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AmSteel is a high strength poly-ethylene fiber. Its strength passes that of stainless 316/8 and is considerably less mass per foot. A 4 inch piece could support a length of 160 miles if the documentation and my quick and dirty math are correct . Could this material be used to make an orbiting space tether?

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  • $\begingroup$ I am not sure what you mean by "a 4 inch piece could support a length of 160 miles". A 4 inch long fiber is 4 inches long... and 160 miles of fiber can be stressed at any level, just because you are in space doesn't mean that there are no inertial forces on it. $\endgroup$
    – CuriousOne
    Jul 1, 2015 at 16:54
  • $\begingroup$ 4 inch diameter. sorry hand injury. $\endgroup$
    – SkipBerne
    Jul 2, 2015 at 17:08
  • $\begingroup$ A practical space tether will most likely be a few mm in diameter. 4 inch cables hold up entire segments of bridges. $\endgroup$
    – CuriousOne
    Jul 2, 2015 at 18:37
  • $\begingroup$ Amsteel is not a cable. It is far superior, the strongest material made so far. The two basic issues are the ability to support its own mass (plus payload) and coupling pressure. A 4 inch dia line can almost lift a supertanker. We use a 3/4 inch one to lift locomotives. $\endgroup$
    – SkipBerne
    Jul 2, 2015 at 19:54
  • $\begingroup$ There is no need to lift supertankers in space. One doesn't have to lift anything, at all. :-) $\endgroup$
    – CuriousOne
    Jul 2, 2015 at 22:50

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In general, polymers are not a good idea as atomic oxygen and charged particles will eat them up. High density polyethylene, however, may form a protective oxidative coating against atomic oxygen (source). I would argue that it's still worth depositing a thin film of a metal that forms a nice protective oxide layer, e.g. Al, which would also prevent charge build up.

Also, it kind of depends on the purpose of the tether... for some applications you really want it to be electrically conductive, which polyethylene isn't.

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