If you want to explore the history of generation ships in science fiction, you might start with a story by Don Wilcox. Writing in 1940 for Amazing Stories, Wilcox conceived a slick plot device in his “The Voyage that Lasted 600 Years,” a single individual who comes out of hibernation once every century to see how the rest of the initial crew of 33 is handling their job of keeping the species going. Only room for one hibernation chamber, and this means our man becomes a window into social change aboard the craft. The breakdown he witnesses forces him into drastic action to save the mission.
In a plot twist that anticipates A. E. van Vogt’s far superior “Far Centaurus,” Wilcox has his ragged band finally arrive after many generations at destination, only to find that a faster technology has long ago planted a colony there. Granted, Konstantin Tsiolkovsky had written about generation ships before Wilcox, and in a far more learned way. Fictional precedents like Laurence Manning’s “The Living Galaxy” (Wonder Stories, 1934) and Olaf Stapledon’s Star Maker (1937) imagined entire worlds as stellar wanderers, but we can give Wilcox a nod for getting the concept of generations living and dying aboard a constructed craft in front of the public. Heinlein’s “Universe” wouldn’t appear until 1941, and the generation ship was soon to become a science fiction trope.
We can hope that recent winners of the generation ship contest for Project Hyperion have produced designs that avoid the decadence and forgetfulness that accompany so many SF depictions. We do, after all, want a crew to reach destination aware of their history and eager to add to the store of human knowledge. And we have some good people working these issues, scientists such as Andreas Hein, who has been plucky enough to have led Project Hyperion since 2011. Working with the Initiative for Interstellar Studies, Hyperion has announced a contest winner that leverages current technologies and speculates in the best science fiction tradition about how they can be extended.
Hein is an energetic visionary, a man who understands that imaginative forays can help us define key issues and sketch out solutions. The winning design is reminiscent of the kind of space habitats Gerard O’Neill advocated, a 58-kilometer multi-layered cylinder dubbed Chrysalis that offers space enough for Earth-like amenities such as grasslands and parks, art galleries and libraries. The notion includes animals, though only as a token of biodiversity in a culinary scene where vegetarianism is the order of the day.
Interstellar Necessities
What intrigues me about the Chrysalis design is that the need for cultural as well as physical survival in a society utterly closed off for centuries is emphasized. Thus Chrysalis offers habitable conditions for 1,000 people plus or minus 500, with care to ensure the handing off of experience and knowledge to future generations, critical both for societal health as well as the maintenance of the ship’s own technologies. This presumes, after all, the kind of closed-loop life support we have yet to prove we can create here on Earth (more on that in a minute). Gravity is provided through rotation of the craft.
Chrysalis is designed around a journey to Proxima Centauri, with the goal of entering into orbit around Proxima b in some 400 years. And here we hit an immediate caveat. Absent any practical means of propelling something of this magnitude to another star at present (much less of building it in the first place), the generation ship designers have no choice but to fall back on extrapolation. As in the tradition of hard science fiction, the idea is to stick rigorously within the realm of known physics while speculating on technologies that could one day prove feasible. This is not intended as a criticism; it’s just a reminder of how speculative the Chrysalis design is given that I keep seeing that 400 year figure mentioned in press coverage of the contest. We might well have said 600. Or 4,000. Or 40,000.
Image: Chrysalis, the Project Hyperion winner. Credit: Project Hyperion/i4IS.
Like the British Interplanetary Society’s Daedalus starship, Chrysalis is envisioned as using deuterium and helium-3 to power up its fusion engines, with onboard power also fed by fusion generators within the ship. The goal is 0.01C with 0.1G acceleration during the acceleration phase and deceleration phase. As to cruise, we learn this about the fusion power sources that will prove crucial:
All Chrysalis power generators consist of toroidal nuclear fusion reactors housed in the hull frame structure and the habitat axial frame structure separating the various stages. The multiple redundancy of the generators for each shell and each stage guarantees a high tolerance to failure in the event of the failure of one or more reactors. The D and He3 liquid propellant is contained in the propellant tank units located in the forward and after interface propellant bays of the habitat module…
Inside Chrysalis
What would it be like to live aboard a generation starship? The Chrysalis report is stuffed with images and ideas. I like the concept of structures designed around capturing what the team calls ‘generational memories.’ These appear to be tall, massive cylinders designed around what can only be called the aesthetics of worldship travel. Thus:
Each treelike structure hosts multi-story and multi-purpose environments [such] as halls, meeting rooms, and other kinds of infrastructure used by all the inhabitants as collective spaces. There are enough of these public environments to have redundant spaces and also to allow each generation to leave a mark on creation (paintings, sculptures, decorations, etc) for future generations…
The Chrysalis slide show makes it tricky to capture the extensive interior design in a blog format like this, but I advocate paging through it so you can blow the imagery up for a closer look at the included text. As with some of the O’Neill concepts, there is an almost idyllic feel to some of these vistas. Chrysalis is divided into five sections, and within each section there are levels that rotate to provide artificial gravity. The report refers to Chrysalis as a ‘biome ark,’ saying that within each stage there are two shells for dedicated biomes and one for agricultural food production.
Here, of course, we run into a key problem (and readers of Kim Stanley Robinson’s novel Aurora (2015) certainly get a taste of this conundrum). Let me quote the Chrysalis report, which describes ‘controlled ecological bio-regenerative life support systems (CEBLSS)’:
Through a controlled ecological BLSS all chemicals are recycled and reused in a closed loop ecosystem together with a circular bio-economy system in which all organic wastes from the living environments are reintroduced and composted in the agricultural soils.
The acronym nudges the idea into credibility, for we tend to use acronyms on things we’ve pinned down and specified. But the fact is that closed-loop life support is as big a problem as propulsion when it comes to crafting a ship made to sustain human beings for perhaps thousands of years. The Soviet BIOS-1 and subsequent BIOS projects made extensive experiments with human crews, succeeding with full closure for up to 180 days in one run at Krasnoyarsk, while in the U.S., Biosphere 2 ran into serious problems in CO2 and food production. As far as I know, the Chinese Yuegong-1 experiments produced a solid year of closed ecological life support, although I haven’t been able to verify whether this system was 100 percent closed.
Daily Life Between the Stars
So I think we’re making progress, and the Chrysalis report certainly lays out how we might put closed-loop life support to work on the millennial scale. But all this does make me reflect on the fact that we’ve spent most of our energies in interstellar studies trying to work out propulsion, when we’re still in the early days when it comes to onboard ecologies, no matter how beautifully designed. In the same way, we know how to get a payload to Mars, but how to get a healthy crew to the Red Planet and back is still opaque. We need a dedicated orbital facility studying both near and long-term human physiology in space.
The Chrysalis living spaces are made to order as science fiction settings. Interior walls can be functional screens producing panoramic views from Earth environments to overcome the spatial (and psychiatric) limitations of the craft. The inhabitants are given the capability of continually engineering their own living spaces through customizable 3D printing technologies so that the starship itself can be seen as evolving as the crew generations play out their lives. Individuals are provided with parks and gardens to enhance privacy, no small consideration in such a ship. The authors’ slide show goes into considerable detail on ecology and sustainability, social organization and mental health.
In a lovely touch, the team envisions a ‘Cosmos Dome,’ a giant glassy structure where the plenary council for the mission would transact its business. One gets a goose bump or two here, reminiscent as all this is of, say, the control room in Heinlein’s Orphans of the Sky. Burst in there and you suddenly are reminded of just where you are, with Sol behind and Alpha Centauri ahead.
How exactly to select and train a crew, or maybe I should say ‘initial passenger list,’ for such a mission? The Hyperion team’s forays into sociology are curious and almost seem totalitarian. Consider their Antarctic strategy: Three or four generations of crew will live in experimental biospheres in Antarctica…
…to select and monitor all the characteristics that an interstellar population should have. In addition, the creation of a strong group identity and an almost tribal sense of cooperation among the generations of inhabitants is intended to enhance the inter-generational cooperative attitude of the future Chrysalis starship population.
If I’m reading this correctly, it presupposes people who are willing to consign their entire lives to living in Antarctica so that their descendants several generations along can get a berth on Chrysalis. That’s a pretty tough sell, but it emphasizes how critical the suppression of conflict in a tiny population can be. I’m reminded of John Brunner’s “Lungfish,” which ran in the British SF magazine Science Fantasy in 1957 (thanks to Elizabeth Stanway, whose “Journey of (more than) a Lifetime” covers generation ship fictional history well). Here the descendants have no interest at all in life on a planet. As Brunner says:
These had been children like any other children: noisy, inquisitive, foolhardy, disobedient…. And yet they had grown up into these frighteningly self-reliant people who could run the ship better than the earthborn any time they put their minds to it, and still refused to take the initiative.
Definitely an outcome to be avoided!
Language and Stability
The Chrysalis team describes their crew’s mental stability as being enhanced by many reminders of their home:
Chrysalings will also be able to take walks within the different terrestrial biomes of Shell 1 to be in contact with natural elements and plants of the terrestrial biosphere. In Shell 2 there will be opportunities to do concerts, experience theater activities, access ancient Earth materials (books, art objects, etc.), make crafts and other handmade hobby activities. Shell 2 is the real beating heart of the society, where people come together and can freely co-create new cultures and ideas. Thanks to the use of recyclable materials with which the buildings were constructed, residents can also decide to recreate new architectural forms with different shapes and spaces more suitable to their cultural style.
I think the linguistic notion here is quite a reach, for the team says that to avoid language problems, everyone on board the spacecraft will speak a common initial artificial language “used and improved by the Antarctic generations in order to render it a natural language.” And a nod to Star Trek’s holodeck:
The inhabitants may also occasionally decide to meet in simulated metaverses through a deep integration system for cyberspace…to transcend the physical barriers of the starship and experience through their own twin-avatar new worlds or simulations of life on Earth.
Image: The people behind Chrysalis. Left to right: Giacomo Infelise (architect/designer), Veronica Magli (economist/social innovator), Guido Sbrogio (astrophysicist), Nevenka Martinello (environmental engineer/artist), Federica Chiara Serpe (psychologist). Team Chrysalis.
Anyone developing a science fiction story involving generation ships will want to work through the Chrysalis slide show, as the authors leave few aspects of such a journey untouched. I’ve simply been cherry-picking items that caught my eye out of this extensively developed presentation. If we ever become capable of sending humans and not just instruments to nearby stars, we’ll have to have goals and aspirations firmly fixed, and compelling reasons for sending out an expedition that will have no chance of ever returning. Just defining those issues alone is subject for investigations scientific, medical, biological and philosophical, not to mention the intricate social issues that humans pose in closed environments. Chrysalis pushes the discussion into high relief. Nice work!
Despite a century of scientific and technological progress since the first generation starship was mooted, we humans 1.0 still assume that our apex position in the cognitive realm on Earth means that our meat bodies will be the form our species travels to the stars. With the space colony concept, humans living in Earth-like conditions could be transferred to a starship design, and Project Hyperion maintains that viewpoint. And yet…
Asimov’s robot stories had robots working where humans could not, including testing the first hyperspatial starships. Much later, when retconning the robot universe to the Foundation universe, Asimov presages the issue of why no robots are in his galactic empire. Asimov invokes a conversation between his detective, Baley, and the Auroran chief roboticist, Amadiro, about whether humanoid robots should settle the galaxy first to make it perfect for human settlement. Baley indicates that the flaw is that the humanoid robots will think of themselves as human and resist biological humans from taking over.
But do these human futures make any sense given teh technology trends that are clearly in view today? Why would huge starships like Chrysalis be the first to explore and settle new worlds? The need to bring a large chunk of Earth along shows the problem. Which worlds would be suitable for terraforming to allow human takeover? Can we know in advance without sacrificing humans to find out? In a sense, these living generation ships are the modern version of Noah’s Ark, bringing all the life along that is needed to ensure human survival, to later [partially] terraform an exoplanet like the mountain top appearing as the seas ebb on the flooded Earth. Instead of a mere 40 days, the generation ship needs 250 years before it reaches land after cruising the seas of interstellar space.
We are probably within a century of AGI. Not within the “real soon now” hype of the big AI companies, but also not in the “AGI will never happen” camp. A large disk drive can hold the neural weight matrix of the current frontier AI models, and let’s assume that technology will both increase the size of the models to that of the equivalent of a human brain in architecture and connections. Use that as the template to drive any number of physical robots of any form. The starship needs no biosphere or structure to maintain rotation or radiation shielding. The ship will be far smaller and simpler, needing just the propulsion mass. It may be small enough to have a beamed sail accelerate it to cruise velocity, and its own propulsion to decelerate. Any suitable world can be settled by the ship. The fabrication technology would allow more robot bodies to be built and given independent brains. There should be no competition between any indigenous and terrestrial biologies. No need to prepare a suitable habitat in advance for a human crew. Robots will certainly be damaged and need repair, but the resources to construct new ones, whether inorganic or organic, will be readily available. “Life support” will be little more than attaching an electrical power source.
Any human crewed starship will only arrive much later, if ever. Robots will be our avatars to explore and exploit resources. Given the tools and instruments (or perhaps just their designs for local fabrication), the robots could do all the scientific work we would do.
Terrestrial knowledge and technology will advance while the robotic ship is in transit. That knowledge can be transmitted to the ship, as could newly trained AIs, ready to use it immediately when the mind is embodied.
A machine-based starship, therefore, is smaller and cheaper. Its payload is not burdened by life support, nor the need to ensure stability and a sufficient breeding population to reach the destination. The robotic ship avoids all the problems of maintaining a human environment for the journey. Rather than building a ship that dwarfs the Titanic, a fully outfitted robotic ship may not need to be huge, with the propulsion system chosen being the determining scale factor.
If we must have humans along, if we have AGI-level robots, then we probably can manage to use seed ships, where only the target generation needs to be grown and nurtured to the required age on arrival.
Given the huge scope of the resources needed, not to mention the ethics issues of a generation ship, I find it almost inconceivable that a robotic ship would not be the first to go, and be fast enough to easily keep ahead of any future human-crewed starship using generation ship technology as outlined in this competition.
Just as robotic probes have largely usurped human space exploration of the planets, so robots will be our interstellar explorers.
Interesting design however I think no one is likely to build these multigeneration ships, too many resources required, no one nation would be able to build it alone. Better options would be to put the crew into cryosleep or send robots first however at the end of the day the mission should be to send humans to habitable exoplanets. I’ll be covering these issues including realistic and practical options for interstellar travel here if anyone is interested (LinkedIn article under construction):
https://www.linkedin.com/pulse/advanced-propulsion-resources-22-paul-titze-su26c/
Cheers, Paul.
The generation ship is definitely one of the most interesting ideas in speculative science and science fiction. Also one of the less creative, since it doesn’t consider if relativistic ships or sleeper ships or life extension technology would be more practical.
You need a good industrial base with you for tool making.
We got too used to weak little Delta II rockets and the concept of utility fog was born.
You need these grand visions.
It is said that Margaret Meade once remarked that the ultimate purpose of anthropology was not the understanding of existing human cultures, but the ability to devise new ones.
Looking through this material convinces me that the construction of human cultures suitable for interstellar exploration will be much more difficult than solving the problems of propulsion, engineering and navigation.
There are also ethical issues involved here. What if the crew (or their descendants!)
decide at some later time that they want no part of the enterprise? They won’t have the ability to just turn around and come home.
The only analog I can think of for this sort of social engineering is the military. We have spent a great deal of effort programming adolescent men to submit to the rigors of combat, with only limited success. And keep in mind that even that activity is considered temporary by the participants. No one fighting a war is convinced that he will not survive it, or that he will die of old age long before the conflict is decided.
I served on a man-of-war in a combat zone for over a year, and even though I was never in any physical danger or otherwise afraid for my safety, and I truly loved being at sea and the work I was doing, if I had been told I would be doing that for the rest of my life I would have mutinied on the spot.
I can’t think of any voyage in Earth history that would compare with the mission we are discussing here. The only one I can think of that even comes close is the first circumnavigation by Magellan five centuries ago. Only one of his three ships, and less than a score of his initial crew of 270 survived.
Even if it were possible to select and train a crew to do this, and construct a social structure that would keep them together and survive multiple generations, I sincerely doubt we would be able to get it to work the first time we tried it.
Orphans of the Sky was my first leap into interstellar travel, but I had forgotten that it was to Proxima Centauri. “A brief prologue states that after launching in the year 2119, the Proxima Centauri Expedition, the first attempt at interstellar travel, was lost and its fate remains unknown…”
I was also surprised to discover that Heinlein’s novel, Methuselah’s Children, which features a group of people hijacking a starship, served as the inspiration for Paul Kantner’s album “Blows Against the Empire.”
Reminiscient of Clarke’s “The Songs of Forgotten Earth” and Hogan’s “Voyage From Yesteryear”. I agree there’s a lot of work yet to do before a successful robot flyby, an (Expletive) load before seedships can be contemplated and a larger amount than those before a generation ship. Some of those developments may have valuable terrestrial applications.
Gerry O’Neill’s 2nd space book, “2081: A Hopeful View of the Human Future,” included using the knowledge of self-sustaining space colonies on Earth. In particular, the idea of city arcologies that circumvent the local climate. We may need such approaches sooner than we think.
While I expect it will prove to be easier and cheaper to put interstellar voyagers into some kind of hibernation (or saved on a disk), there is one huge unwarranted assumption in this article: why do we assume the ship will be culturally isolated?
Sure, they can’t have real-time conversations with people back on Earth, but they can still get transmissions. They will still have access to all of human civilization’s cultural creation during the voyage. A delay of months or years in transmission isn’t very different from the communication lags between European states and their colonies in Earth’s age of sail. Australia didn’t collapse into decadence just because they were getting back issues of the Illustrated London News.
IDK if cultural transmissions from Earth will help. It didn’t help the current nations like Haiti and the Sudan from disintegrating, or the rise of authoritarian governments within the past century.
OTOH, how do isolated remote tribes fare over the long term? Do we know?
This is all fine. But I still think they suck as a concept. Perhaps its because I’m spoiled by living in the Western U.S. However, it might appeal more to people who have grown up in O’Neill style habitats through out the solar system.
Pretty much the same argument that O’Neill and his followers suggested. Space colonies first to build societies, then at some point, some of them would head for the stars.
Generation ships might be more appealing to East Asians, who are used to living in large, densely populated cities such as Tokyo and Hong Kong. Visiting friends or going on holiday means getting on a space craft to travel from one habitat to another, presumably in the Saturn system. Its kind of like living in Tokyo where you get on a plane and go to Hong Kong or Singapore. These are the kind of people who would live in O’Neill habitats and, later, generation ships to go to the stars.
I have always been fascinated with the concept of generation ships since becoming aware of them thanks to Robert Heinlein and his novel Orphans of the Sky — even though I think they will only be invoked either by people who cannot wait for FTL propulsion or if evacuating Earth and/or the Sol system is required before we have a fast means of interstellar travel.
I also question whether such a project would be allowed to happen at all: If Earth and therefore humanity are in imminent peril, how will the so-called authorities build even one generation ship without mobs of people who know they won’t be on them coming to either destroy the project or force their way onboard, which would also doom the effort?
Will it have to be built in secret somehow, say on the far side of the Moon? Yet would such a thing be possible without an extensive industrial and settlement infrastructure already set in space?
Even if a generation ship is built in a time of relative peace, who will be able to do this and who will get to go? Will the rich and powerful once again get to have it all and leave the rest of us in the dirt?
And where will they go? Will an alien planet as a destination work? Or should they just wander the galaxy, stopping at various star systems to refuel, replenish, and sight see? So many unanswered questions and dilemmas.
This site has links and discussion on various landmark generation ship SF stories, including “The Voyage That Lasted 600 Years” by Don Wilcox…
https://classicsofsciencefiction.com/generation-ships-in-science-fiction/
More here:
https://sciencefictionruminations.com/sci-fi-article-index/list-of-generation-ship-novels-and-short-stories/
https://turingchurch.net/a-history-of-generation-ships-in-science-fiction-e9326388a397
Very intricate proposal. I may follow with more comments, but a few miscellaneous points initially.
I may have missed something related to these points. The format is not conducive to quickly scanning over the whole proposal much less term-searching the whole proposal. At least I don’t know a way to do that, and clicking back and forth and back . . . through 41 fairly intricate slides looking for something specific was labor intensive. And I typically use such full-document means – whole-document scanning and term-searching – to ensure as a final matter that I didn’t miss something on a particular point before commenting. Yes, things are basically grouped topically, but it’s hard to be sure that I haven’t missed something by assuming it wouldn’t be in a particular set of slides addressed to topics that are seemingly unrelated in my mind to the point I’m looking back for.
Subject to that . . .
● Agricultural Redundancy.
If there’s one system that absolutely can’t fail, it’s the agricultural system.
(Well, OK, one of many that absolutely can’t fail.)
I’d split production between two independent agricultural shells. With the production from just one being minimally sufficient in a pinch for baseline survival if the other fails for one reason or another.
Redundancy on critical systems of course should be at a premium in a voyage such as this.
● Some . . . Agricultural Non-Automation.
I see references in the proposal to a lot of robotic automation for agricultural production.
Over and above that being one more thing that can break, hands-on agricultural work would seem to be just the thing to help keep people from going nuts in a confined artificial environment.
And also keep them trained in skills that they may need at the destination.
If they actually make it, they’re going to need to be able to grow crops, etc. even if robotic systems fail. And also adapt their agricultural expertise to the local terrain.
Perhaps AI will be able to do all that for them by then (I remain skeptical). But – as a general overall matter – preserving the capacity for human innovation across those generations may be the most key difference between surviving and not.
The last thing I would want my sustenance to depend on is: “Well, maybe try rebooting the system again.”
● Gravity.
If you’re accelerating/decelerating at 0.1 g, how does that more or less gravitational force interact with the artificial gravitational force supplied from rotating an internal structure?
Does the artificial 1 g from rotation wholly negate or override that otherwise 0.1 g in an orthogonal direction?
Or does that 0.1 g in force at least have some impact on the mechanics and engineering of the rotation infrastructure, as a perturbing force putting an additional tangential mechanical stress on that infrastructure?
And what about the planned 0 g spaces? How does that 0.1 g affect those spaces?
Not my field, so those are my layperson questions du jour.
● Genetic Defects from Inbreeding.
Well, along with these.
After basically eschewing marriage, monogamy, and an explicit family structure in a small population of only 1500, how do they avoid inbreeding and the associated genetic issues as the collective-raised children grow up, hook up, and apparently procreate fairly willy-nilly (subject to population control limits)?
When you look back at early religions, like all those rules in Leviticus in the Old Testament, it looks like a lot of the rules favoring marriage and then also prohibiting people from “laying” with certain other people were designed to prevent inbreeding.
What’s the strategy to prevent that in the social structure they advance? Or are they just accepting the risk of genetic issues along the way? Like with some of those confined communities on Earth where inbreeding occurs basically as a matter of course.
● Looking Forward Rather Than Back.
There’s discussion of employing imagery from life on Earth, albeit likely highly curated imagery given other parts of the proposal tending to essentially isolate and insulate the society from traditional Terran influences, past, present and future. But in any event relying on looking back to Earth imagery as some sort of calming or unifying measure.
If I’m in a big tube permanently heading away from an Earth that I’ll either never see again or for later generations never have seen and never will see, I’m not fully sanguine as to how calming, unifying, etc. abundantly recurring images of life on that Earth will be.
It might be perhaps better to focus more on imaginings of what life will be at the destination. The ultimate why of being in that big tube in the first place.
May just be me, but I’d rather look ahead rather than being constantly reminded of what I or my ancestors left behind and never will see again. While making the current habitat as Earth-like as possible, such as the trees and the like.
Contrast the situation with that of a crew on a long duration mission inside the solar system that eventually will return to Earth. Dreams of home have comforted many a sailor on a long voyage.
But if you’re not ever going home . . . .
George King commented on August 13, 2025 that these proposals, while impressive, are definitely hard to get through easily. Not that the details aren’t impressive or appreciated, but you really need a good outline / summary to show the key points of these plans and what makes them stand out and potentially successful.
I am sorry but those mission statements do not cut it. And Hyperion should point out at the top of their page or make a dedicated one linked to their main page bringing readers in who want the details. I guarantee you that the average viewer will gloss over and skip these proposals due to being so jam-packed with information – some of it in very tiny print.
You also do not want the media outlets distilling these proposals for you. At best they will miss the key points and at worst they will distort the actual information present due to ignorance and their deadlines.
If you really want people to get excited about flying humanity to the stars via this method, you need to present it in a way that will grab and keep them. Then you can get into the nitty-gritty for those who want to know more. Otherwise we will have another one hundred years of pretty graphics presentations on how one day we will fly to Alpha Centauri and beyond – while the public will keep expecting Star Trek warp drives.
I can offer my services as a writer who knows the sciences in this regard, but to be blunt, I do not work for free, nor should anyone.
While I am here, there is this previous Centauri Dreams piece on comparing the building of a generation ship to the construction and purpose of Roman Catholic Cathedrals of Medieval Europe:
https://www.centauri-dreams.org/2020/07/17/the-cathedral-and-the-starship-learning-from-the-middle-ages-for-future-long-duration-projects/
There is also this project from almost two decades ago, the Ultimate Project. This plan makes the Hyperion efforts look positively FTL in comparison:
https://www.centauri-dreams.org/2008/06/18/the-ultimate-project-to-the-stars/
https://www.centauri-dreams.org/2008/02/26/the-ultimate-project-10000-year-journey/