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NASA Finds Cause of Voyager 2 Glitch

kdawson posted more than 4 years ago | from the blame-cosmic-rays dept.

Bug 283

astroengine writes "Earlier this month, engineers suspended Voyager 2's science measurements because of an unexpected problem in its communications stream. A glitch in the flight data system, which formats information for radioing to Earth, was believed to be the problem. Now NASA has found the cause of the issue: it was a single memory bit that had erroneously flipped from a 0 to a 1. The cause of the error is yet to be understood, but NASA plans to reset Voyager's memory tomorrow, clearing the error."

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Sometimes, if you do things right... (5, Funny)

BlackErtai (788592) | more than 4 years ago | (#32261368)

Nobody knows you've done anything at all.

good job (0)

Anonymous Coward | more than 4 years ago | (#32261438)

+1 Futurama reference

Re:Sometimes, if you do things right... (1)

jamesh (87723) | more than 4 years ago | (#32261646)

That is one of my favorite quotes from Futurama!

Re:Sometimes, if you do things right... (5, Funny)

angelwolf71885 (1181671) | more than 4 years ago | (#32261678)

like burning down a bar for the insurance money

Re:Sometimes, if you do things right... (0, Redundant)

thhamm (764787) | more than 4 years ago | (#32262252)

"So, do you know what i'll do before i do it?"
"Yes."
"And if i do something different?"
"Then i don't know that."
"Cool, cool ..."

Really? (3, Insightful)

atomicthumbs (824207) | more than 4 years ago | (#32261370)

The cause of the error is yet to be understood

Let me guess: cosmic ray. Is it really that hard? What else causes a single bit-flip error in space?

Re:Really? (2, Insightful)

srothroc (733160) | more than 4 years ago | (#32261406)

Age? Voyager is hardly brand new.

Just incredible! (3, Insightful)

mcrbids (148650) | more than 4 years ago | (#32261636)

Voyager is anything but brand new. Voyager is probably older than most Slashdotters, having been launched in 1977. Think about it: 1977 - when advanced microchips were not as powerful as the chip driving the shatty calculator you buy today at the dollar store. 1977 was a different time, when information technology usually didn't even involve transistors, yet, and vacuum tube testers (for your TV) were still found at the local drug store.

And yet, some 33 years later, Voyager 2 is still chugging on, after visiting ALL of the outer planets, still going waaayayyyyyyy past its original design limits, still providing meaningful information on its way out roughly towards the star Sirius. It's now twice as far away from the Sun as Pluto is.

Like the Mars rovers, this is truly good engineering at work.

Re:Just incredible! (0)

Anonymous Coward | more than 4 years ago | (#32261676)

> 1977 was a different time, when information technology usually didn't even involve transistors, yet

Uh...the last vacuum-tube computer was sold in the 1950s.

Re:Just incredible! (5, Informative)

fdrebin (846000) | more than 4 years ago | (#32261792)

1977 was a different time, when information technology usually didn't even involve transistors, yet, and vacuum tube testers (for your TV) were still found at the local drug store.

Tube testers were pretty darned hard to find almost anywhere in 1977 (you could find them in old-used-electronics stores). I do recall testing tubes in drugstores in the early 70's.

Solid state, and even (*gasp*) integrated circuits were in widespread use. Why, by gosh by golly, we even had *8080*'s then.

I was a senior in college in physics+EE; I and a handful of my fellow students managed to coerce one of the EE profs to take a few hours and teach us about tubes (they had been removed from the curriculum). For the most part the interest was for us audio-nerds... tubes had that nice desirable sweet sound... (but I digress)

/F

Re:Just incredible! (5, Insightful)

Hurricane78 (562437) | more than 4 years ago | (#32262264)

tubes had that nice desirable sweet distortion...

There, fixed that for ya...

Re:Just incredible! (0)

Anonymous Coward | more than 4 years ago | (#32262382)

hmmm I live in Canada and even my local corner store (typical place to find them) had a tester in the late 70's and even into the 80's... I'm guessing by the mid 80's they finally realized nobody was buying anything from the rack of tubes that were gathering dust underneath.... but I do recall somewhere in that era... near the end... taking a tube from an old radio in to see if it worked.

Re:Just incredible! (1)

lul_wat (1623489) | more than 4 years ago | (#32262158)

Radioactives, baby.

New-fangled memory (5, Informative)

dfsmith (960400) | more than 4 years ago | (#32262302)

One of the upgrades the Voyagers had over the Viking computers was CMOS memory (instead of plated wires). Read all about it at http://history.nasa.gov/computers/contents.html [nasa.gov] Apparently, there was some debate at the time over whether these new-fangled memories would be reliable.

Re:Just incredible! (1)

dugeen (1224138) | more than 4 years ago | (#32262362)

The thought of Voyager still on its way is an inspiring one. I can't visualise it without hearing the opening notes of the original Star Trek theme.

Re:Really? (5, Insightful)

pclminion (145572) | more than 4 years ago | (#32261412)

Let me guess: cosmic ray. Is it really that hard? What else causes a single bit-flip error in space?

When you have a probe billions of miles from Earth, with no hope of ever physically retrieving it, and something weird happens, I don't think the first thing you do is start making assumptions.

Re:Really? (3, Insightful)

Peach Rings (1782482) | more than 4 years ago | (#32261486)

It's pretty amazing that they even were able to track the problem down to a particular bit. No general purpose operating system has anything even remotely having dreams of approaching that level of reliability and stability. It's nice to see the strengths of bare-metal hacking demonstrated in this bleary age of big-button-pushing Java and .NET.

Re:Really? (4, Insightful)

BitZtream (692029) | more than 4 years ago | (#32261536)

Its also extremely important to note that not a single item you own is made to the specifications that Voyagers were made, even though made over 30 years ago.

Its also rather important to note that as unstable as most OSes are, they are several million times more complex than the code Voyager 1 and 2 run.

Finally, joke about Windows all you want ... if you do a default installation of Windows and you don't install any additional drivers or software, it is extremely stable and will just sit there for ages happy to do nothing but tick away.

Its also entirely feasable to find 1 stuck or flipped bit even using Java and .NET, you just have to actually understand the inner workings of this code which is not something pretty much any developer working in these environments has time to do these days.

Both things may be computers that run code and use electricity to do so, but thats about where the shared bits end. These guys have been using the same code for 30+ years ... they kinda know how it works and all its quirks at this point.

With all that said ... you're still right, its freaky impressive.

Re:Really? (1)

sznupi (719324) | more than 4 years ago | (#32261572)

Impressive how they established this one bit with certainty - a command for transmitting back, basically, RAM content? Or at least checksums for various parts of it, narrowing down the location? (what about the storage from which it will be restored?) Would that even work considering the gibberish transmitted?

If that was determined based largely on a copy at hand - what if some other bit is also wrong?...

Re:Really? (3, Interesting)

rew (6140) | more than 4 years ago | (#32261832)

Certainty? I don't think so.

I think they simulated Voyager with this bit flipped and saw the same output (that is transmitted to earth).

I hope they tried to flip ALL bits, and found that only this one bit would give the results seen. If you would follow the code and find and test just a few likely places, I'd expect a few more unexpected places to give the same results.

The quick fix is to send the correct byte to the craft and hope that fixes it. If the bit has become stuck in the new position, they will have to do a remote firmware upgrade (with the code rewritten to fit the stuck-at value...) Other memory cells may have broken down in the mean time, but with a stuck-at value that is correct for the current version of the firmware, which you won't know until you try them....

Re:Really? (2, Informative)

God of Lemmings (455435) | more than 4 years ago | (#32262148)

I would imagine that it was relatively easy. Voyager has not only a small amount of memory (about 541kb) about 10% of the command system's memory is dedicated to fault protection. Read here: Jet Propulsion Laboratory [nasa.gov]

Re:Really? (2, Funny)

dakameleon (1126377) | more than 4 years ago | (#32261804)

Finally, joke about Windows all you want ... if you do a default installation of Windows and you don't install any additional drivers or software, it is extremely stable and will just sit there for ages happy to do nothing but tick away.

Let me just OT for a moment here: if you didn't install any drivers or software... it'd just sit there, period, and you wouldn't be too happy about this slightly warm expensive paperweight you just bought. What on earth is the point of a computer without additional software?

Re:Really? (1)

Jugalator (259273) | more than 4 years ago | (#32262006)

The comparison is against Voyager that also have software installed, but where Windows is so much more complex and still with potential to run that stable. But yes, of course that complexity also drives the hw requirements.

Re:Really? (0)

Anonymous Coward | more than 4 years ago | (#32262096)

The point is that a bare Windows system is already much more complex and performs many more calculations than the Voyager computer, yet it still runs perfectly stable. That last bit I don't actually believe though. I would not trust a Windows system to run until 2040 without a critical problem which requires hands-on maintenance.

Re:Really? (1)

GigaplexNZ (1233886) | more than 4 years ago | (#32262284)

I would not trust a Windows system to run until 2040 without a critical problem which requires hands-on maintenance.

I doubt that this is the first time they've had to perform diagnostics or maintenance on Voyager.

Re:Really? (1, Insightful)

Anonymous Coward | more than 4 years ago | (#32262048)

I've diagnosed a single bit-error in a system with 1GB RAM based on the corruption it created in files. That bit error even was intermittent, with only a selection of surrounding bit patterns triggering it and then not all the time. It is not magic, folks. You look at the data which deviates from the expectations and look for patterns. Then you use your knowledge of how the system works to establish theories about the possible causes and finally you run tests to see if the kind of deviation occurs that the suspected cause would trigger.

Re:Really? (2, Funny)

IWannaBeAnAC (653701) | more than 4 years ago | (#32262236)

Finally, joke about Windows all you want ... if you do a default installation of Windows and you don't install any additional drivers or software, it is extremely stable and will just sit there for ages happy to do nothing but tick away.

Yeah, the problems only come when you try to use the keyboard or mouse.

Re:Really? (5, Informative)

0123456 (636235) | more than 4 years ago | (#32261602)

It's pretty amazing that they even were able to track the problem down to a particular bit.

To be fair, Voyager doesn't have many bits in its memory :). Tracking down a bad bit is much easier when you have 4k of RAM than when you have 4GB of RAM.

Re:Really? (1, Funny)

Anonymous Coward | more than 4 years ago | (#32261624)

One could argue it's about a million times easier

Re:Really? (2, Funny)

Anonymous Coward | more than 4 years ago | (#32261670)

1048576 times easier, you mean. we don't want your SI kind here.

Re:Really? (0)

Anonymous Coward | more than 4 years ago | (#32261816)

Then don't use SI prefixes.

Re:Really? (1, Funny)

Anonymous Coward | more than 4 years ago | (#32261884)

we use a binary postfix that is identical to a SI prefix

Re:Really? (1)

GigaplexNZ (1233886) | more than 4 years ago | (#32262288)

Clearly you missed the word "about".

Re:Really? (0)

Anonymous Coward | more than 4 years ago | (#32261864)

Anyway, it ought to be enough for everybody!

Re:Really? (1)

rew (6140) | more than 4 years ago | (#32261782)

It's happened before. Last time they just rearranged the code so that the particular bit that had become stuck-at-0 was required to be 0. Might have been a mars mission and not voyager.

Re:Really? (1)

rew (6140) | more than 4 years ago | (#32261724)

I can hope, can't I?

Re:Really? (0)

Anonymous Coward | more than 4 years ago | (#32262270)

That and they design these things specifically for operation in space. Single bit upsets SHOULD NOT be a problem which is probably why they are confused.

Re:Really? (3, Funny)

mozumder (178398) | more than 4 years ago | (#32261420)

Let me guess: cosmic ray. Is it really that hard? What else causes a single bit-flip error in space?

Incredibly annoying alien hackers?

Re:Really? (1)

Monkey-Man2000 (603495) | more than 4 years ago | (#32261668)

Let me guess: cosmic ray. Is it really that hard? What else causes a single bit-flip error in space?

Incredibly annoying alien hackers?

That's what I heard, and through a very reliable source [theonion.com]

Re:Really? (4, Funny)

sznupi (719324) | more than 4 years ago | (#32261464)

V'Ger is unwilling to just transfer the data to its Creator...

Re:Really? (1)

angelwolf71885 (1181671) | more than 4 years ago | (#32261694)

and people think it will be the robots WE are building that will enslave us

Re:Really? (3, Funny)

Anonymous Coward | more than 4 years ago | (#32261556)

Actually it was a metric "0" that got switched to an imperial "1".

Re:Really? (4, Funny)

ianezz (31449) | more than 4 years ago | (#32261580)

M-x butterfly [xkcd.com] . Cosmic rays, but on purpose.

Re:Really? (2, Funny)

T Murphy (1054674) | more than 4 years ago | (#32261614)

A tiny cosmic spatula.

Re:Really? (1)

rjch (544288) | more than 4 years ago | (#32261672)

Let me guess: cosmic ray. Is it really that hard? What else causes a single bit-flip error in space?

  • Age of equipment.
  • Electrical short.
  • Space debris.
  • Alien hackers.

Pick one. Any one.

Re:Really? (2, Interesting)

rew (6140) | more than 4 years ago | (#32261998)

  • Age of equipment.

You're the second one to suggest "age". When humans die of age, that's some failure in the human body that's common when people grow old. That's when we say someone died of old age. However when human made devices die, there is always a component that has failed. When you have a 5 year old mobile telephone that dies, you say it died of old age, and replace it. That's because you don't care and replacing it costs less than finding out the root cause for the failure.

When a properly designed computer flips a bit, SOMETHING happened. We may never know, it might have been a cosmic ray. But don't you think that they would use space-certified RAM chips for such a project?

In any case, I don't know what memory technology voyager uses. The (slightly) more modern space shuttles used magnetic core memory for essential systems. These are not affected by cosmic rays. If it isn't magnetic core, then it is likely to be static RAM. This too is not easily modified by a cosmic ray. Modern DRAM however is easily affected by cosmic rays. But exactly because of that, it's not likely that they used DRAM.

In 1977, when the voyagers were launched, DRAM had been commercially available for 7 years.... This might have been too new for NASA to design into their new babies....

Re:Really? (2, Informative)

Tapewolf (1639955) | more than 4 years ago | (#32262296)

In any case, I don't know what memory technology voyager uses. The (slightly) more modern space shuttles used magnetic core memory for essential systems. These are not affected by cosmic rays. If it isn't magnetic core, then it is likely to be static RAM. This too is not easily modified by a cosmic ray.

I got curious and looked it up: http://voyager.jpl.nasa.gov/faq.html [nasa.gov]

...apparently it uses Plated Wire memory [wikipedia.org] which I had not heard of before, but seems to be a relative of core store.

Re:Really? (1)

lul_wat (1623489) | more than 4 years ago | (#32262188)

Select 0
Select 0
Select 0
Select 0

Guys, there's something wrong.

Re:Really? (1)

Rivalz (1431453) | more than 4 years ago | (#32261758)

Y2K

Re:Really? (1)

Dthief (1700318) | more than 4 years ago | (#32261940)

alien hackers

Re:Really? (1)

Zoxed (676559) | more than 4 years ago | (#32261986)

>> The cause of the error is yet to be understood

Just to clarify: this was the submitters comment: it does not appear in the source article.

Re:Really? (1)

stealth_finger (1809752) | more than 4 years ago | (#32262234)

Cosmic Rays? Don't be so silly. It was obviously the Gremlins.....in SPAAAAAAAAACE!

There's. some. one, on the extendable boom.......some. thing. on the boom!

Cosmci Ra (0)

the roAm (827323) | more than 4 years ago | (#32261374)

What else would it be?

Re:Cosmci Ra (1)

the roAm (827323) | more than 4 years ago | (#32261384)

Should read cosmic radiation. Obviously I have also been affected.

Re:Cosmci Ra (4, Funny)

VValdo (10446) | more than 4 years ago | (#32261436)

What else would it be?

According to some German, aliens [thefirstpost.co.uk] .

W

PS is "Cosmci Ra" related to Mumm-Ra? Or She-Ra for that matter?

Have you tried..... (0)

qwerty8ytrewq (1726472) | more than 4 years ago | (#32261394)

Nice to know even the Rocket Scientists just turn it off and on again. At least they were clever enough to allow themselves access to the system, rather than having to come up with some workaround, like waiting for it to go into a planet's shadow to power down.

Re:Have you tried..... (2, Informative)

atomicthumbs (824207) | more than 4 years ago | (#32261402)

the voyager probes use a radioisotope thermoelectric generator so that wouldn't work anyway

Re:Have you tried..... (2, Funny)

EdZ (755139) | more than 4 years ago | (#32261454)

"Blow in the DTR!" "No, no! Jiggle the CCS!" "Did you try uninstalling the MGA?"

Re:Have you tried..... (2, Funny)

Volante3192 (953645) | more than 4 years ago | (#32261542)

All that and no "Try SCE to aux"?

Re:Have you tried..... (1)

ajclements (1529359) | more than 4 years ago | (#32261794)

Yeah, but Pete Conrad isn't on the craft to respond with a "What the hell is that?"

Re:Have you tried..... (0)

Anonymous Coward | more than 4 years ago | (#32261498)

the voyager probes use a radioisotope thermoelectric generator so that wouldn't work anyway

Wow, this is why science really makes me stop and think every once in a while.

More of an interested hobbyist, rather than amateur or pro, but that sounds very futuristic to me, and it's over 30 years old!

Re:Have you tried..... (0)

Anonymous Coward | more than 4 years ago | (#32261546)

The fancy words simply mean "it generates electricity from heat from radioactive decay". Wikipedia, as usual, has an informative article [wikipedia.org] on it.

Re:Have you tried..... (0)

Anonymous Coward | more than 4 years ago | (#32261876)

And it basically consist of only four different part.
lead shielding
radioactive hot stuff
peltierelement
heatsink

The heatsink can also work as shielding.

Re:Have you tried..... (1)

sznupi (719324) | more than 4 years ago | (#32261520)

the voyager probes use a radioisotope thermoelectric generator so that wouldn't work anyway

Plus you wouldn't want it to work that way - planetary encounters are mighty interesting. They were the main reason for existence of Voyagers in the first place...

Re:Have you tried..... (1)

lxs (131946) | more than 4 years ago | (#32261990)

That and the Sun being fainter than a full moon on Earth when seen from that distance make solar panels rather impractical.

Re:Have you tried..... (1)

sznupi (719324) | more than 4 years ago | (#32262064)

In Voyager-like mission, sure. But in some cases which were until recently a no-go, it's "...made solar panels rather impractical", not strictly "make". At least for missions to Jupiter; they will use solar panels soon (and I wouldn't be too surprised if the progress in solar panels gave us that at Saturn at least, at some point)

So.... reboot? (5, Funny)

superdave80 (1226592) | more than 4 years ago | (#32261408)

Why don't they just always try that first?

Re:So.... reboot? (1, Funny)

Anonymous Coward | more than 4 years ago | (#32261422)

It doesn't work unless you hit f8 and go into safe mode.

Re:So.... reboot? (2, Insightful)

the roAm (827323) | more than 4 years ago | (#32261424)

Because if it had been something else, rebooting could have done more harm than good.

Re:So.... reboot? (5, Insightful)

Brett Buck (811747) | more than 4 years ago | (#32261466)

Why don't they just always try that first?

        Because sometimes it doesn't come back on again.

      Brett

Re:So.... reboot? (1)

L4t3r4lu5 (1216702) | more than 4 years ago | (#32262300)

Pfff, typical engineers. Having Shutdown next to Reboot is very efficient, but not very fault tolerant.

Re:So.... reboot? (4, Funny)

llvllatrix (839969) | more than 4 years ago | (#32261582)

Dude, uptime blog cred!

Re:So.... reboot? (0)

Anonymous Coward | more than 4 years ago | (#32261844)

33 year uptime. Do. not. want. to. restart!

Re:So.... reboot? (4, Funny)

PePe242 (1690706) | more than 4 years ago | (#32261594)

Hello IT, ... have you tried turning it off and on again?

What!? No parity checking?! (1, Funny)

Anonymous Coward | more than 4 years ago | (#32261430)

Finally, we found a use for ECC RAM!

Must suck waiting 26 hours to find out if the reboot worked...

Re:What!? No parity checking?! (3, Funny)

mjwx (966435) | more than 4 years ago | (#32261916)

Must suck waiting 26 hours to find out if the reboot worked...

Nah, thats just like rebooting a Windows 2003 server. 14 days and it's still "Applying Computer Settings"

0 Post!!!!! (0, Offtopic)

Overkill Nbuta (1035654) | more than 4 years ago | (#32261444)

0 Post!!!!!!

33 years and still going strong - nuclear FTW (4, Insightful)

blind biker (1066130) | more than 4 years ago | (#32261488)

This is why you DO WANT nuclear energy in space! OK, Voyager 1 and 2 have RTGs, but even those are considered politically incorrect these days, especially such massive ones as in the Voyagers.

More nuclear power in spacecraft, I say. To provide propulsion (ion drive, or even better, explosive drive) and energy when far from the Sun. Fuck PC.

Re:33 years and still going strong - nuclear FTW (0)

Anonymous Coward | more than 4 years ago | (#32261626)

This is a sign of a much bigger problem: democracy in science and engineering. Be it climate research, paleobiology or space research - the decisions should be made using sound scientific / engineering reasoning, not on the basis of whoever shouts the loudest / has more clout wins. Science is awesome because even if everyone believes in hypothesis, it does not make it automatically to be true.
Unfortunately, we all see how it is working out: PETA wants to ban bio-research on animals, RTGs in space being a huge no-no. Don't even get me started on the regulations involved in doing the really cool next-gen stuff: non-clinical human research (like implants), panicky fear of any genetic modifications, etc. etc.

Re:33 years and still going strong - nuclear FTW (2, Informative)

eclectro (227083) | more than 4 years ago | (#32262058)

Politically incorrectness is not what is stopping RTGs from being launched, but lack of supply of plutonium 238 [discovery.com] . It's difficult to protest launches with radioactive elements because they all have been successful. And if one were to crash, the RTGs are sealed so there would not be any leakage. Unfortunately environmentalists want to protest anything radioactive, even though such criticisms may no longer be valid.

Re:33 years and still going strong - nuclear FTW (0)

mjwx (966435) | more than 4 years ago | (#32262120)

This is why you DO WANT nuclear energy in space!

Things go wrong and you say that this is a reason why people DO WANT nuclear power in space?

Something is so very, very wrong with your reasoning. If NASA couldn't fix the problem we wouldn't just have a bit of space junk spewing out garbage transmissions, we'd have a bit NUCLEAR space junk spewing out garbage transmissions.

explosive drive

That is a very bad idea for two reasons (assuming you're referring to project Orion and not completely off your tree). 1. Nuclear bombs are very heavy and very destructive, not only do you have the cost of getting them up there but you also have the very real possibility of them being detonated at slightly the wrong angle or slightly the wrong distance vaporising the craft (we are talking about NUCLEAR fucking bombs people) or any of the myriad of other unpredicted problems you will encounter in deep space. 2. Once out in space, you do not need continual propulsion, deploying an explosive drive means sending up two propulsion systems rather then just putting more fuel into the first.

Two massive hurdles prevent the use of nuclear reactors in space, weight and the ability to operate them safely from remote. First, nuclear reactors are very very heavy with all that radiation shielding. Secondly we can not guarantee that remote systems will operate, it's hard enough to keep a well maintained reactor on the ground operating without constant human intervention (which is why they have constant human intervention) let alone one that will be completely unmaintained and far far from any human help. Solve these hurdles and the political one is trivial.

Hero (5, Insightful)

LoudMusic (199347) | more than 4 years ago | (#32261500)

NASA is my hero. They do cool shit all the time. Even when their stuff breaks, it's cool. Then they fix it and it's even more cool.

Re:Hero (1)

chichilalescu (1647065) | more than 4 years ago | (#32261592)

Well, you have to realize that there are only two classes of scientists that work on the edge: emergency room doctors and the people at NASA. Any other scientist can get back to the drawing board, and it's no big deal, but NASA people have only one chance at getting it right.
Offtopic: that's probably why real scientists are surprised that is such a thing as a "software bug" --- they don't really expect you to say a program works unless it actually works.

Re:Hero (1)

Thanshin (1188877) | more than 4 years ago | (#32261658)

that's probably why real scientists are surprised that is such a thing as a "software bug" --- they don't really expect you to say a program works unless it actually works.

Well, we could say the program works in theory, and then, when it doesn't, say it's all right, the theory was just disproven.

Or, we could say we don't know if works, but it's a good enough aproximation for what you need. And then we can put someone to investigate whether it really was.

Re:Hero (1, Interesting)

Anonymous Coward | more than 4 years ago | (#32261796)

Emergency room doctors are mechanics, not scientists.

They're paid to fix people, not find truth.

Re:Hero (1)

MichaelSmith (789609) | more than 4 years ago | (#32261810)

They do cool shit all the time.

No kidding [youtube.com]

Re:Hero (1, Insightful)

Anonymous Coward | more than 4 years ago | (#32262306)

NASA is my hero. They do cool shit all the time. Even when their stuff breaks, it's cool.

While the fireworks involved were indeed spectacular, I hear the crews of Challenger and Columbia would like to have a word with you for that bold statement...

Cosmic Ruse (2, Interesting)

XiaoMing (1574363) | more than 4 years ago | (#32261502)

First I was going to suggest that this satellite would careen forward out of control like a Toyota, but then realized that wouldn't be quite accurate.

The cosmic rays we get one Earth are actually short-lived particles such as muons (a fat electron, probably most well known aside from the standard protons-neutrons-electrons) that result from cosmic naked hydrogens hitting our atmosphere. Out in space though, it'd be interesting to see if those protons would have the same effect as a terrestrial "cosmic ray".

Unbelievable (2, Funny)

Arker (91948) | more than 4 years ago | (#32261682)

You telling me NASA doesnt even use parity memory? Seriously?

Just don't brick it! (2, Informative)

WGFCrafty (1062506) | more than 4 years ago | (#32261714)

The Voyagers are my favorite probes!

I wonder how many bits they'll have to send to change the one wrong one, and how long that will take.

Leave it to the stoner astrophysicists Carl Sagan to oversee one of the more amazing feats of space trave!!

Radioisotope thermoelectric generator [wikipedia.org] s are awesome!
Anyone know how much fuel is remaining? They've been heating up for knowledge for a long period of time.



Personally, I want about 6 of the units in Voyager 2, screw solar!

Ahh... (0)

Anonymous Coward | more than 4 years ago | (#32261736)

So that's NASAs way of saying they're going to turn it off, and turn it back on again.

NOTE TO NASA ENGINEERS: Remember, when the machine comes back up, spend 2 minutes flicking through the log files to give the investors the impression that you care. If you can't find any problems - casually inform them that you are going to "check things on your end, and that you will come back to them", before quickly and quietly slipping out of the room...

Disappointed (1)

euyis (1521257) | more than 4 years ago | (#32261784)

So it wasn't hijacked by some alien hackers...

This will ruin history... (1)

nielzz (822766) | more than 4 years ago | (#32261830)

... imagine the first Alien race we meet will be known as the 'bit-flippers'.

What, no ECC? (1)

nuckfuts (690967) | more than 4 years ago | (#32262070)

I'm surprised that a single-bit error is even an issue on such an important (and expensive) piece of equipment.

Hamming codes [wikipedia.org] have been around since the 1940's.

Re:What, no ECC? (2, Informative)

ledow (319597) | more than 4 years ago | (#32262346)

The spacecraft is in an incredibly hostile environment. Who's to say that there *wasn't* ECC and it's just that it's Hamming code wasn't enough to compensate for the error - it would make sense: as the hardware ages, the device leaves the solar system, the errors start getting closer and closer to the limits of error correction until one day - bam, even with error correction it slips through the net and ends up as a bad bit in memory.

Technically, this is possible (but incredibly rare) on even the greatest error correction in the world. Error correction is a statistical function, that says that the *chances* of an error occuring are 2^8, or 2^16 or whatever.

And, from my coding theory class, Voyager's signal was originally something ludicrous like a (24,12,8) code even when it was nearby. (This presentation, especially the final slide, appears to confirm that: http://www-math.cudenver.edu/~wcherowi/courses/m6409/mariner9talk.pdf [cudenver.edu] ).

ECC is a probability function - the probability of a bit error going undetected is significantly reduced compared to, say, just sending the data and hoping for the best. But reduced does not mean eliminated. Not all errors can be detected and only a small portion of those can be corrected. But that still leaves room for an error that goes uncorrected, undetected and ends up in RAM without anyone noticing until they do a full bit-by-bit check - the same as your 25+ years newer technology harddrive, Ethernet connection, computer bus, etc. There's no such thing as guaranteed data delivery - but we make the chances of an error slipping through so infinitesimally small that it doesn't affect normal, everyday operation. For instance, a corrupt download with an SHA-1 checksum would be seen as valid approximately one in every 2^160 transactions. Small, but not impossible by a long stretch considering how many downloads occur each day.

Voyager didn't have the luxury of Megabytes of RAM to hold extraneous checksum data, Megahertz of CPU to check everything that came in at line speed, or a broadcast technology that could keep a Gbit data rate going all the time. They made compromises and, later, changed the ECC algorithms as more and more errors could theoretically creep in. We just had a run of bad luck that meant a single bit was out, that's all. And that's even assuming it's not a hardware failure anyway. I think Voyager did pretty damn well, running for decades after it's supposed operational time. And a one-bit error on a random chance is pretty damn minor - let's just hope it wasn't inside anything too critical, like the communications routines.

Time Delay (1)

AceJohnny (253840) | more than 4 years ago | (#32262088)

NASA plans to reset Voyager's memory tomorrow

Considering the distances involved, I found it funny that the sentence implied simultaneity. Voyager 2 is about 92 AU out (according to WP), which is 12 light-hours and 45 light-minutes. So if they send the signal in the morning, the memory will be reset in the afternoon, and they can hope for clean signals the day after.

Voyager 2 source code... (1)

bagsta (1562275) | more than 4 years ago | (#32262202)

So, for that reason we couldn't find any alien...

#include <stdio.h>
#include <stdlib.h>

#define TRUE 0x00
#define FALSE 0x01

...
int sock_fd;
char line[50] = "Alien found!!";
int size = 15;

...

if (ALIEN_FOUND == TRUE)
send(sock_fd, line, size, 0);
else
continue;

...

butterflies in space ... (1, Informative)

dltaylor (7510) | more than 4 years ago | (#32262204)

So who misused the emacs macro?

For those of you who don't get the (obligatory) xkcd reference:

http://xkcd.com/378/ [xkcd.com]

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