Imagine designing and creating a rope only an inch thick, able to stretch, without breaking, 2-4 times its normal length but strong enough to stop a huge airliner. Then add to the requirements that it can’t be made of metal, but only of spider silk. Impossible, you say. Actually it’s very realistic.
The strands spiders use to spin webs are stronger than steel, more resilient than Kevlar — the material that bulletproof vests are made of — yet finer than a human hair. If you could somehow weave spider webs into a cable, you’d have that airplane-stopping tether.