Magnetically levitated space elevator to low-earth orbit (2001) [pdf]

Post by dekhn » Sat, Aug 03, 2024, 9:07 PM UTC

ben_w wrote: post #74

dekhn wrote: post #49

Earlier quoted context omitted.

Trillions+ in mining value? What exactly are you proposing mining (platinum seems the most likely, IIRC my D&D)? remember that new sources affect the supply, which changes prices significantly, so it would have to be basically unobtanium to be worth it. And remember, since you developed all that tech just to make the space elevator... most of the mining you did is probably obsolete.

Even aluminium gets you to a trillion dollars in 6 years. https://en.wikipedia.org/wiki/List_of_countries_by_aluminium... * Calculation: http://www.wolframalpha.com/input/?i=1%20trillion%20USD%20%2... * Old data, China has rapid growth in this sector and is now about 42 megatons/y, but that just changes the result from rounding down to 6 years to rounding up to 6 years: https://www.reuters.com/markets/commodities/chi…

Post by dredmorbius » Sun, Aug 04, 2024, 3:41 AM UTC

hinkley wrote: post #93

dredmorbius wrote: post #85

Earlier quoted context omitted.

The one thing that's clear is that this makes tethers a more challenging engineering problem than a naive / uninformed view might have suggested. This is almost always the situation in engineering applications. The simple approach based on first principles turns out to be massively influenced by second- and higher-order effects. See Admiral Hyman Rickover's "Paper Reactors" for a classic take on this: https://whatisn…

Reminds me of a futurist I read years ago who was sure super critical water oxidation would solve all of our pollution problems. Ceramics are a “Pick two” material. You can handle heat, pressure or corrosion. SCWO requires all three. Some clever team invented composite ceramics trying to fix the problem, but that was a decade or two ago and still it’s a niche solution used for truly pernicious toxins and that’s about…

Post by spacebacon » Sun, Aug 04, 2024, 10:56 AM UTC

ben_w wrote: post #88

spacebacon wrote: post #86

Earlier quoted context omitted.

Current maximum continuous length is about a foot.

At present. From context, I infer the question is "we know what we can use 1cm long carbon nanotubes for, and what we can use 36,000 km long carbon nanotubes for, but what economic value is there for stuff between such that we may try to monetise the R&D pathway to the latter?"

Post by chmod775 » Thu, Aug 08, 2024, 12:57 AM UTC

seanhunter wrote: post #96

chmod775 wrote: post #87

Earlier quoted context omitted.

Even an optimal space elevator needs to support a sizable portion of its own tether weight with the tether itself. For a solid non-magnetic tether to be at all realistic, the tether material would likely be so light relative to it's length/volume, it'll never be at all dangerous regardless of how high you drop it from - its terminal velocity would be tiny. I can drop some yarn, fishing line, whatever, from whichever…

But I thought the whole point of an elevator is you elevate things. Which means the line falling wouldn't be the biggest problem- that would be the payload falling to earth surely?

Post by simne » Thu, Aug 08, 2024, 11:34 PM UTC

richk449 wrote: post #56

dekhn wrote: post #43

There's a simple point about space elevators that most people ignore. We would only build a space elevator if it made economic sense. Given the reality of construction costs, even if we had the materials, it would like cost many trillions of dollars (at least) so whatever we used it for would have to produce much more value than that. Even more importantly, if we had access to the materials necessary to build space e…

Many technologies are developed long before they are viable because they have military value. Access to space is currently a major national security issue, so a space elevator could be a manhattan project. Some technologies are developed by the free market before they are economically viable too. LEO constellations for instance (both the original - iridium, and starlink).