Space Elevator

Experts agree that the biggest drain of energy takes place when a vehicle blasts off, pushing through Earth’s gravitational pull requires great amounts of fuel, but once they get out of our atmosphere, the rest is easy.

If you could cut out that “blast off” portion, space travel would be easier and much more fuel-efficient.

In a Space Elevator scenario, a Maglev vehicle would zoom up the side of an exceedingly tall structure and end up at a transfer point where they’d then board a craft to the Moon, Mars, or any other distant destination.

If it all sounds like too much science fiction, take a look at the requirements for making the Space Elevator a reality. A new material has been developed, however, called carbon nanotubes, that is 100 times as strong as steel but with only a fraction of the weight.

A carbon nanotube is an idea that makes this all sound much more achievable.

In this concept, which is very fuel efficient and which brings space tourism closer common man uses the newly added concept of nanotubes to light.

A space elevator is a proposed structure designed to transport material from a celestial body's surface into space. Many variants have been proposed and all involve travelling along a fixed structure instead of using rocket powered spacelaunch. The concept most often refers to a structure that reaches from the surface of the Earth to geostationary orbit (GSO) and a counter-mass beyond.

The concept of a space elevator dates back to 1895, when Konstantin Tsiolkovsky, proposed a compression structure, (that is, a free-standing tower), or "Tsiolkovsky tower" reaching from the surface of Earth to geostationary orbit. Most recent discussions focus on tensile structures (tethers) reaching from geostationary orbit to the ground. (A tensile structure would be held in tension between Earth and the counterweight in space, like a guitar string held taut.) Space elevators have also sometimes been referred to as beanstalks, space bridges, space lifts, space ladders, skyhooks, orbital towers, or orbital elevators.

Current (2008) technology is not capable of manufacturing practical engineering materials that are sufficiently strong and light to build an Earth based space elevator. This is because the total mass of conventional materials needed to construct such a structure would be far too great. Recent conceptualizations for a space elevator are notable in their plans to use carbon nanotube-based materials as the tensile element in the tether design, since the measured strength of microscopic carbon nanotubes appears great enough to make this theoretically possible. Current materials can produce elevators for other locations in the solar system, such as Mars, that have weaker gravity than Earth.

The US have announced interest in being the first to develop a space elevator with a potential US$10 billion project to produce the necessary carbon nanofiber and then a space elevator.

A space elevator made of a carbon nanotubes composite ribbon anchored to an offshore sea platform would stretch to a small counterweight approximately 62,000 miles (100,000 km) into space. Mechanical lifters attached to the ribbon would then climb the ribbon, carrying cargo and humans into space, at a price of only about $100 to $400 per pound ($220 to $880 per kg).

In this article, we'll take a look at how the idea of a space elevator is moving out of science fiction and into reality.

Ribbon in the Sky
To better understand the concept of a space elevator, think of the game tetherball in which a rope is attached at one end to a pole and at the other to a ball. In this analogy, the rope is the carbon nanotubes composite ribbon, the pole is the Earth and the ball is the counterweight. Now, imagine the ball is placed in perpetual spin around the pole, so fast that it keeps the rope taut. This is the general idea of the space elevator. The counterweight spins around the Earth, keeping the cable straight and allowing the robotic lifters to ride up and down the ribbon.

Under the design proposed by LiftPort, the space elevator would be approximately 62,000 miles (100,000 km) high. LiftPort is one of several companies developing plans for a space elevator or components of it. Teams from across the world are set to compete for the $400,000 first prize in the Space Elevator Games at the X Prize Cup in October 2006 in Las Cruces, New Mexico.

The centerpiece of the elevator will be the carbon nanotubes composite ribbon that is just a few centimeters wide and nearly as thin as a piece of paper. Carbon nanotubes, discovered in 1991, are what make scientists believe that the space elevator could be built. According to Dr. Bradley Edwards of the Spaceward Foundation, "Previously the material challenges were too great. But now we're getting close with the advances in creating carbon nanotubes and in building machines that can spin out the great lengths of material needed to create a ribbon that will stretch up into space"

Carbon nanotubes have the potential to be 100 times stronger than steel and are as flexible as plastic. The strength of carbon nanotubes comes from their unique structure, which resembles soccer balls. Once scientists are able to make fibers from carbon nanotubes, it will be possible to create threads that will form the ribbon for the space elevator. Previously available materials were either too weak or inflexible to form the ribbon and would have been easily broken.

"They have very high elastic modulus and their tensile strength is really high, and that all points to a material that, in theory, should make a space elevator relatively easy to build," said Tom Nugent, research director, LiftPort Group.

A ribbon could be built in two ways:

  • Long carbon nanotubes -- several meters long or longer -- would be braided into a structure resembling a rope. As of 2005, the longest nanotubes are still only a few centimeters long.
  • Shorter nanotubes could be placed in a polymer matrix. Current polymers do not bind well to carbon nanotubes, which results in the matrix being pulled away from the nanotubes when placed under tension.
Once a long ribbon of nanotubes is created, it would be wound into a spool that would be launched into orbit. When the spacecraft carrying the spool reaches a certain altitude, perhaps Low Earth Orbit, it would begin unspooling, lowering the ribbon back to Earth. At the same time, the spool would continue moving to a higher altitude. When the ribbon is lowered into Earth's atmosphere, it would be caught and then lowered and anchored to a mobile platform in the ocean.

The ribbon would serve as the tracks of a sort of railroad into space. Mechanical lifters would then be used to climb the ribbon to space.