Space Elevator (The Epic Tower) (Page 16)

Zereous Excentris
Zereous Excentris: I guess I am right about Gravity having a roll to play in wind changes.. hmmm.. but.. who cares about me gitting something right.. OMFG though boy do they cry when I make mistakes!
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CorwinCorwin (Wireclub Moderator)
Corwin: Huh?

You suggested that the tidal pull of the Moon causes wind changes... this is not correct.
Although there is such a thing as "atmospheric tides", the effect that the Moon's gravitational pull has on the atmosphere as the Earth rotates every 24 hours is barely measurable, and is more pronounced in the upper rarefied atmospheric layers.
This tiny effect is insignificant, especially in comparison the how much the heat of the Sun affects the atmosphere every 24 hours.
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@ Aura - Yes, the stratosphere does rotate slightly slower than the atmosphere at lower altitudes which match the rotation of the Earth. But as the atmosphere is very thin at those high altitudes, I don't think it will have too much of an impact on our hypothetical 36,000km tall skyscraper.
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Zereous Excentris
Zereous Excentris: if that atmosphere shifts to gravity.. and pulls with the moon you think that does not effect wind.. thats absurd to beleive that all of the atmosphere being pulled like the tide does not effect wind.. because it effects jet current under water..
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CorwinCorwin (Wireclub Moderator)
Corwin: The lunar tides have a much more pronounced effect on the oceans, due to the fact that ocean density does not change with depth, whereas the air density changes drastically with altitude.
And as I said, it's only the upper rarefied atmospheric layers that are measurably affected... this effect is translated into a minuscule increase in heat...
... an increase that is a THOUSAND times smaller than how much the Sun heats the atmosphere in 24 hour cycles.

The lunar atmospheric tides have such a tiny impact on the atmosphere that it's hardly worth mentioning.
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Zereous Excentris
Zereous Excentris: Woow.. It is still a damn effect.. I am sure shit would get fucked up with the atmosphere without the moon effecting it.. Especialy the water equating into it aswell. seeing as it rises the water and lowers it.. ALSO effecting the Atmosphere Genius!
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Aura_
Aura_: Cor, can I just point out that meteors mostly start 'burning' in the mesosphere, which is above the stratosphere and thinner still, yet thick enough to heat those ice rocks to form streaks of light. Yes, I know, speed helps a lot in that. But I wasn't saying the heat generated by the tower would set it aglow, I just said there would be enough heat to create a problem. Along with static charge which builds up.
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CorwinCorwin (Wireclub Moderator)
Corwin: Meteors are typically traveling at over 10 times the speed of a spacecraft on reentry - about 70kms/second on average. Whatever air currents would buffet our imaginary space-tower shouldn't be much of a problem regarding friction.

Now, electric current, on the other hand, would be tremendous... but not because of friction or static charge, but rather because of the current that exists within the magnetic lines of the Earth's magnetic field, and charged by the solar wind. A 36,000km tall tower would set up a tremendous amount of current.. but the tower would be grounded, so the current would flow down to the Earth. If anything, this current could be harnessed and utilized as a bonus freebie power source, as long as we could properly conduct it downwards. (a room temperature superconductor would be helpful).

Some years back, the Space Shuttle tried a "tether" experiment, and sent out a probe attached to the shuttle with about 2 km of wire... as a result of the above mentioned current, the thing ZAPPED and vaporized the tether... not a very useful experiment.
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CorwinCorwin (Wireclub Moderator)
Corwin: Aura's mention of the "centrifugal pull" concept reminded me of Arther C. Clarke' idea of how a space-elevator could work:

A giant space-station (or spacecraft) with a cable lowered down and attached to the ground, and an elevator platform that rode the cable up and down... he used this idea in his sci-fi novel The Songs of Distant Earth... I found this idea preposterous, although not as preposterous as a 36,000km tall skyscraper (Clarke used the space-skyscraper idea in his sci-fi novel 3001: A Final Odyssey).

Okay... the cable idea... in theory, yes, this is imaginable:
The space-station would orbit geosynchronously, but at a higher altitude with a greater than orbital velocity to achieve tension on the cable as a result of centrifugal force.

The space-station would need to be very massive... massive enough to counter the weight of the cable, plus countering the full-weight at ground level of the largest mass you would want to lift.
Now the cable itself will "weigh" much less than it's mass... at 36,000km the cable matter weighs 0% of it's mass, and at ground level the cable matter weighs 100% of it's mass under one G. The weight of the cable material decreases with altitude in proportion to [a] it's centrifugal velocity, and [b] the weakening gravitational pull in regards to the distance squared... to calculate the overall weight of the cable requires Calculus (dammit) that is beyond my abilities (and an internet search was of NO help at all)...
... so let's just say that the cable will weigh "a fraction" of it's mass, and move on.

The "tension" required of the cable, and the extra distance and extra-orbital velocity needed of the massive space-station will be a matter of "how much" mass you want to lift from ground-level. Although the mass will lighten increasingly as it rises, it will put it's full weight on the cable as it first rises... so... how much mass we can burden this cable with depends on how much tension we can put on it... in other words - how frickin' STRONG is this hypothetical cable we're talking about?? And how thick would it need to be? (It's thickness will also determine how massive the cable will be, adding to the needed tension factor to support the weight of the cable itself).

Now, as I mentioned, I'm no good at Calculus, but I believe Mr. Clarke came up with some rough figures... and this 36,000km (plus) "cable" would need to be constructed out of a material with three very special properties:
[1] Lightweight
[2] Be almost indestructible with super-tensile strength
[3] Have superconductive properties

In regards to weight, if it's strength-to-weight factor isn't great enough, the thickness of the cable to achieve the required tension keeps increasing... the thicker the cable the more heavy it is, and the more tension you need to put on it, etc, etc,... a curve that approaches infinity... or in other words, if it's not light and strong enough this entire endeavor is impossible. I seem to remember that Clarke's imaginary cable was about as light as aluminium and about 10cm in diameter.
In regards to superconductivity... as I mentioned before, a cable that long will pass through the highly charged electromagnetic lines of the Earth's magnetic field and Van Allen Radiation Belts, setting up a current of perhaps billions of watts. Any electrical resistance whatsoever would fry that cable into vapour in a millisecond, so nothing less than superconductivity would be required... and I don't see how super-cooling tens of thousands of kms of cable would be possible, so we need "room-temperature" superconductivity.

So... no problem... we just invent some magical new metal or material that's lightweight, almost indestructible with super-tensile strength, and is a room temperature superconductor...
... no problem.

This all went through my head when I first heard Clarke describe his space elevator idea, and why I found the idea preposterous. This is easy to do in a Science Fiction novel; you just say the material exists, and Bob's your uncle... but then why not just say that anti-gravity generators exist, or Warp Drive, or Superluminal Interplanetary Teleportation?

I know, I know... because Clarke's idea works with just ONE bit of new technology... simply an indestructible superlight superstrong superconductor material.
To be honest, I think if we could develop a material like that, we could also develop awesome new spacecraft that have no trouble lifting into orbit from the ground... why muck about with space-elevators or mega-skyscrapers?
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Aura_
Aura_: "why muck about with space-elevators or mega-skyscrapers?"
Traffic congestion? It's not about getting them from the ground into orbit only, it's getting them from orbit to the ground as well.
They main difference though, it that we consider Warp drive and teleporters mathematically and physically impossible. The elevator is merely unlikely.
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CorwinCorwin (Wireclub Moderator)
Corwin: Good point, Aura.

Our present method of "air-braking" with reentry is very damaging to any craft we intend to use over again. The space shuttle ended up being a very bad idea in the long run. The newest "workhorse" command-module/reentry vehicle that NASA has in the works, named Orion, is based on the "single-use" Apollo craft, historically their most reliable design ever, although sadly disposable.

But if we had some kind of new and amazing form of propulsion, that didn't require such a bulky fuel source like our primitive chemical rockets, we could use the engines to slow the craft down BEFORE we entered the atmosphere... then just glide down like a conventional aircraft without the heat of reentry.

The concept of Fusion propulsion was tossed around in Sci-Fi novels as far back as the 1950s from writers like Asimov and Heinlein... but we haven't gone very far in that direction, and even Deuterium isn't the most compact fuel imaginable.

The REAL pie-in-the-sky fuel would be Anti-matter... our present understanding of physics knows of no more a powerful reaction than that. I once read that an amount of Anti-matter the size of a shirt-button would unleash the equivalent power they used to put a Saturn V rocket into space.
But I imagine that mucking about with Anti-matter would be a very dangerous endeavor... a sizable enough amount of anti-matter to propel a craft to relativistic speeds would also likely be enough to vaporize the planet. We'd do well to do that kind of experimenting our around the orbit of Neptune.

A quote from Arther C. Clarke -- "Some of the supernova we observe may possibly be industrial accidents."
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Zereous Excentris
Zereous Excentris: Imagine this Construct made out of an asteroid.. Using mirror to bounce light into a central complex orbiting the Star of sol.. Using light to Forge asteroids from the asteroid belt into seamless Bladed sword ships!
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CorwinCorwin (Wireclub Moderator)
Corwin: You kind of lost me on this one, Zereon.
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Zereous Excentris
Zereous Excentris: Its a Star foundry! pumping out epic Sword Bladed star ships! Using light to heat up Iron.. from the asteroid belt.. and.. carbon and aluminum and some silica is added to the iron to make carbon spring steel..
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