Skyhook (structure)

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For other uses, see Skyhook (disambiguation).

Skyhooks are hypothetical structures used for transporting material to and from a planet's surface into orbit, continuously supporting it rather than using rockets, catapults or hypothetical anti-gravity effects. The largest and perhaps simplest of these is the space elevator, a cable that runs all the way from the planet's surface to beyond geosynchronous orbit. Smaller skyhooks include hypersonic skyhooks, rotating cables in lower orbits whose ends dip repeatedly down close to the planet's surface to snag payloads and lift them up. Large rotating tethers can also be used far from a planet's surface to transfer momentum to and from payloads, changing their orbits without the expenditure of reaction mass.

See tether propulsion for more details on various types of skyhooks.