I was watching a NASA Channel program that discussed bone mass loss for astronauts while in space. Their studies concluded that, on average, an astronaut losses 1% of their bone mass, per month, while in space. They didn't mention if that loss was recovered or regenerated, once the astronaut was back on earth? Ron Schenk, Alexandria, LA

Bone loss should be viewed as the ultimate wisdom of nature, the biology of the body is redesigning itself to new requirements -- i.e. zero gravity. With return to earth, it comes back to the old earth based design. Too many people, including NASA tend to think upon boneloss and other changes as detrimental when in fact they are the wisdom of adaptation, the right thing to be doing.