I find the idea of multiple shifts of the same importance on the same vessel odd. At least, I think that there should be 1 main crew (us) and then 1 or 2 people per station who replace us during our downtime, which can be at anytime the Captain chooses. I also think we only have 1 Captain on board, though I’m not sure about the First Officer.
Also, how long do our missions last? I doubt it’s just a few hours, since that seems like such a great expense.