|
A skyhook is a proposed momentum exchange tether that aims to reduce the cost of placing payloads into space. A heavy orbiting station is connected to a cable which extends down towards the surface. Payloads, which are much lighter than the station, are hooked to the end of the cable as it passes, and are then flung into orbit by rotation of the cable around the centre of mass. The station can then be reboosted to its original altitude by electromagnetic propulsion, rocket propulsion, or by deorbiting another object equal in mass to the payload. A skyhook differs from a geostationary orbit space elevator in that a skyhook would be much shorter and would not come in contact with the surface of the Earth. A skyhook would require a suborbital launch vehicle to reach its lower end, while a space elevator would not. ==History== Different synchronous non-rotating orbiting skyhook concepts and versions have been proposed, starting with Isaacs in 1966,〔See also: letter in ''Science'' 152:800, May 6, 1966.〕 Artsutanov in 1967,〔Artsutanov, Y. V Kosmos na Elektrovoze (Into Space by Funicular Railway). Komsomolskaya Pravda (Young Communist Pravda), July 31, 1960. Contents described in Lvov, ''Science'' 158:946, November 17, 1967.〕〔Arsutanov, Y. V Kosmos Bez Raket (Into Space Without Rockets). Znanije-Sile (Knowledge is Power) 1969(7):25, July, 1969.〕 Pearson and Colombo in 1975,〔Colombo, G., Gaposchkin, E. M., Grossi, M. D., and Weiffenbach, G. C., "The 'Skyhook': A Shuttle-Borne Tool for Low Orbital Altitude Research," ''Meccanica'', Vol. 10, No. 1, Mar. 1975.〕 Kalaghan in 1978,〔Kalaghan, P., Arnold, D. A. , Colombo, G., Grossi, M., Kirschner, L. R., and Orringer, O., "Study of the Dynamics of a Tethered Satellite System (Skyhook)," NASA Contract NAS8-32199, SAO Final Report, Mar. 1978.〕 and Braginski in 1985.〔V.B. Braginski and K.S. Thorne, "Skyhook Gravitational Wave Detector," Moscow State University, Moscow, USSR, and Caltech, 1985.〕 The version with best potential involve a much shorter tether in low Earth orbit which rotates in its orbital plane and whose ends brush the upper Earth atmosphere, with the rotational motion cancelling the orbital motion at ground level. These "rotating" skyhook versions were proposed by Moravec in 1976,〔 Presented at 23rd AIAA Meeting, The Industrialization of Space, San Francisco, CA,. October 18–20, 1977.〕 and Sarmont in 1994.〔 When the Italian scientist Giuseppe Colombo proposed in the early 1970s the idea of using a tidally stabilized tether for downward-looking Earth observation satellites, NASA officially begun to assess in 1979 the possible scientific applications for long tethers in space and whether the development of a tethered system was justified. This resulted in a Shuttle-based tether system: the TSS-1R mission, launched 22 February 1996 on STS-75 that focused in characterizing basic space tether behavior and space plasma physics.〔 The Italian satellite was deployed to a distance of from the Space Shuttle.〔 An engineer speculated in 1994 that the skyhook could be cost competitive with what is realistically thought to be achievable using a space elevator. In 2000 and 2001, Boeing Phantom Works, with a grant from NASA Institute for Advanced Concepts, performed a detailed study of the engineering and commercial feasibility of various skyhook designs. They studied in detail a specific variant of this concept, called "Hypersonic Space Tether Orbital Launch System" or HASTOL. This design called for a hypersonic ramjet or scramjet aircraft to intercept a rotating hook while flying at Mach 10. While no skyhook has yet been built, there have been a number of flight experiments exploring various aspects of the space tether concept in general. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Skyhook (structure)」の詳細全文を読む スポンサード リンク
|