I wonder does is possible to dock to rotating space craft?

[Pawelk198604]

You probably know to which i referring to ;)
[video=youtube;GhlU3ikw8sA]https://www.youtube.com/watch?v=GhlU3ikw8sA[/video]

I seen this in Kubrick 2001 Space Odyssey and even in one KSP video
But i wonder does is possible to do this with real spacecraft, i have real problem with docking in KSP with relatively stable object not rotating 67-68 RPM

[problemecium]

Yeah. As a matter of fact a lot of us KSPers, when watching that scene, were thinking "okay this is exciting and gets across to the masses how hard docking is, but psh. I've done that before."

It's a lot harder to do manually compared to a stationary target, but it can still be done with some patience, and with an automatic guidance system it can be pretty straightforward.
This is true in both KSP and real life, although for obvious reasons people take every measure to not have to do it in real life ;)

[Kerbart]

If the axis of the docking port and the axis of rotation are the same, it would be fairly easy, just a little bit more work.

If the axis of the docking port and the axis of rotation are offset but parallel (aligned), it would be a lot harder and I doubt a lot of players could pull it off (I know I wouldn't).

If the axis of the docking port and the axis of rotation are not aligned... well, good luck with that!

[G'th]

Sure it is. If you can match your target's movement that is. The real issue is how practical it is to do so, as it can end catastrophically if you don't do it just right. Real docking mechanisms require more than just bumping up against each other like in KSP, and if you mess it up at such a high speed, well, you're not coming back from space today. :)

In 2001, the station isn't moving all that fast and and it was only spinning on one axis. Furthermore, docking while rotating also provides the benefit of not having to construct both a fixed docking module and some sort of mechanism to get the passengers moving with the station. Gravity gets introduced as the ship begins to dock and passengers can just walk through the door. And given the futuristic technology present, fuel isn't a big deal so its not like their wasting tremendous amounts of fuel trying to match the rotation.

Interstellar is a bit iffy, but more because of what caused the Endurance to spin than the impracticality of docking with a spacecraft that is that out of control (though with the circumstances they didn't really have a choice, they were dead if they didn't try). That explosion even as they showed it should have introduced far more than just a single axis spin. But again, futuristic spacecraft. The Rangers and Landers only ran out of fuel when the story said they needed to. But even so, not necessarily impossible if you're still able to match the target.

Even getting the Endurance under control wouldn't have been impossible once you docked. Though I don't know if they actually showed Cooper doing it, they could easily have tapped into the RCS of the Endurance itself to help bring it under control once they were docked.

[Sampa]

Yeah, in this case, I say it is plausible. Impractical, but plausible. The trick is to match relative velocity, includingvelocity of the spin itself!

[Pawelk198604]

[QUOTE=G'th;2304791]Sure it is. If you can match your target's movement that is. The real issue is how practical it is to do so, as it can end catastrophically if you don't do it just right. Real docking mechanisms require more than just bumping up against each other like in KSP, and if you mess it up at such a high speed, well, you're not coming back from space today. :)

In 2001, the station isn't moving all that fast and and it was only spinning on one axis. Furthermore, docking while rotating also provides the benefit of not having to construct both a fixed docking module and some sort of mechanism to get the passengers moving with the station. Gravity gets introduced as the ship begins to dock and passengers can just walk through the door. And given the futuristic technology present, fuel isn't a big deal so its not like their wasting tremendous amounts of fuel trying to match the rotation.

Interstellar is a bit iffy, but more because of what caused the Endurance to spin than the impracticality of docking with a spacecraft that is that out of control (though with the circumstances they didn't really have a choice, they were dead if they didn't try). That explosion even as they showed it should have introduced far more than just a single axis spin. But again, futuristic spacecraft. The Rangers and Landers only ran out of fuel when the story said they needed to. But even so, not necessarily impossible if you're still able to match the target.

Even getting the Endurance under control wouldn't have been impossible once you docked. Though I don't know if they actually showed Cooper doing it, they could easily have tapped into the RCS of the Endurance itself to help bring it under control once they were docked.[/QUOTE]

[quote name='Sampa']Yeah, in this case, I say it is plausible. Impractical, but plausible. The trick is to match relative velocity, includingvelocity of the spin itself![/QUOTE]

And they would not be the whole situation if it were not stupid robot that has disabled the automatic docking mechanism in the Dr. Mann spaceship ;)

[G'th]

IF it wasn't for that stupid robot they would have been stranded on an uninhabitable planet.

And besides, story wise Mann trying to steal the Endurance was necessary. Some of the greater themes in the story had to do with the different attitudes people have towards such dire situations. Some just want to be with their families no matter what happens. Some don't care if the rest die if they survive. Some refuse to face the reality of their situation.

Mann was a coward who jeopardized the entire mission because he couldn't face dying alone. Even Cooper, who just plain wanted to go back home, still didn't jeopardize the mission because of it, even when it became apparent he wouldn't get to.

[SomeGuy12]

If you wanted to dock to a rotating station along the rim, cuz you're crazy...can it be done?

Let's see...if you draw an imaginary line out in space representing a tangent coming off the rim, and then position your spacecraft along that line, I think it would become an intercept problem. Suppose there's a particular docking port that passes a point on the tangent line with every revolution. You want to match velocities with the rim speed, and then arrive at the intersect point between the tangent line, the station, and the docking port at exactly the right instant. Assuming constant station velocity and a known distance, this is a pretty simple intercept problem.

So you just jet on over, matching velocity during the initial burn, then at the very instance your docking apparatus (something that can grab really fast, like big honking electromagnets I guess) achieves closest approach to the station, at that exact same instance, the docking port revolves underneath it.

A gigantic surge of current and the magnet sticks you to the station.

The problem is you go from 0 acceleration (just coasting through space headed for the rendevouz) to 1 G instantly. A huge jerk. It seems like this might also be bad for the structure of your spacecraft and the station. Maybe shock absorbers could smooth it out?

On the bright side, the actual rendevouz is easy. You can trivially monitor the relative position of the station wheel as you approach on computer control, via optically checking against markings on the wheel. Radars give your exact velocity of approach. You can easily fine tune your approach as you get closer, and if something happens to where the rendevouz will be missed, you just need a puff of RCS to push you away from the station so the closest approach is more than 10 meters separation. The timing is only difficult if humans have to do it. The hard part is the mechanical coupling and the whiplash. Edited November 19, 2015 by SomeGuy12

[Findthepin1]

The axis of rotation have to be the same on both ships. The axis of rotation must go almost perfectly through the centre of the docking ports on both ships. The ships must both be rotating at the same speed at any given distance from the axis of rotation.

[Bill Phil]

It's doable all right. Difficult, but doable. The only real requirements for a docking are having very little relative velocity, with most of it going towards the target.

[WestAir]

Could you dock with the wheel of a rotating wheel space station?

[Laie]

[quote name='WestAir']Could you dock with the wheel of a rotating wheel space station?[/QUOTE]

Short answer: yes.

As you apparently don't know 'em, watch these classics: Docking scene from 2001...
[video=youtube;q3oHmVhviO8]https://www.youtube.com/watch?v=q3oHmVhviO8[/video]

[video=youtube;X0czVxiEqNM]https://www.youtube.com/watch?v=X0czVxiEqNM[/video]
...and Elite. That guy nearly wrecks his craft, but hey. Edited November 20, 2015 by Laie

[Bill Phil]

[quote name='Laie']Short answer: yes.

As you apparently don't know 'em, watch these classics: Docking scene from 2001...
[URL]https://www.youtube.com/watch?v=q3oHmVhviO8[/URL]

[URL]https://www.youtube.com/watch?v=X0czVxiEqNM[/URL]
...and Elite. That guy nearly wrecks his craft, but hey.[/QUOTE]

I think he meant the outer wheel...

[Findthepin1]

Try it in KSP.

[WestAir]

[quote name='Bill Phil']I think he meant the outer wheel...[/QUOTE]

I did.

[I]I edited my post because my initial response wasn't polite, and there's never a reason to be impolite.[/I] Edited November 20, 2015 by WestAir

[Whirligig Girl]

When I first saw Interstellar I was biting my nails and my tongue trying not to yell "I HAD TO DO THAT ONCE!"

Except when I did it it was slower and it was a pitch/yaw rotation, not a roll rotation. This made it much more difficult than when I tried it again with a rapid roll after seeing the movie.

[wumpus]

You would probably need much better computer assistance than presently available. You would have to align everything exactly right just before the moment of docking, then dock. Every additional attempt would require the same docking pattern (no "just keep getting closer"). It could be done, but the timing requirements would be difficult.

If you can dock Abyssal Lurker style (feet only, or spacebar only), you can likely dock on an outer wheel. I can't.

[Armchair Rocket Scientist]

[quote name='SomeGuy12']If you wanted to dock to a rotating station along the rim, cuz you're crazy...can it be done?

Let's see...if you draw an imaginary line out in space representing a tangent coming off the rim, and then position your spacecraft along that line, I think it would become an intercept problem. Suppose there's a particular docking port that passes a point on the tangent line with every revolution. You want to match velocities with the rim speed, and then arrive at the intersect point between the tangent line, the station, and the docking port at exactly the right instant. Assuming constant station velocity and a known distance, this is a pretty simple intercept problem.

So you just jet on over, matching velocity during the initial burn, then at the very instance your docking apparatus (something that can grab really fast, like big honking electromagnets I guess) achieves closest approach to the station, at that exact same instance, the docking port revolves underneath it.

A gigantic surge of current and the magnet sticks you to the station.

The problem is you go from 0 acceleration (just coasting through space headed for the rendevouz) to 1 G instantly. A huge jerk. It seems like this might also be bad for the structure of your spacecraft and the station. Maybe shock absorbers could smooth it out?

On the bright side, the actual rendevouz is easy. You can trivially monitor the relative position of the station wheel as you approach on computer control, via optically checking against markings on the wheel. Radars give your exact velocity of approach. You can easily fine tune your approach as you get closer, and if something happens to where the rendevouz will be missed, you just need a puff of RCS to push you away from the station so the closest approach is more than 10 meters separation. The timing is only difficult if humans have to do it. The hard part is the mechanical coupling and the whiplash.[/QUOTE]

Docking with the rim of a rotating station would be incredibly easy. Just make the rim significantly wider than the spokes, or build it without a hub. Then put maglev rails on the inner rim. The docking spacecraft maneuvers up to the rails as slowly and carefully as it wants, then clamps onto the rails and a braking system on the station automatically slows it down, at which point it is switched off the main rails to a docking bay. For undocking, the process occurs in reverse, with the spacecraft being catapulted backwards until its "true" velocity is zero, then unclamp from the rails and fly off with RCS. Heck, you could even build an actual runway on a station and land a spaceplane on it, although taking off would still need a catapult.

[SomeGuy12]

[quote name='Armchair Rocket Scientist']Docking with the rim of a rotating station would be incredibly easy. Just make the rim significantly wider than the spokes, or build it without a hub. Then put maglev rails on the inner rim. The docking spacecraft maneuvers up to the rails as slowly and carefully as it wants, then clamps onto the rails and a braking system on the station automatically slows it down, at which point it is switched off the main rails to a docking bay. For undocking, the process occurs in reverse, with the spacecraft being catapulted backwards until its "true" velocity is zero, then unclamp from the rails and fly off with RCS. Heck, you could even build an actual runway on a station and land a spaceplane on it, although taking off would still need a catapult.[/QUOTE]

Yeah that's an enormously better idea. A continuous ring of maglev track is enormously easier to couple to than a moving point on the station ring. As a practical solution it's so much better the method I proposed isn't even worth considering, since it also eliminates the jerk of a sudden grab of a heavy spacecraft.

Also you could do the docking purely manually. Ironically, it would possibly be easier to pull off than doing docking in KSP right now.

[Pawelk198604]

But if not CASE who disabled the automatic docking it would be happened ;)

[Phineas Freak]

As the case of Salyut 7 has shown, it is possible to dock to a rotating spacecraft. Not easy but as others have said, possible.

Edited May 21, 2016 by Phineas Freak

[ment18]

The last mission in space agency requires the user to dock with a slowly spinning and translating space shuttle.

[SomeGuy12]

If it's multi-axis spin, is it even possible, or are you out of luck?

I guess my "tangential tip velocity matching" proposal would work. You would "just" need a more sophisticated computer model to predict where the desired capture point will be in an hour or so. You set up a velocity matching burn and fly on an intercept course, such that you reach the desired capture point at the right moment in time, reaching closest approach at that moment.

The capture point has to be an object that is far from the spacecraft - the end of a boom or something. No hub docking possible, generally.

And this is not possible at all if the tumbling spacecraft is continuing to leak gas (probable way it got this way) and thus the numbers are changing.

[Laie]

[quote name='Bill Phil']I think he meant the outer wheel...[/QUOTE]
[quote name='WestAir']I did.[/QUOTE]

Well in that case, sorry for the distraction.

Of course you can dock to the outer wheel. Strictly speaking, you can dock anywhere: all you need to do is match velocities. In this case, you need a craft that can easily go in circles. It will require a lot of fuel and presumably more RCS thrust than one usually brings along. Controlling it is bound to be exciting. So all things considered, the proposition makes for a good challenge. But possible? Absolutely.

[WestAir]

[quote name='Laie']Well in that case, sorry for the distraction.

Of course you can dock to the outer wheel. Strictly speaking, you can dock anywhere: all you need to do is match velocities. In this case, you need a craft that can easily go in circles. It will require a lot of fuel and presumably more RCS thrust than one usually brings along. Controlling it is bound to be exciting. So all things considered, the proposition makes for a good challenge. But possible? Absolutely.[/QUOTE]

Sounds like material for a KSP challenge to me!