“NASA's Pathfinder, Pathfinder Plus, Centurion and Helios Prototype were 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”. – Wikipedia

Photo: The solar-electric Helios Prototype flying wing is flies over the Hawaiian islands of Niihau and Lehua during the first solar-powered test flight July 14, 2001 from the U.S. Navy's Pacific Missile Range Facility on Kauai, HI. The 18-hour flight was a functional checkout of the aircraft's systems and performance in preparation for an attempt to reach sustained flight at 100,000 feet altitude later in the summer. (Photo Courtesy of NASA/Getty Images)

Meri Nirmala Sari, 11, poses in her traditional costume before a performance August 6, 2002 in Ubud, Bali, Indonesia. Meri dances with the Gunung Sari Peliatan dance group and has become a professional. She started dancing at age 5. (Photo by Paula Bronstein/Getty Images)

In this October 15, 2014 file photo, Katsu Nakamura, sky division manager for Yamaha USA, moves the RMax unmanned helicopter into position before a demonstration of its aerial application capabilities at the University of California, Davis' Oakville Station test vineyard in Oakville, Calif. Researchers at UC Davis have been studying the effectiveness of the drone's ability for spraying pest control and nutritional materials on the test vineyard in California's Napa Valley. (Photo by Rich Pedroncelli/AP Photo)

A man plays in front of a wave crashing into Beirut's Corniche, a seaside promenade, as high winds sweep through Lebanon ahead of an impending storm January 6, 2015. (Photo by Jamal Saidi/Reuters)

Emperor penguins gathered together to keep their chicks warm in these pictures. Marine scientist Frederique Oliver snapped the protective parents in Antarctica as they huddled against the huge winds.The adorable birds have to battle temperatures on -20 degrees Celsius as well as winds of up to 40 knots on the ice. (Photo by Frederique Oliver/Caters News)

Supporters of the presidential candidate Muhammadu Buhari and his All Progressive Congress hits with a motorbike another supporter during celebrations in Kano March 31, 2015. Nigeria's opposition APC declared an election victory on Tuesday for former military ruler Buhari and said Africa's most populous nation was witnessing history with its first democratic transfer of power. (Photo by Goran Tomasevic/Reuters)

“Misty Morning”. Every morning, people expect sunny weather. Photo location: Bali, Indonesia. (Photo and caption by Henry Adam/National Geographic Photo Contest)

In this October 7, 2014, photo, Fredrick Brower, center, helps cut up a bowhead whale caught by Inupiat subsistence hunters on a field near Barrow, Alaska. Drawing on tradition, and keeping within the closely monitored Aboriginal subsistence whaling guidelines, a bowhead whale is carved and divided by a crew armed with knives and hooks, and then shared according to custom. (Photo by Gregory Bull/AP Photo)