Would it be feasible/practical to construct a large floating space telescope that perhaps would be incorporated into the structure of a large dirigible, blimp or balloon. Or perhaps it would simply be carried aloft by the said buoyant platform? Has anyone ever before proposed the construction of such an observation platform? Couldn't this enable better-than-Hubble observation on the cheap? I realize that adaptive optics has greatly advanced the field of astronomy and reduced the handicaps that ground-based observatories have traditionally faced. But space telescopes like Hubble still provide unique and important information. Additionally, a floating telescope would be mobile, and able to shift locations and orientation in a way that fixed ground-based telescopes can't. So tell me, is this a useful idea worth consideration? Comments?