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What's the Minimum Number of People for a Generational Ship to Proxima Centauri?
- joeblow9999 8y ago2
- elif 8y agoi think they mean to have a human colony, not to have a creepy incest cult.
- WJW 8y agoIf you don't care about long term viability, one person would already be sufficient.
- Analemma_ 8y agoNo. Contrary to the sci-fi trope you occasionally see crop up, you could not make a sustainable human population starting from two people. The inbreeding would render everyone sterile (and probably severely physically and intellectually disabled) after just a couple generations. The actual number in the paper is 98, and even that probably wouldn't be a very healthy population of humans. Around 600, with significant initial diversity, is the number I've seen tossed around as the minimum number for a genetically healthy population.
- IpV8 8y ago0. Just have a robot incubate some clones once it gets there.
- crooked-v 8y agoThis gets you a bunch of feral children who die after unintentionally breaking something essential for life support.
- lainga 8y agoNot if Anne Hathaway's there to raise them.
- stcredzero 8y agoThe world will be scary when we get to the point where we can implement an Anne Hathaway bot that's not in the uncanny valley. The world will be even more frightening when we have the beta Hathaway bots and they're still in the valley.
- lainga 8y agoNo, I meant actually sending a series of clones of Anne Hathaway, each of which raises another clone of Anne Hathaway until the target planet is reached. The first generation would, of course, be the actual Anne Hathaway.
- IpV8 8y agoGood point. We'll need to send some robot mothers too.
- crooked-v 8y agoThat gives you step -1 of "invent general-purpose AI that can completely replace a human". If you've got that, why not just send the robots by themselves?
- TooBrokeToBeg 8y agoWhy not just send rocks? The concept is the migration of the species, ie the fulfillment of genetic imperative. If you aren't interested in that, the rocks will be fine without us.
- paulpauper 8y agoyeah instead of taking rocks from space, send rocks into space lol
- yawz 8y ago> If we would create a spacecraft right now, we could only reach about 200 km/s, which translates into 6300 years of travel. Of course technology is getting better with time and by the time a real interstellar project will be created, we can expect to have improved the duration by one order of magnitude, i.e. 630 years. This is speculative as technology as yet to be invented. This is the dilemma that should make us really consider and possibly wait for the right technology. Otherwise it is quite possible to arrive to destination and find it populated for millennia.
- ohjeez 8y agoThere have been at least a few SF stories built on that premise. It's driving me nuts that I can't recall which they were.
- scandox 8y agoIn Homesick by Lyn Venables the first interstellar crew arrive home and find that people have been lapping them for 30 years. That’s 1952. Probably it was already a trope by then...
- jgroszko 8y agoAlistair Reynold's Revelation Space universe explores this, often times with sub-light travelers arriving at what they thought would be one of the largest cities in known space only to find it devastated by a plague. More relevantly, the book Chasm City, set in this universe, explores a set of generation ships competing to arrive first at an uninhabited planet.
- DanBC 8y agoI think Allen Steele's Coyote series features this, but I can't seem to find any reference to it. (And I no longer have the books).
- deepspace 8y agoKim Stanley Robinson's Aurora comes to mind, as it explores similar ideas to the study. The featured generational starship suffers from a deteriorating biome due to inbreeding and loss of nutrients, and the book also explores the effects of disasters and politics on the viability of such a journey,
- squirrelicus 8y agoCan't wait to see perspectives on this one. I looked into this years ago and remember finding the number to be around 150-300 if you centrally plan reproduction (and no, you don't want an unequal gender distribution). Also that cheetahs experienced a population bottleneck of this magnitude and so we have some data on what it looks like. Take that with a grain of salt, memory and amateur research are finicky.
- natch 8y agoThe idea that the travelers need to be people as we know them today is a huge assumption that should be jettisoned. As we improve medicine and merge with AI, we should expect other changes to be possible, not just brain interface changes, but also body changes. Essentially we are still a version 1.0 and the iterations to new versions haven't even started yet... but these should be well underway in the timeframe of starting voyages to other stars. Even for Mars, much closer obviously, we should think about whether it's easier to change body types in the medium term than it would be to terraform Mars to a desirable level.
- crooked-v 8y agoYou might like the Behrooz Wolf books by Charles Sheffield. The main scifi gimmick at the core is complete bunkum, but the books do a lot of exploration of extreme adaptations of the body for various environments, including other planets and the vacuum of space.
- stephengillie 8y ago> ...we should think about whether it's easier to change body types in the medium term than it would be to terraform Mars to a desirable level. This could be called bioforming[0][1] and here's an abstract for a paper that suggests modifying humans, alongside modifying Mars, to speed colonization.[2] [0] http://memory-alpha.wikia.com/wiki/Bioforming http://memory-alpha.wikia.com/wiki/Bioforming [1] http://terraforming.wikia.com/wiki/Bioforming http://terraforming.wikia.com/wiki/Bioforming [2] https://www.researchgate.net/publication/289486325_Bioforming_and_terraforming_A_balance_of_methods_for_feasible_space_colonization https://www.researchgate.net/publication/289486325_Bioformin...
- mevile 8y agoHaving a child that is bound to live their entire life on such a ship strikes me as tragic and depressing. I don't think I could personally be responsible for creating a life in that kind of environment. I'd hope we'd get the quality of life possible in space very high before we ever attempt any kind of thing like this.
- crooked-v 8y agoIt seems to me like the only reasonably ethical way to do it would be to have a small city's worth of people (a small city's worth of living space) and thus "society" rather than "crew". But that runs into the organizational problem that a society that's lived in space for two or three generations may not want to deal with this messy, disease-ridden, gravity-encumbering planet business again.
- reificator 8y agoWhich brings up a much overlooked issue regarding colonization efforts: antibodies and the human immune system in general being exposed to an alien environment after generations of sterile space travel.
- majewsky 8y agoColonizable planets will either: 1. be sterile, meaning that this is not a concern. (The only germs that settlers will run into are those they brought with themselves on the ship.) 2. contain alien germs, in which case no humans would have antibodies for them regardless of origin or travel speed.
- reificator 8y agoSure, but I know people who are just allergic to metals in jewelry. Maybe it's germs on it, but if it's not...
- jerf 8y agoI think that's actually the primary problem with this idea. If all you have is a crew that can live on their ship, and they arrive at Alpha Centauri... now what? Terraforming on anything even remotely resembling a useful time frame is a massive undertaking. Literally in this case, requiring both substantial mass, and energy in enough quantities that it is reasonable to use mass-based measurements to quantify it! They're far more likely to just sidle up to an asteroid loaded with useful things and start using the local resources. But if you're going to do that, there are useful asteroids waaay closer than the next star system over. Interstellar colonization makes some degree of sense, but not until we're pretty far along exploiting the local system. It's not something even our great-grandchildren are actually going to do while there's so many resources here. But, eventually, if humanity and its descendants keep growing, eventually it makes sense. And rather than cobbling together something that can just barely make it and then do nothing, by then they'll have the infrastructure to make many ships, and give them useful things that will actually be helpful at the other end. And they may even be able to build "bridges"; if space really is full of ice planets we can't see, those make fantastic bases for launching and deceleration lasers, and if you can use those, the economics suddenly start looking a lot more practical. And I'd point out that barring a lot of very enormous coincidences, other planets aren't going to be "disease-ridden". If anything has to worry about being "disease-ridden", it's the ship they're on, not the almost-certainly sterile matter on the other end.
- stevecalifornia 8y agoTLDR: "Moore concluded that a 200 year-long mission should have an initial crew of 150 – 180 people. (...) Among other results, it was found that an initial crew of 14000 – 44000 members is well-optimized to ensure healthy offspring, even in the case of a sudden disaster occurring once during the mission. According to his study, a crew of 150 people would always be on the verge of extinction in the case of a large-scale catastrophe." https://arxiv.org/ftp/arxiv/papers/1708/1708.08649.pdf https://arxiv.org/ftp/arxiv/papers/1708/1708.08649.pdf I had to go to the linked study to get the answer. If an article posits a question in the title...it should answer it in the body. Hopefully in the first paragraph.
- RodgerTheGreat 8y agoAssuming you can cryogenically preserve sperm indefinitely, it seems like you could simply stock the ship with a large supply of frozen sperm gathered from distinct males and use this stockpile exclusively for reproductive purposes. As long as you have enough sperm samples there is no risk of inbreeding. Frozen sperm should, at any rate, consume far fewer resources than male colonists for an equivalent supply of genetic variety.
- cimmanom 8y agoMaybe freeze some eggs too. Might be worth having some variety in mitochondrial DNA.
- bilbo0s 8y agoBut the problem is sending people AT ALL. Not really which people you send. The women you send there would still have the problem of potentially arriving to their destination to find it has been populated by humans for millennia. (If they arrived at all. Interstellar space is a dangerous place.) It would be anticlimactic in the extreme to arrive to a destination to find a thriving civilization thousands of years ahead of you in terms of technical know how.
- mitchtbaum 8y ago> But the problem is sending people AT ALL. Right. It doesn't seem to me that humans can live outside of Earth's safety for any significant duration of time at all. The Sun is very explosive.
- deleted 8y ago[deleted]
- mygo 8y ago> It would be anticlimactic in the extreme to arrive to a destination to find a thriving civilization thousands of years ahead of you in terms of technical know how. That would be extremely exciting! IMO even more exciting than finding a desolate planet. Discovering an entire unknown civilization is anti climatic? No way, it would be like discovering Atlantis! So what if they’re more advanced? We were capable and curious/brave enough to even make the trip! Keeping score would be pointless but the fact would remain that we made first contact with them, on their turf, even though they were more advanced.
- bmcusick 8y agoInteresting discussion, but not very forward-thinking on the biology side. As a simple critique, they claim that 32 crew would result in too much inbreeding, but what about IVF? There's no reason all the children have to be the full children of the crew. They could put sperm and egg cells from thousands of donors into deep freeze before leaving. There's also no discussion of life extension, which seems more near term than interstellar starcraft. Anyway, we will probably have good data on the optimal size of asteroid colonies long before interstellar colonization is a live issue.
- drb91 8y ago> There's also no discussion of life extension, which seems more near term than interstellar starcraft. So long as we’re comparing unknown unknowns, we might as well throw fusion and GAI in there.
- paulpauper 8y agoit's pretty fascinating how just 98 can sustain a colony for 6000+ years
- coldacid 8y agoActually it sounds like they're targeting the 600-700 year journey.
- cfadvan 8y agoThis is asking the wrong question. We don’t know how to create a robust artificial biosphere, we don’t know how to shield such a large ship from radiation efficiently, we don’t know how to maintain or create the human microbiome, because we’re nowhere near understanding it. We’re so far from being able to survive off of Earth that we don’t even know all of the challenges that exist. Even if we had the propulsion, which we don’t, we’d still be screwed.
- true_tuna 8y agoCold sleep?
- ninetyEight 8y agoAnswer: 98
- rurban 8y agoThat's not even a multiple of 42
- Comevius 8y agoThe worst thing about spaceships is that they are easy to destroy. Hard times create strong men. Strong men create good times. Good times create weak men. Weak men create hard time. This social dynamics would not go well on a generational ship.
- BrandoElFollito 8y agoTL;DR: 98 people. With 32 the chances of success drop to 0% I thought the number would be 10-50 times larger.