Talk:O'Neill cylinder

Ender's Game

I can find nothing to back this up. Anyone??? 68.107.83.19 05:06, 6 June 2007 (UTC)

I don't think it is correct. The battle school was an old bugger base. It was an asteroid with tunnels running through it and there were multiple game rooms. I thought I remember reading about antigravity, not a dead spot in the center. I'd say pull it.

O'Neill O'Neil

Which is it, O'Neill or O'Neil? Should this be moved? -- John Owens 06:47 May 2, 2003 (UTC)

Never mind, found the info, I'll fix it. -- John Owens

Where did Gilliland make his propositions? I can't find sources online. --NeuronExMachina 02:16, 16 Aug 2004 (UTC)

Gilliland wrote the Rosinante trilogy, which is set on a "mundito" in the asteroid belt. Excellent books, IMHO, and the design of the habitats is fairly fleshed out. He used a somewhat different design in another novel, The End of the Empire. However, I don't know what this:

"He also proposed structuring the habitat as a spiral wrapped on a central core. The advantage would be that much more area could be packed into the same volume, lowering the cost per unit area. A secondary advantage is that water would run downhill. Light would be distributed using light-pipes."

refers to. Some other story, or a misunderstanding?

—wwoods 00:39, 27 Aug 2004 (UTC)

Walls, No Roof, Centrifugal Force?

Is this kind of how it works? Or alternatively, is this how it could work, kind of like a very small ring world?

Some of the photos get me thinking of a structure without a roof, however they were intended. And, there's the part in the text that mentions the metal casing and the air (for the top side?) providing adequate protection from cosmic rays.

rama

Rendezvous with rama was published in 1972? - cohesion★talk 07:17, 22 November 2005 (UTC)

The list of science fictional uses

I've started improving this a little. I've put the items into approximate chronological order (some of them are in series that I'm not familiar with, so may have screwed up when within the series the habitats were introduced) to start with, and expanded the entry on Rendezvous with Rama to describe the similar placement of Rama's light strips to O'Neills windows, and indicate both its prior publication and likely independent origin.

I've also removed the reference to Greg Bear's Eon, which seemed somewhat far removed from an O'Neill cylinder, which is a very specific design, rather than the general concept of a rotating habitat. I'm in two minds about Babylon 5, but left it in. It is substantially more similar, but still feel it does not share enough of the characteristics of an O'Neill cylinder to be described as related to one. I wonder if JMS et al read any descriptions of O'Neills work when designing it? JulesH 17:14, 1 May 2006 (UTC)

Just my humble opinion: Babylon 5 certainly fits the model. I would define an O'Neill habitat as anything that's cylindrical and rotates for internal gravity. The mirrors are optional. A secondary definition would be that it replicates a natural ecology inside for life support. The quality of the CGI at the time really couldn't show it off but Babylon 5 was supposed to have hydroponics and gardens inside. The water resevoirs would also appear as lakes and could have been used for recreation purposes but were specifically left out of the design because JMS (show's creator) thought that he had a hard enough time selling the concept to the suits already. He mentioned in one of his RASTB5 usenet posts that the suits wanted to know how the crewmembers didn't fall off the ceiling. He said they had velcro on their shoes, deadpan delivery. The suits said "No, that's so impractical, how would they move around?"

If you can mention the other non-mirrored habitats here, you could certainly mention B5. Also, if such a habitat were built further out from the sun than earth's orbit, especially if it is used as the basis for an interstellar spaceship, there would have to be an internal source for light generation anyways. The mirrors could possibly be a cost-savings measure when the structure is parked near enough a suitable star.

8-24-06 by a humble non-registered user

"In the video game Halo, the Halo itself was a ring-shaped megastructure bearing some similarities to an O'Neill cylinder." If no-one has any objections, i would like to remove this... Halo is almost a ringworld, but certainly very different to an O'neill cylinder. WookMuff 07:04, 12 February 2007 (UTC)

Agreed. Halo, as the name suggests, was a ring world, not an O'Neill cylinder. See the Ring World article (which for whatever reason is specific to the novel of the same name, but still contains good information on engineering of such a construct). In the classical sense of the term, a ring world would be large enough to encircle its parent star, though the Halo was considerably smaller than this, in its own orbit at what we assume to have been a planetary distance, with its rotation exposing different parts of its interior surface to the incoming light over the course of its "day". Azriphael 15:17, 20 March 2007 (UTC)

It seems odd that the introductory paragraphs says that O'Neill cylinders were invented by O'Neill et al. in 1969, and then the O'Neill cylinders in science fiction section says that Heinlein used these in his 1941 story. Thus, either

• Heinlein's story did not describe an O'Neill cylinder; or
• O'Neill cylinders predate 1969 and were invented by Heinlein or someone even earlier; or
• Heinlein invented something similar to an O'Neill cylinder (in which case the intro paragraphs should make it clear that O'Neill merely revised earlier designs).

Therefore either this section needs to be retitled, or the intro needs to be rewritten, or both. — Lawrence King ^(talk) 03:25, 9 September 2007 (UTC)

Although this section of the article seems to have been deleted, if it is ever added again, a mention should be added of the Gundam series; I know that before I knew about the O'Neill cylinder, I thought I was looking at something from Gundam the first time I saw one. --Gero (talk) 14:05, 31 January 2009 (UTC)

clouds?

would clouds floating 1/2 a kilometer above the ground still react to the man-made gravity? Does the painting take extreme liberties?

Well, those are concept art so I do not know how real they can be. However, according to a normal reasoning process, a certain amount of debris, water vapour, etc. will float in the middle of the cylinder due to the weak gravity(actually no gravity). How far they can float from the middle is unknown. MythSearcher 03:01, 14 June 2006 (UTC)

Unless they was in the exact middle of the structure, they would still react to the "gravity" even by extremely small amounts till they sped up enough to be seen.

At about 900m from the ground, the gravity is only about 1/2G, and is way less than the gravity in which real clouds float on earth. MythSearcher^talk 09:46, 14 June 2007 (UTC)

The heat flow in a cylinder is crucial to the expected weather. If there is insulation in the cylinder walls, most loss of heat will be through the windows at night. Therefore, there will be wind at sunset and sunrise as the mirrors heat first one end, then the other end of the cylinder. The wind will go in twisted convection cells, sort of like Hadley cells on Earth. Clouds will form as moist air reaches the end that is currently the coldest. So, there will be fog, clouds and precipitation on the shaded cylinder end. Ray Van De Walker (talk) 02:04, 12 February 2019 (UTC)

Maximum size?

What would be the maximum size of an O'Neil colony if it were made out of carbon nanotubes?

Very, very large

To about 2,000 Kilometers in any direction from what I've learnt from the Feasibility section of the Globus Cassus article.

Are you sure about that? Is there any known material whose tensile strength is great enough to support a cylinder with a diameter of 2,000 kilometers at 1G??? --Antred (talk) 16:19, 15 September 2014 (UTC)

Assuming that one could make carbon nanotubes of any length, my calculations show that the design diverges at about 38km of radius. At that point, most of the material is supporting the simulated weight of the two cylinder halves, and the halves are quite thick (1.3? km), as well. It would probably be ridiculously expensive. The minimum size is more interesting. It's set by human factors, motion sickness. Relatively new research shows that it can be just a 100m of radius, and most people can get used to it. If it's put in a minimum-radiation orbit, low over Earth's equator, it doesn't even need a radiation shield. Ray Van De Walker (talk) 01:11, 12 February 2019 (UTC)

Link and comparison to Niven Ring?

Could a Niven Ring be maximum size of an O'Neil colony? Could an O'Neil Colony be made of current technology? Niven Rings are made of Scrith, a fiction material. Are O'Neil rings feasible? —Preceding unsigned comment added by 72.179.30.13 (talk) 18:39, 27 April 2008 (UTC)

No. A Niven ring maintains 1G, and circles a sun. Nothing known has a strength-to-weight ratio that can do that. Niven was assuming a material using nuclear forces in tension, and nobody knows how to make anything like that. Ray Van De Walker (talk) 01:14, 12 February 2019 (UTC)

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In Popular Culture

Why isn´t there a section like that? The "islands" in Gundam would be a prime example. --Lennier1 (talk) 14:20, 10 April 2009 (UTC)

This is mentioned in Space stations and habitats in popular culture. Wronkiew (talk) 14:30, 10 April 2009 (UTC)

Suggestions to expand

when i find the courage to do it - details of construction of the cylinder using materials from the moon (o neill) with specialised moon base.

- asteroid capture (o leary)

- using solar powerstats to finance the construction costs

- the proposal made to congress ( project independance), some details can be seen there http://space.mike-combs.com/SCTHF.html

- Curreri proposal to build them ( A Minimized Technological Approach towards Human Self Sufficiency off Earth - nasa ) using bolas and beaded habitats (same thing ?)

- interlink the articles with island one, stanford torus, powersats, moon colonization.

O'Neill cylinder in science fiction

I don't feel that the Halo franchise is a reasonable example of the O'Neill cylinder because the environment of the Halo world is more of a fantasy habitat for Aliens.

Probably the best use of the O'Neill cylinder was in the Gundam anime franchise where the actual colony itself was made popular in Japan. The cylinder was first shown in the original show Mobile Suit Gundam in 1979 and has been an iconic display of the Universal Century. The colonies have been separated in clusters within the Earth-sphere known as "Sides" and serve as provinces for the Earth Federation Government as well as Side 3 as an independent nation known as the Principality of Zeon. — Preceding unsigned comment added by 143.200.88.131 (talk) 23:45, 28 November 2012 (UTC)

Vague to the point of fantasy

What are the supposed/proposed materials of construction? What is the mass of the cylinder? What is the wall thickness? What justification is available for a "transparent" material capable of the required structural load? How would the wall (or window) be repaired? What about fatigue? Corrosion? Stress Cracking? Temperature variations? Aging/diffusion? Chemical/biological attack of the materials of construction by the ecology? Radiation damage? Meteor damage? Radiation shielding? How do you correct orbital perturbations? Has anyone associated with this page ever heard of engineering? how about quantitative data?173.189.74.9 (talk) 16:24, 27 May 2013 (UTC)

These are actually quite well established in the nss.org sources. Just gave a talk in the space museum last week. O'Neil got most of these covered with people from Stanford University and MIT over viewed different design aspects. —Preceding signed comment added by MythSearcher^talk 15:25, 28 May 2013 (UTC)

Steel. Millions of tons. About 50cm. Personally, I think it would be impractically expensive due to the expense of material to resist hoop stresses from the atmosphere. O'Neil had an alternative design called a "crystal palace" that is much less expensive. It's made of lots of little small, ~5m spheres or cylinders; the skin thickness for these is about a 0.5mm. It's glass, supported by frames. The stress is only 7psi/50kpa. By robots. It's not under dynamic load, so fatigue is negligible as long as it's below tensile yield. Corrosion is a live issue, unsolved as far as I know; A really good bet is to cover (evaporate, plate or flame-spray) the inside with a mm of asteroidal nickel, and then inspect it like a bridge. Like a bridge, it will have to be retired at some point. (This is another advantage of many small habitats- they go out of service more cheaply.) Stress-cracking? See Fatigue. There will be a fixed temperature gradient, controlled by the rotation and thermal radiation from the cosmic ray shielding. Aging and diffusion.. see retired. Chemical/Biological attack- see corrosion. Radiation damage is negligible compared to corrosion. Cosmic rays are energetic particles, but there are not many moles (chemistry...) of them. Orbital perturbations are fixed by momentum exchange; I expect active momentum trading, using tethers, mass-drivers, bags of tailings, cargo and money. *ahem*- O'Neil's classes -were- engineers. NASA has lots of references, see above. The exciting part of the proposal is that the best available engineers could not poke holes in it. Ray Van De Walker (talk) 01:35, 12 February 2019 (UTC)

A meteorite breaking a pane would cause loss of atmosphere, but wouldn't the very large volume of the habitat mean it was more of an emergency, rather than less? The air pressure would be like a volcano erupting. It would probably crack the walls.203.184.41.226 (talk) 03:17, 15 August 2013 (UTC)

The relative pressure difference will still be only 1ATM at max, and we are talking about metal or reinforced glass walls that are like 10~20m thick. —Preceding signed comment added by MythSearcher^talk 07:03, 15 August 2013 (UTC)

O'Neil was clever about the atmosphere, wanting to reduce the expense (nitrogen is rare and expensive in space), and prevent fires. He proposed (in High Frontier) pressure of a half atmosphere with 40% humidity (water is cheap), and a partial pressure of O2 and CO2 (relatively cheap) same as Earth to support plants and people. Ray Van De Walker (talk) 02:18, 12 February 2019 (UTC)

I assume that some people around here do not know what they are talking about. Let's do some very basic calculations for an Island Three design:

Length l: 32 km

Diameter d: 8 km

Thickness of wall: 10m (suggestion of MythSearcher, sounds a lot to me but considerung the diameter of the structure this is not that much)

Wall material Aluminum, density rhoAl: approximately 2700 kg/m3

Air density rhoAir: 0.6 kg/m3 (at half the pressure on Earth)

--> Total mass of space station: (d*Pi*l+2*(d/2)^2*Pi)*Thickness*rhoAl = 2.44E13 kg = 2.44E10 tons. That is 24.4 billion tons.

--> Total mass of air inside the pace station: ((d/2)^2*Pi*l*rhoAir = 9.65E11 kg = 9.65E8 tons.

Now let's assume that MythSearcher mixed up m and mm and let's recalculate with a wall thickness that is 1000 times less (although my gut feeling says that a thickness of 10 mm would be ridiculous for a structure of this size). The total mass would be 2,44E7 tons. That is 24.4 million tons.

Here are three facts:

- According to Aluminum the global production of aluminium in 2005 was 31.9 million tonnes.

- The payload capacity of a Saturn V (which is the biggest rocket ever built. It is not longer available since the mid-1970s) is about 120 tons into low earth orbit.

- The total mass of propellant for the first and second stage of a Saturn V is about 2500 tons.

Conclusions:

- Depending on wall thickness this project would require he total global production of aluminum of a period between 8 months and (correction:) 765 years

- Depending on wall thickness the required number of rockets of the size of a Saturn V to lift all the material in LEO is at least 203000 to at least 203000000.

- Without considering the mass of the pressurized gas cylinders you need 8 million Saturn V launches to fill the structure with air.

- Total mass of propellant for lifting all the aluminum and all the air into LEO would be between 20 billion tons and 529 billion tons.

Although I consider myself a space enthusiast: Such a project is absolutely impractible. It is not even at the point of fantasy, it is way beyond that. No single nation is able to provide funding. Not even a joint venture of all nations would be. The technology itself may be at hand but who is going to built millions heavy lift rockets? The resources available to mankind are very tiny compared to those needed.

Oh, I am certain that many readers will try to prove me wrong with their argument that all material needed would not be lifted from earth but shot into position by mass drivers based on the moon. But: How will all the equipment get to the moon at first (mining, smelting, manufacturing of parts, extraction of oxygen and other gases from moon rock, components for the mass drivers, ...) Do not believe this to be an easy task.

Best regards from Germany. 93.134.235.230 (talk) 22:22, 26 December 2013 (UTC)

To the guy above me who goes to great length to point out how utterly impossible all of this is. Yes, if you start from scratch, with no existing infrastructure and then go about building an Island-Three type habitat, then of course it's utterly impossible. Which is why O'Neill envisioned a totally different approach. The first thing he thought would have to be done was to establish a lunar mining colony (with a nuclear reactor for power supply) that would mine large amounts of building materials and basically catapult them into space where a prepositioned, small space station of some sort would "catch" the stuff and use it to build a very modest habitat vessel, as well as some solar generators. Then you'd gradually build more and more of these ... both habitat vessels and factory colonies. Then you'd use your growing industrial base to start building some larger colonies. Then ever larger ones, etc, etc. Island Three type habitats would be at the end of that process, not the beginning. Also, O'Neill wasn't stupid; he knew damn well that if all the material had to be lifted into space from Earth, the project would be completely impossible. That's why he only wanted to use rockets to get the material for the initial lunar colony and maybe the first few small space stations up there. Once that had been done, the rest of the material would have been obtained from asteroid mining, which has the huge advantage of you not having to lift stuff out of a major gravity well. Even so, it would obviously still have been an enormous undertaking, and at present humans are way too selfish, divided and myopic for such a massive project, but I do not believe that it would strictly be impossible for any technical reasons. --Antred (talk) 16:15, 15 September 2014 (UTC)

Please keep WP:TALK in mind. The article talk pages are for discussions in how to improve the article. If WP:RS are available for how the O'Neill cylinder is vague to the point of fantasy then I suspect people won't have any issues with a criticism section being added to the article. --Marc Kupper|talk 22:02, 13 December 2014 (UTC)

Linking to Elysium_(2012)

I don't know how to link specifically to Elysium_(2012), the movie. Anyone to teach/correct? — Preceding unsigned comment added by 84.25.253.61 (talk) 19:28, 23 September 2013 (UTC)

[[Elysium (film) |"Elysium"]] gives you "Elysium". The year was 2013, BTW. And don't forget to sign: ~~~~. TREKphiler ^{any time you're ready, Uhura} 23:07, 23 September 2013 (UTC)

What do the two cylinders look like?

I had trouble understanding how the two cylinders would relate to each other, and the pictures didn't really make it clear. At first I thought one inside the other, then I thought they might be at right angles, or parallel to each other (like fingers). Eventually I realised they must be like nunchucks but with a rotating joint instead of a chain. This article could really benefit from the use of the word "nunchucks" or some better explanation (or an image). --103.1.70.84 (talk) 19:49, 7 November 2014 (UTC)

I suspect they are closer to nunchucks based what's said in the Attitude control section of the article. I agree that a picture would be very helpful as I was wondering the same thing as 103.1.70.84. --Marc Kupper|talk 22:08, 13 December 2014 (UTC)

They're parallel, with the axes held in place by struts. One end of the cylinders aims at the sun. The struts don't have to be huge, because there's no weight. One strut pushes the ends apart, and the other pushes them together, to keep the sunward cylinder-end facing the sun by precession. Each cylinder has a length that's probably less than 10x its width. There's a real danger that the cylinders will buckle if they are made too long. How long is subject to design. Dirigibles have similar issues and are limited to <10x diameter. Hope that helps. Ray Van De Walker (talk) 01:45, 12 February 2019 (UTC)

Rama

I'm not an expert on space exploration, sci fi, or anything that touches upon this topic. But I'm puzzled that there is no mention of Clarke's Rama. Rendevouz with Rama came out before O'Neill's cylinder, right? I know that they're not identical, but I look at these illustrations, and I can only think of Rama. Unschool 18:15, 7 February 2016 (UTC)

No one has answered, so I'm going to go ahead and add some mention of Arthur C. Clarke. After all, this article states that the cylinder idea came out of O'Neill's class, but that was years after Clarke envisioned and published the concept. Unschool 20:41, 4 June 2017 (UTC)

Thank you

Yes Sir certainly. Thank you.LOBOSKYJOJO (talk) 03:06, 30 December 2018 (UTC)

Relevance of Bezo's suggestion

I'm sure plenty of people have come up with the same suggestion as Jeff Bezos, but I fail to see the relevance. No plans have emerged to do it, so it has had zero impact on the world so far. — Preceding unsigned comment added by 128.77.131.20 (talk) 12:12, 7 January 2021 (UTC)

Centripetal vs. Centrifugal

Moved from User talk:Bazza 7 § Centripetal vs. Centrifugal

I believe that the preexisting usage was correct. Centripetal force is towards the center, while centrifugal force is away from the center.

Centripetal

Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path. Isaac Newton described it as "a force by which bodies are drawn or impelled, or in any way tend, towards a point as to a centre.

Centrifugal

It is directed away from an axis which is parallel to the axis of rotation and passing through the coordinate system's origin. If the axis of rotation p]asses through the coordinate system's origin, the centrifugal force is directed radially outwards from that axis.

Note:Emphasis added.

Editor2020 (talk) 16:28, 17 February 2021 (UTC)

@Editor2020:Yes, I have read the articles already. The O'Neil cylinder article talks about how it implements artificial gravity; that article states that "artificial gravity, or rotational gravity, is thus the appearance of a centrifugal force in a rotating frame of reference (the transmission of centripetal acceleration via normal force in the non-rotating frame of reference)". It is the cylinder which is applying the centripetal acceleration, thus producing the reactive centrifugal force. As this is causing us confusion, and it not really within the remit of the cylinder article, I've been bold and removed it, leaving just the link to artificial gravity where readers can find out more if they wish. Bazza (talk) 16:57, 17 February 2021 (UTC)

I think that is a great idea. Editor2020 (talk) 01:47, 19 February 2021 (UTC)

Ringworld in the "[i]n fiction" section

Since the Ringworld isn't a cylinder, I'm not sure if it should be listed here. Could anyone please tell me if I'm wrong? (I haven't read the book, so please don't spoil anything for me.)--Thylacine24 (talk) 04:11, 17 April 2021 (UTC)

It's a ring, the size and position of a planet's orbit around a star, so no, it shouldn't there. Could be in "See also" though. Bazza (talk) 09:31, 17 April 2021 (UTC)