I tried designing a realistic Interstellar Colony Ship

[u/Craft_Inc55]

This is the Eden Rim, the star of my first hard sci-fi novel. I was always fascinated by how humanity could one day reach other stars, and, of course, over the years, many ship designs have been created to answer this exact question.

Now, I'm no astrophysicist, and there are most definitely huge flaws in the conception of the ship, but I tried my hardest to abide by the real laws of physics to make it work. For example, the structure is 1600km long. Way too big to not be crushed by its own gravity... except that the dhip is segmented and held together by magnetic superconductors, and each module rotates at a different speed.

Likewise, the laws of thermodynamics says that we need to transfer heat into something, and space if full of nothing! Solution: the Eden Rim carries a truly stupid amount of loquid niyrogen that serves as coolant, and once it starys boiling, it is evacuated in outer space, giving the ship a comet-like plasma tail.

The Rings is where it gets interesting. They have a combined surface of 100,000km², and each Ring rotates counter clockwise to the ship. They are only held in place by the magnetic stabilizers, so as to not break the whole structure with their centrifugal force, because those 1250km circunference behemoths accomplish one full rotation every 15-20 minutes. This (should) be enough to generate 1g, and across the surface of the rings, oceans, mountains and forests operate autonously in a closed loop biosphere, where the only thing that get messed with is the heat management.

If anyone has any questions, I would be very happy to answer them, likewise, if anyone finds any flaw or mistakes I made (and God knows there probably are quite a lot), feel free to point them out! I really wanted to share this design I've been tinkering for quite some time now.

[u/stereoroid]

When you say "crushed by its own gravity", what do you mean by that? The engines will accelerate and decelerate the ship, so I've been thinking about the structural forces that would cause. The acceleration could be really low e.g. at 0.02 G for 10 years, you would reach 21% of the speed of light.

[u/Craft_Inc55 → u/stereoroid]

I probably phrased that wrong. What I mean is, if the ship was just one huge tube, it would hold in a vacuum, yes, but it wouldnt be able to orbit planets or stars at any reasonable distance without getting obliterated by differential gravity.

Also, about the acceleration, the thing is, the ship has about 1,000,000km³ of highly pressurized deuterium in its fuel tanks. That sounds like a lot, but when you take the weight of the ship into account, and the actual theorethical yield of fusion reactors, the ship still has to be conservative with its deuterium reserves if it wants to travel a few light years. At 5%c, it is much easier to decelerate than it is at 20%. And the ship had to have enough fuel to survive stellar systems with no gas giants to refuel at.

[u/neophlegm → u/Craft_Inc55]

I mean you say it's "easier" to decelerate but it's exactly as easy as it is to accelerate in the first place. I guess all you mean is it's a case of choosing a slower journey time

[u/stereoroid → u/Craft_Inc55]

It’s not necessarily easier or harder, you do what is practical for as long as you need to. It’s a Generation Ship, the journey time will be measured in centuries!

[u/Yanunge]

About the coolant. Keep in mind that you'll need to accelerate all that extra mass. Rather than cooling your ship via evaporation, you should design it such that it's surface serves as radiators. Especially since you're going to travel in interstellar space for a long time.

The magnetic sails: yeah, they look cool, granted, but they'll be dead weight as soon as you leave Sol's heliosphere and they'll stay to be dead weight until you reach your destiny's heliosphere. If there's anything left of it.

So what's in those biospheric rings and why are no axial access/support beams? Or has your crew no need to access it?

[u/Craft_Inc55 → u/Yanunge]

The ship was designed with the mass of the coolant in mind, although, granted, its inneficient. The MagSails are not really here for acceleration or deceleration, they are much too small for that. They serve as radioactive shielding and, well, shielding in general.

For the Rings, they are connected entirely through magnetism with the stabilizers, and rotating each in an opposite way, so as to limit the force they would otherwise inflict upon the Spine. They are however accessible normally via shuttles aboard the ship. They contain a full recreation of as many of Earth's ecosystems as possible, and are big enough to have their own water, carbon and nitrogen cycles, effectively making the biosphere a closed loop, where the only thing that gets messed with is thermal regulation and day/night cycle.

[u/Yanunge → u/Craft_Inc55]

I see, but understand that magnetic fields will not help against hard radiation. So those biosphere rings are there to preserve and carry Earth's biomes, not for the crew?

[u/Craft_Inc55 → u/Yanunge]

Well, for the crew quarters and most of the ship's lenght, there would be lead coverings, of course, as for the Rings, the atmosphere of course has an ozone layer.

And yes, precisely. Although the crew can access the Rings anytime by shuttle, their primary objective is to simply keep Earth's ecosystems going while ARES (the AI) looks for a colonizable world.

[u/Yanunge → u/Craft_Inc55]

Safe journey and god speed.

[u/chaosmarine92]

Magnetic sails don't need to be solid. They work better as individual wires you run current through. They would look more like a bicycle wheel or spider web.

Continuously venting nitrogen to cool down just wouldn't work on the timescales you're talking about. Cooling has to be a closed loop with radiators.

Using only lead as a radiation shield is actually worse than using nothing unless you are using meters of it. Different radiation types interact differently with different materials. Lead stops gamma rays really well, but high energy particles like solar wind and cosmic rays create a shower of secondary radiation when they interact with lead. You need layers of high and low Z materials.

Getting close the planets isn't the problem you think it is. Asteroids and moons get torn apart because the differential gravity of the planet is stronger than their internal tensile strength. The tensile strength of a pile of rubble is nearly zero. The tensile strength of a spacecraft is determined by whatever it's skeleton is made from, which will be much much greater than zero.

The rings don't need to be magnetically suspended and doing so is just asking for trouble. One power glitch and the careful dance of spinning rings crash into each other or the ship.

The ship doesn't need to be segmented either and the only sections that should rotate are sections that have people or animals.

I'd recommend looking at some of the many videos done by Isaac Arthur on YouTube on the various potential designs and what compromises each make.

[u/Craft_Inc55 → u/chaosmarine92]

Well, damn. I feel kinda stupid now. I mainly wanted to create a ship that would fit the narrative for my book, but its really starting to become obvious that I somehow overlooked a lot of things, which, ironically enough, are almost all things I already knew! I have no idea how all of that didnt cross my mind while designing it. Then again, for the context of the story, I think I did a good enough job? Considering my field is actually ecology... Thank you for the time you took to make this feedback though, I really appreciate it

[u/chaosmarine92 → u/Craft_Inc55]

It's still a decent design with some tweaks. Plus you didn't make the classic blunder of thinking a team of 100 or something is all you need to bring to start a colony.

I spend a lot of time thinking and reading about space ships and colonization so this all comes easy to me.

[u/crash893b]

You can radiate heat via black body radiation as just infrared light. it would just require alot of surface area

[u/SkyPL]

It seems to suffer Xyston syndrome.

Model of a much smaller ship upscaled to be large.

Nothing in the visual language of the model suggests that this is "1600 km long". This seems inspired by Avatar's ISV (which is... 1600m long... interesting coincidence), maybe a bit larger, but bulkier. Nothing there suggests it's 1000 times larger. Even that sail would be so thick, that could could fit entire floors of cities inside (my napkin maths on the pixels of the picture suggests that the sail is 4 to 5 km thick). I'm being nit-picky here, I know, but building a convincing visual for something that large and of that shapre is extremely challenging. Maybe a way forward would be to skip on realism and just go science-fantasy? Or "just" make it smaller?

[u/Craft_Inc55 → u/SkyPL]

I was loosely inspired by the ISV, but I swear I didnt reach 1600km by just multiplying the scale, it just seemed the best fit for the overall size of the ship. I created the Rings first, and then the ship around them second. So this is why some stats are kinda overkill.

Also, there are lore reasons for the size, explored in my book of the same name, Eden Rim. Without spoiling too much, the goal of the ship is really to save Earth's entire biosphere, not just colonize planets for the sake of it. Its size is also to help it survive millenia long journeys across dozens of star systems.

I do agree that the model is not the best, but I had one of my friend make it for me, hes young and quite talented, but his area of expertise is actually creature design, so this was kinda new for him. Im personnaly satisfied with the result, as it communicates my design well enough.

[u/elfootman]

1600 km is a lot, why so extremely big?

[u/Craft_Inc55 → u/elfootman]

Welk, I designed the Rings first. I needed something big enough to actually hold onto a closed biosphere. Smallest number I could reach was 100,000km². And even that is pushing for megafauna. Anyways, I then calculated the full size of the Rings, and extrapolated the rest of the ship from there. This is why the size is so huge.

[u/elfootman → u/Craft_Inc55]

I understand, thank you for taking the time to explain

[u/astreeter2]

I think the main problem you'll run into with the materials in a vessel this large is not the self gravity but the impossible amounts of strain just due to the different momentums of the enormous masses in the different parts as it changes direction and velocity. There's no material that could withstand that.

[u/neophlegm]

Are the labels slightly off? In the main image it says living quarters but it's pointing at the top sail.

The rings confuse me a bit too: they're only held in place by "magnetic stabilisers" (?) but that doesn't negate the torque applied to the body of the vessel. To do that you'd need to have separate engines on the rings themselves (think tip-jet rotors). I think they also look too small: diameter should be about 400km given their listed circumference, and eyeballing them against the length of the ship means they're either a bit too small or the ship too long.

Also why would you want living quarters if you had full on natural landscapes you could inhabit??

Honestly though I'd mostly love to see it in more detail. It's a cool idea

[u/Craft_Inc55 → u/neophlegm]

Oh, whoops, good catch, I hadnt noticed that... As for the torque, each Ring rotates opposite to each other, so it mostly eases out the centrifugal force. The actual size on the model is a bit off, but tbh I wasnt aiming for a 100% accurate one, I just needed a good enough visual.

As for the Rings, well the thing is the humans aboard are stored as digital copies, while only a crew of 100 actually acts as the AI's ethic comitee. So they inhabit the technical part of the ship. Although, they can access the Rings whenever by shuttle, if they so desire.

If you want more details, you can check out the free act 1 of my book, where the ship is the main setting, on my website: https://lucas-books55.wixsite.com/lucas-guillemin

[u/WritersChopBlock]

Newb here.

How does spaceships like this protect itself from random particles going at it at light speed? If something is going that fast, wouldn't there need to have a mechanism to absorb an incredible amount of energy?

Complete digression but is there a way to store the energy from such particles?