Space Elevators Faction or Fiction ?

joshcork

Wasn't too sure whether to put this in the engineering section or space but anyway.
This seems like a crazy idea but looks like this crowd called lift port have already started. They seem to be leading the practical side of the space elevator idea and after looking alittle more closely I found that there has been alot of theory talk about the subject from all over the world. Nasa seem open to the idea and might be giving a Bradley Edwards a feasability grant of a couple of million dollars. I seems like all the basic components are available to be applied other that a critical very high strengh material fot the actual elevator cable. Although these same people hope that a new technology called Corbon Nanotubes would work but are still early in manufacturing development. Rough projections show that if the materials currently being developed are as good as they are hoped that the elevator could be a reality in the next 15 to 30 years at a cost of 10 to 30 billion dollars.
Does anyone have opinons, does this idea really have merit and can it be done in our lifetime?

kurisu

you could always set up a system of tiers or something when the elevater gets to a certain height its moved to another set of cables leading to the next higher waypoint

joshcork

Well the problem with that is the mass of the cable section could not be supported with traditional materials i.e. you can't build a sykscrapper up a certain height then stop and build another next to it as the earth gravity would pull the stuff back.
So to solve this problem you need an achcor palced in geo-syncronous orbit some 100 thousand Km above the earth. This acta as counter balance so to support the weight of the elevator cable. So the key to this concept is still the very high strenght material needed for the cable itself.

Capt'n Midnight

Using commercially available materials available today you could make one for use on the moon. Weight would be about 7 tonnes for the lightest one, so 1960's technology would have got it there. http://www.universetoday.com/am/publish/lunar_space_elevator.html
http://en.wikipedia.org/wiki/Lunar_space_elevator

It could be used to drop stuff on the moon instead of having to devote 50% of the landers mass to chemical propellent.

http://www.astronautix.com/lvs/saturnv.htm
Take off weight 3,038,500 kg.
Payload: 47,000 kg. to a: Translunar trajectory. = 1.54% of take off Weight
But only 1/2 that could be landed on the moon if they used rockets to decelerate - 23.5 tonnes. (v.v.rough rule of thumb)

If they used a moonstalk then they could get 40 tonnes to the surface - ok it would be slow with a 200Kg limit on the rope at any time. but if you take it easy from LEO then it gets more interesting - LEO Payload: is 118,000 kg. if you used Ion drive, then it might be possible to get nearly 90 tonnes to the surface of the moon, nearly 4 times as much as using chemical rockets all the way.

Launch Price $: 431.00 million. in 1967 price dollars.

Lots of technical issues to sort out but the savings are considerable if it works. - You could look at a multistranded loop and constantly repair any strands damaged by micrometeroites, or adding more strands at each pass to make it stronger. At first this would be done in orbit, but later could be done on the moon too.

Figures for LEM
http://en.wikipedia.org/wiki/Apollo_Lunar_Module
Assent - 4,670 kg of which Propellant - 2,353 kg = 50.38%
Desent - 10,334 + 4,670 kg =15,004 kg Propellant - 8,165 kg = 54.4%

So of a total mass of 15,004 Kg in Lunar orbit Propellant is 10,518 Kg =70.1%
In other words a minimal possible moonstalk weighs less than the fuel used by a two man lander !

mike65

http://www.boards.ie/vbulletin/showthread.php?t=115553

Mike.