I don't like the direction where mankind is going. We spend more resources to build tools which allow us to watch cat videos than on curing cancer. One day I decided to say enough, and leave this grim place.

The plan is to gather around 500 people who want to leave the planet with me, then help me to gather money, build a ship and leave. Now we don't have a goal, so our ship will be flying though space for centuries, until we find some nice suitable and friendly planet to settle down. Sounds simple, so what could possibly go wrong?

My spaceship needs to be big. It has to provide living space for my crew. I know, if you put too many people in too small a space, it creates conflict, and we don't want this in our ship. Another thing, the ship has to provide food and water for them, so we need additional space for growing plants, and probably some large storage areas for all spare parts. There are small chances we will be able to restock after we leave Earth.

Is my plan feasible? Do we have currently have tech to build that kind of ship? What will be estimated time/costs to build it? Where are the drawbacks of my plan?

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ Commented Aug 25, 2016 at 0:46
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    $\begingroup$ @MonicaCellio that was odd moving all comments, specially in the case, like this one, where they are not a chat $\endgroup$
    – MolbOrg
    Commented Aug 25, 2016 at 19:26
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    $\begingroup$ @MolbOrg The comments Monica moved had nothing to do with improving the question or asking for clarifications. They were incomplete non-answers, responses to those non-answers, poor frame challenges, recommended reading/watching for OP... chat/discussion, in other words. There's nothing in them that the question would benefit from incorporating, so they're trash. I, for one, thank Monica for doing the usually-thankless job of taking out the trash. We're not a forum. $\endgroup$
    – nitsua60
    Commented Aug 26, 2016 at 15:13
  • $\begingroup$ SyFy already tried this for us... sort of. :) $\endgroup$
    – brichins
    Commented Aug 26, 2016 at 17:00
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    $\begingroup$ "We spend more resources to build tools which allow us to watch cat videos than on curing cancer." -- so you're going to spend the money to build a rocket instead. Pure. Comic. Genious. $\endgroup$
    – riwalk
    Commented Aug 28, 2016 at 22:34

22 Answers 22


I remember a few years ago reading an article which stated that a manned trip to Mars (with return) for a couple of people could be as high as 1 trillion USD (1,000,000,000,000). This group you're supposing is several hundred times larger than the Mars trip, for several hundreds of thousand times longer trip, and they have to create a means of survival instead of supply. Even ignoring current technology and just looking at a terrible estimation of price, there's no way you're making your trip.

Let's say (again, as a terrible estimate) we'd be running a price tag of 60,000,000,000,000,000,000 USD. The GDP of planet Earth (which note, it uses the GDP to sustain itself, so we can't just yank it over to our project to fund it) is estimated at about 107 trillion USD. To clarify: Earth's GDP is not even 1% of 1% of what we're estimating for the cost.

Of course any price estimation is ludicrous since we simply don't have the technology yet to build such a massive spacecraft with such longevity and self sufficiency. Even if we had 60 quintillion dollars of 'value' (labor and supplies) we have nothing to throw it at to make this happen.

Science and engineering will have to progress significantly before we reach the proposed goal.

Sorry, Professor Farnsworth, but you'll be staying with us a bit longer.

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    $\begingroup$ Seems that if he wanted to go on this trip, he'd have to gear the entire planets economy towards scientific progress and education, thus fixing the problems that made him want to leave in the first place. $\endgroup$
    – UIDAlexD
    Commented Aug 24, 2016 at 14:09
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    $\begingroup$ could be as high as 1 trillion USD Can you please add a source about this estimation? When USA went to the Moon 50 years ago, it didn't wreck the country. I don't think that going to Mars instead of the Moon would be so expensive. $\endgroup$ Commented Aug 24, 2016 at 14:55
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    $\begingroup$ The difference being Atmosphere and Gravity. Thus Mars is ridiculously more expensive, because we're talking about coming BACK from Mars. If all you want to do is launch something into the void of space, it would actually cost significantly less than sending something to the moon. What WOULD cost more is the technology needed to sustain life infinitely on a ship. $\endgroup$ Commented Aug 24, 2016 at 15:00
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    $\begingroup$ Maybe he could make enough money by selling advertisements that are shown next to cat videos. $\endgroup$
    – null
    Commented Aug 24, 2016 at 15:26
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    $\begingroup$ @A.L The difference between the moon and mars is the difference between walking a couple blocks and swimming across the pacific. The trip time goes from one week to 1-2 years, you're subject to far more radiation for a much longer time, and unlike the moon, mars has a troublesome atmosphere. Everything has to be built tougher and last longer. Fuel cells won't cut it for a long trip - You'll need a nuclear reactor or absolutely massive solar array. Unlike Apollo you'll have to recycle everything, and your ship has to operate for the entire mission without equipment failure. $\endgroup$
    – UIDAlexD
    Commented Aug 24, 2016 at 16:04

You know, I'm kind of annoyed with these questions. Not because they are bad questions, but because people seem to forget what mankind is truly capable of when the chips are down.

Let's start with the ship needed.

First off, ship design. Yes, scale is important, but not as important as a dozen other factors. First, you need something that rotates, to help build up centrifugal force (simulating gravity). Then you need to factor in an insulating layer to protect the inhabitants from cosmic rays, space debris, and other undesirables.

So. Rotation of habitable section. Look at the Ark from Halo for a beautiful example. No, I'm not talking about scale, I'm talking design.

Halo Ark

What you could take from this is that circles are your best bet. So the habitable zone of your ship should be designed around this concept. But it also has to be able to reliably fly through space, so how to do that? Well, look around and you'll find dozens of concepts. Just to offer a few:

Dual ringed

Single ringed

What you want to keep in mind is two things. One, the ability to dock, take off from your 'mother ship'. So you'll need a section that can counter-rotate so it doesn't screw up the artificial gravity for everyone. I'd advise the second design for that purpose, and make sure to use some kind of logarithmic acceleration/deceleration to make the transition as smooth as is humanly possible. Keep in mind that this section has to be large enough to house several smaller ships for manned and unmanned space exploration. You'll be searching for a new home, after all, and you'd want to minimize risks.

Ship hull requirements!

Something to keep in mind, is the current research done to this end. First thing to remember is space debris. There has been research done that highlights these risks and how to best combat them. Make sure there are thin layers of aluminum to slow down the debris and absorb the kinetic force. Keep these layers separated by some kind of shock-absorbent materials -- I believe the latest was a sponge like material, but it all depends on what you can figure out. Check out: this link and this one for Nasa's current thoughts on the matter for Mars missions (not necessarily pertaining to hull design, but both real-world tech, and more than enough extra information that might well help to further your research).

How about propellants?

Well, there has been plenty of research towards this end as well. In Situ being the more popular, but there have been theories about ionized air being used as well. The problem is that this ejects matter that you won't be getting back, so you'll need to be especially careful with this. I believe the two links from the previous point would prove more useful in this (especially the anti-matter engine proposed), but that isn't yet in our reach to do consistently.

Great, but how do we build the thing?!

Well, that's both simple and complicated. Simple, because it obviously needs to be assembled in space. Complicated because thinking inside the box makes this an expensive means.

Or does it?

SpaceX has been doing research into making it cheaper to do just that -- get materials into low earth orbit, for example. They've designed a rocket that can get you up there, and one that can be reused -- which drives down the costs considerably. Now, if you use the In Situ propellant, combined with this rocket? It would drive down your costs considerably.

Now, once you get your things into orbit, you need to assemble the thing. You can do this the old-fashion way, of sending people up there to do just that. But frankly, that is both costly (you have to pay them) and inefficient (training needed, how cumbersome current spacesuits are, etc) so you're better off with some kind of remote controlled robots to do the assembly for you.

First off, it simplifies things (no need to return them to earth every few months, you can have a team of operators controlling them from earth, and they don't ask for hazard pay). As well, if something happens to the robots, you can have other robots collect them and return them to earth with the next shipment to drive costs down even more. Your project won't get the negative publicity for costing human lives, and it means things can be put on a tighter schedule than it otherwise might.

Ship's built, now what?

Well, with the 'hard part' done, you'll want to test the ship for habitability. So in the next shipment, you want plants for aided oxygen scrubbing, and animals to test if everything is safe for human occupation.

I'd advise taking a variety of both (start with potted plants, rabbits, rats, and chickens). Why? Because the more data you get at this point, the better. In addition to them being there, you want sensors that are continuously tracking air composition, air pressure, temperature levels, radiation levels, and all the fun stuff. If something happens at this point, you're still golden, because it would kill animals, not you and your fellow 'escapees'. Let these beings survive for a year in space. Test effects the environment has on them, and be sure to test your ship in a solar storm (kind of important if you want to survive on the ship for many generations).

And last, but certainly not least: financing the whole thing!

So, we know from other answers that cost is a big thing. So how do we work around that? Well: research. You need to approach many governments/space agencies with a proposition of research. Do not tell them you're building the ship for escape, that's just silly. Say you're a group of scientists trying to prove the habitability of space for humans. Your 'project' is meant to stay in earth orbit, or at worst be a cheap means to travel between earth and Mars (whatever sells the idea better).

Do the scientist thing: produce papers for peer-review based on your findings, play the game for your investors (keep them happy and paying). Then, once you and your fellow 'escapees' feel confident the ship meets your standards, announce that a team will be moving onto the ship for human testing over the course of X amount of time. Once everyone that is meant to be on the ship is on the ship, and you have everything you feel you would need:

Set course for the second star on the right, and keep on 'till morning.

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    $\begingroup$ This is by far the best optimistic answer in my opinion :) $\endgroup$ Commented Aug 24, 2016 at 15:11
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    $\begingroup$ "Morning" has an interesting interpretation when traveling through space. $\endgroup$
    – WBT
    Commented Aug 24, 2016 at 16:07
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    $\begingroup$ @WBT It does. That's exactly why I use it here. In this sense, I mean 'until you get to where you are going'. $\endgroup$
    – Fayth85
    Commented Aug 24, 2016 at 16:54
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    $\begingroup$ Question for the optimist: would propellants not be the driving factor in the ship's design? It seems like reaction mass (barring reactionless drives) would quickly become the biggest factor in reaching another star. It leads to some pretty cool designs - hollowed-out asteroids come to mind. Unfortunately it also means the ship must be designed with a specific range in mind (in delta-V, not in light-years), so it sorta requires our characters to pick a destination. Unless they're content floating among the stars, forever... might be kinda nice actually. $\endgroup$ Commented Aug 25, 2016 at 13:18
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    $\begingroup$ @JohnWalthour Yes, and no. Yes, I agree that the ship should be designed around what its limitations (e.g. due to propellant limitations), but it doesn't mean this is the limiting factor for distance to travel. What does that mean? Well, think about it. With current knowhow, we can use the gravitational tug of Jupiter, Saturn, and Uranus to help satellites go faster, simply by timing the launch right. Is it inconceivable that we could therefore use this to aid in stellar escape velocity? And perhaps use carefully timed bursts and perhaps even other starts, to slow us down in time? $\endgroup$
    – Fayth85
    Commented Aug 25, 2016 at 13:30

You are only taking 500 people. That may sound like a lot, but it is not when you are considering breeding populations, genetic diversity, and so on. With only 500 people:

  1. Everyone has to breed to keep the genetic diversity up. No-one get to choose not to have kids. Now you might argue that donated sperm or harvested eggs will do the job, so the folk who are uninterested in kids don't have to raise them. But that means some other people have to do it, and you can bet your bottom dollar they'll be calling you selfish and/or society insists that you do it.
  2. Everyone has to start and stop breeding on demand. There is no room for a population explosion on a starship. Want 3 kids? Tough luck, your allocation is 2. Want a kid now? Tough luck, you'll have to wait until Old Mrs Miggins pops her clogs.
  3. Everyone has to do an approved job. This starship needs to be kept running, generation after generation. You might want to be a ballet dancer or games designer or the pilot, but what the ship really needs right now is 4 sewage workers and 14 child minders.

So if you want to live in a dystopia, go right ahead. I'll stay here with the cat videos! :-)

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    $\begingroup$ I agree with 2, but for 1: A few thousand sperm frozen up will deal with this. Genetic diversity goes down a bit, thaw a couple samples. $\endgroup$
    – Joel
    Commented Aug 24, 2016 at 22:45
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    $\begingroup$ Um, screw natural genetics. If you can afford the ship and all the other technology it requires, you can throw in a few % of a % of that cost for artificial dna synthesis with algorithmically generated genetic diversity. $\endgroup$ Commented Aug 25, 2016 at 3:46
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    $\begingroup$ @DrBob Janet and John should do what they're told or they'll find themselves on the wrong side of an airlock. $\endgroup$
    – darthzejdr
    Commented Aug 25, 2016 at 10:12
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    $\begingroup$ Old Mrs Miggins can be made to pop her clogs: that hydroponic farm's not going to fertilize itself. $\endgroup$
    – yatima2975
    Commented Aug 25, 2016 at 13:01
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    $\begingroup$ @darthzejdr: You're not going to blow valuable resources out the airlock. Janet and John will be "sent to the farm". $\endgroup$
    – TMN
    Commented Aug 25, 2016 at 14:36


I like to examine naval ships for estimates like this. They're the largest mobile structures on Earth, and require people to live together for months at a time. For reference, let's look at an Iowa-class battleship. It has a crew complement of around 2,000. You're very concerned about living space, so we can give everyone 4x the living space the US Navy does it's sailors. This is still going to be pretty cramped, honestly. While it's true you won't need weapons, the space taken up by weapons on the battleship will be taken up by advanced propulsion, life-support, and structural systems. So, to break it down:

  • It takes NASA about \$10,000/pound to put things into space.
  • An Iowa-class battleship weighs about 50,000 tons
  • It would cost NASA $1 trillion to put an Iowa-class battleship into space. Probably more, since it would have to be done in many, many trips, and this doesn't take into account the cost of the spaceship carrying the battleship.
  • For reference, this post estimates people have, in our entire history, sent only 11,575 tons into space.

This doesn't even take into account developing the technology for a spaceship this size, keeping that many people alive, constructing the ship (in space), etc. etc. etc..

Essentially, you're better off buying an atoll, living and preparing on the atoll for a few generations, and every century or so see where humans have gotten technologically, and then re-evaluating.

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    $\begingroup$ Sorry, but this is just fake comparison. You can't compare ships, which utilize the fact how water works, thus weight is not really problem, to spaceships where pulling it into space cost big money, so weight is problem. $\endgroup$
    – Colombo
    Commented Aug 25, 2016 at 0:24
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    $\begingroup$ Given that no one's made a spaceship that size, made to carry that many people that far through space for that long, there's probably four people on the planet who could run some quasi-real numbers. That being said, it's going to have to be about battleship size, and even if you swapped out steel for titanium, we're looking at ~28,000 tons. And you'll make up a fair amount of the cost difference in titanium vs steel prices. And even if you didn't, we're still talking hundreds of billions of dollars. In other words, "Mr. Scott cannot give me exact figures, Admiral, so... I will make a guess." $\endgroup$
    – Azuaron
    Commented Aug 25, 2016 at 1:23
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    $\begingroup$ If you did need to put something that size in orbit, you would be scaling up to the point where you approach a lower multiple of the energy cost (about $2 per pound) rather than the current expensive means. You can't launch people with a rail gun, but you could launch deck plates. $\endgroup$ Commented Aug 26, 2016 at 10:50
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    $\begingroup$ Given that we send non-human cargo to space all the time, all the pieces of the ISS, satellites, etc., if the cost savings were really that extreme we'd be doing it. Anyway, the question is about current tech, and no one's using a mass driver for space launches, so it can't be considered "current". $\endgroup$
    – Azuaron
    Commented Aug 26, 2016 at 11:07
  • $\begingroup$ Lets not forget that the Iowa class battleship is a weapon of war, with thousands of pounds of guns, armor and ammunition that simply won't be required. $\endgroup$ Commented Apr 27, 2017 at 11:53

Short answer: Not currently feasible with our current technology, or any we're likely to get in the next generation or two with the current intensity of research.

Long answer: Probably the biggest challenge (and there are many massive challenges here) is the creation of a working "closed ecological system" or biosphere. We have not successfully managed to create a contained, working multi-year biosphere here on earth, yet, and that should probably be the first step.

Biosphere 2

There have been attempts. Biosphere 2 was one, which highlights many of the challenges that such efforts must face:

Biosphere 2 suffered from CO2 levels that "fluctuated wildly," and most of the vertebrate species and all of the pollinating insects died. Insect pests, like cockroaches, boomed. [...]

clogging filtration systems, unanticipated condensation making the "desert" too wet, population explosions of greenhouse ants and cockroaches, and morning glories overgrowing the "rainforest", blocking out other plants. [...]

The oxygen inside the facility, which began at 20.9%, fell at a steady pace and after 16 months was down to 14.5%. [...]

carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate, thereby sequestering both carbon and oxygen. [...]

a severe dispute within the management team led to the ousting of the on-site management by federal marshals serving a restraining order, leaving management of the mission to the Bannon & Co. team from Beverly Hills, California. At 3 am on April 5, 1994, Abigail Alling and Mark Van Thillo, members of the first crew, allegedly vandalized the project from outside, opening one double-airlock door and three single door emergency exits, leaving them open for approximately fifteen minutes. Five panes of glass were also broken. [...]

Mission 2 was ended prematurely.

Others include MELiSSA and BIOS-1 through BIOS-3, which were more successful due to being on a smaller scale, and less "closed".

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    $\begingroup$ Regarding Biosphere 2: Where were the tv cameras, this sounds like a drama spectacle to exceed most reality tv! (they could have funded a Biosphere 3 & 4 with just the one season!!) $\endgroup$
    – MER
    Commented Aug 25, 2016 at 2:20
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    $\begingroup$ That's no surprise. 14.5% oxygen levels is literally 25% below minimum breathing content, which is around 20% oxygen. To simply stay alive at that point would be exhausting and sleep or unconsciousness would spell slow brain damage. I don't think anyone would volunteer to that kind of job without being lied to, and when the truth came out what do you expect people would do? $\endgroup$ Commented Apr 27, 2017 at 11:50

I won't even bother with a cost estimate because firstly you would need to focus on the how. We are of course talking about something that was never done before and a little beyond the limits of humankind right now. But then so was the first Moon landing.

First off, if you want to have a living space that exists for centuries you'll need a recycling system for every resource necessary for human survival. Think Fallout Vaults in space + storage tanks. Yeah, it's gonna be really, really heavy. For me this is pure science fiction, as humans need the biological fauna in the air to maintain several core functions like digestion, and essentially will lose a small amount of this mass to energy anyway... requiring a massive initial store if they hope to replenish this energy loss for centuries.

This system will take easily 50x the living space of a crew member - per crew member - if it's possible at all. If someone wants to edit this with something I don't know, they are welcome to, but even if we had systems like this that would work on the moon, we don't really have the materials to lift something that heavy into space.

As for the 500 men, I believe the simplest method using current technology would be to send up around 30 cargo launches and drop pieces of the ship into orbit, then stitch the vessel together in high earth orbit. Doing this allows us to avoid the stress a 500 man vessel would put on the ship as it fights gravity on liftoff, but would make it unable to land elsewhere, so you'll need a landing probe. Then you need fuel. Antimatter would be the first call of the science fictionista, but realistically speaking you're mostly gonna be stuck on solar sails and ion drives. There are the new omnidirectional-drives that came out of NASA a few years ago, and a few other things, but nothing concrete.

We could do it, it just would take the entire earth's efforts for several years.


The L5 society was a group like what you describe, and spent a lot of time and resources trying to answer this question (see publication archive here). The path they planned to take through space was similar to Earth's, but sixty degrees behind (or ahead) in the orbit around our Sun (which in turn moves around the galaxy which itself moves through the universe). They've since merged with the National Space Society, with a stated vision of

People living and working in thriving communities beyond the Earth, and the use of the vast resources of space for the dramatic betterment of humanity.

Check out especially their section on Space Settlement and the links in the blue box at the top of the page, particularly Orbital Settlements if you want to keep traveling through space a reasonably constant distance from a significant source of energy.

Also, if you haven't seen it already, watch WALL·E, which is premised on a scenario very similar to the one in this question.


A ship so large would not reach escape velocity with our current technology. You would likely have to assemble the ship in orbit, a bit like how the ISS was constructed.

This would be immensly expensive, considering that the Atlas V costs NASA $20,200 per kg sent into space. Construction of this ship would take several generations even with NASAs funding. After this, you need to transport the people, equipment, plants, food, water, anything else up into space too!

Also consider that travelling at the speed of the Voyager probes (17 km a second relative to the sun), it would take you nearly 10 years just to reach Pluto. The most earth-like planet that has been discovered is 1400 light years away, so it would take nearly 25 million years to travel there at the speed of the voyager probe.

Unless you were in suspended animation (current technology has a 100% death rate) , you would never live to see that planet. In fact, if you sent a newborn child and its parents into space on this ship - travelling at 17km per second - the newborn would have travelled 75 billion kilometers by its 95th birthday. Sounds a lot? That's almost 0.008 lightyears!

So the short answer is yes, it might be possible, but you would not live long enough to see it happen. In fact, if you built a generation ship in the hope your grandchildren's ancestors will make it there, i am willing to bet that new technology on earth would be invented before they reached the planet, and the human race would fly out to overtake the original ship.

  • $\begingroup$ I'm not in rush, I know many generations will reach any planets suitable too live. Plan is to make ship which eventually reach it with living crew. $\endgroup$
    – user902383
    Commented Aug 24, 2016 at 14:23
  • $\begingroup$ in that case, a generation ship is your best bet. $\endgroup$
    – Aric
    Commented Aug 24, 2016 at 14:25

You have already planted the seeds of your failure by including any other person. You are packing along the problems you are trying to escape. Even if these people are like-minded, you cannot guarantee their children will conform to the rules of your new world, or that power structures evolving within your group will corrupt your citizens into kitten-obsessed fools. See: Rama II

Imagine the obsession with Old Earth Kittens when they don't have any cats of their own to play with. Someone is likely to smuggle a favorite pet aboard your vessel, which will then be cloned to meet the demand for adorable pets. When your crew has eventually killed each other off, leaving the kittens to eat the evergreen algae supply and evolve on the self-maintaining ship into intelligent beings, the new Homo Felinus will return to Old Earth, determined to satisfy their own obsession with the pictures of adorable human babies they've found aboard their world. See: Seveneves

Your question isn't "I don't want to live on this planet anymore", it's "I don't want to live with this species anymore". Answer: Sorry, but you're stuck "here" with us, no matter where you are in physical space.


Nobody has mentioned clanking replicators yet?

OP, I have the answer. All you need to do is build a robot that can build a copy of itself from the raw materials available to it in its environment, under its own power. Then you fly this robot out to a rocky moon somewhere, wait a few years as it disassembles half the moon into useful robots, and then wait a little bit longer as you program those robots to build the ship you need. You then tell the bots to fly that ship over to you, you get on, and off you go. Who cares about Earth's GDP when you can logarithmically turn parts of the material universe into production?

Oh, and one little thing - you're probably going to want to make sure the robots never, ever, under any circumstances mutate.

Pro-tip: this won't work. But what's stopping you from trying ;^)

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    $\begingroup$ On the other hand, if the von Neumann probes were dark, it would explain a lot $\endgroup$ Commented Aug 26, 2016 at 10:55

No, it's not feasible at all. There are a million reasons why it wouldn't work, but I'll just touch briefly on the major ones:

  • There is no drive that will take that much mass that far. Even Voyager 1, after 38 years, is only 25 light hours away, and that was a 825 kg probe.
  • There is no energy source that will power the drive and life support. Nuclear is too heavy, solar won't work once you leave solar system. I guess you could try wind...
  • There is no system for maintaining a closed system with such a community, or keeping the ship maintained, that long. You will need inputs, which you can't get in outer space.
  • You will not be able to grow enough nutrients to feed everyone a balanced diet.
  • Space radiation and other hazards would kill everyone.
  • The construction of such a spaceship is very difficult. If every nation of the world made it their #1 goal, just taking 500 people to the moon and back would be very costly and take decades. What you suggest is just inconceivable.
  • 500 people is too few. The children will be inbred and social order will collapse within decades. There won't be enough specialists in medicine, engineering, and other key disciplines to maintain the ship. There's not enough resources to train people in highly specialized professions, so future generations will be even worse.
  • If you somehow obtain the resources and start such a project privately, this will cause global economic and political instability, which will come back and destroy your project.

You don't like cat videos? Go start your own country and make them illegal. Better yet, just run for office in yours, or start an advocacy campaign, or... Well, anything else than building a generation ship.

Incidentally, what will be your ship's policy concerning asking questions on StackExchange?

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    $\begingroup$ I agree on many of your points. But Voyager 1 travelled about 180 AE since launch. 1 AE is approx. 499 light seconds, i.e your mentioned 8.3 light minutes. That makes a travelling distance of approx. 25 light hours which is pretty impressive. I am also unsure if the weight of the object is that important once travelling in space. $\endgroup$ Commented Aug 25, 2016 at 14:31
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    $\begingroup$ I agree. I think the major drawback would be: Cold. Lots and lots of cold. Oh, and darkness. At the currently available speeds, the sheer amount of time away from a Sol disrupts any of our current means of power, food, or heat generation. Perhaps a nuclear fuel plant could provide all that was needed to sustain life, but for safety, you are going to need at least 1 layer of redundancy (for maintenance and repair) more than doubling the expense and time. $\endgroup$
    – Jammin4CO
    Commented Aug 25, 2016 at 18:25
  • $\begingroup$ @Jammin4CO Space is not cold, it's a near vacuum. Heating isn't the challenge, cooling is. $\endgroup$
    – Superbest
    Commented Aug 26, 2016 at 0:36
  • $\begingroup$ @Superbest Vacuum is an excellent insulator. But according to the attached article, when there is no Sol for radiation warmth, it is cold. science.nasa.gov/science-news/science-at-nasa/2001/ast21mar_1 I appreciate the challenge though, you made me think and learn. :-) $\endgroup$
    – Jammin4CO
    Commented Aug 26, 2016 at 16:17

Transform an Asteroid

enter image description here

I would suggest that your 'spaceship' actually be a medium sized asteroid. Build shelters, perhaps underground to help shield from radiation and debris, and attach propulsion systems at various points such that the ship is relatively maneuverable.

Choose an asteroid that has raw materials for use in propulsion, energy generation, repairs and most importantly has water. It would be good to have dirt so that mixed with human, animal and plant waste, would be suitable for farming (in the shelters). An energy source to keep the lights on would help with keeping plants growing and our biological clocks.

It would also have a bit of gravity without having to have tech to keep it spinning.


Getting investment to mine asteroids should be easy since they are so rich in precious metals - just don't let them know your real plan. Everything needed to get the asteroid here and mine it could also be used for getting it somewhere else while living on it. Send robots to 'mine' and test the materials for economic forecasts. Creating living quarters for robot repair crews is reasonable. Everything needed for mining is also reasonable for 'escaping'.

What's missing?

Mining tools for space and propulsion systems for that massive of an object.


10 to 20 years is a solid guess based on speculation and ignorance.


Longevity (will the asteroid run out of materials before your descendants reach their destinations) and general human interactions as others have already noted.

  • $\begingroup$ The longevity issue may be nullified if the OP picks a home in the asteroid belt and extract materials from neighbor bodies, or - if he's feeling particularly daring - Saturn's rings. The gaps at the end should provide a fairly radiation-free environment. $\endgroup$
    – OnoSendai
    Commented Aug 29, 2016 at 18:38
  • $\begingroup$ Yes this is the best answer if you really wanted to do it. Simple and with the least effort. Another way to fund the venture would be those 500 people need to donate their assets and livelihoods to the cause. If they earn $70,000 / year for 20 years they would accumulate $700 million, not including assets they already hold- a long way towards the cause. $\endgroup$
    – flox
    Commented Dec 4, 2018 at 22:31

While theoretically possible, we lack the technology to do it. And the finances you'd need to do this would probably be much higher than what you'd need to fix earth.

You would need to build said spacecraft in space, since launching something that massive is currently impossible. That means probably thousands of return trips between earth and your space-dock(That you would also need to build).

It would probably be cheaper to engineer a virus that would kill most humans on the planet, and then just rebuild earth as you see fit :).

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    $\begingroup$ So you're saying this 1979 film had the answer all along? $\endgroup$
    – da4
    Commented Aug 24, 2016 at 13:52
  • $\begingroup$ I was planning to fund it by using crowd funding platform. I don't think i will get much support by asking people to fund research on deadly virus which kill them all. $\endgroup$
    – user902383
    Commented Aug 24, 2016 at 14:00

Looking at the wiki entry for the ISS, it took the combined efforts of 26 countries, $150bn of finance 18 years to build. At any one time the station can support 6 permanent crewmembers. We support the crew from Earth by sending the ISS supplies. They're not exactly growing food in abundance but they do have some small plants: http://www.nasa.gov/mission_pages/station/research/10-074.html.

Thus food and water would quickly run out without contant supply of resources from Earth.

The station is also not traveling space (it's in orbit so it is moving) so propulsion would be pretty slow (going or stopping), and the zero gravity would wreak havoc on people's health over a long period.

From what I can tell we don't quite have the technology for prolonged space flight, the costs of the project would be staggering (as Nex Terren pointed out), and it would likely take the a significant portion of the lifetime of your 500 people to build.

However, 50years ago the same could've been said for the cost of an international space station. So it's not unlikely that prolonged space travel would be quite feasible in next decade or so.

  • $\begingroup$ Interestingly, one copy of SpaceX Starship has more interior volume than the whole ISS, and will likely cost much less than $10B in development costs before it reaches orbit. The $150B price tag of the ISS really highlights how inefficient NASA is. $\endgroup$
    – user4574
    Commented Sep 14, 2023 at 1:04

The ship itself is barely possible, if very unlikely, with current tech. You would need to be able to reach Mars at a minimum, more likely the asteroid belt. One of the moons of Mars, or a suitable asteroid would become the base of your ship. If enough life sustaining resources cannot be found locally while converting said chunk or rock to a ship, then they would have to be shipped up out of the gravity well. That would take both time, money, and more resources.

If the recent research about electrically generated thrust is in fact accurate and can bee scaled up (yet to be proven) you would then also have the engines necessary for the journey.

Sadly, we lack the knowledge and experience necessary to create sustainable, habitable biomes.

Socially and genetically, we are not in a good position to build a generation ship at this time.

All things taken into consideration, it does not seem currently possible without some sort of a McGuffin (or two) to cover our lacks.


Centuries? With current tech it would take 30,000 years to get a probe to our nearest star, Proxima (as they say in the news today as there's a planet there - lucky!).

However, as Proxima is a small star that spews out so much deadly radiation, you'd have to go to the next nearest, which I think is Tau Ceti, 4 times as far away and possibly still uninhabitable, even if it does turn out to have a planet in the right zone that has the right atmosphere, and no Ceti-dinosaurs (or whatever).

So you're pretty much on to a loser right away, considering all of recorded human history is roughly 6,000 years old and you have to spend 5 times that just to get somewhere bad... you will either have to stay on board forever, or stay nearby in orbit.

So a world-ship that can sustain a population has to have quite an extensive ecosystem (eg Earth itself is one), complete with enough materials to self-sustain for millenia. It doesn't have to be as big as the planet but it will have a maximum sustainable population, but I think you will underestimate how big it still needs to be to house only 500 people. If you have technology then you will also not only need to be able to maintain it, but also have to maintain a society capable of understanding how to maintain it - and note: a priesthood that knows the magic words to turn the big atmosphere machine on and off isn't going to cut it, you'll have to have proper engineering understanding that can also cope with changes in society that will inevitably occur over 5 times the length of human history!

Or you could sit in orbit as a new independent "country" and trade with the planet below for whatever they need. This is far more practical until (or if!) someone develops a FTL drive.

  • $\begingroup$ To clarify for those who don't know FTL stands for Faster than light $\endgroup$
    – Sarfaraaz
    Commented Aug 26, 2016 at 12:13

We do have the ability to construct a massive ship, but we don't have the technology to launch one. Your best bet is to construct the ship in orbit around the moon. That saves you the large amount of fuel you would need to get it off the earth.

The diameter of most payloads on existing rockets is limited to just a few meters. Any ship you could construct in orbit using conventional rockets would have to be made of hundreds of small modules, either put together like a honey comb (which would actually be pretty rugged in case of hull breaches), or a series of segments like the ISS.

Also, if you want everyone to survive the radiation, the hull would need to be metal that is several feet thick. Also having a hull that thick would be necessary to survive thousands of years of colliding with space dust and micro-meteors. That would be way to heavy to launch from the ground.

Secondly shipping raw materials from the earth even to low earth orbit is about $2000 a pound at todays commercial prices. The moon is actually pretty rich in Titanium, which you could use to build the hull. It could be much cheaper to set-up a mining and casting operation on the moon that could fabricate the largest metal pieces of the ships hull.

You could use a space-elevator going from the moon's surface to lunar orbit to get the large metal parts from the surface of the moon into orbit around the moon where you are building the ship. That would be significantly cheaper and easier than rockets. A space elevator from the earth is not possible with todays technology because carbon-nano-tube ropes with sufficient fiber length are not yet mass-producible. But a space elevator from the moon is possible with conventional steel cable due to the lower gravity. Companies like LiftPort (www.LiftPort.com) have already developed every part of the space elevator technology and are only awaiting more money, and a customer.

Your ship will need to be completely self-sufficient once its flying, so you will need machine shops on board that can make or repair every part of the ship, and fabricate every type of micro-chip or circuit card.

As it happens, you can save a lot of money by fabricating the machine shops on the moon as a module, and then using them to initially build the rest of the ship. At some point in the construction, the fabrication facilities are moved from the lunar surface to become part of the ship itself. That means that you get most of the cost of the moon base for free since it was really just part of the ship.

Also, very importantly, by using the ships own machine shops to initially build the ship you prove that you can really repair and replace any part of the ship using the tools and processes available in those machine shops. It eliminates the possibility of forgetting something until after launch.

Over time things on the ship will break. Those machine shop modules will need to make or repair every part of the ship, and fabricate every type of micro-chip or circuit card. Also you should have multiples (at least 3) of every tool or system, so that if one breaks there is a backup. Also, its better if each backup system is not identical so they don't all fail at exactly the same time due to the same disaster.

You will need a nuclear reactor to power the ship. A solar array won't generate much power as you move away from the sun.

The trip time could be just a few years or decades if the planet is in our solar system, or perhaps one of Jupiter's large moons. The trip time will most likely be 1000s of years not 100s if the planet is outside our solar system. The ship design would be vastly different depending on which scenario you choose.

If you just need to travel a few years/decades you could get away with just recycling water and air, with a huge storehouse of dried/canned food. If you have to leave the solar system then you will need to recycle everything.

We do have recycling technology. The toilet on the international space station for example recycles all the urine back into water for the astronauts. But of course plants will do that also if you like.

I already mentioned some price cutting measures, but its worth noting that one can't really estimate the cost of this design by comparing it to historical rocket prices which are based on the way the US government builds things by bidding them out to way over-priced defense contractors. The reason Space-X was founded was because Elon Musk realized that the price that Boeing/Lockheed were charging the U.S. gov for rockets was about 100x the cost of the raw materials.

Secondly, building a much larger ship would probably get a further price break due to economies of scale.

Thirdly, the 500 people who are going on the ship need to know how to build it anyways in case something breaks. So they might as well build it themselves the first time (so you save a lot on labor costs).

A good portion of the people you bring will have to be PHD level scientists and engineers who are capable of doing the ship design. Elon Musk, founder of Space-X wants to make mankind a multi-planet species. So someone like him might be willing to pay for the construction of the moon base, in exchange for your group doing the design and construction work for free and then giving him the rights to sell access to the base, or license the plans to others for profit. It really would be a great deal for him because most of the cost of developing anything is the labor cost to all the scientists and engineers, and techs who build it.

In fact every part of the ship design could be license or sold for profit to help finance further construction. There are plenty of private billionaires and governments who might be interested.

You may be able to lease access to the moon base to venture capitalists interested in mining precious metals from the moon.

Private billionaires are often motivated, adventurous people, and maybe some of them will want to go too. They may see great opportunity in being in on the ground floor of the founding of a new planet. So if you could convince a few dozen of them to go along that could provides some funding too.


Tracy got it mostly right IMHO.

If you need a ship for 500 people, don't build it here and fight gravity to take it out; hollow out an asteroid and move in.

enter image description here

Called Terrarium, this kind of space habitat should be fairly easy to implement: Capture an asteroid, bring it to Earth orbit, then proceed to drill until you reach a safe distance underneath - enough to protect an initial team from radiation.

Instead of building structures on its outer surface, do it on the inside. If you keep the asteroid spinning, centripetal forces will generate something akin to artificial gravity on the outer layer.

enter image description here

You may build external structures with the material taken from the inside:

enter image description here

So your total cost to build a spaceship may be only the sum of transportation for the 500 individuals plus enough equipment (drills, 3D printers, solar panels, etc.) to get Step 1 started.

Media sources: Wanderers, by Erik Wernquist; Spacehabs.com, Bryan Versteeg.

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    $\begingroup$ asteroid will fly apart because it's probably a pile of rocks and dust in most cases.It can be used as source of materials, but not in the way you describe. $\endgroup$
    – MolbOrg
    Commented Aug 28, 2016 at 12:51
  • 1
    $\begingroup$ Nice. I liked the short film too. The cool thing about this approach is that the materials gained from hollowing it out could be sold to cover the costs of construction. To MolbOrg's speculation, "there are other important differences in the internal structure of the asteroids. Most are solid, indicating that they must have been molten at some point in their existence. Others are 'rubble piles'. This means that they are loose collections of 'pieces', held together by the force of their gravity." - esa.int/Our_Activities/Space_Science/… $\endgroup$ Commented Aug 29, 2016 at 18:13
  • $\begingroup$ @TracyCramer Off topic, I know, and I apologize in advance: but as an admirer of Dr. Sagan and his work this short film is one of my favorites. $\endgroup$
    – OnoSendai
    Commented Aug 29, 2016 at 18:34

I don't like the direction where mankind is going. We spend more resources to build tools which allow us to watch cat videos than on curing cancer. One day I decided to say enough, and leave this grim place.

As someone else has already observed, you do not actually want to leave the planet, but rather the human race.

So an easier way out would be to e.g. try and escape underground.

Most technical problems related to living underground are the same as those related to living in a spaceship, except when they're much easier:

  • oxygen can be pumped from outside, either regularly or in case of an emergency.
  • no fuel or propulsion issues.
  • artificial gravity is naturally supplied.
  • no risks of collision.

The problem of making good your escape is the same (but somewhat easier; hiding a space launch is hard. You would need to first build a L5 colony, then move it into a cometary orbit and handwave your economic model possibly as asteroid mining, and finally install more propulsors and leave for good. Yes, that's Star Trek's The Galactic Whirlpool by Gerrold).

Of course there's still the problem of getting underground (technical and economical problem, but not the same scale as a generation ship), of staying hidden underground, and possibly to hide the fact to the people themselves, which requires careful geometry and may need mechanical gravity compensation to make the underworld go round (this is James P. Hogan's Endgame Enigma)

If you play your cards carefully you may engineer a generation-long "space travel" that will end up with the ship "landing" on a depopulated world which could still be colonizable, even if the previous tenants left it a mess: Sol III (you might even engineer the depopulation "accident" yourself to get rid of the lolcats). This is more like Hugh Howey's Silo).


What makes you think that the earth is not travelling in space right now? It just happens that you were born on a pretty big spaceship (earth) with a little over a few billion people on it.

Check how the question come up... Where is it come from? Is it because you are bigger than the earth? Is it because you have access to more planets? How? Who are 'You' - the one who got the question? Keep the question. Don't answer. Seek the source of the question.


I would say step one would be to build an orbital elevator. using fuel to get up and down from orbit would be a huge waste of resources.

next step would be to find how to use hydrogen to power devices and propulsion since Jupiter is way closer than inhabitable star system planets. so harvest hydrogen from Jupiter maybe using a similar system used to build the orbital elevator to build an orbital vacuum pipe because Jupiter's gravity is very strong due to it's massive size.

sustainable life needs such as food and water would be your next step to solve. I think other answers here would be better at answering that problem

Then I would say you'd have the building blocks u need. heck, you could maybe blow Jupiter up to get up to speed but that would require so many calculations to make sure you go in the direction of choice (although the force from speeding up will probably turn everyone into mush)

So to use that method you would need some kind of impact dampening. like a long tube facing away from the explosion that would allow some of the force through and a hydraulic system to control how fast the cockpit/living area would move relative to the outer shell.


Step 0: Fund a space elevator.

Step 1: Build the space elevator.

Step 2: Make money with your space elevator.

Step 3: Build your ship in geostationary orbit using your space elevator.

The biggest cost factor for any space mission is getting it into orbit. And there is just no way around wasting tons and tons of fuel for each ton you deliver to low earth orbit. And that's only for low earth orbit. With a space elevator, you just get so much more efficient.

But it's not just that you get efficient, you'll open a new, very cost efficient route to space. People will love it. And they'll throw their money at you, just to get a glimpse at the earth from geostationary orbit. Or to deliver payloads into other orbits cheaply and safely. Or launch missions to other planets from the far end of your elevator.

With this kind of steady inflow of money, you can start building stuff that makes life in space easier. Start with some serious stations along your elevator, especially a huge one in geostationary orbit. The beauty is, that you can build step by step, with each step slightly enhancing the lifes of your guests, or expanding your resources to host more guests, host them for longer periods, feed them with space grown food, etc.

Only when your ship is ready to leave will the rest of humanity realize that they'll be left behind...


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