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.
But we already understand the physics and feasibility of "slow" (single-digit fractions of c) interstellar propulsion systems. Nuclear pulse propulsion and fission fragment rockets require no new physics or exotic engineering leaps and could propel a probe to the stars, if one was so inclined. Fusion rockets would do a bit better, although we'd have to crack the fusion problem first. These sorts of things are well out of today's technology, but it's not unforeseeable in a few centuries. You could likewise imagine a generation ship a few centuries after that powered by similar technology.
The prerequisite for interstellar exploration is a substantial exploitation of our solar system's resources: terraform Mars, strip mine the asteroid belt, build giant space habitats like O'Neill cylinders. But if we ever get to that point - and I think it's reasonable to think we will, given enough time - an interstellar mission becomes the logical next step.
Will we ever get to the point where traveling between the stars is commonplace? No, I doubt it. But we may get to the point where once-in-a-century colonization missions are possible, and if that starts, there's no limit to humanity colonizing the Milky Way given a few million years.
It's easy until you try to actually build the damn thing. Then you discover it's not easy at all, and there's actually quite a bit of new physics required.
It's not New Physics™ in the warp drive and wormhole sense, but any practical interstellar design is going to need some wild and extreme advances in materials science and manufacturing, never mind politics, psychology, and the design of stable life support ecologies.
The same applies to the rest. Napkin sketches and attractive vintage art from the 70s are a long way from a practical design.
We've all been brainwashed by Hollywood. Unfortunately CGI and balsa models are not reality. Building very large objects that don't deform and break under extremes of radiation, temperature changes, and all kinds of physical stresses is not remotely trivial. And we are nowhere close to approaching it.
The engineering problem is insurmountable today. But there doesn't seem to be any reason it couldn't be done eventually, given our technological trajectory, unless we believe we are truly on the precipice of severe diminishing returns in most science and engineering fields, and I just don't see that right now.
George Cayley figured out how to build an airplane in 1799, but it wasn't for another century until materials science and high power-to-weight ratio engines made the Wright Flyer possible.
There are plenty of depths to plumb in space systems engineering that we haven't even really had a proper look at yet. A Mars mission with chemical propulsion is hard, but could be made substantially easier with nuclear thermal propulsion - something we know should work, given the successful test fires on the NERVA program back in the 60s. First stage reusability was fantasy 15 years ago, today it's routine.
Obviously, I'm extrapolating a long way out, and maybe at some point we'll run against an unexpected wall. But we'll never know until we get there.
GP has set the 'low bar' of providing a material that survives a series of nuclear blasts whilst generating useful thrust. I'm not qualified to judge whether or not that requires new physics but it seems to me that if we had such a material that we'd be using it for all kinds of applications. Instead, we rely on the physical properties of the materials we already know in configurations that do not lend themselves to the kind of use that you describe.
That's the difference between science and science fiction, it is easy to write something along those lines and go 'wouldn't it be nice if we had X?'. But if 'X' requires new physics then you've just crossed over into fantasy land and then further discussion is pointless until you show the material or a path to get to the material.
See also: space elevators, ringworlds, dyson spheres etc. Ideas are easy. Implementation is hard.
A more pragmatic me would point out that the required energy and materials needed would mean we would need breakthroughs in space-based solar capture and mining, but this is still not New Physics.
I think the solution will come from exponentially advancing self-assembling machines in space. These can start small and, given the diminishing cost of getting things to space, some early iterations of the first generation could be mere decades away. There are several interesting avenues for self-assembling machines that are way past napkin-sketch phase. Solar arrays are getting bigger and we have already retrieved the first material from an asteroid.
The quality and reliability of AI agents for processes orchestration and technical reflection is now at a stage where it can begin to self-optimise, so even without (EDIT) a "take-off" scenario, these machines can massively outperform people in manufacturing orchestration, and I would say we are only some years from having tools that are good enough for much larger scale (i.e. planetary) operations.
Putting humans there is a whole other story. We are so fragile and evolved to live on Earth. Unsurprisingly, this biological tether doesn't get much of a look-in here. Just being on the ISS is horrible for a person's physiology and, I am guessing there would be a whole host of space sicknesses that would set in after a few years up there or elsewhere. Unless we find a way to modify our biology enough so we can continually tolerate or cure these ailments, and develop cryo-sleep, we're probably staying local - both of these are much more speculative that everything above, as far as i can tell.
Humans evolved to live on earth. Our bodies fare poorly in low gravity, not to mention vacuum. Given sufficiently advanced technology, I'm pretty sure we could evolve some form of intelligence better suited to the environment.
The universe really doesn't want ChatGPT!
It is fair to say, that given space travel tech improves slowly relative to AI, but the distance to be travelled is so great that any rocketry (or other means) improvements will quickly pass previous launches, the first intelligence from Earth that makes it to another system will be superintelligence many orders of magnitude smarter than we can probably imagine.
It would work better for smaller, unmanned craft, especially when you consider g force limitations
NPP is only theoretical, and still has major problems such as finding a material that can withstand a nuclear detonation at point blank range. Mass drivers have been proven to work, albeit at a smaller scale
Of course, depending on how much oil you consume for each shot, you will degrade your effective specific impulse - I'm not sure by how much though.
The other issue which you can't really get around is thermal, that plate is going to get hot so you'll have to give it time to radiate heat away between shots. This may be less of a concern for an interstellar Orion since the travel times are so long anyway, low average thrust may not matter too much.
Why Antimatter Engines Could Launch In Your Lifetime https://youtu.be/eA4X9P98ess (3 weeks ago) ... with that T-shirt. ... and the bit about theoretically possible warp drives (4 years ago) https://youtu.be/Vk5bxHetL4s
The furthest a human has been is 250k miles (far side of the moon). The fastest a human has traveled is only 0.0037% the speed of light.
The ISS is about 260 miles from the Earth. At that height, the gravity is actually roughly the same as on the surface, it's only because it is in constant freefall that you experience weightlessness on it.
Mars is 140 million miles away. And not exactly hospitable.
I like how you treat "the fusion problem" with a throwaway, "Yeah, we'd have to solve that" as if we just haven't sufficiently applied ourselves yet.
All of those incredibly difficult things we have not even begun to do are the technical reasons we have not gone interstellar and may be the reason we will never do so.
And even if we solve the issue of accelerating a human being to acceptable speeds to reach another star, the next closest star is 4 light years away. That means light takes 4 years to reach. Even if you could average half the speed of light, that's 8 years, one way. Anything you send is gone.
These enabling technologies are very, very hard. No doubt about it. That's why we can't do this today, or even a century from now.
But the physics show it's possible and suggest a natural evolution of capabilities to get there. We are a curious species that is never happy to keep our present station in life and always pushes our limits. If colonizing the solar system is technically possible, we'll do it, sooner or later, even if it takes hundreds or even thousands of years to get there.
> I like how you treat "the fusion problem" with a throwaway, "Yeah, we'd have to solve that" as if we just haven't sufficiently applied ourselves yet.
If you'd read my comment, you'd see I didn't say that. Fusion rockets would help, but we don't need them. Nuclear pulse propulsion or fission fragment rockets could conceivably get us to the 0.01-0.05c range, and the physics is well understood.
> And even if we solve the issue of accelerating a human being to acceptable speeds to reach another star, the next closest star is 4 light years away. That means light takes 4 years to reach. Even if you could average half the speed of light, that's 8 years, one way. Anything you send is gone.
Getting to 0.5c is essentially impossible without antimatter, and we have no idea how to make it in any useful quantity. Realistically, we're going there at less than 0.1c, probably less then 0.05c. Nobody who leaves is ever coming back, and barring huge leaps in life sciences, they probably aren't going to be alive at the destination either. It'd be robotic probes and subsequent generation ships to establish colonies. But if you get to the point where you are turning the asteroid belt into O'Neill cylinders, a multi-century generation ship starts to sound feasible.
You are talking about massive investments to shoot off into space never to return. Who's paying for that? The only way you do that is if you're so fucked, it's your only option and the profit in it is the leaving.
Not to mention, we need to solve the problems of living in space. Which we haven't yet. According to NASA. The space people.
And it very well could be an insurmountable problem. We do not know. We do know that living in microgravity fucks you up. We know that radiation fucks you up. But we don't even know all the types of radiation one might encounter.
> But if you get to the point where you are turning the asteroid belt into O'Neill cylinders
That right there is an example of "solve this impossibly hard problem and the rest is easy". We are nowhere near doing anything close to that.
What if there was a faith system of ultimatley going to interstellar medium. You have faith, you automatically pay, like the rest of the people and you dont question it. You get tax breaks. It will help you in the end of times or something.
Just decide the ultimate goal to be interstellar medium touching in all directions.
You are a farmer? Well now you continue to farm to feed budding spacers. You are a game dev? Well, people are going to get bored in space, continue developing games for the ultimate goal.
The human compatibility issues with microgravity are well known, as is the solution, which has even been proposed by NASA: centripetal force to create 1G for the astronauts.
As far the the radiation goes, we do indeed know exactly what kinds of radiation they would encounter. And the easiest way to shield humans from it in space is lots of water, or metal. We know this from extensive real work done on earth re: nuclear power plants.
The real issue is money, not technical feasibility. Once the dough rolls in from asteroid mining, it bootstraps the financing issue and pays for itself many times over.
NASA seems less sure than you do. And considering we have to get to the asteroids before we even start to think about mining them, talking about the money from asteroid mining is putting the cart before the horse.
If we do ever reach that distance again it will be even less likely we do it for a third time.
Absent a general decline in the capacity of our civilization the main hurdle I see is that the cost is paid by people who will not live to see the results of it but I don't think that rules it out, I'd certainly contribute to something like that.
What are some of the other factors you are thinking of?
It's not pessimism, it's reality. Think about how unlikely it is. Humanity had one stretch where we reached for the stars and that stretch ended and by sheer luck some crazy guy made it cheap. What happens when he's gone? Will it happen again? Most likely: no. In your lifetime? Even Less likely.
There was simply no incentive to do so yet. But one day we will build faster spacecrafts and then we are going to overtake it quite quickly.
I certainly wouldn't bet against technological progress, and I say that as a complete doomer.
A flyby of both Jupiter and Saturn can be done every two decades or so (the synodic period is 19.6 years)
New Horizons (which has the distinguishing feature of being the fastest human-made object ever launched from earth https://www.scientificamerican.com/blog/life-unbounded/the-f... ) is traveling at 12.6 km/s.
The key part there is that it got multiple gravity assists as part of the Grand Tour https://en.wikipedia.org/wiki/Grand_Tour_program . You can see the heliocentric velocity https://space.stackexchange.com/questions/10346/why-did-voya... https://www.americanscientist.org/article/the-voyagers-odyss...
The conjunction for the Grand Tour is once every 175 years. While you might be able to get a Jupiter and Saturn assist sooner, it is something that would take the right alignment and a mission to study the outer planets (rather than getting captured by Jupiter or Saturn for study of those planets and their moons).
While I would love to see a FOCAL mission https://en.wikipedia.org/wiki/FOCAL_(spacecraft) which would have reason for such a path, I doubt any such telescope would launched... this century.
That alignment will happen many more times in the history of humanity. That is to say, I don't know if a spacecraft to overtake Voyager will be launched on the next alignment or one 10,000 years from now, but it doesn't seem unlikely to happen.
Once we leave the solar system in a self sufficient way I can’t see any event which would cause a species level extinction
And we would have to establish the reason for the colony … I’m not talking about a research base, but a place where people would settle, do useful ecomonic activity, raise families and live out most of their lives … I cannot 5hink of a reason why people would want to do 5hat anywhere but Earth.
Interstellar travel is a physics problem, not an engineering one. Even make believe nuclear propulsion is still aggressively limited by the rocket equation and still wont get you anywhere in a meaningful time frame.
There will never be an interstellar empire. It will never make sense to do trade between two planets that are otherwise capable of producing things, because the energy cost of doing anything in space absolutely dwarfs any possible industrial process. It doesn't matter how low quality your local iron ore is, importing ore from a different planet will never be a better option because transportation costs are effectively infinite.
Human trade is almost entirely based on the fun quirk that sea based transportation is ludicrously efficient, such that you can ship a single pound of product all over the globe and it can still be cheap. The physics of space are essentially the opposite of the physics of sea travel, in that it is dramatically harder and more energetically expensive than almost anything else you can do, and the energy regime it operates in will dwarf any other consideration.
If there was a magical way to turn joules directly into a change in kinetic energy, as in a machine that could magically extract every joule of "energy" from matter in an E=mc^2 way and directly reduce an object's kinetic energy by that much, taking a 100 kilogram human up to half the speed of light and eventually slowing them down again would take 31 kilograms of matter to "burn", and you have to accelerate all that matter too. That matter would require another like 10kg of matter to "burn" and then you have to accelerate that matter too and so on and so on.
And we do not come even remotely close to any mechanism, real or theoretical, that could convert mass to a change in kinetic energy. Even if you had like a magic antimatter machine that could come very close to turning a gram of matter into it's entire "energy" content, ways of turning thermal or electrical energy into thrust have their own inefficiencies, difficulties, and do not even come close to mapping to "Each joule of energy equals a joule of kinetic energy change".
And even with our magic spacecraft machine that cheats physics, that's still an 8 year round trip to Alpha Centauri and back, with something like a 50%-65% payload fraction.
The scale of things in space combined with the nature of that space makes interstellar anything nonsensical. Even interstellar travel of just information is fairly mediocre. SciFi will never exist in our world, and at this point should probably just be called "Fantasy with more plastic"
IE either what speed Voyager 1 launched at excluding the gravity assists, or what speed New Horizons would have reached if it were launched 175 years after Voyager 1 (to take advantage of the same gravity assists)?
Another part in this is the "the probes are slowing down over time" - and you can see that with the Voyager 1 data that while the velocity after assist is higher than before, its not a line at slope 0 but rather a curve that is slowly going down.
This is further complicated because New Horizons had a launch mass of 478 kg and voyager was a twice as massive at 815 kg.
They also had different mission profiles (Could Voyager 2 taken a redirect from Neptune to Pluto? That trajectory change would have required a perigee inside the radius of Neptune...)
Voyager was done with a Titan III-Centaur rocket (that had a misfire) https://en.wikipedia.org/wiki/Titan_IIIE
> Voyager 1's launch almost failed because Titan's second stage shut down too early, leaving 1,200 pounds (540 kg) of propellant unburned. To compensate, the Centaur's on-board computers ordered a burn that was far longer than planned. At cutoff, the Centaur was only 3.4 seconds from propellant exhaustion. If the same failure had occurred during Voyager 2's launch a few weeks earlier, the Centaur would have run out of propellant before the probe reached the correct trajectory. Jupiter was in a more favorable position vis-à-vis Earth during the launch of Voyager 1 than during the launch of Voyager 2.
Note also in there that a few weeks difference between Voyager 1 and Voyager 2 had different delta V profiles (which is why Voyager 1 is faster)
New Horizons was done with an Atlas https://en.wikipedia.org/wiki/Atlas_V
... and I don't have enough KSP background to do the orbital mechanics for this.
Its not "interstellar speeds" but I'm pretty sure we could get probes further out than Voyager 1 faster if we put the money behind it.
Currently though there’s nothing planned to leave the solar system faster than voyager 1. New horizons will never catch up short of some weird gravity slingshot in millions of years which is probably just as likely to fling musks roadster out into interstellar space
What insight do you have into this issue that would suggest this is true?
... Be responsible for the very longterm torture of billions of intelligent lifeforms who are forced to drift through boring space for 1000s of years.
If we launched today, 1% faster would be enough.
If we launched in a hundred years, 1% faster would be enough.
And going faster is downright easy. We can beat Voyager's speed significantly any time we want (plus or minus ten years for planetary alignment).
We haven’t even set another foot on the moon during my lifetime, and we’re not factually any closer to doing so. We have allowed a military industrial complex to keep making money by over-designing and under-delivering over and over and over for a population with constantly dwindling wherewithal, resources, and attention span.
I am neither an optimist nor a pessimist, I am a realist… and the real odds decrease with every passing moment.
The odds we could surpass Voyager aren’t shrinking, the odds we will are.
To me it seems like the odds are close enough to 100 that it's hard to claim a trend. If you asked me mid cold war I might have said there's significant risk we all die first, but not so much now.
Also don’t know how you’ve missed it, but we’re actually in a more globally precarious position today than we were during the vast majority of the Cold War. But let’s see where we are in 2030.