Life in an O'Neill Island 3 cylinder

[Swindle1984]

eion, you're incredible. I love how you dismiss space habs as being expensive and inefficient, then proceed to tell us how the obvious answer is to alter the atmosphere and temperature of an entire planet as well as alter its rotation, because clearly that's easier than launching some shit into orbit and assembling it.

[eion]

eion, you're incredible. I love how you dismiss space habs as being expensive and inefficient, then proceed to tell us how the obvious answer is to alter the atmosphere and temperature of an entire planet as well as alter its rotation, because clearly that's easier than launching some shit into orbit and assembling it.

Um, I never said they were too-expensive or too-inefficient to be built. I said that BOTH will likely be built because both have advantages, even if the extent of the groundside habitat is a mining camp to ship building materials up a space elevator to the orbital construction site of the final habitats.

You do not have to choose between the minivan and the sports car, you can have both because both do different jobs well. In fact, let's quote me just so it's clear:

It is an immature mind that thinks that either space habitats or planetary colonization are a silver bullet, or that we only have the time, money, or inclination to only do one or the other; in fact we may have to do both.

Don't assume that just because I'm arguing with Des that I must be taking the polar opposite position to him. Groundside habitats might well be a transitional stage in human colonization of the solar system. Whether they come at the beginning or somewhere in the middle is unclear, but a civilization able to build mega structures (Think Ringworld, Culture Orbitals, etc.) Would likely have no need to lock themselves into an inefficient gravity well like a planet, and will likely have long ago disasembled any useful planetary material for other uses. Now a less mature civilization may find advantages to groundside living.

And for Mars at least (the most likely candidate for terraforming because it is DAMN easy to do there) there's no need for fantastical technologies or even an alteration in its rotation because, and this'll be the third time I've said it in this thread, its day is ONLY 30 MINUTES LONGER THAN EARTH'S.

[LionElJonson]

Don't assume that just because I'm arguing with Des that I must be taking the polar opposite position to him. Groundside habitats might well be a transitional stage in human colonization of the solar system. Whether they come at the beginning or somewhere in the middle is unclear, but a civilization able to build mega structures (Think Ringworld, Culture Orbitals, etc.) Would likely have no need to lock themselves into an inefficient gravity well like a planet, and will likely have long ago disasembled any useful planetary material for other uses. Now a less mature civilization may find advantages to groundside living.

I dunno; even if the mass would be better spent in habitats, I expect that there'd be plenty of people who'd object to you disassembling their home, and possibly ecological protesters if it's a life-bearing planet.

[eion]

Don't assume that just because I'm arguing with Des that I must be taking the polar opposite position to him. Groundside habitats might well be a transitional stage in human colonization of the solar system. Whether they come at the beginning or somewhere in the middle is unclear, but a civilization able to build mega structures (Think Ringworld, Culture Orbitals, etc.) Would likely have no need to lock themselves into an inefficient gravity well like a planet, and will likely have long ago disasembled any useful planetary material for other uses. Now a less mature civilization may find advantages to groundside living.

I dunno; even if the mass would be better spent in habitats, I expect that there'd be plenty of people who'd object to you disassembling their home, and possibly ecological protesters if it's a life-bearing planet.

It probably wouldn't happen all at once, but slowly over time, or one might argue that a society with access to launch loops, space fountains, and other low cost launch methods might not care about the additional costs of groundside living.

If you're designing from scratch, habitats make a great deal of sense. As Des has pointed out, you have total control over every aspect of them: space, gravity, illumination, etc. But so rarely does the final state of something emerge without any transitional forms. As he has pointed out, it really comes down to whether you want to ship people there or bring building materials here. I've pointed out that people are self-replicating, and have assumed that solar colonization would follow established trends in human colonization efforts. Namely, a small seed force is sent that establishes a foothold, utilizes local materials to establish the first colonies, multiplies to increase its workforce, and transports back desirable materials to the parent country.

In the near-term, groundside habitats seem to offer a better chance at establishing a self-sustaining colony sooner than an orbital habitat. It is of course possible that my reasoning is colored by the fact that no independent orbital habitat has been established, but several groundside ones have (aside from the oxygen needs that is, those come free on this planet), and that it is possible to test every aspect of groundside habitat living here on planet Earth.

I see this whole debate as one between the perfect and the good, between iterative steps and final destination.

[eion]

It could be either "I" or "My faithful robot". And in space habitat construction you'd have propellant costs plus zero-gravity-labor costs, which are always higher.

Why? It'd probably be higher for man, but not necessarily for remote controlled machines.

Perhaps, but some procedures will still require someone to go out, at least in the near-term.

The downside is your habitat mirrors will have more mass, since they must be bigger. The mirrors are very thin aluminum foil though, so their mass isn't a lot. O'Neill's Pluto number Terralthra mentioned isn't strictly an upper limit - that's just the point where the mass of the mirrors required exceeds the mass of the rest of the habitat! If you had infinite mass, you could go even further out.

At the main belt, the mass of the mirrors goes to about 10x that of at Earth. But at Earth, the mirrors have super small mass - the page you posted earlier put them at about 300 units, compared to about 10 million units for the whole hab, a tiny, tiny fraction. 3,000 / 10,000,000 is still a small fraction of the mass cost, so the asteroid belt works just fine.

That makes perfect since for illuminating the habitat itself, but I guess I have questions regarding illuminating the farm cylinders and powering the station itself. Is some of the light reflected by the mirrors used for solar-thermal heating to power the station?

I've never really read O'Neill's proposals in full, obviously I need to, but if memory serves he thought the demand for solar power satellites would fund the construction of the habitats, and the cost of those facilities must surely increase the further out you build them.

Yes, everything in a hab-farm is controllable, but that also means everything MUST be controlled.

That's not really hard. When the ecology problem is solved, you can set it and forget it. Inertia keeps it rotating, life finds a way.

We've yet to establish a small scale self-sustaining ecology. Biosphere 2 failed. There may be a lower limit for enclosed ecologies. This is definitely something that demands further research because it's a problem for smaller orbital and early groundside habitats.

[Junghalli]

Guys, if you're worried about the energy costs of moving stuff around why not just build a space habitat on top of a rich asteroid or comet? You can get much or all of your materials from the asteroid, and you still have all the advantages of a space habitat in terms of access to space, essentially zero gravity environment, being able to customize the gravity to your liking etc.

If gravity is required, a centrifuge can provide it, without necessarily connecting to the main habitat cylinder.

Plus I don't see any reason you couldn't just attach industrial facilities to the outer wall of the habitable cylinder if that was desirable. That way you'd have very easy access between the habitable and industrial zones while still effectively exporting all the dirty stuff to outer space.

Even if you could house as many people on each of them, you're still talking somewhere on the neighborhood of 30 billion max population. Say Venus too. 40 billion. Whereas habitats are functionally limitless in their capacity to expand and house the human race.

What are these figures derived from? Surely not simple surface area. At 40 billion people a planet like Earth would have an average population density of a mere 78 people per km^2. By contrast, Italy has more than twice that population density. Even Mars, with roughly 1/4 of our surface area, would have only ~300 people per km^2 with that population.

[Terralthra]

Italy is also a net food importer. If the entire human population lived at a density such that everywhere was a net food importer, where exactly is food going to come from? 10 billion is a fairly middle-of-the-road estimate for the Earth's carrying capacity - estimates vary from less than 1 billion all the way up to 30 billion - and putting each of the other terrestrial planets and the moon at equal population is if anything, a fairly aggressive estimate.

[Junghalli]

Italy is also a net food importer. If the entire human population lived at a density such that everywhere was a net food importer, where exactly is food going to come from? 10 billion is a fairly middle-of-the-road estimate for the Earth's carrying capacity - estimates vary from less than 1 billion all the way up to 30 billion - and putting each of the other terrestrial planets and the moon at equal population is if anything, a fairly aggressive estimate.

I don't think you can extrapolate carrying capacity for space and hostile environment habitats from carrying capacity for a civilization like ours exploiting a natural biosphere. They're pretty different systems. A better bet would be determining how much land is needed to support 1 person with high density techniques (greenhousing, hydroponics etc.) of the sort a habitat would probably use, and then calculating from that.

Personally I suspect a civilization that could support huge numbers of people in habitats could fill a planetary surface much more densely going by that. But I haven't run any math so that's fairly worthless.

Of course this is ignoring very important factors like minerals and volatiles. Which would probably favor space habitats, as most of the heavy elements in asteroids hasn't sunk to inaccessible planet cores and there should be plenty of volatiles available in comets.

[Crossroads Inc.]

Any math people out there know an easy way to "unroll" the inner space of an O'Neil Cylinder for planning out the isnides? Its easy enough to unroll a cylinder, but getting the size right has been bothering me as I have been trying to get it to scale.

What I hope to do eventually is "unroll" a Rama Cyclinder cause I was curious about just how large a space, in terms of cities or geographic features, could fit into it.

[Sarevok]

Are you talking about calculating the internal surface area of a Rama cylinder ?

[Junghalli]

Already done in the beginning of this thread:

The surface area of a cylinder is the circumference times the height*. We know the height (or length), 24 km. O'Neill's original plans called for a height of 20 miles (32 km) and a diameter of 4 miles (6.4 km) (link). The circumference of a circle with a diameter of 6.4 km is 20 km. For a 24 km long cylinder this is an area of 482 km^2. For the 32 km cylinder it would be 460 km^2. The inner surface of the colony would be the equivalent of a 24 X 20 or 32 X 20 km rectangular plot of land. From the illustrations, perhaps half that appears to be habitable land area and half appears to be windows. I'm not sure about the ends, assuming an actual cylinder I doubt they'd be habitable (IIRC they should be sheer cliffs under the centrifugal gravity) but the illustrations seem to suggest a tapered end which I imagine makes more sense.

Relevant equation is circumference of a circle:
2TTRadius = Circumference

* That should be the surface area of the sides of the cylinder. Assuming the ends are flat circles their area would be TTRadius^2.

[Swindle1984]

I'm glad I get to hang out with a bunch of nerds who know what the hell they're talking about, because I barely passed college algebra and never took physics. I'm still trying to figure out what the fuck laser wavelengths and the electromagnetic spectrum have to do with chemistry.

[Crossroads Inc.]

Thanks for the math guys, thats a huge step toward what I am after.

I think for a lot of us, it is hard to come to gripes with the sheer massive scale of a full fledge cylinder. I myself didn't really appricate it until I saw this painting:
When you look down and first realize you really could fit a full city into just one small end of an O'Neil Cylinder, it really boggles the mind.

Even the Rama animation, showing the entire island of Manhattan inside it, makes it hard to grasp the enormity of the size until you zoom in really really close and realize how much space there ins there.

[Swindle1984]

Thread necromancy is allowed so long as it's for a legit reason, yes?


I have more questions to help flesh out the story (which I've begun writing).

1) I have the main character, a visitor from Earth, docking at one end of a cylinder. To reach "ground level" they are descending a ramp. It starts out in micro-gravity, and gravity gradually increases as they get closer to the land strip inside the cylinder wall. Is this accurate, and would it be a reasonable means of getting from the dock to the "ground", or is impractical for any number of reasons (including distance, which could be finagled as having the dock not at the exact center of the cylinder cap).

2) There are ultra-light aircraft in the cylinder for recreation and transportation; how difficult would it be to simply fly from one land strip to another? Just how dangerous would an aircraft be if it stalled and crashed, considering the rotation of the ground below it? Could an aircraft in the center of the cylinder essentially float there indefinitely thanks to microgravity, so long as they compensated for wind?

3) How scarce would uranium be for the space colonists, if they have access to Luna, Mars, and the belt? How difficult/time consuming would obtaining it be compared to simply buying it from Earth?

4) Similarly, what about essential vitamins and minerals such as potassium? Would the colonists be able to obtain everything they need to survive from space, or would some have to be imported?

[Junghalli]

Building aircraft might be a lot easier than on Earth - once you got into the weightless center of the cylinder you wouldn't have to fight gravity just to stay aloft. Surface or subsurface railways and roads would probably be easier as a main method of transport though. It'd probably take less energy and be less demanding in terms of engineering and you're not talking about a really huge land area. I could see air travel being mostly recreational.

A hanging train running on a railway on the underside of a space habitat would be pretty cool. It'd probably be a lot easier to just run it inside a tunnel or inside the habitat, but think of the view this way!

As far as elements humans need to consume, I'd think they'd probably be fairly common ones. After all, life evolved to use stuff that was naturally relatively readily available on Earth's surface, and Earth and the asteroids originally formed out of more or less the same material.

[Ford Prefect]

1) I have the main character, a visitor from Earth, docking at one end of a cylinder. To reach "ground level" they are descending a ramp. It starts out in micro-gravity, and gravity gradually increases as they get closer to the land strip inside the cylinder wall. Is this accurate, and would it be a reasonable means of getting from the dock to the "ground", or is impractical for any number of reasons (including distance, which could be finagled as having the dock not at the exact center of the cylinder cap).

Just have a series of luxurious funiculars that run from the spaceport down to the surface. To have them actually walk down a ramp would be ridiculous: could you imagine having to descend a mountain every time you got off a plane, with your luggage?

[Junghalli]

That'd be hard. At the ground level, you'd have full gravity; you're talking a real airplane there. To fly a simple airplane, you'd have to go up... then back down, so the gravity is still a problem, and it is more distance anyway!

To some place on the opposite side of the habitat it might be a shortcut. It'd be the difference between crossing a circle along the diameter and crossing it along the circumference.

I wonder if it would be possible to build elevators from one side of the habitat to the other to provide such shortcuts? They'd need to be housed in 8 km tall towers. Although most of the tower's length would be in reduced gravity conditions, so that might make it easier.

Question about that sloping area at the end of the cylinder that was mentioned earlier: what could that surface area be used for? It seems a pity to waste it. Intuitively I imagine that it would be rather like building on a huge hillside where the gravity gets lower as you climb it, am I wrong?

[Ford Prefect]

Question about that sloping area at the end of the cylinder that was mentioned earlier: what could that surface area be used for? It seems a pity to waste it. Intuitively I imagine that it would be rather like building on a huge hillside where the gravity gets lower as you climb it, am I wrong?

It depends on how you build your interior, but you basically have hills towards the end. Put the idea into the heads of the populace that low gravity manors are the height ofl uxury and that's where the upper class starts paying zillions for space.

[Junghalli]

It depends on how you build your interior, but you basically have hills towards the end. Put the idea into the heads of the populace that low gravity manors are the height ofl uxury and that's where the upper class starts paying zillions for space.

Think of the view you could have from a house up there!

[jollyreaper]

Yeah, I've always considered the habitats (at least the insides) to be primarily for living and non-industrial type work. Industry can be on the outside, or even a dedicated platform nearby, especially if your doing zero g manufacturing.

Those vids were cool but yeah, having conventional downtowns and office towers is not how these things would work. I had to laugh at some of the other ideas in different Gundams where the interior of the habs were represented by essentially 20th century Japan transplanted into space.

Babylon 5 was working on a smaller budget and couldn't do as much but had a more accurate representation of what these habs would be like. The surface interior is for recreation, living, and enjoyment. The serious stuff is "underground."

The one thing I can't quite wrap my brain around is how the buildings would be handled. These habs are a hundred or more years in our future. While the way humans would want to live shouldn't change all that much, how we achieve it could be quite different. Humans will want comfortable houses on a human scale, something comforting and familiar. But the real question is "What are these people needed for?"

If I were in the early 20th century writing science fiction, I might have read about geologists discovering oil deposits in shallow water and postulate that there could be oil in deep water. I could then imagine that in a hundred years there could be vast floating cities to support the drilling efforts, offshore boomtowns. The oil platforms we have in reality don't even exactly compare to a wild west boomtown, let alone something like New York on the high seas. Machines do most of the work, there's just not a need for so many people.

The Air Force had plans for manned spy stations up in space with spacemen operating the spy telescopes. This whole idea got scrapped when they realized that spy satellites could accomplish the same task, cheaper and unmanned. The humans who operated the equipment could do so from the ground. If we did try to build an array of solar power sats, something O'Neill figured might be a good cause for building habitat cylinders to house all the workers, we'd probably just teleoperate all of the equipment from the ground. There would be a minimal need for having humans on-sight up there.

So, if we did build these habitats, what for? What would the people be doing inside? What's the rationale?

[Guardsman Bass]

So, if we did build these habitats, what for? What would the people be doing inside? What's the rationale?

I can think of a couple reasons. If you wanted good access to space resources, you're not living at the bottom of a gravity well. You can make the internal environment of the cylinder more or less whatever you want, and rotate it for whatever gravity you want (and what your structural materials want). If you have some major space infrastructure, this allows people to live closer to it in greater comfort (particularly if your cylinder isn't located near Earth).

[jollyreaper]

Those vids were cool but yeah, having conventional downtowns and office towers is not how these things would work.

That's not a given. This is probably just your bias talking - your brain thinks "spaceship = volume limited must be efficient = underground stuff" but neither of those equals are actually true.

I can concede that. Maybe if there's enough area they could do all sorts of things. But there would certainly be a continuum between practical space colonies where efficiency is required and spectacular god-tech colonies where there are no limits.

So, if we did build these habitats, what for? What would the people be doing inside? What's the rationale?

Whatever they damn want.[/quote]

On a far enough timeline, we can posit god-tech and whimsy is as good a rationale as any. But in a near-term timeline, one that's within our ability to consider and anticipate, what would be our reason for going to space and building these things? How does society justify the expenditure to itself? I'm not talking about matters of technical feasibility, I'm talking political feasibility. Technically speaking, we could probably have wheel space stations like from 2001, moonbases, and a manned mars mission by now. We lack the political will which is why we haven't made it happen. The Apollo Program was not something a wealthy individual could have bankrolled -- it was a major undertaking by a super-power and required the political will to make it happen. Without the Cold War, without the Russian bogeyman, it never would have happened.

I freely admit that I might be suffering from a limit of imagination but I'm having a hard time coming up with hard science and hard economic justifications for us developing a significant manned presence in space. Romantically I'm all for it. Space is awesome. But I can't really come up with a justification that I could take to the bank for financing.

Now once we already have people up there, everything can change. We see that happen in history all the time. Some great undertaking is made, the original goals might not be met, but it paves the way for something new. European monarchs sponsor colonies in the Americas expecting gold, they don't get the gold but the colony takes on a life of its own. Brits sentence prisoners to transportation to Australia, eventually the Commonwealth gets a new country. Rather unexpected.

So, what's the political rationale for building giant space habs and how would they look?

[jollyreaper]

So, if we did build these habitats, what for? What would the people be doing inside? What's the rationale?

I can think of a couple reasons. If you wanted good access to space resources, you're not living at the bottom of a gravity well. You can make the internal environment of the cylinder more or less whatever you want, and rotate it for whatever gravity you want (and what your structural materials want). If you have some major space infrastructure, this allows people to live closer to it in greater comfort (particularly if your cylinder isn't located near Earth).

By that same token it would make sense that we would have large seafloor habitats for our drillers to live in, the people working the deep-sea oil wells. Makes sense to be closer to the work. But so much of it ends up done remotely via bots.

So, your basic argument seems sound -- people working in space would like a nice place to live. But what would require people to be in space? What sort of resources are we talking about? Asteroid mining, orbital manufacture, something else? What sort of thing would require people to be there directly and not teleoperating the machines from Earth?

[jollyreaper]

Just as a general thing, the simple explanations don't seem to hold up. One of the classics is going into space to relieve the population pressures on Earth. But if it costs a million bucks a head to put up space habs, then it would make more financial sense to pay couples a half million to only have one kid.

[sirocco]

If we're talking of extra-solar O'Neill cylinders it makes sense too.

1- we don't know if FTL is possible and 2- it seems that there are more giant gas planets than Earth-like planets out there. So building a space station would be a sound solution at first. And as population frows, it may evolved into an O'Neill Island cylinder or maybe another original design more efficient.

And in our own solar system?

The most sensible idea is that mining/research sites will evolve into full-fledge colonies. People may have various reasons for going there. But I think you can't use the analogies of drilling stations in the middle of the ocean because essentially are still on Earth, breathing the same air and drinking the same water, under the same gravity that everyone else. They can easily be evacuated if there is problem. While up there, we are talking about complex procedures that would require a lot of time for travel and safety procedures (to avoid radiation over-exposure and bone fragility).

So you will need at least a few people with adequate skills, which means that the salaries will be pretty high. That will increase the appeal of your space stations. At some point, the workers will notice that salaries are not that good compared to the job or that their bodies won't bear the trip back to home and that they'll need to become actual settlers. Or they just would want to stay there.

This is just one of many scenarios about what might happen.