well most balloons will also drop to the earth because they lose helium (or hydrogen, or whatever gas). i'm not claiming to know exactly how it all works, but in my opinion they are using balloons to enter into supersensible realms. rocket fuel won't work. any rocket they launch might be able to delivery a payload up to the sky but it isn't going to stay up there unless they have a gas 'balloon' of some kind. probably shouldn't be talking about this though.
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