[gizmo686]

I am not aware of research on how much gravity is needed to maintain a healthy environment. For example, it is possible that an body as light as Pluto (with only .06 Gs) would offset the majority of the effects of low gravity. If this is the case, then permantant bases on Moons/Planets would face little issues from micro-gravity concerns. If humans require closer to 1G to remain healthy, then these bases become more difficult.

We have already demonstrated that humans can stay in space for over a year while remaining relativly healthy. Further, we can achieve artificial "gravity" with centrifugal force if we needed to.

Additionally, we could also attempt to solve the problem through medical science, and treat the effects of micro-gravity instead of outright preventing it.

[stuff4ben]

That's a great point. Makes me wonder why we're not getting that moon base setup. Seems like a natural first step prior to colonizing Mars. Learn how to survive on the Moon, take that knowledge and apply to Mars.