Editing Megastructure (section)

===Trans-orbital structures===
[[File:SpaceElevatorClimbing.jpg|thumb|right|One concept for the [[space elevator]] has it tethered to a mobile seagoing platform.]]
{{Main|Non-rocket spacelaunch}}
* A [[Skyhook (structure)|skyhook]] is a very long tether that hangs down from orbit.
* A [[space elevator]] is a tether that is fixed to the ground, extending beyond geostationary orbital altitude, such that centripetal force exceeds gravitational force, leaving the structure under slight outward tension.
* A [[space fountain]] is a dynamically supported structure held up by the momentum of masses which are shot up to the top at high speeds from the ground.
* A [[launch loop]] (or Lofstrom loop) is a dynamically supported 2000&nbsp;km long iron loop that projects up in an arc to 80&nbsp;km that is ridden by [[Maglev (transport)|maglev]] cars while achieving orbital velocity.
* [[StarTram|StarTram Generation 2]] is a [[Maglev (transport)|maglev]] launch track extending from the ground to above 96% of the atmosphere's mass, supported by magnetic levitation.
* A [[Tether propulsion#Rotovators|rotovator]] is a rotating tether where the lower tip is moving in the opposite direction to the tether's orbital velocity, reducing the difference in velocity relative to the ground, and hence reducing the velocity of rendezvous; the upper tip is likewise moving at greater than orbital velocity, allowing propellantless transfer between orbits. Around an airless world, such as the Moon, the lower tip can actually touch the ground with zero horizontal velocity.<ref>[http://www.tethers.com/papers/LEO2Lunar%2792.pdf "Tether Transport From LEO To The Lunar Surface"] {{Webarchive|url=https://web.archive.org/web/20110517191711/http://www.tethers.com/papers/LEO2Lunar'92.pdf |date=2011-05-17 }}, [[Robert L. Forward]], 1991, 27th Joint Propulsion Conference, AIAA 91-2322</ref> As with any [[momentum exchange tether]], orbital energy is gained or lost in the transfer.