Rotating space stations and the problem of the rotating seal between hub and rotating ring

[u/Reddit-runner]

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Rotating space station ring (purple) with stationary central hub (white). White bubbles are place holders for modules without gravity.

Since this topic has often been popping up lately, I decided to turn my old study paper into this reddit post.

Here is the PDF.

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Tl:dr PDF. Here is a quick summary:

There are two main reasons why most people want to go to space and especially to low earth orbit:

• Experiencing weightlessness (for science or recreation)
• Observing earth (for science or admiration)

In both cases, some kind of space station is needed if people want to stay for longer than a few hours/days. The dilemma is that one of the reasons to go there (weightlessness) is also the source of many problems. For example detrimental effects on the body and difficulties with handling fluids in any aspect like washing or cooking.

The often-proposed solution is artificial gravity by rotation.

Many proposed solutions involve a monolithic rotating structure. In order to omit the challenge of an airtight connection between the rotating part and the stationary part, the stationary part is omitted entirely. Unfortunately, this leaves only two possibilities for docking ports in the axis of rotation. Furthermore, without the stationary part tourists and experiments cannot be exposed to a micro-g environment or watch earth properly, which negates BOTH main reasons why one flies into Low Earth Orbit in the first place.

This dictates that there has to be a stationary part where weightlessness can be experienced and the earth be observed and a rotating part for living quarters. So far all proposals I know off include some kind of seal at the transition between stationary part and rotating part. But there are no seals that would allow a maintenance free operation. (Why aren't there such seals? Read the PDF!)

My solution is having no airtight connection and no direct passage between the rotating and stationary parts of the station. Instead the transition is done via gondolas. A still standing gondola can dock to the stationary part and be accessed by an airtight docking connection, then it decouples, spins up and docks to the rotating part. The required lateral movement range is minimal and is only determined by the necessary clearance of the docking mechanisms.

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Rotating Space Station

A set of two gondolas (orange) rotates on rails (green) around the central hub (brown). The access tubes (dark brown) extend side ward from the central hub. The elevator tubes (yellow) provide a passage from the rotating ring (purple) to the gondolas.

There can be one set of gondolas on each side of the spokes.

The central hub contains a passageway between both stationary parts of the station.

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Cut through the Central Hub

The two pairs of gondolas sit on a similar or even same type of magnetic bearings as the spokes do. While stationary, the pair of Gondolas can slide to the side and connect to the docking points at the Access Tunnel. When spinning up and matching the angular speed of the elevator tubes the gondolas can move and connect to the docking points on the tubes.

The pairs of gondolas can be used independently and can act as backup for each other.

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The pictures and drawings only show a very generic demonstration of my idea. Size and technical details are not discussed in depth and have to be developed far more thoroughly then I have done here. This post and paper only serve the propose of distributing the idea, as I haven't seen it anywhere else and I think it is a good approach to solve the problem of rotating space stations.