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NASA just landed a second rover on Mars. President Bush wants to send people there, too. He's called for new technology to make space travel easier. As this ScienCentral News video reports, nanotechnology might lead the way, by making possible an elevator into space.
Going Up?
An elevator into space has been a feature of science fiction for more than a hundred years. In 1895, Russian scientist and author Konstantin Tsiolkovsky looked at the elevators heading up the Eiffel Tower and imagined a "celestial castle" tied to Earth. Most notably, in his 1978 novel The Fountains of Paradise, Sir Arthur C. Clarke wrote about engineers constructing a space elevator on top of a mountain peak on an equatorial island.
Now physicist Bradley C. Edwards, research director at the Institute for Scientific Research, Inc., envisions a space elevator based in the Pacific Ocean and rising to a satellite in geosynchronous orbit.To take the space elevator, also known as a geosynchronous orbital tether, from science fiction to science fact, scientists would need a very strong, flexible cable long enough to reach from our planet to a satellite. Edwards thinks that nanotechnology could make that cable—and the space elevator—reality. "You can build it in the near future," he says, "and the reason is because of the new carbon nanotubes that are coming out and being produced commercially."
A carbon nanotube image: Rice University
Carbon nanotubes are rolls of sheets of graphite, the same substance in pencils. "If there was one material that I would hold up and say 'This is it' as far as nanotechnology is concerned, that is carbon nanotubes," says Pulickel M. Ajayan, professor of materials engineering at Rensselaer Polytechnic Institute. Discovered in 1991, these tiny structures are light and flexible, yet one hundred times stronger than steel. But they're very hard to control. "We know the structure of nanotubes," says Ajayan, "but the question is, can we really put them together in the way we want?"
In the past year, nanotechnologists around the world have made progress. At Tshingua University in Beijing, China, and the University of Texas at Dallas, researchers have developed various methods of spinning long fibers out of carbon nanotubes. At the Second International Conference on the Space Elevator in September 2003, Rodney Andrews of the University of Kentucky's Advanced Carbon Materials Center presented a photograph of a spool of nanotube-fiber just over three miles long.
But a space elevator would need a cable at least 66,000 miles long—and it would have to be very strong. Dr. Ajayan points out that to be useful, these new fibers, which usually combine carbon nanotubes with other materials, must retain nanotubes' singular strength.
Most recently, chemical engineer Matteo Pasquali and his research team at Rice University found that by combining carbon nanotubes with sulphuric acid, they could align them in the same direction – which he says would help retain their strength. "If you drop a handful of chop sticks onto a table," Pasquali explains, "they scatter all over and take up a lot of space. When you pack them into a box, they have to line up side by side, pointing in the same direction, in order to take up much less space. If carbon nanotubes are lined up in a fiber, the properties would be best."
NASA and the Department of Defense may start exploring ways to build a space elevator, but there's still a lot of work to be done before anyone can press "Up" into space.
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