A lighter-than-air aircraft includes a gas envelope for containing a buoyant gas, and a propulsion system is carried by the gas envelope. A solar panel is carried by the gas envelope for powering the propulsion system when generating sufficient power. A closed loop combustion generating system is also carried by the gas envelope for powering the propulsion system when the solar panel is not generating sufficient power. The fuel for the closed loop combustion generator is regenerated by the solar panel from its exhaust when the solar panel is generating sufficient power.