Originally Posted by Mad Pistol
The biggest issue with nanotubes is that in early tests, it was proven that they can only be created in small strands and are toxic and can have nearly lethal effects if ingested or inhaled. Those were the issues. At this time, though, they may have found a way to overcome those obstacles.
Once you get past those potential setbacks, it really is a miracle particle. The strength of nanotubes is just unreal.
They're working on production methods, and already they can make tubes well over a meter long. They haven't managed 96,000km yet though.
As for toxicity that's only really with very small particles of nanotube that, on the nanometer scale, could be absorbed into cells and cause cell death; or micro scale nanotubes which could be inhaled into the lungs and cause asbestos-like effects. But when you get into macroscopic scales, in centimeters and meters and kilometers, there's really no health threat.