I saw a piece on television the other day about how debilitating being in space can be. The lack of gravity causes muscles to atrophy, even though astronauts pursue a rigorous exercise regimen. The possibility of creating artificial gravity by spinning our spacecraft was mentioned, but NASA apparently thinks this proposal is too expensive.
NASA's attitude is very curious. Many of my generation are surprised that spinning space stations have received so little attention. Walt Disney was telling us in the '50s that this was they way to go, and 2001: A Space Odyssey made it look so reasonable. My own theory is that NASA has painted itself into a corner. It has emphasized microgravity experiments because selling space as a place to do commercial fabrication impossible on earth is a more effective pitch to politicians and businessmen than is selling the idea of exploring the universe. If you cannot spin everything, why spin anything? Another problem is that NASA, until recently, seemed to be redesigning its current space station every second Thursday. Something large that spins in space requires a plan you stick with. On the other hand, a gravity-less and amorphous assemblage of stuff is always easy to add to.