Robot arms are a complex control problem all on their own. To catch the rocket they'd have to be very fast, and very precise. At the same time, the rocket's con

Robot arms are a complex control problem all on their own. To catch the rocket they'd have to be very fast, and very precise. At the same time, the rocket's control loops already have only a very small margin for error. A small miss by either system and you have a much higher chance of failure. In terms of a net, I imagine something that's lying on the deck under tension between four bendy rods. When the rocket is close enough, the rods snap over to the other side, furling the rocket in the net and holding it more or less steady.