AeroVironment’s Helios solar powered unmanned air vehicle established the world altitude record for sustained horizontal flight in August 2001 by climbing to 96,863 feet. Powered only by the sun’s rays, Helios was the fourth in a series of solar powered unmanned aircraft developed by AeroVironment for NASA’s Environmental Research Aircraft and Sensor Technology (ERAST) program.

The purpose of the ERAST program was to develop the technologies that would allow long-term, high-altitude aircraft to serve as “atmospheric satellites,” to perform atmospheric research tasks as well as serve as communications platforms.

Today, AV is developing the Global Observer UAS to provide a platform offering “affordable persistence” for a variety of government and commercial missions. Whereas solar powered aircraft are generally limited to latitudes enjoying high level of solar energy year-round, the liquid hydrogen powered Global Observer will be capable of flying in the stratosphere over any spot on the globe, at any time, providing remote observation and data relay. A system of two or more Global Observer aircraft would alternate over the target area to ensure persistent coverage.

Read more about these projects: Helios and Global Observer.