A Line to the Moon

[insane_alien]

yeah, i know. but you calculated the force the earth is supplying to keep the moon in orbit. the force the chain has to withstand will be a LOT less than that.

 

i'll go see if i can find an example to explain it.

 

okay, i can't find the place i was thinking about so i'll have a go myself. We'll use a 'traditional' space elevator instead of one to the moon to keep it simpler.

 

okay. contrary to intuition, the greatest forces woldn't be at the ends but the middle. more precicely, geostationary orbit altitude. the force at the earth station could be zero in theory but would probably have some arbitrary force for tension and control purposes. this is because the cable is in orbit. a geostationary orbit. the cable below this altitude is dangling from the part at this altitude and the part above is moving faster than orbital velocity so trying to fly outwards. a counterweight like a small asteroid is likely to be used to reduce the length of the cable above. the end on the counter weight will be providing some centripetal force but not ALL of it like you were calculating for the moon.

 

the force at the counter weight would be the force required to lift the entire cable minus the bits above geostationary and a bit more for orbital effects. it would not be the force of gravity between the asteroid and the earth. i hope you get it.

 

another point of veiw is that if you did attach a chain to the moon that provided that force then the moon would start to accelerate towards earth. it's in equilibrium now and you're talking about doubling the force acting on the moon. thats a big force. the time it spends accelerating towards the earth would depend on the cable elasticity but it would definitely throw its orbit out of whack.

[MolotovCocktail]

Makes sense, but I'm pretty sure you would still need a chain that can withstand an astronomical amount of force on it before it can start to change the orbit of the moon. Certainly not as much as I calculated, but a lot still.

[insane_alien]

yes it would take a lot of force to significantly change to orbit of the moon. and you calculated a force that big. thats the force holding the moon in place right now. doubling it would severely alter that orbit.