The winning proposal coasts at 0.01c. Propulsion systems--not the speed of light--and thus engineering, not phsyics, are the relevant limitors.
Cathedrals were built over 100s of years. Imaging just living in a massive one and your whole holy purpose is to survive and thrive and spread.
It's entirely reasonable we'd have the will to make it happen, and pretty reasonable we'd be able to build it with planet scale effort, but sadly quite difficult to imagine it surviving even dust impacts for 400 years.
Whipple shields [1].
Vs
> 0.1c
Off by quite a bit
Up to 0.1c is from the interstellar spaceship competition "cruise" speeds (also used 0.01c) as presented in their deck.
They're a few orders of magnitude difference.
Also, there's plenty of resources around on interstellar travel that shows interstellar dust/debris is going to be a huge problem.
For example Atomic Rockets, which has a bunch of good reference materials (albeit poorly organized), or the Astronomy Cafe
https://sten.astronomycafe.net/at-what-speed-does-the-inters...
Everything is consumed on such a voyage. If we can send a generation ship at 0.01c, we can send replacement parts quicker and probes ahead to verify our estimates even faster.
There's no free lunch. Every gram of mass that you want to get to interstellar space requires exactly as much fuel to get there as you'd have to add to the original spacecraft to just carry it.
(thought experiment - have them fly side by side, then connect them by string, then shorten the string until they touch, then weld them together - the fuel required doesn't change at any point).
And a shield + a resupply ship has a lot more grams than just adding the shield to the original thing.
"We" are not even able to sustainably inhabit our current planet. We have hundreds of millions starving every day, we have wars in many places, the threat of thermonuclear war looming as strong as ever, and are still using natural resources at an unsustainable rate even though we know that that's the case. Settling on other planets has all these problems plus the issue of getting there plus the issue that the environment you find there is more hostile than the most hostile desert areas here on earth.
We currently live on paradise planet and can't even make things work well around here. Hard to see how you could make things work on Mars where you can't just go outside pick a leaf to eat and get some water to drink. Or just, you know, breathe.
It's fine if you believe we should not go (but I disagree), but the state of the world is not evidence of failure of the mission.
Then maybe it's time you stop being ignorant. It's not even hard to google. Start with the WHO, over 700 million people faced hunger and malnutrition in 2023. [1] And I'm not particularly interested in how you will try to nitpick your way out of that. It's so easy in the west and in upper classes of the developing world to close your eyes to this.
[1] https://www.who.int/news/item/24-07-2024-hunger-numbers-stub...
> And if we did, we don't have a large portion of industrialized/militarized missions starving every day anway. We'd send the best of the best, hand picked, with the best tech we can build.
Initially, sure. But that's not what I was talking about. Eventually you want to build a civilization there, right? Eventually you have millions there. And it's hard to see how you will be able to organize a society in large scale in a way that does not have the problems humankind currently has if you can't even fix that here which compared to all other planets is a nature paradise. Even after a thermonuclear war, earth is easier to live on than any other planet in this solar system. Time to leave your scifi bubble if you believe otherwise.
> It's fine if you believe we should not go (but I disagree), but the state of the world is not evidence of failure of the mission.
The state of the world is evidence of failure of a mission that is much easier than building a civilization on another planet.
> your whole holy purpose is to survive and thrive and spread.
Go forth, and multiply.
“The indefatigable spirit of exploration” isn’t the answer. People, as a mass, only explore to find new resources due to scarcity.
There are exceptions, but they tend to be thrill seekers or publicity hounds seeking to capitalize on a measure of fame upon their return and dying on a spacecraft 1/5th of the way through its journey isn’t thrilling and no ticker tape parades await your return.
If you can build a spacecraft capable of sustaining 1,000 human lives for multiple centuries, you’ve solved all local resource scarcity problems. You could just mine the solar system and build billions of habitats that lazily circle the sun.
Hell, you wouldn’t even care about habitable planets anymore and a likely endpoint for any interstellar efforts would likely be a long-lived star with large orbiting gas giants you could turn into solid materials in order to build trillions of habitats orbiting that star, not an insignificant earth-like boulder.
Imagine turning all of the methane in a gas giant into carbon strands, using its hydrogen to do it and building a near-infinite number of habitats, each perfectly suited to human existence.
An earth-like planet with its quakes and tsunamis and seasonal cycles would seem pathetic.
Empirically totally untrue as to be trivially disproven by like half of wealthy social media.
> thrill seekers or publicity hounds seeking to capitalize on a measure of fame upon their return
Everyone on these ships would be a celebrity on Earth. (Ideally, if they so chose.)
Again, a simple reading of one-way trip settler-explorers across history similarly rejects this notion.
> If you can build a spacecraft capable of sustaining 1,000 human lives for multiple centuries, you’ve solved all local resource scarcity problems
The first several of these ships are likely to end in catastrophe. The first to succeed will be breaking down on arrival. If we learn to build luxurious space habitats it will be through these endeavours.
A week in Bali is not the same thing as interstellar travel…
Are you genuinely unfamiliar with the folks who launch off on their own into the deep wilderness for years on end. Not only for vanity, but largely to do groundbreaking research?
Are you confusing "adventurer" and "explorer"? There are plenty of contemporary adventurers (motivated by ego, fame, personal achievement) but explorers? Not so much.
Anywhere that might sustain life is no closer than a couple thousand years away if we develop ultra-efficient almost magical engines that only bend the laws of physics instead of breaking them outright. Stuff like accelerating the propellent so hard that it picks up enormous amounts of relativistic mass, like every gram of propellant weighs effectively a ton because you've accelerated it so close to the speed of light, which requires some kind of ultra-dense power source that makes mere matter-antimatter annihilation look like burning a match.
We'd have to completely re-think industrial processes. I'm in favor of realized nanotechnology and 3d printers at an atomic level. Evolution stumbled across carbon based lifeforms as it's answer on Earth.
Isn’t this impossible? Doesn’t entropy preclude perfect ongoing repair?
Yes, but we don't actually need "perfect". Also: you can counter a lot of entropy from the energy supply of those engines.
Counter-but: we aren't even close to good enough for what we do need.
Why? If we can accelerate a small city to 0.01g in a year, we can accelerate smaller packages to catch up with it once a year.
The beauty of this setup is that if you are really good at keeping the schedule, this can be all pre-computed. With time slots being allocated beforehand when the laser arrays send beams in a given direction & the packages (or the craft itself) just making really sure they stay in the beam & properly oriented when it arrives at the planed place and time.
With exponential growth and the second law of thermodynamics, there’s no such thing as solving resource scarcity, only delaying it.
We couldn't even reliably get people to put a piece of fabric over their face to stop killing their own relatives. Even if we could build a generation ship, it would turn into an Event Horizon hellscape if we don't figure out better cultural, communication, and sociological tools to enable us to get along and work together effectively.
Rural Americans couldn’t. But I don’t see anyone proposing we put high school dropouts and polio patients in space.
China, India and Japan managed to pass that test just fine. I imagine one of the former two will be the first to colonise deep space.
> Rural Americans > high school dropouts
Lol HN you really are too much sometimes.
Covid went really well in all the intellectual bastions of liberal democracy right? NYC, SF? California famously no downsides from their policy choices at all.
And then to top it off, you compare response to China - the government that lied through it's teeth about covid from the beginning, jailed journalists and destroyed evidence.
Unreal
New York is a bad example to call out since it was one of the first places to get hit, locked down hard after a delay, and yet came out with lower per-capita deaths and a stronger economy than most red states. (Speaking as someone who lives in one of the reddest states in the union.)
> jailed journalists and destroyed evidence
Not sure we can call anyone out on this anymore.
The question is "Could we create a cadre of 400 highly effective people that could sustain a colony on a spaceship.
I argue the answer to the first is "No" for any demographic but the answer to the second is a clear "Yes".
For a generational ship, the question becomes even more complex because you would have to build a culture of expertise that can sustain itself over multiple generations.
COVID didn't test for capacity to sacrifice for the common good. Sacrifice is voluntary. It tested for capacity to submit to authoritarian control for the common good.
Still not sold though that the cohesion in an small, resource constrained, artificial community can hold over a few generations. Huge risks of it degrading into some cult/dictatorship.
This is not to say that generation ship societies are doomed to fail but chances are decent.
One of the primary causes of our cultural disfunction is our seemingly intrinsic compulsion to separate ourselves into groups of Us and Them, and have no limit to the amount of disparaging, scorn, and dehumanization we are willing to dump onto Them.
>Limiting Factor
I see what you did here.
If you entered a bus or any public space during that time, most people were wearing masks. And bus schedules were heavily adjusted to decrease density of people. Society did a lot to fight the virus, just not based on mandates but based on getting people to voluntarily do what was necessary because they in majority used common sense and an undertanding of what's the danger and what is needed. Similar to what an intergenerational space ship would need.
So, if your argument is "you can solve big problems without coersion" then I'm with you. You need a high trust society.
Though if your argument is "the mask stuff was just BS, just look at Sweden, they didn't use any and turned out well" then you just don't have a clue what you are talking about.
Most people used mask, even in the street, nobody complained, but a few morons used it in the chin that is not very effective.
Anyway, we got more death per million than Sweden.
We're never leaving because "woke."
/s
My guess is that we will colonize the asteroid belt (Palladium! So much palladium!) and send lots of interstellar probes long before we try to send humans outside the solar system. Right now we're like a village that lives by a river and has never reached the mouth talking about sailing across the ocean. There are a lot of intermediate stages.
The book Delta V [1] explores that scenario, with an asteroid on an orbit close to Earth to minimize the delta v to ship things back home.
And that’s an enormous understatement. Let’s say the villagers have travelled a meager 10 km of the river. Then, the ocean is, ballpark, at most 1,000 times as wide as the distance to the sea.
A thousand times the distance between earth and moon (the farthest humans have travelled) gets you, ballpark, to mars.
A lightyear is ~50,000 times the distance to mars or 50,000,000 times as far as humans have travelled. And yet, in interstellar travel, a lightyear gets you nowhere.
Which is wrong. Direct-drive fusion fits the bill. It’s also easier than terrestrial power-generating fusion since you don’t need to convert to electricity.
Then double that to slow down. And remember efficiency and that well you need to spend some to keep people alive...
Seems like energy in general is one of the true problems.
This math is wrong.
Back of the envelope: accelerating 250 x 10^6 kg to 1% of c over one year is about 310,000 TWh. That’s like half of current annual energy production.
Even at like 10g, which would accelerate that mass to 1% c in less than half a day, you’d only use like a tenth of our 10^22 joules of fossil fuel reserves.
> double that to slow down
Why the asymmetry? 1x to accelerate, 1x to decelerate. (Less if you can aerobrake and/or use gravity assists.)
Taking the 310k TWh from earlier and doubling it, and assuming 18 MeV for D-T direct-drive fusion, and you need 6,600 kg fuel for the journey. (Plus propellant.) 100x that to account for inefficiency and cooling and you have 660 metric tonnes of hydrogen. That, if kept in its bastard liquid form, takes up about 3 Olympic-size swimming pools in volume.
Shame we don't have a way to efficiently convert fuel energy directly into a ship's kinetic energy, and have to go via conservation of momentum… though I suppose magnetic launch of interstellar vehicles would be a neat use for a Dyson shell or Niven ring?: https://www.wolframalpha.com/input?i=0.5+*+1+gee+*+%280.01c%...
https://projectrho.com/public_html/rocket/
It's _full_ of good stuff.
Still, even half of current annual production is quite a ask. For single ship, and I might venture to guess that 250e6 kg might be light for what is needed...
I hate to be a Debbie Downer, but it's kinda boring out there. We'd certainly not want to make the trek until the robots had scoured the galaxy looking for a fun place to visit. And by that time we'll all be living in some post-Singularity holodeck and won't give a hoot about some empty rock 600 light years away.
Send the bots. I'll watch the highlight reel from my pod.
Expansion will only go as quickly as travel time allows. Even the speed of light seems insufficient beyond a certain point. We will want to manipulate space.
An atomic (fission) Orion can achieve perhaps 9–11% of the speed of light. [...] At 0.1 c, Orion thermonuclear starships would require a flight time of at least 44 years to reach Alpha Centauri, not counting time needed to reach that speed (about 36 days at constant acceleration of 1 g or 9.8 m/s2).
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
The problem with using thermonuclear explosions to produce that level of thrust are more "but can we actually do it safely" than "but can we do it in a way that generates more that it takes to produce", but that's a not inconsiderable problem even without all the international agreements about where we shouldn't be exploding nuclear bombs...
No, we had not. That was only theoretical work, no real technology, not even a prototype.
Astronauts are extremely tough individuals.
Now, if we can figure out some form of suspended animation, that fixes many problems for long range travel.
I am much more convinced that our best way to leave our solar system will be without our physical bodies. Some form of synthetic or uploaded consciousness would be much easier to move around. After constructing a network, they could even be transmitted instead of shipped.
This is obviously in the range of science fiction but if we exist long enough, who knows.
The show, Pantheon, did a fairly decent fictional take on the idea.
You'll still need someone awake to pilot the ship, otherwise you'll end up crash landed on a planet with Riddick running loose.
[0] https://revelationspace.fandom.com/wiki/Galactic_North_(shor...
Are all of these handwaving propulsion? They seem to all be habitat designs.
Ok I'll take my shot at propulsion:
Pulse nuclear BUT:
For acceleration, we have a launch gun that fires more fuel at the ship, and the ship catches the fuel, imparting momentum from the catch, and more fuel for acceleration.
For deceleration, we have pellets that it catches up to and uses the catching to slow down with, AND gains fuel to decelerate.
If the catch can be done like an ion drive in efficiency, then you get ion drive efficiencies while gaining fuel for the pulse nuclear accelerations/decelerations.
The real problem would be timing the deceleration "catches", and a HELL of a railgun.
We aren't really doing this in current physics without a massive and functional orbital/planetary economy that gives cheap nuclear fuel and materials. We'll probably need solar wind antimatter harvesters as well, if those are actually a thing.
In your design how is it going to catch up to pellets if it's decelerating? I.e. pellets need to be pre-decelerated for this. Which raises the question, would it be cheaper just to bring all deceleration fuel onboard.
Even without taking this into account all systems are going to need active guidance - there is no way you do single burn and end up in the same place in the same time few light years away.
The best schema is probably launching all fuels containers that should be picked up for retro burn at the same time with much higher acceleration (orbital rail gun and then a burner), and with very slightly smaller final speed.
Then on the main craft you do short retro burn to match speed to fuels containers, attach them and do full retro burn for orbital insertion.
Benefit of this schema is that you don't need to accelerate everything slowly using main engine, so your original booster can be way smaller. (Energy-wise it only works if you have stationary means to accelerate high-g-capable payloads, i.e. orbital railgun, in this case you don't have to accelerate extra fuel required for initial burn)
But orion pulse nuclear propulsion is pretty powerful stuff, especially if you can antimatter-catalyze it.
Power provided by toroidal nuclear fusion reactors in the outer shell of the living module, but why do you need such reactors if your primary propulsion is provided by Helium 3 - Deuterium Direct Fusion Drive? If you have direct fusion technology, you don't need toroidal reactors.
Rotating inner shells mechanically for 400 years is terrible design, it's much easier just to rotate entire structure. Once it's going it keeps rotating inertially!
Another comment points to error in speed calculation - at declared acceleration they should go at 0.1c, not 0.01c!
And what is missing of course is the calculation of how many years of current world's GDP is required to complete such project event if all yet-to-be invented technologies exist.
Regarding the GDP needed once you have a working "mine from the moon and send to orbit" economy it doesn't seem to be too bad. The assumption would be that a lot of technology is already developed for other projects. Launching it all from earth obviously wouldn't be possible even with vastly cheaper launch. That's why they put the build into the moon-earth L1 lagrange point to be easily reachable from the moon.
For propulsion and reactors, but there are multiple projects today working on all of this. Building a life support system for 400 years is still an unsolved problem however.
Re: spin. I still claim that the best design is to rotate entire living module as one. Most of the activity is going to be on the outer shell. Warehouses, etc will be in the lower gravity inside. No moving parts.
The only question is what to do with fuel and retro engines. Rotate them as well? Fuel tanks need to be stronger. Do not rotate? Then maybe living module can undock for the flight and rotate separately.
These are supposed to be generational ships. Now imagine you need to take the primary drive down for maintenance? What does the moving colony have for power?
I'd want tri-redundant systems at a least, for everything.
My washing mashine self destructed a few times. I don't want to put my children inside one for 400 years.
I'm sure every parent has thought the opposite at least once.
I guess they were replaced a few times during the non harvesting season.
To replace the main gears of a rotating shell in space, you must "turn off" gravity for a week (or month).
But yes, it's a work of design more than a blueprint.
I hope durable file formats regain popularity before humanity starts embarking on interstellar voyages :)
https://www.canva.com/design/DAGmr3ubC8E/LHHAeeAIGGQe_TkZVs-...