Could a balloon use non-fissile isotope, like Pu-238, to heat air in the envelope to stay afloat for years?
let's put political and health related problems aside, and consider if it's technically possible at all. Say, as an unmanned, high-altitude scientific/weather station.
I know that:
- Pu-238 has power output of 0.54 watts per gram
- Its half-life is 87.7 years (power output halves after that time).
- great most of the energy can be radiated out as heat, and transferred to surrounding air.
I don't know what buoyancy can the hot air balloons provide, and what kind of energy input they require to stay afloat. So - would it fly?