The space elevators are closer than we think.

A space elevator is a system that pulls payload to the orbiter without a rocket engine. Three versions of that system could be realistic. Two of them require an electric engine, that is connected to the winch to raise the payload to the orbiter.

And the third one that bases on the asteroid that anchored to a geostationary position on the equator. The third one could be too complicated for the practical solution but the two first have potential. The requirement for a successful winch system is nontechnical ropes that could be light enough that they do not break structures. 

1) Space tower

Can we make Babel's tower that is high enough that it can use to set satellites in orbit without rockets? The fact is this.  The space tower which is the so-called lightweight version of a space elevator can be possible. The space tower is the skyscraper that reaches the low Earth orbiter or at least is so high, that it goes to edge of the space. 

The air statue inside that building keeps it in form the same way as the air statue keeps the regular skyscraper standing. So It could be possible to build a skyscraper that is high enough that it can reach the low orbiter. 

Or actually, space towers must not reach the orbiter. They can have magnetic, centrifugal, or pressure accelerators. The simplest version of that futuristic system uses the winch that pulls the rocket to the top of that tower. The regular elevator can use for that thing. 

 In some versions, the hollow tower is a roll system that moves the rocket to the top of the tower. The air statute would be between internally installed structures.

Then it can fly to the orbiter with a small rocket engine. The pressure-based version is like a giant air rifle where air pressure pushes the rocket up. And the centrifugal sling would be like a whip that gives enough speed to a rocket. That it can reach the orbiter. 

2) Space hook, also known as sky hook. 

A space hook or sky hook is a simple hook that is connected to the satellite. The only thing that the developers must remember is. The satellite must be heavier than its payload so that it can use the winch to pull the payload to the orbiter. The thing is that the space hook doesn't require that satellite be at the geostationary trajectory. The satellite can orbit quite a high altitude. 

Then the aircraft will connect the payload to the space hook, and the satellite pulls it to the orbiter. The satellite can have rocket engines for overweight situations. If that winch satellite is heavier than the aircraft it can pull the entire aircraft to orbiter. That thing can be suitable for launching things like miniature space shuttles. 

3) Geostationary space elevator, also known as equatorial space elevator.

The third system uses the centrifugal force of rotation of the Earth for sending spacecraft to outer space. The system requires an asteroid that is anchored to an extremely high tower. This is the only system that might not be able to operate. 

The tower would not face so much stress as we might think. The thing is that the asteroid or counterweight pulls the top of that structure outwards. So the weight that is targeted to the ground is not as big as it would always be. The large asteroid will just remove the weight from the system.

https://bigthink.com/the-future/space-elevator/