I saw a bit of a show on the Discovery Channel or something that was about some of the studies that are done to simulate the long term effects of being weightless in space. They were saying how these studies were important, especially if we are to venture farther and farther away, for the astronauts bodies have to be able to withstand the extended durations in space. Without gravity, bones get brittle, blood pressure gradients throughout the body are messed up and who know what else goes on.
The part that fascinated me was the part where they showed one of their simulated microgravity studies on healthy volunteers. The volunteers were wheeled around on gurneys and had to remain essentially motionless for months at a time. Can you even imagine how horrible that would be? Where do they even find people that would volunteer to do that? How much must they pay them to stay still for months on end? Would you ever participate in such a study for say, three months, and if so, how much would they have to pay you to get you to do it?