OT: About Space Elevators

geoschmo · #1 October 9th, 2002, 03:35 PM

Quote:

Originally posted by Hadrian Tyrael S. Aventine:
My concern is what if they can't move it away from the hurricane in time.

A project like that is going to be measured in the hundreds of trillions price tag and with gov't buying, they'll make 2 and 3x the price.

I also think they will come up with a self-clibing mechanism to pull stuff up. Sure it's slower, but we can slap an italian sticker on it and say it's romantic.

The estimates on the website are in the tens of billions actually. The main hurdle is designing the ribbon itself. Once that is done and the system is up and running, it could very easily pay for itself in a short time.

Well the ground unit can be placed in areas of historically low storm activity. And it can be moved to an extent, if the ground station is a mobile one. I would imagine that in the event of a particularly nasty storm, the cable could simply be disconnected and "Reeled up" out of danger. The ground station would just need to batten down and ride it out then.

Geoschmo

Urendi Maleldil · #2 October 9th, 2002, 04:14 PM

So it's actually a great space kite

geoschmo · #3 October 9th, 2002, 04:21 PM

Quote:

Originally posted by Urendi Maleldil:
So it's actually a great space kite

Right, so all we have to watch out for are great space kite eating trees.

Baron Munchausen · #4 October 9th, 2002, 05:14 PM

I don't think wind is a concern. The cable will be far stronger than any material we currently know. Disturbance of the anchor point is more of a concern. If the wind increases the stress on the anchor point then maybe it would be a problem. Very rough seas if it's a platform at sea, or earthquakes if it's on land, could damage the anchorage and break the link.

That's an interesting thought on 'reeling up' the cable to avoid ground problems. If the system is well balanced I suppose it would be possible to detach from the ground point for periods of time. It would be easier to do this if there was an 'intermediate' station only a few hundred miles up. A seperate cable from this station to the ground would be easier to 'reel up' than a portion of the whole 22,000 mile cable. The 'convenience' of going straight to geosynch orbit would be lost but maybe the other convenience from this multi-stage arrangement would be worth the change. Most uses would be for near-earth orbit at first anyway. Once you got into true orbit there would be plenty of leeway for fancy arrangements of cables and stations.

Now I'm having visions of a system of a web of giant cables all around the earth and cable cars running between all points like subways in a large city today. Come to think of it, if you have multiple geosynch stations linked by a 'perimeter' of cables you'd be released from the necessaity of the ground link. They'd hold each other in orbit. Hundreds of thousands of miles of cable would be required for this, though.

Just don't let a huge system like that get out of synch with the earth!

[ October 09, 2002, 16:17: Message edited by: Baron Munchausen ]

dogscoff · #5 October 9th, 2002, 05:58 PM

Quote:

around the earth and cable cars running between all points like subways in a large city today.

So I could buy myself a �50 ticket and scoot up a cable off the coast of Australia at 9am. Then I could zing around the Earth on a super-fast space cable car and scoot back down another cable in the North Sea in time for lunch the same day. (except that it would be midnight... yeesh, jet lag would be horrendous.)

Then I could spend 19 hours and �200 trying to get from one end of Britain to the other by train...

geoschmo · #6 October 9th, 2002, 06:11 PM

The purpose of the ground link isn't to keep the ribbon taut. The ribbon doesn't have to be rigid, just basically stationary. You can't let it move around too much or you get problems with harmonic vibrations on the line. That would cause wild gyrations in certain spots that could damage the cable and/or cause the climbers problems. Anyone see the video of "Galloping Girdy", the bridge that tore itself apart in the wind. That wasn't because of a tremendous wind, it was just a slightly more windy than normal day, but the frequency of the vibrations in the bridge tore itself apart. That's the concern with the wind for the space elevator. That sort of thing can be actively dampened for the ribbon, but that requires manipulation at the ends. So they have to be attached to base stations. That is the danger of wind.

I don't know if they have any plans to reel up the cable in emergency situations like this, but there is no reason why you couldn't do it all the way from the high orbit. An intermediary station would be an unnceccesary complication. You don't have to take up the entire length of the ribbon, jsut reel up 15 miles or whatever to get the bottom end above the weather. The only quetions would be the reel having sufficent torque to take up the mass of the entire length of the cable. But the reel will have to be able to handle the mass of the entire length of the cable anyway or you would never be able to get it down to the ground in the first place. The only way to set the elevator up is to launch the spool in the conventional way and then reel it down from orbit.

Geoschmo

Suicide Junkie · #7 October 9th, 2002, 06:37 PM

Quote:

So I could buy myself a �50 ticket and scoot up a cable off the coast of Australia at 9am. Then I could zing around the Earth on a super-fast space cable car and scoot back down another cable in the North Sea in time for lunch the same day. (except that it would be midnight... yeesh, jet lag would be horrendous.)

You could also send packages from Tokyo at 8:00am, and they would arrive at the pacific coast of america by 5:00pm the previous day!