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‘Generation Ship’

April 21, 2011

For all we smashed the atom, tamed the proton,
There still remained some lines we couldn’t cross:
The onward march of days that Shakespeare wrote on
Remains as steady as it ever was;
Love outruns time – but light is not so spry;
While dreams of flying set our brains aglow
Across the endless wastes of empty sky
Our ships, though quick as light, are far too slow.

A simple journey – routes they’ve done before –
Takes twenty years. We’re going somewhere new.
Could take a lifetime, two, three, dozens, more;
You join, your children join, and theirs do, too.

Still want to join us? Sure? Well, go and pack.
Take all you need. You won’t be coming back.


This poem picks up on the tangent I went off on in the footnote to “Sky-Fever”, about the bleak worldview that you tend to get in sci-fi universes without faster-than-light travel. A mythos like Star Wars very much has its roots in the medieval romances and fairytales which wander across half of Europe – half the fun is the constant swirl of exotic places the protagonists fetch up in. The frisson of excitement conjured by Arthurian placenames like Corbenic, Astolat, Synadowne and Lonazep is pretty much identical, five hundred years down the line, to the one inspired by Alderaan, Tatooine, Yavin and Dagobah.

In universes without FTL travel that kind of exotic whirl is impossible. Unless the protagonists also live sufficiently long that forty or eighty years between destinations is negligible – and my money is on us getting interstellar travel some time before that degree of longevity; we’re currently a lot further on with rocketry than we are bioengineering – space travel becomes a thing of horror rather than a means to adventure. Twenty years or more of travel, most of it unreachably far from human contact, is a lot of time for things to go wrong in.

Really long distances will only be achievable, before super-longevity, by generation ship – the crew reproduce, raise their offspring who become the new crew, and so on. We’ve debated the ethics of this at the dinner table: agreeing to go on a space voyage on which you will die, leaving behind most if not all of your family and culture, is a huge undertaking and one that would be clearly hugely immoral to impose on someone without their consent. But isn’t that what the first generation of a generation-ship crew are effectively doing to their someday children, given that you can’t get off till the end of the ride?

5 Comments leave one →
  1. April 22, 2011 5:07 am

    Similar to the issue raised in Red Mars – The first hundred colonists were screened for physical and mental health, and one of them points out that they basically had to lie;

    (Paraphrasing)”To be the sort of people who are both stable enough to run a mission, but unstable enough to want to give up their whole lives on Earth, that they could probably never return to. They aren’t two traits that often happen together”.

    Basically, the ship they’d built to get to Mars was going to disassemble at the other end, so anyone who went over there was stuck, within radio range of home but unable to go back.

  2. April 22, 2011 8:43 am

    Surely in terms of morality, bringing children up on a generation ship is no more immoral than bringing them up, say, at Plymouth colony just after the landing of the Mayflower?

    Anyway, there is one trick that you can use to travel interstellar distances in a reasonable length of time: time dilation. If you want your spaceship to have artificial gravity, then barring any technobabble “gravity generators”, the only way to do it is to have your spaceship always be accelerating (or decelerating) at 9.81 metres per second per second. At this rate, the spaceship will constantly be pressing against the feet of your astronauts in a way that is indistinguishable from gravity on earth.

    This also has the side of making your ship go very fast very quickly, so that within a year or two you’re pushing against the speed of light. At this speed, time on the spaceship slows down massively compared to time outside.

    With this, a 100 light year journey seems to take just 9 years, a 1000 light year journey just 13, and even a trip to the Andromeda Galaxy, 2.5 million light years away, only seems to take 33 years (if you’re willing to live under 2G gravity, this is reduced to just 17). Space Math has a handy calculator. Of course, Earth time is still ticking away, so that 60-year round trip to Andromeda means you end up back on Earth 5 million years in the future, which would be pretty horrific from an evolution perspective if nothing else – humans would almost certainly have long evolved into other things (5 million years ago, humans and chimpanzees had only just begun to split into different lines).

  3. April 22, 2011 12:58 pm

    Perspicacity: I have been meaning to read the Colours of Mars trilogy for ages. I should probably do something about that. Anyway, yes, that is exactly the sort of problem involved.

    atomicspin: I think the key difference with the Mayflower example – and indeed other Earth-based comparisons – is the impossibility of leaving an interstellar craft mid-journey. A second-generation Pilgrim who wanted to return to Europe, could; a second-generation generation-shipper who wanted to go back to Earth quite possibly couldn’t (depending on the length of the trip and what they found at the other end). If the ship is nudging the speed of light close enough that they’d live to see out a return journey, this (as you say) raises the problem of what they’d find when they got back.

    The aim of conducting a pioneering interstellar journey in an ethical manner raises other questions. How do you manage the gene pool to get healthy new generations of the right size without curtailing your crew’s reproductive rights? (Which, again, the second gen and onwards have not signed up to?) What do you do with recidivists? Imprisonment uses up resources while costing you a worker, but chucking them out an airlock seems like a step too far …

    (Jay and I have been kicking around ideas for some sort of Civ-style strategy/management game where the protagonist is the All-Seeing Computer of a generation ship. It’d be awesome if we could only get it off the ground. Pun not intended.)

    Pushing Ice by Alastair Reynolds has some excellent examples of how brain-breaking time dilation gets at very high speeds. ROT13’d for spoilers: Gur cebgntbavfgf, juvfxrq njnl ol na nyvra fcnprpensg ng gur fgneg bs gur obbx, qvfpbire gbjneqf gur raq gung ragver tnynkl-fcnaavat cbfguhzna pvivyvfngvbaf unir evfra naq snyyra va jung gurl rkcrevraprq nf n fvatyr trarengvba, naq gung gurve bevtvany pncgnva unf orra erirerq nf n arne-qrvsvp svther ol frireny bs gubfr rzcverf.

    Also: Space Math is amazing. Bookmarking, right now.

  4. April 22, 2011 1:53 pm

    Ooh, Pushing Ice sounds interesting. Tau Zero by Poul Anderson is worth a read too. It’s basically about the crew of a spaceship which travels at constant acceleration, but which suffers and accident that destroys its braking systems. The spaceship is forced to keep going faster and faster and time around it gets ever more dilated.

    On generation ships, I almost kind of want to recommend the film “Space Mutiny”. It’s absolutely completely terrible, but in a very watchable way, and it’s about a generation ship that’s been overtaken by later FTL-ish ships, and the mutiny is between the heroes, who want to keep going to their destination even if they’ll never see it in their lifetimes, and the villains, who want to land on the nearest settled world, even if it is a pirate colony. It’s just a shame they ruined that great plot idea on this.

    I suppose one possibility with regards to the human rights problems could be to divide your ship into countries, each with its own democracy, and access to a fixed proportion of the resources. People can move between countries more-or-less freely (much like EU borders). I assume countries would develop different rules, with a spectrum of – for example – reproductive rights, from artificial children only, through strict one-child states, to liberal nations or even large-family theocracies. Of course, the limited resources would nudge things towards small families, but at least this way there’d be a variety of ways to do it, and there’d be at least some choice for those on board (in the same vein to how choice works on Earth).


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