O'Neill cylinders, Stanford torus and Island One

Summary of what the thread established

• Comfort criteria. O'Neill chose the most conservative 1 rpm/1 g; later estimates put adaptation up to 10 rpm Paul451, 2015-10-08. O'Neill: >2 rpm causes problems for most people, 1 rpm for none daveklingler, 2015-02-23.
• Stability. Long-axis rotation is unstable, hence O'Neill's counter-rotating cylinder pairs Paul451, 2015-11-11. Long cylinders tumble through long-axis instability Paul451, 2025-10-19.
• Shielding. O'Neill used 5 m; even 1 m is not very effective in deep space lamontagne, 2022-11-01. Island One had a fixed, non-rotating shield Twark_Main, 2022-11-30.
• Material limit. Steel limits a Stanford torus to ~3.4 km diameter (forum lore); titanium to ~14 km radius whitelancer64, 2018-10-31.
• Economics. The 1974 Physics Today table was optimistic: $3M per colonist would need to drop to $300k; ~30 years per increment, so "we're one increment late" lamontagne, 2023-01-25. ~7 years of occupation to pay for food production lamontagne, 2022-11-15.
• Sources. The John Holt critique; the 1975 Summer Study ch. 4 shape criteria; the NSS settlement archive lamontagne, 2022-12-05. The 1975 study comparison missed the "scaled barbell" Twark_Main, 2022-12-07.
• Revival. Bezos (2019) popularized O'Neill cylinders mikelepage, 2019-05-14. The minimal O'Neill cylinder in The High Frontier: An Easier Way Habitant, 2025-10-17. A Stanford Torus rendering lamontagne, 2022-10-06.
• Critiques in the thread. A 100 m radius O'Neill with a 2 m moist-soil shield has enormous mass Aussie_Space_Nut, 2018-11-01. "O'Neill not near-term" Coastal Ron, 2025-10-17. O'Neill mass and energy are not doable this century Coastal Ron, 2023-03-02.

Open questions

• Which O'Neill assumptions (1 rpm, full shielding, lunar materials) still hold for first settlements?

Related pages

• Cylinders and spheres · Kalpana One · Habitant small O'Neill

Sources

Forum posts

• daveklingler, 2015-02-23 (reply #388, 1 like): O'Neill rpm. Post.
• Paul451, 2015-10-08 (reply #689, 1 like): O'Neill conservative. Post.
• Paul451, 2015-11-11 (reply #753): Counter-rotating pairs. Post.
• whitelancer64, 2018-10-31 (reply #1243): Material limits. Post.
• Aussie_Space_Nut, 2018-11-01 (reply #1250): Moist soil mass. Post.
• mikelepage, 2019-05-14 (reply #1635): Bezos. Post.
• lamontagne, 2022-10-06 (reply #1879, 2 likes): Rendering. Post. Attachments: torus.PNG.
• lamontagne, 2022-11-01 (reply #2300): O'Neill 5 m. Post. Attachments: solid_black_line_is_the_one_to_look_at.jpeg.
• lamontagne, 2022-11-15 (reply #2390): 7 years for food. Post.
• Twark_Main, 2022-11-30 (reply #2527): Island One fixed shield. Post.
• lamontagne, 2022-12-05 (reply #2550): Sources. Post. Attachments: figure4.21.gif, fig0808-stanford-torus-space-colony-design.gif.
• Twark_Main, 2022-12-07 (reply #2558): Missing scaled barbell. Post. Attachments: big_dumbell.png.
• lamontagne, 2023-01-25 (reply #3107, 1 like): O'Neill economics (1 like). Post.
• Coastal Ron, 2023-03-02 (reply #3452): Not this century. Post.
• Habitant, 2025-10-17 (reply #5010): Easier Way. Post.
• Coastal Ron, 2025-10-17 (reply #5011): Not near-term. Post.
• Paul451, 2025-10-19 (reply #5021): Long-axis instability. Post.

External references

• O'Neill, G. K. (1974). The colonization of space. Physics Today.
• NASA SP-413 (1977), Space Settlements: A Design Study (1975 Summer Study).