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Imagine a winch pulling a rope or cable through a series of pulleys
(horizontal) that are staked to the ground. The pulleys are arranged so that
the rope makes a zig zag pattern on the ground. There is an object at one
end of the cable, being reeled in by the winch at the other end (ignore for
now that the object would collide with the pulleys)
The pulleys and winch stay in place because they are anchored to the ground.
Now imagine this setup on a much larger scale in space. The pulleys and
Winch, no longer tethered to anything, would not be able to stay in the same
spot.
But what if the winch and pulleys had thrusters on them to maintain their
position? Is that possible?
Start with the winch. It's reeling in the object at the other end of the
cable. In my mind the winch would also reel it's self in, so that it and
the object would meet in the middle. If it had thrusters, in this case
aimed towards the object, could it maintain it's position if it supplied
thrust which was equal in energy to the pulling of the cable? Disregard
fuel use etc.. Imagine that the thrusters could maintain a constant rate
throughout the reeling process.
So now think about the smaller pulleys that are spaced out along the cable.
In order for them to maintain the precise zig zag pattern (this is crucial)
they would need thrusters too. I imagine if they didn't have them the winch
and object would eventually pull the length of the cable straight.
Imagine for a moment that this is possible. The small pulleys would
disengage and shoot away (or explode perhaps) from the cable just before the
object hit them. This would correct the course of the object. ex: It was
going left, now it's going up and to the right, on its way to the next
pulley.
Thoughts?
[ j o n ]
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Message has 9 Replies:
 | | Re: A space physics question
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| (...) ... (...) It would be far more efficient to attach thrusters to the object being winched and move it to that location - or, if that is not possible, attach the tether line (which you've got on your object being moved) to a tow ship. Assuming (...) (22 years ago, 28-Dec-02, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| "Jon Palmer" <jon@zemi.net> skrev i meddelandet news:H7uLH0.I7r@lugnet.com... (...) the (...) This is where the force equations will hit you hard :-) The next pulley will suddenly get a great force through the line, and needs to increase it's thrust (...) (22 years ago, 28-Dec-02, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| (...) it's all relative isn't it. you could set up a thruster system to ensure that your anchor point wouldn't move, relatively. (...) yes, again, this is possible the key here is that you zig zag points stay the required distance apart. (...) this (...) (22 years ago, 29-Dec-02, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| (...) I'll say "sure" but with this question as a follow-up. Pulleys are usually used on Earth to gain a mechanical advantage. In space, since the object is weightless (but still has mass!) there isn't the need for the pulleys... at least as far as (...) (22 years ago, 29-Dec-02, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| (...) weight in space so we'll talk in inertia or mass. If you are a single person winching a large object such as a ship or asteroid or other large mass... then if we apply Einstein's space-time theory the object with the larger mass will move less (...) (22 years ago, 29-Dec-02, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| (...) Imagine a thread. A really interesting thread. The thread gets started but is arranged in a linear fashion, so that none of the responses are responded to. Apparently linear isn't as interesting as a zig zag pattern, so the thread appears to (...) (22 years ago, 10-Jan-03, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| (...) SNIP (...) Why not just artificial singularities instead of pulleys? Place pairs of singularities orbiting around each other in a ring pattern. the orbital plane of each pair is perpendicular & equidistant to the center anchor singularity. (...) (22 years ago, 10-Jan-03, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| (...) Great job on the .space page so far! A few points first: - in the absence of gravity, the force on the pulleys will only exist if the object in tow is continuously accelerating. Remember, accelerating can mean following a curved path as well (...) (22 years ago, 10-Jan-03, to lugnet.off-topic.geek, lugnet.space)
| | | Re: A space physics question
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| (...) Great job on the .space page so far! A few points first: - in the absence of gravity, the force on the pulleys will only exist if the object in tow is continuously accelerating. Remember, accelerating can mean following a curved path as well (...) (22 years ago, 10-Jan-03, to lugnet.off-topic.geek, lugnet.space)
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