I mean, really, there's nothing you could call it that doesn't sound pulp-y. I mean, really -- "Star Fleet?" "Space Force?" "Space Command?" "Star Command?" "Extrasolar Command?" Etc.
I mean, if you follow the name construction of the aeronautical military forces of most countries -- "Air Force" -- and apply it to space, what do you get? "Space Force." "Star Force." Etc. It sounds a bit silly. I'm sure that to people living in 1887, the term "Air Force" would have sounded ridiculous, too.
I just like the name 'Starfleet' (one word, not two
) the best of all. It gets rid of as much of the pulp, the cheesiness, the inefficiency, etc. as possible. Just one word: Starfleet. You can't get much clearer than that, really. I wonder who first came up with that word. Was it Gene? If so, my respect for the man just went up.
I did hear talk of a real-world movement to change the name of the actual USAF slightly, to United States Aerospace Force. I wonder if that was ever real, or just an urban legend.