> likely because none of the NASA Centers is really focused on it. That's what I thought until I started looking into it. The module has actually been built (s

> likely because none of the NASA Centers is really focused on it. That's what I thought until I started looking into it. The module has actually been built (several versions in fact), but never completed and launched. It turned out during tests and simulations that the station's structural integrity was at risk and so it was decided not to attach a centrifuge to it. Whether these concerns were warranted I cannot say, but engineers at NASA deemed it too risky to try.