Imagine a diameter 1000km long O'Neill cylinder orbiting a dwarf star, it acquires most of its energy from the star directly.

This space station is designed for research purpose but it has a relatively huge population density for it's size, and the inhabitants are actually part of the experiment to see how human copes in low g and experiencing irregular day and night cycle.

Rather than using smart panels to filter lights from the star the station adopts a rather interesting approach to simulate day and night similar to condition on Earth, the entire station will flip over at regular time interval by itself unpowered thus saving precious energy.

This is made possible due to the tennis racket effect so I am curious would this kind of oscillation match our circadian rhythm without wasting resources or it could put the whole experiment and all it's subjects in jeopardy? enter image description here

As you can see this space station has a striking resemblance to an ill designed two handles tennis racket, it is consisted of 3 main components: Solar panel arrays(net), Living space(rim) and the Machinery(grip). The Machinery can move along the Living space by wheels to control the period of oscillation when tennis racket effect happens.

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    $\begingroup$ I reckon that the job in which the majority of the population will work is cleaning up the vomit from the walls of the city. At the size of a o"Neill cylinder, imagine the accelerations required to finish a flip in 1 hour, followed by another 11hours when they'll need to flop back. See also $\endgroup$ Dec 1, 2021 at 3:16

1 Answer 1


Very likely, no, you won't get any energy savings, on the contrary. Additionally you'll make the life of the inhabitants miserable and the structure unsafe on long term.

During the transition, the accelerations will be quite high - 1 hour transition from night and day (and back) every 11 hours.

Additionally, those accelerations will be have a component oriented orthogonal with the centripetal direction. Letting aside people thrown all over the place into the walls (or the ceiling) of the buildings, this will imply a serious effort invested in the structure of the hull and of the buildings inside the space station, very likely seriously increasing the mass of the station.
Rationale: without the crazy tennis racket behaviour, the hull material must resist tensile stress and the buildings inside must resist compressive stress. With it, both structures will need to answer to bending and shearing stresses too. Put on top of it even the mundane sewage pipes (and their backflow risks) and the cost of anchoring them.

The two main concerns going against it:

  • With a serious mass increase, I doubt that there will be any overall energy saving after considering the energetic cost to control the flip-flop transitions

  • If you add considerations related to materials fatigue due to exposure to structural stress (instead of being under almost constant load), the long term maintenance costs are going to eat any meager saving one can obtain by simple pulling on/off some trivial shades.

(and I didn't even touch what the effect would be against non-structural materials, like the soil in the agricultural sector or the water in the ponds of the recreational areas. Just stop sloshing everyone inside, will you?).


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