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When
Science Meets Suspense
I am often asked whether certain concepts in
my books are real or pure fantasy. One of the concepts
I get the most questions about is the rotovator that
was used to lift Jake and Carin off of Earth at the
end of my book, Specific Impulse. I can assure you that
not only is that concept real, it's not even very new
or original.
The rotovator concept is a logical extension of the
idea of a space elevator, also an old idea. The concept
of the space elevator first appeared in 1895 when Russian
scientist Konstantin Tsiolkovsky was inspired by the
Eiffel Tower in Paris. Tsiolkovsky was a bit like Einstein
in that he loved to do thought experiments. He imagined
a cable with an Eiffel Tower on the top that reached
up to geostationary orbit altitude. At 35,790 kilometers,
or 22,238 miles above sea level, that would be some
tower! He noted that his "celestial castle"
at the top of the cable would be in orbit and folks
could visit by an elevator that went up and down the
cable. Simple! Problem solved – just give it to
the engineers to implement.
Unfortunately, scientists don’t often consider
the dirty little engineering problems. In this case,
Our annoying little engineering problem is that we cannot
build the cable. For a space elevator, depending on
a whole bunch of details, the cable has to hold around
100,000 pounds per square inch of tension without degrading.
Humans don't have any material that comes close to that.
Also, there's the problem of all those satellites we
already have in space. Eventually, any satellite below
geostationary orbit will hit our cable. Not optimum
at all.
So some folks began to think, "What if we turned
the problem around? What if we had a big rock in orbit
drop a line down, like a fishing line, and pull stuff
up to orbit?" This, of course, alleviates some
of the problems of the space elevator and introduces
others. For example, a fishing line which just dropped
straight down is going about 17,000 miles an hour across
the surface of the Earth. This is faster than anything
we are able to make. So we couldn't catch up to our
cable. And let’s not even mention the sonic boom
the cable would be producing.
Engineers back in the 1940’s scratched their heads
and came up with several solutions. One of them was
the rotovator. If you spin our rock in space at the
right speed in the right direction, our line would drop
straight down into the atmosphere, touch the Earth’s
surface for a while (perhaps around 30 seconds), and
go right back up again. Unfortunately, the line would
have to take much more tension than even a space elevator.
In short, we have all the technology to build a space
elevator, and for that matter, a rotovator, except for
one small piece. We still don't know how to build the
cable. But when we do… |
