Abstract: A lighter than air aircraft has a non-jettisonable ballast comprised of a liquefied lighter than air gas contained within an insulated container. The liquefied gas is vaporized and released into the lift compartment of the aircraft which is at least partially filled with a lifting gas. A heat exchanger, separate from the means delivering the vaporized gas to the lift compartment, increases the temperature of the vaporized gas prior to entry of the vaporized gas into the lift compartment, wherein the vaporized gas becomes mixed together with lifting gas and whereby damage to the compartment by excessive cooling is minimized.