Read the full article "The Men Who Made Space Colonies Look Like Home" here. 

In the mid-1970s, to a visionary few, space colonies seemed like the future of humanity. One of the colony types deemed feasible was the cylinder colony, here shown in a double-cylinder version envisioned by Gerard O'Neill, a Princeton physicist.

Rick Guidice, the painter who made this image for a NASA report on space colonies, explains what's going on here. The cylinders sport haloes of agriculture pods, he says. The pods "rotate themselves, they have their own gravity, and they pivot on those rings that go all the way around. On the end of these cylinders was a zero-gravity manufacturing area, where manufacturing and producing energy or whatever else they were doing that was best suited for zero gravity took place.” The machinery rendered at the end of the cylinders, though, isn't specific. “I just invented all that. Space-stuff.”

The cylinders are fitted with long glass windows and matching mirrors that angle outwards. “The idea with the big mirrors and the windows is that they’re opening and closing to create night and day. The cylinders point directly at the sun, so there’s no sun going directly in the windows. At night these large reflectors close up and can protect the glass and stop the sunlight to create night. Then they open up slowly to create day, open more and more until it’s finally open about noon, and then start closing down slowly in the afternoon to replicate the sun throughout the day.”