So figure a Space Force impressive enough to satisfy Donald Trump and everybody else in Washington or Moscow or Tehran or Peking is going to cost about 250 billion dollars a year. We aren’t debating the number any more — we’re just all bickering about how fast we get to it. Which likely explains why there’s been so much foot dragging.

Maybe it’ll all be cheaper if the “starship trooper” types of the future were all stuck on earth, manning PC consoles while AI-equipped spacecraft hundreds of miles overhead fly from satellite to satellite, looking for potential threats, and software decides what deserves to be blown up. Maybe we can deploy a handful of robot night watchmen to prowl about unmanned outposts far away and Joke about the “space marines.” But I suspect it’s inevitable that if humans go into space in any permanent way, soldiers will go along with the settlers and the scientists.