I’m not really up to speed on that, being more on the electronics end. Still, I’ve maintained interest.
Personally, every year or so I check in with the NASA contest to see how they’re doing.
Last I heard, pure carbon nanotube yarn was a little stronger by weight than copper wire. Adding a little binder helps a lot.
Pugno’s assumption of 100 nm long tubes is very odd—you can grow much longer tubes, even in fair quantity. Greater length helps a lot. The main mechanism of weakness is slippage, and having longer tubes provides more grip between neighboring tubes.
This is more in the realm of a nitpick, though. If I were to ballpark how much of a tensile strength discount we’d have to swallow on the way up from nanoscale, I would have guessed about 50%, which is not far off from his meticulously calculated 70%.
I’d love for space elevators to work; it’s not looking promising. Not on Earth, at least. Mars provides an easier problem: lower mass and a reducing atmosphere ease the requirements on the cable. My main hope is, if we use a different design like a mobile rotating skyhook instead of a straight-up elevator, we could greatly reduce the required length, and also to some extent the strength. That compromise may be achievable.
I’m not really up to speed on that, being more on the electronics end. Still, I’ve maintained interest. Personally, every year or so I check in with the NASA contest to see how they’re doing.
http://www.nasa.gov/offices/oct/early_stage_innovation/centennial_challenges/tether/index.html
Last I heard, pure carbon nanotube yarn was a little stronger by weight than copper wire. Adding a little binder helps a lot.
Pugno’s assumption of 100 nm long tubes is very odd—you can grow much longer tubes, even in fair quantity. Greater length helps a lot. The main mechanism of weakness is slippage, and having longer tubes provides more grip between neighboring tubes.
This is more in the realm of a nitpick, though. If I were to ballpark how much of a tensile strength discount we’d have to swallow on the way up from nanoscale, I would have guessed about 50%, which is not far off from his meticulously calculated 70%.
I’d love for space elevators to work; it’s not looking promising. Not on Earth, at least. Mars provides an easier problem: lower mass and a reducing atmosphere ease the requirements on the cable. My main hope is, if we use a different design like a mobile rotating skyhook instead of a straight-up elevator, we could greatly reduce the required length, and also to some extent the strength. That compromise may be achievable.