At this point it’s pretty clear that with low enough launch costs orbital industry will be a big thing. All sorts of high performance materials can only be made in microgravity:
* Better optical fibers with ZBLAN (happening today) and better optics in general with zero-g glass forming
* whole new alloys which can’t be made in normal g due to density separation. Think better nickel superalloys, and guess what the price per kg could be
* much larger, purer, more perfect crystals of all sorts for semiconductors, drug development, etc
* artificial tissues and organs grow better when not under their own weight
Launch costs are dropping fast today, but will eventually probably plateau someplace north of $50/kg until we can move past chemical rockets, which IMO is fantasy in our lifetime.
As long as launch costs stay that high, it’s strong incentive to develop mining and refining capacity on Mars. The gravity well is so much shallower than Earth that for any destination past LEO, you’re saving money launching from Mars.
Martian materials won’t be used on Earth for centuries, if ever. But $50,000 / ton Martian steel + Martian launch costs will be cheaper than ~free Earth steel + Earth launch costs within our lifetimes, imo.