From: Monte Davis 

Leave it to Scots to see what can be done wi'oot paying for fuel.

http://news.scotsman.com/topics.cfm?tid=6&id=506212006
http://news.scotsman.com/topics.cfm?tid=6&id=510172006

The reporter garbles the physics, but this idea has been around for decades
as the rotovator. Instead of the "beanstalk" space elevator
anchored to a planet, this would be in orbit, rotating like a bola around
its own center of mass. It doesn't demand as strong a material as the SE,
although the stronger the better (faster spin = greater tension).

At first you'd use some efficient, low-thrust method like an ion engine to
spin it up gradually between launches. Later, when there's traffic both
ways, you can recapture energy from incoming loads. It's the most elegant
space propulsion ever: keep using the same momentum over and over, trading
it around the solar system, instead of throwing away half of it in rocket
exhaust on every trip.

Some variations use it to ease the earth-to-orbit challenge by orbiting the
tether low enough that a very fast very high plane could transfer payloads.
Me, I get itchy whenever I hear "very fast very high plane," for
this or as a flyback first stage for rockets; when you do the math it
always seems that you're solving one tough expensive problem (high cost to
orbit) by presuming the solution of another ('way-beyond-Blackbird
airbreathing flight).

NB that the "beanstalk" SE could sling cargo very nicely from its
outer segment beyond GEO -- enough free momentum there, tapping the earth's
angular momentum, to get anywhere from Venus to the asteroids. ( Insert
lengthening-of-day jokes here.)

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