Editing Interplanetary spaceflight (section)

===Space elevator===
{{main|Space elevator}}
A space elevator is a theoretical structure that would transport material from a planet's surface into orbit.<ref>{{cite web|url=http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html |title=The Space Elevator Comes Closer to Reality |last=David |first=D |publisher=space.com |date=2002 |url-status=dead |archive-url=https://web.archive.org/web/20101104104658/http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html |archive-date=2010-11-04 }}</ref> The idea is that, once the expensive job of building the elevator is complete, an indefinite number of loads can be transported into orbit at minimal cost. Even the simplest designs avoid the [[vicious circle]] of rocket launches from the surface, wherein the fuel needed to travel the last 10% of the distance into orbit must be lifted all the way from the surface, requiring even more fuel, and so on. More sophisticated space elevator designs reduce the energy cost per trip by using [[counterweight]]s, and the most ambitious schemes aim to balance loads going up and down and thus make the energy cost close to zero. Space elevators have also sometimes been referred to as "[[Space elevator|beanstalks]]", "space bridges", "space lifts", "space ladders" and "orbital towers".<ref>{{Cite journal|last=Edwards|first=Bradley C.|date=2004|title=A Space Elevator Based Exploration Strategy|journal=AIP Conference Proceedings|volume=699|pages=854–862|doi=10.1063/1.1649650|bibcode=2004AIPC..699..854E}}</ref>

A terrestrial space elevator is beyond our current technology, although a [[lunar space elevator]] could theoretically be built using existing materials.