TOKYO -- The idea of building an elevator to space may sound like the stuff of science fiction, but thanks to Japanese developers, the dream may become a reality as early as the middle of this century.
A team led by Nihon University professor Yoshio Aoki has developed the basic technology for an elevator system that moves along cables that extend far up into the sky -- as high as 1.2km in experiments. The system could find applications in space tourism and for transporting large quantities of materials skyward.
The Japan Space Elevator Association, an incorporated entity that aims to develop and popularize the concept, hosted a competition in August to test different elevator systems in Fujinomiya, Shizuoka Prefecture. The event evaluated the performances of devices from 17 teams as they made their way up and down a cable hanging from a large balloon.
Aoki's team from Nihon University used a device roughly the size of a golf bag and which weighed 11.6kg. It climbed at a speed of about 20kph, ultimately ascending to an altitude of 1.2km. The machine descended at an average clip of 40kph, but its motor was damaged along the way. The winning team's device did not make it quite as high as Aoki's, peaking at 1.1km, but its movements were more stable and it was not damaged during its journey.
Dreaming bigger, higher
Nihon University's prototype is designed to carry loads of up to about 3kg, but the team plans to double that for next year's battle and reach an altitude of 2km. For that to happen, the drive device and tires will have to be improved. "We will also design it to move more efficiently, minimizing the effects of wind and vibrations," Aoki said.
Aoki and his crew aim to achieve altitudes of 15km and payloads of 100kg by 2020. Experts estimate that space elevators will be considered practical when they are capable of carrying 20 tons to an altitude of 50km. Aoki has set 2030 as his target for making that a reality.
The cables envisioned for space elevators are some 96,000km long -- one-quarter of the distance from the earth to the moon -- have a thickness of 1.4mm and a width of 18-48mm. To ensure stable operation that does not damage the cables, it will be necessary to have a setup that automatically controls the position where the cables are gripped and mitigates the effects of any vibrations. Also, there is thought of using solar cells and ground-based lasers to power the elevator.
Space elevators would offer a less costly, safer transport alternative to rockets, where explosions are always a danger. They would also make it possible for people to travel to space without having to undergo extensive training. Such a breakthrough would open the door to new opportunities in the areas of resources and energy, as well as in space tourism.
Numerous challenges remain, however.
According to plans for a space-elevator concept unveiled in February 2012 by general contractor Obayashi, if construction were started on a facility to anchor cables to the ground in 2025, the project would be completed in 2050. Construction would cost around 10 trillion yen ($97.6 billion).
The cables would be made of carbon nanotubes, which are 20 times stronger than steel. The envisioned elevator device would ferry payloads between the earth and a space station at speeds of 200kph.
Although Nihon University and other organizations are making solid progress on the basic research, the long-fiber nanotubes needed for the cables have yet to be developed. Moreover, the mass production needed to bring down the costs of such cables does not yet exist. Even the question of the overall safety of making a trip to space by elevator remains unanswered.
The hardware will have to be strong enough to handle whatever Mother Nature throws at it. Also, there is the danger of collisions with space junk, to say nothing of meteorites. Beyond the many technological hurdles is the issue of securing the massive funding necessary to pay for such an undertaking.