Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I Artificial gravity in a rotating space station

  1. Oct 11, 2018 #1
    It is often proposed that gravity could be simulated on a space station by rotating around an axis, such that the astronaut experiences the centripetal force of the space station wall, analogously to gravity. It is usually mentioned that the radius of rotation must be very large to avoid significant Coriolis effect being experienced by the astronaut. My question is this:

    Could Coriolis effects be cancelled by some weird tumbling or precessing program of spin? I imagine this could be accomplished with a constant expenditure of thrust, but what about something inertial, even if it required gyroscopes or whatever?
     
  2. jcsd
  3. Oct 11, 2018 #2

    A.T.

    User Avatar
    Science Advisor

  4. Oct 12, 2018 at 4:20 AM #3

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    Wow, what a strange environment you are suggesting. Actually, the occupants would be far more likely to learn to cope with a very predictable effect like a moderate Coriolis, once they get their sea / space legs. When they return to Earth they are just as likely to fall over without the effect - 'the sways' is a common experience that people get when they return from a few days at sea and stand in their kitchen whilst washing dishes etc..
    And I agree with @A.T. of course!
     
  5. Oct 12, 2018 at 6:25 AM #4

    anorlunda

    Staff: Mentor

  6. Oct 12, 2018 at 1:48 PM #5
    You can study this yourself by riding the Gravitron. Just sit up and move your head around.
    upload_2018-10-12_13-42-4.png

    And Wikipedia: https://en.wikipedia.org/wiki/Gravitron. I know for a fact that Coriolis effects forced me to lay down on the grass for an hour after one ride, while my then 12 year old daughter rode it continuously for hours. Google motion sickness centrifuge for lots of good information.
     
  7. Oct 12, 2018 at 5:42 PM #6

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    I can feel quite nauseous enough after a few rotations of the little roundabout in my granddaughter's local kiddies' playground. I think it's the mucus in my 'tubes'. I definitely no longer have the 'right stuff'. Also, when tacking on my sailboat, Coriolis used to spoil my sense of direction as I tried to change sides in the cockpit and found I was moving diagonally.
     
  8. Oct 13, 2018 at 8:19 AM #7
    My ability to work with vectors is poor I'll admit, but the simple answer seems to be no, right? It is not possible to make Ac zero by changing the angular velocity over time. And would this take into account the possibility of rotation around a separate axis, such as spinning around the radius of the primary rotation? I suppose such an additional rotation would introduce an additional Coriolis acceleration...
     
  9. Oct 13, 2018 at 8:24 AM #8
    The Gravitron is a fixture from my county fair childhood- just the thought experiment of moving around in there makes me queasy. I never had the right stuff. I remember hurling from it, though thankfully not inside the gravitron itself- my lunch came up on the cool down lap on the pirate ship!
     
  10. Oct 13, 2018 at 1:29 PM #9

    A.T.

    User Avatar
    Science Advisor

    You still get one net Ω.
     
  11. Oct 13, 2018 at 4:27 PM #10
    That's the fundamental insight I was missing. I can see why it is the case. Thanks!
     
  12. Oct 16, 2018 at 6:03 PM #11
    The real problem is not the corriolis effect but simply the angular velocity.
    The higher that angular velocity, the bigger the problem astronauts will have when they change the orientation of the head. For example, they may acclimate to running around with the spin of the station. But then sitting down at a desk and facing in a different direction will take some recovery.

    Here is a good article:

    From https://flightsafety.org/hf/hf_jul-aug95.pdf
     
  13. Oct 16, 2018 at 6:11 PM #12

    DaveC426913

    User Avatar
    Gold Member

    :woot:
    I have this image of you diving for the port gun'le and instead finding yourself below, sprawled across the dinette.

    "I think I made a wrong toin at Albaqoickie..."
     
  14. Oct 17, 2018 at 3:28 AM #13

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    Haha. Its could happen if I were not hanging onto the tiller! Fact is, the part of the boat that my brain was aiming at and which my body control was using is not there any more. I reckon that's how we could describe the (fictitious) Coriolis Force. Physics was not uppermost in my mind at such times but I guess a really competent helms person would be doing those sums automatically during all manoeuvres. It's part of getting your sea legs, I suppose.
     
  15. Oct 17, 2018 at 3:34 AM #14

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    True but there is also an unexpected translation. That's related to Coriolis even when you are moving your head to change view of the inside of the cabin. I think that the condition where these effects come is could well be related to differences between what's experienced by each sides of our balance mechanism. I hesitate to use the phrase 'what's really happening' . . . . . but there's an explanation in there somewhere.
     
  16. Oct 18, 2018 at 4:45 AM #15

    A.T.

    User Avatar
    Science Advisor

    And how exactly does angular velocity cause a problem?

    According to the article, human sensory organs detect angular accelerations, not constant angular velocity.
     
  17. Oct 18, 2018 at 7:35 AM #16
    I addressed this in my original post.
    People will soon adapt to a constant angular velocity (in less than a minute according to the article).
    But every time they reposition their head, the clock starts over. So if you walk in a straight line for 1 minute, you're OK. But before you start a turn to the left or right, you may want to close your eyes and keep them closed well after the you have completed the turn.

    But the problem is not just a matter of discomfort. The motion information is used with eye movement - so when you're "dizzy" from turning, everything seems to be moving. Your eyes will not properly track stationary objects - like a control panel or computer terminal.

    For pilots, this falls under the category of vertigo and spacial disorientation - and is often fatal. It may not be fatal for the space station occupant, but there is a technique that can be borrowed from pilots to deal with this. If you shake your head vigorously, you can scramble your inner ear balance mechanism and temporarily shut it down. This will give you back your vision.
     
  18. Oct 18, 2018 at 8:15 AM #17

    anorlunda

    Staff: Mentor

    Wow, thanks for sharing that. I was never taught that in my pilot training. It sounds very sensible.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted