At least a dozen, with a few hundred people working spaceside full time
You could have human-crewed vehicles in orbit around various planets, tele-operating and managing things on their surfaces with much faster turnaround time than lightspeed delay to Earth. Depending on what's been found and what's being teleoperated, that could be worthwhile - consider the fact that our big $2 billion Mars rover moves something like 30 meters per day because with a 10+ minute turnaround time for signals, it's doing nothing most of the time since they want to make sure that everything it does is something they can recover from if something goes wrong and they don't know about it for fifteen minutes.
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