> You might ask yourself, how are you going to come back down to earth if you cannot release some of the hydrogen/helium? If the material can be compressed to

> You might ask yourself, how are you going to come back down to earth if you cannot release some of the hydrogen/helium? If the material can be compressed to 95% it's size and reexpands, you just compress your tanks and lower back down, expand tanks to rise. ( all concerns of other comments having been solved with the standard wave of the hand )