Space elevators: is science fiction about to become science fact?
With the news that Canadian space company Thoth Technology Inc. has been granted US and UK patents for a space elevator, it looks like the realms of science fiction and science fact are actually about to converge, revolutionising space travel in the process.
Reaching 20km above the planet, the proposed freestanding space tower will stand more than 20 times the height of the world’s current tallest structures, such as the Burj Khalifa in Dubai which stands at 829.8 m high, and will also be used for wind-energy generation (and we’re not talking about the nervous astronauts!), communications and tourism.
The ThothX Tower, as it has been named, will be an inflatable, pneumatically pressurised structure that is actively guided over its base, complete with an electrical elevator. Speaking about the plans, the tower’s inventor, Brendan Quine, chief technical officer, chair, and co-founder of Thoth Technology, said: “Astronauts would ascend to 20km by electrical elevator. From the top of the tower, space planes will launch in a single stage to orbit, returning to the top of the tower for refuelling and re-flight.”
Move over Charlie
The idea of taking an elevator to space is not a new one, and we’re not talking Charlie and the Great Glass Elevator here. The key concept of the space elevator first appeared in 1895 when Russian scientist Konstantin Tsiolkovsky, inspired by the Eiffel Tower in Paris, proposed a freestanding tower reaching into geostationary orbit.
Objects would attain horizontal velocity as they rode up the tower, and an object released at the tower's top would have enough horizontal velocity to remain there in geostationary orbit. Like all buildings, Tsiolkovsky's conceptual tower would be under compression. However, building a compression structure from the ground up proved an unrealistic task as there was no material in existence with enough compressive strength to support its own weight under such conditions.
Modern concepts for space elevators have focused on tensile structures or ‘tethers’, with another Russian scientist, Yuri N. Artsutanov, suggesting a more feasible proposal in 1959 of using a geostationary satellite as the base from which to deploy the structure downwards. This structure would be held in tension between the Earth and the counterweight like an upside-down plumb line.
Similar theories have followed, with American engineers Isaacs, Vine, Bradner and Bachus reinventing the concept with the ‘Sky-Hook’ in 1966, and Jerome Pearson designing a tapered cross section in 1975 that he suggested would be better suited to building the elevator. Yet, both ideas were thwarted by the lack of a suitable material in existence, or the weight of existing materials, required to construct tethers strong enough to support a tower at such height.
However, the design for the ThothX Tower gets around this problem by only building the elevator up to 20km so that it sits in the stratosphere rather than going all the way out into geostationary orbit where satellites are located, some 35,000km up.
Fountains of Paradise
It wasn’t until the 1970s that the concept of the space elevator entered the public consciousness for the first time with the simultaneous publication in 1979 of Arthur C. Clarke's novel ‘The Fountains of Paradise’, in which engineers construct a space elevator on top of a mountain peak in the fictional island country of Taprobane (loosely based on Sri Lanka), and Charles Sheffield's first novel, ‘The Web Between the Worlds’, also featuring the building of a space elevator.
Set in the 22nd century, Arthur C. Clarke’s award-winning novel describes the construction of a space elevator, a giant ‘orbital tower’ rising from the ground and linking with a satellite in geostationary orbit at the height of approximately 36,000km. In the story, Clarke’s space lift is used to raise payloads into orbit without the use of rockets, setting out the claim, in fiction, for bringing down the costs of transporting cargo by sending it directly up to satellites via a space elevator.
A lifelong proponent of space travel, Arthur C. Clarke was a renowned science fiction writer, science writer and futurist, as well as inventor, undersea explorer, and television series host. As a science writer he was both an avid populariser of space travel and a futurist of uncanny ability, and we’d like to think that the IET, or the Institution of Electrical Engineers (IEE) as it was back then, may have helped play a small part in his early writing career.
In 1949, Clarke joined the IEE as assistant editor of the journal Physics Abstracts, the forerunner of the Inspec database, a posting which Clarke himself referred to as a “brief but happy period”. By the end of World War Two a huge backlog of abstracting work had to be tackled and Clarke joined the team responsible for classifying and indexing everything published in the physical sciences.
As Clarke later said: “I probably had a bird’s-eye view of research in physics unmatched by anyone else on Earth during this period since every important journal, in every language, passed across my desk.”
Working at the IEE from 1949 to 1950, Clarke contributed the heading Astronautics to the index system, and in his spare time Clarke started his own writing, his first book commission being ‘Interplanetary Flight’, a non-fiction work on space travel published in 1950. The book was well received and is credited as being the first written in English to set out the basic technical theory of spaceflight. The book’s success led to Clarke embarking on a full-time writing career.
A new era of space travel
Historically, regions above 50km in altitude can only be reached by rocket ships, where mass is expelled at a high velocity to achieve sufficient thrust in the opposite direction. However, like Arthur C. Clarke’s assertion in ‘The Fountains of Paradise’, Brendan Quine maintains that rocketry is “extremely inefficient” and that a space elevator will take up far less energy. In the patent, the company explains that the technology offers a way to access space through reusable hardware, and will save more than 30 per cent of the fuel of a conventional rocket.
The ThothX Tower will be inflatable, made with reinforced segments and topped with a runway from which satellite payloads can be launched, staying upright by using a complex arrangements of fly-wheels to compensate for the tower bending. The elevator’s pressurised cars, or ‘climbers’, will be powered electrically or inductively, and will each carry around 10 tonnes of cargo, including spacecraft, people and equipment to a level in the atmosphere requiring less force to launch.
Traditionally, rocket ships launch vertically from Earth to about 15-25km before hitting drop-off stages when sections of the rocket drop back to Earth, usually falling into the sea. During the final stage when it enters space, the rocket is flying horizontally. As Quine explains: “In our concept, you ascend electrically [to the launch platform at the top of the tower] and remove the whole vertical launch phase. Then you get into a space plane, which is like a passenger jet, and take off horizontally.”
Quine himself cites Arthur C. Clarke’s proposal for a space elevator in ‘The Fountains of Paradise’, and indeed, the very patent for the ThothX Tower explains how a space elevator can be constructed using the cable and counterbalanced mass system.
So it looks like the evolution of an idea, begun many years ago and reinvented and re-worked along the way, weaving its way through science fiction and science fact, may yet be realised. Thoth’s president and CEO, Caroline Roberts, maintains that space travel, together with the self-landing rocket technologies being developed by other companies, will converge to bring about a new era of space transportation.