szotz writes: There's a lot of skepticism swirling around NASA's plan to send humans to Mars in the 2030's, not to mention all those private missions. If we want to have sustainable (read: not bank-breaking) space exploration, the argument goes, there's no way we can do it the way we've been going to the moon and low-Earth orbit. We have to find a way to exploit space resources and cut down on the amount of stuff we need to launch from Earth. That's not a new idea. But this article in IEEE Spectrum suggests research on resource extraction and fabrication in low and zero gravity might actually be making progress...and that we could take these technologies quite far if we get our act together.