NASA Power Hack Extends 45-Year Voyager 2 Mission Even Longer | Hacker News Reader

NASA Power Hack Extends 45-Year Voyager 2 Mission Even Longer

gizmodo.com

217 pointstaubek68 comments

Everything about Voyager is just mind-blowing. These are 45 year old electronic devices, using 70's tech, with zero maintenance, operating 22 light hours away.

At that range they can still send messages detectable on earth. 9 out of 10 instruments are still working. People just leaving school when they launched are already retired.

This is one time when the adage "they don't make them like they used to" is well applied.

Hat tip to all involved.

Btw, you can see the occasional communication with Voyager at https://eyes.nasa.gov/dsn/dsn.html

As I write this, one of the dishes at Madrid just went to "Setup" for communication with VGR1.

(late edit - some of the stats from the 'more info' at the bottom of the spacecraft panel)

    DATA RATE       160.0 b/sec
    POWER RECEIVED  -160 dBm (1.0 x 10-22 kW)

Agreed, but I believe Voyager is 18.5 light hours away, not 22. The article says it is 20 billion km away which is 18.5 light hours.

However the article also states signals take 22 hours to reach the spacecraft. Do radio waves travel slower than the speed of light even in the vacuum of space? I assume the waves do not spend the extra 3.5 hours in Earth's atmosphere!

I think it's because space isn't a perfect vacuum. The interstellar medium is a mix of gas and dust that slow down and weaken the signal. That effect is known as dispersion.

With that said, it seems like the article might be inaccurate. That discrepancy seems too large to be explained by dispersion. I'm not an expert though.

edit: I think the author got Voyager 1's distance mixed up with Voyager 2. Voyager 1 is ~22 (21.6) light hours away.

Sounds more like ChatGPT got it mixed up.

The article is rounding up, and the parent comment is talking about Voyager 1.

Specifically: Voyager 1 is 23.8 billion km (23.8 Tm), and Voyager 2 is 18.3 Tm.

For those that might not be aware, Voyager 2 launched before Voyager 1, so the distance discrepancy is not due to the further one being launched first

Voyager 2 was launched first but on a less direct trajectory out of the system which allowed it to visit Uranus and Neptune. Voyager 1 is going much faster

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

There is an effect called dispersion, which causes different frequencies of electromagnetic radiation to travel through a medium at different speeds (lower frequencies => slower).

It's strong enough to be noticeable in the case of pulsars (but probably insignificant inside the solar system).

Don't confused TTFB with message transport time. With a low bandwidth link, throughput becomes part of latency. Probably not 3.5 hours, but some fraction of that.

Voyager 2 had 11 instruments. 5 are still active. But still, it is a remarkable piece of technology.

I mean, with a few notable exceptions, NASA's scientific missions have an amazing record of lasting much longer than they were designed for, Hubble and the Mars rovers & helicopter being amazing feats of lasting longer then they should.

> Everything about Voyager is just mind-blowing. These are 45 year old electronic devices, using 70's tech, with zero maintenance, operating 22 light hours away.

No, what is mind blowing is that we are not able to do it again.

We did do it again. We got New Horizons out to Pluto a lot faster, without the aid of the remarkable alignment that made Voyager possible.

We keep exploring the solar system. There's no reason to repeat the same experiments. We've explored the planets in a lot more depth, and just launched even more.

Heres another article I read today that had some specifics. They are disabling a voltage regulator to save power and prioritize the science instruments as a calculated risk.

https://phys.org/news/2023-04-nasa-voyager-science-power-str...

>In search of a way to avoid shutting down a Voyager 2 science instrument, the team took a closer look at a safety mechanism designed to protect the instruments in case the spacecraft's voltage—the flow of electricity—changes significantly. Because a fluctuation in voltage could damage the instruments, Voyager is equipped with a voltage regulator that triggers a backup circuit in such an event. The circuit can access a small amount of power from the RTG that's set aside for this purpose. Instead of reserving that power, the mission will now be using it to keep the science instruments operating.

>Although the spacecraft's voltage will not be tightly regulated as a result, even after more than 45 years in flight, the electrical systems on both probes remain relatively stable, minimizing the need for a safety net. The engineering team is also able to monitor the voltage and respond if it fluctuates too much. If the new approach works well for Voyager 2, the team may implement it on Voyager 1 as well.

I'm amazed that they're able to disable a voltage regulator remotely. Did they just build in relays for every single component in case they wanted to rewire everything on the fly or was this something they specifically knew they might want to do 45 years ago?

Also I assume there isn't a web service running there with a "enable/disable" endpoint to control stuff. Wonder what the control stack looks like.

Turned up this from https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--14...:

> The signal consists of 16-bps, Manchesterencoded commands, biphase modulated onto a squarewave subcarrier frequency of 512 hertz (Hz).

There are references to fuller descriptions of the command set but I haven't found them yet.

I can't help but wonder how possible it would be (or would have been at some point in the past) for a person with evil intent to send unauthorized commands to these probes. How are signals authenticated? At this point, is it just that there are only a handful of parties capable of sending a strong enough radio signal to a precise-enough location in space, and who know the position of these probes to the degree of accuracy required?

Well, I think the first obstacle would be acquiring a sufficiently large antenna. Given that the large dishes used in the DSN are 70m (~230ft) across, I suspect somebody would notice…

They'll notice! Good thing you're doing it in North Korea where they can't do anything about it.

I buy that. But what about shortly after launch?

Your guess is as good as mine I suppose. Not many people have access to a huge antenna with huge transmitting power.

As for authentication: with 16 buts per second and 44 hours round trip, they're not doing some sort of handshake to agree an encryption key. But given these were launched during the Cold War, maybe some basic encryption perhaps, with key of course hardcoded before launch?

I highly doubt it's even authenticated. They're probably just relying on anyone with enough skill and money having easier/better things to attack.

The death of Voyager would not hurt any of America's strategic objectives. It would just make some nerds really bummed, approximately as many in your own country as in America, so what have you gained?

Just getting a piece of infrastructure that can lock onto the probe's telemetry signals is incredibly difficult.

You'll need to hack NASA's deep space network first I think. On your own and with a normal mortal's budget you're not going to be able to do much of anything.

Nowadays sure. What about shortly after launch?

Say you’re the USSR and want to quietly piss in NASA’s cornflakes. Or hell, say you’re Putin—today—and want to do the same thing. Could you?

Shortly after launch it was almost certainly not known how communication worked. And if you had a spy that could get you that info, you could just get them to press the wrong button(s) instead.

Putin has limited resources. He'd rather spend them on his stupid war, and also building other weapons and warships, rather than a giant radio antenna and a team of engineers trying to hack a 45-year-old spacecraft's communications protocol, just to screw with NASA.

I’m asking about the technical measures used to authenticate commands to these probes. The bit about Putin was just about framing the question.

Some random hobbyists (or even small nation-states) aren't going to be able to build a radio antenna large enough to communicate with deep-space probes like that. That's all the "technical measures" needed.

Got a Time Machine?

Yeah, I'd say it's actually pretty common to make spacecraft avionics as remotely switchable as possible. For one thing, there's likely to be a considerable amount of redundancy so that a single component failure doesn't ruin your whole mission. It's good practice to have a way to isolate any component that is anticipated to fail. FDIR is a known acronym: fault detection, isolation and recovery.

This could be as simple as disconnecting a zener diode from ground, but yeah, I'd be a lot interested in knowing more technical details.

They probably implemented fail-safe relays with circuitry to disengage automatically under hazardous conditions but also controlled remotely.

Exactly, and to have the foresight so long ago to architect it this way, brilliant.

Ya know...... Considering how long it takes these things to get to deep space we probably should've kept the Voyager program going. By that, I mean we should've continued iterating and launching Voyager probes. If we launched one every 2 or even 5 years we'd have between 22 and 9 additional probes heading into deep space a couple years apart. Each with slightly better tech than the previous.

There are 2 problems with this:

1. Voyager was launched at that particular time because a particular alignment of planets (known as the "Grand Tour") allowed for MASSIVE gravity assists that made this mission possible. This alignment happens very rarely (I think like ~200 years)

2. Opportunity cost. Yes we could have done this, but what would we have gained? Mostly we would get the same data over and over again. Resources are not infinite. Would you rather another Voyager mission, or Hubble?

I figured the justification was #2, and my answer is obviously give space more budget and do both, but I know the government doesn't tend to align with my priorities.

However, #1 (it's literally not possible) didn't even cross my mind and shows my naivety when it comes to space travel. Super interesting info. Thanks for sharing.

It’s “only” every 176 years ;)

I would say it's been followed up plenty of times. There have been some incredible probes with unique capabilities, that have traveled the solar system since the launch of Voyager.

Agreed. Every time I see a story about the Voyagers, I wonder why a follow-up hasn't been done that is much faster and more capable.

It's the same reason the Voyagers launched in the late 70s - the Grand Tour configuration of the planets [0]. The outer planets align in a way that lets you chain together several gravity assists to achieve high enough speeds to escape the solar system. The trick is that configuration only occurs every 175 years. I don't think we have any space vehicles right now that could produce that same kind of delta-v with their own chemical/electrical/nuclear power.

[0] - https://en.wikipedia.org/wiki/Grand_Tour_program

It's feasible to do an alternate route to the outer solar system by using an ion engine, dropping the perihelion down below Venus's orbit and then using a Venus -> Earth gravity assist chain with the ion engine going the whole time. The downside is that this is a more lengthy process than the Grand Tour route, and you have to do all your maneuvers in the inner solar system because ion engines draw a lot of electrical power and solar panels get very weak once you get past Mars or so.

Probably because it made more sense to use the general information obtained from the Voyagers to design probes with specific capabilities to explore specific planets. The Cassini/Huygens mission might be a possible example.

If there is on thing this demonstrates then it is that the combination of good documentation and clever engineering can go a long, long way.

JPL Press Release: https://www.jpl.nasa.gov/news/nasas-voyager-will-do-more-sci...

What blows my mind is that even after 40+ years, these probes are still less than 1 light day away from home. A light year is vast.

Whenever I read something related to the two Voyager probes I feel a little bit sad about them since they’re out there on their own. At the same time I feel pride for humanity as a species, since we managed to send these two probes so far away.

Getting the probe out there is no doubt indeed remarkable in its own right, but to build it resilient enough to remain communicative at this distance, after all this time in such hostile environment, along with the foresight that enables these lifetime measures to be taken almost a half century later, makes it all more remarkable, and to think all this accrued knowledge and ingenuity being generalized from things like chipping flint axes.

Video recommendation:

How To Contact The Voyager 2 Probe (https://www.youtube.com/watch?v=FzRP1qdwPKw) and

Pinging The Voyager 2 Probe (https://www.youtube.com/watch?v=1rCrfQUcXDI) by EEVDiscover

Thank you so much for these links. These are much more detailed videos than I expected going over the RF and antennas involved.

Dave! :D

Don't turn it on, take it apart!

Correction: apaaat

Does anyone know if JPL have "local copies" of Voyager 1 and 2 that they can test things like this hack on? Or do they just plan it out and try on the probes themselves?

The probes get their power from the decay of a plutonium isotope. The question is why can't we find applications for this technology on earth, for example to power your house or something?

Forget all the minor concerns about nuclear proliferation and cost. RTGs just have a very small niche of useful applications

RTGs are basically just a thermocouple stuck to a chunk of radioactive material, which gets hot. They are dramatically less efficient than a nuclear power plant, so it really doesn't make sense to use them in situations where a nuclear power plant is an option.

That limits them to relatively small things (because your submarine or ship or whatever can have a proper power plant), that can't be connected to a power grid (because you could just have your power plant elsewhere), even periodically (because you could just use batteries), that can't harness more easily available sources of power like the sun or wind, and can carry the shielding necessary to make them safe.

Ultimately, that narrows down their applicability greatly.

They evidently used to use radiothermal generators (RTGs) as the power source for some pacemakers.

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

Plutonium is nasty & expensive stuff, however. That puts some pretty severe limitations on its usefulness for domestic purposes.

RTGs in humans: not for a long time.

The USSR did that for a while. It didn't end well for some people. https://en.m.wikipedia.org/wiki/Lia_radiological_accident

> Around the canisters there was no snow for about a 1 m (3.3 ft) radius, and the ground was steaming.

I recall a discussion on HN about securing radioactive waste sites so that future, possibly illiterate, generations would understand the danger and keep off.

Reading this I'm starting to doubt it's possible. I mean, no snow and steaming ground? Clearly suspicious. And this was the 21st century - these people must have been at least vaguely aware that nuclear power exists.

Thanks for that source. Maybe it's impractical for domestic use but it looks like they found uses for it in isolated locations for industrial purposes. Obviously it needs to be handled responsibly.

> needs to be handled responsibly.

Yes, for the next 10000 years. Plutonium's half life is annoyingly long.

RTGs don't use things with 10,000 year half lives, because they need to have meaningful amounts of decay happening to make heat.

238Pu is pretty common, because it produces just alpha decay and has a half life of 87 years. Within 1000 years, the main remaining activity is 234U with a half life of 240,000 years: still an alpha emitter but much, much less active.

The problem is not finding applications. The problem is cost and safety.

In space they make sense because as you go far enough away from the sun, solar power is negligible. Since it costs a lot to launch, the cost of the RTG itself isn't such a big deal. And you only have to worry about safety for a little while.

Relying on the thermoelectric effect, they're horribly inefficient. Here on earth we have other options that are more efficient, cost less and is way safer.

The heat may be inherently useful for keeping the spacecraft warm enough to operate, mitigating some of that inherent inefficiency.

They have a lot of advantages, but they are extraordinarily expensive, screamingly radioactive, require nuclear weapons technology to manufacture, and are inefficient in the amount of energy you put in vs. get out.

Even for space missions, the tradeoff of just using solar panels (which have a ton of problems in space) is often worth it. It's not easy to get an RTG approved for your multi-billion dollar space mission.

It's a very small, but stable, amount of power generated given the amount of plutonium and the costs/risks of it it's not really worth it for anything else. Geothermal for instance for a home would make much much sense.

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