What you are describing has been proposed before, for example within context of projects like Breakthrough Starshot. In that the case the idea is to launch thousands of probes, each weighing only a few grams or less, and accelerating them to an appreciable fraction of the speed of light using solar sails and (powerful) earth-based lasers. The probes could reach alpha centauri within 20-30 years. There seems to be some debate though about whether cross-links between probes to enable relaying signals is ever practical from a power and mass perspective vs a single very large receiver on earth.

No one likes to think this but it’s very possible voyager is the farthest humanity will go. In fact realistically speaking it is the far more likeliest possibility.

I think only the Grand Tour program was possible every 175 years: From Wikipedia [1]: "that an alignment of Jupiter, Saturn, Uranus, and Neptune that would occur in the late 1970s would enable a single spacecraft to visit all of the outer planets by using gravity assists."

Gravity assists with more than one planet are more frequent. Cassini-Huygens [2] as example had five (Venus, Venus, Earth, Jupiter, Saturn)

I would suspect when the goal ist only to leave the solar system as fast as possible (and don't reach a specific planet) they are much more often.

[1] https://en.wikipedia.org/wiki/Grand_Tour_program [2] https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens

Not useful, because the signal are too weak to be picked up probe to probe.

On earth, the tiny signal from Voyager at this distance is picked up by dish the size of a football field; same with sending of the signal.

Well, the voyager power source is still pretty good. But as I understand it the thermocouple that converts heat to electricity has degraded. Because the Pu-238 half life is 87 years so they wouldn't even be down to half yet..

I wonder if we can go the reverse direction, where instead of launching more probes from Earth to serve as relays, the spacecraft would launch physical media toward Earth packed with whatever data it has collected. Given advancements in data storage density, we could achieve higher bandwidth than what's possible with radios.

The logistics would be difficult since it involves catch those flying media, especially if the spacecraft were ejecting them as a form of propulsion, they might not even be flying toward Earth. I was just thinking how early spy satellites would drop physical film, and maybe there are some old ideas like those that are still worth trying today.

With current probes being so "slow" (peak speed of the Voyager probes was on the order of 0.005% the speed of light) I wonder if even doing 10 probes at once per decade gets you more data back than working towards faster probe for less total time.

You could use this to create a relay in reverse order, but I also wonder if having a 50-100 year old relay would be any better than just using modern tech directly on the newest, fastest probe and then moving on to the next when there are enough improvements.

Could a probe return data by semaphore? Wave a flag that blocks the light of Alpha Centauri as seen from a telescope off to the side of the sun, say at the distance of Neptune's orbit. It should be possible to hide Alpha Centauri behind a relatively small semaphore until the probe gets fairly close.

My intuition is that the extra mass for the receivers would be a large negative in terms of travel time (1/sqrt(m) penalty assuming you can give each probe fixed kinetic energy).

Plus keeping a probe as active part of a relay is a major power drain, since it will have to be active for a substantial percentage of the whole multi-decade journey and there's basically no accessible energy in interstellar space.

Then again, it's still far from clear to me that sending any signal from a probe only a few grams in size can be received at Earth with any plausible receiver, lasers or not.

That's how the mongols communicated but with guys on horses.

Americium battery could last a lot longer.

This is a link budget problem. A probe has to have a certain transmit power, receive sensitivity, physical size, fuel for orientation, etc. So you have to come up with the optimums there were it makes sense at all which isn't easy, especially compared to having one big station near earth that communicates point to point with the deep space whatever.

It might just have to be much too big to be worth it in the next n centuries.

If humans settle Mars it'll probably make sense to build one there for marginal improvement and better coverage with the different orbits of Earth and Mars.

Hmm, do you realize, that even if you have 1B probes everywhere. You're still bound by speed of light communication speed, right?

It's faster than probe speed in this age, yeah. But still not enough, if we're talking distances to other specific planets, stars, etc.

Two possible ways to solve this, humans will become immortal or speed of light bypass method will be discovered.

Astronomers often have an error margin of an order of magnitude or two. 1 billion or 100 billion. Close enough either way!

Voyager 2 was the real beneficiary of the rare outer planet alignment, as it went on the famous Grand Tour, visiting all four of the giants. It did gravity assists at Jupiter, Saturn, and Uranus. [1] shows the rough velocity of V2 over time.

Voyager 1 was directed to perform a flyby of Titan, at the cost of being thrown out of the ecliptic and being unable to visit the ice giants like its sister. But this was deemed acceptable due to Titan's high science value.

[1] https://commons.wikimedia.org/wiki/File:Voyager_2_-_velocity...

Is this HN discussion about your blog post? If not, can you share it? I would like to read it.

And that love letter came with a very nice mixtape. https://en.wikipedia.org/wiki/Voyager_Golden_Record

Extended piece from my blog.

The two Voyager spacecraft are the greatest love letters humanity has ever sent into the void.

Voyager 2 actually launched first, on August 20, 1977, followed by Voyager 1 on September 5, 1977. Because Voyager 1 was on a faster, shorter trajectory (it used a rare alignment to slingshot past both Jupiter and Saturn quicker), it overtook its twin and became the farther, faster probe. As of 2025, Voyager 1 is the most distant human-made object ever, more than 24 billion kilometers away, still whispering data home at 160 bits per second.

Each spacecraft carries an identical 12-inch gold-plated copper phonograph record.

The contents:

- Greetings in 55 human languages.

- A message from UN Secretary-General at the time and one from U.S. President Jimmy Carter.

- 115 analog images encoded in the record’s grooves: how to build the stylus and play the record, the solar system’s location using 14 pulsars as galactic GPS, diagrams of human DNA, photos of a supermarket, a sunset, a fetus, people eating, licking ice cream, and dancing

The record is encased in an aluminum jacket with instructions etched on the cover: a map of the pulsars, the hydrogen atom diagram so aliens can decode the time units, and a tiny sample of uranium-238 so they can carbon-date how old the record is when they find it.

Sagan wanted the record to be a message in a bottle for a billion years. The spacecraft themselves are expected to outlive Earth. In a billion years, when the Sun swells into a red giant and maybe swallows Earth, the Voyagers will still be cruising the Milky Way, silent gold disks carrying blind, naked humans waving hello to a universe that may never wave back.

And it was Sagan who, in 1989, when Voyager 1 was already beyond Neptune and its cameras were scheduled to be turned off forever to save power, begged NASA for one last maneuver. On Valentine’s Day 1990, the spacecraft turned around, took 60 final images, and captured Earth as a single pale blue pixel floating in a scattered beam of sunlight — the photograph that gives the book its name and its soul.

It was the photograph that inspired this famous quote -

"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there-on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known. "

That picture almost didn’t happen. NASA said it was pointless, the cameras were old, the images would be useless. Sagan argued it would be the first time any human ever saw our world from outside the solar system. He won. The cameras were powered up one last time, the portrait was taken, and then they were shut down forever.

I think there are a few movies that made me realize how much the space is vast, empty and adverse to life.

I think it would be nice for people to take a look at them:

- Aniara (2018)

- High Life (2018)

and maybe in a less artistic view:

- Powers of Ten (1977) yt: https://www.youtube.com/watch?v=0fKBhvDjuy0

In my opinion, if we really want a presence off of earth we'd be better off building larger and larger space habitats and bootstrapping a mining industry in space.

Gliese 710 will pass 0.17 light years from us in a bit over 1M years. If we can colonize mars and build some infrastructure in the solar system by then, we should have an OK shot at getting something there to stay. It'll be 62 light days away.

Note that a journey to a star a 100 light years away where you accelerate and decelerate with a constant 1 g for each half of the journey only takes 9 years of subjective time for the traveller (hence the twin paradox). To Proxima Centauri (4.24 ly) the gain isn’t as dramatic, it would take 3.5 years of subjective time.

Of course, we aren’t anywhere near having the technology for that, and there may not be any suitable planets in that vicinity, but it also doesn’t seem completely impossible.

Space is cool, and I support the scientific work some of its pioneers discover. But the category of people who believe space travel is somehow the solution to problems on Earth give me headaches.

I have an optimistic view that building underground facilities on Mars/Lunar might not be a far-stretched idea. But I have never done any research into the idea so not whether it works or not.

Basically, reducing costs and tech requirements by going underground (since it is underground we do not need to terraform the planet, and it is less likely to leak oxygen to external environment). Digging dirts and stones is a solvable problem. So optimistically I believe this is just an engineering/cost problem.

Yes, the distances are mind-boggling. There are a few somewhat realistic solutions for making such a trip in the forseeable future. If you send something of significant mass, it is certain to take a long time. So we're either talking generation ships(§), embryo space colonization (growing into adults en route or at destination) or hibernation. That or a breakthrough in fundamental physics.

--

(§) Something like O'Neill cylinders with fusion as energy source could work

Proxima flares and bathes Proxima Centauri b in radiation when it does, so it seems unlikely to be particularly habitable. But it's still tantalising...

Or we learn how to make uninhabitable planets habitable. Would also help us “save” this one.

(Funny how we say “save the planet” when we really mean “save people/complex life”).

Well I guess real end of the world will come around when we crash with Andromeda.

well, that's only about 30 light-minutes left

>Site is down?

They got Slashdotted ;-)

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

Management then cared that their one chance would work. Today management just wants it to mostly work.

Incentives and goals are very different between the two. We could very much build even more incredible things today; and would argue that we actually do. Just only in the places that seem to matter enough to do that type of special effort for.

Technically when tweeted for the given selective timespan, but no longer true since the crash this year in DC.

Still, mind blowing. When fact checking this I learned we went over 2 passenger light years worth of airline travel with no fatalities during that time frame. Incredible safety record. Real shame this year has been so terrible for our reputation.

One of the neat things that I've stumbled across is https://thinkzone.wlonk.com/SS/SolarSystemModel.php

Make the model scale to be 10000000 (10 million). The sun is a chunky 139 meters in diameter. Earth is 15 km (9 miles) away. Pluto is 587 km (365 miles) away. The speed of light is 107 kph (67 mph).

Alpha Centauri is 4.1 million km (2.5 million miles) away... that is 10 times the earth moon distance.

Another comparison... Voyager 1 is moving at 30 light minutes per year. (Andromeda galaxy is approaching the Milky Way at 3.2 light hours per year)

At Voyager 1's velocity, it would take ~456 million years to reach the heart of the Milky Way (Sagittarius A*), some ~26,000 light-years away. That's roughly the same amount of time that has passed since the Ordovician–Silurian extinction, when volcanic eruptions released enough carbon dioxide to heat up the planet and deoxygenate the oceans, resulting in the asphyxiation of aquatic species (about 85% of all life was snuffed out). The oceans remained deoxygenated for more than three million years.

Less than that is you are constantly accelerating.

I believe there's a semi-common sci-fi construct to send probes containing human brain dumps running on silicon to these far away star systems. Just hit pause until a week before arrival :).

I share the sentiment but it seems a bit like imposing a human narrative on a Universe that does not seem to care all that much about us. Maybe we really are stuck in the Solar System and space is just too vast to do much about it.

That colonization was primarily driven by the need to obtain resources. Today and in the future, there is no reason to should send humans to gather resources when we can send robots to do it instead.

We know where it is right now, because we know which way it's going, how fast and that it isn't currently thrusting anywhere. its just going in a (straight?) line, so it's pretty easy to keep track of.

You can measure the speed of something towards/away from you by measuring the doppler shift of the signal (how much the frequency is increased or decreased compared to the expected frequency), and since the radio receivers will have to be very precisely pointed to get a good signal, you can also probably fine tune any estimates of position by wiggling the receivers around a little bit until you get the best signal. The signals are definitely getting degraded by noise etc, since it's so far away. That's why the communication speed is so slow, so they can make sure they got one bit before getting the next one. Some more mathsy details here https://space.stackexchange.com/questions/24338/how-to-calcu...

But by having a very big antenna, and knowing exactly what you're looking for and where, it can help to filter out all the noise and get out the proper data

Per Wikipedia:

It has a 3.7-meter (12 ft) diameter high-gain Cassegrain antenna to send and receive radio waves via the three Deep Space Network stations on the Earth. The spacecraft normally transmits data to Earth over Deep Space Network Channel 18, using a frequency of either 2.3 GHz or 8.4 GHz, while signals from Earth to Voyager are transmitted at 2.1 GHz.

For reference, the oldest cave drawings we know of were made by neanderthals around ~70,000 years ago [0].

[0] https://www.southampton.ac.uk/news/2018/02/neanderthals-art....

No, it would no reach that star. It is not aimed at it but at the constellation Ophiuchus.

Both Voyagers left the ecliptic plane with their final gravitational slingshots (Voyager 1 went north, Voyager 2 went south so only the Canberra radio dishes can communicate with it) so even when Earth is further from them than the sun there's 35 degrees of separation.

> No, not "About to". It's this time "next year".

48 years in space and a light-day from Earth? I think it qualifies for "about to" :)

(At this point 1 year is ~2% of total time in space)

I've been reading such posts for years. Every few months, "Voyager 1 is the most distant man-made object ever!" or "Voyager 1 about to leave the Solar System!"

Well duh!

This question is the premise of Far Centaurus by A. E. van Vogt [1].

[1] https://en.wikipedia.org/wiki/Far_Centaurus

Once we develop more efficient propulsion (fission, fusion, light sails, etc.), would you like for someone to catch the Voyagers and bring them back into a museum? I myself am not sure. (Perhaps a "live museum" instead, keep them on their trajectories, but surround with a big space habitat with visitor center and whatnot.)

Physics are not so bad for interstellar travel.

We just need a an engine that accelerates our space ships with 1g constantly. With that, we would reach something like 80% lightspeed after one year. Exactly in the middle between start and destination, we would turn the ship around and start accelerating towards earth again.

A trip to Alpha Centauri could be done in less than 4 years ship-time. Earth-time would be some years longer.

1g constant acceleration would be quite comfy for humans.

The only thing we need for this plan is the constantly running engine. I propose to bend space-time in front (or behind) the ship, for it to keep falling forwards.

If we don't wipe ourselves out in the next 1000 years, I think we'll launch manned missions to other star systems that make it to their destination hundreds and even thousands of years into the future, with their original crew still alive.

Haha, never doubt science! You never know. Centuries ago, humans then would have regarded today's technological feats as impossible.

But, yeah, I don't think we are ever leaving the Milky Way. Lol

Unless we go extinct, I would assume eventually it will happen. Maybe in tens of thousands of years.

I love how 3 years/second seems slow at this time scale.

> With time dilation, the "now" on Voyager is out of sync with our now

A couple minutes [1].

> we will have to face the problem of time keeping across the galaxy

Not really. Barring relativistic travel, it’s not dissimilar from the problem seagoing voyagers faced on long trade routes. Ship time is set based on the convenience of the passengers and the route.

[1] https://space.stackexchange.com/questions/56055/if-voyager-1...

Yes, we fully realized the lessons and have stopped wasteful fighting and overconsumption and have embraced a cohesive, sustainable lifestyle to protect the only life we know of in the universe. It is wonderful.

It has always surprised me that this is the lesson so many people see in that photo.

The lesson I see is that absolutely nothing humans do (including “wasteful fighting” and “over-consumption”) matters at all. We could colonize the solar system, or we could die out, and the Pale Blue Dot would remain the same either way.

It seems to me that people are desperately trying to squeeze a distorted message of hope from an image that fundamentally signifies the exact opposite of hope, namely indifference.

You might need to increase your connection timeout to at least 172800 seconds.

Cannot send email to recipients more than 1 light-day away

This old video is a beautiful and astounding demonstration of just how vastly, hugely, mind-bogglingly big the Universe is, and where in all this endless space our dear favourite little Pale Blue Dot (Earth) resides:

https://m.youtube.com/watch?v=X-3Oq_82XNA

We all Earthlings are extremely lucky to be alive and thriving (or trying to) in such a beautiful bountiful rarest-of-rare ecosystem that somehow survived and thrived despite all the vagaries and vastness of spacetime.

Voyager’s record time in space will actually be broken tomorrow.

V'ger, was looking for a Star Trek reference and HN delivered.

Carl Sagan's reflection on the Pale Blue Dot( https://en.wikipedia.org/wiki/Pale_Blue_Dot ) image seem relevant:

"From this distant vantage point, the Earth might not seem of any particular interest. But for us, it's different. Consider again that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar", every "supreme leader", every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam. "

Nah, the whole second-Earth, terraforming nonsense is pure rationalization for whatever they want to do. If they weren’t using that as a post hoc justification, they’d just land on something else.

It gets even better when you think about all the damage we've done in ~200 years of industrial revolution.

We can't keep our perfect home in working order after so little time but they believe we'll transform dead rocks with no atmospheres in paradise...

Nuclear propulsion is the answer to this problem, but we're too busy with internal affairs to get around to trying it.

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

The way I see it, it takes a very selfish person to be a billionaire in the first place— one that not only doesn't care about people today, but also doesn't care about future generations of humans, let alone other living beings.

Any billionaire pointing at space exploration as humanity's salvation is, IMO, either really just craving the attention and glory of conquest (much like Caesar, Napoleon, Alexander, etc) or seeking the conditions of the age of exploration (XV to XIX centuries), when companies were as powerful as governments and expansionism was unfettered.

They're not going to be alive in 100 years (barring AGI intervention), so why would they care?

You people should stop demonizing billionaires. You're the ones burning the fossil fuels, not them. If their wealth way distributed among more people then those people would spend it damaging the environment which is what people generally do with their money anyway.

This is not an example of nor even an attempt at long horizon thinking. Voyager wasn't built with the intention that it would last for decades. It was a rush job to take advantage of a very rare planetary alignment and it's primary mission was completed 12 years after it started.

It is a testament to the ingenuity of the engineers who have worked and are still working on the project that they've managed to keep it to some degree functioning for so much longer than it was intended to last.

Agree. Voyager is probably considered by many to be one of our greatest achievements.

It makes me wonder when we'll have anything set foot in another star system. I would guess realistically after 2100, but then we went from the Wright brothers to landing on the moon in under 70 years... so I may be proven wrong.

But the thing is, the Voyager project came about in a much more stable period for the US - and in a more optimistic cultural climate (we could say similar for the Apollo project which wasn't that much earlier). When we used to prioritize spending on basic science and projects like this that basically had no ROI (NASA didn't even much think in those terms back in the 70s). Now we're in a very different place where, in the US anyway, we're very pessimistic about the future. To create a Voyager project you have to have some hope, like you said "with the assumption that that future would exist and might care" - now we're in a very different place where people don't have a lot of hope about the future. And it's also different in that we now ask "what's the payback going to be?" - everything now seems to need to pay it's way.

Not saying that other countries won't be able to do stuff like this - probably China is going to take the position that the US used to hold for this kind of exploration. It seems to be a more optimistic culture at this point, but hard to say how long that lasts.

I like to think the Plumbob bore cap overtook Voyager 1 quite some time ago.

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

It was a unique period of interplanetary space travel where most projects were simple flybys - the first time for each planet. Because the goal was just to flyby, the secondary benefit is that the trajectory sends it outside the solar system.

Nowadays, most missions involve insertions into orbit around the target planet, therefore no secondary opportunity to send it outside the solar system. The notable exception is New Horizons, which was a Pluto flyby and will also eventually leave the solar system.

The feat, from the perspective you describe, isn't that remarkable. Humanity has tons of projects that meet these exact standards throughout our history:

> We built something meant to work for decades, knowing the people who launched it would never see the end of the story.

> We pointed a metal box into the dark with the assumption that the future would exist and might care.

> It’s proof that humans will build absurdly long-horizon projects anyway, even when the ROI is almost entirely knowledge and perspective.

The pyramids, the Bible, governments, or even businesses [0] are all human constructs that last way beyond their creators (and their intention), with and without their creator's intention.

> we ever build a civilization stable enough to think in centuries without collapsing every few decades.

This is a valid point though

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

The Voyager project itself has long ended and it's just cute to keep monitoring it and getting data from it. If nothing else, it serves well as a perpetual PR vehicle for NASA. The core of the project I would not say represents long-term thinking of NASA or civilization. I'm not convinced that we're biologically wired to think long-term. It's extremely rare when someone pops up, and they usually end up becoming extremely impactful in society (Lincoln; Jobs; Elon)

This is a strange comment. The author claims to be a human—"what we've done", "we built something", "we pointed a metal box into the dark"—but nearly every sentence sounds distinctly AI-writen.

(Examples: "I keep coming back to this:", "Voyager isn't ... It's ...", "the assumption that the future would exist and might care", "on our doorstep", "see the end of the story", "depends less on ... and more on ...", etc.)

> It’s proof that humans will build absurdly long-horizon projects anyway

They used to. But these days the people who control the economy and funding for things like this are either politicians interested in 4 year cycles or VCs interested in 5-10 year cycles.

Nobody gives a damn about long horizon stuff anymore. We landed humans on the moon half a century ago, and we still haven't reached Mars. Instead we're building some stupid apps for people who are forced to work 7 days a week in the office on some boring ads optimization algorithm to have someone to walk their dog for them and deliver their groceries for them and monitor their health because they can't get enough exercise (that would solve their health problem the way the body intended) and don't get time to leave the confines of their <strike>jail</strike> office.

That plate with info about us, where to find us... not smart, naive. I get that 70s were probably way more enthusiastic and open minded re space space exploration compared to rather bleak times now when greed often takes prime and Star Trek TOS probably had its effect too, but next time we should do better.

Dark forest theory sounds more rational conclusion on long enough timescale than Star trekkish utopias. Although, in next million years, if intercepted it should be trivial to pinpoint where it came from just from trajectory.

I'm kind of upset that we haven't done much on the equivalent level in the time since... sure we have done some very cool things, but none of it quite feels like it's on the Voyager level of duration

U made me cry on HN

When I was around five years old, I was surprised to learn that all of our tax dollars weren't going to space exploration. For some reason, I intuited that was man's highest aspiration and we'd be throwing everything at it. Come to find it's all defense spending and printing money.