The Intermediate Lifeboat State

"I was baffled when she had much of the same explanation you did that it's kind of an intermediate lifeboat state," he said. "That's what I figured was that they're just going to shoot them all like dune, just shoot these giant structures through there." And then the reason that gravity is so important in the film is because basically they were already building the space stations but they were building them on Earth and then just leaving them outside as they couldn't get once they encountered them  in 1950 or whenever.