- Skyhook (structure)
Skyhooks are a type of hypothetical structure that would be used for
non-rocket spacelaunch intoorbit , for example, aspace elevator , continuously supporting it rather than using rockets, catapults or hypothetical anti-gravity effects. Smaller skyhooks includeorbital ring s with 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.The technique of hooking cargo on the ground or in the air with a capturing aircraft has been successfully used by the U.S. Air Force in the
Fulton surface-to-air recovery system . An extension of this technique is to use hypersonic aircraft. [http://72.14.253.104/search?q=cache:D0V5X5Eib5AJ:www.tethers.com/papers/HASTOLAIAAPaper.pdf+space+propulsion+skyhook&hl=en&ct=clnk&cd=25&gl=us Hypersonic Airplane Space Tether Orbital Launch (HASTOL) System: Interim Study Results] ]The name skyhook is a reference to an imaginary hook that hangs from the sky. See
tether propulsion for more details on various types of skyhooks.In Fiction
A form of hard-structure subsonic skyhook was constructed during the events of Jack McDevitt's novel "Deepsix".
In the anime , the three main protagonists arrive at the series' climactic battle with Galatea in Earth orbit by commandeering a skyhook transit system.
In
Yukito Kishiro 's mangaBattle Angel Alita , skyhooks are used to transport just about everything including preserved human body parts from the Scrapyard to Tiphares.Turn A Gundam, anime series, depicts an ancient hypersonic skyhook which has been maintained operationally by nanomachines over thousands of years. An ancient mass driver is also used for transporting space-vessels from earth's surface to the skyhook.Fact|date=July 2008
In the
Star Wars expanded universe , skyhooks are common aboveCoruscant . They are frequently private retreats owned by corporations or wealthy individuals.The planet of
Tara K. Harper 's "Grey Ones" series features a number of skyhook stations. The tethers are apparently no longer functioning, but large terminal structures still exist. They are used as a plot device, as ferrous weapons are impossible to use near the structures due to their intense magnetic fields.A skyhook figures prominently in
Arthur C. Clarke 's posthumous novelThe Last Theorem , which he co-wrote withFrederik Pohl . The novel describes the skyhook as a means of interplanetary travel rather than simply a means to reach orbit. It is used as a means of transport by athletes and delegates to the "first-ever lunar Olympics". [ [http://www.telegraph.co.uk/arts/main.jhtml?xml=/arts/2008/07/26/nosplit/boextract126.xml Extract: The Last Theorem by Arthur C Clarke and Frederik Pohl] ]The construction of skyhooks, including a
space elevator and several other orbital devices for launching craft into orbit and interplanetary travel, as well as decelerating and capturing craft on arrival, is a central theme in the science fiction novel "The Barsoom Project", the second book in theDream Park series, byLarry Niven andSteve Barnes . The destructive potential of a falling skyhook is also explored, and the potential for this to be exploited by terrorists.See also
*
Mass driver
*Railgun
*Space fountain
*Space elevator References
* A paper by
Hans Moravec : http://www.frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/papers/scable.pox
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