Space Elevator

There has been discussion of finding the best way to get people and cargo into space. Right now, we strap people into a rocket and use as much thrust as can be mustered on that rocket to achieve low-Earth orbit. One of the ways that is physically possible, though the engineering may be a little off, is a space elevator, first proposed by Russian Konstantin Tsiolkovsky.


A space elevator is basically what it sounds like. It is a way to lift people and cargo into space into a geostationary/geosynchronous orbit using some sort of transport vehicle moving along a track into space. The question is what kind of propulsion can the transport use and what material will be used for the track?


First of all, what makes a space elevator a space elevator? The space elevator will have two end stations, one at the equator and one at a geostationary orbit above the Earth-bound station. Remember from our discussion on geostationary orbits that these are orbits that keep a satellite in the same location above the Earth at all times. More on these orbits can be found here. The station on Earth has to be at the equator because the station in space has to remain in the same location, and geostationary orbits require points above the Earth's equator. It is possible to have way stations along the path, but these way stations must have continuous propulsion to remain in place.


Space elevators can be made out of a material called carbon nanotubes (which are theoretical). These tubes would have the property of being both lightweight and strong. The track material must withstand large tensions and torsional forces to prevent breaking. The preferred method of propulsion would be magnetic forces, much like a maglev train uses magnetic repulsion to move them at high speeds.


The station on the end of the elevator in space will have to be at 35,786 km above the equator because it is a geostationary object. This also means that if somehow the elevator did break, it would wrap around the Earth more than once since the circumference of the Earth is only ~25,000 km.


So the physics is there to make space elevators a reality, but unfortunately, the engineering has not quite caught up. If we were able to build one, the cost of launching objects into space would be decreased immensely.