SciTech

How Things Work: Space elevators

Dreams of space flight and deep space exploration have always been present in the
human mind. With the advent of modern technology, a simple and reliable method to
send people and objects into space seems to be increasingly feasible. Many methods have
been proposed, but the actual implementation of any of them still poses a major challenge
to today’s researchers and scientists.

One of the leading ideas suggested so far is the space elevator, which has the purpose
of transporting goods from the surface of the Earth to space. The concept is not new;
it was first proposed by Konstantin Tsiolkovsky as a tall tower that would reach into
space, with a large “castle” at the top of the tower. However, in 1895, there was no technology suitable to build such a tower. Today, the possibility of building a space
elevator is greater with advanced materials.

The modern version of the space elevator would be an extremely long, thin carbon
nanotubule ribbon that would extend around 100,000 kilometers. Carbon nanotubules
are structures composed of carbon atoms that are bonded in a hexagonal pattern,
which can be rolled in a cylinder. This allows for immense strength and other unique
properties. Currently, scientists are working with both single-walled and multi-walled
carbon nanotubules, which describe a carbon nanotubule as one with a single rolled
layer or one with multiple rolled layers.

Carbon nanotubules are the material of choice for space elevators because of their strength. A recently tested version of a carbon nanotubule had a tensile strength of 63 gigapascals, capable of supporting 6300 kilograms with a surface area of 1 square millimeter. When its density is taken into account, it has a specifi c strength nearly 312 times more than high-carbon steel. In addition, many different forms of carbon nanotubules are yet to be tested, and some have predicted tensile strengths almost three
times higher than the strongest known versions today.

Most designs of space elevators involve a base attached to the Earth, a cable, an elevator,
and a counterweight. Bases can be attached to ocean vessels, allowing the space
elevator to maneuver to avoid storms, debris in space, and other obstructions. They can
also be attached to the tops of towers or mountains, which would decrease maneuverability
but increase availability to power supplies and reduce the overall thickness,
and weight, of the cable.

The cable would be composed of carbon nanotubules, which would increase in thickness
as the cable increased in height. However, with modern technology and costs of
production, linking carbon nanotubules sturdily is not feasible. As cheaper and more
reliable and effective methods of connecting carbon nanotubules are discovered, the
costs of production would decrease, and space elevators will become more of a reality.

A space elevator would not be complete without the elevator, which has been proposed
to only climb upward using rollers, and essentially fall back to Earth at the top.

As the elevator ascends, it would increase its velocity, keeping a geosynchronous velocity
as its height increases. Solar and nuclear energy have been considered to power the
climb, but weight of the equipment for these kinds of energy is an issue. Researchers have
considered using laser beams to power the elevators, or even another cable to conduct
electricity.

The applications of space elevators would be numerous. Once an object is at the top of
a space elevator, its velocity would be great enough to escape the gravitational pull of
earth. Space flight and space exploration would benefit, as well as those with a commercial
space interest.

While space elevators are well-known, many other designs have been suggested to
put objects into space. Lightcraft are vehicles that use the power from lasers to propel
themselves upward. The laser would shine on the bottom of the vehicle, which would
generate enormous amounts of heat at that spot. This would heat air surrounding this
region and produce and upward thrust.

Launch loops are tracks that would use electromagnetism to accelerate an object into, or past, Earth’s orbit. The design is similar to the tracks used by maglev trains, which also use electromagnets for acceleration. Space guns have also been considered, which would shoot objects into space. However, this would require an extremely high velocity and would subject the object to tremendous forces, which would not allow humans to travel on space gun projectiles. Placing a space gun in a high elevation would reduce the amount of force needed to propel an object, but the object itself would still need to be able to correct
its velocity to stay in orbit.

Space flight is a relatively new event in human history, and technology is continually advancing to catch up with our ideas. Space elevators, and many aspects of space exploration, are only theoretical today, but in the future, they will likely become
a reality.