Would there not be some kind of benefit to send a chaser after the probes in order to act as a relay as the signal gets further away? Or is the ground based array just as good as anything we could put in space at this time?
The voyager probes were built in an incredible hurry to take advantage of a once-in-a-few hundred years optimal gravitational boosting path. Something launched later would never have been able to keep up, plus the antenna would be so, so much worse. The ground reptilian networks have effective antenna lengrhs of miles.
I'm reading Pale Blue Dot to my kids at night currently so this is really awesome. (The Voyager missions are described in excellent detail in ways that I never appreciated fully before.)
It blows my mind that these are machines from the 8-track era. And they have fallbacks and redundancies that were completely ahead of their time.
NASA loves to downplay expectations in case something goes wrong, but people really underappreciate just how overengineered these things are, which makes sense when a bad mission can be political suicide for their future funding.
Single digit dollar sounds more like the Appollo program. I think it's been a long time since the entire NASA budget was more than a penny per tax dollar.
NASA says the voyager mission cost 865 million dollars from the start in 1972 to Neptune encounter in 1989, and currently runs at 7 mllion dollars per year.
Cool! I do the same thing with books like Asimov’s Earth and Space (science) or Lois Lowry’s Number the Stars (fictional history). What other books can you recommend?
One feels a terrible disappointment Sagan didn't live to see the future mission projects he talks about in the book get finished and most of them succeeded IIRC. By happenstance the 2024 Solar System BBC series mostly uses animation but has some real photos and videos to document a lot of happened since the book was published.
The last time I read Cosmos I hit the part about the Cassini-Huygens mission where he wondered what we might find under the atmosphere of Titan, and was able to immediately just find out.
I imagine a lot of people who work on space missions do not outlive their work - which feels sad but also ... inspiring?
Yeah it's really amazing that these come from a time where normal people had never even heard of bits and bytes. And now they're the furthest man made objects and their data link still works.
I didn’t realize the Voyagers relied on a once in a 175 year planetary alignment. What a lucky break technology had advanced to the point we could make use of it.
It wasn't just a lucky break, it was the result of furious efforts by scientists to lobby years in advance to take advantage of the alignment, as well as engineers who repurposed two Mariner probes to save money, as well as canny NASA bureaucrats who sneakily downplayed the possibility of a full Grand Tour in order to reduce estimated costs (with the full intent to underpromise and overdeliver, which Voyager 2 successfully did by "coincidentally" being on course to visit Neptune and Uranus after completing its primary mission to Jupiter and Saturn (to this day, Voyager 2 remains the only visitor to Uranus and Neptune)).
Still a huge amount of luck involved. If that planetary alignment had happened even 10 years earlier NASA probably wouldn't have had the capability to do anything with it. If it had been sometime recently, say after the Challenger disaster, I doubt it would have got funding...
if they used the same booster, say something like a Falcon 9, that was the cause of the disaster, anything using that booster would be put on hold until it was cleared. it just so happens the examples used very different systems, but that's not what you were referring to with your self assured declarative that just doesn't have as much weight as you want it to in modern launch systems.
Not just any foreword, a pretty big endorsement. You can borrow the book from the internet archive to read the full foreword, but here's the last bit:
And in the end, it turns out that something will happen in 1982 that just may—
No, no, read it for yourself. Read it carefully and you'll find it far more fascinating than the tale of any millionaire found stabbed in any library, locked or otherwise. And far more important, too especially if you live in California.
ISAAC ASIMOV
17 April 1974
The scenario where a gravity assist doesn't work is if turning sharply enough would require your minimum planetcentric approach distance to be less than the radius of the planet - you'd crash into it instead.
This is why Voyager 2 couldn't also do Pluto - it would have needed to change course by roughly 90º at Neptune, which would have required going closer to the center of Neptune than Neptune's own radius.
The most unusual gravity-assist alignment that we did was for Pioneer 11 going from Jupiter to Saturn. The encounters were separated by roughly 120º of heliocentric longitude. Pioneer 11 used Jupiter to bend its path "up" out of the ecliptic plane and encountered Saturn on the way back "down". Nowadays we wouldn't bother doing that (we'd wait for a more direct launch window instead), but the purpose of this was to get preliminary Jupiter and Saturn encounters done in time before Voyager's launch window for the grand tour alignment.
Could Voyager have reduced velocity, glanced off Neptune, waited for the return path on a narrow elliptical orbit, and then boosted to effectively make the 90° turn to Pluto at that time? Was that impossible given its Neptune approach trajectory, or would glancing off and waiting have been more fuel?
And, why didn't this vortical model that includes the forward velocity of the sun make a difference for Voyager's orbital trajectory and current position relative to earth? https://news.ycombinator.com/item?id=42159195 :
Breaking that down: Voyager itself couldn't have reduced velocity, it had nowhere near enough reaction mass to do that. Hypothetically a spacecraft could but you might be talking about orders of magnitude more reaction mass. (Which means multiples more of the fuel to launch and accelerate that mass itself, which could quickly escalate beyond any chemical rocket capabilities.)
It also likely wasn't possible to get to Pluto on some future Pluto orbital pass. The limiting factor is likely that Voyager's incoming trajectory to Neptune was already too far beyond solar escape velocity to get into that narrow elliptical orbit you propose. (You'd have to slingshot so close to Neptune's center that you'd hit the planet instead.)
Designing from the beginning to come in slower to Neptune and adjust to encounter Pluto on some future Pluto orbital pass was probably possible, but yeah you might be talking about time scales of Pluto's entire orbit or even multiples of that. (We do similar things for inner solar system missions, like several encounters with Venus separated by multiple Venus-years, but that's on the order of single-digit years and not hundreds.)
The common answer to a lot of these outlandish slingshot questions is usually, yes it's eventually possible by orbital mechanics, but it gets so complicated and lengthy that you may as well just build another separate spacecraft instead. We talk about Voyager's grand tour alignment because it's captivating, but realistically if that hadn't happened we would have just done separate Jupiter-Uranus and Jupiter-Neptune missions instead.
The sun's motion relative to the galaxy doesn't matter for any of this - nothing else in the galaxy is remotely close enough to affect anything, the nearest star is still over 1000x Voyager's distance.
The alignment greatly reduced the amount of energy/propellant/weight to launch the Voyager missions with all four of the outer planets on the menu. Alignments that allow you to reach a smaller set of the outer planets with the same budget are more common: years or decades.
(Edit) Another thought, since you mentioned time—numerical computing power and the math required to exercise it have advanced greatly since the 1970s, and it's likely that some of the trajectories and maneuvers feasible (again with the same fuel budget) today, even if they took 100+ years to complete, weren't even calculable back then.
No, there's no pingponging. There's only so much momentum you can exchange with a planet, because there's only so close a flyby that you can make before it stops being a flyby and becomes a fly-into.
The alignment was important because it allowed visiting four planets with one spacecraft. So you only had to launch one spacecraft. (We launched two anyway.)
If you are willing to launch four spacecrafts to visit four planets, the alignment restrictions are much relaxed. You do need to be careful about your launch window to get a nice boost, but it's measured in years between windows, not so much centuries.
> The alignment was important because it allowed visiting four planets with one spacecraft. So you only had to launch one spacecraft. (We launched two anyway.)
IIRC the second probe was mainly intended as a backup to the first one, but visiting Titan and visiting Uranus/Neptune were mutually exclusive, and visiting Titan was higher priority, so if the first probe succeeded the backup could be (and was) sent on the four planet track.
Ignoring the feasibility of the physics, imagine trying to calculate all the resulting trajectories to point antennas at to talk to the probe. With computers and equipment of the 1970s.
“We didn’t design them to last 30 years or 40 years, we designed them not to fail,” John Casani, Voyager project manager from 1975 to 1977, says in a NASA statement.
> this is HN, a bunch of computer programmers think they know more than <figure of authority>
And they are correct
At least on the programming part, having in mind the huge advances in computers since the Voyager was built. Any professional computer programmer here knows more about their field than a programmer from 70's.
Voyager 1 was a fantastic machine done by a terrific team, but lets not pretend that the state of the art hasn't changed. A Voyager built today with similar resources would be much better, 100% guaranteed.
Anybody with computer skills polished toward building a machine in 1977 would be basically unemployable for building a machine in 2024.
You don’t do it that way. You figure out the how it’s gong to fail, when that failure is likely, and then engineer it not to do that in the relevant timeframe.
Incidentally, you have the question backwards: no one really cares when it's going to fail. We care when it's not going to fail: will the spacecraft make it to its destination or not? It doesn't really matter what happens after that.
This might seem like a nitpick, but changes in approach and mindset like this are often the difference between success and failure with "impossible" problems like this. So it's critical to get your approach right!
>Nothing lasts forever, and if you don't figure out when it's going to fail, it's going to be sooner rather than later.
You might be surprised about the reality of the situation.
I had a professor who worked on the design and fabrication of the Apollo Guidance Computers, which likely was a somewhat similar process to the one being discussed here. It's been quite a few years since his lecture on it, but the process went something like this:
They started with an analysis of the predicted lifetime/reliability of every chip type/component available to potentially include in the design.
The design was constrained to only use components with the top x% of predicted life.
Then they surveyed each manufacturer of each of those component types to find the manufacturer with the highest lifetime components for each of the highest lifetime component types.
Then they surveyed the manufacturing batches of that manufacturer, to identify the batches with the highest lifetimes from that manufacturer.
Then they selected components from the highest lifetime batches of from the highest lifetime manufacturers of the highest lifetime components.
Using those components, they assembled a series of guidance computers, in batches.
They tested those batches, pushing units from each batch to failure.
They then selected the highest quality manufacturing batch as the production units.
When he gave this talk, decades after the Apollo era, NASA had been continuing to run lifetime failure analyses on other units from the production batch, to try to understand the ultimate failure rate for theoretical purposes.
Several decades after the Apollo program ended, they had still never seen any failure events in these systems, and shortly before the time of his lecture, I believe NASA had finally shut off the failure testing of these systems, as they were so remote from then "modern" technology (this was decades ago, hence the quotes around "modern").
This is what happens when you have the best minds committed to designing systems that don't fail. Yes, the systems probably will fail before the heat death of the universe. No, we don't have any idea when that failure time will be. Yes, it's likely to be a very long time in the future.
(And, of course, this is typed from memory about a lecture decades ago on events happening decades before that. This being HN, someone here probably worked on those systems, in which case hopefully they can add color and fix any defects in the narrative above).
FWIW his quote also applies to a lotta devices here on Earth. For example guns are not designed to last forever, but they are designed not to fail. You don't want to hear a click when you expect a bang or vice versa. As a side effect, they last forever. It's fairly common for a 100 year old gun to work perfectly in 2024.
It's fascinating how Voyager 1, despite my lack of space knowledge, utilizes a nuclear power source for 40+ years, offering steady and reliable power without any moving parts that could degrade over time.
In contrast, India's decision to rely on solar panels led vikram lander to be dead in just 14 days due to lack of sunlight (afaik).
I'm curious about the rationale behind this choice when nuclear power seems like a far superior option. Can someone shed light on this decision?
First, the nuclear power source is a giant hunk of plutonium. It is expensive to get, dangerous to use, and due to concerns about further refinement, is restricted internationally.
Second, it is toxic inherently — the source is continuously radioactive at a hazardous level to humans, plutonium itself has acute and long-term toxic effects aside from the radioactivity, and if a launch fails, the rtg will disintegrate and poison hundreds of miles (see Kosmos 954, which disintegrated over Canada)
Third, it is HEAVY. They produce 40W per kilogram. Solar panels produce three times that much on Mars, and can be folded compact for launch.
Voyager used an RTG because its planned mission took it far beyond where sunlight can generate power, and it could do so because it had the budget of NASA and plutonium from the Department of Energy.
Solar panels are way cheaper, lighter, easier to procure, easier to launch, and tend not to cause international incidents.
I wonder if you could do a hybrid approach, where the nuclear device is very small, but able to charge the battery over a longer duration to the point where the solar panels can be repositioned and utilized again.
Lots of missions use radioisotopic heaters, where you don't bother with the thermocouples and just have the material get warm and protect components which are vulnerable to low temperatures.
That's the main reason why spacecraft don't survive a temporary power outage: terrible environmentals.
But at this point, we don't have a lot of Pu-238, which is one of the only decent candidates.
Kosmos-954 didn't poison hundreds of miles, square or otherwise.
They could only find a dozen of radioactive bits, each only dangerous within a very small area around it, and not really leaching anything due to its ceramic nature. Most of the fuel dispersed and became harmless by dilution, probably never even reached the surface.
I don't know the exact reasons why Vikram didn't get a fission reactor. But I can assume from similar missions:
1. Solar is pretty good as far as Mars and it gets worse as it travel further from the Sun. This is why most probes that travel past Mars need a nuclear reactor (Voyager, Pioneer, Cassini, etc). Going closer to the sun they get even better
2. Sending radioactive materials on rockets presents a risk and it is avoided if possible, lunar probes are usually cheaper and can still benefit from solar, so no need for nuclear. Imagine throwing plutonium in the atmosphere in the case of an accident
3. Nuclear reactors in probes are small and rely on decay radiation, they _usually_ have pretty small powet output, solar has a lot
4. And last but not least, price, solar is much cheaper than nuclear
Am I wrong that the plutonium in the Voyagers is not in a fission reactor but in an RTG (Radioisotope Thermoelectric Generator), which converts the heat from the plutonium into electricity. ?
I suppose the heat is result of fission, but I don't think an RTG is what is meant by a fission reactor. ??
Using plutonium works great but there are two issues. 1) they don’t output that much power. Few hundred watts at most, and they decay at a fixed rate. 2) you need to get your hands on a decent amount of plutonium. Great for dirty bombs, hard to source.
Both Canada and the US have restarted production specifically to produce RTGs for NASA, but the process takes time to scale up and automate. It's gone up 4x in 4 years and continues to increase, so this is a problem that will eventually be "fixed".
Isn't it something like space-reactor plutonium is a waste product from nuclear weapons production, and since we don't really make nuclear weapons at scale anymore, we aren't really making (refining?) plutonium anymore. And NASA has some amount on reserve, but they're rationing it out carefully. So the Clipper probe had to go with a massive solar array (100ft, the length of a basketball court) because they would rather save their plutonium for some future rover mission.
RTGs need plutonium 238. I've read even US doesn't have a lot available. The Europa Clipper will be using solar panel for example. India could also use batteries and a standby mode during the 14 days without sunlight. But any extra weight would add to the launch cost. Maybe in future missions as they get confident with successful landing, they will have bigger lander that can survive the lunar night. Even the early Mars rovers from NASA were tiny and solar powered (ie Sojourner in 1997.)
A good reason is the lack of availability of the needed isotope (Pu238).
The Europa Clipper has a huge array of solar panels instead of an RTG due to the last of the available supply going into the New Horizons spacecraft.
Pu238 was a cast-off isotope from nuclear weapons development so it was more readily available during the cold war. We should be happy that it's scarce now.
Also solar panels have gotten a lot better than they were when Voyager was launched, but even today anything going out past Saturn is not going to be able to use solar energy.
Availability :) a RTG requires Plutonium 238, which needs to ne created almost on purpose in a nucleare reactor. Not all nations have this ability or they are running such expensive programs. Also in the USA they are reserved for programs where there is very little light available
Can we send a voyager 3 with much advance battery and sensor, and at much faster speed so that it may reach farther than voyager 1 and 2, in let’s say just couple of years ?
1. Our rocket / propulsion technology today may be cheaper (thx largely to SpaceX), but it doesn't really necessarily provide MUCH more delta V. Meanwhile
2. Voyager launches relied on a once-in-a-blue-moon (not quite once in two centuries) alignment of various planetary bodies to give a spectacular orbital slingshot boosts.
So my limited understanding is that we can't really overtake voyagers very easily. Whether our current technology coild be made more reliable in the long term is another good point of discussion :-)
The alignment isn't what matters for overtaking Voyager. Jupiter alone is enough, and New Horizons nearly did. Jupiter accounts for the vast majority of any gravity-assist plan. Saturn has 30% the mass and 2/3 of the orbital velocity, so it could only add 20% more over what you get from Jupiter alone, and the ice giants are smaller and slower yet.
New Horizons didn't nearly overtake Voyager. It's currently traveling about 4 km/s slower, and as it's still closer to the Sun, it's also decelerating more.
Yes, I wrote that short for brevity. If you must have the full thing spelled out: New Horizons nearly got enough velocity at Jupiter to eventually overtake Voyager. 4 km/s is "nearly" in astronomical terms. New Horizons wasn't really trying to optimize for speed at Jupiter (its closest approach was over 10m km), and a spacecraft that did could easily overtake Voyager using Jupiter alone and not need an alignment with Saturn or anything else.
As far as I understand their speed mostly comes from gravity assists from Jupiter, so you'd have to wait for suitable orbital alignments and the basic technology for "much faster speed" doesn't exist.
> the basic technology for "much faster speed" doesn't exist.
…but we’re very close. The next technique will be flying near the sun then deploying a solar sail for a huge speed boost. Voyager goes 3 AU/yr, solar sail boost with todays technology will enable 7-9 AU/yr.
Highly recommend watching Slava Turyshev discuss his work on an SGL telescope, which employs this technique.
> and the basic technology for "much faster speed" doesn't exist.
Various forms of nuclear propulsion have been investigated. None of them are anywhere near ready for missions, but that seems to be more due to lack of investment in their development (and environmental/legal/regulatory/geopolitical/etc concerns) than any scientific obstacle. If NASA/etc were really serious about it (as in willing to spend multiple billions a year on it), it could probably be made to work in only a few years.
This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact. Moon is an option here, so likely it’s 5-15 years after first Moon base is established (I‘d expect exponential growth of it).
> This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact
The idea pursued nowadays is you launch using chemical propulsion and then only turn on the nuclear propulsion once you reach a safe distance from Earth. This is different from the original 1950s Project Orion which proposed to use nuclear pulse propulsion (i.e. repurposing nuclear weapons for propulsion) from the surface to orbit, which would have produced enough fallout to likely kill a handful of people per launch (in the long-run through higher cancer rates). The question then is - is it safe to launch nuclear material to orbit using chemical propulsion? Yes, we can secure it in containers designed to survive catastrophic loss of the launch vehicle. But, will the general public believe it is safe, even if it actually is? Possibly not-which is a political obstacle rather than a technical one.
The other issue is that nuclear propulsion systems can be too large/heavy to launch on a single chemical rocket, but you could launch them as multiple modules assembled together in orbit.
I don’t think this need or should depend on off-Earth manufacturing or mining capacity. I think it is going to be a long time before the highly complex manufacturing supply chains needed to turn raw materials into cutting edge technology like nuclear space propulsion systems exists off Earth. But we should be able to manufacture them modularly on Earth, such that in space we’d be doing module assembly rather than manufacturing.
Strictly speaking, the voyager missions already are the faster space craft that caught up with another spacecraft - Pioneer 10 and 11.
Looks like we lost contact with 10 and 11 in 1995 and 2006 respectively. They both ran out of power and shut down.
The voyager missions used a rare planetary alignment to get boosts. And a radioisotope thermal engine that has gotten pushback in later spacecraft designs, although they have ceramic versions now meant to address most of the issues.
That said, New Horizons, which gave us those lovely shots of Pluto, was launched in 2006. But it is traveling faster than the Pioneers but slower than Voyagers, so it’ll be the third farthest away at some point.
Not a couple of years. The Voyagers have been doing around 38 000 mph since the late 1970's. That is rougly 17 km/s. The proposed Interstellar Probe mission aims to do 20 km/s or slightly more. It will take it decades to overtake any of them (no actual overtaking will probably take place though, as its trajectory most likely will be different).
We could make a Voyager 3, but I don't think there is any way to expect it to catch up with currently feasible technology. And it could only be launched at specific times.
It certainly could have more advanced sensors and batteries. I don't know if the battery improvement would really matter on a decades long mission.
As others have pointed out, the speeds for Voyager 1 were because of gravity assist of Jupiter and Saturn while Voyager 2 was a gravity assist of Jupiter, Saturn, Uranus and Neptune. Jupiter & Saturn line up relatively often enough so we could try to outdo Voyager 1 speeds a bit with a lighter air craft due to various advancements. But it's unclear we'd learn anything really new from having sensors that reached further out and our technology for propulsion really hasn't meaningfully advanced to outdo gravity assists from Jupiter + Saturn. There's some proposals to use nuclear explosions behind a probe to achieve speeds of ~10k km/s which would be substantially faster but there's numerous obstacles (cost + international treaties banning the use of nuclear in space).
Yes, but mostly no, also no, and, frankly, why would we.
Yes: we could lift off a much heavier spacecraft, give it plenty of fuel, and many of its parts would be lighter than their 1970s equivalent, giving us lots of room for modern sensors
Also no: the old Voyagers benefited from a lot of gravity assists from half the solar system, thanks to an alignment which won't happen again until 2151 (https://space.stackexchange.com/questions/5075/when-is-the-n...), so unless you're not in a hurry, we won't have that.
Why would we: the _point_ of the Voyager crafts was to do close flybys and collect plenty of data from the outer planets, not to go as far away and as fast as possible. You want to be as slow as possible near them, so you have science time. You're rushing this part in order to get right away to the centuries of nothing which follow?
Just a small aside, are Stirling engines used on other spacecraft? The Wikipedia article suggests development was largely abandoned a decade ago. My first glance concern would be that because it's reliant on moving parts it is liable to fail sooner than a purely thermoelectric RTG (due to part wear, lubricant leaks, fatigue, etc). This would seem to be quite important on the timeline of a probe that is going to take a long time to reach the subject of its investigation.
Which, to your point, only works against the idea of hypothetical Voyager 3.
Unfortunately a gravity assist maneuver is almost "incompatible" with an ion thruster.
If you approach e.g. Jupiter you gain speed (it's pulling you in), which you then lose as you get away from it (as it's still pulling you in, meh). Gravity assists work because you use your chemical rocket right when you are closest and speed away, "robbing" Jupiter of the chance to claim the energy it lent you on approach.
Ion thrusters have very low thrust, so you would accelerate veeeeery slowly away from Jupiter's gravity well - and in this time it will keep affecting you and slowing you down, and the whole thing would be barely worth doing.
You could bolt on a very simple solid rocket booster just for the gravity assist, of course, but its ISP will be lower and you'll have to carry its mass until you can expend it.
I think you are mixing up gravity assist with the oberth effect. I'm pretty sure Voyagers did no massive burns close to the giant planets for example. A (so far theoretical) Solar Oberth maneuver on the other hand...
Even if we could there isn't much point. There just isn't very much out where the Voyagers are, and there won't be for a long time. We're shutting down sensors on Voyager because there just isn't much to see. It's just vacuum.
If we had something capable of getting to Voyager in a year that might be worthwhile, because it would stand a chance of getting somewhere interesting in a few decades. But we are absolutely nowhere near that level.
Were engineers 50 years ago just much smarter than we are now? It’s pretty unbelievable that these things still work. Or is there something systemic about how they were able to achieve so much so long ago with basically no computers to help.
They had lot less resources and knowledge to estimate the right amount of resilience for achieving the mission goals and erred on the side of cautions.
You can see something similar happening in bridges, weight per meter load has come down considerably since the 60s because material understanding is much more advanced and they meed less margin for the same safety factor.
> The Kurilpa Bridge is a multiple-mast, cable-stay structure based on principles of tensegrity producing a synergy between balanced tension and compression components to create a light structure which is incredibly strong.
Delighted to see this here — the Kurilpa Bridge is less than 50 meters from my front door and is something to behold each time I get the chance to use it.
There was much less overall complexity (and capability). These engineers interacted directly with capacitors and circuits to accomplish their tasks. Integrated circuits enable a lot of modern society, but it also segregates engineering between fabrication time and everything afterwards.
I find that more analogue / mechanical type machines even more amazing in someways. Like how they say it ‘decided’ to switch to its backup radio. How are those decisions made on such basic hardware? I guess thinking mechanically is just a very foreign concept for me mostly making software
>Were engineers 50 years ago just much smarter than we are now?
Were the 2006 sony santa monica programmers smarter then us when they delivered God of War 2 for the PS2 on its tiny resources?
Usually the constraints force you to become inventive and smart. Put a hard limit of 128 mb per tab on web browsers and suddenly both the developers of the browsers and the web developers will become extremely smart.
The over abundance of resources has made the majority of software engineers lazy. If we once again live in scarcity times - suddenly people will start to ask why we need 8 abstraction layers to do something.
I would guess they were quite smart bunch, but no superhuman - just people tasked with extremely challenging task, trying to jury rig something on the edge of possibility. My guess is that they took their tasks more seriously and to heart.
It's not nonsense. Many of the radio receiver setups made use of diversity or dual-diversity configurations. Also, transmitter and receiver blocks from different manufacturers were wired in switchable primary/backup configurations.
We have to way to know it it's actually the fastest and farthest object: A 1957 nuclear test was conducted underground, but the scientists decided to cap the borehole with a sizable concrete and metal plug.
The nuclear explosion may or may not have caused said plug to reach space - the data from the cameras indicate it had at least 6 times the needed escape velocity, but it is difficult to estimate whether it would completely disintegrate or if enough of it would survive the atmosphere and whether it would "count"
I was struggling trying to think up any other plausible scenario, where one unit in a continiously operating piece of electronic /hard/soft ware was rebooted
after such a long time
and Voyager most likely has no competition
in this regard or in a number of others
sure speaks volumes for how well the nasa crew ,knew there stuff, and got it right
durring that era,on budget,on time, and now doing inter generational space research
making the actual designs and blue prints of the space craft, very much worth re examinining
AFAIK launch vehicle cost were never the problem for deep space probes. Launch windows still are - Voyager was extremely lucky in this regard. And then there is probe design and construction - SpaceX made launches cheaper, but that just shift most of the cost into the payload. And then there is no point in having such a fleet if you there isn't enough funding for scientists to process the results.
Most of the probes would be identical. Building two identical probes would cost only marginally more than 1, perhaps 10% more.
> but that just shift most of the cost into the payload
It reduces the cost, not shift it.
> And then there is no point in having such a fleet if you there isn't enough funding for scientists to process the results.
Plenty of funding would become available if the funding for junk science stops, such as:
"In 2021, the National Institutes of Health (NIH) awarded $549,000 to a Russian lab performing experiments on cats, including removing part of their brains and seeing if they could still walk on treadmills, according to the Washington Times." https://nypost.com/2024/11/13/us-news/where-elon-musk-can-st...
Is there some existing plan? A paper that supports this idea? It's not clear to me that the probe we send to one place for one purpose is the same we'd send to another.
> Building two identical probes would cost only marginally more than 1, perhaps 10% more.
I've read from experts - somewhere here on HN - that isn't how the costs work.
> Plenty of funding would become available if the funding for junk science stops, such as
> "In 2021, the National Institutes of Health (NIH) awarded $549,000 to a Russian lab performing experiments on cats, including removing part of their brains and seeing if they could still walk on treadmills, according to the Washington Times." https://nypost.com/2024/11/13/us-news/where-elon-musk-can-st...
$500k is not enough to matter for a space probe, and I don't see why that brain research is junk science. If you truly think the research was about half-brained cats, then you really should appreciate that research. :D
Would there not be some kind of benefit to send a chaser after the probes in order to act as a relay as the signal gets further away? Or is the ground based array just as good as anything we could put in space at this time?
Wouldn't it be difficult as one would need large antennas and excellent alignment?
Voyager to earth is "relatively" easy it "just" beams toward the sun. And earth can afford to get big antennas scanning.
No, their RTGs are almost exhausted anyway so soon they won't have enough power to run anything.
The voyager probes were built in an incredible hurry to take advantage of a once-in-a-few hundred years optimal gravitational boosting path. Something launched later would never have been able to keep up, plus the antenna would be so, so much worse. The ground reptilian networks have effective antenna lengrhs of miles.
I'm reading Pale Blue Dot to my kids at night currently so this is really awesome. (The Voyager missions are described in excellent detail in ways that I never appreciated fully before.)
It blows my mind that these are machines from the 8-track era. And they have fallbacks and redundancies that were completely ahead of their time.
NASA loves to downplay expectations in case something goes wrong, but people really underappreciate just how overengineered these things are, which makes sense when a bad mission can be political suicide for their future funding.
It was also incredibly on budget. I think Sagan says in the book it cost the individual American taxpayers in the single digit dollars.
Single digit dollar sounds more like the Appollo program. I think it's been a long time since the entire NASA budget was more than a penny per tax dollar.
NASA says the voyager mission cost 865 million dollars from the start in 1972 to Neptune encounter in 1989, and currently runs at 7 mllion dollars per year.
So that would be $7.72 per taxpayer, a single-digit dollar amount.
(based on number of taxpayers in 1989 -- using the numbers from 1972, it would be a low double-digit amount).
Totalled up, yes - fair enough.
Cool! I do the same thing with books like Asimov’s Earth and Space (science) or Lois Lowry’s Number the Stars (fictional history). What other books can you recommend?
Good question but I have a fever at the moment so unfortunately my brain is not fully functioning :/
One feels a terrible disappointment Sagan didn't live to see the future mission projects he talks about in the book get finished and most of them succeeded IIRC. By happenstance the 2024 Solar System BBC series mostly uses animation but has some real photos and videos to document a lot of happened since the book was published.
The last time I read Cosmos I hit the part about the Cassini-Huygens mission where he wondered what we might find under the atmosphere of Titan, and was able to immediately just find out.
I imagine a lot of people who work on space missions do not outlive their work - which feels sad but also ... inspiring?
Yeah it's really amazing that these come from a time where normal people had never even heard of bits and bytes. And now they're the furthest man made objects and their data link still works.
I didn’t realize the Voyagers relied on a once in a 175 year planetary alignment. What a lucky break technology had advanced to the point we could make use of it.
It wasn't just a lucky break, it was the result of furious efforts by scientists to lobby years in advance to take advantage of the alignment, as well as engineers who repurposed two Mariner probes to save money, as well as canny NASA bureaucrats who sneakily downplayed the possibility of a full Grand Tour in order to reduce estimated costs (with the full intent to underpromise and overdeliver, which Voyager 2 successfully did by "coincidentally" being on course to visit Neptune and Uranus after completing its primary mission to Jupiter and Saturn (to this day, Voyager 2 remains the only visitor to Uranus and Neptune)).
Still a huge amount of luck involved. If that planetary alignment had happened even 10 years earlier NASA probably wouldn't have had the capability to do anything with it. If it had been sometime recently, say after the Challenger disaster, I doubt it would have got funding...
There's no way that a disaster on a manned mission would affect a satellite launch. They share nothing in common.
if they used the same booster, say something like a Falcon 9, that was the cause of the disaster, anything using that booster would be put on hold until it was cleared. it just so happens the examples used very different systems, but that's not what you were referring to with your self assured declarative that just doesn't have as much weight as you want it to in modern launch systems.
The paper for it is readable - Fast Reconnaissance Missions to the Outer Solar System Derived from the Gravitational Field of Jupiter http://www.gravityassist.com/IAF3-2/Ref.%203-143.pdf (1966)
Also fun to play with is: https://trajbrowser.arc.nasa.gov/index.php (example query with multiple flybys of outer planets - https://trajbrowser.arc.nasa.gov/traj_browser.php?NEAs=on&NE... )
And I remember the "crazies" saying the world will come to an end due to that alignment. That belief was reported in the main stream media.
When it did not happen, I think they moved on to 2012 :)
Ah, yes - The Jupiter Effect: https://www.goodreads.com/book/show/3400930-the-jupiter-effe...
Forward by Isaac Asimov? I'm surprised he would have his name associated with this.
Not just any foreword, a pretty big endorsement. You can borrow the book from the internet archive to read the full foreword, but here's the last bit:
I’m trying to figure out why the alignment was so important.
Wouldn’t it be possible to get a gravity assist in any alignment - albeit just taking a little longer to ping-pong across the system?
The scenario where a gravity assist doesn't work is if turning sharply enough would require your minimum planetcentric approach distance to be less than the radius of the planet - you'd crash into it instead.
This is why Voyager 2 couldn't also do Pluto - it would have needed to change course by roughly 90º at Neptune, which would have required going closer to the center of Neptune than Neptune's own radius.
The most unusual gravity-assist alignment that we did was for Pioneer 11 going from Jupiter to Saturn. The encounters were separated by roughly 120º of heliocentric longitude. Pioneer 11 used Jupiter to bend its path "up" out of the ecliptic plane and encountered Saturn on the way back "down". Nowadays we wouldn't bother doing that (we'd wait for a more direct launch window instead), but the purpose of this was to get preliminary Jupiter and Saturn encounters done in time before Voyager's launch window for the grand tour alignment.
Could Voyager have reduced velocity, glanced off Neptune, waited for the return path on a narrow elliptical orbit, and then boosted to effectively make the 90° turn to Pluto at that time? Was that impossible given its Neptune approach trajectory, or would glancing off and waiting have been more fuel?
And, why didn't this vortical model that includes the forward velocity of the sun make a difference for Voyager's orbital trajectory and current position relative to earth? https://news.ycombinator.com/item?id=42159195 :
> "The helical model - our solar system is a vortex" https://youtube.com/watch?v=0jHsq36_NTU
Breaking that down: Voyager itself couldn't have reduced velocity, it had nowhere near enough reaction mass to do that. Hypothetically a spacecraft could but you might be talking about orders of magnitude more reaction mass. (Which means multiples more of the fuel to launch and accelerate that mass itself, which could quickly escalate beyond any chemical rocket capabilities.)
It also likely wasn't possible to get to Pluto on some future Pluto orbital pass. The limiting factor is likely that Voyager's incoming trajectory to Neptune was already too far beyond solar escape velocity to get into that narrow elliptical orbit you propose. (You'd have to slingshot so close to Neptune's center that you'd hit the planet instead.)
Designing from the beginning to come in slower to Neptune and adjust to encounter Pluto on some future Pluto orbital pass was probably possible, but yeah you might be talking about time scales of Pluto's entire orbit or even multiples of that. (We do similar things for inner solar system missions, like several encounters with Venus separated by multiple Venus-years, but that's on the order of single-digit years and not hundreds.)
The common answer to a lot of these outlandish slingshot questions is usually, yes it's eventually possible by orbital mechanics, but it gets so complicated and lengthy that you may as well just build another separate spacecraft instead. We talk about Voyager's grand tour alignment because it's captivating, but realistically if that hadn't happened we would have just done separate Jupiter-Uranus and Jupiter-Neptune missions instead.
The sun's motion relative to the galaxy doesn't matter for any of this - nothing else in the galaxy is remotely close enough to affect anything, the nearest star is still over 1000x Voyager's distance.
The alignment greatly reduced the amount of energy/propellant/weight to launch the Voyager missions with all four of the outer planets on the menu. Alignments that allow you to reach a smaller set of the outer planets with the same budget are more common: years or decades.
(Edit) Another thought, since you mentioned time—numerical computing power and the math required to exercise it have advanced greatly since the 1970s, and it's likely that some of the trajectories and maneuvers feasible (again with the same fuel budget) today, even if they took 100+ years to complete, weren't even calculable back then.
No, there's no pingponging. There's only so much momentum you can exchange with a planet, because there's only so close a flyby that you can make before it stops being a flyby and becomes a fly-into.
The alignment was important because it allowed visiting four planets with one spacecraft. So you only had to launch one spacecraft. (We launched two anyway.)
If you are willing to launch four spacecrafts to visit four planets, the alignment restrictions are much relaxed. You do need to be careful about your launch window to get a nice boost, but it's measured in years between windows, not so much centuries.
> The alignment was important because it allowed visiting four planets with one spacecraft. So you only had to launch one spacecraft. (We launched two anyway.)
IIRC the second probe was mainly intended as a backup to the first one, but visiting Titan and visiting Uranus/Neptune were mutually exclusive, and visiting Titan was higher priority, so if the first probe succeeded the backup could be (and was) sent on the four planet track.
Ignoring the feasibility of the physics, imagine trying to calculate all the resulting trajectories to point antennas at to talk to the probe. With computers and equipment of the 1970s.
Speed run hacking
> scientists and engineers back on Earth have increasingly had to deal with age-related maintenance issues
There is perhaps unintended irony in that sentence, but it does evoke some Asimov stories in which human characters age while supporting technology.
I like this quote:
“We didn’t design them to last 30 years or 40 years, we designed them not to fail,” John Casani, Voyager project manager from 1975 to 1977, says in a NASA statement.
I would expect a mindful trade-off against total system mass and cost.
That doesn't seem helpful. Nothing lasts forever, and if you don't figure out when it's going to fail, it's going to be sooner rather than later.
Maybe the guy who helped launch the two manmade objects furthest from earth knows more about how to build space probes than you
Shhhh, this is HN, where just like on reddit, a bunch of computer programmers think they know more than a professional in said professional's field.
> this is HN, a bunch of computer programmers think they know more than <figure of authority>
And they are correct
At least on the programming part, having in mind the huge advances in computers since the Voyager was built. Any professional computer programmer here knows more about their field than a programmer from 70's.
Voyager 1 was a fantastic machine done by a terrific team, but lets not pretend that the state of the art hasn't changed. A Voyager built today with similar resources would be much better, 100% guaranteed.
Anybody with computer skills polished toward building a machine in 1977 would be basically unemployable for building a machine in 2024.
You don’t do it that way. You figure out the how it’s gong to fail, when that failure is likely, and then engineer it not to do that in the relevant timeframe.
The original engineer was right and you are not.
Incidentally, you have the question backwards: no one really cares when it's going to fail. We care when it's not going to fail: will the spacecraft make it to its destination or not? It doesn't really matter what happens after that.
This might seem like a nitpick, but changes in approach and mindset like this are often the difference between success and failure with "impossible" problems like this. So it's critical to get your approach right!
>Nothing lasts forever, and if you don't figure out when it's going to fail, it's going to be sooner rather than later.
You might be surprised about the reality of the situation.
I had a professor who worked on the design and fabrication of the Apollo Guidance Computers, which likely was a somewhat similar process to the one being discussed here. It's been quite a few years since his lecture on it, but the process went something like this:
They started with an analysis of the predicted lifetime/reliability of every chip type/component available to potentially include in the design.
The design was constrained to only use components with the top x% of predicted life.
Then they surveyed each manufacturer of each of those component types to find the manufacturer with the highest lifetime components for each of the highest lifetime component types.
Then they surveyed the manufacturing batches of that manufacturer, to identify the batches with the highest lifetimes from that manufacturer.
Then they selected components from the highest lifetime batches of from the highest lifetime manufacturers of the highest lifetime components.
Using those components, they assembled a series of guidance computers, in batches.
They tested those batches, pushing units from each batch to failure.
They then selected the highest quality manufacturing batch as the production units.
When he gave this talk, decades after the Apollo era, NASA had been continuing to run lifetime failure analyses on other units from the production batch, to try to understand the ultimate failure rate for theoretical purposes.
Several decades after the Apollo program ended, they had still never seen any failure events in these systems, and shortly before the time of his lecture, I believe NASA had finally shut off the failure testing of these systems, as they were so remote from then "modern" technology (this was decades ago, hence the quotes around "modern").
This is what happens when you have the best minds committed to designing systems that don't fail. Yes, the systems probably will fail before the heat death of the universe. No, we don't have any idea when that failure time will be. Yes, it's likely to be a very long time in the future.
(And, of course, this is typed from memory about a lecture decades ago on events happening decades before that. This being HN, someone here probably worked on those systems, in which case hopefully they can add color and fix any defects in the narrative above).
A testament to requirements and quality. Thanks for sharing this insight, cheers!
> This is what happens when you have the best minds committed to designing systems that don't fail.
Given how times have changed, perhaps it is also valuable to note that other major-yet-unwritten factor: confidence in the supply chain.
>This is what happens when you have the best minds committed to designing systems that don't fail.
And a budget to support them.
FWIW his quote also applies to a lotta devices here on Earth. For example guns are not designed to last forever, but they are designed not to fail. You don't want to hear a click when you expect a bang or vice versa. As a side effect, they last forever. It's fairly common for a 100 year old gun to work perfectly in 2024.
I imagine there are cases which exemplify your point, but this does not look like one of them.
It's fascinating how Voyager 1, despite my lack of space knowledge, utilizes a nuclear power source for 40+ years, offering steady and reliable power without any moving parts that could degrade over time.
In contrast, India's decision to rely on solar panels led vikram lander to be dead in just 14 days due to lack of sunlight (afaik).
I'm curious about the rationale behind this choice when nuclear power seems like a far superior option. Can someone shed light on this decision?
Sure!
First, the nuclear power source is a giant hunk of plutonium. It is expensive to get, dangerous to use, and due to concerns about further refinement, is restricted internationally.
Second, it is toxic inherently — the source is continuously radioactive at a hazardous level to humans, plutonium itself has acute and long-term toxic effects aside from the radioactivity, and if a launch fails, the rtg will disintegrate and poison hundreds of miles (see Kosmos 954, which disintegrated over Canada)
Third, it is HEAVY. They produce 40W per kilogram. Solar panels produce three times that much on Mars, and can be folded compact for launch.
Voyager used an RTG because its planned mission took it far beyond where sunlight can generate power, and it could do so because it had the budget of NASA and plutonium from the Department of Energy.
Solar panels are way cheaper, lighter, easier to procure, easier to launch, and tend not to cause international incidents.
I wonder if you could do a hybrid approach, where the nuclear device is very small, but able to charge the battery over a longer duration to the point where the solar panels can be repositioned and utilized again.
Lots of missions use radioisotopic heaters, where you don't bother with the thermocouples and just have the material get warm and protect components which are vulnerable to low temperatures.
That's the main reason why spacecraft don't survive a temporary power outage: terrible environmentals.
But at this point, we don't have a lot of Pu-238, which is one of the only decent candidates.
Kosmos-954 didn't poison hundreds of miles, square or otherwise.
They could only find a dozen of radioactive bits, each only dangerous within a very small area around it, and not really leaching anything due to its ceramic nature. Most of the fuel dispersed and became harmless by dilution, probably never even reached the surface.
I don't know the exact reasons why Vikram didn't get a fission reactor. But I can assume from similar missions:
1. Solar is pretty good as far as Mars and it gets worse as it travel further from the Sun. This is why most probes that travel past Mars need a nuclear reactor (Voyager, Pioneer, Cassini, etc). Going closer to the sun they get even better
2. Sending radioactive materials on rockets presents a risk and it is avoided if possible, lunar probes are usually cheaper and can still benefit from solar, so no need for nuclear. Imagine throwing plutonium in the atmosphere in the case of an accident
3. Nuclear reactors in probes are small and rely on decay radiation, they _usually_ have pretty small powet output, solar has a lot
4. And last but not least, price, solar is much cheaper than nuclear
> fission reactor
Am I wrong that the plutonium in the Voyagers is not in a fission reactor but in an RTG (Radioisotope Thermoelectric Generator), which converts the heat from the plutonium into electricity. ?
I suppose the heat is result of fission, but I don't think an RTG is what is meant by a fission reactor. ??
Voyager uses a RTG. The USSR used some full-on nuclear reactors in space, but as far as I know no one else publicly did.
The US put a fission reactor in space too. They did it first, in fact: https://en.wikipedia.org/wiki/SNAP-10A
Edit: it’s apparently still there and will be for a long time (!) albeit non-functional:
Using plutonium works great but there are two issues. 1) they don’t output that much power. Few hundred watts at most, and they decay at a fixed rate. 2) you need to get your hands on a decent amount of plutonium. Great for dirty bombs, hard to source.
Both Canada and the US have restarted production specifically to produce RTGs for NASA, but the process takes time to scale up and automate. It's gone up 4x in 4 years and continues to increase, so this is a problem that will eventually be "fixed".
Isn't it something like space-reactor plutonium is a waste product from nuclear weapons production, and since we don't really make nuclear weapons at scale anymore, we aren't really making (refining?) plutonium anymore. And NASA has some amount on reserve, but they're rationing it out carefully. So the Clipper probe had to go with a massive solar array (100ft, the length of a basketball court) because they would rather save their plutonium for some future rover mission.
it don't make sense to stock hot plutonium to use it later, it loose power and decays overtime wherever you use it or not!
RTGs need plutonium 238. I've read even US doesn't have a lot available. The Europa Clipper will be using solar panel for example. India could also use batteries and a standby mode during the 14 days without sunlight. But any extra weight would add to the launch cost. Maybe in future missions as they get confident with successful landing, they will have bigger lander that can survive the lunar night. Even the early Mars rovers from NASA were tiny and solar powered (ie Sojourner in 1997.)
India is a nuclear armed-nation with some long-standing border tensions with some of their also nuclear-armed neighbors.
The military probably have priority on the decisions about the allocations of their plutonium stocks.
A good reason is the lack of availability of the needed isotope (Pu238).
The Europa Clipper has a huge array of solar panels instead of an RTG due to the last of the available supply going into the New Horizons spacecraft.
Pu238 was a cast-off isotope from nuclear weapons development so it was more readily available during the cold war. We should be happy that it's scarce now.
Also solar panels have gotten a lot better than they were when Voyager was launched, but even today anything going out past Saturn is not going to be able to use solar energy.
There was just an article about a whole array of “nuclear batteries” using all sorts of decent chemistry: https://news.ycombinator.com/item?id=42118306
Are any of those candidates or are they just too small or with too poor a mass ratio compared to plutonium RTGs?
Availability :) a RTG requires Plutonium 238, which needs to ne created almost on purpose in a nucleare reactor. Not all nations have this ability or they are running such expensive programs. Also in the USA they are reserved for programs where there is very little light available
> I'm curious about the rationale behind this choice when nuclear power seems like a far superior option. Can someone shed light on this decision?
India’s plutonium has already been spoken for.
Dead in 14 days? Was there a miscalculation that lead them to believe they could make one full night?
Discussed earlier:
"NASA reconnected with Voyager 1 after a brief pause" (30.10.2024)
https://news.ycombinator.com/item?id=41992394
I’m not saying it’s true but I really feel like I see this article once or twice a year. I’m not sure what’s going on.
I think there’ve been at least two recent episodes of trouble, including this one. I feel like I’ve seen more than two articles about it though.
Can we send a voyager 3 with much advance battery and sensor, and at much faster speed so that it may reach farther than voyager 1 and 2, in let’s say just couple of years ?
My understanding is that
1. Our rocket / propulsion technology today may be cheaper (thx largely to SpaceX), but it doesn't really necessarily provide MUCH more delta V. Meanwhile
2. Voyager launches relied on a once-in-a-blue-moon (not quite once in two centuries) alignment of various planetary bodies to give a spectacular orbital slingshot boosts.
So my limited understanding is that we can't really overtake voyagers very easily. Whether our current technology coild be made more reliable in the long term is another good point of discussion :-)
The alignment isn't what matters for overtaking Voyager. Jupiter alone is enough, and New Horizons nearly did. Jupiter accounts for the vast majority of any gravity-assist plan. Saturn has 30% the mass and 2/3 of the orbital velocity, so it could only add 20% more over what you get from Jupiter alone, and the ice giants are smaller and slower yet.
> New Horizons nearly did.
New Horizons didn't nearly overtake Voyager. It's currently traveling about 4 km/s slower, and as it's still closer to the Sun, it's also decelerating more.
Yes, I wrote that short for brevity. If you must have the full thing spelled out: New Horizons nearly got enough velocity at Jupiter to eventually overtake Voyager. 4 km/s is "nearly" in astronomical terms. New Horizons wasn't really trying to optimize for speed at Jupiter (its closest approach was over 10m km), and a spacecraft that did could easily overtake Voyager using Jupiter alone and not need an alignment with Saturn or anything else.
As far as I understand their speed mostly comes from gravity assists from Jupiter, so you'd have to wait for suitable orbital alignments and the basic technology for "much faster speed" doesn't exist.
> the basic technology for "much faster speed" doesn't exist.
…but we’re very close. The next technique will be flying near the sun then deploying a solar sail for a huge speed boost. Voyager goes 3 AU/yr, solar sail boost with todays technology will enable 7-9 AU/yr.
Highly recommend watching Slava Turyshev discuss his work on an SGL telescope, which employs this technique.
https://www.youtube.com/live/lqzJewjZUkk?si=57VS4oqbaKEXmyOR
> and the basic technology for "much faster speed" doesn't exist.
Various forms of nuclear propulsion have been investigated. None of them are anywhere near ready for missions, but that seems to be more due to lack of investment in their development (and environmental/legal/regulatory/geopolitical/etc concerns) than any scientific obstacle. If NASA/etc were really serious about it (as in willing to spend multiple billions a year on it), it could probably be made to work in only a few years.
This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact. Moon is an option here, so likely it’s 5-15 years after first Moon base is established (I‘d expect exponential growth of it).
> This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact
The idea pursued nowadays is you launch using chemical propulsion and then only turn on the nuclear propulsion once you reach a safe distance from Earth. This is different from the original 1950s Project Orion which proposed to use nuclear pulse propulsion (i.e. repurposing nuclear weapons for propulsion) from the surface to orbit, which would have produced enough fallout to likely kill a handful of people per launch (in the long-run through higher cancer rates). The question then is - is it safe to launch nuclear material to orbit using chemical propulsion? Yes, we can secure it in containers designed to survive catastrophic loss of the launch vehicle. But, will the general public believe it is safe, even if it actually is? Possibly not-which is a political obstacle rather than a technical one.
The other issue is that nuclear propulsion systems can be too large/heavy to launch on a single chemical rocket, but you could launch them as multiple modules assembled together in orbit.
I don’t think this need or should depend on off-Earth manufacturing or mining capacity. I think it is going to be a long time before the highly complex manufacturing supply chains needed to turn raw materials into cutting edge technology like nuclear space propulsion systems exists off Earth. But we should be able to manufacture them modularly on Earth, such that in space we’d be doing module assembly rather than manufacturing.
I never actually knew that. My mental model for how this works was way off; I'll have to read more.
Play Kerbal Space Program (the original, not the sequel). You’ll become an orbital mechanics pro in a couple days.
Strictly speaking, the voyager missions already are the faster space craft that caught up with another spacecraft - Pioneer 10 and 11.
Looks like we lost contact with 10 and 11 in 1995 and 2006 respectively. They both ran out of power and shut down.
The voyager missions used a rare planetary alignment to get boosts. And a radioisotope thermal engine that has gotten pushback in later spacecraft designs, although they have ceramic versions now meant to address most of the issues.
That said, New Horizons, which gave us those lovely shots of Pluto, was launched in 2006. But it is traveling faster than the Pioneers but slower than Voyagers, so it’ll be the third farthest away at some point.
> let’s say just couple of years ?
Not a couple of years. The Voyagers have been doing around 38 000 mph since the late 1970's. That is rougly 17 km/s. The proposed Interstellar Probe mission aims to do 20 km/s or slightly more. It will take it decades to overtake any of them (no actual overtaking will probably take place though, as its trajectory most likely will be different).
No, we cannot.
We could make a Voyager 3, but I don't think there is any way to expect it to catch up with currently feasible technology. And it could only be launched at specific times.
It certainly could have more advanced sensors and batteries. I don't know if the battery improvement would really matter on a decades long mission.
> at much faster speed
As others have pointed out, the speeds for Voyager 1 were because of gravity assist of Jupiter and Saturn while Voyager 2 was a gravity assist of Jupiter, Saturn, Uranus and Neptune. Jupiter & Saturn line up relatively often enough so we could try to outdo Voyager 1 speeds a bit with a lighter air craft due to various advancements. But it's unclear we'd learn anything really new from having sensors that reached further out and our technology for propulsion really hasn't meaningfully advanced to outdo gravity assists from Jupiter + Saturn. There's some proposals to use nuclear explosions behind a probe to achieve speeds of ~10k km/s which would be substantially faster but there's numerous obstacles (cost + international treaties banning the use of nuclear in space).
Yes, but mostly no, also no, and, frankly, why would we.
Yes: we could lift off a much heavier spacecraft, give it plenty of fuel, and many of its parts would be lighter than their 1970s equivalent, giving us lots of room for modern sensors
No: the "battery" in the old ones is nuclear and it's going to be difficult to beat that (but not impossible: a nuclear stirling engine, either powered by fission or by decay, e.g. https://www.nasa.gov/technology/rps/stirling-convertor-sets-...)
Also no: the old Voyagers benefited from a lot of gravity assists from half the solar system, thanks to an alignment which won't happen again until 2151 (https://space.stackexchange.com/questions/5075/when-is-the-n...), so unless you're not in a hurry, we won't have that.
Why would we: the _point_ of the Voyager crafts was to do close flybys and collect plenty of data from the outer planets, not to go as far away and as fast as possible. You want to be as slow as possible near them, so you have science time. You're rushing this part in order to get right away to the centuries of nothing which follow?
Just a small aside, are Stirling engines used on other spacecraft? The Wikipedia article suggests development was largely abandoned a decade ago. My first glance concern would be that because it's reliant on moving parts it is liable to fail sooner than a purely thermoelectric RTG (due to part wear, lubricant leaks, fatigue, etc). This would seem to be quite important on the timeline of a probe that is going to take a long time to reach the subject of its investigation.
Which, to your point, only works against the idea of hypothetical Voyager 3.
We probably do not need to wait for ideal planets position to outrun Voyagers. We have ion thruster now with much higher specific impulse!
Voyager-2 gained about 10 km/s at Jupiter, about 5 km/s at Saturn, about 2 km/s at Uranus, and lost about 2 km/s at Neptune. [1]
Dawn spacecraft gained 11.5 km/s from ion thrusters.
So just gravity assist maneuver just around Jupiter alone + massive tank for ion thrusters gas might give 20+ km/s
Though I agree that value of such a mission would be low.
[1] https://www.planetary.org/articles/20130926-gravity-assist
Unfortunately a gravity assist maneuver is almost "incompatible" with an ion thruster.
If you approach e.g. Jupiter you gain speed (it's pulling you in), which you then lose as you get away from it (as it's still pulling you in, meh). Gravity assists work because you use your chemical rocket right when you are closest and speed away, "robbing" Jupiter of the chance to claim the energy it lent you on approach.
Ion thrusters have very low thrust, so you would accelerate veeeeery slowly away from Jupiter's gravity well - and in this time it will keep affecting you and slowing you down, and the whole thing would be barely worth doing.
You could bolt on a very simple solid rocket booster just for the gravity assist, of course, but its ISP will be lower and you'll have to carry its mass until you can expend it.
I think you are mixing up gravity assist with the oberth effect. I'm pretty sure Voyagers did no massive burns close to the giant planets for example. A (so far theoretical) Solar Oberth maneuver on the other hand...
> the "battery" in the old ones is nuclear and it's going to be difficult to beat that
Newer atomic batteries can theoretically last centuries instead of decades.
V'ger 1 atomic battery is based on Plutonium-238 which has a halflife of ~88 years. It's down to ~210W output from initial 470W at launch time.
Americium-241 has a half-life of over 400 years.
The longer the half life, the lower the power output, no free lunches. But by putting the same suitable radioactive lump in a stirling engine you can extract 4 times as much electricity: https://en.wikipedia.org/wiki/Stirling_radioisotope_generato...
So yes maybe with Americium-241 we could have something which lasts 4 times a much _and_ gives us the same amount of power thanks to a SRG.
Using a sterling motor would give you mechanical wear.
But it seems to involve moving parts, so I am not sure the reliability trade-off is worth it for decades/centuries long missions.
Finding “V’ger” hilarious.
Even if we could there isn't much point. There just isn't very much out where the Voyagers are, and there won't be for a long time. We're shutting down sensors on Voyager because there just isn't much to see. It's just vacuum.
If we had something capable of getting to Voyager in a year that might be worthwhile, because it would stand a chance of getting somewhere interesting in a few decades. But we are absolutely nowhere near that level.
> We're shutting down sensors on Voyager because there just isn't much to see.
That's not why Voyager's sensors are being shut down, they're being shut down because the probes no longer have the power to run them.
Not in our lifetimes
Worth a watch, imo:
It's Quieter in the Twilight
https://www.space.com/nasa-voyager-mission-engineers-documen...
Interesting trying to manage their declining power budget. And decipher docs written 40+ years ago.
This stuff will never not blow my mind.
Were engineers 50 years ago just much smarter than we are now? It’s pretty unbelievable that these things still work. Or is there something systemic about how they were able to achieve so much so long ago with basically no computers to help.
They had lot less resources and knowledge to estimate the right amount of resilience for achieving the mission goals and erred on the side of cautions.
You can see something similar happening in bridges, weight per meter load has come down considerably since the 60s because material understanding is much more advanced and they meed less margin for the same safety factor.
Our understanding of physics has also gotten much better, for example our understanding of tensegrity. https://en.wikipedia.org/wiki/Kurilpa_Bridge
> The Kurilpa Bridge is a multiple-mast, cable-stay structure based on principles of tensegrity producing a synergy between balanced tension and compression components to create a light structure which is incredibly strong.
Delighted to see this here — the Kurilpa Bridge is less than 50 meters from my front door and is something to behold each time I get the chance to use it.
There was much less overall complexity (and capability). These engineers interacted directly with capacitors and circuits to accomplish their tasks. Integrated circuits enable a lot of modern society, but it also segregates engineering between fabrication time and everything afterwards.
I find that more analogue / mechanical type machines even more amazing in someways. Like how they say it ‘decided’ to switch to its backup radio. How are those decisions made on such basic hardware? I guess thinking mechanically is just a very foreign concept for me mostly making software
Golden NASA budgets might have helped…
NASA missions still routinely overperform. Curiosity's been operational on Mars for a good 12 years now.
>Were engineers 50 years ago just much smarter than we are now?
Were the 2006 sony santa monica programmers smarter then us when they delivered God of War 2 for the PS2 on its tiny resources?
Usually the constraints force you to become inventive and smart. Put a hard limit of 128 mb per tab on web browsers and suddenly both the developers of the browsers and the web developers will become extremely smart.
The over abundance of resources has made the majority of software engineers lazy. If we once again live in scarcity times - suddenly people will start to ask why we need 8 abstraction layers to do something.
I would guess they were quite smart bunch, but no superhuman - just people tasked with extremely challenging task, trying to jury rig something on the edge of possibility. My guess is that they took their tasks more seriously and to heart.
They weren't affected by DEI nonsense yet.
It's not nonsense. Many of the radio receiver setups made use of diversity or dual-diversity configurations. Also, transmitter and receiver blocks from different manufacturers were wired in switchable primary/backup configurations.
That thing just won't die!
It's too bad this cant qualify as some sort of world record
We have to way to know it it's actually the fastest and farthest object: A 1957 nuclear test was conducted underground, but the scientists decided to cap the borehole with a sizable concrete and metal plug.
The nuclear explosion may or may not have caused said plug to reach space - the data from the cameras indicate it had at least 6 times the needed escape velocity, but it is difficult to estimate whether it would completely disintegrate or if enough of it would survive the atmosphere and whether it would "count"
https://nuclearweaponarchive.org/Usa/Tests/Plumbob.html (look for Pascal-B)
Calculations show that it was completely destroyed in the atmosphere. Which makes sense, cause meteorites of similar size don't make it to the ground.
It was also slower, 150,000 mph, than Parker Solar Probe, which reached 430,000 mph.
Could be the start of space records :-)
I was struggling trying to think up any other plausible scenario, where one unit in a continiously operating piece of electronic /hard/soft ware was rebooted after such a long time and Voyager most likely has no competition in this regard or in a number of others sure speaks volumes for how well the nasa crew ,knew there stuff, and got it right durring that era,on budget,on time, and now doing inter generational space research making the actual designs and blue prints of the space craft, very much worth re examinining
Now that we've got SpaceX cheap launches, it's time to launch a fleet of solar system probes and space telescopes.
Why isn't this happening?
AFAIK launch vehicle cost were never the problem for deep space probes. Launch windows still are - Voyager was extremely lucky in this regard. And then there is probe design and construction - SpaceX made launches cheaper, but that just shift most of the cost into the payload. And then there is no point in having such a fleet if you there isn't enough funding for scientists to process the results.
Most of the probes would be identical. Building two identical probes would cost only marginally more than 1, perhaps 10% more.
> but that just shift most of the cost into the payload
It reduces the cost, not shift it.
> And then there is no point in having such a fleet if you there isn't enough funding for scientists to process the results.
Plenty of funding would become available if the funding for junk science stops, such as:
"In 2021, the National Institutes of Health (NIH) awarded $549,000 to a Russian lab performing experiments on cats, including removing part of their brains and seeing if they could still walk on treadmills, according to the Washington Times." https://nypost.com/2024/11/13/us-news/where-elon-musk-can-st...
> Most of the probes would be identical.
Is there some existing plan? A paper that supports this idea? It's not clear to me that the probe we send to one place for one purpose is the same we'd send to another.
> Building two identical probes would cost only marginally more than 1, perhaps 10% more.
I've read from experts - somewhere here on HN - that isn't how the costs work.
> Plenty of funding would become available if the funding for junk science stops, such as
> "In 2021, the National Institutes of Health (NIH) awarded $549,000 to a Russian lab performing experiments on cats, including removing part of their brains and seeing if they could still walk on treadmills, according to the Washington Times." https://nypost.com/2024/11/13/us-news/where-elon-musk-can-st...
$500k is not enough to matter for a space probe, and I don't see why that brain research is junk science. If you truly think the research was about half-brained cats, then you really should appreciate that research. :D
Isn't most of the cost due to designing and building the probes? One launch has been routine for NASA (and others) since long before SpaceX.
See Three Body Problem (the books)
Truly amazing!!
Imagine 100 years from now they come up with a probe engine that can get to 10% the speed of light, it would only take a month to reach Voyager.
Even at only 1% it would take under a year, but lots of breakthroughs needed for even that.