A Moment of Science

Rope Me Up, Scotty

A geostationary satellite orbits the equator in the same direction and speed the earth turns. That means the satellite stays stationary with respect to the ground. It seems to be hanging in mid-air, if by mid-air, you mean 22,500 miles high.

Imagine yourself sitting inside a geostationary satellite. You want to bring up some supplies from earth. Why not let down a long rope? After all, your satellite will always be over the same spot of ground. Someone could stand under you, wait for the rope to come down, and tie off a cooler full of soda.

It sounds funny, but would it work? Is this just an odd way to do things or is it impossible?

In fact, it is impossible, and here’s why. When you haul something up by rope, you generally think of the object being lifted as the weight. Something we don’t consider is that the rope has to be able to lift itself too.

Lift itself!?! What does that mean?

Think of it this way. If a ten-foot rope is hanging straight down, the top one inch is supporting the weight of almost ten feet of rope. That’s no problem, but what about a hundred feet? Still no problem? How about a hundred miles?

In fact, no rope could support 22,000 miles of its own weight. Not even a cable of the mightiest steel would work. In fact, there is no material you could use that wouldn’t snap under its own weight long before it reached from earth to satellite. And that’s without even

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