“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)

A group of people are seen on a Victoria line train in London, England during the first night of the Night Tube service on August 19 2016. The Central line and Victoria line are the first to operate a Night service with further lines expected to be running by the end of the year. (Photo by SWNS.com)

A man retrieves fans from a collapsed shop following a strong earthquake in Meureudu, Pidie Jaya, Aceh province, Indonesia December 8, 2016. (Photo by Darren Whiteside/Reuters)

Cristine Angelie Garcia (C), 24, rides a jeepney on her way to work at a call centre for the midnight shift in Taguig city, Metro Manila, Philippines October 3, 2016. “Maybe there is another way where people do not need to die”, she said, adding she felt safer walking the streets at night. “I'm on Duterte's side. Maybe he's just misunderstood because he grew up on the streets”. (Photo by Ezra Acayan/Reuters)

A mahout bathes his elephant in the river Sabarmati on a hot summer day in Ahmedabad, India May 21, 2017. (Photo by Amit Dave/Reuters)

Filipino children frolic next to ships taking shelter inside a seaport in Navotas city, north of Manila, Philippines, 27 August 2019. According to the latest advisory from Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA), Tropical Storm Podul intensified from a tropical depression into a tropical storm on August 27, while moving toward Central Luzon with a maximum winds of 65 kilometers per hour and gustiness of up to 80 km/h. (Photo by Francis R. Malasig/EPA/EFE)

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 walks into the The Life Tabernacle megachurch as local residents attend Sunday service challenging state orders against assembling in large groups to prevent the spread of coronavirus disease (COVID-19) in Baton Rouge, Louisiana U.S., April 5, 2020. (Photo by Carlos Barria/Reuters)