I've thought for a long time that colonization will probably never take off, but space industry is absolutely a good idea. Building colonies on mars is sort of

I've thought for a long time that colonization will probably never take off, but space industry is absolutely a good idea. Building colonies on mars is sort of like building colonies in Death Valley, or in the Marina trench, or inside the reactor cupola of Chernobyl. You could probably do it, but it's expensive, and nobody in their right mind would come. Once you've spent a ton of fuel getting out of a gravity well, you'd be insane to go down another one, especially if the only thing you're going to get from it is radiation poisoning. Space, on the other hand, offers some really interesting opportunities for manufacturing. It's effectively a gigantic clean-room, allowing for a whole load of processes you can't do on earth - like no-heat welding.