You've heard of wishing on a star. NASA looks up at the stars and wishes for an elevator that we could ride into space instead of big, expensive rockets.

As this ScienCentral News video reports, a farsighted few dream that an incredibly tiny, uniquely strong structure could make the space elevator real.

Press One for the Moon, Two for Mars

The notion of a space elevator was born in 1895, when a prolific Russian scientist and author, Konstanin Tsiolkovsky was inspired by the Eiffel Tower in Paris. Since then, the space elevator has resurfaced periodically in scientific journals and science fiction, most notably in Arthur C. Clarke's 1978 novel, The Fountains of Paradise.

Both NASA and the U.S. Air Force have mulled over the space elevator. In 2000, NASA Marshall Space Flight Center published the proceedings of a workshop on space-elevator design. The key question is how to build a cable capable of stretching from earth to space. Right now, no known material has the requisite strength and flexibility.

Three years ago, physicist Brad Edwards realized that proposals for the space elevator always envisioned "a very, very grand system, consistent with someone saying 120 years ago, 'I'm going to build a Boeing 747.’ A large system just isn't possible. However, we can cut it down to a mall system, which is viable with current technology." Edwards suggested that a yard-wide, paper thin, unbreakable ribbon cable could be constructed from a fiberglass-like composite, made with nanotechnology's major discovery to date: carbon nanotubes.

A carbon nanotube is a rolled-up sheet of graphite, a form of carbon that is very familiar to most people from broken pencils. However, at nanoscale, in the form of a single sheet, graphite is one of the strongest known substances, because the bonds among its atoms of carbon are so strong.

Carbon nanotubes were discovered in 1991 by Dr. Sumio Iijima's research group at NEC Corporation in Tokyo. These minute structures combine enormous strength with low weight and flexibility, making them ideal materials for use in space.

At the time of the discovery, Dr. Pulickel Ajayan was working with Dr. Iijima. Today Ajayan is a leading nanotubes researcher at Rensselaer Polytechnic Institute in Troy, N.Y. He has succeeded in creating strands of linked nanotubes, but only a few inches in length.

Dr. Ajayan is not optimistic about any space elevator offering rides in the near future. Despite nanotubes' exceptional properties, their very perfectness makes them difficult to control—even after more than a decade of research. At atomic level, their surfaces are almost entirely smooth, and that makes them very hard to use to construct anything. Dr. Ajayan says that even composites combining a polymer and nanotubes are a challenge because nanotubes are so hard to control: "It's not as simple as throwing carbon nanotubes into a polymer and getting the best out of it."

Meanwhile, Edwards remains unshakably optimistic. A former NASA official has put him in touch with engineer Robert Shambaugh at the University of Oklahoma, who is making composites from polyprophylene reinforced with carbon nanotubes.