NASA wants to build another space station, but this one won’t live in a close orbit around Earth. Within the last year, NASA has begun planning for a much smaller astronaut outpost in orbit around the Moon, a new destination dubbed the Gateway. The idea is for this space station, which will be a fraction of the size of the International Space Station, to serve as a place for astronauts to live and train for excursions to and from the lunar surface. A crucial piece of hardware needed for this Gateway will, of course, be habitats — spaces for a...