Question is ultimately asking why would we do this? A few parameters first...


  • Our current knowledge of physics is correct and there is no such thing as faster than light travel, nor is there any 'wormhole' or other connecting device between the two systems. Communication is no faster than light
  • Human lifespan is ~100 years on average by this time, immortality is not obtainable
  • We are capable of travelling around 5% the speed of light for this journey (or 1 light year every 20 years of travel)
  • 14-15 light year journey, or slightly under 300 year journey (time dilation ignored at this point), meaning 4 generations of humans will live before arriving.

This puts several limitations on this new colony. They are fully isolated from Earth as communication is at least 15 years in transit, and is at most capable of sending new technological ideas/inventions as blueprints with a 15 year lag time (in this story line, quantum entanglement eventually comes along as a method of faster than light communication, but when the ship leaves this idea is nothing but theory). Trade between the colonies is impossible due to the 300 year in-transit delay. There is really little gain for Earth, other than knowing humans now exist outside of the solar system.


It's the 22nd century and humanity is more and more reaching into the stars, but is completely unable to resolve the issue of interstellar distance. On Earth, mobility of populations has greatly increased and the world is far more homogeneous in general. A global government has formed with countries still existing, but more as states of this global whole. People of all races and from any nation (with a couple exceptions) are now relatively free to travel and settle where ever they would like. Freedom and individuality is still a core belief, and though the pro-humanity concept is there, most people do whats right for them before 'the interests of humanity'.

This move isn't the most popular and is dubbed 'viral colonization tactics' by those voices disagreeing with the move to send humans like this. It gets referred to as sending our spores to infect the rest of the galaxy. Assume support is around 50/50, such that delays, risks, and other factors may mean a politician is risking their career by doing this, however there is enough support to get the idea off the ground.

We have had contact with another alien race and it's generally understood that we are not alone. However the contact has been very minimal and we understand little of 'galactic politics' or the species involved in it


Signs of an alien race were found spotted throughout the system as technological artifacts the we recovered and studied. Most of the artifacts were discovered in orbit of Jupiter as a crashed ship, however other jettisoned parts were discovered around in orbit of Neptune. Actual contact with a single alien representative was made after an explorer from that species came into contact with human explorers looking for more artifacts. Contact was brief, however entirely recorded. Alien was hesitant as he could not speak for his race as he was 'just an explorer'. There is mention of a second alien race as well, though not described. Alien insisted repeatedly that they are peaceful and intend no harm.

The Moon has been partially colonized and holds the space dock in which the ship could be created.

The question:

What motivations would a worldwide government have to put together this mission? Is the knowledge that humanity now exists elsewhere in the universe and some distant time where alternate forms of interstellar travel exists that may allow us contact with them enough to make this investment worth while? On a government scale:

  • Money and time invested by Earth to make the space craft need to be justified

  • Staking political careers on the idea that this is worth it

And the question #2

  • What would motivate an individual to sign up for this mission, well knowing that they will never see the new world they are to colonize and are forcing their children, grandchildren, and great-grandchildren to the same wordless fate so their great-great-grandchildren have the possibility of colonizing a new planet isolated on their own?

Side note - this is integral to the story line as a future holds these colonies linking up under new technologies. But is the idea that we might one day be able to enough to start it now?

Addendum 3:
More than one colony ship will make the journey, all to separate stars...hence the 'viral tactics' reference where we blindly spore and hop to 'infect' as many planets as possible. The more reasons the better.

  • 1
    $\begingroup$ Regarding communication, by stating "15 years in transit" you mean from the final destination/the colony to earth and not during travel, right? Also, could you specify the "contact to aliens" part? Because if they are just sending out signals, like we do on earth and we happen to intercept them, then they might not even know of us but just make the same mistake of randomly letting us know of their existence. $\endgroup$
    – kaiser
    Commented Nov 29, 2014 at 0:49
  • 1
    $\begingroup$ Btw, for some good ideas I recommend watching this overdramatic documentary that has some interesting points on multi generation space travel to colonize different worlds. Don't take it too serious, but it's ok for scavenging ideas and to look at topics you might have missed (like religion, time spans to launch rockets for parts, etc). $\endgroup$
    – kaiser
    Commented Nov 29, 2014 at 1:21
  • $\begingroup$ @kaiser - updated the alien contact section. It's minor contact with an explorer and not much else. Explorer is actually trying to discover why his colleague crashed and makes contact with us while human explorers are trying to find the rest of the crash site artifacts. 15 years in transit is just a reference to our communication can't exceed the speed of light, so a message sent from the colony would arrive at earth in 15 years at best (probably longer) and vice versa, earth could send new blueprints and documents that would take 15 years for the communication signal to arrive. $\endgroup$
    – Twelfth
    Commented Nov 29, 2014 at 1:26
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    $\begingroup$ " There is really little gain for Earth, other than knowing humans now exist outside of the solar system" - according to Elon Musk's VERY persuasive argument, that's an enormous, worth-anything, gain. You have just significantly hedged your extinction risk as a species/civilization. $\endgroup$
    – user4239
    Commented Nov 29, 2014 at 16:17
  • 2
    $\begingroup$ Does your technology include cryogenic freezing? This would help you get over some of the time delay for a large percentage of the colonists. Something along the lines of 2001 A Space Odyssey (without the computer killing all the passengers...). $\endgroup$ Commented Nov 29, 2014 at 16:27

10 Answers 10


Let's listen to the head of the colonization movement, who happens to give a speech about this topic right now:

Ladies and Gentlemen, thank you for giving me the opportunity to tell you about the importance of colonization.

As you all know, there was short contact to an alien species, but we know next to nothing about those aliens. So who tells us that the aliens will not destroy humanity on earth, for whatever reason unknown to us? After all, we have no idea of how those aliens think. All we know is they are there (because we have had contact shortly), and we know they know we are there. We don't know if they are hostile. We don't know if they think we are hostile. And we don't know what sort of technology they have. Maybe there's an absolutely devastating weapon already on the way to earth, and there's nothing we can do about it. There's no way for us to tell whether that is the case.

So what can we do? Well, our only way to make reasonably sure that we survive is to spread. We have to create colonies. Colonies the aliens don't know about. Colonies which survive even if earth doesn't. In addition, if an attack is approaching from the direction where one of those colonies is, the colonists can warn us, so we can at least have some time of preparation. After all, information can travel with the speed of light, while weapons are necessarily slower. So they will be able to tell us in advance about weapons that approach us, and how we might prepare for such weapons.

So you see, it is absolutely mandatory to have colonies, for the protection of mankind. Either to early warn earth about an attack, or for survival in case earth doesn't survive an attack. And since it is known that there are aliens, and it is not known that those aliens are peaceful, we have to assume that they may try to attack and to destroy us at any time, so we have to be prepared. And to be prepared means to have colonies.

If you are interested in being a colonist and saving mankind, please put your name into the list you'll find to the left of the exit. Thank you very much.

  • 1
    $\begingroup$ +1, but why "Left of the exit"? Are people herded into places all over the world just to listen to that speech? Is TV still not invented? ;) $\endgroup$
    – kaiser
    Commented Nov 29, 2014 at 0:54
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    $\begingroup$ @kaiser: Of course they have interactive TV. And the "exit" button (to return to the program table; commonly just called "the exit") is always on the lower right corner. Left to that, broadcasters can place interactive items, like for example a list where you can add yourself. You see, that sentence does in no way imply people gathering locally. ;-) $\endgroup$
    – celtschk
    Commented Nov 29, 2014 at 8:18
  • $\begingroup$ Oh my, what a slick guy are you? A lawyer, I guess... ;) $\endgroup$
    – kaiser
    Commented Nov 29, 2014 at 12:56
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    $\begingroup$ "Would like like to know more?" $\endgroup$ Commented Feb 1, 2015 at 15:56

Some other reasons:

  • Wealthy families (or tribes or religious sects) seek to establish places where they can be "free" of Earth's world government. (a la New England, Maryland, and Pennsylvania.)
  • Earth's world government seeks to permanently exile particularly rich or admired people, without seeming to kill or imprison them. (a la "Australia".) If space travel is very cheap, it can even be used for ordinary criminals or political undesirables.
  • It is a retirement plan for world leaders. Politicians can hand over power, and join a colonization mission, safe in the knowledge that nobody can haul them back to answer for their crimes (real or alleged). Plus, they can choose whom they will travel with.
  • It is a matter of prestige for wealthy families (or tribes) to have a colony. (a la Maine.)
  • A religious sect concludes that they can found a colony on their "heavenly" planet.
  • A spectacularly valuable natural resource can be found in a colony system. Perhaps magnetic monopoles? Perhaps anti-matter?
  • Spectacularly dangerous experiments can be done in such a colony, with little risk to Earth. For example, radical genetic engineering, anti-matter manufacture, or contacting the aliens.
  • Some people are just impatient to "get started".
  • It's a lottery. Enough people want to do it, and are willing to pay for a 1 in a million chance, to be able to pay for it. And the government is desperate for lottery profits.
  • Pork barrel. All of the money spent (for space travel) is actually spent on Earth. Suppose some politically influential areas are dependent on xenon distillation, or huge ion thruster manufacturing, or expensive-but-light-weight reactor designs, or deuterium refining, or orbital launch systems, or waste-to-food-and-air converters. Suppose there is only a limited market for these products in the solar system. Suppose the only alternative to purchasing these products from these areas is to pay welfare to these areas. The colonization plan might be a politically viable way to shuffle money to these areas.

If economics are the only factor, it makes more sense to continue researching propulsion technologies, and building up Earth's industrial base. If the speed can be doubled in 25 years, that saves 150 years of travel time. Quadrupling speed in 50 years saves 225 years of travel time.

  • $\begingroup$ My issue with the maine/new england/pennsylvania solutions is the initial colonists would never survive...trip to new england is long, but the life was for themselves not some future generation. Dangerous experiemtns, lottery, religion all work +1. I don't get how pork barrel applies here, mind expanding? $\endgroup$
    – Twelfth
    Commented Nov 29, 2014 at 3:57
  • $\begingroup$ "If space travel is very cheap, it can even be used for ordinary criminals or political undesirables." In that case, you also have to consider keeping a psychopath with a spaceship from wreaking severe havoc in a suicide crash. $\endgroup$
    – user
    Commented Nov 29, 2014 at 23:52
  • $\begingroup$ Don't tell me humanity wants to spread their spores throughout the vastness of the universe just to make another Pennsylvania! $\endgroup$
    – DA.
    Commented Dec 2, 2014 at 7:47

To add to Jasper's excellent answer:

  1. Main reason: You're hedging against ELE (Extinction Level Event)

    Another answer mentioned alien threat, but ELE's can happen for other reasons as well - meteorite, supervolcano (Toba nearly led to humans becoming extinct in the past; and we are right up against Yellowstone deadline), super-plague, nano-gray-goo, Large Hadron Collider Creating Black Hole, Chthulu wakes up, Singularity, Judgement Day (of Terminator type, not religious type).

    Elon Musk spoke on this extensively when discussing his vision of Mars colony in real life.

  2. Early investment.

    Yes, the colonies aren't expected to produce much benefit now. But if technology/surcumstances/etc.. change in the future such that they can - they will have already been there, ready to benefit.

    High-risk investors would be all over that like Lehman on subprime mortgages.

  3. Political freedom

    Plenty of people chafe under the less-free society that invariably gets imposed on everyone due to population density.

    Various libertarian minded (or anarchist etc...) people would be VERY interested in a new frontier, where you don't have to worry about intrusive laws, regulations, coddling the weak, etc...

    In the past, they moved to real frontiers. Wild West in America. These days they dream of seasteading or moving to Vermont. Give them whole worlds to be free in and you have plenty of interested individuals.

    This has the dual benefit: Earth gets rid of "live free or die" people who chafe under "world Government", "daddy government", "big government", and the like - WITHOUT violating their freedom. They go on their own volition, attracted by the frontier. Secondly, collecting such people helps you succeed better in colonization - those ARE the kinds of people who have the psychological drive to succeed as a colonist.


I am going to throw in my ideas formed around the question, which I also understand like this:

  1. What makes you to go far away to never return back?
  2. What would make your children to still want to go there?
  3. What would make your grandchildren to still want to go there?
  4. What would make your grandchildren to build there colony (once there)?
  5. What is there in it for Earth?

Here are several ideas I did have to answer it:

Spacecraft is better place - a.k.a The poor man decision: You are starving, living terrible life in forgotten place with no possibility to change it. Going to spaceship, where all your needs are taken care of, where you have room and everything to raise your kids sounds like great idea. Also it would make you want to send something back, even if the transfer of goods takes awfully long

You had no choice - a.k.a. The final solution for the unwanted. Real example here is North Korea. It is believed that if someone makes move against the regime, the regime is going to punish them, and the whole family tree.

So, here, you are unwanted, and no one really cares what happens to you, or your children. It assumes that interstellar travel is relatively cheap and can be fully automated (so you have no option of changing the course of travel). While humanity survives as whole, no one actually cares if you did.

You deeply believe in your final destination - a.k.a The Heavenly Kingdom: The spacecraft will be populated with group of deeply believing people who will be convinced, that their final destination is the new Mecca of their religion.

It is simply your mindset - a.k.a The Asian solution: Lets stay in Asia for a while. Family is still great deal nowadays and father of the family is still really important. Arranged weddings are still practiced in India (and hell yeah, you are going to need them in such long travel) and the mindset around "create better world for our children ... by creating better children" is still quite huge. People of such mindset could reach the star by waving hand

BTW, one idea to the space travel: One way or another, if you make your interstellar ship to be fully automated and unable to change its direction, you increase your chances that the people on the ship will actually reach their final destination.

  • $\begingroup$ "ship [...] unable to change its direction" I think that's highly unlikely. Given the amount of time the people aboard have to spare they will manage to control that ship if they really intend to (even if that means ripping all the chips out of that HAL 9000). $\endgroup$
    – Ghanima
    Commented Dec 3, 2014 at 9:51
  • $\begingroup$ I am fully aware of that. But still I think that giving the wheel directly to generation 1 is bad idea. What if generation 3 (still on travel) decides they want to go back, because they do not agree with what their grandfathers did? $\endgroup$ Commented Dec 3, 2014 at 10:13
  • $\begingroup$ @Ghanima all you need to do is only give them the delta-V to slow down. $\endgroup$ Commented Aug 16, 2017 at 5:34

I would consider fear of extinction to be the most compelling reason why we humans would actually want to travel such long distances to colonize planets.

To simplify this concept, let me give you a quick example of what I mean.

Imaging that in the near future, astronomers looking up in the sky find a huge celestial object (like a large comet, or a stray planet, or even a black hole!) heading straight for Earth! Depending on how large it is (like a star or black hole) nothing we can do; like shoot nukes at it, will stop this object from a direct collision course from Earth. Some people want to build huge bombs and missiles to blow this object out of the sky, some people want to build huge boosters on the one side of the planet to push Earth out of orbit enough to avoid the collision. The final group realizes that maybe the best course of action would be to abandon Earth altogether and, although Earth will be annihilated, the human species could still survive. They find a habitable planet merely 15 light years away.

Now it doesn't necessarily have to be some celestial object colliding with Earth to cause such a migration. Other reasons could be:

Our sun will eventually explode (billions of years in the future), we should probably leave Earth before that happens.

Global Warming has gone out of control and in a few more years, our atmosphere will become intolerable, a few old-timers remember what it was like to be able to breathe outside without artificial respirators; they hatch a plan to colonize a distant planet that scans have revealed to contain an atmosphere just like the Earth of the "old days".

A second cold war occurs. Fear of nuclear mass annihilation becomes a common threat to everyone. Some people realize that if the "nukes" get launched, then the human race would become extinct. Unless we find a way to colonize other planets first.


I can think of four general Reasons:

  1. Altruism
  2. Escape
  3. Exploration/adventure
  4. Deportation


Some will want to contribute to the expansion and potential survival of the race.


Life isn't good for everyone. Some will take a chance to live under different circumstances even if difficult and uncertain. A life on a ship can be preferable to one in a rat-infested, crime-ridden slum. If children are possible, it might help the lives of offspring.


Excitement. Something new, different. Unknown. Why climb the mountain? Because it's there.


Life experience isn't always from willingness. Society chooses for us sometimes.


Convict colony: Get rid of undesireables, but without having to soil your hands by murdering them.


this sounds similar to "Mayflies" by Kevin O'Donnell. Generational ship. Time delay with communications and advancements in science.

The problem they had was that, while the first generation was all gung-ho. The succeeding generations lost that drive and lost their scientific knowledge.

I'm assuming that your "social engineers" can ensure that all the succeeding generations will retain the same gung-ho attitude of the original crew. Remember parents have no control over what their children want to become or what to study or whether their children want to study at all. Better plan for some redundancy for the people necessary for ship operations.

Motivation for people:

For the adventurers, thrill-seekers, easy sell. From your description it already sounds that earth has "little new frontiers" for these kind of people.

Young military families also.

Some companies might agree to send some of their researchers - drug companies to reasearch dna of plants on other planets. Or if they cant send people - then these companies might want to help with funding for exclusive rights to new discoveries on other planets. It will be a long term investment for them but it will be worth it. Mineral rights alone could be a fortune.

Those same companies might even help with faster-than-light research since it will guarantee quicker returns on their long term investment.


Not the benefit to Earth

The main direct benefit IMHO is not to "Earth as a concept" or a global government or the people back home.

In a realistic scenario, apart of warm fuzzies of exploration, the only positive benefits occur to the actual colonies and to 'humanity' as a whole that includes both Earth and colonies.

Colonists gain opportunities that would be impossible for them on Earth (and would self-select from the subpopulation that desires this tiny set of opportunities specific to space travel). Humanity becomes more resilient, especially to existential threats.

But "government of Earth" ? It would gain some benefits in R&D testing and exploration, absolutely zero benefits in resources obtained, a PR effect that might be positive or negative depending on various random details, a significant cost, and some future political threats, as there are no reasonable ways to control the colonies in the future - it's essentially creating a new civilization that might become cooperative or competitive over time.

There is no direct benefit to anyone staying back home - the invested resources really won't bring any returns back to Earth over their lifetimes, the expansion of the humanity won't give them more space (apart from the minor effect of the people leaving - which could be achieved much simpler by killing them), and the safety of humanity won't prevent their existential threats, rather vice versa - it would make it slightly more likely that Earth gets destroyed, and knowing that humanity lives on elsewhere probably won't make it easier for them when they go down with their planet.

For mankind

The reasons to actually do so are simple - idealistic reasons "this should be done" for the politicians and funders, and personal reasons/ambitions that cause people to do reckless things for glory. History has shown that there always is a significantly large minority of people that find those reasons suitable enough, mostly young males with no commitments (or unwanted commitments), nothing to lose and everything to gain.

Going on an interstellar colonization is practically a far better prospect than volounteering and going off to a far away land to die in someone else's war, and reality shows that there are quite enough people willing to do that.


Others have given the best answers to why any humans would pay for or go on this mission, but an important consideration is whether it even succeeds. After all, your world may have the technology to spot potential farway homes, but that is not the same as colonizing them. Some worlds may be duds. Some colony ships may like space so much, the idea of landing is actually unappealing. Some might decide to camp out in the middle of nowhere, setting up a rest stop on the interstellar highway in anticipation of all the future traffic.

After all, if you have a ship big enough to sustain generations of humans, you have a complete moving world all by itself. The first generation will grow weary of the confinement, but the second generation will never know the freedom of a full planet. By the third or fourth generation, the idea of living on planets may become a full-on heresy, on all the colony ships. This idea was lightly explored in Larry Niven's Footfall.


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