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The way soldiers meet a wall in an obstacle run; they boost 1 or 2 of the team up to the top and then those up there help pull their colleagues up and over.

Just wondered if there might be a way something could be constructed in LEO that could help pull other systems up (not necessarily all the way). I suppose in my head I'm imagining something equivalent to a kind of immensely powerful magnet similar to those used in MRI, but are there any other thoughts or ideas along these lines being, or have been, considered?

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closed as too broad by Brian Tompsett - 汤莱恩, Hohmannfan Jun 9 '17 at 8:13

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ There are a lot of ideas for this: space elevators, skyhooks, maglev launch loops, etc etc etc. $\endgroup$ – Nathan Tuggy Jun 2 '17 at 19:14
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    $\begingroup$ The immensely powerful magnets used in MRI will move steel tools in the same room, but not in the next building. $\endgroup$ – Uwe Jun 2 '17 at 19:32
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Most such schemes you might envision won't accomplish anything useful.

Because of Newton's third law, any assistance given to the launching vehicle would pull down the helper in LEO, reducing the latter's momentum by the same amount of momentum given to the former.

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The primary issue is that getting into orbit is mostly a matter of velocity/kinetic energy, not height. The craft pulling would be slowed down, and the thrust required to get it and the new craft into the pulling craft's orbit would be the same as the thrust required to get the new craft into orbit without help.

There are some ideas to use tethers attached to large masses, as a suborbital craft could grab onto a tether moving at zero relative velocity and then climbing up to orbit. This depends on there being a much, much larger mass in orbit. Example: Phobos tether.

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As was mentioned by NathanTuggy in the comments, there are a number of proposals for ways of getting into orbit without rockets. They include Space Elevators, Sky Hooks, Mass Drivers, and Launch Loops.

I strongly recommend taking a look at the Upward Bound series of YouTube videos which covers these and more. They are produced by Isaac Arthur (home page), and IMHO they are of very good quality. They are all grounded in physics rather than fantasy and are more detailed than anything on cable tv. Each system is given about 30 min and considers how each may be implemented, and what can be done with existing technology and what cannot. (The economic aspect is put aside)

Aside from orbital systems his videos cover a number of other topics for those interested in the far reaches of space exploration. Highly recommended

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