We know about the debilitating effects of microgravity on the human body. Some of these, such as loss of muscle tone and bone mass, can be mitigated by a program of strenuous and time-consuming regular exercise, but others, including suppression of the immune system and increased pressure within the brain cavity and eye, have no known ways to avoid. We have no long-term experience at all with the effects of lunar (1/6) or Martian (1/3) gravity and thus no way to estimate its effects on those spending long periods in those environments.
With discussion of lunar and Mars settlements and large numbers of people travelling to them, it’s time to actively consider artificial gravity produced by rotating spacecraft, both to avoid the effects of microgravity and to simulate lunar and Martian gravity in an environment closer to home. Will Starship provide the mass to orbit and payload volume to begin this work?