AeroVironment Pathfinder

The NASA Pathfinder and NASA Pathfinder Plus were the first two aircraft developed as part of an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles (UAVs). AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built 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. They were developed further into the NASA Centurion and NASA Helios aircraft.

Summary from Wikipedia, photo via Wikimedia Commons, licensed under CC BY-SA.