# Voyager 1 fires thrusters last used in 1980 – and they worked!

NASA's announced that Voyager 1's already-amazingly-long mission will probably be extended for an extra two or three years, thanks to a successful attempt to use thrusters that haven't fired up since the year 1980. As NASA announced last Friday, Voyager 1's been using its “attitude control thrusters” (ACMs) for decades, to …

1. #### it's already doing 17.46 km/hour

That doesn't sound right.

Better.

1. #### Re: it's already doing 17.46 km/hour

When you're going that fast, doesn't time slow down or something. Resistivity I expect.

1. #### Re: it's already doing 17.46 km/hour

"doesn't time slow down or something"

Well, technically yes, but by such a tiny amount you would be hard pressed to measure it. You would need to be going a respectable chunk of C to get any noticeable effect.

1. #### Re: time dilation

You would need to be going a respectable chunk of C to get any noticeable effect.

However, even a small chunk of Java will slow your computer to a crawl.

2. #### Re: it's already doing 17.46 km/hour

@Geniality "You need to be going very close to the speed of light (299,762 km/sec) for time dilation to become meaningful on a macroscopic scale. "

Tell that to the GPS satellite physicists. They'll set you straight^H^H^H^H^H^H freefall trajectory through curved spacetime.

http://physicscentral.com/explore/writers/will.cfm

1. #### Re: it's already doing 17.46 km/hour

Clocks on GPS sats run faster than their Earth bound counterparts because they are higher up out of Earth's gravity well. That speeds those clocks up much more than the velocity of the GPS sats slows the clocks down (which is negligible).

1. #### Re: it's already doing 17.46 km/hour

GPS has correction for both gravity (general relativity) and velocity (special relativity). Both are needed.

2. #### Re: it's already doing 17.46 km/hour

@Barley registers Satellites have to keep incredibly precise time, down to the picosecond (which isn't macroscopic). Voyager 1 doesn't. As I said, time dilation takes place at any relative velocity but it takes a long time to build up to something meaningful. Even for GPS satellites it takes months to go a few picoseconds out of sync with Earth-based stations.

1. #### Re: it's already doing 17.46 km/hour

Money quote: "But at 38 microseconds per day, the relativistic offset in the rates of the satellite clocks is so large that, if left uncompensated, it would cause navigational errors that accumulate faster than 10 km per day!"

So - relativistically tiny speeds still causing 10km per day error.

Pretty meaningful in my book. Your mileage may vary. (Ha! see what I did there?)

3. #### Re: it's already doing 17.46 km/hour

"You would need to be going a respectable chunk of C to get any noticeable effect."

But you'd almost certainly be having the time of your life, and wouldn't much care either way.

2. #### Re: it's already doing 17.46 km/hour

You need to be going very close to the speed of light (299,762 km/sec) for time dilation to become meaningful on a macroscopic scale. It does happen at any speed though, Voyager's time travel relative to Earth would be a bit less than 2 seconds, accumulated over the last 40 years, if it travelled in empty space. Because of its tour of the outer planets, their gravitational wells actually sped up its relative time. It's hard to calculate how much dilation that caused though, since it depends on altitude and how many bodies (planets, moons and rings) had a meaningful impact.

3. #### Re: it's already doing 17.46 km/hour

'When you're going that fast, doesn't time slow down or something. '

Which explains why the records were 45rpm on one side and 33 1/3 on the other.

1. #### Re: it's already doing nnn,nnn KM/sec !

Well perhaps back in 1980 it was a cylinder and not a golden disk originally.

As Voyager approaches the speed of light, something called the Fitzgerald contraction becomes effective.

There once was a fencer named Fisk,

Whose speed was incredibly brisk.

So fast was his action,

The Fitzgerald contraction,

Foreshortended his foil to a disk.

4. #### Re: it's already doing 17.46 km/hour

17.46 km/s is not close enough to light speed for significant time dilation, but the fact that Voyager is so much further out of the Sun's gravity well, the on board clocks of Voyager would certainly be ticking faster than clocks on Earth. Gravitational time dilation even has to be accounted for on GPS satellites and they're much closer to Earth (and the Sun).

5. #### Re: it's already doing 17.46 km/hour

"When you're going that fast, doesn't time slow down or something"

yes but the amount is negliglble. you'd probably notice if you're receiving radio signals that are supposed to be xx.xxxx Mhz, but end up being xx.xxxy Mhz [that kind of difference].

As I recall, on one of the Apollo missions, they had an atomic clock or something similar on board the spacecraft, and they actually measured the time difference. Since they were moving at ~50k MPH for the trip to/from the moon, there would be a measurable effect, even though it was pretty tiny. But, the scientists involved in the experiment DID find "that difference" and announced that Einstein WAS right. It was definitely worth doing, yeah.

You can figure out the effect on time when you consider that if you're travellng at 1/2C, then [simplified] from YOUR perspective, light still moves at C, which means that for you, time effectively moves 1/2 as fast as it is for someone who's not moving at all. It's actually more complicated than that, but discussing all of the details in here would be TLDR and *yawn*. NOT mentioning that would invite the anal retentive howler monkey types to nit-pick every word.

anyway, ~18km/sec compared to ~300,000 km/sec is a pretty small change in the flow of time, but it's in the neighborhood of 1/10,000 [unless I made a math error] so radio frequencies would be shifted in a measurable way [as I already mentioned at the top] but that's about it. What's interesting, however, is that the shift would probably be TWICE what doppler alone would cause, because the relative time would affect the RF oscillators, which would put out a lower transmit frequency, which would then be further time-stretched by the doppler effect as the craft moves away from earth.

[gravity wells, as mentioned earlier, notwithstanding]

6. #### Re: it's already doing 17.46 km/hour

17.46kps really isn't that fast when compared to light speed at 300,000kps, so any time dilation can safely be ignored. The dilation only becomes meaningful when you get up to higher fractions of light speed.

According to Relativity time will slow down even when you just walk to the corner store. Its all about how fast your moving relative to another point of reference.

2. #### Re: it's already doing 17.46 km/hour

From JPL site:

Voyager 1 present speed relative to Sol

38 026.77 mph = 16.999 km/s (in Standard International units)

So a small units error on the reporter part.

1. #### Re: it's already doing 17.46 km/hour

> "A small units error"

Sure, just like the Mars Climate Orbiter in 1999 had a small units error! No biggy!

1. #### Re: it's already doing 17.46 km/hour

I imagine the Reg reporter made a slight error working with such unfamiliar units. If we could all just start using the Reg Standard Units, ff/f, there would be no such confusion (football fields per fortnight).

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3. #### Re: it's already doing 17.46 km/hour

Luckily just missed the YR2000 bug, tho!

2. #### "16.999 km/s (in Standard International units)"

That's about Mach 49 (for reference Earth orbital velocity is about M23).

OTOH that's 0.0056% of the speed of light.

However in principal systems can be engineered (no breakthroughs in physics, including fusion, needed) that could get to 5% of the speed of light.

1. #### Re: That's about Mach 49

Mach number is relative to local speed of sound so a velocity doesn't correspond to any specific Mach number unless you know what the local speed of sound is. For ideal gas the local speed of sound is a function of temperature (and temperature only). As for the temperature of the so-close-to-vacuum-as-makes-no-difference environment of the Voyager probes (assuming analyzing it as ideal gas even makes sense)... I have no idea.

3. #### Re: it's already doing 17.46 km/hour

Maybe 17.46 thousand miles/hour?

Metre and Mile have the same symbol.

M and m

1. #### Re: it's already doing 17.46 km/hour

I saw somebody at the weekend wearing a leather biker jacker with "1000m/h" proudly embroidered onto it. I decided against informing him that I could walk faster than that.

1. #### Re: it's already doing 17.46 km/hour

Possibly why us runners tend to use minutes per mile or for the modern inclined minutes per km. I having grown up in metric NZ and being an SI unit using scientist (I have to think about what an Angstrom is) for some reason which is opaque to me still use minutes per mile. Though for a rough and ready 5min/km = 8min/mile.

I suspect it is because most road distance races are 5miles, 10miles, half marathon (13.1miles) or marathon (26.2miles) etc. 10km's (6.25miles) is an aberration in the system. I bow to the track system of course though I haven't run a track race in several decades. Cross country races tend to be approximate due to the nature of the beast, proper cross country races anyway, with sucking mud patches and fences you have to vault with cow pat hazards. Sheep droppings are a mere inconvenience.

1. #### Re: it's already doing 17.46 km/hour

The only official IAAF run which is measured in miles is the 1 mile race - that's the aberration. A marathon is 42.195km - metric! Or White City Stadium to Windsor if you prefer.

2. #### Re: it's already doing 17.46 km/hour

Metre is m, mile is M. Most uk motorway signs are definitively incorrect

1. #### Re: it's already doing 17.46 km/hour

Metre is m, mile is M. Most uk motorway signs are definitively incorrect

No, you are incorrect as mile is m, a unit is only a capital letter if it was named after a real person K - Kelvin. T - Tesla etc.

1. #### Re: it's already doing 17.46 km/hour

So there is a Mr. Byte?

IEEE 1541

bit = b

byte = B

4. #### Re: it's already doing 17.46 km/hour

In the last thirty seven years, Voyager 1 has 'lost' almost two whole seconds, compared to us on the earth due to relativistic velocity time dilation.

(not really 'lost time', more, 'experienced time at a rate very slightly slower than us')

(On the other hand, being in a smaller gravitational field, the Voyager probes will have 'gained' some time as well, but less than lost to velocity)

5. #### Re: it's already doing 17.46 km/hour

@Steve Button

Give Voyager a break. It's 40 years old and maybe it's going up a hill!

1. #### Re: it's already doing 17.46 km/hour

'maybe it's going up a hill!"

Well it is actually - going up a 'gravity hill', aka, escaping from the suns gravity well.

2. #### 17.46km/HOUR???

Shome mishtake, surely?

I can RUN that fast.

I can't.

2. #### Re: 17.46km/HOUR???

I can RUN that fast

Not in deep space you can't.

1. #### Re: 17.46km/HOUR???

In space, no-one can see you run...

1. #### Re: 17.46km/HOUR???

But they can hear over the radio if you have the runs.

1. #### Re: 17.46km/HOUR???

Having the runs in a spacesuit must be a whole new level of horror.

1. #### Re: 17.46km/HOUR???

Even worse if you’re spinning too.

2. #### Re: 17.46km/HOUR???

But they can hear over the radio if you have the runs.

1. #### Re: Apollo 8

"He vomited twice and had a bout of diarrhea; this left the spacecraft full of small globules of vomit and feces"

OMG!

2. #### Re: 17.46km/HOUR???

"In space, no-one can see you run..."

or hear you scream

1. #### Re: 17.46km/HOUR???

or hear you scream

"I Scream, You Scream, We All Scream for Ice Cream"

3. #### Re: 17.46km/HOUR???

>I can RUN that fast.

While we can manage this top speed for a short time, it is quite hard for an hour:

My record is 12.85km in an hour, the world record is 21,25km/hour

https://en.wikipedia.org/wiki/One_hour_run

3. Joke will be on us if a salvage scow finds Voyager, and recycles it just for the gold it carries.

1. recycles it just for the gold it carries.

Hmmmmm ? what makes you think a civilization that has the tech to hop to solar systems needs to intercept a flying object for mere ounces of gold ... they could easily reach planets with megatons of the stuff ?

1. According to a TV drama/documentary that I once saw, something very special will happen to Voyager.

1. This post has been deleted by its author

1. @Frank. Are you sure that film wasn't about Voyager 6?

No, it's from Martian Chronicles.

2. "they could easily reach planets with megatons of the stuff" (re: recycling v-ger for its gold)

right, heavy elements (like gold) are quite possibly more common on inner planets, and if you mine stuff at night, and at the poles, not unreasonably hot either. If I had the tech available, I'd certainly give it a shot.

the basic logic: outer planets are nearly all 'gas giants', inner ones are rocky. It seems to me that heavier elements collect closer to a star than farther away from it. Conclusion: Mercury probably has more gold than Earth.

asteroid mining would give you easier physical access to "everything", too, but how much gold, platinum, and other 'rare earths' being present in asteroids is still completely unknown.

Anyway...

1. #### how much gold, platinum ... present in asteroids is still completely unknown

True, but all the platinum group metals mined in southern Africa are found in the remnants of two large meteor strikes which hit the planet after the crust was formed. Any gold, platinum, etc... present at the formation of the planet would have settled to the core before any crust formation.

1. #### Re: how much gold, platinum ... present in asteroids is still completely unknown

Scroticus Canis, precisely the reason Mercury might be a good place to prospect if energy to change orbits was cheap enough. It seems to have lost its crust and maybe mantle due to the energy of impacts. NASA did well with Messenger.

On another suggestion, NASA have chosen an apparently metallic asteroid which may be a core remnant for a mission. Current energy technology makes space mining hopelessly uneconomic for the foreseeable future unless fusion reactors can use He3. Then it might be worth mining the Moon for helium, not metals.

2. "Joke will be on us if a salvage scow finds Voyager, and recycles it just for the gold it carries."

We'll have the last laugh though, the record is only gold-plated copper.

3. The late Mr Waldheim vill not be pleased.

4. #### how is assembler outdated and by what?

"Chris Jones said “The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters."

Have they done a Intel and changed the mnemonics for some reason? or were they expecting to find the CPU had been upgraded in the meantime

Why don't they just say the assembler was not what their programmers were used to but the process of getting back to fundamentals was a rewarding challenge for them.

1. #### Re: how is assembler outdated and by what?

Assembler is not outdated - its just reserved for special people. The look on a childs face when you step through an assembler program in a simulator so they can see the data move around the CPU is only for special people.

1. #### Re: how is assembler outdated and by what?

/That particular/ assembler (or rather, instruction set) is outdated. It's not like there's a Pentium in there.

2. #### Re: how is assembler outdated and by what?

Or old farts (like me) who were weened on assembler - OS, compilers, utilities, large multi-tasking systems, EVERYTHING in assembler!

2. #### Re: how is assembler outdated and by what?

Assembler is CPU specific and this particular CPU is decades old. So this particular Assembler language IS outdated.

1. #### Re: how is assembler outdated and by what?

"this particular Assembler language IS outdated."

Not if there's a functioning CPU to run it on.

1. #### Re: how is assembler outdated and by what?

As far as I remember, it uses a bit-slice CPU (not any Intel rubbish), so the architecture is custom-made, implying a proprietary instruction set.

2. #### Re: how is assembler outdated and by what?

The language is only outdated if it's been replaced by newer ones.

It's not like someone can nip out there and update the hardware. So for the CPU on Voyager 1, this assembler language is the latest and only language. It therefore cannot be outdated.

3. #### Re: how is assembler outdated and by what?

Outdated?

The 8086 popped up in the late 1970s and, albeit with endless "improvements", the assembler is still with us.

That seems to be quite old, but not outdated given that the architecture is still with us.

3. #### Re: how is assembler outdated and by what?

AFAIK, the Voyagers use old CPUs designs and thereby the related assembly code could look quite outdated compared to today standards - and probably the toolset to work with as well.

There's no a single "assembler", each assembly language is strictly tied to the CPU architecture it is designed for (being, after all, just a human representation of CPU opcodes), and they can be quite different from each other, although some basic instructions may be quite similar. If you learned assembly on an x86 today, and one day try to program a 6502, you'll find it outdated, and you'll have to learn not only the mnemonics, but how they need to be used on that particular architecture and hardware implementation.

And remember, they are not allowed a trial&error approach like most developers on Earth... sure, they can simulate, but once the instruction sequence is finalized, it has to work, and those old system have very few or none safety belts.

1. #### Re: how is assembler outdated and by what?

For some reason I am reminded of that old classic tune - RS232 Interface Lead.

My favourite lyrics being from the operatic version..

-Come here, my lovely Tosca, I have something that will forever solve your information transfer problems.

-Not so fast, Buster. I already have an R.S.232 Interface Lead, but it hasn't solved my local networking difficulties, so I'm going to kill myself.

1. #### Re: how is assembler outdated and by what?

@Sir Runcible Spoon

RS232...

I have something that will forever solve your information transfer problems.

Shirley, Kermit and his Protocol is the answer?

2. #### Re: how is assembler outdated and by what?

I once came across a frustrated RS232 user who proposed another control line - DTS, which allowed one to send at will and was called Determined To Send!

2. #### Re: how is assembler outdated and by what?

The PIC assembler is fairly ancient (over 40 years old?), esp for 16x84 family. The the 8-bit PIC was developed in 1975 by GI. The later 16C84 (1985?) used essentially same Assembler, A version of the 16F84 (software compatible) is still sold.

I did SC/MP and then Z80 in 1980 and Intel 8051 in 1983. Also the NEC7800 (really primitive), I wrote a Forth like environment using MacroAssembler for the NEC7800. It was a shock trying the 16F8x family in 2003. I soon changed to C and then JAL for my PIC projects.

Compiler tech has improved so much that you don't need assembler for microcontrollers now, except the odd inline instruction to do something to a register not efficient in the language.

" x86 today, and one day try to program a 6502" If you mean an x86 in actual 8086 mode, no. Even the 286 just adds instructions so you can have flat memory model. The 386 a few more for virtual memory etc, basically based on 8080, which is same era as 6502 and maybe not as nice. The Acorn ARM team designing the new RISC cpu started with the 6502 as a sort of template!

ARM is MUCH nicer than evil x86.

1. #### Re: how is assembler outdated and by what?

Interestingly, all of the CPUs you mention are too new too have affected Voyager design. I just viewed a documentary titled "The Farthest: Voyager in Space" that included comments from some of the engineers and scientists involved with the Voyager program. One of the engineers commented that in the interest of stability, technology was locked in as of 1972. The 8080 (1974) and 6502 (1975) were too new to have qualified. Voyager used 3 different designs, but the Attitude and Articulation Control Subsystem used an updated version of that used on the Viking spacecraft, a General Electric 18-bit TTL design with 64 instructions that used plated-wire RAM. It is rocket science, after all. They couldn't afford to trust a commercial CPU that was never tested in a high radiation environment.

1. #### Re: how is assembler outdated and by what?

What! ?? Don't go! Wait! Wait! I was going to make Espresso!

I mean I was going to program it in Fortran. Or at least Basic!

3. #### Re: how is assembler outdated and by what?

What tool set? In those days we assembled the code by hand and entered the hex code into an EPROM programmer directly.

4. #### Re: how is assembler outdated and by what?

By outdated assembler language im going to assume they meant it uses AT&T syntax and confused them with everything being the wrong way round.

5. #### Re: how is assembler outdated and by what?

I've read that the CPU in question was a RCA 1802. Can anyone verify that?

1. #### Re: how is assembler outdated and by what?

General Electric provided the CPU for Voyager, as they had for the earlier Viking system http://www.cpushack.com/space-craft-cpu.html

The RCA 1802 was launched barely a year before Voyager, so could never have been used. It did see use in NASA in the Magellan and Hubble projects over a decade later, which gives you an idea of how long these projects take to design and launch.

The CPUs in Voyager were 18-bit machines with 64 instructions. They seemed to be a one-off custom job for NASA, as GE never commercially offered a CPU, nor did any other GE minicomputer had such an odd word-length (although its 600-series was 36-bit). This would definitely confirm the "obsolete assembly language" part of the story.

6. #### Re: how is assembler outdated and by what?

Have they done a Intel and changed the mnemonics for some reason? or were they expecting to find the CPU had been upgraded in the meantime

Why don't they just say the assembler was not what their programmers were used to but the process of getting back to fundamentals was a rewarding challenge for them.

There is a awful lot to a complete assembly language than the bare instruction set: red tape directives, psuedoinstructions, how variables are referenced (and possibly typed), macros, even fundamentals such as comments and default (or even acceptable) bases.

None of these affect the CPU in the slightest but make a big difference to how assembly programming feels. Older niche architectures typically had very bare bones assemblers. Nowadays even an experimental research architecture can easily have a full featured assembler in a couple of hours using a assembler development kit, so yes I certainly recognise the outdated label.

5. "The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters."

I expect they had useful comments and documentation too, which will never be outdated. In fact many companies haven't even heard of them yet.

1. My first computer in 1979 had a Z80, like an 8080 on sugar (steroids as a meme had not been invented yet). So, STOSB ? But I'm guessing that NASA preferred military-grade cosmic-ray hardened.... if the manufacturer was neither Intel nor Zilog but something like Fairchild, I wouldn't be surprised.

1. http://www.cpushack.com/space-craft-cpu.html

There are three CPUs on each Voyager spacecraft. Two of the CPUs were made from TTL logic, including the attitude and articulation control subsystem. One of those was a copy of the Viking lander CPU, and the other was an enhanced version of it. The third CPU was a custom CMOS design.

1. Thought that the CPU was a radiation-hardened COSMAC 1802.

Phil.

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1. #### Re: CDP1802

"...Hedy Lamarr didn't really invent Spread spectrum..."

She invented band-hopping radar, and even applied for a patent, but the hardware of the time was too clumsy to implement it.

6. "it's already doing 17.46 km/hour"

No faster than me on a bike then?

No wonder we can still communicate with it!

1. Yes you can communicate with it if you have the patience to wait 39 hours for an answer

1. A bit like the IT support desk when you tell them the customer facing servers are inaccessible.

2. >Yes you can communicate with it if you have the patience to wait 39 hours for an answer

Good thing SatNat didn't exist back then...

7. #### Not used since 1980

I wish more of the stuff we have to buy today could still be relied on to work in 30 years time. Surface, anyone?

1. #### Re: Not used since 1980

My MK14 from ~1980 still works. Never quite got round to fitting it with thrusters or it most certainly wouldnt.

1. #### Re: Not used since 1980

"My MK14 from ~1980 still works. Never quite got round to fitting it with thrusters or it most certainly wouldnt."

Now that is an obsolete assembly language machine code. Well I hope it is obsolete. I used to write for it with a typewriter !

And, yes, I've also still got one

1. #### Re: Not used since 1980

Re chemist - you can write for the MK14 in assembler now! There is a table for TASM somewhere - and there's even a smallC compiler for it.

8. #### Intercepting Voyager?

Let's be honest, if Voyager is ever intercepted by another spacecraft then that other craft is likely to contain... us! We know where it is, and the chances of anyone/anything else out there bumping into it must be tiny. Surely the chances are that we'll go and hunt it down for posterity once we've sussed proper interstellar travel?

(Aside from that: the sheer thought that the Voyagers still work, and are so far away, just boggles the mind. I can't comprehend either the distance or the coolness of the humans that made them and keep them going. Outstanding.).

1. #### Re: Intercepting Voyager?

"Surely the chances are that we'll go and hunt it down for posterity once we've sussed proper interstellar travel?"

I can see it now. Hanging from the ceiling of the Smithsonian [Dubai Edition].

2. #### Re: Intercepting Voyager?

"Surely the chances are that we'll go and hunt it down for posterity once we've sussed proper interstellar travel?"

And tonight on Antiques Roadshow we have Brian, who found something interesting passing through the Smaller Magellanic Cloud.

[ You do know that Antiques Roadshow will outlive Voyager? ]

9. #### Space is good for you sometimes

Just imagine: After 37 years, the seals on those thruster valves still opened without damage, and held tight again. Wouldn't want to rely on that with a faucet that hadn't been used since 1980.

Just shows what you can do when there's no stupid oxygen or light around.

1. #### Re: Space is good for you sometimes

Yeah, but it's only 19 light-hours away.

1. #### Re: 19?

Wow. Just wow. So return signals/responses take about 2 days? I know relativity. I understand the principles. I'm fine with what ever bizarre reality is thrown at us (relativity and different reference frames from GR, QM giving interesting principles in possible outcomes and effects at a distance)... but I'm still boggled and amazed at the practical and real effect it has!

Beer, because that can also give you a looooong delay on getting work done.

1. #### Re: 19?

Relativity has almost nothing to do with the fact that signals have a 38 hour there and back transit time. This time period is because the spacecraft is so far away, roughly 19 light-hours in distance, that radio signals take 19 hours to reach it and the reply takes 19 hours to return.

Technically the return time will, on average, be marginally longer than the out time but that's more because the spacecraft is slightly further away from Earth by then than any other effect. How much this matters compared to Earth's orbit is another matter. Earth's orbital speed is 30 km/s, roughly twice that of Voyager 1, this is in a roughly circular orbit therefore roughly half the time Earth's orbit will be increasing the distance and the other half it will be reducing the distance but there will only be short periods when the maximum relative differences in velocity come into play.

1. #### Re: Nick Ryan

Relativity has everything to do with the speed of light being a limit to communication times. Irrespective of the exact distance.

2. #### Re: 19?

Not true because for part of the solar year, we are gaining on voyager quicker than it is leaving us

2. #### Re: Space is good for you sometimes

"After 37 years, the seals on those thruster valves still opened without damage,"

Indeed, though I do wonder why they used attitude control thrusters which are dependant on a limited fuel supply in the first place instead of reaction wheels which simply require electricity.

1. #### Reaction wheels

Reaction wheels and gyros only work to alter the orientation of a spacecraft while they are spinning. Slow them down to a stop to save electricity and wear and tear on the bearing etc. and the spacecraft settles back into its original orientation. They don't last forever -- the Hubble space telescope has/had multiple redundant sets of reaction wheels used for tracking during observations and most of them have stopped working IIRC.

Expend some mass through a thruster, the spacecraft will rotate. Fire off some more mass in the opposite direction, it will stop rotating and stay in its new orientation.

1. #### Re: Reaction wheels

Hubbles Gyro's have been replaced twice.

2. #### Re: Reaction wheels

Reaction wheels and gyros only work to alter the orientation of a spacecraft while they are spinning. Slow them down to a stop to save electricity and wear and tear on the bearing etc. and the spacecraft settles back into its original orientation.

Reaction wheels will set a fixed orientation: assuming the probe is in a stable orientation spin up the wheels and the probe will begin rotating in response. Stop the wheels and that reaction is reversed stopping the rotation, in general in a new orientation.

What reaction wheels can't do in a sustainable manner is compensate for an externally induced pre-existing rotation, in the long term inevitable even in deep space, especially when slingshotting around. To correct that you need to eject mass, i.e. thrusters.

10. #### Big Thumbs Up

This has to be one of my favourite pieces of science/technology. The imagination to conceive the mission. Professionals dedicating their entire careers to an (by today's standards) unimaginably long payback period. The ingenious solutions to hiccups along the way. The brilliant revelations on the outer planets and their moons. It just goes on....

Here's to Voyager, and the other deep, deep space probes. All alone in the night...

11. #### Orbit

Is an eventually fuel-less Voyager not subject to orbital gravitational forces, no matter how weak? What orbit should Voyager eventually settle into?

1. #### Re: Orbit

Maybe the local cluster or the Galaxy. Search "Escape velocity". You don't need continued thrust to escape a "gravity well" once you are going fast enough from the start. I think the gas giants were used to speed up Voyagers and Horizon by "sling shot" effect.

The recent interstellar rock that passed relatively close to the Sun has no fuel and isn't in a Solar orbit.

1. #### Re: Orbit

At Neptune's orbit the escape velocity of the Sun is about 6km/s, Voyager 1 was doing about 19km/s then.

So Voyager 1 is leaving the solar system for sure.

1. #### Re: Orbit

So Voyager 1 is leaving the solar system for sure.

What the EU and all?

1. #### Re: Orbit

Yeah, and that black hole known as the EC/EU in Brussels.....

Paris, because she's said to have a heavenly body.....

12. #### https://voyager.jpl.nasa.gov/mission/status/

For those not aware of this site:

https://voyager.jpl.nasa.gov/mission/status/

13. #### V'Ger

So the Queller Drive worked again after all this time. I'm glad they waited until it was a long long way away before they fired it up!

PS I wonder if it now has V'Ger written on the side?

PPS Yes, I do watch too much sci-fi...

1. #### Re: V'Ger

"Yes, I do watch too much sci-fi..."

Didn't know that was possible?

2. #### Re: V'Ger

+1 for the Space 1999 reference

3. #### Re: V'Ger

Um. Queller drive. Space 1999 Series 1?

Let me look it up.

Ah yes. S1E6 Voyagers Return. Excellent. Have an upvote.

14. #### Good BBC prog

http://www.bbc.co.uk/programmes/b09gvnty

1. #### Re: Good BBC prog

Good? Amazing show. Never realised how central a role was played by Carl Sagan, for example in getting it to take a shot of earth as it flew out to interstellar space.

My take away from the show was that Voyager will be still flying onwards long after our sun expands and wipes us off the map. We will be outlived by a machine we made back in the 70s.

1. #### Re: Good BBC prog

Now if only they could get it to make a collect (reversed charges) call to the speaking clock.....

(Closest I could find to Zaphod - well, he DID steal a spaceship.....).

15. Ford can't even get my 2 year old car engine to start when I want it to.

1. So ask Zaphod. After all, two heads are better than one.

I'll get my coat. The one with the eBook and eThumb in the pocket.

Or Arthur. Marvin's probably been talking to it.....

16. #### Well done NASA!

Once again incredible engineering from NASA. Imagine anything made today lasting that long, thanks to the throwaway society and planned obsolescence. Make you proud to be a human being...

1. This post has been deleted by its author

2. #### Re: Well done NASA!

Technically, Voyager has been thrown* away. A very very very long way away.

* = by planets, via gravity, as they don't have arms.

1. #### Re: Well done NASA!

" by planets"

Almost as good as a Soviet-era Russian woman shot-putter.

2. #### Re: Well done NASA!

Air to the thrown?

3. #### Re: Well done NASA!

Actually, the mars rovers are performing staggeringly well and have throughly exceeded their planned lifetimes. Planetary environments, such as Mars, are considerably nastier on components than (relatively) empty space.

17. #### Ancient assembler code checked out

....Why the surprise that code worked? Makes it sound like time can turn good code bad. I still have my first commercial program written in 1985 and I reckon that will also work as well.

1. #### Re: Ancient assembler code checked out

True, but the specific bit of assembler that commanded those specific bits of hardware was probably never called with these specific parameters before.

2. #### Re: Ancient assembler code checked out

....Why the surprise that code worked?

Because the modern users are unfamiliar with decades-old software and could screw it up?

1. #### Re: Ancient assembler code checked out

Great. Now Satan Nutella will force a Windoze 1 0 update on it.....

3. #### Re: Ancient assembler code checked out

Indeed .. my first commercial code from 1983 runs happily in BeebEm:

http://www.mkw.me.uk/beebem/

18. #### A little bit faster

Amazing piece of hardware, and kudo's to the peeps decyphering an ancient assembler. Makes you wonder where they found the manual. One remark though. The speed is 17km / sec not per hour ;)

1. #### Re: A little bit faster

"Makes you wonder where they found the manual."

Here? https://en.wikipedia.org/wiki/Rosetta_Stone#/media/File:Rosetta_Stone.JPG

19. V'ger

20. #### "Yes, move 0xFF to the register at position IX+0xBEEF"

Testing that hypothesis was a job for software developers, as Jet Propulsion Laboratory chief engineer Chris Jones said “The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters."

Shurely assembler languages never become "outdated". They are just mnemonics for machine instructions and don't need to carry around the whole "ecosystem" of compilers, optimizers, frameworks, deployment infrastructure and consultants.

Well, ok, now we have typed assembly language, and about time too. But still.

1. #### "don't need to carry around the whole "ecosystem" of compilers, "

And how do you turn those mnemonics into machine code? Sure, you can do it by hand, but to avoid mistakes you usually use a compiler... I don't believe they sent Voyager the assembly code and it compiled it before executing it...

1. #### Re: "don't need to carry around the whole "ecosystem" of compilers, "

No, you just "assemble" it. That's why it is called "assembler" and it's a program of a few KByte (basically a parser and a lookup table manager).

"Compiling" is something a tad more complex.

1. #### Re: "don't need to carry around the whole "ecosystem" of compilers, "

Yep, it was all straightforward until some clown came up with... MacroAssembler

2. #### Re: "Yes, move 0xFF to the register at position IX+0xBEEF"

>and don't need to carry around the whole "ecosystem" of compilers, optimizers, frameworks, deployment infrastructure and consultants.

But when working on bespoke hardware, it is useful to have a precision ruler: Even with the clock speeds being used back in the early 80's, I encountered timing problems where the outermost parts of a circuit board where operating several clock cycles behind the CPU. The ruler helped me to identify which components were affected.

21. #### Here's a thought...

Has anyone built a Voyager emulator? Potentially, you could model the entire machine and then slap it in a simulated solar system...

1. #### Re: Here's a thought...

Just be sure to exit through the window, not through the door.

1. #### Re: Here's a thought...

And if someone with a Cheshire Cat smile named Zarniwhoop smiles that smile at you, punch it.....

2. #### Re: Here's a thought...

Has anyone built a Voyager emulator? Potentially, you could model the entire machine and then slap it in a simulated solar system...

We did. Thank you for being part of our solar system simulation.

Non

Antiquated

Sturdy

Apparatus

1. #### Re: NASA

NASA;

Nearly

Antiquated

Sturdy

Apparatus

This is rocketscience; we need to be precise.

23. #### It's good to see your tax money being spent

Too bad it's not being spent on any problems of real relevance.

1. #### Re: It's good to see your tax money being spent

Knowledge is always relevant. Imagine if Voyager had hit the heliopause and just blipped out of existence because its location variable was trying to access memory in the UniverSim that was dedicated to another process. Would that have been wasted money?

It didn't happen but it could have; that would have told us all manner of interesting things.

1. #### Re: It's good to see your tax money being spent

Shockingly, I do not accept low-grade science fiction speculation as justification for spending taxpayers' money.

Nor should any other taxpayers accept this blatant theft of their hard-earned money.

Since you seem to find it worthy of your rather poor attempt at being 'clever', I can only assume that you do not pay tax.

1. #### Re: It's good to see your tax money being spent

You must a Repugnican;anything you personally can't make a buck on is useless. Luckily, your kind lost at the end of the dark ages, or the renaissance would never have occurred. Although, since that would mean the western hemisphere would never have been "discovered" by Europeans I suppose the Native Americans would have been happier.

1. #### Re: It's good to see your tax money being spent

You must be particularly obtuse. I am not a Republican, nor am I an American.

Luckily your kind will have no more influence on our future apart from more of those tiresome petitions to bring back 'Firefly', or whatever.

2. #### Re: It's good to see your tax money being spent

"You must a Repugnican;"

Sounds more like a flat earther.

2. #### Re: It's good to see your tax money being spent

>Shockingly, I do not accept low-grade science fiction speculation as justification for spending taxpayers' money.

Not a fan of Dr Who or Douglas Adams then...

3. #### Re: It's good to see your tax money being spent

I seem to have struck a nerve. If NASA wish to replace the ageing RTG design with a commentard with steam coming out of its ears as a power source, do give me a shout. Just think of me as that neutron that pushes the reaction to criticality...

2. #### Re: It's good to see your tax money being spent

Too bad it's not being spent on any problems of real relevance.

It should be spent on pointless wars, Congressional pork projects, or.....???? What's being spent here is pocket change in the overall scope of government spending.

1. #### Re: It's good to see your tax money being spent

Don't blame me if the govt. spend money on things you don't approve of. Contact your MP / Representative / Senator / whatever.

You *do* know who that is, don't you?

24. I can't see the thing sailing endlessly on, it'll slow down and come to a stop when the fuel runs out. And another thing, I'm surprised the valves on the engines haven't rusted through by now.

1. I really hope you just forgot to use the Joke/Troll icon!

1. Sorry!

2. Oh dear your physics is really not good, it and nothing cannot rust, no oxygen, no water, and very very cold. Slow down, it cannot, it is not driven, it is now a celestial unit just going at its current speed, direction etc unless it is affected by something else eg smashing into something or being pulled by say a planet.

There is a caveat, perhaps you also think the moon is driven by gasoline, and that it has its steering set on going around a bend! Look out folks the earth is running out of gasoline! Duh!

25. #### Good old electronics

I still have a calculator which was made before Voyager 1 passed Jupiter. It's a Sharp Elsi Mate EL-5801 with a green display. Need I add that it works as well as the thrusters?

1. #### Re: Good old electronics

"I still have a calculator which was made before Voyager 1 passed Jupiter. It's a Sharp Elsi Mate EL-5801 with a green display. Need I add that it works as well as the thrusters?"

Probably because it has lead in the solder mix :-)

1. #### Re: Good old electronics

Yes modern solder is absolute manure, most electronic failures today are apparently due to crap unleaded solder. Now here is a thought, is it better to have an item last for 30 years, or have a one fail every year or so and be thrown away. To me even though the lead is a bit more harmful over all surely 10 or 20 times more rubbish is worse.

I have a vintage Land rover, she smokes a bit however how much pollution is created for making a new car. say a modern car lasts 15 years, then there is likely to have been about 4 new cars and the scrapping thereof just to equate to my Land Rover that incidentally is easier to maintain, does not have technical bits that go wrong (poor solder) and just keeps going.

26. #### Curious about the record

I know it's meant to help any alien civ that finds it learn about us humans and all that. But how would such a record actually be played? I mean, if it was a "typical" LP, the receiving civ has to understand how mechanics, electrics and sound well enough to build a record player, and if they understand all that, they surely know enough about electricity and magnetism to know that there is a boatload of radio signal noise coming from a small blue dot over yonder? Those signals would have arrived well before the Voyager probe showed up.

So maybe the record is sort of an apology for the noise that has been seeping into the ether? A kind of "yeah , sorry about those Alvin Stardust radio broadcasts. Here's a Chuck Berry record. This should be better."

1. #### Re: Curious about the record

I know it's meant to help any alien civ that finds it learn about us humans and all that. But how would such a record actually be played? I mean, if it was a "typical" LP, the receiving civ has to understand how mechanics, electrics and sound well enough to build a record player, and if they understand all that, they surely know enough about electricity and magnetism to know that there is a boatload of radio signal noise coming from a small blue dot over yonder? Those signals would have arrived well before the Voyager probe showed up.

There are instructions for decoding the record on the case, although expecting an alien race to be able to decipher them struck me as ambitious at best.

As for radio emissions I suspect you are thinking in terms of the wrong timescale: there is a small radioactive sample on board to allow the probe's age to be determined from its decay. It is designed to be readable for billions of years. I doubt we'll still be around, yet alone transmitting radio.

27. What are the chances of a civilization seeing and retrieving either craft before it crashes into some other planet or sun?

28. #### The poor thing...

It just wants to come home...

29. Here come V'ger!

30. #### Code does not deteriorate

If code was error free decades ago, it is still error free. If there are bugs in there they were there in 1980. However, NASA spends a lot of time and money on testing – the kind of time and money most projects don't have.

So it is not surprising that code written and working in 1980 still works today. Hardware deteriorates, so that is the miracle that the hardware still worked.

This illustrates a difference between software and hardware. But bespoke hardware built and thoroughly tested for NASA at great expense would be much more rugged than modern off-the-shelf hardware that most of us use and can afford.

1. #### Re: Code does not deteriorate

Ian, true, but 40 years in a vacuum is not a gentle environment. That the hardware worked, valves opened and closed properly suggests really tested and well built hardware that only we of many years can remember. The hardware makers get my upvote. Bit rot might be a fiction but hardware degradation is all too familiar.

1. #### Re: Code does not deteriorate

even bit rot requires a radiation source to provide the energy and there is only one, very nearby. So since bit rot would be self-inflicted I assume they designed the nuclear battery and the storage to stay out of each other's hair.

31. #### "...until something nasty stops them."

Well, it could be "Something wonderful".

32. #### Assembly?

Really?? Who uses THAT old shit? That's unreadable, unmaintainable, and not NEARLY the correct monthly flavor.

They should have used Java. Programmers are much more common, and so what if it's big and slow? That's what the swap area is for. But it's READABLE. MAINTAINABLE. And when it throws a traceback error, you know exactly where the problem is. Or use Docker and multi-thread it, so that one process does not kill the entire machine.

Besides, you have the Java/Docker automatic update feature, so you can make sure not bugs appear in the supporting language. Jeesh, it's like you guys never learned anything from a guy at home sitting in his underwear who knows much more than the PhDs that have supported this over the decodes.

Assembly? Sheesh, it's like you're LOOKING for an excuse to stay employed.

I suppose NEXT you'll tell me it's untouchable, so in a pinch I can't attach an RS-232 adapter for emergency debugging. Just what kind of supposed Microsoft graduate engineers ARE you, anyway?

33. "last used in 1980"

wish I could remember why this gave me deja vous -

1. Stuart21551

I'm still trying to decide if "deja vous" is deliberate or not.

34. #### Interesting skit about the "record".

Saturday Night Live back in the 70's announced that they had received a message from someone who intercepted the Voyager probe. They held up a card that said:

SEND MORE CHUCK BERRY

Oh, and he was a guest of JPL at the "finish" party after the Neptune encounter.

35. #### Also, it was 1972 tech ...

If you reverse the explosion in tech, you quickly get very primitive.

It's worth noting that the actual tech in the Voyagers was frozen in 1972. It could actually still be 4-bit (haven't checked).

36. #### Even wear and tear...

...requires something to play with and there isn't

anything

or

any

one

out

.

.

.

there

37. #### What is speed relative to?

Question and one that used to wind my physics teachers up. What pray is the speed relative to. To have a given speed then it must be able to be compared with something that relative to the moving object is stationary. So please pray tell me in the universe which object is stationary. For example, if a gun on the satellite was fired say in the direction of travel at 700mph, is the bullet going at the speed of the satellite +700 or is the bullet going to come out of the back of the rifle. it cannot go backwards it must go forwards so if light was projected back to earth would it be at what speed.

You see the radio waves which travel at the speed of light get to the unit and come back, therefore in space there must be a "stationary" whatever that may be. A point in time, a geographic point. There now some body explain that. No person not even serious boffins have been able to explain it.

38. #### Voyageur is starting to shorten its length!

BTW, It is not well known that the "golden disk" aboard Voyager actually started out in 1980 as a cylinder! (as did most record disks in the early 1900s)

But the Fitzgerald Contraction is now starting to have its way. -

There once was a fencer named Fisk,

Whose speed was incredibly brisk.

So fast was his action,

The Fitzgerald contraction,

Foreshortended his foil to a disk.

39. An update on 22 March 2018