This article appears in the August Issue of VICE Magazine The first serious blueprint for building cities in space was drawn almost on a whim. Forty years ago this summer, dozens of scientists gathered in the heart of Silicon Valley for one of NASA's design studies, which were typically polite, educational affairs. But in 1975, the topic of inquiry was "The Colonization of Space," a recent paper by the astrophysicist Gerard O'Neill."The idea was to review his ideas and to see if they were technically feasible," said Mark Hopkins, an economist who was there. "Well, they were." So the scientists had a choice—set about laying the groundwork for real, no-bullshit space colonization, or hold the regularly scheduled series of seminars. "We said, 'To hell with that,'" Hopkins recalled. The ten-week program became a quest to outline a scientifically possible and economically viable way to build a human habitat in space.What they came up with—designs for huge, orbital settlements—are still pretty much the basis for all our space digs today, science-fictional or otherwise. The Stanford torus, a giant, mile-diameter space doughnut that rotates to create artificial gravity, should look familiar: The off-world cities in Elysium and Interstellar are inspired by the concept. The torus, which scientists conceived to house 10,000 people, would need 10 million tons of mass and a radiation shield made from space metal.At the beginning of the study, Hopkins said, more than half the attendants were skeptical. By August, nearly everyone—physicists, engineers, and economists alike—was convinced the space colonies were technically feasible. Now, 40 years since the first bona fide plans to set up shop in orbit, space colonies are officially over the hill. NASA hired artists to enshrine the concepts—influenced by the psychedelia of the era, they sort of look like 2001 on ayahuasca. Today, they're a staple of internet retroculture."One of the things going on in my mind was, why can't we have a space movement?" Hopkins said. For the record, he remains a staunch space-colonization advocate. "It's only a matter of time before it happens."