The invention is an aircraft having an inflatable wing connected to a base unit, with the inflatable wing inflated with a lifting gas such as helium. The inflatable wing has a series of cell structures, and may be configured with ballonets to selectively introduce and expel outside air within the inflatable wing to vary the buoyancy and/or airfoil properties of the inflatable wing. The aircraft is particularly useful at low speeds and in thin atmospheres (such as at high Earth altitudes and on Mars), and can be used for interplanetary missions to explore planetary bodies, such as moons and planets, having atmospheres.