How does a spinning station work in reality?

[WestAir]

Quick question. I Googled it but as amazing as Google is, I couldn't find any pertinent links.

My question is: Say you build a space station that has a Stanford Torus or spinning wheel. Obviously there's no way you can dock space-craft with the part that spins, so the station will need a central hull equipped with the airlocks and docking mechanisms that is "still" relative to the Earth. That said, how does crew transfer from the "spinning" part to the "non-spinning" part? For exceptionally large stations, like ones in Sci Fi, stopping the wheels from spinning isn't reasonable.

So out of pure curiosity, how do you transfer crew and resources between the spinning wheel and the non-spinning central hull of a spinning space station? A ladder that reaches a chamber you have to "jump" through without hitting a support beam?

[Tex]

As to spinning space stations, I've never seen any that only have part of the station rotating, usually it's the entire station that does it. Not sure... I honestly think that the easiest way to do it would be, ironically, to stop the station's rotation.

Of course, due to such a problem, that's why these stations are limited to Sci-fi. Real-life spinning crafts would use a tether and fuel from the manned portion to create a rotation between it and an unmanned counterweight. This is only useful during long duration mission, such as those to Mars, because of the energy required to get a spin significant enough to create artificial gravity.

[Tinyboss]

As to spinning space stations, I've never seen any that only have part of the station rotating, usually it's the entire station that does it.

You put the docking port on the spin axis, then spin the incoming ship at the same rate, as seen in 2001: A Space Odyssey.

[lajoswinkler]

Watch "2001: A Space Odyssey" and you will learn.

tinyboss, you were faster

[Kryten]

If the counter-rotating docking port design is used, crew transfer could be by a sort of 'airlock' chamber in the hub-simply a small room that switches from rotating to non-rotating and vice-versa.

[xcorps]

Stanford Torus

Correct me if I'm wrong, but it's revolution speed was supposed to be like 1 RPM and a diameter of a kilometer and a half, so that's only 150 78 m/s of linear velocity. Not exactly challenging to dock with.

Edited May 13, 2014 by xcorps

[jwenting]

yes, you have a rotating outer ring, and a stationary core. After a ship docks, the core is spun up to match velocities with the ring, and lined up with it so the airlocks connect (docked with it, effectively).

At least that's the most common idea, and probably the most workable.

No, you're not having 78m/s linear, you're going to have to match the rotation as well to dock at the outer ring.

[xcorps]

No, you're not having 78m/s linear, you're going to have to match the rotation as well to dock at the outer ring.

That's the linear speed at the outer ring unless someone went and changed physicks... At the core assuming a 200m radius it's 20m/s but either way it's 6 degrees a second of angular rotation. Either way it's a trivial maneuver.

[Seret]

In reality nobody's ever built one, which is why Google wasn't throwing up a lot of links for you. Still sci-fi at this point unfortunately.

The ISS was planned to have a spinning module at one stage. Despite being fairly small rotation rates were quite low, so transition would have been pretty straightforward. Just stop at the entrance and grab a piece the rotating section. If you're at the center you won't really feel any forces until you move towards the outside. On a larger ring this would feel like climbing down into increasing gravity. The bigger the ring the slower it could spin, so transition becomes even easier (although a longer climb down!).

Edited May 13, 2014 by Seret

[nothke]

I can't google it out right now, but I remember reading that a Soyuz docked to one of uncooperative Salyut stations while it was spinning (around it's docking axis of course). So it has actually happened in RL =)

[Nibb31]

There are no spinning stations in reality. I don't see what the problem is to dock with a rotating station as long as you approach it on the axis and your roll matches to the roll of the station. For an observer on the spacecraft, the station would be stationary.

However, I really don't see what the point of a large rotating station in LEO would be. The reason for building a facility in space would likely be to take advantage of microgravity, so you would design it specifically NOT to have gravity. Microgravity is what makes LEO appealing in the first place. If you want gravity, then there are plenty of places only a few hundred kilometers below where you have it.

The only place you *might* need artificial gravity is on long duration interplanetary manned missions. However, even then it might not be a hard requirement because exercice and medication might be able to allow us to live indefinitely without gravity, and that is much easier than building large rotating space cruisers.

[Awaras]

Obviously there's no way you can dock space-craft with the part that spins, so the station will need a central hull equipped with the airlocks and docking mechanisms that is "still" relative to the Earth.

[Seret]

However, I really don't see what the point of a large rotating station in LEO would be.

As a test bed for technologies and knowledge required for long-duration manned trips. Researching that in orbit is a logical stepping stone.

[Nibb31]

As a test bed for technologies and knowledge required for long-duration manned trips. Researching that in orbit is a logical stepping stone.

Yes, but to optimize the science return, your test bed would need a variable rotation rate and radius in order to observe the results with various parameters. As such, a giant ring doesn't make much sense. A "bolo" arrangement with a counterweight and a variable-length cable that you can spin down and spin up would make more sense.

I agree that it makes sense as a science facility, but I don't think we will ever see any 2001-style giant orbital rings.

[WestAir]

If you're going to quote me and correct me, at least quote the part where I said "connected to a central structure that is not rotating." - In this case, a rotating wheel connected to a standard space station. In your video you'd be docking with the nonrotating part of the space station, completely missing the point of me asking how to "transfer crew" between the nonrotating and rotating structures.

EDIT: Also, thanks for linking that video. This game looks utterly amazing. Definitely going to check it out!

Edited May 13, 2014 by WestAir

[Awaras]

If you're going to quote me and correct me, at least quote the part where I said "connected to a central structure that is not rotating." - In this case, a rotating wheel connected to a standard space station. In your video you'd be docking with the nonrotating part of the space station, completely missing the point of me asking how to "transfer crew" between the nonrotating and rotating structures.

EDIT: Also, thanks for linking that video. This game looks utterly amazing. Definitely going to check it out!

Well, you said that "there's no way you can dock space-craft with the part that spins", and the video shows just that, since the whole station is spinning...

[running]

Or like the original Elite game manual states:

Anyone that can't dock to a space station without a docking computer doesn't belong in space.

(Need to go home to look up the exact quote but that was the general message.)

And now I must go and checkout this revamped version of it.

[K^2]

It's tricky, but entirely possible to build an air tight seal that still allows for mechanical rotation. Usually, these involve oils with very low vapor pressure, similar to these used in vacuum pumps, or even ionic liquids to create the seal. You'll have losses, but even a conventional airlock will have some losses. So long as these are sufficiently low, it's not a problem.

[MrZayas1]

I think that maybe if there was a spinning portion of a station there would be a central column that is magnetically connected to the station, but not rotating to dock space craft, then there would be an airlock around it, that would wait until passengers press a button or something, and match rotational velocity with the station, and allow for transfer of crew in and out of the spinning lab. That's how I would envision it But the fact that it is spinning would make things need a little bit of power, to start the station up and keep it rotating. Things like magnetic friction might also come into effect because of the fact that sometimes magnets slow eachother down. We would have to talk to some scientists about it but sure that eventually we could create such a rotating station.

[SargeRho]

Or you just spin the entire station, and spin the ship you are in as you dock with the station. Much simpler and easier to do.

[MrZayas1]

yes, you have a rotating outer ring, and a stationary core. After a ship docks, the core is spun up to match velocities with the ring, and lined up with it so the airlocks connect (docked with it, effectively).

At least that's the most common idea, and probably the most workable.

No, you're not having 78m/s linear, you're going to have to match the rotation as well to dock at the outer ring.

I think that instead, the core should be stationary, having an arm that begins to rotate with people inside it to match velocities with the rotating section, meet up with the docking ports, and align itself so you can go into the spinning module. If like you said the ship docked onto the core, and it began to spin, the extra mass offsets it's center and it would begin gyrating wildly undoubtedly tearing the station apart

[Seret]

Why are you guys thinking crew might have any trouble moving from a rotating to a non-rotating part of the station? Really can't see it as a problem, it'd be no harder than negotiating a merry-go-round/roundabout at a child's playground. As long as you weren't too drunk it should be fine.

[MrZayas1]

Why are you guys thinking crew might have any trouble moving from a rotating to a non-rotating part of the station? Really can't see it as a problem, it'd be no harder than negotiating a merry-go-round/roundabout at a child's playground. As long as you weren't too drunk it should be fine.

It would most definitely be a problem, because if you are moving from a body that isn't moving in space (not counting orbital movement) to one that is indeed moving, it's like walking in front of train tracks, because it is moving and you are not. Basically what happens is you either end up with a concussion, or a big red splat on the wall if it is moving fast enough.

[Moon Goddess]

Why are you guys thinking crew might have any trouble moving from a rotating to a non-rotating part of the station? Really can't see it as a problem, it'd be no harder than negotiating a merry-go-round/roundabout at a child's playground. As long as you weren't too drunk it should be fine.

It would most definitely be a problem, because if you are moving from a body that isn't moving in space (not counting orbital movement) to one that is indeed moving, it's like walking in front of train tracks, because it is moving and you are not. Basically what happens is you either end up with a concussion, or a big red splat on the wall if it is moving fast enough.

Except it's really not. Yes the space station is traveling 17,100 mph, but so are you, so they cancel out we ignore them. The rotating section is rotating at between 7-8 RPM for mars gravity. For an enterance with a 2 ft radius, that's less than a mile an hour. The train is traveling at 50MPH. It really is like hopping on a spinning merry go round.

[Seret]

It would most definitely be a problem, because if you are moving from a body that isn't moving in space (not counting orbital movement) to one that is indeed moving, it's like walking in front of train tracks, because it is moving and you are not. Basically what happens is you either end up with a concussion, or a big red splat on the wall if it is moving fast enough.

Let's take a worst case scenario: a small (20m) ring spinning for 1g at the rim. In a 2m entry section the difference in speeds would be 1.4ms^-1. That's about waking speed, and in reality you wouldn't have a ring that small spinning that fast.