Euro space agency's Galileo satellites stricken by mystery clock failures Europe's GPS-alike system Galileo is suffering a number of unexplained clock failures on its satellites, the European Space Agency has admitted. Each of the 18 Galileo satellites currently in orbit carries four maser*-based atomic clocks. Two clocks are hydrogen-based, while the other pair use rubidium. The ESA says the clocks …
"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.
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.
[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.
"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!
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.
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.
"
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.
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.
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)
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.
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.
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.
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.
>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.
"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]
This post has been deleted by its author
Not quite. The staff of the OS were originally recruited to make maps for such purposes during WWI. But.
Between the wars, there was a fear that because the government had no legal reason to maintain the OS in peacetime the skill-base would be lost*, so they came up with a spiffing wheeze; a proposal to map the entire British Isles to a scale of one inch to one foot.
In the very late sixties they were nearly done, when the country decided it was going to go metric in a bid to make the French more receptive to EEC membership, and the OS were tasked with doing the job over to 1:50,000 scale.
The original OS 1 inch to one mile scale maps had bright red covers. In order that there should be no confusion (the overall coverage of any given map was slightly different in the newer scale) the newer 1:50,000 ones had bright pink covers.
For a glorious couple of years you could actually get both, though the red ones quickly disappeared once the series was complete. How do I know? Because I was there, and a keen Outward Bounder at the time.
You get a truly gobsmacking amount of information on one of these maps, enough that should one have a selection of landmarks including churches (ruined or otherwise, with a tower or spire or neither), power lines (the national and super grids were distinguishable), a railway line (especially if it ran over an embankment or through a cutting), a windmill (ruined or working) or a road (minor, major, A or B) or a raft of others (rivers, lakes, canals) a compass is actually superfluous. And all before you start examining the contour information to identify hills by their steepness.
I bought one for every single place I worked a contract and the route to it from Coventry. I can show you on the one of Land's End where to stand almost to the yard in order to see <i.why</i> they call it The Lizard. The one I have of Corris is from before the heritage railway was up and running, so the railway isn't shown - but the ancient trackbed is along with the reasons it was built in the first place.
More modern ones even include scenic lookouts for the traveler with a camera.
The American GS maps are nice, but not *as* nice. Different reason for making them, see?
Yes, I miss the OS map rack in W.H.Smiths.
* If anything illustrates a difference in attitude between then and now, this does.
Mmm not so much. Great detail, and perfect for reading on some sort of e-device but lacking the superduper features of an OS paper map. I'd say why but limit it just to the key and let people look it up for themselves.
That said, this is a great steer and thanks many times over, jake.
"Comes to that, why not just learn to read a flippin' map?"
Ah, pretty as they may be, they don't have a little arrow that says "you are here" do they ?
While you can (sort of) calculate your position from landmarks, sun or stars, that little arrow is much more accurate for most of use.
"If you need "that little arrow" to tell you where you are on a map, I respectfully suggest that your inability to understand how to read a map will make "the little arrow" fscking useless."
Different use case. Having a paper map and knowing how to use it will tell you where you are. You can then use it to find out where you want to be and then calculate how to get there. Great for hiking, or planning a driving/touring holiday trip. Using a SatNav, it's doesn't matter where you are. It's only use is to tell it where you want to be and then let it tell how to get there.
TL'DR
Paper maps - for when the journey is part of the fun.
SatNav - for when you just want to get somewhere without hassle.
"Paper maps - for when the journey is part of the fun.
"SatNav - for when you just want to get somewhere without hassle."
Or having the data in a paper map on your phone, and using it without the GPS system like I do. Coz my phone is a lot smaller and lighter than a street directory. Best of both worlds.
Large amounts of west Oz lack recognizable landmarks - even from aerial photos. This is before the landscape is rearranged for mining purposes which is the justification for going there in the first place, and changes the topography much faster than any publication schedule could keep up with.
I have enjoyed recreational map following holidays, but for convenience, productivity and accuracy in an industrial/mining environment,. GNSS is king
With an OS map there is no calculation required, just visibility out to the required landmarks and one working eye.
Never heard of anyone driving up a flight of steps and through an active worksite when working from a map either. Nor having a strident voice demanding in increasingly hysterical tones that I drive into Manhattan despite having set waypoints to prevent that very disastrous routing beforehand.
I might very well have had the same trouble with barricaded Washington DC roads not shown on a map either, but then I wouldn't have planned a route through DC in the first place.
"Comes to that, why not just learn to read a flippin' map?"
Because they are usually, at least a year or two out of date by the time they are printed. And none show actual addresses or postcodes, let alone the nearest pub!
On a slightly more practical note, in my case, I travel a lot so a years worth of paper maps would cost nearly as much as a cheap satnav, ie general Road Atlas + street maps of the various towns and cities + OS maps to find the smaller roads/villages that the road atlas "helpfully" ignores to make the maps "clearer"
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".
I think a recording of the media briefing is here:
http://www.esa.int/spaceinvideos/Videos/2017/01/DG_media_briefing
(I can't access it as it seems to want to run Flash, which the device I'm using right now doesn't support)
I also can't find anything on the ESA website referring to the problem - they might be a little embarrassed.
I also can't find anything on the ESA website referring to the problem - they might be a little embarrassed.
Coming hot on the heels of of Schiaperelli they aren't covering themselves in glory, I'd tend to agree. Luckily it is a pan-European project, so everybody can blame somebody else, although the Guardian will presumably (again) conclude that it is all because ESA doesn't have enough women running it, or the staff wear the wrong t-shirts.
"I can't access it as it seems to want to run Flash"
Their site must have been hacked, as it's trying to make me install a virus: "Get Adobe Flash Player"
On a more serious note, it's really sad that ESA still relies on Flash in this day and age!
You know what the fellow said – in Italy, for thirty years under the Borgias, they had warfare, terror, murder and bloodshed, but they produced Michelangelo, Leonardo da Vinci and the Renaissance. In Switzerland, they had brotherly love, they had five hundred years of democracy and peace – and what did that produce? The Swiss Cantonal Observatory of Neuchatel.
Exactly because they didn't use warfare, terror, murder and bloodshed to gather the money to pay for some wall art and statues. And some of them were also Popes who shouldn't have had any interest in earthly richness.... (Swiss has been supplying their guards for centuries, anyway).
It's fairly easy to forget that art was often paid by tears and blood of those not so lucky to be the ruling upper class. We're returning there anyway.
And BTW: I would exchange many Leonardo plus some Michelangelos and Raffaellos for a single Euler. Leonardo was essentially an early sci-fi author. Sure, anybody can understand Leonardo drawings. Understanding Euler mathematics is a not so easy.
Galileo was far more advanced, but because he didn't draw on walls - something even a Pope can understand - it became less famous.
Most of Leonardo knowledge was well behind Greek and Hellenistic one, achieved centuries before, and then mostly forgotten by hordes of ignorant - which understood precious items, but not precious knowledge.
Whoever built the Antikythera mechanism had engineering and mathematical knowledge far more advanced than his - and the machine was *built*, not just drawn.
Leonardo is like a pop star. Easy to "listen to". No much effort required. Do you ever read Galileo books? They are fantastic, he was a great writer too. Just, not many images to look at - not exactly children books...
"Whoever built the Antikythera mechanism had engineering and mathematical knowledge far more advanced than his - and the machine was *built*, not just drawn."
Even if all his work was independently (re-)discovering "lost" information the Greeks or whoever had many, many years earlier, then that's not his fault. It was lost and he deserves full credit for his discoveries.
On the other hand, if he had access to earlier books and just regurgitated them with a some new discoveries, then maybe there's a case for calling him a "pop star"
Though Cuckoo clocks are perhaps a Bavarian thing and not really Swiss?
They have all that nice cheese, dried beef, salami ...
Did Graeme Green (original book author) or Orson Welles write the monologue? Though it really suited the Harry Lime character, the people just being "dots", and thus to Harry it didn't matter that he was killing children with his diluted penicillin.
Hmm. It looks like Welles had to improvise a line for timing purposes, but he got the comparison from someone else (possible source: James Abbott McNeill Whistler).
Harry Lime didn't just get the thing about the cuckoo clocks wrong (they are from the Black Forest) - the Swiss had a couple of wars in ther time, the last being the civil war of 1847. Which, as far as wars go, was comparatively polite.
Correct.
Canada is a member of ESA, and Canada is notable for not even being in Europe, let alone the EU.
ESA is, in effect a buyers' club. Governments put money into a pot, and ESA divvies out the money in such a way as to ensure that the same amount goes back to each country, give or take. Of course, you can only buy what's made in a country, but there's a surprising amount of design and research done in aerospace even in countries with no actual aerospace industry.
Obligatory Brexit: The UK has no plans to leave ESA (it's actually one of the net beneficiaries of the fund, with UK firms being awarded more in contracts than the UK government puts into the pot)
Canada is a member of ESA, and Canada is notable for not even being in Europe, let alone the EU.
With Trump getting inaugurated tomorrow, perhaps Canada would like to be able to cast off, sail across the Atlantic and anchor somewhere off the French coast, perhaps form a land bridge between France and the UK.
Might have to turn it sideways to fit it in without also forming a land bridge to the eastern coast of the USA...
I'm surprised that a journalist on an erstwhile techie website thinks we need to have the MASER acronym explained to us!
MASERs aren't new, just a little bit older than LASERs.
Back in the day we spelled it M.A.S.E.R. and I think the New York Times and Washington Post still hold with that style.
"Maser: “microwave amplification by stimulated emission of radiation”. A device that emits microwave radiation in a very precise manner, similar to how a laser emits light."
<pedant>
Call me uber-picky, but the MASER came first by around 7 years, so LASERs need to be described in terms of MASERs.
</pedant>
While we're on the subject of population inversions, am I the only one to notice that the M40 on a Friday evening shows a classic inversion where the two inner lanes are almost empty and the rightmost lane is nose-to-tail traffic (albeit generally quite fast-moving), does anyone have any idea what it would take to turn the motorway into a CASER (Car Ammplification ...)?
Where's my coat?
Edit: The perils of posting without reading all the previous comments. Sorry @Jan 0.
Given the state of knowledge imparted by modern education I doubt that explaining the origin of "MASER" actually explained much. There are lots of folks that are aware of lasers as glorified flashlights (or electric torches in some geographic corners) that are really cool for things like pointing at charts in marketing sessions and letting you know where the scope thinks you are pointing the rifle.
"I thought microwaves were photons; doesn't that make the M.A.S.E.R/L.A.S.E.R argument a little redundant?"
Yes, as far as physics is concerned, "light" refers to the entire electromagnetic spectrum, so masers are just subsets of lasers. Plus, it's worth bearing in mind that we also have IR, UV and x-ray lasers, and they're always just called lasers. Maser get their own name partly because they came first before being generalised to lasers, but probably mainly because they're the only sub-variant that doesn't sound really stupid.
As for the article itself, there's surprisingly little information given here. The BBC article is much more informative - http://www.bbc.co.uk/news/science-environment-38664225
In summary - there are three different failure modes identified. The three failures in the rubidium clocks all appear to be due to a short circuit and may be related to a test performed before they are launched. The hydrogen clocks have two failure modes, the most common one apparently being an issue with the clocks not starting back up if they're turned off for too long (it's implied that although there are four clocks on each satellite, they're not all running continuously and that this can be worked around by simply changing how long they're turned off for). Only 2/14 of the main operational satellites have been affected (all 3 rubidium failures and 1 hydrogen failure), while the other 5 hydrogen failures have been split between 3/4 of the early test satellites. Finally, the Indian sat-nav system uses the same clocks, but has not had any similar failures.
And to correct the article, which somehow cited the BBC article while missing out most of the information and getting half the rest wrong, the BBC did not note that one satellite has suffered two clock failures, it says that four of them have suffered two clock failures. This can be easily seen by a little simple arithmetic on the numbers above. Perhaps next time just linking to the competent article and leaving at that would be a better idea?
A page from the ESA website dating back to 2001 identifies the original makers of the rubidium clocks as the Swiss Cantonal Observatory of Neuchatel, which appears to no longer be a functioning scientific institute. (Hmm, research institute makes critical atomic clocks and disappears)
There is no other way, since Humanity has lost the possibility of going up to fix the damn things ever since the Shuttle program was canned.
So top launching them until you find the solution - there's enough space trash up there already.
There is no other way, since Humanity has lost the possibility of going up to fix the damn things ever since the Shuttle program was canned.
According to wikipedia, the FOC galileo satellites are approximately $58M apiece, with further $55M (ariane 5) to $30M (soyuz) per satellite launch cost.
On the other hand, the average cost of a US space shuttle mission was in excess of $500M, so using space shuttle to service navigational satellites is a pretty insane idea economically.
Furthermore, I rather doubt that the space shuttle would have been able to reach these satellites in the first place. Galilleo satellites have orbits with the semi-major axis of nearly 30,000 km. The space shuttle was not designed to reach orbits beyond 1000 km. Even if you could boost the altitude (e.g. by severely limiting the payload), the required orbit passes smack through both van Allen belts, which will severly limit the length of time astronauts can survive in these orbits.
So, overall, space shuttle would have been entirely useless for these types of missions.
There is no other way, since Humanity has lost the possibility of going up to fix the damn things ever since the Shuttle program was canned.
Ignoring that ESA never had a shuttle in the first place, could the Shuttle ever reach geo-stationary orbit?
A big- mouthed American general stated, even before Galileo satellites were launched, that the USA would destroy the G-satellites if the operators didn't 'comply with American orders' to shut the system down; in times of conflict.
Could these clock failures be due to a Stuxnet-like piece of malware?
Eh? What, did they disappear or something?
It says back in 2003 they developed a clock with accuracy 10^-15 which is superior to their 2001 model which only had accuracy 10^-14.
BUT AT WHAT COST, seems its a bit more finicky as a consequence. After which point the whole group was disbanded in disgrace, wot?
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