A man rides his motorcycle along an empty street in Cali on April 17, 2021, during a curfew imposed by the government to help curb infections of the novel coronavirus, COVID-19, as weekend partial lockdown takes effect in four Colombian cities. In recent weeks, the Colombian government has imposed, and then tightened, a series of restrictions to stem a third wave of infections that is bringing its health system to the brink of collapse. (Photo by Luis Robayo/AFP Photo)

Members of the “Exit Point” amateur rope-jumping group stage a performance as they jump from a 44-metre high (144-ft) waterpipe bridge in the Siberian Taiga area outside Krasnoyarsk, November 3, 2013. Fans of rope-jumping, a kind of extreme sport involving a jump from a high point using an advanced leverage system combining mountaineering and rope safety equipment, marked the end of the group's jumping season and recent Halloween festivities. (Photo by Ilya Naymushin/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)

Here's a vehicle for the one percent. Dubbed as “the world's most luxurious RV” the 40-foot-long EleMMent Palazzo costs a staggering $3million USD – or more depending on the client's personal choices. If the buyer wishes to add a “top of the range” Model D stereo system with “gold remote control” the cost will be bumped by around $200,000. A “home theatre” could add $60,000 but this time the gold remote will be another $6,000. (Photo by Splash News)

An AH-64D Apache attack helicopter flies in front of a wall of fire during the South Carolina National Guard Air and Ground Expo at McEntire Joint National Guard Base, South Carolina, U.S. on May 6, 2017. (Photo by Jorge Intriago/Reuters/Courtesy Air National Guard)

U.S. Army soldiers with the 1st Battalion, 501st Infantry Regiment deployed to Combat Outpost Sabari, Afghanistan scan their area as they begin a multi-day air assault mission near the Pakistani border of eastern Afghanistan's Khost province May 2, 2012. (Photo by Staff Sgt. Joshua L. DeMotts/U.S. Air Force)

Sandra, a 29-year-old orangutan at Buenos Aires' zoo, on May 20, 2015. Sandra got cleared to leave a Buenos Aires zoo that was her home for 20 years, after a court ruled she was entitled to more desirable living conditions. (Photo by Juan Mabromata/AFP Photo)

Bangladeshi people walk in a polluted air environment in Dhaka, Bangladesh on September 3, 2020. A study says, air pollution shortens life expectancy by seven years in Bangladesh. (Photo by Sultan Mahmud Mukut/SOPA Images/Rex Features/Shutterstock)