staging/undocking the return pod set hub to 0

[danielboro]

it was repeatedly mentioned that wen a return pod was undocked or the ship staged the kerbals turn tourists do to losing all/most hub parts.
i suggest that on hub change the new hub will be set to no less then X.
personally i think a day is a good number
but if the goal is just to allow a landing 20-60 minutes will probably be good

im thinking of sudden big hub changes that happen wen parts explode, a ship is staged or undocks so the kerbal are now in a smaller part but still same ship that now has less hub