“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)

The Haʻikū Stairs, also known as the Stairway to Heaven or Haʻikū Ladder, is a steep hiking trail on the island of Oʻahu. The trail began as a wooden ladder spiked to the cliff on the south side of the Haʻikū Valley. It was installed in 1942 to enable antenna cables to be strung from one side of the cliffs above Haʻikū Valley to the other. A building to provide a continuous communication link between Wahiawā and Haʻikū Valley Naval Radio Station was constructed at the peak of Puʻukeahiakahoe, elevation about 2,800 feet (850 m). The antennae transmitted very low frequency radio signals from a 200,000-watt Alexanderson alternator in the center of Haʻikū valley. The signals could reach US Navy submarines as far away as Tokyo Bay while the submarines were submerged.

A Catholic faithful holds a figurine of baby Jesus during a religious procession on Holy Innocents Day in Antiguo Cuscatlan, on the outskirts of San Salvador, December 28, 2014. Festivities are held every December 28 in honor of children, termed the Holy Innocents, below the age of two who were ordered to be killed by King Herod, according to biblical passages. (Photo by Jose Cabezas/Reuters)

Two workers shovel mud from the river as they look for gold on March 25, 2014 in Lampang, Thailand. Thai villagers from Wang Nuea, North of Thailand, look for gold in the river every year during the drought season. They are able to make an average around USD 15 per day, however two years ago they reached USD 200 in one day due to the river level dropping so much. The workers begin to search for gold at 10 AM and work until sunset, often working second jobs in the day in order to survive. (Photo by Borja Sanchez-Trillo/Getty Images)

Buddy the dog peers from a vehicle before the start of a movie at a drive in cinema in Snagov, Romania, Monday, June 1, 2020. Romania further loosened the measures imposed during a nationwide lockdown in order to limit the spread of the COVID-19 infections, with museums, open air restaurants, cinemas and beaches opening for public on Monday. (Photo by Andreea Alexandru/AP Photo)

Ultra-orthodox Jewish men wearing protective face masks swim in the Mediterranean Sea, on a beach segregated for males three days a week, in Tel Aviv, Israel, Wednesday, July 8, 2020. In an effort to quell the rapid spread of the coronavirus, Israel has re-imposed a series of restrictions on the public. This week, the Israeli government limited gatherings and ordered reception halls, restaurants, bars, theaters, fitness centers and pools be shut down again. (Photo by Oded Balilty/AP Photo)

A woman adjusts the Mantle of the Order of the British Empire at an exhibition at Buckingham Palace in London, Thursday, July 21, 2016. In celebration of Her Majesty's 90th birthday this year, visitors to the Summer Opening of the State Rooms at Buckingham Palace will enjoy an unprecedented display of The Queen's outfits, from childhood to the present day, in the special exhibition Fashioning a Reign: 90 Years of Style from The Queen's Wardrobe. (Photo by Frank Augstein/AP Photo)

Lancaster Gate station displays signage after being rebranded “Ratchet and Clankaster Gate” as the PS5 goes on sale in the UK, on November 19, 2020 in London, England. The first generational upgrade to Sony's line of Playstation consoles since 2013, the launch has seen pre-orders sell out within hours and websites crash as retailers attempt to keep up with demand. (Photo by Alex Davidson/Getty Images)