# Quick question on ringed artifical gravity.

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#### Valcan

##### Guest
Hey guys i just have a quick question wondered if ya'll could help me.

To provide artifical gravity to a station or ship in space one idea is to have a ring that rotates. Now i was wondering could this work or would there need to be Two circular habs rotating in different directions to cancel any inertial affects caused upon the rest of a station.

And what i mean is imagine a long tube. There is a ring hab rotating around the tube. Now would there need to be two or would one be fine?

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#### SJQ

##### Guest
Two counter-rotating rings would tend to cancel torque effects; symmetric effects would cancel best. The outward acceleration (= "gravity") caused by the ring rotation doesn't care about the direction of rotation, but there may be secondary effects caused by differing coriolis forces between the rotating rings.

I'm not sure that there is any real advantage to having counter-rotating rings, however. Mass balance issues would not be trivial; one ring is dynamic enough - just one person moving around the ring perimeter will move the center of mass around, and cause precession of the axis of rotation. The axial precession would introduce mechanical stresses that the other ring would have to have the structural integrity to resist, and vice versa. Strength = mass, mass that you have to get into orbit....

I suppose you could have active balancing, but this is not a trivial undertaking. A unidrectional rotation would precess the axis of rotation more (i.e., no cancellation at all), but unless you are pointing antennas, using mirrors for reflected lighting, etc., a slow precession wouldn't hurt, so you could allow it to happen, and not have to orbit the necessary structural strength (= mass) to resist it.

Besides, if everything rotates in the same direction, you can eliminate seals on joints - there aren't any joints to seal, which really reduces leakage issues caused by precessional strains.....

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#### vulture4

##### Guest
First, there is little real need for artificial gravity. People have tolerated over a year in weightlessness without and significant problems. If it's really needed, there is no need for a complete wheel; just connecting two vehicles with a long rope and rotating them about each other is enough. Third, if the vehicle is rotating it has a lot of angular momentum and changing direction would be very difficult, regardless of whether there are counterrotating sections. Probably the simplest approach for a Mars trip is to spin up after entering the transfer trajectory and stop the rotation before reaching the destination.

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#### Valcan

##### Guest
vulture4":14t7wv2i said:
This wasnt for a mars trip accually just wondered if a second ring would be needed to counter act any effects the first transfered to the trunk structure. Also much of the idea was for something like a station in GEO eventually or deep bound craft.

If people ever want to LIVE in space for long time some form of artificial gravity is nessesary.

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#### orionrider

##### Guest
Did you think of a ring rotating around a stationary center, like a wheel around an axle?
Many designs have the center and the wheel as one structure, the whole thing turning:

I like the part where the shuttles have to match the rotation to enter.

Another solution is just a ring, no center. Like a giant donut. No Coriolis effects, no nausea, the whole station 'sees' the same G. :idea:

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#### guile

##### Guest
There is research being conducted to suggest moving away from the large ringed structures to a smaller man sized workout chamber. http://mvl.mit.edu/ag/ Moving away from hours of daily exercise allowing for more actual work to be done in space is a plus! I actually am thrilled whenever this subject is brought up. The need is clear for future long term space occupation.

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#### Valcan

##### Guest
guile":ktjqtfb5 said:
There is research being conducted to suggest moving away from the large ringed structures to a smaller man sized workout chamber. http://mvl.mit.edu/ag/ Moving away from hours of daily exercise allowing for more actual work to be done in space is a plus! I actually am thrilled whenever this subject is brought up. The need is clear for future long term space occupation.
Hehe dont think ya'll are getting my Living in space. I mean From birth to death. I mean basically oneday city states in space. I figure gravity is kinda nessesary for the stable development of a fetus or a human one anyways and that way you wouldn't have to worry about all the affects of weightless enviroments.

Think of it like one section for the people to live and such and another weightless section for docking/construction zero g labs etc.

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#### neilsox

##### Guest
Re: Quick question on ringed artificial gravity.

Space lab had a squirrel (hamster) cage for humans that could produce variable gravity for one or possibly two persons at a time. I presume it worked, but has not been repeated as it likely made the users dizzy from the coriolis effect. A spinning ring does not give the rest of the craft significant gravity, thus it is much less useful than the "rope" tieing two space craft together. The rope is usually called a tether, and some technical advances are needed to insure that the rope is very unlikely to break. Neil

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#### Skyskimmer

##### Guest
vulture4":349d4tzd said:
First, there is little real need for artificial gravity. People have tolerated over a year in weightlessness without and significant problems. If it's really needed, there is no need for a complete wheel; just connecting two vehicles with a long rope and rotating them about each other is enough. Third, if the vehicle is rotating it has a lot of angular momentum and changing direction would be very difficult, regardless of whether there are counterrotating sections. Probably the simplest approach for a Mars trip is to spin up after entering the transfer trajectory and stop the rotation before reaching the destination.
At the most ideal cost of getting launched to space being about 1 mil per head, it makes sense to keep people up their for 5-10 years spans. If your sending multiple people up the training costs alone will add a great deal to the overall price.
Assuming it costs 150 k to train a person on earht for one year, and you have to train 5 people versus 1, your accepting an extra 600 k in costs. That's ignoring the added launch costs, etc.

Again this entirely depends on the price of food/water per year in space, and the additional cost of radiation sheilding for 5 years of exposure versus 1.

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#### eburacum45

##### Guest
orionrider":1izjx74j said:
Another solution is just a ring, no center. Like a giant donut. No Coriolis effects, no nausea, the whole station 'sees' the same G.
Coriolis effects are caused by the rotation itself, not by different parts of the structure rotating at different speeds. If the habitat is large enough to rotate slowly, the Coriolis effects will be minimal - but they will always be there.

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#### orionrider

##### Guest
Sure, but in such a ring the effect is minimal if you don't move quickly in a radial direction (what would be 'up' or 'down' for the inhabitants). Trampoline jumping would probably be dangerous, but otherwise you wouldn't even notice you're not on terra firma.

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#### bdewoody

##### Guest
orionrider":b0tkj6co said:
Did you think of a ring rotating around a stationary center, like a wheel around an axle?
Many designs have the center and the wheel as one structure, the whole thing turning:

I like the part where the shuttles have to match the rotation to enter.

Another solution is just a ring, no center. Like a giant donut. No Coriolis effects, no nausea, the whole station 'sees' the same G. :idea:
Your image didn't come through on my computer but I imagine you posted a picture of the space station from "2001 a Space Odessy". I think a long term heavily populated space station should be constructed along those lines where the hub serves as a space dock. The poster claiming little adverse health effects from micro gravity seems to fly in the face of reports I have seen. I don't think one G would be necessary as probably as low as .5 G would suffice.

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#### Skyskimmer

##### Guest
I don't get it can't you just modify the inner ear in some way to allow for higher rotation. It seems that with some research this could become a non issue. I read in a neurology book that people with inner ear disorders can be trained to balance based on visuals, not motion given the proper cognitive therapys.

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#### neilsox

##### Guest
I suppose the inner ear balance function can be disabled, but the change may be permanent, and it likely would not solve all the problems that strong Coriolis causes. Neil

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#### orionrider

##### Guest
Skyskimmer":bmyox2og said:
I don't get it can't you just modify the inner ear in some way to allow for higher rotation. It seems that with some research this could become a non issue. I read in a neurology book that people with inner ear disorders can be trained to balance based on visuals, not motion given the proper cognitive therapys.
Oh, but something similar happens all the time, no need for surgery or anything fancy. Most sailors working belowdecks adapt quickly. It takes only a few meals overboard for the brain to accept incoherent movements as part of it's environment.
Same for astronauts and pilots. Most experience motion sickness for a while and I can't recall a single one having to be brought back because he didn't adapt.

Coriolis effects can be expected and countered, just like you automatically feel and counter lateral G's when standing in a bus. It takes very little learning.

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