Thanks Bruce.
Centrifugal force. I wonder why they didn't do that on the ISS. Probably money, engineering and...logistics. That, and they didn't expect people to stay longer than a year. So the rehab they got after returning was enough.

I accidentally watched part of a show on something like the Discovery channel. "Mars". It was a documentary ("mockumentary"?)about how the colony on Mars came to be. Have you seen it?