Learn to walk before you run. As the article says, a self-contained environment capable of supporting multiple people, including their oxygen and food, while

Learn to walk before you run. As the article says, a self-contained environment capable of supporting multiple people, including their oxygen and food, while being able to contribute at least a little to their consumable use with local activity -- right here on Earth -- has never really been done. Perhaps an underground base in Antarctica? With a nuclear reactor and some hydroponics? Experimental local concrete production? Such a base would be an enormous project, sure to cost billions, would rely on technologies not yet invented, and would still be heavily dependent on regular supply deliveries for many decades. And that's doing it here on Earth, where the nearest city would be a day's flight away and poking a hole in the wall accidentally isn't a major concern.