Tethered Space Station - Artificial Gravity

[Allan]

hello again. I'm back and I need a little understanding in a matter. You guys were extrodinarily helpful with my last conundrum and I'm hoping you can help with this one as well.

Premise: A space station tethered to the Earth with a thick king post structure between two rotating rings (3-5 RPM).

Which centrifugal force (artificial gravity) would win out if people were to inhabit the king post structure? The rings?

On these rings if a shuttle were to be released into space would it be flung into space because of the roattion speed around the Earth or would it merely drift away governed only by the 3-5 RPM of the rings? Would a departure from the station be more feasable from the king post itself? Would either scenario be safe for people (strapped in of course).

I know these is a wildly impractical questions but I'm a writer, not a physicist or mathmatician. Any help to better my understanding is appreciated.

 

[HAL9001]

Now, I don't like centrifugel force.
If it rotates rightwards and you go leftward in it there is no grvity anymore.
If you go in the same direction, it rotates, there is some stronger gravity.
:facepalm:
Better would be a sopecial "back and forward" moving with just short times with lower gravity.

 

[River Crab]

I'm not sure I completely understand, but it just sounds like a space elevator with 2 centrifuges on it.
So the entire elevator would be in orbit, which makes sense if you think about it. So the gravity inside the "King Post" would be the same as in a vessel orbiting at that altitude, and if you released anything from it, it would just act as if you released it from an orbiting vessel.

EDIT: Wow, what was I thinking. Ignore everything above.

So please do some research on [ame="http://en.wikipedia.org/wiki/Space_elevator"]space elevators[/ame] if you want anything more about that.

 

[Usquanigo]

Now, I don't like centrifugel force.
If it rotates rightwards and you go leftward in it there is no grvity anymore.
If you go in the same direction, it rotates, there is some stronger gravity.
:facepalm:
Better would be a sopecial "back and forward" moving with just short times with lower gravity.

On a ring large enough for the people on board to not feel like they were in a centrifuge, the speed you would need to move to feel any real effect on the percieved 'gravity' would be pretty serious indeed. Perhaps if you were to put a giant running track and got somebody who was a trained runner, you might manage it. But with rooms and obstacles, and just moving around - no, you won't feel any difference at all, regardless of which direction you move or how long you do it.

A pendulum like you suggest has all kinds of problems associated with it. Firstly, the forces from making it change direction are quite high and will add lots of extra wear and tear on the components and require either a MUCH more massive vehicle to have it mounted to, or much more fuel to stop the torque from adverselt affecting the ship.

More importantly, your crew would get slammed against 1 wall as it starts to accelerate, then into the other wall as it slows down. They will also experience constant fluctuations in their apparent gravity. It would probably cause sea-sickness, make people miserable, break lots of things, make many experiments impossible, and just all around be a really bad idea.

 

[Allan]

I'm not sure I completely understand, but it just sounds like a space elevator with 2 centrifuges on it.
So the entire elevator would be in orbit, which makes sense if you think about it. So the gravity inside the "King Post" would be the same as in a vessel orbiting at that altitude, and if you released anything from it, it would just act as if you released it from an orbiting vessel.

So please do some research on [ame="http://en.wikipedia.org/wiki/Space_elevator"]space elevators[/ame] if you want anything more about that.[/QUOTE

Actually orbiting station would be the GEOSYNC portion of a space elevator (not the counter weight). The kingpost (for lack of a better word) would be the receiving bay of the elevator (assumed to be subject to centrifugal force from the tether). The Rings themselves would be (in my view) the place were people would reside.

In the king post I envision centrifual force placing people with their heads facing earth and their feet away from Earth (or weightless in freefall?). In the rings at 3-5 RPM I would think the Earth would reside sideways toward a person with people walking like a hamster on a huge (perhaps 10 miles in circumference) constantly moving wheel.

Provided my estimates are right (and they may not be) I would hope that releasing a shuttle from the rings would just allow it to drift off and releasing a shuttle from the king post would fling it (provided there is centrifugal force 40K or so miles from earth)?

 

[River Crab]

Ok what was I thinking. No, you wouldn't be in orbit until you got to GEO point on the tether. But you would still be in freefall, I think.
Anyway, do you mean the rings are at the GEO point on the tether, and the "King Post" extends past GEO? Anything past GEO on the tether would fly away when released and anything below it would fall. Unless I'm wrong again.

 

[Usquanigo]

I'm not sure I completely understand, but it just sounds like a space elevator with 2 centrifuges on it.
So the entire elevator would be in orbit, which makes sense if you think about it. So the gravity inside the "King Post" would be the same as in a vessel orbiting at that altitude, and if you released anything from it, it would just act as if you released it from an orbiting vessel.

So please do some research on space elevators if you want anything more about that.

Actually orbiting station would be the GEOSYNC portion of a space elevator (not the counter weight). The kingpost (for lack of a better word) would be the receiving bay of the elevator (assumed to be subject to centrifugal force from the tether). The Rings themselves would be (in my view) the place were people would reside.

In the king post I envision centrifual force placing people with their heads facing earth and their feet away from Earth (or weightless in freefall?). In the rings at 3-5 RPM I would think the Earth would reside sideways toward a person with people walking like a hamster on a huge (perhaps 10 miles in circumference) constantly moving wheel.

Provided my estimates are right (and they may not be) I would hope that releasing a shuttle from the rings would just allow it to drift off and releasing a shuttle from the king post would fling it (provided there is centrifugal force 40K or so miles from earth)?

Consider the ISS or the Space Shuttle when it's in orbit and you see the video footage of the weightless/microgravity.

Now consider the speed vs altitude aspects of orbital mechanics.

Every altitude has a speed which corresponds with it. Travelling that speed at that altitude means you maintain a circular orbit and feel no gravity because everything is counter-balanced.

This means that in your elevator shaft, until you reach GEO, you would fall back down to Earth should your elevator platform go away. That means you would be standing on your feet, head away from the planet.

Once you reach GEO, this is zeroed out, and you would feel no gravity at all. If you were step outside, you would not see the elevator leave you behind, nor would you fall toward the planet, nor fling off into space away from the planet.

This would be the same as going faster, lower down.

 

[T.Neo]

Sounds like a pretty large and impractical structure.

There was quite a good thread a while back on the topic of space elevators and gravity.

 

[Allan]

Sounds like a pretty large and impractical structure.

There was quite a good thread a while back on the topic of space elevators and gravity.

Well it is unfinshed, still being revised, speculative fiction. Besides I origionally said it may be wildly impractical. :tiphat:

 

[tori]

(...) But with rooms and obstacles, and just moving around - no, you won't feel any difference at all

True, but a ring station with that kind of a diameter would very likely have some kind of a tram or other high speed commute system, so the concern remains.

 

[Allan]

True, but a ring station with that kind of a diameter would very likely have some kind of a tram or other high speed commute system, so the concern remains.

Actually I envisioned moving walkways like you'd see in an airport to move from place to place horizontally and elevators to move vertically between levels. I'm thinking if the people never have to leave the floor they should maintain the speed and the artificial gravity of whatever portion of the station they are in.

I would think the king post to be weightless at its center and centrifugal force taking over the further away from Earth you go.

The rings would be traversed using a tram to aid in the adjustment from no gravity to away from the king post.

I'm thinking the less independant movement individuals do the less complication and likihood for trauma for them.

 

[HAL9001]

I think I dom't really understand.

Do you mean somthing like that?:

 

[T.Neo]

I assume the OP is talking about something like this:

Such an object spinning at the same rate as the Earth would provide centripetal acceleration of only 0.0192 G.

 

[HAL9001]

Ohhhhh.

What a genius idea. I had it months before, I tought it would be too crazy but it's so cool.

:woohoo:
:jj::jj::jj:

 

[T.Neo]

Yes, a ring around a planet. That provides only 0.0192 G.

I don't see it as a viable habitat, though it might be a useful structure for space-based industry.

 

[HAL9001]

well, it won't ruin the landcape, but the night-sky-scape
:lol:

Well, what would be if there is a tethered inner Ring and an outer ring, rotating fatser than the inner to make artficial gravity at 1G?
Thatn would make the average rotation at every place so, that you have every place near an orbit, so that the whole construction don't has to be so robust.
Well I quote myself, now:

;196015]Now, I don't like centrifugel force.
If it rotates rightwards and you go leftward in it there is no grvity anymore.
If you go in the same direction, it rotates, there is some stronger gravity.
:facepalm:
Better would be a special "back and forward" moving with just short times with lower gravity.

What would be, if there are lot's of those gravity-rooms inside?

 

[Usquanigo]

Actually I envisioned moving walkways like you'd see in an airport to move from place to place horizontally and elevators to move vertically between levels. I'm thinking if the people never have to leave the floor they should maintain the speed and the artificial gravity of whatever portion of the station they are in.

I doubt there would be a moving walkway or tram system. The habitats would simply not be THAT big to need them. And if you REALLY had to get to the opposite side that fast, go "up" through one of the spokes, through the hub abd back "down" again.

Either way, this sort of thing would be living quarters and science lab (and sick bay), generally not any potentially emergency place like the bridge or engineering.

I would think the king post to be weightless at its center and centrifugal force taking over the further away from Earth you go.

As has been discussed already, until you reach GEO, you would be feeling Earth's gravitational pull. This is because you're in a tube that is anchored to a GEO satellite/station. That anchor is held in place because it is going the right speed to maintain orbit. Slower than that, and it would fall. In closer than that - at the same speed - and it would fall. And that latter case is what you'd have in the tube on the entire trip up.

Now, if you extended the tube out past that point, you would start to feel some artificial gravity in the direction opposite the planet. But you would have to get VERY far out to get a full G. You would be better to use rings of reasonable diameter much closer in in an orbit of their own.

 

[HAL9001]

If there is used my outer ring princip, you can trvel by going into the outer ring (with a special system, because it moves so fast), wich would move with ca. 14 km/s and go at the other side of the earth in ca. 25 minutes.

 

[T.Neo]

Also something to note is that the maximum radius of a habitat rotating to produce 1 G is around 1000 km with carbon nanotubes. To go bigger, you either need unobtanium, or some sort of active stabilisation (though I fail to see how it would work with a structure in tension).

 

[HAL9001]

or an rotating ring like the outer ring of my concept.

don't forget, at that construction every place of the ring is near an orbit.

so or so, I think at a station with an radius of 750 km and so it ould go.
or use some of this modern materials wich will be invented in a few years...
they are working hard at materials at the moment




but, at the way...
why isn't there an easy space elevator for orbiter?