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The space elevator will make bringing cargo to/from earth trivial and it will happen way before asteroid mining (current estimates for it being built is 15-20 y

The space elevator will make bringing cargo to/from earth trivial and it will happen way before asteroid mining (current estimates for it being built is 15-20 years)

rapsey 2y ago
Wildly optimistic when there is no known material that can be used to build it.
- drexlspivey 2y ago
  Carbon nanotube is an existing material, manufacturing it at scale is one of the challenges.
  - troupo 2y ago
    manufacturing and building anything out of them in the required scale
  - Llamamoe 2y ago
    Carbon nanotubes are not even close to strong enough to build a space elevator, that's the whole problem. We have no idea if anything that strong even exists, at this point.
    - drexlspivey 2y ago
      > Carbon nanotubes are not even close to strong enough to build a space elevator, that's the whole problem. Do you have any sources for that? Because from a quick search online I’m seeing that SE requires a tensile strength of 60-80 GPa and the theoretical max strength of carbon nanotubes can reach 150-200 GPa (with a 63 GPa being demonstrated back in 2000)
      - adrian_b 2y ago
        Nobody can make a nanotube with a length of one meter, much less with a length of 1 km or of 100 km. We can imagine a molecular machine that would grow carbon nanotubes like a silkworm grows silk filaments, but we are many decades away from this kind of things. Moreover, the tensile strength is not all. It must resist to some intentional or accidental collisions, to earthquake waves and so on.
        DennisP 2y ago
        We don't need kilometers. We need lots of 7cm nanotubes, bonded together with epoxy. http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf
        adrian_b 2y ago
        That paper only presents hope that perhaps adhesive bonding of carbon nanotubes could produce a cable with high tensile strength. It does not contain any experimental results supporting this hope, because only a strength similar to steel has been obtained. Perhaps it will become possible to obtain a higher tensile strength than with other materials by this method, but it is likely that this will require longer nanotubes and perhaps some other kind of polymeric resin instead of epoxy. It is very difficult to find anything that has high enough adhesion to carbon.
        DennisP 2y ago
        Sure, the material had not been produced yet, and still hasn't. Getting all those long nanotubes to line up parallel is another of the hard parts. It's just a theoretical result. A key part of the design is for the glue to have a low enough melting point, so if the cable breaks, it melts on reentry and you don't get lots of little fluttery bits instead of a big super-strong cable wrapping around the planet.
    - DennisP 2y ago
      Here's a NASA-funded study from the early 2000s, arguing that a space elevator could be built as a paper-thin ribbon at least a meter wide, composed of carbon nanotubes 7cm long, bonded together with epoxy. http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf The study also addresses lots of other engineering issues. This work sparked a lot of subsequent R&D that is still ongoing. We're not yet able to actually make the ribbon described in the study, but we're getting there. Then again, if you're willing to rely on dynamic support, a minimal orbital ring could be built with materials we have today: https://en.wikipedia.org/wiki/Orbital_ring https://en.wikipedia.org/wiki/Orbital_ring
      - thethirdone 2y ago
        From the linked report: > The material required for construction of the cable is a carbon nanotube composite: currently under development and will be available in 2 years. Its actually crazy that the report thinks that we would have the necessary material in 2005 and is still used as evidence of a practical space elevator. The graph on page 10 shows the absolutely massive extrapolation from data at the time. It seems disingenuous to even talk final price and time to construct a space elevator (as is done in the one-page brief) without any data confirming the possibility of manufacturing the goal material.
        DennisP 2y ago
        It was definitely way overoptimistic on making the material. But it does present a pretty interesting design, for whenever the material becomes available.
theptip 2y ago
Tether / skyhook seems a more plausible option.
Ekaros 2y ago
15-20 years? I would doubt that range if the process was started yesterday. Any reasonable complex project of closing that scale takes longer time than that. And those have no real unknowns.
- goldfishgold 2y ago
  CA high speed rail has taken 16 years so far with another 15 on the horizon, and that required 0 novel technology.
BriggyDwiggs42 2y ago
I sure hope you’re also betting on a superintelligent ai that can solve every single problem for a 15-20 year timeline

The space elevator will make bringing cargo to/from earth trivial and it will happen way before asteroid mining (current estimates for it being built is 15-20 years)

rapsey 2y ago

Wildly optimistic when there is no known material that can be used to build it.

drexlspivey 2y ago
Carbon nanotube is an existing material, manufacturing it at scale is one of the challenges.
- troupo 2y ago
  manufacturing and building anything out of them in the required scale
- Llamamoe 2y ago
  Carbon nanotubes are not even close to strong enough to build a space elevator, that's the whole problem. We have no idea if anything that strong even exists, at this point.
  - drexlspivey 2y ago
    > Carbon nanotubes are not even close to strong enough to build a space elevator, that's the whole problem. Do you have any sources for that? Because from a quick search online I’m seeing that SE requires a tensile strength of 60-80 GPa and the theoretical max strength of carbon nanotubes can reach 150-200 GPa (with a 63 GPa being demonstrated back in 2000)
    - adrian_b 2y ago
      Nobody can make a nanotube with a length of one meter, much less with a length of 1 km or of 100 km. We can imagine a molecular machine that would grow carbon nanotubes like a silkworm grows silk filaments, but we are many decades away from this kind of things. Moreover, the tensile strength is not all. It must resist to some intentional or accidental collisions, to earthquake waves and so on.
      - DennisP 2y ago
        We don't need kilometers. We need lots of 7cm nanotubes, bonded together with epoxy. http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf
        adrian_b 2y ago
        That paper only presents hope that perhaps adhesive bonding of carbon nanotubes could produce a cable with high tensile strength. It does not contain any experimental results supporting this hope, because only a strength similar to steel has been obtained. Perhaps it will become possible to obtain a higher tensile strength than with other materials by this method, but it is likely that this will require longer nanotubes and perhaps some other kind of polymeric resin instead of epoxy. It is very difficult to find anything that has high enough adhesion to carbon.
        DennisP 2y ago
        Sure, the material had not been produced yet, and still hasn't. Getting all those long nanotubes to line up parallel is another of the hard parts. It's just a theoretical result. A key part of the design is for the glue to have a low enough melting point, so if the cable breaks, it melts on reentry and you don't get lots of little fluttery bits instead of a big super-strong cable wrapping around the planet.
  - DennisP 2y ago
    Here's a NASA-funded study from the early 2000s, arguing that a space elevator could be built as a paper-thin ribbon at least a meter wide, composed of carbon nanotubes 7cm long, bonded together with epoxy. http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf The study also addresses lots of other engineering issues. This work sparked a lot of subsequent R&D that is still ongoing. We're not yet able to actually make the ribbon described in the study, but we're getting there. Then again, if you're willing to rely on dynamic support, a minimal orbital ring could be built with materials we have today: https://en.wikipedia.org/wiki/Orbital_ring https://en.wikipedia.org/wiki/Orbital_ring
    - thethirdone 2y ago
      From the linked report: > The material required for construction of the cable is a carbon nanotube composite: currently under development and will be available in 2 years. Its actually crazy that the report thinks that we would have the necessary material in 2005 and is still used as evidence of a practical space elevator. The graph on page 10 shows the absolutely massive extrapolation from data at the time. It seems disingenuous to even talk final price and time to construct a space elevator (as is done in the one-page brief) without any data confirming the possibility of manufacturing the goal material.
      - DennisP 2y ago
        It was definitely way overoptimistic on making the material. But it does present a pretty interesting design, for whenever the material becomes available.

theptip 2y ago

Tether / skyhook seems a more plausible option.

Ekaros 2y ago

15-20 years? I would doubt that range if the process was started yesterday. Any reasonable complex project of closing that scale takes longer time than that. And those have no real unknowns.

goldfishgold 2y ago
CA high speed rail has taken 16 years so far with another 15 on the horizon, and that required 0 novel technology.

BriggyDwiggs42 2y ago

I sure hope you’re also betting on a superintelligent ai that can solve every single problem for a 15-20 year timeline