Editing Space elevator (section)

==Related concepts==
The conventional current concept of a "Space Elevator" has evolved from a static compressive structure reaching to the level of GEO, to the modern baseline idea of a static tensile structure anchored to the ground and extending to well above the level of GEO. In the current usage by practitioners (and in this article), a "Space Elevator" means the Tsiolkovsky-Artsutanov-Pearson type as considered by the International Space Elevator Consortium. This conventional type is a static structure fixed to the ground and extending into space high enough that cargo can climb the structure up from the ground to a level where simple release will put the cargo into an [[orbit]].<ref>"CLIMB: The Journal of the International Space Elevator Consortium", Volume 1, Number 1, December 2011, This journal is cited as an example of what is generally considered to be under the term "Space Elevator" by the international community. [http://www.isec.org/index.php?option=com_content&view=article&id=28&Itemid=31] {{Webarchive|url=https://web.archive.org/web/20131218085857/http://www.isec.org/index.php?option=com_content&view=article&id=28&Itemid=31|date=18 December 2013}}.</ref>

Some concepts related to this modern baseline are not usually termed a "Space Elevator", but are similar in some way and are sometimes termed "Space Elevator" by their proponents. For example, [[Hans Moravec]] published an article in 1977 called "A Non-Synchronous Orbital [[Skyhook (structure)|Skyhook]]" describing a concept using a rotating cable.<ref>{{cite journal |author=Moravec, Hans P. |title=A Non-Synchronous Orbital Skyhook|journal=Journal of the Astronautical Sciences|volume=25 |date=October–December 1977|bibcode=1977JAnSc..25..307M|pages=307–322}}</ref> The rotation speed would exactly match the orbital speed in such a way that the tip velocity at the lowest point was zero compared to the object to be "elevated". It would dynamically grapple and then "elevate" high flying objects to orbit or low orbiting objects to higher orbit.

The original concept envisioned by Tsiolkovsky was a compression structure, a concept similar to an [[Radio masts and towers|aerial mast]]. While such structures might reach [[Karman line|space]] (100&nbsp;km, 62&nbsp;mi), they are unlikely to reach geostationary orbit. The concept of a Tsiolkovsky tower combined with a classic space elevator cable (reaching above the level of GEO) has been suggested.<ref name="JBIS1999"/> Other ideas use very tall compressive towers to reduce the demands on launch vehicles.<ref name="TorontoProposal"/> The vehicle is "elevated" up the tower, which may extend as high as [[Karman line|above the atmosphere]], and is launched from the top. Such a tall tower to access near-space altitudes of {{cvt|20|km|mi}} has been proposed by various researchers.<ref name="TorontoProposal">{{cite journal |last1=Quine |first1=B. M. |last2=Seth |first2=R. K. |last3=Zhu |first3=Z. H. |year=2009 |title=A free-standing space elevator structure: A practical alternative to the space tether |url=http://pi.library.yorku.ca/dspace/bitstream/handle/10315/2587/AA_3369_Quine_Space_Elevator_Final_2009.pdf |journal=Acta Astronautica |volume=65 |issue=3–4 |page=365 |bibcode=2009AcAau..65..365Q |citeseerx=10.1.1.550.4359 |doi=10.1016/j.actaastro.2009.02.018}}</ref><ref>{{Cite book |doi = 10.2514/6.1998-3737|chapter = Compression structures for Earth launch |title = 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit|year = 1998|last1 = Landis|first1 = Geoffrey}}</ref><ref>Hjelmstad, Keith, [http://hieroglyph.asu.edu/wp-content/uploads/2014/08/Hjelmstad-on-Stephenson-Structural-Design-of-the-Tall-Tower.pdf "Structural Design of the Tall Tower"], ''Hieroglyph'', 30 November 2013. Retrieved 1 September 2015.</ref>

The aerovator is a concept invented by a Yahoo Group discussing space elevators, and included in a 2009 book about space elevators. It would consist of a >1000 km long ribbon extending diagonally upwards from a ground-level hub and then levelling out to become horizontal. Aircraft would pull on the ribbon while flying in a circle, causing the ribbon to rotate around the hub once every 13 minutes with its tip travelling at 8 km/s. The ribbon would stay in the air through a mix of [[aerodynamic lift]] and centrifugal force. Payloads would climb up the ribbon and then be launched from the fast-moving tip into orbit.<ref>{{Citation |last=Van Pelt |first=Micheal |title=Space Elevators |date=2009 |work=Space Tethers and Space Elevators |pages=143–178 |editor-last= |editor-first= |url=https://doi.org/10.1007/978-0-387-76556-3_6 |access-date=2023-12-27 |place=New York, New York |publisher=Springer |language=en-us |doi=10.1007/978-0-387-76556-3_6 |isbn=978-0-387-76556-3|url-access=subscription }}.</ref>

Other concepts for [[non-rocket spacelaunch]] related to a space elevator (or parts of a space elevator) include an [[orbital ring]], a [[space fountain]], a [[launch loop]], a [[Skyhook (structure)|skyhook]], a [[space tether]], and a buoyant "SpaceShaft".<ref>{{Cite web |title=Space Shaft: Or, the story that would have been a bit finer, if only one had known.... |url=https://ksj.mit.edu/tracker-archive/space-shaft-or-story-would-have-been-bit/ |access-date=2024-04-18 |website=Knight Science Journalism @MIT |language=en-US}}</ref>