The high altitude long endurance (HALE) unmanned aerial vehicle (UAV) is designed to fly at 60,000 feet for months at a time, providing a carrier for a highly accurate and low cost alternative to expensive satellite (Launching cost is around $25000/kg of payload). HALE systems use advanced aircraft or airship technologies to provide mobile, usually uninhabited, platforms operating at altitudes in excess of 20 Km (stratospheric platforms).

The HALE platform would have many of the advantages of both terrestrial and satellite systems, while at the same time avoiding many of their pitfalls. Additional applications of HALE platforms include the ability to provide superior remote sensing performance compared to satellite systems for a wide range of civil applications involving time-varying or emerging phenomena (e.g. environmental science, atmospheric science, communications, ocean monitoring, law enforcement, customs, immigration, urban planning and monitoring, road traffic monitoring, pollution control and others) and for a wide range of military applications including imagery intelligence, signal intelligence, electronic warfare and military search and rescue.

HALE unmanned missions appear to be feasible using a lightweight, high efficiency, span-loaded, Solar Powered Aircraft (SPA) which includes a Regenerative Fuel Cell (RFC) system and novel tankage for energy storage. However, this design has complexity and weight penalties associated with thermal management, electrical wiring, plumbing, and structural weight. Another way to enable practically unlimited endurance is to supply the energy required for propulsion and payloads remotely. The dominating attention in this area has been given to the use of microwave transmission from ground, through a focused beam, to a receiving antenna on-board the aircraft.

None of the aircraft can carry large payloads (2,000 kg or more) at high altitudes and remain aloft for months at a time. An airship can do this. Because the airship uses buoyancy for its lift, it does not require as much power as a vehicle that derives its lift by propelling itself through the atmosphere. Consequently, airships do not need to stay in motion to remain aloft. Therefore, they can loiter over a specific location as well as move to a new location. In addition, airships can carry large-volume, heavy payloads. These characteristics make airships superb candidates for long-endurance surveillance missions.

However, a renewable energy airship, issues a challenge to design the power system, the propulsion system, and the craft