Antique Voyager Technology 293
sea_stuart writes with a story from the Tidbinbilla space tracking station, outside Canberra, Australia. It is still communicating with the two Voyager spacecraft 30 years after they were launched and 18 years after Voyager 2 passed close by Neptune. Here's a little background on Voyager 1 and Voyager 2. "The bank of computers that would look at home in black-and-white episodes of Doctor Who cannot be junked... [T]he 1970s hardware is now our world's only means of chatting with two robot pioneers exploring the solar system's outer limits. Today Voyager 1 is humanity's most remote object, 15.5 billion kilometers from the sun. Voyager 2 is 12.5 billion kilometers from it. Both continue beaming home reports, but now they are space-age antiques. 'The Voyager technology is so outmoded,' said Tidbinbilla's spokesman, Glen Nagle, 'we have had to maintain heritage equipment to talk to them.'"
I've got an old dell they can use... (Score:5, Insightful)
I can still play my atari 2600 games on my xbox.
Re:I've got an old dell they can use... (Score:4, Insightful)
Re:I've got an old dell they can use... (Score:4, Insightful)
That said, I think the real reason isn't that it's not possible to duplicate with modern technology (it is, of course; anything we could have built then, we can build now), it's just that producing a new system just to communicate with Voyager would probably cost more than maintaining what we've got now. Especially since any new system would likely have unforeseen bugs in it, which could possibly result in loss of communication with the space craft (imagine accidentally sending a command which orders the Voyagers to point their radio antennas away from Earth).
Still, it's a bit like the ridiculous argument that some day we won't be able to read CD-ROMs, because the technology will have advanced so far, the hardware will no longer exist. Well, yes, maybe. But scientists will always be able to build something that can scan the surface of a CD-ROM, and decode the data there. But it might not be very economical (though I doubt it; a binary infrared laser scanning device is pretty dirt simple). There's a big difference there between what's economically and technologically unfeasible.
Cost benefit analysis (Score:3, Insightful)
Its probably the different pots of money question. (Score:2, Insightful)
Re:What about this requires old equipment? (Score:4, Insightful)
it's cheaper, this way. (Score:1, Insightful)
i think it's safer and cheaper to leave it alive...
for younger folks thinking about emulating it on an off the shelf machine: current architectures and hardware are not always "better"; space exploration aside, for certain goals it's simpler to use a '70 thing working a custom tailored board than a oh-shi...-look-at-that-latency-its-impredictable!
6502s and z80s are still manifactured, indeed.
The original equipment probabily just works... (Score:5, Insightful)
Proof that it's not a problem to receive and decode. Transmit can't be any harder. But why "upgrade" it if they don't have to? The old equipment probably works just fine, so there is no incentive.
Re:I've got an old dell they can use... (Score:5, Insightful)
If you have to design both the hardware and the software, it's going to be expensive. Not to say untested. And with the probes being where they are, it's not like you get a second chance if there's a bug. Things have to work perfectly, every time. You'd have a hard time convincing anyone that your emulation would be perfect enough to replace something that's aced the test of time for 25 years.
Re:I've got an old dell they can use... (Score:5, Insightful)
They do. First, take a look at
http://voyager.jpl.nasa.gov/mission/weekly-report
Namely (of the latest one):
Voyager 1 command operations consisted of the uplink of a command loss timer reset on 08/04 [DOY 216/0135z] and CCSL A064 on 08/06 [DOY 218/0236z]. The spacecraft received all commands sent and the CCSL was verified.
Voyager 2 command operations consisted of the uplink of a TLMPRG and a command loss timer reset on 08/06 [DOY 218/1329z]. The spacecraft received all commands sent and the Telemetry Purge proceeded nominally per predicts.
So yeah, they are still uplinking stuff - mostly just command loss timer resets.
What happens if they don't send the timer reset? Well, see
http://voyager.jpl.nasa.gov/science/thirty.html [nasa.gov]
If the timer reaches zero, as a result of a command not being received by the spacecraft within the programmed six week duration, the command loss timer will have expired and the Command Loss (CMDLOS) routine will be activated which leads to the initiation of the BML.
The implementation of BML-7 (the seventh BML to be loaded on-board Voyager 2), in conjunction with the baseline sequence, provides this automated protection against loss of command capability. BML-7, with some differences in implementation for the two spacecraft, is loaded on-board both Voyager 1 and 2.
So yeah, if receiver on V-ger gets broken, or the transmitter down here on earth, the ship can continue to still send data down here in a completely autonomous fashion. However, a remote capability is probably a good idea to have if something interesting comes up.
(The link has more details what the "BML" entails).
Re:Cost benefit analysis (Score:3, Insightful)
(The definition of legacy is "something that works".)
Re:I've got an old dell they can use... (Score:5, Insightful)
An existing system that works has gone through the bowels of this system and been sanctified.
It would take as much money to re-engineer it as it does to maintain it. It is an annoying fact that getting money to fix something in either the military or government is easier than getting something new even if the new item would save money. This is one of the reasons several of the systems I've worked on were 20+ years old. The anti-mortar Firefinder radar being used in Iraq was designed in the seventies and finally approved and deployed in the 80s and is still in use today.
There are plans to replace it but right this instant they need them in the field so it costs much more to refurbish one than to buy either a 'newly' made one which is intended for foreign sales and is not authorized for procurement or procure the newest model.
Currently the latest and greatest is rumbling around the guts of the system and some prototypes were fielded in 1998 so expect them to be finalized in 2008 and accepted later....
I wish I could point and say "graft and corruption" but it's fighting that which has led to our current procurement system. It's not ever going to be perfect but it does help to keep sawdust out of MREs.
Re:I've got an old dell they can use... (Score:2, Insightful)
(a) they have the source code
(b) the source code is not too obfuscated from 1970s engineering paradigms that it can be understood
(c) the guy who originally wrote the system is not dead so that they can talk to him about all the eccentricities of it
(d) that it isn't too bulky to cause a slowdown on NASA's emulators when dealing with real time communication
(e) there is no funky encryption built into the system to protect it from the Soviets
In terms of cost/benefit analysis, it's probably just cheaper for them to leave the old equipment running than pay millions for consultants to take a look at how to port a 1970s communication system built at the height of the Cold War
Re:What about this requires old equipment? (Score:4, Insightful)
Failing that, you'd put the software under the DMCA and claim that it was the hd-dvd encryption algorithm. You'd have three different OSS solutions in a week.
They have the source code and the architecture (Score:4, Insightful)
I think these guys know what they are doing and if they choose to keep the old equipment running in order to communicate more relyably with the Voyagers, I trust they have perfectly valid reasons for it. And no, an off-the-shelf Dell is most probably not a feasable replacement. No matter how powerfull it is.
Oh, and by the way: A modern computer would drain voyagers batteries so fast, they'd be dead in a few hours. My old Sharp 1403 H Pocket Computer, built with technology from the early-to-mid 80s runs 200+ hours under full load on a pair of button-cells. I haven't replaced them in 10 years and it still runs on them. I have yet to find a modern handheld computer that can do this.
Re:I've got an old dell they can use... (Score:4, Insightful)
Give me a week and a modern microcontroller and I'll build you one. Someone else can write the driver.
outmoded? (Score:3, Insightful)
The voyager sats are some of our most successful missions, i'd challenge anyone to do better then their "out modded" systems.
Re:What about this requires old equipment? (Score:3, Insightful)
Re:I've got an old dell they can use... (Score:3, Insightful)
And there's the #1 reason not to touch this system already. Both probes have left the solar system and entered interstellar space. There's something like ~70000 years to the next star system. We're not expecting them to find anything, and if they did the direction they're going is probably as good as any. Right now it's just the record for "most distant object we've held communication with", so don't mess with it. Is it seriously that big a problem to keep the system going here on earth when you manage to keep it going in outer space? Ir's not like we need to upgrade it for any reason, it's basicly living its own life together with the Voyager probes, like a small bubble of the 70s. Worst case the hardware completely breaks down with no spares and we have to just listen to it, which is what we do already (I assume we can do that with more modern equipment). So where's the upside of moving to a newer system?
"Why can't they just" (Score:4, Insightful)
When someone says "Why don't we just", they're probably working on the project and know what they're talking about.
If they could just, they probably would have justed a long time ago. These are, after all, the people who rebuilt the receiver scheduled to receive the Apollo 11 LEM and EVA transmissions in just 12 hours, after it caught fire 1 day into the mission. It was NASA's call not to use them due to the problem, but they could have done it because they know very well what they're doing and how to do it.
Re:I've got an old dell they can use... (Score:3, Insightful)
And since you seem to hik we cant create 'new', what happens when one of the old ones die and we cant repair it due to its age? At least if we have tried to replicate the functions with modern equipment we have a chance.
Cost is relative, in this case.
Re:I've got an old dell they can use... (Score:3, Insightful)
Re:I've got an old dell they can use... (Score:5, Insightful)
First, the heliopause / helioshock transition did not happen the way they thought it did. It was in a different place and had different characteristics. They may still run into that, including vibration and change "bell ringing" of it. And, these things might be the only chance we EVER get to study the interstellar medium directly.
Second, there are light speed, distances vs. gravitiy issues where the spacecraft are NOT WHERE WE EXPECT THEM TO BE based on the equations we have to calculate for that. In other words, basic, fundamental cosmological questions can be pondered using these things.
The shame is, that people have been trying to turn them off thinking "we're done" when the cost to operate is a freaking drop in the bucket compared to the colossal waste that is the space shuttle. Put down your trashy science fiction novels for once and read some real papers produced by real science. Then you can get outside your narrow view of what one can "find" out there.
Re:They have the source code and the architecture (Score:5, Insightful)
Most people here are talking about upgrading the base station on Earth, not the spacecrafts. As someone else pointed out, most of the reason they are sticking with the old system must be quirky analog/RF components, not the bitstreams themselves - the Voyager base-station antenna is a huge dish array that recovers sub-yoctowatt signals from the probes. The analog/RF front-end needed to filter and amplify this signal before it can be decoded by digital equipment must be a very unique piece of analog kit with decades worth of tweaking and refinement poured into it both before and after the launch.
The digital decoding should be trivial with modern CPUs but the analog parts were most likely tuned to the point of defying modern technology.
Re:I've got an old dell they can use... (Score:3, Insightful)
They *already* built the system. They already have a staff capable of maintaining it and fixing it when it breaks. Building a new one won't let them communicate with the probes any faster.
So what would be the purpose of building a completely new one?
It blows my mind that nobody seems to understand upgrading "just because" is a really stupid idea.
Re:I've got an old dell they can use... (Score:4, Insightful)
Re:They have the source code and the architecture (Score:3, Insightful)
Granted, we still have some amazing engineers, the two rovers on mars are proof of that.
I think the funny part is that most people do not realize how incredibly big that voyagers are. 733Kg is HUGE for a space probe. The thing is nearly the size of a City BUS, and it actually has 420Watts of power from it's power source giving it an incredible amount of electrical power on board. the things were massive, but back then a basic computer with less processing power than my watch took up a toolbox, so it makes sense.
honestly I am sad that they havent done any follow up deep space probes with an ion engine to get them going on insanely fast (compared to the other probes) trip on out. it would be cool to see a photo of Pluto or some oort cloud objects.
Re:I've got an old dell they can use... (Score:3, Insightful)
Isn't that always the case? Yes, the system could be rewritten, if there was time and money to do so. Yes, the old hardware could be emulated, as-is, in new hardware. But the old hardware's bugs are known, are understood, and may even have become part of the de facto specification.
Under the circumstances, I'd nurse the old hardware along too.
...laura