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NASA Finds Cause of Voyager 2 Glitch
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."
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.
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)
Stupidity... has a habit of getting its way.
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 Apparently, there was some debate at the time over whether these new-fangled memories would be reliable.
1977 - when advanced microchips were not as powerful as the chip driving the shatty calculator you buy today at the dollar store.
Classic, ever repeated confusion of what "power" is. Unless you mean volts times amps, power is what you can do with it. An old mainframe can run a department of a small multinational corporation, maybe a large university, or perhaps a division of state government. We know this, because they did in fact do so, very profitably. You claim a dollar store calculator is more powerful. That means a dollar store calculator should be able to run, say, an entire multinational corporation, maybe multiple universities, or an entire state government. Oh wait, a dollar store calculator can, at best, slowly calculate someone's income tax, possibly correctly. I guess the old mainframe is more powerful after all.
When I worked at a mainframe shop in the late 90s I heard alot of similar tiresome comments... "Ha ha, mainframes, bet you didn't know my laptop can run NOPs faster than your mainframe can run floating point FFTs ha ha ha mainframes". At which point you simply tell them to put up or shut up, hand them a bus and tag cable, and have their infinitely "more powerful" laptop process 5% of the NYSE volume like our mainframes did, while supporting about 100K trader desks, a couple TB of tape robot storage, etc.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
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.
Oh no! What a terrible thing! There's nothing like that in space at the moment, how could we possibly manage?
The Van Allen belts contain high enough concentrations of radiation that they make Chernobyl's fallout look like spilt milk. The sun regularly pumps out solar flares that would kill unshielded humans in seconds. Compared to that, I find it very very difficult to be at all concerned by a tiny spacecraft literally billions of kilometres away.
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.
Oh dear, where do I start? Firstly, no, nuclear explosives (they're only bombs if you're dropping them on someone) are not necessarily "very heavy". They can be easily built small and light enough to fit into an artillery shell; if a serious Orion development programme was resumed, you'd be looking at 5-10 kg per charge, possibly less. In the Orion model, the pusher plate and damping structure are by far the most massive components. Secondly, nuclear explosions behave very differently in a vacuum than in air; most of the destructive power of a nuclear detonation on Earth is due to the way that the massive energy release affects the atmosphere. Thirdly, it's bloody hard to get a nuclear explosive to detonate. They can only detonate successfully if a very long and complex chain of events occur in precisely the right way. I think you overestimate the risk massively. Honestly, mining with conventional explosives is far more risky than propulsion using nuclear explosives will ever be. Finally, one of the biggest advantages of the proposed Orion propulsion system is that the mass efficiency is very high, meaning that it's possible to continue thrusting for a long period of time, so the whole point is that you want to use it "out in space."
I recommend reading 'Project Orion' by George Dyson if you want to know more about the practicalities of the Orion propulsion system.
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.
Which you don't need in space; you design the reactor so the majority of the radiation produced is directed away from the spacecraft. Look up NASA's SP-100 design.
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.
No, modern reactors run on almost completely automated systems, even down to choosing which rods should optimally be replaced next. Human intervention is only required when modifying output to match grid loads (and even then, that's largely automated too). Even if something goes wrong, modern reactor safety systems have so much redundancy and fail-safe assumptions
Pirate Party UK
Exactly. The IBM 360 had a truly incredible I/O capacity, powered by multiple parallel processing elements called "channels." You programmed them with "channel command words" or CCWs. They were independent of the main CPU. When a channel needed memory, it got locked down (pfixed) and allocated to the channel, so the channel could piss into memory at high speed. Really large, thick cables connected the CPU with peripheral devices. These cables had lots of wires in them. Because lots of bits were flowing IN PARALLEL. Look up the transfer rate of a 2701 drum drive, still maintained and used for paging devices as late as the 1980's by companies who could not find anything faster.
When DEC tried to claim that they could replace 360's with VAX's, guess what happened? They didn't have massively parallel I/O processors. They didn't have a massive transfer capability. They generated an interrupt on every character typed by every user, for God's sake. They were not I/O engines. They failed, utterly. Not that VAX wasn't a good machine, but no way could it replace a 360.
How did a small 360 support hundreds of users? Why, through an innovation called "CICS." What happened was, the mainframe would fill a 3270 CRT terminal screen with a "form." You would fill in the form, locally, using the "smart" 3270's field-editing and checking capability, with no interaction with the mainframe. When you were finished filling in your form, you'd hit TRANSMIT. At which point, the variable data on your form would be glued together by the 3270 in one record and sent up for processing by the mainframe (along with everyone else's form data). A few seconds later, you'd get another form in response. Lather, rinse, repeat.
Oh wait. That's exactly how most business Web applications work. Except the screens are prettier.