NASA has unfortunately been neglecting low-gravity (centripetal acceleration) research.  The only research I am aware of in this area was conducted by the Soviet Union on mice, and (to the best of my recolection) they found that ~0.3G and relatively low RPM were required to maintain fitness.  I agree with you that further work is required on this subject, as it could help future Martians to be healthier and more productive throughout their journey, but it does not seem to jive with NASA&#x27;s current priorities.  NASA has repeatedly rejected proposals for studies and experiments in this area.