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I'm curious, if a space station were rotating to produce a gravity-like force, would being able to see large portions of the sky disorient human beings? Is there any research on the maximum rotation of the "sky" before human beings become disoriented, if at all?

The picture below sparked this curiousity, although I don't think it actually has windows to see into space.

I've made a few calculations with SpinCalc. A 200 meter radius ship needs to spin at 2.11 RPM. A 1km radius ship rotates 0.9456 times per minute. This is VERY fast compared to the earth's rotation speed of .000694... rotations per minute. That's over 1300 times faster. Unknown artist

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  • $\begingroup$ I think it would depend on how close large objects are in relation to the rotating station. If it's very close by then the spinning could be disorienting as any outside objects (plants, moons, etc) would appear to be spinning. If it were out in the middle of space then perhaps the spinning would be significantly less noticeable and therefore less disorienting. $\endgroup$ – ElScorcho Feb 1 '15 at 2:09
  • $\begingroup$ @ElScorcho The backdrop of the stars is ever present. I'm not so sure a large nearby object would help or hinder $\endgroup$ – Premier Bromanov Feb 1 '15 at 2:12
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    $\begingroup$ Almost no one looks at the sky anyway. Clouds fly by without making people dizzy. $\endgroup$ – LocalFluff Feb 1 '15 at 2:29
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    $\begingroup$ @LocalFluff Right, but in order to produce 1g of force, the station has to spin pretty quickly. About 2 RPM for a 200 m radius ship. As you get larger, you spin slower, but by today's standards, a large ship of about 100 - 300 meters across, you're still looking at 1-2 RPM. This is a huge difference from clouds passing overhead in 5-10 minutes (which also disappate and grow and are not constant shapes). Imagine the constant backdrop of the stars rotating 360 degrees every 30 seconds. Even a 3km ship is 1 rotation per 2 minutes. $\endgroup$ – Premier Bromanov Feb 2 '15 at 18:58
  • $\begingroup$ Maybe getting dizzy by looking out of the window from a spinning spaceship is good? Don't need to smoke any funny grass, which saves some oxygen too. Sorry, but I'm not the only one speculating wildly here. $\endgroup$ – LocalFluff Feb 2 '15 at 19:18
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This study, by Soeda, DiZio & Lackner (2002), found that - without including the visual effects of gazing out a spacecraft's window - Coriolis forces rising from rotation caused subjects to soon lose some control while doing certain tasks, including just standing and moving about.

The results of one of their tests found that

The experimenter counted the number of times the subject had to use the railings in order to avoid losing balance. Each contact involved a momentary push against the rail with the back of the hand. Subjects had to use the rails more frequently during rotation than pre- or post-rotation, and more frequently when their eyes were closed than open. Pre-rotation there were 0.25 touches per trial in the dark and none with vision; per-rotation there were 5.04 touches per trial in the dark and 1.16 when the subject’s eyes were open; post-rotation there were 0.125 touches per trial in both visual conditions.

In all the tests, closing eyes did not help subjects retain control; in fact, it lessened their ability to control themselves. However, the latter two of the authors had found (in previous experiments) that adaptation was possible:

However, when permitted to make repeated movements, subjects quickly become more accurate and are able to perform near normally within 10–15 reaches (Lackner and DiZio 1994). Such adaptation means that the subjects’ nervous systems have planned anticipatory muscle innervations which cancel the consequences of the Coriolis forces. Aftereffects are present post-rotation with movement paths being mirror image to the initial ones during rotation.

A NASA page on the researchers' other work noted that

DiZio and Lackner have found that people can adapt to rotational speeds as fast as a carnival-ride-like 25 rpm. That's about as fast as people turn their bodies during day-to-day life.

This would seem to be a decent estimate of an upper limit if only Coriolis forces are taken into account.

In this study (and related ones), it seems like simply the rotation - not the visual perception - is the cause of problems. That said, microgravity environments on their own can cause problems (see Oman et al.). This also states

Windows continue to be a matter of disagreement. In addition to concerns about structural integrity, environmental control (including radiation shielding), and cost, rotation introduces the issue of dizziness. Payne [20] and others have suggested that, "to avoid disorientation," windows should not be provided in rotating environments. But depriving the inhabitants of an outside view would do nothing to alleviate the vestibular effects of rotation. On the contrary, it may promote the mismatch between visual and vestibular perception that leads to motion sickness [15]. Windows might provide an obvious, natural aid to orientation, in addition to the abstract, formalist cues discussed previously.

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  • $\begingroup$ Really great answer :) $\endgroup$ – kim holder Oct 2 '15 at 0:30
  • $\begingroup$ @kimholder Thanks. I wish I had been able to get more information on visual studies, though. . . $\endgroup$ – HDE 226868 Oct 2 '15 at 0:31
  • $\begingroup$ Seems like you sort of did to me lol $\endgroup$ – Premier Bromanov Oct 2 '15 at 15:40
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    $\begingroup$ I would expect the hardest for people to adapt is that walking in the opposite direction of rotation will make them experience less acceleration and therefore feel less heavy. $\endgroup$ – ChrisR Oct 2 '15 at 19:14
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Your inner ears will complain, not your eyes, if you rotate at more than ~1 rpm. The Stanford Torus study, which was the source of your picture, was just under 1000 m as a radius.

Sunlight was bounced off of a large mirror, a small ring mirror, and several other surfaces to get high energy particles absorbed before shining on the crops and habitated area.

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    $\begingroup$ Add a link or two to references , and expand this with anything establishing whether people can be disoriented by seeing movement, and this is an answer. Lacking something that directly addresses the visual aspect, it really isn't $\endgroup$ – kim holder Aug 30 '15 at 2:43

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