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Need opinions and guidance building a space elevator.

#623
basscooker said:
Oh, this again. Well it's been like 5 years since I posted my thoughts. Still thinking the same way though. We aren't there yet. 2022? Nope.
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Well, we have yet to invent something strong enough that we could make large enough to build it - there are people in white lab coats out there trying, though!
 
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#624
Fat Freddy said:
Rats in space....:wideyed:
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Nahhh, not rats..... PIGS!

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#627
colcifer said:
Eventually, centrifugal force will cancel out the effect of gravity so that the structure won't have to support its own weight. Won't be done soon, though.
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I'm pretty sure centrifugal force is a fake force created to make the math work if you set the reference frame to a rotating surface. Since it doesn't actually exist, it won't do much cancelling.

For example, if you have a ball on a string and you swing it, the string would have a tension force causing the ball to accelerate toward the center (analogous to gravity). There is no outward force centrifugal force. The ball has a velocity tangential to the orbit. The force accelerates the ball to change direction, keeping it with a tangential velocity.

If you have a tower The same would happen. There isn't an upward antigravity force (centrifugal force). Furthermore, imagine the tower has a 1 degree lean in a direction. At 100 miles, the end of the tower would be a full mile away from the center of the base. I believe that would be structurally unsound. That is a lot of weight left unsupported.
 
#628
mcglyph said:
Thank for reading. To your question. There are so many...I'm mean really. I give you the first two which came to mind.
One, no more expensive, complicated, kinda dangerous rocket launches for, "routine" near earth missions. This in itself would be huge.

Second, with a very well designed, immediately useful space elevator, the very real benefits of working in a weightless environment are more quickly realized. Such things as newer stronger lighter materials perhaps.

Ok one more. In great tragic events, like the Tsunami from last year, one of the main problems is not just finding trapped people, but communicating to workers etc. Perhaps a space elevator with an infrared camera, could instantly help pinpoint victims and communicate with aid workers to save lives. No waiting for a satellite to pass by, and


Of course if you have one space elevator well then you build two, and then at some pint you start really using space, SPACE. Then one day, you have nine or ten, or fifteen, because let's face it, they are a hundred times cheaper to make and operate than one rocket launch. So now you have nine space elevators, going up, doing this or that, don't have to have anyone manning the thing, it's a robot of course, doing the things only robots can do. So now you have nine space elevators, all going up, and down doing this or that. Really exploring the moon, or perhaps enabling the population of near earth space. Imagine living in space, waking up in space, heading to the space elevator, going to work in Manhattan (a much different place in this scenario perhaps). One thing is sure though, none of this is possible without team work. And that is the most important of all! The 100000 people you mentioned. Do you know one of the many reasons the Cold War ended? The exploration of space. We realized cooperation would make things much easier in space, so this thought process while perhaps not the main reason, did certainly smooth the move a certain degree. Do you know how many countries have a space program? 50! Did you know Mexico is one? Space exploration appears to be one area where we as a civilization can work together! And let's face it, this planet needs ten times more working together. And the first step towards from earth elevators will be lunar elevators. The earth elevator unfortunately does come with MANY more problems, issues, concerns, etc. However, the lunar elevator is well within reach and will be accomplished in less than ten years.
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Is the lunar elevator an elevator from earth to the moon?
 
#630
James Collins said:
I'm pretty sure centrifugal force is a fake force created to make the math work if you set the reference frame to a rotating surface. Since it doesn't actually exist, it won't do much cancelling.

For example, if you have a ball on a string and you swing it, the string would have a tension force causing the ball to accelerate toward the center (analogous to gravity). There is no outward force centrifugal force. The ball has a velocity tangential to the orbit. The force accelerates the ball to change direction, keeping it with a tangential velocity.

If you have a tower The same would happen. There isn't an upward antigravity force (centrifugal force). Furthermore, imagine the tower has a 1 degree lean in a direction. At 100 miles, the end of the tower would be a full mile away from the center of the base. I believe that would be structurally unsound. That is a lot of weight left unsupported.
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Sadly not everyone pays attention in highschool.
 
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#631
ZenG said:
That thing is going to swing in the breeze.

You'll be rocking back and forth in 800ft. arcs up top.
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Assuming it was just built and perfectly straight for an instant, I think it would swing one time, and crash into the earth. Assuming, it is 1 ton per 10 feet of building that would be 11,088,000 tons of material crashing into the earth. If this fell and half the structure hit Earth at 250 miles per hour, that would be 7 Megatonnes of TNT worth of energy. By comparison, the bombs at Nagasaki and Hiroshima were 0.035 Megatonnes combined.

I will keep my dollar.
 
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#634
Did anybody mention this problem? A space elevator, if built, would sweep through every point in space up to 22,500 miles. This means eventually every bit of space junk in orbit will strike it. Not a negligible problem.
 
#635
James Collins said:
Assuming it was just built and perfectly straight for an instant, I think it would swing one time, and crash into the earth. Assuming, it is 1 ton per 10 feet of building that would be 11,088,000 tons of material crashing into the earth. If this fell and half the structure hit Earth at 250 miles per hour, that would be 7 Megatonnes of TNT worth of energy. By comparison, the bombs at Nagasaki and Hiroshima were 0.035 Megatonnes combined.

I will keep my dollar.
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In theory a space elevator might weight anything between 20 and 750 tons.

Assuming worst case scenario:

Velocity at Geo = 3.07 km/s.

(kinetic energy of 750 tons at 3.07 km/s) = 3.206×10^12 J (joules)

Which is about 95% of the maximum fuel energy of an Airbus A330-300 (97,530 liters of Jet A-1) or 1/20 of a little boy bomb.

The potential energy of 750 tons falling from 35000km is larger but still only in the range of .05 megatons and most of that would be lost to friction with the atmosphere.

Imagine spreading .05 megatons of TNT along a line 20,000 km long (still erring on the side of "more disaster"), that gives you 2.5 tons of TNT per km or put another way, 2.5 kg of TNT per meter.

Imagine a stick of dynamite about 5.6 cm's thick that's 20,000 km long. That's the total energy of the falling space elevator.

You wouldn't actually want that hitting you but if you were 50 yards away from the line you'd probably be fine. Again, that's even pretending no loss of energy to the atmosphere as it falls.

A falling space elevator wouldn't be great but more along the lines of "it's bad to be hit by things falling on you" rather than "everyone nearby is very dead"
 

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