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. 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.
NASA Pathfinder
Pathfinder-Plus in flight over Hawaii, June 2002, equipped with Skytower communications equipment
Pathfinder-Plus on display at the Udvar-Hazy Center
Pathfinder Plus (left) and Helios Prototype (right) on the Dryden ramp
Solar energy is radiant light and heat from the Sun that is harnessed using a range of technologies such as solar power to generate electricity, solar thermal energy, and solar architecture. It is an essential source of renewable energy, and its technologies are broadly characterized as either passive solar or active solar depending on how they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power, and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light-dispersing properties, and designing spaces that naturally circulate air.
The Sun produces electromagnetic radiation that can be harnessed as useful energy.
Solar water heaters facing the Sun to maximize gain
Parabolic dish produces steam for cooking, in Auroville, India.
Solar water disinfection in Indonesia