Ever since the space colonization visions of physicist Gerard K. O'Neill in the 1970s, colonizing space has captured the imagination of many. But even if launch costs were cut to a fraction of what they are now, ferrying all the items from Earth needed for a habitat in space isn't practical.

"We can't keep launching things like that into orbit, not if we're going to have long duration missions," said John Vickers, manager of the National Center for Advanced Manufacturing at NASA's Marshall Space Center.

That's why NASA is interested in building in space. There are certain advantages to this idea.

"You have near-infinite energy from the sun, an infinite heat sink, and a perfect vacuum," said Chris Lewicki, president and chief engineer at Planetary Resources, a company that has actually floated plans to mine asteroids. All three of those things are useful for several types of manufacturing on Earth.

There isn't any large-scale manufacturing in space yet, of course. To get there, launch costs will have to come down. "The best way to think of this is looking at industry before and after something brings the launch costs down," Jason Hay, senior analyst at the Tauri Group, a consulting firm that analyzes the space and defense industries, told InnovationNewsDaily.