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> Space Elevator, What the Hell?
FrankTrollman
post Mar 18 2008, 11:32 AM
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OK, a geosynchronous orbit has a period of 24 hours and returns to the same point above the Earth once a day. You can't leave a space elevator attached to an asteroid in geosynchronous orbit because the asteroid would move North and South in relative position and tear your space elevator to pieces. A geostationary orbit maintains the same relative position to the planet, but is also only available at the Equator. New York is not now and never has been at the Equator.

So an asteroid at the top of a space elevator wouldn't be holding it up, it would be being held in place by the cable.

Discuss.

-Frank
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DocTaotsu
post Mar 18 2008, 11:35 AM
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Erk? They put a space elevator down in New York?

I always heard that a space elevator would /have/ to be on the equator and would have to be able to oscillate so as to avoid things in space... like the moon.
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Fuchs
post Mar 18 2008, 11:38 AM
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Isn't the space elevator in equatorial africa? 2 degrees off I think.
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hermit
post Mar 18 2008, 11:50 AM
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Nope, that African installation would be the maglev space catapult ...

Poor elevator. Poor New York too. I imagine that pull from the cable will cause some tremors.

However, this is why the cunning folks at NASA would want their elevator's earth end to be on a floating platform on the equator in international waters. If you choose to adapt NASA plans, best stick to them, for they ae cunning and well thought out. (IMG:style_emoticons/default/wink.gif)
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suppenhuhn
post Mar 18 2008, 12:08 PM
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The distance a geostationary satelite has to the surface changes quite a bit, depending on the relative position of other celestial objects and the earth's wobble. Thus you'd have to construct your elevator in a way to allow for that.
Also natural geostationary objects don't exist as there are quite alot of factors that can throw you of the orbit and additionaly the possibility of a planet to catch an asteroid into a geostationary orbit is close to nil.
Ignoring this your elevator would have to support itself as, as you mentioned yourself it can't be held up by your satelite. Also it would have to be extremely rigid as to withstand the forces of the wind the shaft will experience. Even if the wind would only move it by a millimeter in the atmosphere you'll end up swinging about 70m on your satelite. Thus you'd need some kind of thrusters to allow it to float at the same position on your satelite, connecting it would most likely push the satelite off the orbit and/or break the shaft.

Crashing into the moon wouldn't be a problem though as the lunar orbit is about 10 times as far away then the geostationary orbit.
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WearzManySkins
post Mar 18 2008, 12:16 PM
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Here for all to read
space elevator Wiki

WMS
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DocTaotsu
post Mar 18 2008, 12:43 PM
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@suppenhuhn: My bust, I just remember a line from "Red Mars" that talked about how the beanstalk was so long that they had to oscillate it to avoid the moon. Evidently that isn't a problem for an Earth space elevator.
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Spike
post Mar 18 2008, 12:48 PM
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Shadowrun has a Space Elevator?

????
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Stahlseele
post Mar 18 2008, 01:03 PM
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my sentiments exactly . . what the frag ? O.o
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paws2sky
post Mar 18 2008, 01:16 PM
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Frank, You mention New York? DOe sthis have something to do with the upcoming SRM NYC arc? Or is there some RL news blurb we're missing here?
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It trolls!
post Mar 18 2008, 01:24 PM
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So New York's not on the equator, heh? Means someone has to hire Shadowrunners to alter the Earth's axis (IMG:style_emoticons/default/silly.gif)
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bibliophile20
post Mar 18 2008, 01:42 PM
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QUOTE (FrankTrollman @ Mar 18 2008, 06:32 AM) *
OK, a geosynchronous orbit has a period of 24 hours and returns to the same point above the Earth once a day. You can't leave a space elevator attached to an asteroid in geosynchronous orbit because the asteroid would move North and South in relative position and tear your space elevator to pieces. A geostationary orbit maintains the same relative position to the planet, but is also only available at the Equator.

All quite true.

QUOTE
New York is not now and never has been at the Equator.

Well, it was once... in the Devonian era. [/snarky geology student]
QUOTE
So an asteroid at the top of a space elevator wouldn't be holding it up, it would be being held in place by the cable.

Incorrect. The counterweight (the asteriod in your example) is "holding up" the cable by offering a stable location in a stable orbit (geostationary orbit) that the cable can "hang down" from. If the cable was "holding" the counterweight in place as you suggest, geostationary orbit wouldn't be needed.

It's a bit tricky to explain without delving into orbital mechanics, but, basically, the object in geostationary doesn't care if there is a cable attached to it or not; it will continue to orbit above that location on the equator until some other force comes into play. So what is done then is to drop a tether down from geosync; gravity will take hold of it and keep it taut, and due to the fact that it's anchored to something in geosync (something with enough mass and inertia to avoid being "pulled down" by the tether) allows it to basically be lowered all the way down past Low Earth Orbit and down to the ground.

That's a very rough description of the mechanics, and there a dozen other factors I could have metioned, but all of that is the very basic description of an orbitial elevator.

QUOTE (paws2sky @ Mar 18 2008, 08:16 AM) *
Frank, You mention New York? DOe sthis have something to do with the upcoming SRM NYC arc? Or is there some RL news blurb we're missing here?


Seconding the question.
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Stahlseele
post Mar 18 2008, 01:45 PM
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isn't there the problem with elevators only being able to go that high because the weight of the cable itself will be too much to be held by the cable itself? not to mention having to add a cabin and enough carry-capacity to make the idea economically viable?
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bibliophile20
post Mar 18 2008, 01:51 PM
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QUOTE (Stahlseele @ Mar 18 2008, 09:45 AM) *
isn't there the problem with elevators only being able to go that high because the weight of the cable itself will be too much to be held by the cable itself? not to mention having to add a cabin and enough carry-capacity to make the idea economically viable?

Yup. The only substance that we know of that's capable of taking the strain of supporting its own weight with enough strength left over to support cargo and/or passengers is carbon nanotubules--basically pure diamond threads.
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Stahlseele
post Mar 18 2008, 01:56 PM
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Dikote-chains O.o
else: MAGIC!
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Synner
post Mar 18 2008, 02:12 PM
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In the interest of healthy speculation, here's an FYI to bring you up to speed:

Fact: A space elevator project is underway in the Sixth World (if you missed it check Runner Havens again).
Fact: Two possible areas have been suggested as likely for the terminus - neither is remotely near NYC. (Runner Havens, again)
Fact: Several companies are retasking factories to produce buckytubes/carbon nanotubules (you guessed it, Runner Havens, but also Corporate Enclaves)
Fact: A near-earth orbit asteroid is already being moved into local orbit by a Triple A consortium. (in Emergence).

Why hasn't everyone been paying more attention to this macro engineering project? Good question. Now: discuss.
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Stahlseele
post Mar 18 2008, 02:16 PM
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when will we see the SHADOWRUN IN SPACE Core/Source/Rules-Book?
one book that deals with all the space thingies at once . . all space stations in whatever orbits, all the moon stations, and the mars stations AND this new asteroid thingie too <.< . .
rules for decompression, rules for magic in space, rules for movement and the such . . and of course, tons of fluff
how to get up/down there including the elevator . . maybe an escalator too? and rocket-ships and space-shuttles? or semi ballistic aeroplanes that go out of the athmosphere?
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paws2sky
post Mar 18 2008, 02:24 PM
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Ah ha! Okay, that makes a bit more sense...
(I don't have any of those books. (IMG:style_emoticons/default/dead.gif) )



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Dr. John Desmond
post Mar 18 2008, 02:27 PM
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It would appear after a quick glance at Runner Havens that it is an Aztechnology project underway in Panama.....
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DireRadiant
post Mar 18 2008, 02:27 PM
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The traditional beanstalk design can't be in New York. There could be a space fountain. A periodic tether hook could also work, though New York might be only one stop for that.
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Backgammon
post Mar 18 2008, 02:41 PM
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I don't know where Frank's New-York thing comes from, Synner just said nobody ever talked about New-York.. so wtf?
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Stahlseele
post Mar 18 2008, 02:47 PM
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maybe he'S talking about NY to change the fact that nobody talks about NY?
NY Rule Nr.1: you do NOT talk about NY!
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suppenhuhn
post Mar 18 2008, 03:23 PM
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QUOTE (bibliophile20 @ Mar 18 2008, 02:42 PM) *
Incorrect. The counterweight (the asteriod in your example) is "holding up" the cable by offering a stable location in a stable orbit (geostationary orbit) that the cable can "hang down" from. If the cable was "holding" the counterweight in place as you suggest, geostationary orbit wouldn't be needed.

It's a bit tricky to explain without delving into orbital mechanics, but, basically, the object in geostationary doesn't care if there is a cable attached to it or not; it will continue to orbit above that location on the equator until some other force comes into play. So what is done then is to drop a tether down from geosync; gravity will take hold of it and keep it taut, and due to the fact that it's anchored to something in geosync (something with enough mass and inertia to avoid being "pulled down" by the tether) allows it to basically be lowered all the way down past Low Earth Orbit and down to the ground.

That's a very rough description of the mechanics, and there a dozen other factors I could have metioned, but all of that is the very basic description of an orbitial elevator.


You can't put a counterweight into geostationary orbit. The moment you apply any external force towards the earth on it (like attaching a 35000km long cable) the object will start to sink and then crash onto earth as you just pulled it closer. If you want to use a counterweight it needs to be further away from the earth then that orbit so that you end up with the center of gravity of the system counterweight+tethers+climbers+payload being at a geostationary orbit or better yet a bit beyond it.

Also such an elevator isn't feasible in the least. All it does provide is a cable where your climbers can climb up on, it doesn't provide power supply or anything else. Also a single cable could only support about 20 tons of payload, maybe a bit less and thats for climber+cargo. It also wouldnt be that fast that you could have dozens of tours a day. You're way better off catapulting your cargo into space, then you also don't need to worry about how to store the energy to get there and stuff like that in addition to not have to build that thingie in the first place and maintain it later.
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GryMor
post Mar 18 2008, 03:35 PM
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There isn't ACTUALLY a requirement for the end of the tether to be at the equator, but if it isn't, you end up with some 'interesting' static structures and lose quite a bit a of lift capacity... AFAICR, you get about 50% capacity a bit north of New Orleans.

Found the slides (the old links were dead).
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cryptoknight
post Mar 18 2008, 03:35 PM
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QUOTE (DocTaotsu @ Mar 18 2008, 05:35 AM) *
Erk? They put a space elevator down in New York?

I always heard that a space elevator would /have/ to be on the equator and would have to be able to oscillate so as to avoid things in space... like the moon.



Geosynchronous Orbit is a point between the earth and moon... the station doesn't have to dodge the moon.
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