sanjurotokage
Acolyte
The tv series did mention there was mandatory requirement to return to Earth for a period due to this. It would be down time and sometimes it lead to cases on earth like visiting flooded Venice (in the universe it is underwater)Been thinking about the zero gravity environment. My thought that anyone with a job requiring an extended period in zero-G will need to spend at least a month on Earth to rebuild bone and muscle mass between assignments. Temporary trips/assignments in zero-G don't require this. Spending time on the Moon will extend the length of time before you need to return to Earth. (Riffing on my mother's days working in Egypt in the 1940s/1950s; you got a week or 2 local leave every year, and every 2-3 years you got an extended home leave.)
This would be monitored using bone densitometry. There would be a set-up on the Moon and any major space station with a large permanent population. All manned installations have a gym with resistance training, and all personnel are expected to exercise for at least 2 hours daily (missed exercise periods are to be made up when feasible). Larger installations may have a centrifuge ring to simulate gravity; often sleeping areas are located in the ring.