Editing Skyhook (structure) (section)

==History==

Different synchronous non-rotating orbiting skyhook concepts and versions have been proposed, starting with Isaacs in 1966,<ref name=":0">{{Cite journal
 | pmid = 17813792
| year = 1966
| last1 = Isaacs
| first1 = J. D.
| title = Satellite elongation into a true "sky-hook"
| journal = Science
| volume = 151
| issue = 3711
| pages = 682–3
| last2 = Vine
| first2 = A. C.
| last3 = Bradner
| first3 = H
| last4 = Bachus
| first4 = G. E.
| s2cid = 32226322
| doi = 10.1126/science.151.3711.682
| bibcode = 1966Sci...151..682I
}}</ref><ref>See also: letter in ''Science'' 152:800, 6 May 1966.</ref> [[Yuri Artsutanov|Artsutanov]] in 1967,<ref>Artsutanov, Y. V Kosmos na Elektrovoze (Into Space by Funicular Railway). Komsomolskaya Pravda (Young Communist Pravda), 31 July 1960. Contents described in Lvov, ''Science'' 158:946, 17 November 1967.</ref><ref>Arsutanov, Y. V Kosmos Bez Raket (Into Space Without Rockets). Znanije-Sile (Knowledge is Power) 1969(7):25 July 1969.</ref> Pearson<ref>{{cite journal | last1 = Pearson | first1 = J | year = 1975 | title = The Orbital Tower: A Spacecraft Launcher Using the Earth's Rotational Energy | doi = 10.1016/0094-5765(75)90021-1 | journal = Acta Astronautica | volume = 2 | issue = 9–10| pages = 785–799 |bibcode = 1975AcAau...2..785P | citeseerx = 10.1.1.530.3120 }}</ref> and Colombo in 1975,<ref>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.</ref> Kalaghan in 1978,<ref>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.</ref> and Braginski in 1985.<ref>V.B. Braginski and K.S. Thorne, "Skyhook Gravitational Wave Detector," Moscow
State University, Moscow, USSR, and Caltech, 1985.</ref> The versions with the 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,<ref>{{cite web |title=Skyhook proposal |date=1976 |first=Hans |last=Moravec |author-link=Hans Moravec |url=http://www.frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/papers/scable.pox }}</ref><ref>{{cite journal | last1 = Moravec | first1 = H. P. | year = 1977 | title = A Non-Synchronous Orbital Skyhook | journal = Journal of the Astronautical Sciences | volume = 25 | pages = 307–322 |bibcode = 1977JAnSc..25..307M }} Presented at 23rd AIAA Meeting, The Industrialization of Space, San Francisco, CA,. 18-20 October 1977.</ref> and Sarmont in 1994.<ref name="sae.942120"/><ref>{{cite web |title=Skyhook proposal |date=1981 |first=Hans |last=Moravec |author-link=Hans Moravec |url=http://www.frc.ri.cmu.edu/~hpm/project.archive/general.articles/1981/high.wire/high.wire.html }}</ref>

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 physics|space plasma physics]].<ref name="sao.1997">{{cite book|last1=Cosmo|first1=M.|url=http://www.tethers.com/papers/tethersinspace.pdf|title=Tethers in Space Handbook|last2=Lorenzini|first2=E.|date=December 1997|publisher=Smithsonian Astrophysical Observatory|edition=Third|access-date=2014-04-18|archive-date=2007-10-06|archive-url=https://web.archive.org/web/20071006101028/http://www.tethers.com/papers/TethersInSpace.pdf|url-status=dead}}</ref> The Italian satellite was deployed to a distance of {{convert|19.7|km|mi|abbr=on}} from the Space Shuttle.<ref name="sao.1997"/>

Sarmont theorized in 1994 that the skyhook could be cost competitive with what is realistically thought to be achievable using a space elevator.<ref name="sae.942120">{{Cite book | doi=10.4271/942120| chapter=How an Earth Orbiting Tether Makes Possible an Affordable Earth-Moon Space Transportation System| title=SAE Technical Paper Series |volume=942120 | year=1994| last1=Sarmont| first1=Eagle}}</ref>

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 Airplane 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 number|Mach]] 10.<ref name="Boeing.2000">{{cite conference|last1=Bogar|first1=Thomas J.|last2=Bangham|first2=Michal E.|last3=Forward|first3=Robert L.|last4=Lewis|first4=Mark J.|date=7 January 2000|title=Hypersonic Airplane Space Tether Orbital Launch System, Research Grant No. 07600-018, Phase I Final Report|url=http://www.niac.usra.edu/files/studies/final_report/355Bogar.pdf|publisher=NASA Institute for Advanced Concepts|access-date=2019-07-07}}</ref>

In 2007, a student-built satellite called [[Young Engineers' Satellite 2|Young Engineers' Satellite 2 (YES2)]], part of [[ESA]]'s [[Foton-M3]] [[microgravity]] mission, deployed a 31.7 km tether. This was the longest tether ever deployed in space and officially set the Guinness world record<ref>{{Cite news |title=Longest space tether |url=https://www.guinnessworldrecords.com/world-records/longest-space-tether |archive-url=http://web.archive.org/web/20240528211022/https://www.guinnessworldrecords.com/world-records/longest-space-tether |archive-date=2024-05-28 |access-date=2025-02-16 |work=Guinness World Records |language=en-GB}}</ref>

While no skyhook has yet been built, there have been a number{{Quantify|date=May 2021}} of flight experiments exploring various aspects of the [[space tether]] concept in general.<ref name="Chen.2013">{{cite journal |title=History of the Tether Concept and Tether Missions: A Review |journal=ISRN Astronomy and Astrophysics |date=2013 |first1=Yi |last1=Chen |first2=Rui |last2=Huang |first3=Xianlin |last3=Ren |first4=Liping |last4=He |first5=Ye |last5=He |volume=2013 |doi=10.1155/2013/502973 |issue=502973 |pages=502973|bibcode=2013ISRAA2013E...2C |doi-access=free }}</ref>