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Under the most advanced design of the SE, what are the values of the (tensile) strength and other qualities of the materials needed? What are those of the best materials we have in our hands now?

longtry
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    The header question is largely answered here https://space.stackexchange.com/q/2/26356 and https://space.stackexchange.com/a/4629/26356 see also https://en.wikipedia.org/wiki/Space_elevator#Cable_materials. Short answer is that we can make make millimeter shards of material that approach the required properties, but would need a flawless thousand km lengths to build a space elevator. – GremlinWranger Apr 09 '23 at 06:51
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    We need not only a very strong but lightweight material, we also need a huge space transport capacity to be able to build an elevator. We need to solve the problem of the space debris in orbit endangering the elevator. We need a method to assemble or produce the elevator cable in orbit. So we are not close but very far from a space elevator. – Uwe Apr 09 '23 at 06:56
  • @GremlinWranger Thanks. So carbon nanotubes, at 100 GPa, are really close to the hypothetical threshold of 130. This gives me real hopes! I thought that our current materials are orders of magnitude insufficient for the task, not 77% already. As humans are ever-ingenious, I believe we'll fill the gap (and more) in the future. – longtry Apr 09 '23 at 09:45
  • @Uwe The initial space transport capacity could be solved with rockets, I think. I do have an idea about the debris. But assembling the SE is admittedly a big, big problem. Unless humanity unites, that future might be indeed far. – longtry Apr 09 '23 at 09:48
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    @longtry Space Elevators on earth are something that can only happen with global agreement, since it heavily restricts satellites below GEO due collision risk and worst case failures include 'killing a measurable % of earths population'. Recommend a browse of https://space.stackexchange.com/questions/tagged/space-elevator – GremlinWranger Apr 09 '23 at 10:23
  • The initial space transport capacity would be done with rockets, we got nothing else. To build an elevator we need to transport a huge mass for the cable. So the elevator should lift much more than this huge mass within its lifetime to be economic. But how the elevator is disassembled after it's lifetime? How is the cable repaired or replaced if necessary? – Uwe Apr 09 '23 at 11:30
  • @GremlinWranger "heavily restricts satellites below GEO" But does it though? Even if we were to give the elevator a generous "keep out" zone, orbital satellite flyover density is lowest at the equator and it shouldn't be difficult to slightly tweak orbits so that they miss the cable by a couple dozen kilometers if not hundreds. Space is really big and mostly empty. eg. if needed, a big laser can sublimate away debris before it hits. Besides the materials-science problem, none of the other commonly raised technical challenges really seem as insurmountable as they're often hyped up as being. – Dragongeek Apr 09 '23 at 14:23
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    As bad as the material requirements are, the bigger problem is the economics. A space elevator would provide limited throughput with strictly limited payload and mass to a narrow range of orbits at an energy cost higher than the launch cost of reusable rocket launch systems. An inflation-adjusted minimum lift cost for the elevator in Edwards' study is around $360/kg, the equivalent minimum cost estimate for Starship is more like $20/kg...and that's probably a more accurate estimate, since the technology's far more developed. Who's even going to fund the space elevator's R&D? – Christopher James Huff Apr 09 '23 at 15:03
  • The problem with SE R&D is IMHO exactly because few people funding it. Rockets are somewhat cheap now precisely because it's a proven tech since a long time ago, thus a lot of money pours in. If SE received as much fund, its lift cost could reach down well below Starship stuff, I think. In the end, it boils down to material efficiency: rockets require so much to lift up so little, and I don't see anything that can change that fact even in the far future. Meanwhile, with the SE at least we can have hopes. We can't become a space-colonizing species with just rockets. – longtry Apr 10 '23 at 04:07
  • @longtry Edwards' estimate was based on the energy costs alone, and there's a vast amount of infrastructure required that must be paid for. The material cost of a rocket launch is minuscule, even Starship will cost less than $1M, possibly closer to $0.5M in propellant to launch. A space elevator would be a massive bottleneck, the Edwards study was for one that could only lift 6-9 Starship loads a year, and only to equatorial orbits. Rockets can scale to support space colonization, space elevators can not. – Christopher James Huff Apr 10 '23 at 12:40
  • What's the failure mode that can kill a fraction of the population? – ikrase Apr 11 '23 at 05:54

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