“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)

Families and relatives of the dead cry as they identify their family members at a temporary burial ground March 25, 2011 in Higashi Matsushima , Japan. (Photo by Paula Bronstein /Getty Images)

Regrowth of plants is seen in bushland that was destroyed by bushfires, in Kulnura, New South Wales, 15 January 2020. (Photo by Joel Carrett/EPA/EFE/Rex Features/Shutterstock)

A sculpture made by activists on Lambeth bridge during the Extinction Rebellion protest in London, England on October 7, 2019. (Photo by Henry Nicholls/Reuters)

Maya Nakanishi of Japan competes en route to winning the women's T64 long jump at the World Para Athletics Championships in Dubai on November 11, 2019. (Photo by Christopher Pike/Reuters)

A man wears a gas mask as he holds a bouquet of flowers, following the outbreak of the novel coronavirus on Valentine’s Day in Hong Kong, China on February 14, 2020. (Photo by Tyrone Siu/Reuters)

Guards wait for the start of former Egyptian President Hosni Mubarak's funeral at Field Marshal Mohammed Hussein Tantawi Mosque east of Cairo, Egypt on February 26, 2020. (Photo by Amr Abdallah Dalsh/Reuters)

Barber Herman Mulyana (R) gives a haircut to a customer while wearing protective attire made from plastic garbage bags at a barbershop in Bogor, Indonesia, 06 April 2020. The Trade Ministry of Indonesia issued a regulation temporarily recinding all requirements for the import of protective gear and medical equipment, to counter shortages of many items used to treat COVID-19 patients and prevent the further spread of the disease. (Photo by Adi Weda/EPA/EFE)