A team made up of researchers at Shizuoka University and other institutions is set to conduct an experiment in September for a project to develop a "space elevator" connecting Earth and a space station by cable -- attracting attention as a possible dream vehicle for space travel and cargo shipments in the future.
The experiment will be the first of its kind ever to be conducted in space. However, a number of challenges, including the development of special, high-strength cables, await researchers before they can bring a cosmic elevator into reality.
In the experiment, two ultra-small cubic satellites, which were developed by Shizuoka University Faculty of Engineering, will be used. Each satellite measures 10 centimeters each side, and a roughly 10-meter-long steel cable will be employed to connect the twin satellites. The pair of satellites will be released from the International Space Station (ISS), and a container acting like an elevator car will be moved on a cable connecting the satellites using a motor. A camera attached to the satellites will record the movements of the container in space.
The microsatellites will be carried to the ISS by the H-IIB Vehicle No. 7, which is scheduled for launch from the Tanegashima Space Center in Kagoshima Prefecture on Sept. 11, alongside other small satellites. While an experiment to extend a cable in space has been conducted before, it will be the first test to move a container on a cable in outer space. If the experiment proves successful, it will serve as a step forward toward realizing cosmic elevators.
Should a space elevator ever actually be realized, people could travel to the ISS without using a launch vehicle, and transport supplies at low cost. It is envisaged that a variety of supplies -- such as panels for solar power generation and materials for research and development in space -- could also be transported to space.
Major contractor Obayashi Corp., which is taking part in the experiment as a technical adviser, is also studying a space elevator on its own. Under the firm's concept, six oval-shaped cars -- each measuring 18 meters long and 7.2 meters in diameter with a capacity of 30 people -- will constitute a space elevator. A cable connecting a platform to be set up on the sea with a space station some 36,000 kilometers in altitude will be used to move the elevator up and down using an electric motor pulley.
Researchers expect that a space elevator can speed up to 200 kilometers per hour and arrive at a space station eight days after departure from Earth. The total length of a cable to be used for the vehicle will be 96,000 kilometers, and the total cost is estimated at 10 trillion yen -- about the same as that for the maglev train project connecting Tokyo and Osaka at roughly 9 trillion yen. The cost of transport is expected to be several tens of thousands of yen per kilogram of load, about one-hundredth of that of the space shuttle.
"In theory, a space elevator is highly plausible. Space travel may become something popular in the future," said Yoji Ishikawa, 63, who leads the research team.
Various challenges await researchers, however, before they can make cosmic elevators come true, with success in the development of a high-strength cable a key factor. Such cables must be resistant to high-energy cosmic rays. Carbon nanotube is a strong candidate for materials making up the cables. Other tasks include figuring out how to transmit electricity from Earth to space, and how to avoid space debris and meteorites from colliding with space elevators.
Professor Yoshio Aoki of Nihon University College of Science and Technology, who supervises Obayashi Corp.'s space elevator project, said, "It is essential for industries, educational institutions and the government to join hands together for technological development."
(Japanese original by Ryo Yanagisawa, Business News Department)