Launching material into orbit is a hugely expensive business. But rather than lifting material from the bottom of the Earth’s deep gravity well, perhaps we can use material that’s already out there.
From http://kianorshahmohammadi.com/post/161137933570
source https://dentaleconomicsus.wordpress.com/2017/05/27/rv-jones-lecture-space-resources-engineering-beyond-planetary-boundaries-whats-on-the-university-of-aberdeen/