Small - Nanotechnology—with its ability to write pages
of information on the point of a pin—has NASA scientists
thinking small. Really small. (5/10/01)
Me To The Moon - With advances in flight technology, the idea
of anyone—not just trained astronauts—going beyond
earthâ€™s limits doesnâ€™t seem so farfetched anymore.
Elsewhere on the web
elevator takes off - BBC
& Outrageous: Space Elevators - NASA
Elevator: Next Stop, Earth Orbit - Space.com
d'Ailleurs/House of Elsewhere - Museum of Science Fiction,
Adventures, Ltd. - "end of year specials available now"
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.â€™ 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
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.