Up, up and away
The United States space agency, Nasa, has described the idea of building a space lift as 'audacious and outrageous'.
Such infrastructure reminds one of the fairytale Jack and the Beanstalk, in which some magic beans sprout a monster beanstalk that soars into the sky.
The concept of a structure reaching into space dates back to 1895. Russian rocket scientist Konstantin Tsiolkovsky was inspired by the Eiffel Tower in Paris to conceive of a free-standing structure that reaches from the surface of the Earth to a geostationary orbit, at an altitude of 35,790km above sea level. A 'celestial castle' would be at the top of the proposed tower. From that platform, objects could be launched into orbit without using a rocket.
The idea evolved under the guidance of many scientists and engineers, until 1979, when the concept was spread to a wider audience by the simultaneous publication of novels by science-fiction authors Arthur C. Clarke and Charles Sheffield.
In Clarke's The Fountains of Paradise, engineers build a space lift on top of a mountain in the fictional country of Taprobane. The author, who died in March last year, predicted a space lift would be built 'about 10 years after everyone stops laughing' and would make space shuttles obsolete.
Sheffield's The Web Between the Worlds envisages a load-bearing cable, or 'beanstalk', stretching from Earth to a geostationary orbit.
In March 2005, Nasa and US-based non-profit organisation the Spaceward Foundation, which promotes space science and technology education, announced they would foster the development of space-lift-related technologies through competitions under the 'Elevator: 2010' banner. Two challenges under this initiative form what is now known as the annual Space Elevator Games. They are focused on two concepts that will enhance Nasa's space programme - power beaming, for wireless power transfer, and nano-materials, such as carbon nanotubes, for strong tether structures. The most difficult task for participants is developing a tether material.
Creating the technologies are vital if a version of the space lift proposed in 1960 by Russian engineer Yuri Artsutanov and enhanced in 2000 by US physicist Bradley Edwards is to be realised. Their system involves the construction of a stationary cable rotating in unison with the Earth, with one end anchored on the planet and the other in space. Electric cars would travel up and down the cable, carrying cargo and people. According to Ted Semon, a retired software engineer and author of The Space Elevator Blog (www.spaceelevatorblog.com), the twin influences of centrifugal force and gravity would keep a 100,000km cable taut.
Brian Turner, team captain of the KC Space Pirates, a Space Elevator Games competitor from Kansas City, in the United States, says the practical problems in developing the cable are enormous. 'Although there are many details that may not work out, the primary roadblock is that there are no materials strong and light enough to make the needed cable,' he says.
What's needed is an ultra-flexible material about 200 times tougher than steel, hence the need for carbon nanotubes, a new class of materials setting the scientific community abuzz.
The Spaceward Foundation estimates the start of construction of a space lift, with all the relevant technologies in place, could fall somewhere between 2020 and 2025.
Once completed, it would have a price tag of less than US$10 billion - a lot cheaper than programmes such as the space shuttle.