Monday, February 9, 2015

Generation Ships - Travelling Islands in Space

After the rather ironic theme of hibernation and a subsequent 3 year absence, I thought I'd come back with the old SF staple, the generation ship.

I'm not sure where the generation ship idea first came up but I do remember reading a novella by Robert Heinlein - Orphans of the Sky. The generation ship solves the problem of long travel time by basically dooming the crew to die on the ship and their eventual descendants to be the one that reaches the distant star.

The most obvious problem (beside the ethical hurdle of generations doomed to die between the stars) is you need a biiiiiiiiiiiiiiiig damn ship. At least, if you're a still reasonably human civilisation that cares about having a large enough community and so on. It's inevitable that the inhabitants of this ship are going to be as different from us we are from as the colonists on the Mayflower, coming from a civilization that regards a voyage to Mars as something like a transatlantic flight and the outer planets a place to go for cheap hostels and scuba diving in the liquid interiors of Europa and Enceladus.

So, estimates for a ship size range from a tiny vessel with one (female) crewmember impregnating herself to a vast city-ship carved out of an asteroid. On board, there is enough technical know-how, equipment and machinery to last for a flight time of hundreds, a thousand years even - plus all the creature comforts such as parks and soda fountains and a micro-Facebook. Or even a Fakebook with millions of simulated users posting photos of beer coming out of their noses. 

Desperate Housewives! In spaaaaaace!!!

The way the 21st century is panning out, living in space looks it will be significantly easier once you're up there. Technologies like 3D printing and genetic engineering would make it much easier to survive away from Earth once you have access to water, nitrogen and carbon plus metals. Smart materials and true nanotechnology could produce a ship that was literally a living creature, albeit one composed of alloys and exotic composites. VR technologies like the Occulus Rift, once refined, would take away a lot of the cabin fever. Primitive holodecks could even be constructed - certainly the demand for greater immersion in gaming is heading that way. 

Future spacecraft will probably resemble Farscape's Moya more than they do the USS Enterprise...

Herein lies the problem - if we can survive in space, the harshest of environments, why waste all that time and energy bumbling off to other star systems? The answer to that is somewhat paradoxical - if we can survive in space, we can choose pretty much any star system we choose - including close ones that have no habitable worlds. A mixture of asteroids and dwarf planets would be all a spacefaring civilisation needs to flourish. Being able to live with whatever the closest star systems throw at us is going to throw decades or centuries of travel time out of the equation.

Home sweet home for a shipload of travel-weary asteroid miners.

As with any space mission, mass constraints are always crucial. 3D printers, even in the future, may not make the highest precision or most durable replacement parts. The printers themselves may break down, software become corrupted and so on. Laptops sent to the ISS are basically unusable after 6 months in the comparatively benign radiation environment of low earth orbit. And keeping software code stable for hundreds of years will be a challenge - it is possible that hidden in transmissions sent from earth could be viruses tailored to attack the ships' networks. So, you will almost always have a finite stock of basic materials and parts.

This needs to be balanced against simply loading more fuel, thickening the debris shield and flying the mission faster. The problem with advanced technology is that it's harder to make it as robust as lower tech solutions.

Something is needed that can make a reliable replacement or jury-rigged part if the 3D printers go offline for some reason. Thus, 20th century machine shop technology will likely be used and practiced alongside cutting-edge printing technology.

All of this we will learn from building and operating space habitats. The most likely candidates for a generation ship would probably be a space habitat that got gatvol (Afrikaans for ass full) of the solar system and decided to make a star trek (another Afrikaans word) to where it's less crowded. They already know how to live in space, they all know each other and, if they lived in the asteroid belt or orbiting one of the gas giants, they wouldn't be bothered by slow internet surfing caused by the pesky lightspeed limit.

All they'd really need was to strip out all the heavy stuff from their habitat, gather enough He-3 and De, build a big fusion engine and light it. Although most popular SF depicts a single ship alone in the night, it's more likely that the generation ship will be one of many ships, some of them unmanned freighters launched years before with less velocity, all moving and sharing information. It would be a lot easier to talk with another generation ship only 1 light year away than with Earth, 10 light years away, even if you were heading to two different star systems. Once you start slowing down, you could match velocities with the slower freighters, loading fuel and resources. Maybe even using them as lifeboats if things have really gone bad, or crews doubling up on a ship when they only have a few years left to go. On arrival, there should be more than enough asteroids to supply the hungry factories, ready to build roomy space habitats after the generations of travel. Or maybe it's just an asteroid cottage for one veeeerry crazy cat lady.

Up next: artificial gravity.


  1. I don't think we have a strong incentive to open a new frontier until the current <a href="'>logistic growth ceiling</a> becomes constraining and uncomfortable.

    If we break free of Cradle Earth, the Main Belt has an enormous amount of surface area. Further, the entire <i>volume</i> of most of these bodies are accessible. I suspect the Main Belt could support a population of trillions. Opening this frontier would postpone bumping into the logistic ceiling for millennia.

    If we manage to achieve fusion power (other than the sun and stars), the Kuiper Belt and Oort would be the next frontier. And I suspect these populations are thousands of times greater than the Main Belt.

    Unlike the Main Belt, the Oort city states will be separated from their nearest neighbors by vast distances, on the order tens or hundreds of astronomical units. Trade will be more difficult. So there is more incentive to establish self supporting biomes. Biomes enduring for many generations will happen as a matter of course.

    By the time the outer Oort is settled, it would be easy to nudge an Oort city state loosely bound to our sun and depart for interstellar space.

    However reaching other star systems would still be a problem since our neighboring stars are moving tens or even hundreds of kilometers per second with regard to our solar system. If they have their own fusion power, I suspect these expat city states would be content to dwell in the spaces between the stars.

  2. True; but I suspect the pressure to go will be ideological more than economic. If we become a totally uploaded civilisation living in a quantum computing core there's no real incentive to ever leave. But, humans being stubborn and different, will probably send some curious meatsacks out to the stars when and if they develop the technology and acquire the resources.