Project of the century: why we need a space elevator

“Take a piece of twine and tie a stone to it. Start spinning this primitive slingshot. Under the influence of centrifugal force, the stone will pull the rope tight.

And what will happen if we fix such a “rope” at the Earth’s equator, stretch it far into space and hang the appropriate load on it? Calculations show that if the cable is long enough, the centrifugal force will stretch it in the same way as a stone stretches our twine preventing the load from falling to Earth. After all, the Earth’s gravitational force decreases in proportion to the square of the distance, and the centrifugal force increases with increasing distance. And as high as an altitude of approximately 42 thousand kilometers, the centrifugal force will be equal to the force of gravity. This is how long should be our “rope” to the Cosmos: fifty, or even sixty thousand kilometers! And a quite considerable “load” must be suspended from it, because the centrifugal force must balance the weight of the rope almost 40 thousand kilometers long! But if this is done, there will be a direct cableway from Earth into Space!”.
Space elevator (computer simulation). Source: Glenn Clovis

This was a quote from an article published in 1960 by engineer Yuriy Artsutanov. It went down in history as one of the first works where the concept of a space elevator was discussed in detail — a hypothetical structure capable of completely revolutionizing the entire space industry, radically simplifying the delivery of cargo into orbit and reducing its cost.

Of course, the space elevator is only a theoretical concept. Its practical implementation is hindered by both engineering challenges and the lack of a global need to create such a structure. But this should not prevent us from discussing this idea and thinking about what benefits it could bring to humanity.

How to build a space elevator

So, to create a direct path into space, we need to somehow bring a super-strong cable to a point above geostationary orbit, and then somehow balance it. Or, on the contrary, build a space station up there and find a way to drop he cable down to the Earth’s surface.

Scheme of the space elevator

Next, we equip the cable with a lifted intended for the transportation of goods and passengers. Voila — the space elevator is ready. The force of the Earth’s rotation will accelerate the cargo capsule allowing the payload to be launched directly into orbit.

In words, everything seems simple. But, of course, in practice, everything is much more complicated. Creating a road to space requires extraordinary engineering solutions and technological breakthroughs. Without them, the space elevator will remain a beautiful fantasy.

The key challenge for designers is the creation of a cable that can withstand enormous loads and at the same time not “collapse” under its own weight. Having gone over all conceivable options, the engineers came to the conclusion that carbon nanotubes are almost the only material suitable for making such a rope. In fact, the strength of any nanotube obtained in the laboratory has not yet reached the values that would allow them to be used to create such a structure. In addition, it is also necessary to figure out how to weave them into a cable thousands of kilometers long. It is not surprising that many experts are quite skeptical about this idea itself believing we will never be able to get a material with the necessary characteristics. For example, the famous Elon Musk stated in an interview that, in his opinion, it is much easier to build a bridge between Los Angeles and Tokyo than to build an elevator to orbit. At the same time, the entrepreneur expressed hope that he was wrong in his assessment.
The structure of a carbon nanotube

However, not so long ago, a promising alternative appeared among carbon nanotubes. Experiments conducted by American scientists in 2014 showed that super-thin diamond threads can have even greater strength. However, this is still just a theory. Only new research and experiments will answer the question of whether such threads can claim the status of building material for a space elevator.

Let’s suppose that engineers really manage to create a super-strong cable tens of thousands of kilometers long. Even in this case, they will have to solve many other tasks. Another important issue is the location of the elevator’s base. Obviously, it should be on the equator. At first glance, a ground site seems to be the best option. It greatly simplifies the construction of the accompanying infrastructure and access to the elevator, and also makes it possible to slightly reduce the length of the cable.

But, of course, you can’t just build the base of the elevator on the best part of the equator. First, a thorough assessment of all potential risk factors (tectonic stability of the region, probability of floods and other natural disasters) that could threaten the integrity of the structure is necessary. Secondly, the political aspect must be taken into account.

The construction of the space elevator requires obtaining the permission of the national government to use its territory for the “project of the century” and firm guarantees of the complex’s security. Perhaps the closest historical analogies are Suez and the Panama Canals. They were grandiose engineering projects for their time. Their successful implementation had a huge impact on the entire world economy. However, in practice despite all the “eternal” agreements, both of them eventually became hostages of international conflicts and were used as levers of pressure to achieve certain political and economic goals. In the case of the Suez Canal, the matters even degraded down to warfare.

An alternative to the ground platform can be a marine platform located outside the territorial waters of any particular state. This will exclude problems related to its jurisdiction. Another advantage is the potential ability of the offshore platform to maneuver, which will give it the opportunity to evade threatening hurricanes and storms. But, of course, this option will be more difficult and expensive to implement than a ground site.
The floating base of the space elevator can also serve as a base for oceanic research. Source: Wikipedia

The next important question for designers to answer is the choice of a counterweight that will balance the space elevator. There are two main ways to solve this problem. First, you can use some heavy object like a space station or a captured asteroid as a counterweight, to which the end of the rope will be attached.

An interesting alternative to this option is the use a second cable as a counterweight (or a prolongation of the already existing one), directed further on from the Earth. It will straighten and stretch under the action of centrifugal force. The described option is advantageous due to the fact that the load moving along the second cable, will accelerate to high speeds comparable to the escape velocity from the Earth. This will make it possible to use it as a catapult to launch a payload into interplanetary space. Of course, such a decision is pregnant with further increase in the cost of the project, but it will significantly boost the overall efficiency of the elevator, making it a tool for exploring not only Earth orbit, but also deep space.

It should be borne in mind that although the elevator will radically simplify access to space, in order to construct it, mankind will have to launch a large number of different cargoes into orbit. And that involves a lot of traditional launches with all the attendant problems.

It will also be necessary to somehow solve the problem of protecting the structure from collisions with satellites that are still functioning and fragments of space debris. It is necessary to figure out how to save the passengers of the elevator in the event of an accident and protect them from radiation when crossing the Van Allen belts. And, of course, an important part of the system should be a reliable mechanism that will allow the cabin to be lifted without damaging the cables. The list of such challenges goes on and on.

We have discussed only the general concept of a space elevator. Over the past half century, many different modifications of its basic scheme have been developed. But they are all based on the same physical principles, and their implementation will require solving similar engineering problems.

Why do we need a space elevator?

Let’s assume that humanity will cope with all the problems listed above and get the opportunity to build a space elevator. But why do we need such a titanic structure?

Yes, from the economic point of view, a space elevator can really radically reduce the cost of bringing cargo into space. Various calculations show that it will be measured in tens, at most, hundreds of dollars per kilogram of payload. This is many times less than modern rockets on chemical fuel. So, it would seem, the benefit is obvious.

But one should not forget that the construction of an elevator implies huge financial investments. Now it is impossible to estimate them even approximately. It is only obvious that these amounts can be compared with the budgets of the world’s leading states.

Therefore, the space elevator will be able to pay off only in the case of its active use, which involves the daily launch of a large amount of cargo into orbit. Currently, humanity, of course, does not have such a need. But it may well arise in the foreseeable future.

We may need a reliable and cheap route to space for full-scale colonization and terraforming of Mars. Such a project requires sending a huge amount of various equipment and millions of settlers to the Red Planet. Even Elon Musk’s Starship is unlikely to be able to cope with such a workload. The space elevator will actually open the Solar System to mankind. Thanks to it, bases on the Moon and Lagrange points, Martian colonies and flying cities on Venus will become a reality.

Another potential task that may require the construction of such a structure is to help save the Earth. We are already seeing the first evidence of how climate change caused by anthropogenic activity is affecting our planet. The situation may worsen significantly in the future. Some experts warn that the point of no return has already been passed and even an immediate reduction of harmful emissions into the atmosphere will not improve the situation. Therefore, “external” aid projects are already being developed. One of them involves the creation of giant space mirrors that will reflect part of the sunlight falling on the Earth’s surface. This will allow it to cool the planet down, reducing the effects of global warming. We can also mention the projects of orbital solar power plants, which will help eliminate our dependence on the burning of fossil fuels. The presence of a space elevator will facilitate the construction of such megastructures.

Finally, the space elevator is able to help us reach the stars. As you know, the star system closest to us is separated from the Sun by trillions of kilometers of space. There are several projects of ships that would be able to withstand such a long flight and fulfill the centuries-old dream of mankind. But all of them require the presence of a powerful orbital infrastructure, which will allow to build a starship, whose mass will be measured in many thousands of tons, provide it with everything necessary and send it on a grand journey. Without a space elevator, it will be incredibly difficult for humanity to realize this task.

All of the above tasks can hardly be solved by a single superpower or even a group of several countries. They will require the resources of all humanity. So, we can safely say that the space elevator is a tool of a global scale. It is not just a grandiose structure, but also a kind of symbol. Its construction will mean the transition of Earth’s nations to the phase of maturing, readiness to act together, be responsible for the fate of the planet and move on as a single whole.

Of course, now all this seems fantastic, but we should keep in mind that once upon a time the idea of creating channels connecting different oceans or a manned orbital station was fantastic. Now we treat them as something natural and absolutely trivial. So it can be assumed that our nearest descendants will witness the beginning of the construction of the “highway into space”.