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While I have no doubt it would require an unreasonable amount of material and resources, so not doable... I wonder.... would a space-elevator made out of modern materials, but shapped like a pyramid with a broad base, be able to be made tall enough to extend into space. I figure if the base is wide enough and the materials at least as strong as solid rock, it should be possible... but without running the numbers I dunno... I do know there is a limit on the maximum size of a mountain so .... i dunno.
Internet has no answers.
@freemo tl;dr – I don't have anything intelligent to add about maximum heights using rock or other modern material...
How high would it have to be? 100km to "space", but what application does a 100km space elevator have?
I found something saying that 10 miles is the max mountain height, but I think that was taking into account how fast mountain growth processes are vs. erosion, so I don't think it applies to this project: we can probably go quite a bit higher.
I agree it seems like if you go wide enough the rocks can probably support 100km without basically liquefying and squishing outward? I think? But I think the crust will deform a ridiculous amount, so be sure to take that into account. :)
> How high would it have to be? 100km to "space", but what application does a 100km space elevator have?
130 miles to be at the lower end of LEO and service the ISS.
1.2k miles to be at the top of LEO and service all things in LEO..
I'd say that since it facilitates easily bringing fuel to space putting it at the lower end is fine since now there is enough fuel for them to get to a higher orbit anyway.
> I found something saying that 10 miles is the max mountain height, but I think that was taking into account how fast mountain growth processes are vs. erosion, so I don't think it applies to this project: we can probably go quite a bit higher.
Yea its hard to say how this might translate over to a man made structure though, thats the problem.
> I agree it seems like if you go wide enough the rocks can probably support 100km without basically liquefying and squishing outward? I think? But I think the crust will deform a ridiculous amount, so be sure to take that into account. :)
Yea it is both these effects im not sure about... I know if you dig even 1 mile down the pressures are so high that the walls of your tunney will slowly move like a liquid and close in unless you reinforce them... go too much deeper and even reinforcement doesnt work.
The depest we ever dug was 7.6 miles.. but im not sure if the limiting factor has any relationship to this...
@freemo "130 miles to be at the lower end of LEO and service the ISS." But it's whizzing by at 5 miles/sec; most of the work is just getting up to speed, isn't it?
I guess the higher up you go the better, (less air etc?), but unless your elevator is quite a bit higher than these numbers you don't really get the main savings of a space elevator.
@freemo I think the expensive part is getting enough horizontal speed. Taking off at LEO-heights, you avoid air and the need to gain potential energy. This is like a fifth of the fuel or something. But sure: not nothing.
@ech I was thinking more in terms of something already in orbit being able to pick up supplies from the elevator, including fuel, and then taking that to a higher orbit or escape velocity.
But now that i think of it your right, the thing would be moving so fast past the space elevator it wouldnt have time to pick up the items, and even if it had some sort of hook or something the speed would just not be managable...
That said if it could somehow pick up the supplies it could work, it would just have to pick the up the fuel then immediately use it to speed up as it would get slowed down by trying to pick it up.
@ech Do you though? The point of a space elevator is to save you fuel.
avoiding the most fuel expensive part (getting out of the atmosphere where drag is significant) seems it would be a huge save, especially since now you can pump fuel to that point and not need to lift it there via rocket.