# chain to the moon?

I’ve always wondered, would it be somehow physically possible to have an extremely long chain, or a rope or something that could link the earth with the moon. If such a chain was strong enough, and you pulled hard enough, could the moon be thrown out of orbit. Also, if you had a hose or a pipe in place of said chain, would atmosphere “leak out” into space? I realize the impracticality of this scenario, but I’ve always wondered if it could physically BE done.

Talk amongst yourselves.

Thanx

Chris W

Anything like that would most likely melt or burn up in the Earth’s atmosphere, not to mention gravitational pull.

Why does this remind me of the person who asked what would happen if all the people in China jumped off chairs at the same time?

<looks out window to check for a full moon>

The chain would be rather heavy, remember it’s about a quarter of a million miles to the moon. If somehow there were enough energy to put a chain there, it would immediately snap under its own weight, falling in heaps on the moon and earth.

A hose would not let the atmosphere leak out. Gravity is the only thing holding the atmosphere in place now and the hose would not change that. Think of the atmosphere as an ocean of air, the difference being that the surface is not quite as distinct.

And welcome to SDMB

I just pictured that, the chain snaps and starts falling faster and faster in a pile until it starts melting from the air friction. It would likely snap at the point of neutral gravity between earth and moon so you’d have somewhere in the neighborhood of 200,000 miles of chain falling. It’s virtually impossible but if someone managed it I’d be there with my instamatic.

Since the earth is rotating, the chain would wrap around it, causing the moon to come closer and closer till it crashes on the earth!

However, such a chain is impossible to make, at least with our current technology. Even the best synthetic fiber would snap under its own weight. The concept of a space elevator is popular in science fiction, and somewhat easier. What you do is start with a space station in geosynchronous orbit, and extend a pair of rails or tubes, one down and the other up. If extended all the way down to the earth, you can use that shaft to run an elevator. Rockets become obsolete. I’m not sure if there are materials strong enough to do this - certainly nothing we can produce in industrial quantities though.

As for the leaking of the atmosphere, the ‘ocean of air’ analogy is a good one. If you stick a straw in your soda can, does the soda squird out the top of the straw? No, because gravity holds it down, same as elsewhere in the can.

One problem among many: the moon isn’t in a stationary orbit. The idea of a tethered satellite in stationary orbit (sometimes called an “orbital tower” or “space elevator”) has been explored. For SF treatment, see “The Fountains of Paradise” by Arthur C. Clarke.

You would have to account for the fact that not only does the Moon orbit the Earth, both rotate at very different rates.

If one were to imagine a fixed cable somewhere at the equator on earth, infinitely strong, once the two were connected the earth would begin to spin up the cable at approximately 1100 mph, 29,000 miles a day, like a giant yo-yo. At the same time, the moon would describe a sort of spiral into Earth’s gravity well. Within about a week, BOOM! Don’t bother to plan for Granny’s ninetieth.

To prevent this, one might build enormous semicircular arcs anchored at the poles–frictionless, of course–and attach the cable or chain from the arcs. From space, it would appear as if two desk-globes were sitting out there. Then one need only worry about the eliptic orbit of the moon. But hey, if you have infinitely strong cable and frictionless axles, that’s not much of a problem at all.

…and if you attached some blades to the axle in Antartica, and added a Caspian-sea sized portion of blueberry syrup, humans would have an eternal supply of Slurpees. That, I think, is a good thing.

What yabob said…

If you do read it look up some of the references in the Bibliography. Very interesting

What they all said.

scr4 - I don’t think there’s any material that has been conceived of that even approaches the needed strength.

SofaKing - Bwahahahahahahaha!!!

Riserius1, are you perhaps familiar with the phrase “wired to the moon” used to refer to a person whose mind works in, shall we say, rather eccentric ways?

Popular Science did an article about 2 years ago about a carbon fiber chain made of buckyballs thats tensile strength was high enough that it would never break under it’s own weight.

–Tim

…even if you lowered it towards a place with higher gravity than Earth, like Jupiter or a black hole?

I think you need to consider a few things on this chain.

First) A very very small percentage of the rope is actually being affected in any significant way by gravitational pull. Sure, there’s always SOME pull, but when you consider the rope is 250,000 miles long and you leave our atmosphere after around 100 miles, most of that rope is just sort of floating there.

1. The moon can’t be pulled out of orbit by us. It would merely change orbits. If we really pulled hard enough, here’s what would probably happen: The moon would come crashing down on us as we rose up to meet it. Somewhere around 1/4 of the distance to the moon, we’d meet and BOOM! We’d go bouncing back and forth like two superballs on a string. Eventually things would settle down (sans life on this planet), and we’d continue orbiting the sun like always. The orbit there would be sort of strange, considering we’d be spinning kinda like those two spaceships on that old Space Duel game.

2. Atmosphere is kept in place naturally. You can’t stick a straw into it and expect our air to be sucked out like it was Mega-Maid in Spaceballs. If that were true, then any space debris coming into the atmosphere, and any ships leaving it, would create huge holes on top that continually sucked air out. If you want to kill us all, I like the moon crashing better anyway.

3. Nothing will burn in the atmosphere just floating there and if ,for some reason, it came loose from the moon I can’t guarantee it would fall back towards us anyway considering that 99.9% of its mass is outside Earth’s atmosphere to begin with

5)Assuming it does though…hoo boy would that be fun. Basically, anything that size would need to be, at the very least, a mile in thickness to support itself. It would wrap around the earth ten times before coming to a rest, creating tidal waves, earthquakes, and complete and total oblivion wherever it landed. My kinda party.

Ummmm… what’s so special about the buckyball configuration re strength. You’re describing a product of near infinite strength. It’s ultimately carbon atoms in a chain after all and (I would imagine) have some tensile breaking limit within normal limits even if it was extra strong.

It seems like someone’s been playing Sonic CD

In Star Wars novels, they make references to “skyhooks”, semi-space stations that have a “tether” that can be connected to the planet below. The tether contains a turbolift (very fast elevator). I imagine that the tether contains anti-gravity mechanisms to provide support against the gravitational pull.

I know that’s not exactly a “factual” answer, but the point is that we needn’t necessarily rely on orthodox construction techniques to make “space elevators”.

This was an old Pogo routine, before the moon landing. Howland Owl determined that the way to get to the moon before the Russians was to shoot, out of a cannon, a rocket with a thread attached. Attached to the thread would be a string, attached to the string a rope, attached to the rope would be a heavier rope; then Albert could climb up to the moon, hand over hand.

And Albert would keep the Russians off the moon, by waiting until the moon was down to a thin crescent, then he would lure the Russians down to the edge and just push them off.

At this point, Albert suggests they should review the plan in case something should go wrong, and Owl says, “Why review the plan? What could possibly go wrong?”

There’s an important fact which no one mentioned yet. Namely, that the moon always has the same side facing Earth. This mean that one end of the chain could be anchored to center of that face, and would rise straight up from the surface of the moon, and continue until friction with Earth’s rotating atmosphere presents a problem. This could be significantly lower than a geosynchronous orbit, I believe.

Yes, tensile strength would still be a problem.

Only because its rotational period and the Earth’s have become synchronized. Please don’t think that the Moon doesn’t rotate. It does, once every 24 hours, which is why you see the same face all the time.

Methinks you are a wee bit confused, or your humor is too subtle for me.