In this January 27, 2019, photo, Hindu holy men of monastic order Juna Akhara participate in a ritual before becoming Naga Sadhus or naked holy men at Sangam, the confluence of three holy rivers during the Kumbh Mela or pitcher festival in Prayagraj Uttar Pradesh state, India. At every Kumbh, including this year's, thousands of devotees were initiated into the reclusive sect of the Naga Sadhus, naked, ash-smeared cannabis-smoking Hindu warriors and onetime-armed defenders of the faith who for centuries have lived as ascetics in jungles and caves. (Photo by Rajesh Kumar Singh/AP Photo)

An environmental activist performs during a protest in front of the headquarters of Brazilian mining company Vale SA in downtown Rio de Janeiro, Brazil, November 16, 2015. The collapse of two dams at a Brazilian mine, owned by Vale SA and BHP Billiton Ltd, has cut off drinking water for quarter of a million people and saturated waterways downstream with dense orange sediment that could wreck the ecosystem for years to come. Nine people were killed, 19 are still listed as missing and 500 people were displaced from their homes when the dams burst at an iron ore mine in southeastern Brazil on November 5. (Photo by Sergio Moraes/Reuters)

“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 Pioneer Team, a civil aerobatic team from Italy, let off pyrotechnics from their Pioneer 330 aircraft during the Malta International Airshow off SmartCity Malta, outside Valletta, Malta, September 24, 2016. (Photo by Darrin Zammit Lupi/Reuters)

A passenger aircraft passes over a residential house as it prepares to land at London Heathrow Airport in west London on October 17, 2016. Britain's government is considering whether to approve a third runway at Heathrow or expand air capacity in southeast England at another airport such as London Gatwick. (Photo by Daniel Leal-Olivas/AFP Photo)

An OV-10 Bronco aircraft, decorated with World War One commemoration motifs, flies over Flanders international airport, ahead of the world's first Short Take Off & Landing competition on sand, in Wevelgem, Belgium May 8, 2018. (Photo by Francois Lenoir/Reuters)

“The Antonov An-124 Ruslan (NATO reporting name: Condor) is a strategic airlift jet aircraft. It was designed by the Soviet Union's Antonov design bureau. It is the world's largest ever serially-manufactured cargo airplane and world's second largest operating cargo aircraft. During development it was known as Izdeliye 400 in house, and An-40 in the West. First flown in 1982, civil certification was issued on 30 December 1992”. – Wikipedia

Photo: The new metro called “Bombardier MOVIA” with 22,50 meters long and 3,2 meters wide is load on a Antonow An-124 plane for transport to India on February 25, 2009 in Parchim, Germany. (Photo Handout Bombardier Transportation via Getty Images)

A Romanian honor guard soldier stands still as three military aircraft carriers are crossing the sky during a ceremony held at the Unknown Soldier Memorial, in Carol I Park, on the occasion of the Heroes' Day commemoration, in Bucharest, Romania, 10 June 2021. (Photo by Robert Ghement/EPA/EFE)