Space Elevators

By Anoushrayan Deysarkar

Speculative Science

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Megastructures are truly massive structures, which would be used for projects beyond anything we can do today. One of these is the space elevator.

A space elevator is a theoretical structure stretching from Earth to space, which allows the transport of materials and spacecraft from Earth to space and vice-versa, without the use of a rocket.

The basic idea is to have a 'tether' or cable, with one end on the Earth, and another attached to a counterweight far above the Earth. The cable - and any objects attached to it - rotate along with the rotation of the Earth, and thus experience a centrifugal force upwards. As one gets farther from the surface of the planet, the centrifugal force pulling outward along the cable rises, while the gravitational force of the Earth decreases. At a certain point - called the Geosynchronous Equatorial Orbit (GEO) - these forces balance. Above the GEO, the centrifugal force is stronger, and objects attached to the cable are pulled upward.

The counterweight will rotate faster about the Earth than the natural orbital speed for that altitude, exerting a centrifugal force on the cable and holding it aloft. Climbers would then be able to travel up-and-down the cable.

A major problem is cable strength. The material would be under immense tension along its entire length, with maximum tension at the GEO. In addition, the cable would have to be able to survive micrometeorite impacts, storms and strong winds.

For a long time, the concept was kept on the back-burner, because no known material had a sufficient specific strength to survive the tension required. Now, however, investigations have revealed that a potential process could exist for the manufacture of a material with the specific strength required.

Many ideas, such as building the elevator on top of a mountain or tall tower, have been proposed, to reduce the stress on the cable. But recently, there have been proposals for the Earth-side anchor to be a mobile platform - possibly a large oceangoing vessel or platform. This would allow the elevator to navigate around storms, high winds, and space debris, and would have the added benefit of possibly being in international waters, simplifying territorial claims.

Several plans have been put forward for the construction of a space elevator, though none have been realised yet. However, experts from the International Academy of Astronautics believe that the concept itself is feasible, and that we are closer than ever to successfully building one. Many prizes and competitions have been set up to incentivise designing a reasonable model for a space elevator.

The space elevator is a fascinating megastructure and has the potential to cut space travel costs significantly. Without the need for rockets and rocket fuel, space travel would become more comfortable, and accessible to more and more people - not just governments, organisations and the ultra-rich, but also the common people. Material and equipment transport would become easier than ever, no longer being limited by weight.

It would be a realisation of a dream humanity has long had - to climb a ladder to the stars - and it would be an important step to making the cosmos ours.