Space Elevators
Armstrong says space elevators must be built. He’s planning to build a carbon nanotube ribbon that is three feet wide, anchored somewhere in Ecuador, stretching a mind-numbing 62,000 miles upwards into space. The centripetal force of Earth’s rotation will keep the ribbon taut. The problem is – if I sneak on to the platform in Ecuador and snip off the ribbon at its base, what will happen?
Labels: funphysics, thinktank
posted by Rajesh Lal at
11:26 AM
13 Comments:
I would compute that if you cut the ribbion....... you'd be a lot of trouble.
Hopefully, your leg would be caught in the ribbion, and it would lift you quickly away from the scene of the crime. You soon would be flying higher and higher until eventually you'd stop rising, then you would be dragged thru the upper atmosphere behind the orbit of the upper platform.
Assuming Equador itself was not carried away into space before you got there and you have a really good scissors, the tension let loose as you cut it would probably generate a shock wave loud enough to make your ears bleed.
Because you haven't given it's length, upper platform mass, or mass per linear foot, the best I can guess is its vertical speed would be "real quick" determined by the altitude of its center of mass.
As the ribbon is now moving "upwards" on the vector defined by the Earth's center and the location at which it was detached, it would simultaneously appear to be departing Westwards over the Pacific at about 1000mph relative to your vantage point.
With everyone aghast at the noise and spectacle, you are able to sneak away unnoticed. Unfortunately, authorities have followed the trail of blood from your ears, and captured you.
As if you weren't in enough trouble, the ribbon snaps upwards and knocks off a big piece of the moon, and now everyone has to look at this misshapen satellite.
No matter, it orbits for only a few more days generating insane tides as it slowly and inexoribly crashes into Earth ending life as we know it.
This, all because you had to go playing with scissors.
Ignoring problems due to the Earth's rotation, I think nothing special would happen as the rope only requires a small (zero) force to keep it hanging at the ground.
Chris is right. Plus earths gravity is to strong for the ribbon to be effected
Chris?
Is that right?
Designs show a large counter-balance that is required to balance the load. I saw a design that would lift about 3 tons. I assumed that with no weight moving up the ribbon, the counter balance would excert a large pull upward.
But maybe I am wrong. I've never actually design one.
Ha, I see Physics Student posted while I was composing.
Finishing comment...
to be effected by the earths rotation
Hi Ragknot. I was being over theoretical.
I also am guilty of assuming that the space ribbon would not be a serious propsition if a break near the ground caused the ribbon to zoom up into the air.
I assume that there must be a tension (near the ground) a little larger than the designed payload. This in turn means that entire ribbon will have an imbalance (upwards) of a few tons. But this imbalance is acting on the whole ribbon, which probably has a total mass of thousands of tons. So if the ribbon was cut, it might rise up quite slowly.
The thing I can't work out is what shape the ribbon would be. I find it hard to believe that it would go straight up. Surely it would be "S" shaped due to the Earth's rotation.
Geosynchronous orbits are 26,199 miles. So for the elevator to remain over one location, the ribbion would have the pull the counter-balance.
It's a tug-of-war.
He's planning to build a carbon nanotube ribon 3 ft wide, and 62,000 miles long, the earths circumference is a mear 40,000 miles. The other thing to consider is how a rollercoaster works, if they weren't attached they would be thrown, the said force in the vacuum of space would have an affect on both masses direction.
As in... the earth would be pushed off its solar orbit as the fibre flew into space . The fibre could end up being in orbit of the earth.
you fools! nothing would happen as the ribbon is not anchored in the space it would simply hangs in there or come down
As usual, the fool is the one calling the others fools.
"Nothing would happen" - I don't think so! I posted a qualified version of that idea though.
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