Assuming we are talking about an era when Sol has a thriving space industry and the Solar system is broadly colonized. Current materials science supports structures up to 8 kilometers in diameter, and if large scale graphene production is possible, up to 100km in diameter, at least according to Isaac Arthor.
I am wondering what resources would be difficult for a colony ship to reproduce in-situ on an one way trip to the first interstellar expansions of humanity. I picture a true generation ship might be primarily designed around the transport of some of the largest prefabricated sections of a future centrifugal spin gravity habitat.
- Using hard science to speculate, what types of materials and components would only be available with the massive industry present in humanity’s original home?
I picture the main outer ring frame structure of an O’Neil cylinder, like some kind of curved beam, would be prefabricated and sent in a few pieces for later assembly. If the O’Neil cylinder was to be 8km in diameter, 3 pieces would make the generation ship at least 5.7km long.
-
What is practical to transport assuming fusion is in the cards, as are self replicating drones for resource extraction in a region like the astroid belt, and assuming planets are resource poor gravity prisons we avoid in favor of mobility?
-
How might carbon get utilized for large structure fabrication in space as far as processes?
-
What about metals and space based fabrication. How can you picture the production happening in ways that would only be possible in a highly advanced space based economy?
I know this is highly speculative and I hope the mods will let it fly to ask this. I know most nerds are curious about this kind of thing. I’m only interested in the most conservatively realistic of hard science fiction/futurism.
There’s no reason that we would expand out at the speed of light in one direction. It’s well within the realm of possibility that we can intercept rogue planets or large asteroids to use as long time habitats. Also we can expand in millions of directions at once at sub-light speed. The journey make take a million years, but we’ll reach a million places at once.
I didn’t say speed of light – just a significant fraction of it. Even 1% is extremely ambitious from an energy budget perspective. 10% or higher is probably achievable for small outbound probes using laser based acceleration – but they’ll just cruise by systems without any means to stop. For large “settlement” ships or similar, even getting 1% would be colossal amounts of energy (like percentages of the sun’s total output). So, yes, you’ll need to take the slow road.
Rogue planets come within a few light years of Earth. We could probably have a low speed, multi-generational ship to intercept one in a few hundred years. Once we’re on we’re hopefully good forever. Likely we’ll come close enough to some other interstellar bodies we could populate as we travelled. Exponential growth is bound to take off.
Yeah, if we aren’t in a hurry, and we can set up some fusion reactors and such on them and build whole civilizations on these rogue planets in the dark, it would work. Depends on how early and often we set up shop on passing planets, but in theory we could colonize much of the galaxy in a few revolutions around the milky way. So, under a billion years. ;)
I’m guessing if we’ve reached a level of tech to build a functional generational ship we would be patient.