How does station alignment and rotation work??

[specialsymbol]

Ok, this seriously troubled me since when I saw it for the first time:

The stations are often(*) aligned in a way that points the slot in the general direction of the planet they're orbiting.
But they're rotating!

So how can this be?
That would mean that the station is, on the opposite side of the orbit, pointing exactly away from the planet, due to the conservation of momentum. Yet I've never seen that, and I've observed stations throughout their complete orbit.

So how does station orientation work? Is there any reasoning behind it? Are they cheating?



(*) often means, their orientation is somewhat arbitrary - some stations point (sometimes?) almost exactly at the planet, some stations almost perpendicular to that direction. It's never clear why they're pointing in which direction. And I also can't reliably drop out of SC in a specific orientation to them. General orientation, yes - as I said, they always point in the somewhat general direction of the planet. So even if they're oriented perpendicular to that axis and you approach from the planet, you never are off more than 90°. On the other hand, if you approach from above or below you can arrive exactly at the wrong side. You could also then hit it spot on, but somehow that's less likely to happen..

 

[Hawkmoon]

Ok, this seriously troubled me since when I saw it for the first time:

The stations are often(*) aligned in a way that points the slot in the general direction of the planet they're orbiting.
But they're rotating!

So how can this be?
That would mean that the station is, on the opposite side of the orbit, pointing exactly away from the planet, due to the conservation of momentum. Yet I've never seen that, and I've observed stations throughout their complete orbit.

So how does station orientation work? Is there any reasoning behind it? Are they cheating?



(*) often means, their orientation is somewhat arbitrary - some stations point (sometimes?) almost exactly at the planet, some stations almost perpendicular to that direction. It's never clear why they're pointing in which direction.

So you not even considering the possibility that a station has some form of thruster to keep then in position, also if you spin the station at one revolution/orbit of the planet then the same side will stay pointing at the planet as you say "due to the conservation of motion" . There are plenty of satellites in orbit around the earth that keep the same side pointing towards the planet. The variation in the aliment is most likely down to a lot of stations having an elliptical orbit.

 

[Derpster Frey]

The station is not spinning towards the planet they are orbiting.
They are spinning on the axis of the planet.

I am no scientist and English is my third language, so I am quite possibly using wrong terms so someone else will have to explain it better.

 

[Red Fox Four]

I think the OP has been doing exploration for too long, then caught a case of cabin fever in his Asp and started to over-analyze things too much

Nah, just kidding.

It's an interesting question.

However, the moon is tidal locked to earth and always has the same side facing earth throughout it's full orbital cycle.

So the stations are tidal locked?

For more details on tidal locking... since I suck at explaining: http://en.wikipedia.org/wiki/Tidal_locking

** edit **

I think this image might help explain it (it's taken from the same tidal locking link though).

When the station (in our case) orbits so that its side is facing the planet, the gravitational forces will pull on the 'ends' and try to stabilize it. Like the image it shows the forces pulling along the F line

 

[DaveB]

The devs answered this one back in beta sometime. The stations are not tidally locked, they orbit the planet in a fixed orientation so yes, as the OP surmised, they face in a constant direction. There's been quite frequent posts of misinformation that the slot always faces the planet - this was true in the original '84 Elite but it is not true in ED.

 

[Red Fox Four]

If they rotate planet in a fixed orientation then they would need to constantly adjust using thrusters to counter gravitational forces ... ? Unless they are so far away from planet that this is not an issue... then again, gravity is always present in space, just varying amounts of force.

 

[DaveB]

If they rotate planet in a fixed orientation then they would need to constantly adjust using thrusters to counter gravitational forces ... ? Unless they are so far away from planet that this is not an issue... then again, gravity is always present in space, just varying amounts of force.

Nope. That's not what I meant by "fixed orientation" - They face the same way throughout their orbit. A station aligned towards the planet at perigee will face away from it at apogee.

 

[sqzbox1]

I'm not sure that y'all have quite grasped ALL of what the OP is saying. I think we all know what the devs have said - that the stations are not tidally locked and that orientation of the slot will depend on where it is in the orbit at the moment you approach. But what OP is saying is that after 3 months of playing regularly, by approaching the station from inside the orbit ALWAYS has got us looking at the slot - i.e. it has NEVER been facing outwards in all that time. I, too, have been wondering about that. Our experience over the course of the last 3 months flies in the face of what we have been told.

It's no biggie, and I actually am quite happy about it because it means I can always fly right to the slot without any issues. But it is somewhat curious - don't ya think?

 

[trilathon]

yes, I agree, they never directly seem to face the planet, and they never face directly away from the planet...it is always at a slight angle towards the planet.

 

[Red Fox Four]

Why would they not be tidally locked?

It makes more sense from a physics perspective to have them tidally locked, ie access corridor facing planet.

Otherwise you would need to constantly realign the orientation of the station using thrusters (so that the end with the access corridor always faces towards.. I dunno... the primary star, the Horsehead Nebula, Mecca, whatever).

Also, if the stations in original Elite all faced the planet, why wouldn't they now as well?

Regardless if what Elite devs have stated or said, if the access corridor of the stations in fact *are* facing the planet... then... I dunno... end of discussion?

 

[specialsymbol]

I think the OP has been doing exploration for too long, then caught a case of cabin fever in his Asp and started to over-analyze things too much

Nah, just kidding.

It's an interesting question.

However, the moon is tidal locked to earth and always has the same side facing earth throughout it's full orbital cycle.

So the stations are tidal locked?

For more details on tidal locking... since I suck at explaining: http://en.wikipedia.org/wiki/Tidal_locking

** edit **

I think this image might help explain it (it's taken from the same tidal locking link though).

When the station (in our case) orbits so that its side is facing the planet, the gravitational forces will pull on the 'ends' and try to stabilize it. Like the image it shows the forces pulling along the F line

View attachment 21631

No, because tidal locking means that one object is rotating synchronous with it's orbit around another planet (or at least in a natural ratio).
This is obviously not the case with stations.

The stations could be tidally locked, thus pointing always in direction of the planet - but then no rotation about their axis would be possible, as they're already rotating around an axis parallel to their orbit's. If they weren't they couldn't always be oriented in direction of the planet...

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Why would they not be tidally locked?

It makes more sense from a physics perspective to have them tidally locked, ie access corridor facing planet.

Otherwise you would need to constantly realign the orientation of the station using thrusters (so that the end with the access corridor always faces towards.. I dunno... the primary star, the Horsehead Nebula, Mecca, whatever).

Also, if the stations in original Elite all faced the planet, why wouldn't they now as well?

Regardless if what Elite devs have stated or said, if the access corridor of the stations in fact *are* facing the planet... then... I dunno... end of discussion?

They would not be tidally locked because they couldn't rotate about their own axis then.

 

[Red Fox Four]

Why would a rotation around their own axis not be possible even though the 'end' of the station is pointing towards the planet?

And if any rotation would be artificially induced, e.g. through use of thrusters it would be the rotation around it's own axis to create artificial gravity ?

 

[specialsymbol]

yes, I agree, they never directly seem to face the planet, and they never face directly away from the planet...it is always at a slight angle towards the planet.

I've seen stations almost directly face the planet, but never otherwise.

I've also seen stations with an orbiting period of a mere few hours, so I could observe them at various different points along their orbits - near enough to continuous (grinding).

 

[specialsymbol]

Why would a rotation around their own axis not be possible even though the 'end' of the station is pointing towards the planet?

And if any rotation would be artificially induced, e.g. through use of thrusters it would be the rotation around it's own axis to create artificial gravity ?

Conservation of momentum

Try riding a bicycle (fast) / motorcycle and then apply a steering input (turning the bars) in the direction you want to go. You'll tip over, because it's falling in the wrong way.
That's, by the way, how you steer a motorcycle: you turn the bars in the opposite direction of where you want to go.

The motorcycle doesn't that much steer in that direciton but tip over to the other side! Then the curved wheel will roll along, with the bigger diameter being on the outside of the turn and the smaller on the inside - just like an ice cone rolling in a circle.

Works the same with bicycles, but less pronounced. That's why kids fall when the training wheels come off, because before they did actually steer through turns. Now they need to lean and roll around turns.



Result of discourse: you can't change the plane of rotation without having the object tumble around. And you need an external force to do so.

 

[Inodoro Pereyra]

The devs answered this one back in beta sometime. The stations are not tidally locked, they orbit the planet in a fixed orientation so yes, as the OP surmised, they face in a constant direction. There's been quite frequent posts of misinformation that the slot always faces the planet - this was true in the original '84 Elite but it is not true in ED.

Sorry but since premium beta I never see a station (letterbox) pointing outside the planet. They never point directly, but +-30 degrees up/down the planet.
Satellites use 3 rotating wheels (reaction whells) to point in the desired direction; so Stations probably have this kind of devices to point where they need.

 

[shadragon]

It's a game.

They programmed it that way.

 

[Wile_E]

#14: The simplest and most accurate demonstration to this case would be to sit a person in a swivel chair. Then have the person extend his arms and put a bicycle wheel to his hands so that he holds on to the axle. Spin the wheel and start turning the swivel chair about it´s axis. If the wheel spins fast enough, the person won´t be able to hold onto the wheel or the chair becomes very hard to turn. By turning the chair you are changing the direction of the wheels rotation, which is exactly what happens with the stations if they rotate like they do in the Elite universe. It doesn´t matter if the rotation is so that the axis is towards the planet or in a 90 degree angle, it´s the change of direction of the rotating axis that requires work. The bigger the mass, the more work needed and for a coriolis station sized object the work needed would be phenomenal.

OFC the work needed to do the change could be produced by reaction wheels like said in post #15, but since the mass of the station is huge, the wheels would need to be huge and the current draw needed to turn them and the forces applied to their bearings would be huge as well.

 

[Chevy66]

Conservation of momentum


Result of discourse: you can't change the plane of rotation without having the object tumble around. And you need an external force to do so.

This is right, to have the slot always facing the planet it would need to use thrusters to keep it's rotation stable on it's own axis. It couldn't just orbit like that.

However maybe they do use thrusters? There's plenty of fuel about

 

[specialsymbol]

Sorry but since premium beta I never see a station (letterbox) pointing outside the planet. They never point directly, but +-30 degrees up/down the planet.
Satellites use 3 rotating wheels (reaction whells) to point in the desired direction; so Stations probably have this kind of devices to point where they need.

This only works for small corrections. You can of course make a satellite spin, but then the same rules apply again.

 

[Tryst]

The Earth's moon always presents the same face toward us does it not? That is because it does one rotation in the same time period as it's orbit, exactly as the station would do.

The station also rotates on a second axis to produce a small gravity inside the station. If the time frame were sped up and a fixed point from the station was used to observe, the station would appear to be tumbling.

Use FA off and start rotating the ship, then tap left or right yaw for a second and your ship would be doing exactly the same as the station does. In a game like this, where things can be set to absolute zero, it would keep going forever, in reality the tiny amount of friction in space would cause it to stop so it would need a little boost from the thrusters to keep it going occasionally.