OT: About Space Elevators - Page 2

Dragon of the void · #11 October 9th, 2002, 09:06 AM

What nobody mentioned in terms of energy used to get stuff up to orbit:

The main principle of any elevator is that whenever you send stuff UP, you send an almost identical mass DOWN (minerals mined on the moon, things produced in orbit, etc etc.). In this case you have a ridiculous small amount of energy needed for propulsion to overcome inertia ...

Just my 1 or 2 cent ... *g*

Gryphin · #12 October 9th, 2002, 12:33 PM

The down ward trip could be used to generate electricty. I belive it is called 'Dynamic Braking"

disabled · #13 October 9th, 2002, 03:07 PM

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.

Mylon · #14 October 9th, 2002, 03:13 PM

The idea behind the design is that the weight is held slightly past geosynchronus orbit so that the weight has a tendancy to fly away from the planet. The cable stops this and holds it in tension. An object climbing the cable effectively pulls the cable down, but since the cable has more inertia than the object, the elevator moves much, much more than the cable does. The tendancy of the weight holding the cable to fly away means that the weight has a constant influx of inertia to resist the tug of elevators. This inertia is probably at the cost of Earth's rotational speed, since it has to come from somewhere...

geoschmo · #15 October 9th, 2002, 03:27 PM

Quote:

Originally posted by Mylon:
This inertia is probably at the cost of Earth's rotational speed, since it has to come from somewhere...

The principles of orbital mechanics do say that you are correct, but the total mass of the cable system in relation to the earth means the amount of change in the earth's rotation will be so infinesimally small they will be practically unmeasurable. In relation to the effect of the moon and the friction of tidal effects it will be for practical purposes nonexsistant.

[ October 09, 2002, 14:30: Message edited by: geoschmo ]

geoschmo · #16 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 · #17 October 9th, 2002, 04:14 PM

So it's actually a great space kite

geoschmo · #18 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 · #19 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 · #20 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...