Elevators, spokes and internal transit

Moving people and cargo between the hub and the rim, and around the ring.

Key results

• Energy. A linear lift costs only ~500 J/kg per 100 m, regained on descent Paul451, 2015-03-31. Transit of 200–900 m takes 1–3 min Roy_H, 2014-02-20. Vacuum elevators could reach up to 1000 km/h on large stations Paul451, 2019-03-23.
• Balance.
• Elevators change the moment of inertia, so spin rate changes (the "ballerina effect"). In tethered designs they also curve the tethers dror, 2014-03-17. Roy_H: a ~1.05 g/0.95 g variation is acceptable Roy_H, 2014-03-19.
• Solutions:
  • Run two elevators 180° apart in unison Roy_H, 2022-10-04; Roy_H, 2014-02-16.
  • Software-controlled elevator counterweights Twark_Main, 2022-10-14.
  • Counterweight elevators in spokes: a 100 t Starship at 10 yd ↔ 10 t at 100 yd JohnFornaro, 2023-01-15.
  • Pump ballast faster than elevator transit lamontagne, 2018-08-05.
  • Move solar arrays on cables as counterweights mikelepage, 2014-03-18.
• Angular momentum is transferred to the hub when an elevator is plucked off; counter it with a hub flywheel Roy_H, 2014-02-20.
• Safety. Elevators on cables must be treated as crewed spacecraft; each move is a docking/undocking Jim, 2014-02-20. Provide ladders in the shaft lamontagne, 2018-08-06.
• A single elevator or dock is a redundancy issue Coastal Ron, 2022-12-04.
• Spokes: structure vs access.
• In a self-supporting ring the spokes are for access only lamontagne, 2023-01-19; Greg Hullender, 2022-10-04.
• Spokes act in simple tension with hub plates in shear, and are probably heavier than an equivalent circumferential beam lamontagne, 2022-10-13.
• A spoked torus has bending (load carried up to 22.5° to the nearest spoke) Twark_Main, 2022-11-11.
• Twark_Main: N ≥ 3 spokes is as stable as a disc or torus Twark_Main, 2025-10-25.
• Near-vacuum spokes (JohnFornaro) JohnFornaro, 2022-11-15.
• Peter_GST's "inside out" alternative: large modules as spokes, rim as a thin corridor Paul451, 2025-09-08.
• Climbing.
• Fireman's-pole descent is easy and climbing is hard; two-car counterbalanced lifts A_M_Swallow, 2015-03-14.
• Curved stair tubes are steeper near the axis ("Escher stairs") mikelepage, 2014-03-22; mikelepage, 2015-03-16.
• Other options: firefighter poles, railings, stair-lift chairs, a corkscrew slide lamontagne, 2023-02-03; LarryCanuck, 2023-01-30.
• Tethered stations: "can't climb" a tether KelvinZero, 2022-11-03.
• Circulating elevators move along the rim circle between opposite modules and keep g. Paul451 objects: they bring lateral hub loads, wobble and RCS fuel use TakeOff, 2015-03-30; Paul451, 2015-03-31.
• Tunnels.
• An inflatable ring tunnel between hab modules for walking, utilities and water circulation Paul451, 2015-03-31.
• A single transit tunnel/ladder is simpler than a full torus Lampyridae, 2016-01-08.
• A pressurized tunnel with a redundant elevator in the double-sphere barbell Twark_Main, 2022-12-04.
• Coastal Ron: a torus puts everyone on one floor (easy circulation, no elevators). A bola is "two office buildings joined by tunnel/elevator" with gravity reversal Coastal Ron, 2024-07-30.
• Elevator as vehicle. Elevators can double as excursion modules or escape pods lamontagne, 2022-11-03. A BEAM-based elevator car A_M_Swallow, 2015-10-23.
• Gym elevators. LMT's Terrestation: 1 g elevator gyms on booms at 8.4 m/s² and 75 m/s LMT, 2018-07-06.
• Coriolis on elevators. During radial transit the spokes push sideways; see comfort limits.

Open questions

• Is a minimum viable station acceptable without elevators, using ladders only? Coastal Ron, 2019-03-24
• What is the redundancy standard for hub–rim transit (two elevators, or elevator plus ladder)?

Related pages

• Mass balance · Transitions between g levels · Tethered bolas

Sources

Forum posts

• Roy_H, 2014-02-16 (reply #0, 7 likes): Two elevators together. Post. Attachments: Bigelow.png.
• Roy_H, 2014-02-20 (reply #82): Transit 1–3 min. Post.
• Jim, 2014-02-20 (reply #86): Elevators = spacecraft. Post.
• Roy_H, 2014-02-20 (reply #91): Elevator L to hub → flywheel. Post.
• dror, 2014-03-17 (reply #196): Ballerina effect. Post.
• mikelepage, 2014-03-18 (reply #201, 1 like): Solar arrays as counterweights. Post.
• Roy_H, 2014-03-19 (reply #205): ±5% acceptable. Post.
• mikelepage, 2014-03-22 (reply #245): Curved stair tubes. Post.
• A_M_Swallow, 2015-03-14 (reply #526): Fireman's pole; counterbalanced lift. Post.
• mikelepage, 2015-03-16 (reply #534, 1 like): Escher stairs. Post.
• TakeOff, 2015-03-30 (reply #544): Circulating elevator. Post. Attachments: rotator w elevator.PNG, rotator w elevator2.PNG.
• Paul451, 2015-03-31 (reply #560, 1 like): Linear elevator ~500 J/kg per 100 m. Post. Attachments: Station with ring.png.
• A_M_Swallow, 2015-10-23 (reply #723): BEAM elevator car. Post.
• Lampyridae, 2016-01-08 (reply #783, 1 like): Single transit tunnel. Post.
• LMT, 2018-07-06 (reply #884, 1 like): Elevator gym. Post.
• lamontagne, 2018-08-05 (reply #1158): Water balancing faster than elevator. Post. Attachments: water balance.jpg.
• lamontagne, 2018-08-06 (reply #1186): Elevators with ladders. Post.
• Paul451, 2019-03-23 (reply #1358): Elevators up to 1000 km/h. Post.
• Coastal Ron, 2019-03-24 (reply #1383, 3 likes): MVP may lack elevators. Post.
• Roy_H, 2022-10-04 (reply #1835): Two elevators in unison. Post.
• Greg Hullender, 2022-10-04 (reply #1841): Spokes non-structural. Post.
• lamontagne, 2022-10-13 (reply #2049): Spokes vs beam. Post.
• Twark_Main, 2022-10-14 (reply #2083): Software counterweight balance. Post.
• KelvinZero, 2022-11-03 (reply #2310): Can't climb tethers. Post.
• lamontagne, 2022-11-03 (reply #2312): Elevators as escape pods. Post.
• Twark_Main, 2022-11-11 (reply #2362): Spoked torus bending. Post.
• JohnFornaro, 2022-11-15 (reply #2388): Near-vacuum spokes. Post. Attachments: Ring-SK-007-Mars-Ring-&-Hub.jpg, Ring-SK-007-Mars-Ring-&-Hub.pdf.
• Twark_Main, 2022-12-04 (reply #2539, 2 likes): Tunnel with redundant elevator. Post. Attachments: russianBola.JPG, russianBola2.JPG.
• Coastal Ron, 2022-12-04 (reply #2540): Single elevator redundancy. Post.
• JohnFornaro, 2023-01-15 (reply #2909): Counterweight elevators. Post.
• lamontagne, 2023-01-19 (reply #2981, 1 like): Spokes for access only. Post. Attachments: can.png, can2.png.
• LarryCanuck, 2023-01-30 (reply #3193): Corkscrew slide. Post.
• lamontagne, 2023-02-03 (reply #3222): Poles, stair-lift. Post. Attachments: stairlift.PNG.
• Coastal Ron, 2024-07-30 (reply #4667): Torus one floor vs bola buildings. Post.
• Paul451, 2025-09-08 (reply #4937, 1 like): Inside-out: modules as spokes. Post.
• Twark_Main, 2025-10-25 (reply #5026): N ≥ 3 spokes stable. Post.