The first challenge is finding something in space to attach the cable to. The solution is using satellites in geostationary orbit.
A regular traction elevator works by using a strong cable to move the elevator cabin up and down between the floors in a building through ‘traction’ which means ‘pulling’ or ‘lifting’. There is a weight attached to the other end of the cable that helps balance things out. This makes it easier to move the cabin smoothly, without using too much effort. In that sense, it is much like a seesaw that works better when similar weights are placed on both sides.
You get into the cabin and press a button. An electric motor then pulls you up to the floor you want. As the cabin moves up, a counterweight moves down. When the cabin goes down, the counterweight goes up. This system helps the elevator run smoothly and use less power.
A space elevator works along similar lines, but on a much bigger scale. Instead of just going up a building, it uses a very long cable that stretches all the way from space down to Earth—covering thousands of metres. And, instead of using a rocket to reach space, one can simply travel up a cable in a cabin to space. This method uses much less energy than a rocket and does not create any pollution.
It may sound unbelievable, but people have actually been toying with this idea for a long time. Surprisingly, the concept goes all the way back to 1895, when a Russian rocket scientist and one of the early thinkers in space travel, Konstantin Tsiolkovsky, came up with the idea of a ‘sky ladder’.
Satellites to Attach Cable
The first challenge is finding something in space to attach the cable to. The solution is using satellites in geostationary orbit. This is a special area in space where satellites stay fixed over one spot on Earth because they move at the same speed as Earth’s rotation. That way, they always stay above the same place. This orbit is about 36,000 kilometres (22,200 miles) above the Equator, making it a good spot to anchor the cable.
A very long cable needs to be dropped from a satellite down to Earth. As the rope gets longer, the satellite can move slightly higher to stay balanced and not get pulled down since the very weight of the rope, itself, pulling towards Earth could drag the satellite out of position. To keep the rope steady and stop it from swinging or swaying too much, a heavy weight could be attached to the other end of the rope, far out in space—in other words, on the side opposite Earth above the satellite in space. This helps keep everything in place and well-balanced.
The cable has to be secured to the ground with a strong anchor. Some experts think it may be better to place this anchor on top of a mountain or a tall tower. This way, the cable would not have to be as long, making the whole setup slightly less cumbersome.
Ship or a floating platform
Newer ideas suggest using a moving base, such as a ship, or a floating platform, out into the ocean. This base could be placed in international waters and be moved around, if needed—for instance, to stay away from storms or falling space parts if anything goes wrong above.
Now, imagine we have a space elevator. It uses a machine called a ‘climber’ to carry things up the cable into space. But does lifting such heavy stuff not risk dragging the whole elevator back down to Earth? Experts say that is not a problem. Their calculations show the elevator can safely carry a load that is up to 1% of the cable’s weight. Since the cable will, possibly, weigh hundreds of tons, it can still lift a pretty good weight without any trouble.
There is still a big challenge with the cable. It has to be about 50 times stronger than steel! Scientists have been working for years to create a material strong enough, but, so far, no one has been able to make it work.
A recent report from the International Academy of Astronautics mentions that such materials as carbon nanotubes, or graphene may be strong enough for a space elevator cable. Experts who spoke to the BBC believe this technology could become a reality within the next few years. It is certainly something to keep an eye on!
(The author Girish Linganna of this articles is an acclaimed, award-winning science writer who brings science and nature to life with clear, everyday language)
Topics
