can go and fix them in a van...

>The UK's OS maps are (or were, in '84 when I last bought one) elegant and eminently fit-for-purpose. Wish we had the same kind of maps in the USA.

Well it's your own fault, if you insist on having a tantrum and storming out then you don't get to have nice things.

If you wish to invite the Ordnance Survey to tramp over your land armed with theodolites, marmite sandwiches and maps in little plastic cases around their necks then I'm sure they will be happy to do so.

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Re: Why not just leave the satellites on the ground, where you can go and fix them in a van...

"Well it's your own fault, if you insist on having a tantrum and storming out then you don't get to have nice things."

Eh? I'm an ex-pat but I didn't "storm off" anywhere.

[VOICEMODE=DALEK_RING_MODULATOR] Explain! Explain! [/VOICEMODE]

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Re: Explain! Explain!

Something to do with taxes and teabags I think.

About maps though, the UK Ordnance Survey are indeed very nice and practical but the Swiss maps are works of art and, fortunately, much more reliable than their space-going clocks.

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