Admiral Lord Nelson in Space

[Gian]

As a means of creating artificial gravity sci-fi authors and movies have often suggested using a centrifugal force in a rotating space station or spacecraft, as in 2001 A Space Odyssey

However the idea apparrently fails to take note of the "Coriolis effect" which would cause immediate nausea and loss of balance, like motion sickness, unless the rotating radius were very large eg 1 mile+

Yet even Lord Nelson was seasick for several days after putting to sea, but would then gain his sea legs and be unaffected.

Is it possible that the bodies of individuals like the crew of 2001's spacecraft Discovery One may adapt after a few days and get their "space legs" leaving them unaffected by the Coriolis effect?

Thanks

GIAN🙂

Edited November 28, 2022 by Gian
Better grammar

[exchemist]

52 minutes ago, Gian said:

As a means of creating artificial gravity sci-fi authors and movies have often suggested using a centrifugal force in a rotating space station or spacecraft, as in 2001 A Space Odyssey

However the idea apparrently fails to take note of the "Coriolis effect" which would cause immediate nausea and loss of balance, like motion sickness, unless the rotating radius were very large eg 1 mile+

Yet even Lord Nelson was seasick for several days after putting to sea, but would then gain his sea legs and be unaffected.

Is it possible that the bodies of individuals like the crew of 2001's spacecraft Discovery One may adapt after a few days and get their "space legs" leaving them unaffected by the Coriolis effect?

Thanks

GIAN🙂

I'm not sure the Coriolis effect would have that dramatic an impact. In most uses of rotation to produce artificial gravity that I have read about, the spacecraft would take the form of a tubular wheel. According to my understanding , the Coriolis effect would chiefly affect objects moving radially, rather than circumferentially.

Or am I missing something?   

Edited November 28, 2022 by exchemist

[Lorentz Jr]

1 hour ago, Gian said:

the "Coriolis effect" which would cause immediate nausea and loss of balance, like motion sickness, unless the rotating radius were very large eg 1 mile+

Yeah, I would like to see documented evidence of this. Seasickness and airsickness are caused by repeated back-and-forth accelerations, linear and/or rotational, which are in turn caused by interactions with the surrounding water or air. But that wouldn't be an issue on a smoothly rotating space station. Maybe if someone starts jogging around the station, but even then, the person will already be rotating along with the station, and that's a constant of the motion. So, to paraphrase what exchemist said, I think it would only happen if the tube is "tall" enough (radially) for the person to jump "up" (inward, toward the center of the wheel), because then the person would be at an angle when they land on the outer "floor" of the wheel again.

EDIT: There is a force from jogging or otherwise moving around the wheel (2m omega v'), but it would just make the person feel heavier. Dizziness would have to come from the up-and-down motion of jogging, sitting down and standing up, etc., or the acceleration (partially rotational) of speeding up and slowing down.

Edited November 28, 2022 by Lorentz Jr

[MigL]

Centrifugal force is a fictituous force made apparent by motion in a rotating frame of reference.
If you have no access to the external stationary frame, or the motion is slow enough that it is hard to detect, there will be nomotion sickness.
IIOW, if you cannot see outside the rotating tube providing artificial gravity, or the stars are far enough away that motion is hardly noticeable, there is no problem.

[Lorentz Jr]

1 hour ago, MigL said:

access to the external stationary frame

Every object is subject to its own inertia, both linear and rotational. If you jump across to the other side of the space station without changing your rotational motion (assuming there's room to do that), you'll land on your face, because your rotation will only be enough for the angle the station turns through over the duration of the jump, not the longer angle between your starting point and your landing point. So getting up might tend to make you dizzy.

If the station is small enough, the up-and-down motion of jogging might subject you to a noticeable rotational force every time one of your feet lands on the floor. I guess it's a question of whether that would feel unpleasant, or whether you can land and then push off on each foot without too much of a rotational jolt. It might not be so bad, but that's a question of physiology.

A rotating space station is like a merry-go-round. I think Gian has a point, although he may have exaggerated it.

Edited November 28, 2022 by Lorentz Jr

[swansont]

One issue with the Coriolis force is that if you are standing up, you have a radial velocity and the coriolis force will push you in a perpendicular direction. 

But it’s only present if you are moving relative to the station

 

 

[Ken Fabian]

My understanding is this an issue with the human inner ear, the motion/balance detection part. There is a difference and mismatch between the perceptions of motion, where eyes and other senses say one thing - that you are within a motionless space - but the inner ears are detecting rotation and that becomes disorienting and nauseating. Those little stones in those ear canals - the semi-circular canals - will keep giving the sensation of rotation and being unbalanced unless the rotation is slow enough.

Edited November 28, 2022 by Ken Fabian

[Gian]

22 hours ago, Lorentz Jr said:

TO EVERYONE

 

If you have time, can people give me their response to this video on artificial gravity please?

The coriolis effect is discussed from 13.31

I've no science beyond GCSE so I can't evaluate all the technicalities.

GIAN xxx

 

Edited November 29, 2022 by Gian

[exchemist]

2 hours ago, Gian said:

 

If you have time, can people give me their response to this video on artificial gravity please?

The coriolis effect is discussed from 13.31

I've no science beyond GCSE so I can't evaluate all the technicalities.

GIAN xxx

 

Yes, I think the point is that "r dot" signifies velocity in the direction of r, which means radially. That's what I and others have been saying.

What is misleading, it seems to me, is that the film accompanies this by showing a film of someone jogging round the circumference, i.e. not moving radially. I suppose there is a little bit of radial motion, in that the jogger is moving up and down a little as he runs. Whether that is enough to cause a sensation of his head moving sideways to left and the right, as it goes up and down, I am not sure. It will depend on the radius of the circular tube he is running inside. It's a very small diameter tube in the film. Whereas If you think of 2001, for instance, the space station is hundreds of metres across. (The effect of r dot will be much less because ω will be much less: you need a lower rotation rate to simulate 1g of gravity in a larger ring.)   

The two guys trying to throw a ball to one another, across the centre of the circle as they rotate, is a much better example of what happens, I feel. That is radial motion, so that is the scenario in which the Coriolis effect arises. 

 

[Ken Fabian]

I did a quick look to affirm my recollection that it mostly a problem of human senses and the nausea and discomfit from the mismatch between what our sense of balance is saying and what our other senses say. Sounds a lot like the spinning sensation from lying down drunk on alcohol. I expect actually moving around and adapting our motions to such an environment isn't the problem, the problem is people feel ill.

Whilst actual conditions can't be tested there have been attempts to mimic some of the effects using centrifuges and rotating spaces on Earth. A few different conclusions cited at http://www.artificial-gravity.com/Dissertation/2_2.htm - eg -

Quote

In 1960, Carl C. Clark and James D. Hardy, of the Navy's Aviation Medical Acceleration Laboratory (US Naval Air Development Center, Johnsville, Pennsylvania), published "Gravity Problems in Manned Space Stations" in the Proceedings of the Manned Space Stations Symposium [73].  Like Kramer and Byers, they were concerned about "Coriolis acceleration effects", but Clark and Hardy concentrated on the problems of cross-coupled rotations.  Clark subjected himself to 24 hours of 2-g acceleration on a centrifuge rotating at 1 radian/second (9.55 rotations per minute), and noted that "illusions of body and visual field angular motions are generated which are approximately specified in magnitude and direction by the vector product of the angular velocity of the rotating system and the angular velocity of the head."  The threshold for the onset of these illusions was 0.06 radians²/second²; the threshold of nausea was 0.6 radians²/second² [74].  Normal head rotations may occur at up to 5 radians/second.  Therefore, Clark and Hardy concluded, the angular velocity of a rotating space station should not exceed 0.01 radians/second (that is, 0.06 ÷ 5), or about 0.1 rotations per minute.  This is much less than the 7.5 rotations per minute proposed by Kramer and Byers.  Clark and Hardy proposed to stay completely below the threshold of illusions, although the threshold of nausea was ten times higher.  They acknowledged that this might not be practical: at 0.01 radians/second, a 1-g station would need a radius of 320,000 feet. 

 

@Gian - I did watch some of the vid starting from the point you picked out. Sorry, not going to watch the whole 30+ minute video (a synopsis would be good) but what I did watch made no mention of the role of the sense of balance (vestibular/inner ear), only more direct sensations of changing directions and strengths of pseudo gravity. Did I miss it or is it absent? It would be a serious omission - it wasn't hard to find references to the disorientation and nausea as one of, if not the most significant problem for human occupants.

Edited November 29, 2022 by Ken Fabian