Today, we build an elevator into outer space. The
University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.
In 1979 Arthur C. Clarke
wrote a science-fiction book, The Fountains
of Paradise. A few months later, he wrote a
two-page letter. You can read it at the end of
Charles Sheffield's sci-fi novel, The Web
Between the Worlds.
The letter absolves Sheffield of plagiarism. You
see, Sheffield had cooked up the same mad premise
that Clarke had. Both authors proposed to replace
rocket launches with an elevator, anchored at the
equator, and reaching up beyond the level of
geosynchronous orbit. That's where an orbiting
vehicle rides directly over one point on Earth.
Clarke congratulated Sheffield for arriving at the
same idea independently.
If their idea sounds crazy, bear in mind that both
Clarke and Sheffield were distinguished scientists
who later turned to science fiction. Clarke was a
noted astronomer. Sheffield was chief scientist of
the Earth Satellite Corporation. Both used science
fiction to teach us about space travel.
And now, an elevator into space! The main element
was a cable with an extremely high tensile strength
-- strong enough to support its 22,248-mile length.
The cable was to be a single perfect crystalline
carbon or silicon fiber. We can already make
whisker-like strands of such material. And, of
course, we routinely put geosynchronous satellites
into orbit.
Above the geosynchronous level, a satellite will
fly away from earth. Below, it will fall back into
Earth. So the cable above pulls on the cable below
and holds it in place.
The cable would be tapered in thickness. It would
be thickest at the point of geosynchronous orbit,
where the stresses would also be greatest. I won't
try to recite all the technology needed to make
such a thing work. You can read Clarke and
Sheffield to see how they put such a thing in place
-- how they anchor it -- how they counterweight it
above the geosynchronous level -- how they conserve
the energy of rising and falling cars.
There's great similarity. Both authors were bound
by the same laws of physics. Both used the same
obvious name for the machine that spun the huge
single fiber. Both called it a spider.
Sheffield and Clarke's wild idea had actually been
invented independently by others before them. A
Russian engineer suggested a version he called a
"Cosmic Funicular" as early as 1960.
I certainly won't live to see such a technology.
It's too large, too complex. But some of you might.
The idea is plausible. Besides, rockets are a
clumsy, inefficient way to get free of earth. An
elevator into space is a mind-bending notion. But
it could happen. It could, one day, really happen.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
Sheffield, C., The Web Between the
Worlds. New York: Ballantine Books, 1979,
(1988 printing.)
Clarke, A. C., An Open Letter to the Bulletin of
the Science Fiction Writers of America.
ibid. pp. 245-246.
Sheffield, C., Beanstalk Update: Dynamic Beanstalks
and Indian Rope Tricks. ibid. 1988,
pp. 247-249.
Clarke, A. C., The Fountains of
Paradise. New York: Harcourt Brace
Jovanovich, 1979.
I am grateful to John Proffitt, Station Manager of
KUHF Radio Station, who pressed me for many years
to talk about this wild idea and who provided his
copy of the Sheffield book.
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
Lienhard.
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