(CNN) – It’s early evening and you’re with friends, enjoying a drink or two. The sun is shining after all and it’s been a long week.
The river nearby shimmers in the light. You follow its course, your eyes gradually moving up, up, over your head and then down to the other side.
Eventually the water meets in a perfect circle, back where you began. Everything is as it should be. You’re a resident of a Bernal Sphere, floating on the far side of the Moon — you’re used to the artificial gravity by now.
As retrofuturist artwork goes, few reach the outlandish heights of Rick Guidice and Don Davis, commissioned by NASA in 1975 to illustrate potential space colonies.
The designs sprang from the mind of a team at the NASA Ames Research Center, spearheaded by Gerard O’Neill, a Princeton professor given grants by the American space program to conduct a ten week study into off-world structures.
Working with architects, researchers, engineers and scientists in Mountain View, California, O’Neill assessed whether his ideas were feasible, eventually drawing up three concepts to present to NASA: the Bernal Sphere, the Toroidal Colony and the Cylindrical Colony.