Galileo satellites experiencing multiple clock failures(bbc.com)
bbc.com
Galileo satellites experiencing multiple clock failures
http://www.bbc.com/news/science-environment-38664225
188 comments
Not good enough to run a data center is still stable enough to help bounce signals off the moon.
Out of curiosity, why does a data center need a Rb clock?
Out of curiosity, why does a data center need a Rb clock?
Very accurate time is important for some applications: https://www.wired.com/2012/09/google-spanner/
Not at this level. The Rb resonance in question is ~6.8 GHz, which means that counting it (which is functionally all atomic clock is really doing) will give you accuracy higher by definition than the cycle time of the CPU running your timing-sensitive application.
GPS needs that because at the speed of light in vacuum that corresponds to ~2cm of wavelength, which is only 2 orders of magnitude from the design accuracy of the whole system.
GPS needs that because at the speed of light in vacuum that corresponds to ~2cm of wavelength, which is only 2 orders of magnitude from the design accuracy of the whole system.
Cycle-to-cycle accuracy of an atomic clock (then called a timing and frequency standard) is never dominated by the resonance frequency, and you never extract the timing information from the radio-frequency that interacts with the physics directly.
The reference frequency used externally for timing is the reference oscillator which typically was 5 or 10 MHz, but nowadays tends to be 100 MHz as HF electronics became better.
For an older Caesium clock, a block diagram is explained on this page: http://www.leapsecond.com/museum/hp5062c/theory.htm
{a Rb clock is very similar electronically, only you are not looking at count-rates of Cs atoms flying through your spin filter but you are observing the optical attenuation of a rubidium gas, both vary with radio-frequency waves being injected into the package. Also Cs is a primary standard and Rb is very stable - but adjustable and susceptible to extarnal magnetic fields.}
From the reference frequency, a series of synthesizers / multipliers generate the radio frequency that is relevant to the physics process. And this frequency is then modulated slightly (137 Hz label in Figure 5) so that correlation in the physics process from being too high, or too low in resonance frequency, can be observed (Figure 9, you vary between f2 and f1 137 times per second).
A good GPS steered quartz oscillator will use around 100s of loop time-constant, the time constant for the control loop in a caesium clock will be much higher.
The reference frequency used externally for timing is the reference oscillator which typically was 5 or 10 MHz, but nowadays tends to be 100 MHz as HF electronics became better.
For an older Caesium clock, a block diagram is explained on this page: http://www.leapsecond.com/museum/hp5062c/theory.htm
{a Rb clock is very similar electronically, only you are not looking at count-rates of Cs atoms flying through your spin filter but you are observing the optical attenuation of a rubidium gas, both vary with radio-frequency waves being injected into the package. Also Cs is a primary standard and Rb is very stable - but adjustable and susceptible to extarnal magnetic fields.}
From the reference frequency, a series of synthesizers / multipliers generate the radio frequency that is relevant to the physics process. And this frequency is then modulated slightly (137 Hz label in Figure 5) so that correlation in the physics process from being too high, or too low in resonance frequency, can be observed (Figure 9, you vary between f2 and f1 137 times per second).
A good GPS steered quartz oscillator will use around 100s of loop time-constant, the time constant for the control loop in a caesium clock will be much higher.
I'm not following your ire. I don't understand why you think adding all the detail above is inconsistent with "functionally, all an atomic clock is really doing is counting cycles (and, OK, tracking phase) of a known transition of some isotope or another. You're just describing how.
> before deciding the Russians hacked them
Actually, the first suspect is the US: https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
Actually, the first suspect is the US: https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
The frequencies have changed after everyone realized it was a pretty darn dumb proposal to begin with.
Also I like how everything is now being blamed on hacking, a freaking atomic clock that was launched on top of rocket into space fails and it's Russian hackers.
Also I like how everything is now being blamed on hacking, a freaking atomic clock that was launched on top of rocket into space fails and it's Russian hackers.
"Also I like how everything is now being blamed on hacking, a freaking atomic clock that was launched on top of rocket into space fails and it's Russian hackers."
The only mention I see anywhere of blaming hackers (Russian or otherwise) is VLM 3 comments up from you. It's certainly not in the linked article. Am I missing something?
The only mention I see anywhere of blaming hackers (Russian or otherwise) is VLM 3 comments up from you. It's certainly not in the linked article. Am I missing something?
I'm sure that actual Russian hackers would like to be perceived as people who can hack an atomic clock in space with no connection to earth :-) Such a feat would demonstrate some fairly elite skills would it not?
> and it's Russian hackers.
Seems to be the goto scapegoat for catastrophic failures, technical or otherwise.
Seems to be the goto scapegoat for catastrophic failures, technical or otherwise.
Russian hackers made my coffee pot overflow this morning.
When someone comes up with some conspiracy theory or someone suspecting my code to do something really weird I always try to imagine what it would take to actually pull it off. Let's say hackers really did this, how could you do the same if you really wanted to? Often it turns out you simply couldn't do it even if you wanted to.
> Esa is also in contact with the Indian space agency which is using the same clocks in its sat-nav system. So far, the Indians have not experienced the same failures.
Since the same technology and the same manufacturer is being used, it's a weird problem to have after the satellites are already in space.
Since the same technology and the same manufacturer is being used, it's a weird problem to have after the satellites are already in space.
My SWAG is that it's not a clock problem, it's a power supply problem.
All the satellites probably use the same clock power supply, regardless of which clock they chose to put into the satellite.
That would explain why you have the Indian clocks by the same manufacturer all working, and why two completely different clock technologies (hydrogen maser and rubidium) are both failing.
All the satellites probably use the same clock power supply, regardless of which clock they chose to put into the satellite.
That would explain why you have the Indian clocks by the same manufacturer all working, and why two completely different clock technologies (hydrogen maser and rubidium) are both failing.
It's not Indian clocks it's Switzerland clock, the compagny is spectratime in the town of Neuchâtel.
If they double everything they won't make this bad idea of sharing the same power supply.
If they double everything they won't make this bad idea of sharing the same power supply.
They're all the same clocks but the ones owned by India are working fine, so Indian clocks is a good description.
Would it be paranoid to contemplate sabotage?
After all, a global system has clear military value. In contrast the Indian system is limited in coverage to India and nearby nations.
After all, a global system has clear military value. In contrast the Indian system is limited in coverage to India and nearby nations.
Doesn't make any sense to me. If you wanted to avoid the threat from such a system, then you'd develop the techniques to sabotage it and then not actually do it until you needed it. If you sabotaged it now, then you'd just give them a heads-up that the system was vulnerable, and give them time to fix it.
Unless it was considered worth the effort to try and see if they could just jeopardize the system financially. For example, nation states have the capability to compromize industrial operations with specific viruses. If a uranium enrichment centrifuge can be targeted I don't think any system can be guaranteed to be infection free.
What makes you think they do not need it now?
The lack of any mention of a major military conflict on nytimes.com, cnn.com, and news.google.com is a pretty good indication. You don't need to care about a half-finished GNSS system if you're just bombing ISIS.
Unless you wanna kill it before it is deployed. For example if the U.S. was aware that a nation state was about to pull out on funding for it and wanted to keep the economic dominance of GPS.
Ukraine?
They'd jam GLONASS and block GPS in the area as well, if that were the case.
Ukraine is a major military conflict? Mexican drug related violence kills more per month than what is going in Ukraine for the past 3 years.
Mexican drug wars are violent but do not involve competing state militaries, so I would not call it a major military conflict. It's a criminal problem being solved using the military.
There are no competing state militaries, whilst Russia is involved it's military isn't there in any major capacity.
As far as the fighting goes the Ukraine is negligible considering all the armed conflicts around the world.
As far as the fighting goes the Ukraine is negligible considering all the armed conflicts around the world.
In the same vein, alcohol kills more per month than drug gangs. Doesn't make either of those a war, regardless of rhetoric.
Sat January 14, 2017
Poland welcomes thousands of US troops in NATO show of force
http://www.cnn.com/2017/01/14/europe/poland-us-troops-nato-w...
Poland welcomes thousands of US troops in NATO show of force
http://www.cnn.com/2017/01/14/europe/poland-us-troops-nato-w...
Are you proposing that the US would hack Galileo as part of stationing a few thousand soldiers on an ally's territory?
C'mon man keep up; all hacking now is the Russians. Just like a few years ago it was all the Chinese.
Good point. "now" being of course in the next 5 years.
While there is some possibility (a few percent chance?), in these cases I think the majority chance is Hanlon's Razor.
It's probably just a mistake on the ESA's part -- space is hard.
It's probably just a mistake on the ESA's part -- space is hard.
Agreed, as a software developer I often see confounding multiple problems. Sometimes they are related to a third origin, sometimes they are just two separate problems that happened at the same time by chance. Usually they appear when all the low hanging fruit (easy bugs) are gone. Software is not hardware, I know, but my guess is these satellites are buggy as hell.
https://youtu.be/HTVgPw7TR_k?t=31m13s [30c3]
"NSA/NRO sattelite parked next to major Middle-Eastern telecommunications sattelite"
"NSA/NRO sattelite parked next to major Middle-Eastern telecommunications sattelite"
Yes they are listening in, this isn't new the US and Russia have been launching SIGINT satellites since the late 60's....
Not a conspiracy-lover, but this is what came to my mind instantly considering there is a still-ongoing investigation about another ESA project - the failure of ESA's Schiaparelli landing, which slammed into Mars back in October 2016.
Every country but the US has had very bad luck with Mars landings. Its a non-trivial problem to solve and even the US's expertise and funding leads to failure sometimes.
https://en.wikipedia.org/wiki/List_of_missions_to_Mars
The idea that there's a conspiracy at work is ridiculous. We're not exactly at the "Star Trek" stage of humanity here. Landing on Mars is still risky.
https://en.wikipedia.org/wiki/List_of_missions_to_Mars
The idea that there's a conspiracy at work is ridiculous. We're not exactly at the "Star Trek" stage of humanity here. Landing on Mars is still risky.
I agree it's very unlikely that sabotage is what's going on, but what you're saying is the one compelling argument in favor of sabotage. "Everyone but that one actor has very bad luck" is exactly what sabotage looks like.
Except that actor has the most advanced space program in history. Its like saying Michael Phelps is part of a conspiracy to keep other swimmers from winning. Uh no. The world isn't one on even playing field. Some people are better than others and thus get better results.
Time to spin it the other way: the only reason the US landings on Mars are successful is because of secret government technology developed out of a covertly funded program from the 1950s as part of antigravity research.
Please remember that the Schiaparelli lander was an experimental lander. The intention was to test the landing technology. So yes, it failed to land, but it was not exactly unexpected...
It wouldn't be paranoid
However by reading the description provided it do seems more likely it's due to mistakes
Because things do behave differently "on production" and tests (and launches and space) do sometimes makes things worse
However by reading the description provided it do seems more likely it's due to mistakes
Because things do behave differently "on production" and tests (and launches and space) do sometimes makes things worse
Well, considering the energy put in by US and Russia to divide European union, I will not be surprised... Divide and rule, isn't it?
yes it's paranoid. nobody sabotages all of humanity's major triumphs this way, it's just not done and with good reason.
I say this as someone who likely subscribes to at least 20x as many conspiracy theories (defined as the existence of one or more people conspiring) as you do.
I say this as someone who likely subscribes to at least 20x as many conspiracy theories (defined as the existence of one or more people conspiring) as you do.
> nobody sabotages all of humanity's major triumphs this way
It may be "humanity's triumph" for you and me, but there are people who couldn't care less about that - people, for whom the only relevant thing is its impact on their political and economical standing. Such people are the ones who tend to find their way to positions of power.
It may be "humanity's triumph" for you and me, but there are people who couldn't care less about that - people, for whom the only relevant thing is its impact on their political and economical standing. Such people are the ones who tend to find their way to positions of power.
I said ”this way”. To me it is paranoid, yes. In my opinion nobody does this. (Don’t give them any ideas, either.) These are multiply redundant time sources aboard satellites in a multibillion euro program. Nobody is sabotaging them (in my judgment†), and we don't need to even bring the idea of this into the discussion. I won't reply to any more replies about this.
† Again as a disclaimer: I don't have a horse in this race and I subscribe to a ton of conspiracy theories (way more than you). This is just not one of them.
† Again as a disclaimer: I don't have a horse in this race and I subscribe to a ton of conspiracy theories (way more than you). This is just not one of them.
GPS is a military project controlled by the US. With just a switch of a button the civilian receivers will be practical worthless for navigation. They can't do that on Galileo or GLONASS. I imagine Russia can dial down GLONASS precision for civil use cases, too.
At least Galileo is a competitor, and the political/military discourse about it is still ongoing.
https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
At least Galileo is a competitor, and the political/military discourse about it is still ongoing.
https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
No, I believe your reasoning is sound.
Given the level of political sabotage it saw when already at drawing stages I would not be surprised.
You don't think it's a pretty big leap from political pressure (aka what all countries do to each other all the time) to sabotage, a literal act of war and something that would, if discovered, at the very least put Nato into serious jeopardy?
The sabotage doesn't have to be James Bond shooting a PPK into a wiring harness or dumping a test tube of mystery onto clock circuit boards.
The Americans spent a decade and a lot of money on the first gen system in the 80s (we're on like the forth or fifth gen of GPS sats now) and the sabotage could be as simple as making it a classified state secret that mounting the physics package such that the electrodes are vertical causes microfractures in the physics package due to launch vehicle pogo resulting in 6 month lifetime on orbit, max. Or maybe mounting the physics package horizontally. Or it was spin stabilization that killed it or ...
Or you thought kapton would be a great plastic film for high voltage high temperature insulation for the physics package but (mumble mumble secret squirrel stuff here) as documented in classified air force memo #classified, insert finger wagging here oh no you can't get more than 6 months lifetime on orbit shouldda used teflon (or vice versa)
It could be as simple as a pdf that should have been posted to arxiv.org about some engineering peculiarity of Rb cells getting classified and buried. Maybe because it cost the US government a billion bucks to learn it the hard way back in the 80s.
The Americans spent a decade and a lot of money on the first gen system in the 80s (we're on like the forth or fifth gen of GPS sats now) and the sabotage could be as simple as making it a classified state secret that mounting the physics package such that the electrodes are vertical causes microfractures in the physics package due to launch vehicle pogo resulting in 6 month lifetime on orbit, max. Or maybe mounting the physics package horizontally. Or it was spin stabilization that killed it or ...
Or you thought kapton would be a great plastic film for high voltage high temperature insulation for the physics package but (mumble mumble secret squirrel stuff here) as documented in classified air force memo #classified, insert finger wagging here oh no you can't get more than 6 months lifetime on orbit shouldda used teflon (or vice versa)
It could be as simple as a pdf that should have been posted to arxiv.org about some engineering peculiarity of Rb cells getting classified and buried. Maybe because it cost the US government a billion bucks to learn it the hard way back in the 80s.
Those things aren't impossible, but also I don't see how any of those things class as "sabotage". Facebook didn't sabotage Google+ by not revealing to them how to make a successful Facebook.
[deleted]
It wouldn't have to be the US. It could also be Russia or China (perhaps less likely).
Nah. Especially not after Stuxnet.
But that was targeted at Iran, this would be targeted at the majority of Nato.
Edited to add: also, the fact that Stuxnet was discovered would be good reason to think you wouldn't attempt this. You'd need to be bullet proof certain that it would never be discovered.
Edited to add: also, the fact that Stuxnet was discovered would be good reason to think you wouldn't attempt this. You'd need to be bullet proof certain that it would never be discovered.
my thoughts too, Stuxnet but for GPS satellites. Too much of a threat to the US GPS system? Maybe a target for Russia but unlikely because they have no competing system. The only thing that leads away from it being US orchestrated is that they found Stuxnet, so if they found this you could be pretty sure that US/EU relations would be very shaky. Of course perhaps then Russia make it look like a US attack to divide a wedge between allies.
>> Russia ... have no competing system
Russia has GLONASS, China has BeiDOU, India IRNSS, Japan QZ
Russia has GLONASS, China has BeiDOU, India IRNSS, Japan QZ
apologies, I thought GLONASS was military use, I then checked and got stuck in wikipedia, meaning to come back and edit my comment, too late now though.
If you have a recent smartphone, you might be a GLONASS user and not even know it!
If it's an Android smartphone, recent versions of MobiWIA - Eclipsim's GPS Status & Toolbox app divide the satellite signal bar display into four sections (GPS, GLONASS, Beidou, and Galileo). Since my phone only supports GPS and GLONASS, the latter two don't show any bars.
> Russia but unlikely because they have no competing system.
Russian GLONASS had full constellation in 1995, then during late 90s it had breakages, but was fully restored by 2011 again.
EU Galileo has full constellation planed for 2020.
Russian GLONASS had full constellation in 1995, then during late 90s it had breakages, but was fully restored by 2011 again.
EU Galileo has full constellation planed for 2020.
GLONASS's information and analysis centre is awesome.
https://www.glonass-iac.ru/en/
https://www.glonass-iac.ru/en/
I wonder what design on the Soviet WWW would have looked like.
How is it a threat to the US GPS infrastructure? Does it not add another potential layer of redundancy for positioning systems? Assuming that the EU/NATO is still our ally...
The US has already leaned hard on European officials to abandon the €1.1bn (£772m) project.
Last year, the EU press spokesman for Galileo, Gilles Gantelet, declared that under the strain of American pressure, "Galileo is almost dead".
While US pressure has not killed off the Galileo project entirely, concessions made by European officials mean Galileo will now be a much weaker rival to GPS than the system they had envisioned.
https://www.theguardian.com/uk/2003/dec/08/world.internation...
Galileo will lead Europe into conflict with the US, which has security concerns about the building of a navigational network to rival its own system.
http://news.bbc.co.uk/2/hi/science/nature/1893022.stm
The United States has security worries about the development of Galileo.
http://news.bbc.co.uk/2/hi/business/3121682.stm
Last year, the EU press spokesman for Galileo, Gilles Gantelet, declared that under the strain of American pressure, "Galileo is almost dead".
While US pressure has not killed off the Galileo project entirely, concessions made by European officials mean Galileo will now be a much weaker rival to GPS than the system they had envisioned.
https://www.theguardian.com/uk/2003/dec/08/world.internation...
Galileo will lead Europe into conflict with the US, which has security concerns about the building of a navigational network to rival its own system.
http://news.bbc.co.uk/2/hi/science/nature/1893022.stm
The United States has security worries about the development of Galileo.
http://news.bbc.co.uk/2/hi/business/3121682.stm
The India program only started launching a couple years ago. Galileo has been launching since 2006. Perhaps the clocks fail only after x amount of hours in space or some other condition based on age. The oldest Galileo sat clock has a decade of wear on it. I imagine there are some worried people in the Indian space program right now after hearing this news.
From the article:
Most of the maser failures (5) have occurred on the satellites that were originally sent into orbit to validate the system, whereas all three rubidium stoppages are on the spacecraft that were subsequently launched to fill out the network.
Rubidium clock failures are being seen in "operational" Galileo satellites. First operational Galileo was launched in 2011.
And, first operational Indian navigational satellite was launched in 2013. So, there's not much difference in the timeline or aging of Rubidium atomic clocks between ESA and ISRO satellites.
Anyway, ISRO will be switching to indigenous atomic clocks for next generation navigation satellites[1].
[1] http://www.thehindu.com/news/national/tamil-nadu/india-devel...
Most of the maser failures (5) have occurred on the satellites that were originally sent into orbit to validate the system, whereas all three rubidium stoppages are on the spacecraft that were subsequently launched to fill out the network.
Rubidium clock failures are being seen in "operational" Galileo satellites. First operational Galileo was launched in 2011.
And, first operational Indian navigational satellite was launched in 2013. So, there's not much difference in the timeline or aging of Rubidium atomic clocks between ESA and ISRO satellites.
Anyway, ISRO will be switching to indigenous atomic clocks for next generation navigation satellites[1].
[1] http://www.thehindu.com/news/national/tamil-nadu/india-devel...
Most simple problems are weird if you hardware isn't accessible by any means, e.g. what do you do if it suddenly stops responding? You can't simply press the reset button, all you can do is wait and hope for the best. It's an engineers nightmare.
With functioning clocks, Galileo is accurate to within a metre, according to this article. That's crazy - I had no idea it was that accurate.
With India, China and Russia launching their own positionning systems, I wonder if it would be possible to interpolate an even higher precision by listening to all 5 signals at the same time.
(I don't know enough about signal processing to know if that's a possibility or not.)
(I don't know enough about signal processing to know if that's a possibility or not.)
Not only is it possible, it's already done in many (most?) smartphones made over the past few years, at least for the Russian GLONASS system. As China's BeiDou and Galileo become operational, those will presumably be incorporated too.
However, I'd guess that most of the improvement in user experience comes from the higher reliability than higher accuracy. Even if the errors from all systems were completely uncorrelated (which they are not), averaging the location reported by four systems gives you at most a factor of 2 in improved accuracy. On the other hand, if your chance of being able to lock onto enough satellites (within a given number of seconds) for one system is 80%, the chance that you can lock on to at least one of the four systems becomes 99.8%.
However, I'd guess that most of the improvement in user experience comes from the higher reliability than higher accuracy. Even if the errors from all systems were completely uncorrelated (which they are not), averaging the location reported by four systems gives you at most a factor of 2 in improved accuracy. On the other hand, if your chance of being able to lock onto enough satellites (within a given number of seconds) for one system is 80%, the chance that you can lock on to at least one of the four systems becomes 99.8%.
I'm having trouble to grasp how you get a factor 2 improved accuracy if you have data from four uncorrelated systems all having the same accuracy.
Where can I find more information about this?
Where can I find more information about this?
If your N samples are independent and distributed with the same error sigma, then the error of the averaged result is sigma/sqrt(N). (And of course, sqrt(4) = 2.)
You can calculate this directly by computing the variance of a sum of independent Gaussian random variables. Can't find a great link for further reading, but someone else might be able to help you out.
You can calculate this directly by computing the variance of a sum of independent Gaussian random variables. Can't find a great link for further reading, but someone else might be able to help you out.
I'm glad there are people who know what all this means so I can tap a button, say "navigate to the grocery store" to my phone, and not spend brain cycles learning and maintaining knowledge of the wide range of math/programming/engineering specialties I'd otherwise have to master.
Everyone should know the central limit theorem though, simply for its own sake! It's worth the brain cycles :)
https://en.wikipedia.org/wiki/Central_limit_theorem
https://en.wikipedia.org/wiki/Central_limit_theorem
I had an intuitive sense of this. People saying "half the population has a below average IQ!" always elicited a head tilt from me. I just didn't know there was enough to say on the subject to fill a 8k word wikipedia article.
I'll file this next to the formula I whip up when I want to figure out how much a trip costs based on mileage and fuel prices.
I'll file this next to the formula I whip up when I want to figure out how much a trip costs based on mileage and fuel prices.
It's sometimes important to actually work out the math to overcome cognitive biases and faulty intuition.
Phrasing the statement as "Think of how dumb an average person you meet on the street is. Now realize that half of all people are even more dumb than that." primes the brain to denigrate the intelligence of a random person, leading to a wrong conclusion.
Another example relates to your formula for fuel economy - some locales use distance-per-volume (miles per gallon) while others use volume-per-distance (liters per 100 km). Intuition may suggest that upgrading from a 15 mpg vehicle to a 20 mpg vehicle is comparable to going from a 30 mpg vehicle to a 35 mpg vehicle - but it's not! Using the reciprocal more accurately describes the emissions and costs related to different fuel economies over the wide range of values that you'll measure in modern vehicles: The example compares a 15.7 -> 11.6 L/100km change and a 7.8 -> 6.7 L/100km change. These units make it much easier to intuit the results.
Doing the math occasionally is a good habit to get into!
Phrasing the statement as "Think of how dumb an average person you meet on the street is. Now realize that half of all people are even more dumb than that." primes the brain to denigrate the intelligence of a random person, leading to a wrong conclusion.
Another example relates to your formula for fuel economy - some locales use distance-per-volume (miles per gallon) while others use volume-per-distance (liters per 100 km). Intuition may suggest that upgrading from a 15 mpg vehicle to a 20 mpg vehicle is comparable to going from a 30 mpg vehicle to a 35 mpg vehicle - but it's not! Using the reciprocal more accurately describes the emissions and costs related to different fuel economies over the wide range of values that you'll measure in modern vehicles: The example compares a 15.7 -> 11.6 L/100km change and a 7.8 -> 6.7 L/100km change. These units make it much easier to intuit the results.
Doing the math occasionally is a good habit to get into!
The intuition should be that "Half the population has below average X" is untrue for the vast majority of situations, because most real things have a skewed distribution.
AFAIK IQ is a peculiar case because of how IQ is defined.
AFAIK IQ is a peculiar case because of how IQ is defined.
A lot of natural processes produce results that are normally distributed. So given a large sample, a continuous value range, no bounds (or far away bounds) and a lack of obvious skew the intuition "half the population is below average" has a good chance to be (approximately) true.
Of course IQ is a made up thing that we just defined to behave that way.
Of course IQ is a made up thing that we just defined to behave that way.
Yes, the obvious counter-example is that almost the entire population has more than the average number of legs.
Haha an academic advisor of mine told me once that CLT was the only important thing I had learned that year.
I doubt uncorrelatedness. If the frequencies are very close then the systems share to some degree one source of error: ionospheric lightspeed variations.
[deleted]
In principle, a sufficiently smart device could lock onto one satellite of each system, and in the aggregate they'd be enough. But that would require some serious engineering.
It's not just precision, but availability of the signal and speed. Having more signals in natural and urban canyons improves accuracy and speed when there are more satellites.
One-chip GPS/GLONASS multiconstellation receivers have been on the market for some time. Millions of consumer units sold. Many smartphones have them.
Quad-constellation (GPS, GLONASS, Galileo, BeiDou) receiver chips have been on the market for some time.
For example: STA8090GA, It's automotive Grade GPS/Galileo/Glonass/Beidou/QZSS receiver
http://www.st.com/content/ccc/resource/technical/document/da...
One-chip GPS/GLONASS multiconstellation receivers have been on the market for some time. Millions of consumer units sold. Many smartphones have them.
Quad-constellation (GPS, GLONASS, Galileo, BeiDou) receiver chips have been on the market for some time.
For example: STA8090GA, It's automotive Grade GPS/Galileo/Glonass/Beidou/QZSS receiver
http://www.st.com/content/ccc/resource/technical/document/da...
> With India, China and Russia launching their own positionning systems, I wonder if it would be possible to interpolate an even higher precision by listening to all 5 signals at the same time.
First: Only Navstar-GPS, GLONASS and (in near future) Galileo will have worldwide coverage. Perhaps in future (but according to http://www.navipedia.net/index.php/BeiDou_Future_and_Evoluti... not before 2020) BeiDou will also have global coverage. IRNSS only has regional coverage.
So in near future we will only have three sources (not five).
Now for the simple mathematical trick: Model the position of the three systems as normal distributed random variable with same \mu, but different \sigma (\sigma_1, \sigma_2, \sigma_3). These three sigmas have to be measured. Now a convex combination of these random variables is again normal distributed, but with different \sigma (let's call it \sigma^* ) (easy exercise or look it up). Now just compute the coefficients of the convex combination that minimize \sigma^*.
First: Only Navstar-GPS, GLONASS and (in near future) Galileo will have worldwide coverage. Perhaps in future (but according to http://www.navipedia.net/index.php/BeiDou_Future_and_Evoluti... not before 2020) BeiDou will also have global coverage. IRNSS only has regional coverage.
So in near future we will only have three sources (not five).
Now for the simple mathematical trick: Model the position of the three systems as normal distributed random variable with same \mu, but different \sigma (\sigma_1, \sigma_2, \sigma_3). These three sigmas have to be measured. Now a convex combination of these random variables is again normal distributed, but with different \sigma (let's call it \sigma^* ) (easy exercise or look it up). Now just compute the coefficients of the convex combination that minimize \sigma^*.
Or you could just say that, for N independently distributed samples, the accuracy improves by a factor of at most sqrt(N) :)
This does only hold if the standard deviation \sigma is the same for all of the normal distributed variables. This is not the case here: Galileo is supposed to be more precise than Navstar-GPS (no surprise, since it is the newer system) - though I know that the US government is working on to increase the precision for Navstar-GPS. On the other hand (source: http://www.navipedia.net/index.php/GLONASS_Performances#GLON...) GLONASS is less precise than Navstar-GPS.
Well, I said "at most", so it holds for all sigma_i. As you know, when the sigma_i are very different, then the accuracy is approximately given by the best accuracy (smallest sigma_i), so there's very little improvement from averaging.
> Well, I said "at most",
OK, you are right. This can indeed be shown.
OK, you are right. This can indeed be shown.
(warning: armchair expert, I've just read a bunch of wikipedia pages)
I believe there's still sources of systemic error that would affect all the signals similarly, such as atmospheric interference, so even taking (for example) the average of the reported position from all the services may not improve accuracy that much.
https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_... is a good read.
I believe there's still sources of systemic error that would affect all the signals similarly, such as atmospheric interference, so even taking (for example) the average of the reported position from all the services may not improve accuracy that much.
https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_... is a good read.
The typical approach seems to be to consider all the visible satellites together (rather than solving for the position indicated by each constellation and averaging them).
So in practice having more satellites means that a good position measurement is possible more of the time.
So in practice having more satellites means that a good position measurement is possible more of the time.
You can also reduce some of the atmospheric interference by modeling it using both the L1 and L2 signal.
Apparently they wanted to make it even more accurate, but got pushback from USA before they feared it would be used by hostile forces.
I'm very disappointed that the EU bowed to their demands. It is the second clear sign I know that Europe dances to the USA's pipe; the other one was the grounding of the bolivian presidents plane in 2013.
I hope that Europe eventually stops giving in to demands by the USA.
[0] https://en.wikipedia.org/wiki/Evo_Morales_grounding_incident
I hope that Europe eventually stops giving in to demands by the USA.
[0] https://en.wikipedia.org/wiki/Evo_Morales_grounding_incident
Or maybe the European team simply agreed with the concern?
That is not the case. There was no valid concern.
GPS is US military. They can block access to the civilian one for any reason.
But if Galileo is on, they don't have the power to block it. Unless they jam its frequency. But as they use that same frequency, it would jam GPS. So, without officially giving a reason, they forced the EU to be on a different frequency.
There is no concern with using the same frequency. The US simply wants, and got, the ability to jam Galileo.
https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
GPS is US military. They can block access to the civilian one for any reason.
But if Galileo is on, they don't have the power to block it. Unless they jam its frequency. But as they use that same frequency, it would jam GPS. So, without officially giving a reason, they forced the EU to be on a different frequency.
There is no concern with using the same frequency. The US simply wants, and got, the ability to jam Galileo.
https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
Selective availability was disallowed by executive order in 2000. Block III satellites will not even have the capability to disable the civilian signal.
Now, that is a valid concern. So far the first I read. Maybe some countries in Europe also wanted to see Snowden catched.
Would there be a reason why GPS with 10m accuracy is OK but Galileo with 1m is not?
GPS has better than 10m accuracy in another operating mode. Only the military is allowed to use that one, though. Then they don't want Galileo being 1m accurate? Probably same military reasons.
> GPS has better than 10m accuracy in another operating mode. Only the military is allowed to use that one, though.
This has not been true since May 2000, when GPS "Selective Availability" was turned off. Civilian and military receivers have the same accuracy now.
http://www.gps.gov/systems/gps/modernization/sa/
This has not been true since May 2000, when GPS "Selective Availability" was turned off. Civilian and military receivers have the same accuracy now.
http://www.gps.gov/systems/gps/modernization/sa/
No, that's not true. The military has access to different codes and frequencies that aren't available for civilian use, which can be used to apply further corrections to the computed location. Selective Availability was not the only difference between civilian and military GPS.
https://www.quora.com/Is-there-any-difference-between-milita...
https://www.quora.com/Is-there-any-difference-between-milita...
As far as I understand, the remaining differences between military and civilian GPS don't matter much for accuracy. The military may still have the advantage of ionospheric correction, but civilians can use other augmentation systems like WAAS[1] with similar results. I think the military signals are mostly intended to protect against signal spoofing and jamming.
[1] https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System
[1] https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System
Thanks for that link. Never heard of it. That's some mind-blowing tech and accuracy.
Those extra frequencies were what I was thinking about. If they're still closed, then military still cripples GPS. The points of military vs civilian for this discussion would still apply.
I didnt know about that. Thanks for thd tip. So, the civilian GPS devices have the PPS signal and accuracy the military had?
Do you know of any examples when USA has stopped or changed its course on what can be considered its internal matters, or space area?
> It is the second clear sign I know that Europe dances to the USA's pipe
There are plenty more. My favourite: https://en.wikipedia.org/wiki/SWIFT#U.S._control_over_transa...
There are plenty more. My favourite: https://en.wikipedia.org/wiki/SWIFT#U.S._control_over_transa...
The US will stop pressuring the Europe once Europe has 10 or more carrier groups and an equal or so number of nuclear ballistic missiles.
This is actually untrue. The US didn't like that the EU was using bands close to GPS so if there was a conflict where the Russians or Chinese were using Galileo to target American troops, the US would have no choice but to shoot down or otherwise disable Galileo satellites by force. No one wants this, so the EU chose a different frequency that could be jammed without jamming GPS. Accuracy was never a concern. Galileo can't do better than a meter for many reasons, not the least of which is number of satellites, clock accuracy, and cost.
https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
Then Europe should treat shooting down of Galileo satellites as an act of war and react as such.
It's not Europes business to make it easy for the USA to wage war.
It's not Europes business to make it easy for the USA to wage war.
It's not about making it easy for the US. Shooting down satellites is not going to be a tough problem for the US military. It's about convincing the US not to do that.
It's like not leaving food out to avoid attracting bears. Sure, it would be nice if the bears would just not bother you in the first place. But you can't influence their behavior directly, you can only influence what you do.
It's like not leaving food out to avoid attracting bears. Sure, it would be nice if the bears would just not bother you in the first place. But you can't influence their behavior directly, you can only influence what you do.
It might be easy for the US to shoot down satellites, but so it might be for Europe.
The whole point of this story is that the USA wants to be able to act without Europe possibly having a say. That Europe agreed was wrong, I think.
The whole point of this story is that the USA wants to be able to act without Europe possibly having a say. That Europe agreed was wrong, I think.
My whole point is that the USA can act without Europe having a say, whether Europe likes it or not. It's only reasonable for Europe to take that into account in what they do.
You can take some principled stand to make some sort of abstract point nobody will understand, and have the USA shoot down your satellites in the case of war. Or you can make a small change to your design and have the USA leave them alone. I don't see why taking the second option is so terrible.
You can take some principled stand to make some sort of abstract point nobody will understand, and have the USA shoot down your satellites in the case of war. Or you can make a small change to your design and have the USA leave them alone. I don't see why taking the second option is so terrible.
If Europe had created Galileo like originally envisioned the USA could not jam Galileo without also jamming GPS. Hence they would need to ask Europe to turn of Galileo or turn Galileo off for them, i.e. shooting down the satellites, which Europe should treat as an act of war. Hence, neither of both options go without Europe having a say.
The abstract point here is akin to mutually assured destruction. It keeps peace.
Having Galileo like originally envisioned and Europe taking a robust defensive strategy w.r.t. to it's satellites would mean GPS for everybody or for nobody or war with Europe. And Europe should make sure nobody wants war with them.
The abstract point here is akin to mutually assured destruction. It keeps peace.
Having Galileo like originally envisioned and Europe taking a robust defensive strategy w.r.t. to it's satellites would mean GPS for everybody or for nobody or war with Europe. And Europe should make sure nobody wants war with them.
The frequencies were selected to allow for easy compatibility with GPS not because the EU didn't want the US to be able to selectively jam Galileo.
No one in Europe really thinks of a war with the US as a real possibility and since the know what ICBM stands for they also know they've lost before the first shot is fired.
No one in Europe really thinks of a war with the US as a real possibility and since the know what ICBM stands for they also know they've lost before the first shot is fired.
> and have the USA shoot down your satellites in the case of war.
And then we shoot down their satellites, too. The US acting like they can do whatever they want is extremely annoying and has to end, they’re just a country, not the king of the world.
And then we shoot down their satellites, too. The US acting like they can do whatever they want is extremely annoying and has to end, they’re just a country, not the king of the world.
> they’re just a country, not the king of the world.
Militarily and economically the US is an empire (by definition, as its growth is tied to warfare, expansion, and dominance). Just like the British empire was before it.
For example - it has 400 major, and another 400 minor, bases (some with nuclear-ready weapon systems) stationed in foreign countries. While no foreign country has a base in the US.
Militarily and economically the US is an empire (by definition, as its growth is tied to warfare, expansion, and dominance). Just like the British empire was before it.
For example - it has 400 major, and another 400 minor, bases (some with nuclear-ready weapon systems) stationed in foreign countries. While no foreign country has a base in the US.
It's like giving the bully your lunch so they leave you alone.
It's more like giving the bully his favorite seat. You can stand on principle, but the result will be more or less the same either way, and giving him what he wants doesn't hurt you.
I think bullies should be treated with confrontative aggressiveness wherever possible until they stop bullying.
That's a great strategy when you're a member of a society that mostly doesn't put up with bullying, and will ultimately be on your side if their aggression gets too much attention. It's a terrible strategy when you're living in an anarchy and the bully is as mighty as everybody else put together.
Yes. That's why I think a federal EU with united army and foreign policy stands a much better chance of achieving beneficial outcomes for its citizens.
The strategy is also great if you can guarantee the bully mutual complete destruction.
Of course, it cuts both ways.
With the constellations on different frequencies, European powers also have the ability to engage in localised GPS jamming while leaving Galileo available for their military.
With the constellations on different frequencies, European powers also have the ability to engage in localised GPS jamming while leaving Galileo available for their military.
Blowing up 1 or more satellites will also increase the amount of orbital debris floating around.
There is already something near 1 million pieces of space junk being actively tracked to avoid possible collisions with existing space vehicles/satellites.
This space junk problem eventually reaches a point where no orbital vehicles will be able to reach, stay in, and/or pass into space.
There is already something near 1 million pieces of space junk being actively tracked to avoid possible collisions with existing space vehicles/satellites.
This space junk problem eventually reaches a point where no orbital vehicles will be able to reach, stay in, and/or pass into space.
Europe is part of NATO and has major incentives to cooperate with the US. In the scenario where the US would have to shoot down Galileo sats, would most likely be one where the US is protecting Europe from China or Russia as we're talking WWIII. I imagine this little story is little more than a tempest in a teapot designed to enrage Euro nationalists. The reality is that when you're in a shared defense agreement, your weapons systems, including nav systems, need a high level of cooperation. A frequency shift isn't the tragedy you're making it out to be.
In the case of a hot war between the US and Russia, the first victims (of mushroom clouds) will be every single EU NATO member that hosts US bases and US nuclear weapons.
So I'm not quite sure what the gain is for those members as they will not survive (the US might, but they won't).
So I'm not quite sure what the gain is for those members as they will not survive (the US might, but they won't).
In the scenario you mentioned Europe could turn off Galileo if deemed necessary, no need for the USA to shoot it down. The solution taken just makes it easier for USA to wage war against Europes interests.
Europe isn't a single entity. Imagine a conflict in Eastern Europe that the US is part of. The rest of Europe has built its infrastructure on Galileo and shutting it down means major economic and infrastructure issues for Europeans not involved in the conflict. The US asks them to turn it off, but Merkel says no. Or Greece says no because Putin promised them $200m in aid. EU decisions have to be unanimous. Now what? Lets stop pretending European nations, even members of NATO, all care about each other. There's no polite discourse here. Just naked self-interest that's easy for the enemy to game.
Merkel might decide that she wants nothing to do with Russia taking Estonia, Romania, and Bulgaria. This is why we need technical solutions, not political ones. Banking on Europe being nice to each other is hilariously short-sighted and ahistoric.
Note, Europeans are free to leave NATO whenever they wish if they don't like our defense posture and technical requirements. I imagine letting the Russian military loose is probably not within Europe's self-interest, so enforcing technical requirements that protect all of Europe makes sense. It leaves less room for cowardly players like Merkel to appease expansionist dictators like Putin. If anything, the US did European security a favor with this policy.
Merkel might decide that she wants nothing to do with Russia taking Estonia, Romania, and Bulgaria. This is why we need technical solutions, not political ones. Banking on Europe being nice to each other is hilariously short-sighted and ahistoric.
Note, Europeans are free to leave NATO whenever they wish if they don't like our defense posture and technical requirements. I imagine letting the Russian military loose is probably not within Europe's self-interest, so enforcing technical requirements that protect all of Europe makes sense. It leaves less room for cowardly players like Merkel to appease expansionist dictators like Putin. If anything, the US did European security a favor with this policy.
What is an enemy for the USA might not be an enemy of Europe. I can just repeat myself. If it is in the interest of Europe to turn Galileo off, they can do so. If it is not in their interest, they shouldn't do so. Now, that the decision making in the EU is inefficient might be an _internal_ issue that needs to be solved, not be workedaround by giving the USA the final say.
> EU decisions have to be unanimous.
That's not true.
That's not true.
> Europe is part of NATO
Some of Europe is. Austria, Cyprus, Finland, Ireland, Malta, Sweden etc aren't.
Some of Europe is. Austria, Cyprus, Finland, Ireland, Malta, Sweden etc aren't.
You are being pedantic for no reason neither of those nations is a substantial military power.
Except Cyprus they're all in the PfP program though: http://www.nato.int/cps/en/natolive/topics_82584.htm
Austria, for example, participated in missions in Africa, Afghanistan, the Balkans (KFOR, etc).
You really should learn about the subject you're trying to argue about.
Austria, for example, participated in missions in Africa, Afghanistan, the Balkans (KFOR, etc).
You really should learn about the subject you're trying to argue about.
PfP isn't a mutual defense agreement, it's more like lets play airsoft together.
Hence Russia is a participant, not exactly a NATO membership candidate or ally.
Treating an ally shooting down your satellites because those satellites are being used against them as an act of war is pretty short sighted.
Purposely designing your satellites in order to force them to do so in the event of a war is even more short sighted.
If American satellites were being used to guide missiles at Europe, you'd be pretty PO'd.
Purposely designing your satellites in order to force them to do so in the event of a war is even more short sighted.
If American satellites were being used to guide missiles at Europe, you'd be pretty PO'd.
So rather than make a technological change, which according to the parent post has no effect on the quality of the end system, Europe should wage war on the US if the US did something aggressive to protect it's troops in the middle of what I assume would already be World War 3? (an overt conflict with Russia or China?)
If whatever the USA are planing to do is in Europes interest, they can ask to turn Galileo off. If it is really in Europes interest, they will do so.
Localized jamming sounds a lot less disruptive than turning off the system for the entire world.
You could also turn off Galileo only in some areas.
No you can't.
Why shouldn't it be possible to turn off only those satellites that are visible in a certain area? I don't see any argument in your favour.
Wouldn't this cripple the system over a much wider area than intended? The are from which a satellite in LEO is visible is ~5000km in diameter.
Galileo isn't in LEO https://en.wikipedia.org/wiki/Medium_Earth_orbit but yes, shutting off the signal would mean that a radius of about 7000 (GPS sats can be seen across about 6500~ miles depending on the exact orbit and angle, Galileo will have more coverage since they are at a higher orbit, if you really want to know here is how you calculate it http://gis.stackexchange.com/questions/77651/how-to-find-rin...) miles has no SatNav...
Jamming can shut down GPS in any range from 10M to 100,000M turning the transmitters of effectively shuts down GPS to half the globe. ]
Jamming can shut down GPS in any range from 10M to 100,000M turning the transmitters of effectively shuts down GPS to half the globe. ]
[deleted]
You realize that most of Europe is in NATO with the US, right?
What's the fear with more accuracy?
From my (completely layman) perspective once you've got a meter or so of accuracy, you've got what you need for weapons.
What's further accuracy get you that some nations are against everyone having?
From my (completely layman) perspective once you've got a meter or so of accuracy, you've got what you need for weapons.
What's further accuracy get you that some nations are against everyone having?
A similar thing happens with commercial imagery satellites. Companies are forced to downsample their high resolution govt-only images to 30cm for the general public.
That's slightly different though, better imagery makes it possible to resolve more features.
With the improved positional accuracy it's a 2 meter circle vs a 1 meter circle. What tactics does a 1 meter circle enable that the 2 meter circle does not enable?
Also, DigitalGlobe only has 30 cm capability:
https://en.wikipedia.org/wiki/WorldView-4
Who is downsampling (DigitalGlobe/GeoEye was downsampling earlier 40 cm imagery for Google, to 50cm)?
With the improved positional accuracy it's a 2 meter circle vs a 1 meter circle. What tactics does a 1 meter circle enable that the 2 meter circle does not enable?
Also, DigitalGlobe only has 30 cm capability:
https://en.wikipedia.org/wiki/WorldView-4
Who is downsampling (DigitalGlobe/GeoEye was downsampling earlier 40 cm imagery for Google, to 50cm)?
My understanding is that it's not exactly "by force" but rather a condition of funding. The U.S. Government is probably Digital Globe's largest customer.
No, it is by force. It is similar to ITAR regulations. If you break that rule, your management team is probably going to jail. It would be akin to spying for a foreign power. Source: I used to do some consulting for a satellite imagery company.
[deleted]
There's no fear about accuracy - the plan is that Galileo will charge for high precision services. Indeed, you can buy centimeter-precision GPS services right now for applications like surveying and precision farming [1] - those are small markets, of course; self-driving cars are the real prize.
The objection from the US amounted to the fact an early Galileo design would have reduced their ability to degrade satellite navigation in war zones. Later the design was changed, so the US can jam Galileo - which avoids the US objection, but makes Galileo less useful as a backup.
[1] http://www.trimble.com/Positioning-Services/Trimble-RTX.aspx
The objection from the US amounted to the fact an early Galileo design would have reduced their ability to degrade satellite navigation in war zones. Later the design was changed, so the US can jam Galileo - which avoids the US objection, but makes Galileo less useful as a backup.
[1] http://www.trimble.com/Positioning-Services/Trimble-RTX.aspx
To me that's surprisingly inaccurate. With a corrected system, no ground reference data, we can get 10cm RMS, no?
With appropriate ground corrections 5 cm is pretty easy with the current US satellites. Sub-meter in real time is also fairly easy with the help of WAAS broadcasts and good receivers. But if consumer hardware (like a typical $200 Garmin receiver) could reliably have sub-meter accuracy that would be a big improvement. But I'm no expert on the actual math of GPS.
Anyone around here know details on the encryption used by Galileo, Beidou, and GPS? Google does not turn up much. It would be interesting to hear about how they're doing this.
With the constraints that they have (receivers not necessarily always online to receive key updates, extremely low bandwidth to work with, systems depend heavily on this information, fast locks are important) it would not surprise me if the encryption scheme has big holes in it.
On the other hand, some of these constraints can be dealt with by making receivers fall back to the unencrypted signal until they're locked long enough to get their new keys. And given that this is military, they might err on the side of security rather than accessibility. So who knows.
With the constraints that they have (receivers not necessarily always online to receive key updates, extremely low bandwidth to work with, systems depend heavily on this information, fast locks are important) it would not surprise me if the encryption scheme has big holes in it.
On the other hand, some of these constraints can be dealt with by making receivers fall back to the unencrypted signal until they're locked long enough to get their new keys. And given that this is military, they might err on the side of security rather than accessibility. So who knows.
Is there a way to fix such problems with a software update?
We won't know until we know what's the cause in the first place.
The article says that after some troubleshooting they were able to restart one of the hydrogen maser clocks, so it appears they do have some abilities on the software side.
It sounds like a manufacturing issue to me, so I don't think so. The batch they ordered could have been faulty, but I'm assuming that ESA uses samples taken from multiple runs to minimize failures, so that's fairly unlikely.
It could be a design issue too. Like are they accidentally over-voltaging the clock with a transient or some sort of power sequencing issue? Or does some component have tin somewhere? Really hard to say at this point.
I really hope it's not a design issue, but that could definitely be the case. Why tin specifically?
Tin forms whiskers, small hairlike growths on the metal that can cause short circuits. We've already lost a satellite to this phenomenon, although I would hope it's not a problem anymore with current metallurgical techniques
https://en.wikipedia.org/wiki/Whisker_(metallurgy)
https://en.wikipedia.org/wiki/Whisker_(metallurgy)
If I remember right, tin whiskers were determined to be the cause in the crazy Toyota runaway accelerator pedals a few years back. I think it's mainly an issue with lead-free solders, which RoHS has forced into widespread usage over the last decade.
It was hypothesized, but not accepted as a cause: http://www.autonews.com/article/20120727/OEM11/120729908/nht...
The problem was ultimately found to be a combination of pedals being pressed by floor mats, pedals sticking on their own, and drivers pressing the wrong pedal.
The problem was ultimately found to be a combination of pedals being pressed by floor mats, pedals sticking on their own, and drivers pressing the wrong pedal.
ESA is not part of the EU -- it's an international organization, and is exempt from national law in the same way as an embassy. Even if RoHS applies to spacecraft, it probably doesn't apply to ESA's spacecraft.
That's not to say acquiring non-RoHS components isn't made more difficult by RoHS.
That's not to say acquiring non-RoHS components isn't made more difficult by RoHS.
RoHS does not apply to spacecraft. In fact, companies specialize in things like replacing RoHS solder balls on BGA parts with lead solder ones.
Some some comments on the military in Aerospace issues with RoHS - with photos:
http://www.militaryaerospace.com/articles/print/volume-20/is...
http://www.militaryaerospace.com/articles/print/volume-20/is...
Just in case, the NASA page dedicated to the matter:
https://nepp.nasa.gov/whisker/index.html
https://nepp.nasa.gov/whisker/index.html
tomasbrown(1)
/r/conspiracy: The CIA probably fed them bad components or software for the clocks. Higher levels of positioning accuracy is potentially dangerous and can be misused by third parties, so the argument goes.
/r/conspiracy: #2 The CIA is downvoting this post.
/r/conspiracy: #2 The CIA is downvoting this post.
[deleted]
Its surprisingly difficult to find real, detailed data about the GPS system. The block II first production run of GPS sats that were launched around 1990 and decommissioned in at most 17 years had a design life of a pitiful 7 years and used dual Rb clock and Cs clocks. I'm not sure the modern block details are declassified. Anyway the failure rate for Galileo seems consistent with a "less than a decade design life" I'm not sure block IIIa is even finished designing yet.
People have this peculiar idea that "the gps satellite" was launched one time in the 80s and its been running ever since... not so, gosh there must have been a hundred or so launched over the last couple decades.
I have some limited experience with Rb-standards and on the ground in telco land you'll get an amazing song and dance from the mfgr about how in theory they should run for eternity but being a vacuum tube (actually conceptually closer to a fluorescent light) they do wear out and end up on ebay after a decade or so for ham radio microwave and EME operators to do peculiar things with them cheaply. Not good enough to run a data center is still stable enough to help bounce signals off the moon.
I have no experience with hydrogen standards they don't even appear on ebay in my price range. Again perhaps its normal for them to wear out, etc.
So Rb standards "should" die off on a regular basis. Possibly the biggest classified secret of the entire GPS project MIGHT be you have to massively overspec your clocks or you get an economic kill shot of spending a billion bucks (rubles, euros) on something that only runs six months LOL shoudda just licensed our technology that learned the lessons the hard way in developmental block I satellites in the mid 80s.