I think both fiberglass and carbon fiber use organic epoxy that’s prone to UV (and atomic oxygen) degradation? One solution is to avoid epoxy entirely using parallel strands or something like a Hoytether. The other option is to remove old epoxy and reapply over time, if its economical vs just letting the tether degrade.
I worry that low-thrust options like ion engines and sails could be too expensive vs catching falling mass, but I could be convinced either way!
Yeah, some form of vibration damping will be important, I glossed over this. Bending modes are particularly a problem for glass. Though I would guess that vibrations wouldn’t make the force along the tether any higher?
Catching the projectile is a key engineering challenge here! One that I probably can’t solve from my armchair. As for missing the catch, I guess I don’t see this as a huge issue? If the rocket can re-land, missing the catch means that the only loss is fuel. Though colliding with the tether would be a big problem.
Yeah I think low orbits are too challenging for tethers, so they’re definitely going to be at risk of micrometeorite impacts. I see this as a key role of the “safety factor”. Tether should be robust to ~10-50% of fibers being damaged, and there should be a way to replace/repair them as well.
Right, though tethers can’t help satellites get to LEO, they can help them get to higher orbits which seems useful. But the real value-add comes when you want to get to the Moon and beyond.
Good to know! I would love to see more experiments on glass fibers pulled in space, small-scale catches, and data on what kinds of defects form on these materials in orbit.
Thanks for the comments! Going point-by-point:
I think both fiberglass and carbon fiber use organic epoxy that’s prone to UV (and atomic oxygen) degradation? One solution is to avoid epoxy entirely using parallel strands or something like a Hoytether. The other option is to remove old epoxy and reapply over time, if its economical vs just letting the tether degrade.
I worry that low-thrust options like ion engines and sails could be too expensive vs catching falling mass, but I could be convinced either way!
Yeah, some form of vibration damping will be important, I glossed over this. Bending modes are particularly a problem for glass. Though I would guess that vibrations wouldn’t make the force along the tether any higher?
Catching the projectile is a key engineering challenge here! One that I probably can’t solve from my armchair. As for missing the catch, I guess I don’t see this as a huge issue? If the rocket can re-land, missing the catch means that the only loss is fuel. Though colliding with the tether would be a big problem.
Yeah I think low orbits are too challenging for tethers, so they’re definitely going to be at risk of micrometeorite impacts. I see this as a key role of the “safety factor”. Tether should be robust to ~10-50% of fibers being damaged, and there should be a way to replace/repair them as well.
Right, though tethers can’t help satellites get to LEO, they can help them get to higher orbits which seems useful. But the real value-add comes when you want to get to the Moon and beyond.
Good to know! I would love to see more experiments on glass fibers pulled in space, small-scale catches, and data on what kinds of defects form on these materials in orbit.