Water stablization of rotating haitats.

[JoeStrout]

I'm skeptical about stopping (let alone reversing) the spin of a habitat just from shifting the water it contains — for this to work, your habitat would have to be mostly water, or your water would have to be circulating at hundreds of miles per hour, or both, for this to work.

But yes, you certainly could make minor adjustments to the spin and (more practically) keep the colony properly balanced around its spin axis by shifting water between reservoirs.

I even suspect (but have not proven to my satisfaction) that if you had a continuous river all the way around a habitat, that it would naturally rebalance the habitat without any pumping at all.  The reasoning goes like this: suppose the habitat gets a little off center.  Now one side is further from the spin axis, and thus feeling more pseudogravity.  Water will flow in that direction, shifting the center of mass in that same direction as well.  This will stop when the center of mass starts to get closer to that side, with the end result that everything should stay perfectly balanced.

I'm not 100% sure that's true, but it'd sure be nifty if it is.  And it could be tested in a benchtop experiment by some enterprising youth as a science fair project!