Nausea from habitation cans spinning too fast?

[MC.STEEL]

I am researching stuff for my hard-ish sci-fi im working on and the fact that a small can should spin faster compared to a wider can to achieve the same force.But it should not spin more than 3 rpm because the crew will start to feel nauseous.And this a bit strange for me.As far as i know motion sickness occurs from your inner ear sensing that you are moving but your eyes sense nothing is moving,or vice versa.Why would it cause nausea?

[Accelerando]

you would feel less effect of centrifugal force in your head than in your feet. atomic rockets links to a study on how this might not cause nausea if the small hab is spun up in increments.

[ThirdHorseman]

We had a lively discussion about some of this in this thread about space habitats:

http://forum.kerbalspaceprogram.com/threads/47602-Space-Habitats

Unfortunately that study from the Atomic Rockets link is behind a paywall. Here are some good reads on why spinning habitats can cause issues:

http://www.spacefuture.com/archive/artificial_gravity_and_the_architecture_of_orbital_habitats.shtml

http://chapters.marssociety.org/usa/oh/aero2.htm

Basically, there is a relationship between the speed of the spin and the diameter of the habitat. So just saying "3 RPM" isn't enough, it depends on the design.

[MC.STEEL]

We had a lively discussion about some of this in this thread about space habitats:

http://forum.kerbalspaceprogram.com/threads/47602-Space-Habitats

Unfortunately that study from the Atomic Rockets link is behind a paywall. Here are some good reads on why spinning habitats can cause issues:

http://www.spacefuture.com/archive/artificial_gravity_and_the_architecture_of_orbital_habitats.shtml

http://chapters.marssociety.org/usa/oh/aero2.htm

Basically, there is a relationship between the speed of the spin and the diameter of the habitat. So just saying "3 RPM" isn't enough, it depends on the design.

You mean that a 5m radius hab is going to create 0.05 of a g while a 100 meter one will make about 1 g under 3 rpm(online calculators for the win).I get that.

But thanks anyway.

[K^2]

The cause of nausea is Coriolis Effect. If you move your head in a spinning habitat, it results in forces on fluids in your inner ear, which end up sensing a different direction for "gravity" then what you perceive from your eyes and your feet^*. From perspective of your brain, it is the same problem as caused by too much alcohol, for example, when inner ear also sends wrong information, and is interpreted as poisoning. Hence the nausea to try and get rid of whatever it is that got you poisoned.

^* There are 3 senses that help you determine orientation in space, not just two. Pressure on the soles of your feet is just as important as sight and inner ear. Usually, if just one of the three is off, but the other two agree, the two senses in agreement can override the one that isn't. Placing your feet firmly on the ground can often help get rid of the nausea induced by problems with inner ear.

[Nuke]

SpinCalc is your friend.

[Idobox]

There would also be significant pseudo-tidal effects, the artificial gravity changing quickly with radius.