A Tether to Space
Elevators take us up buildings in a jiffy. What if they could take us to the sky?
Elevators take us up buildings in a jiffy. What if they could take us to the sky?
Ten. Nine. Eight. Strapped to your seat, you hold on for dear life. A million thoughts race through your mind. Will you make it safe? Seven. Six. An automated voice booms through the speakers, voicing out instructions to make the trip safe and uneventful. Eyes scrunched shut, you try not to look at the steel capsule you are enclosed in. Five. Four. The countdown makes it all seem twice as dangerous. You now have second thoughts about this expedition. Surely, there must be some other way. With one last prayer, you brace yourself. Three. Two. One.
As the metal box carries you upwards, your stomach does somersaults. The automated voice announces your destination. Finally, you have arrived. The capsule cracks open and you start breathing normally again. Mission successful…you enter into the third floor of your apartment.
Of course, in real life, you don’t need all this to go to the third floor; maybe to space, but to go up a few floors?
Space is considered the last frontier, but it is still quite tricky to get there. Even after more than half a century of trying, the best way we, as humanity, could conjure was to strap ourselves to a rocket full of an explosive substance and hope for the best! Returning to mother Earth can be even trickier, you may not die in a fireball, but might as well get burned to crisp re-entering the atmosphere.
There must be a better way. We travel up and down every day, fighting gravity on daily bases. And the most comfortable and safest way, at least statistically, so far is a simple elevator. Then why not scale this idea? Why not build an elevator that can take us all the way to space? A space elevator.
The idea of building some kind of structure that can get us all the way to space is an ancient one, just listen to the story of the Tower of Babel from the Book of Genesis. The entire human race wanted to make a name for themselves so badly that they decided to build a brick tower all the way to heaven. Maybe they were not aiming for space, but heaven is close enough. At least from an engineering point of view they were heading in the right direction.
Konstantin Tsiolkovsky, a little bit later in 1895, developed the concept of a tower (similar to that of the Eiffel Tower) to reach approximately 22,000 miles above the Earth’s equator, allowing a comfortable ride all the way to the void! Of course, the main limitation of such a design was its size, the structure had to support itself, and so the base of it would have to be quite an unreachable scope.
The first idea of dropping a cable from orbit and using it as a base for an elevator came in 1959 from a Russian engineer Yuri Artsutanov. This was in contrast to the idea proposed by Tsiolkovsky, and also more plausible.
A cable or tether is dropped from the geostationary orbit down to earth, and at the same time “thrown up” into space, moving its centre of mass as high as possible. The bottom of the cable is then bolted to the ground, while the top of the cable attached to a massive counterweight. All these machinations have to be done at the equator, turning the whole construction into a grand version of a merry-go-round. The planet spins, the counterweight, under upward centrifugal force, keeps the cable taut and steady. Imagine an athlete doing a hammer throw — the spinning person is the earth, the ball is the counterweight and the cable is, well, the cable. And so, from this point on we have a base for an elevator.
While it sounds exciting and fun, there are still some problems that we have to resolve. The first dilemma we face is the cable. As you might have guessed, it is the weakest link in the construction of a space elevator. It has to be an exceptionally light and strong tether, something that anybody is yet to produce.
The cable can have a variable cross section, being the thickest at the geostationary orbit, where it needs to hold up the most weight. It must support itself at a length of more than 35,786 kilometres, plus the weight of the elevator carriage, and the pull of counterweight. Any common material, like steel or aluminium, or even Kevlar, cannot handle a fraction of that.
But there are a number of lights at the end of the tunnel. There are carbon nanotubes, a super light and strong tether. It is still hard to produce in any workable length and it still does not provide required strength, but it is a move in the right direction. There are also graphite ribbons, with breaking length of around 6000km. Recently there was development in a diamond nanothread, providing another alternative for the cable material. And research is still ongoing. With new technologies, especially in nanotechnology, it is a matter of when, not if, we will get a material strong and light enough to do the job a space elevator requires.
So you might ask, is that it? Is it enough if we can research for better materials? As it turns out, there are more obstacles. After all, no one said building a space elevator would be easy!
Another problem with a space elevator concept, this time purely human created, is space debris. We managed to produce quite a large amount of space junk, which now floats on every orbit of our planet. If we stretch a cable through that area, it will have to be able to take a punch from one of those metal slugs.
One way to solve this problem is to simply have a beefy cable, but then we have another burden on the cable itself. Another way is to attach a cable to a mobile platform in the ocean instead of bolting it to land. This way it can simply dodge anything that is coming its way, and even with current technology we can easily track every piece of space debris in a given part of the orbit.
The question is, how mobile can you make the platform? It has to drag around a massive counterweight suspended somewhere in space about 100,000 kilometres away.
Lastly, an important part of a space elevator is the carriage itself, or in this case it must be a climber, as the cable will have to be stationary. The carriage will have to be able to climb up the cable, carrying the load to the required heights. Of course, it has to be powered somehow.
One way is to pass electrical current through the cable itself. Another way is to have batteries onboard of the climber, but this will eat into the carrying capacity of the carriage.
Solar power is another possible solution, and with advances in this field, it might be a viable solution in the future. And if the carriage reaches greater proportions, some form of nuclear power can be used as well.
All this said, for the climber to reach the orbit, it might take around 5–7 days if it travels with the speed of a fast train. Not super quick, but it will be a picturesque journey. With constant acceleration, it can reach the orbit much faster.
You have probably guessed one of the main advantages of the space elevator — it’s cost. Just like train tracks, it will be a huge upfront investment, but then it will be a tiny fraction to send materials into space after its construction. Way cheaper than using the current rocket technology. After constructing the first elevator, all the next ones will be much cheaper and much easier to get up and running.
Also, there is the counterweight itself. In theory it can be just a giant rock, an asteroid for example, but in practice it should be a full blow space station. With an easy way to access it from Earth, it can act as a first space colony, allowing us to conduct research, strip mine asteroids, and most importantly build structures in space, making it much easier to construct ships capable of reaching the stars in our solar system. This would render the whole space exploration endeavor much more feasible physically and economically.
Now wait a minute, this isn’t just in theory! There has actually been a lot of talk about building a working space elevator, and NASA has been looking at it for quite some time, conducting numerous researches. For example in 2000, with the help of NASA Institute of Advance Concept, scientist Bradley C. Edwards, did a full blown study on space elevators, looking into every aspect of it and coming up with tangible solutions.
But the biggest traction the idea got was in the country of giant robots — Japan. The Obayashi Corporation wants to build a working space elevator by 2050, with an estimated cost of $90 billion dollars. A rather good investment on return. With the great track record of building massive and complex structures, Japan has a good chance of being the first country to actually achieve this elusive goal.
China did throw its hat into the poll as well, upping the Obyashi claim, saying that they want to have a space elevator by 2045!
Nobody said we have to only use a cable; we can combine ideas of Konstantin Tsiolkovsky with more current interpretation to come up with some kind of a hybrid space elevator. Imagine building a super tall structure on a very tall hill close to the equator, cutting down on the required length of the cable by thousands of kilometres. Imagine stepping into an elevator (not so different from the one in Charlie and the Great Elevator) and being hurled up to the next floor — space!
You can let your imagination run wild. But if we want to conquer the stars, we need to keep on trying new ideas and on more grander scales. And we cannot get a space elevator built here on Earth; so why not try it on the Moon or Mars, where the length of the cable would not be such a problem? We just need to keep on trying.
You stand relaxed by the elevator, waiting for the doors to slide open. Just as you push the button for your desired floor, you catch your reflection on the metallic panel, and take a quick minute to flatten your messy hair! It vibrates a little; you can feel the acceleration, as the glass capsule gets pulled upwards. The elevator thrums with pleasure as it moves up, and light music floats from the hidden speakers.
Bored with the view on your side, you turn the other way. You take a look at the emergency call number, and read the instruction manual: “do not put your hand outside when the elevator is moving”, “max load: 6 persons”, and other warnings that you’ve read countless times.
Finally the elevator comes to a halt and the doors slide open with a soft whoosh. Your step is much lighter as you get out. And there you are — in the main lobby of the International Space Station!