Space Elevators Face Wobble Problem

NewScientist is reporting that while the strength of the tether has long been considered the main problem in building a space elevator, a new study suggests that a dangerous wobbling problem may also be a serious obstacle. "Previous studies have noted that gravitational tugs from the Moon and Sun, as well as pressure from gusts of solar wind, would shake the tether. That could potentially make it veer into space traffic, including satellites and bits of space debris. A collision could cut the tether and wreck the space elevator."

Re:I am more concerned about the static problem

[JesseMcDonald]

Lighting rods repel lighting, not draw it.

Nope, sorry. Lightning Rods attract electrical current, thereby drawing it away from other structures that would be damaged by it.

They do both. As the storm builds up the lightning rods help to diffuse the charge. This is one reason why they have sharp ends; electrons leave a charged conductor more readily at points of higher curvature. The pathway thus created then becomes the preferred (low-resistance) route to ground in the event of an actual lightning strike.

launch loops

[nguy]

It seems to me that, at this point, launch loops [wikipedia.org] are a much more realistic and practical choice for a launch structure than space elevators.

Unlike space eleveators, launch loops require no exotic materials (just iron and steel), are essentially self-erecting, are anchored, and accelerate people quickly through the radiation belt.

We could probably build a launch loop in a decade or two, if we embarked on an Apollo-like program.

Insightful?

[dreamchaser]

How is someone who shows a total lack of understanding of basic physics 'Insightful'? As the cable gets closer to the Earth it speeds up relative to the surface. It's called conservation of angular momentum. It will indeed wrap around half the planet, though much of it will probably burn up in the atmosphere on it's way down.

Re:being unstable doesn't preclude it being usable

[clonan]

Not true....Inside the moons orbit, especially low earth orbit to geo-sync you can use reaction-less propulsion.

Specifically if you have a tether you can feed a charge onto it and it will either get pulled in or pushed out by the earths magnetic field.

This may be useful for stabilizing portions of the tether and controlling any vibrations that develop.

Re:This is awesome

[Apoorv Khatreja]

So you agree. All we have to do is install an airbag/cushion at the bottom of the elevator shaft.

Re:Then why not a space escalator?

[KDR_11k]

You hold a piece of string with a weight at the other end and you need a certain minimum angular velocity if you want to spin that around you. If you go too slow, the rope will simply wind up around you NO MATTER what material you use.

The experiment with the string requires you to keep the weight moving by pulling it with the string, a real satellite does not get pulled by a wire, it moves by its own inertia. The wire isn't what's keeping it in orbit, that's the combination of centrifugal force and gravity.