Today, a story about four hairlike jets and an
iceberg. 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.
If I say the word iceberg,
the image of the Titanic probably
enters your mind. That ghostly mountain of ice,
looming out of the fog to gash your hull, is part
of our collective unconscious. It almost seems we
were there -- that we shared the terror of that
unhappy night in 1912.
Now recall a terror that hasn't visited you yet,
but one that will someday -- sooner or later. You
man an offshore oil rig somewhere in the Northern
seas. Out of the gloom drifts an iceberg. This time
you are stationary. The ice moves toward you --
very slowly -- maybe one mile an hour. And you have
no way to elude it. At first it's more beautiful
than terrifying. Then you measure its size. It can
weigh 20 million tons -- fifty times more than any
ship on the sea. It moves like vapor, but it could
crush you like an egg. And it's just as dangerous
in bright sunlight as it is in night fog. What can
you do?
Somehow, it has to be towed off its path. But how
do you grasp an iceberg? Tie a rope around it?
Throw a net over it? The trouble is, icebergs
aren't stable. They roll over. Figuring out how to
grasp a mountain of ice, so a ship can tow it away,
is a lot harder than it sounds.
Engineers in the state of Washington have invented
a way to anchor a towrope in an iceberg. The tow
ship drops an odd little submarine into the water.
It sidles up to the frozen mountain, just a few
feet below the surface. Holding itself in place
with water jets, it drills into the ice. But
drilling a clean hole in ice isn't easy. They do it
with four tiny jets of water, just over a hundredth
of an inch in diameter. They issue from tiny
sapphire nozzles at 1300 miles an hour -- twice the
speed of sound.
The jets work together to hollow out a long,
four-inch hole in the ice. Into the hole goes a
steel anchor for the tow cable. Liquid carbon
dioxide cements the anchor in place by freezing
water around it. It makes a powerful adhesive. The
first trials have been successful. It seems likely
that tow ships will be able to exert a 50-ton pull
on an iceberg. That's enough to move a really big
one off course at 1/7th of a mile per hour.
What a strange study in contrasts all this is.
Sapphire and ice! We create a delicate ocean ballet
-- danced by elephants moving with the speed of
snails. The key to grasping a block of ice, 20
times bigger than the Great Pyramid, is a set of
four jets, not much bigger than the hairs of your
head. As the magnitude of our technology grows it
creates strange problems. And it answers them with
even stranger solutions.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
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