On March 9, 2015, Solar Impulse 2 lifted from the warm tarmac of Abu Dhabi, its 72-meter wingspan draped with 17,000 photovoltaic cells. The mission: to circle the globe without a drop of fuel. Behind the controls were two Swiss pioneers—Bertrand Piccard and André Borschberg—who had spent thirteen years proving that clean technologies could achieve the impossible. The aircraft was a flying laboratory: a carbon-fiber frame lighter than a family car, four electric motors, and lithium-polymer batteries that stored sunlight for night flight. The seventeen-stage journey spanned four continents, three seas, and two oceans. The decisive moment came in July 2015, when Borschberg took off from Nagoya, Japan, and spent 117 hours and 52 minutes—nearly five days and nights—aloft over the Pacific to Hawaii, setting the absolute world record for longest uninterrupted solo flight. Battery damage on that leg forced a ten-month layover for repairs, but the team returned in 2016. On July 26, 2016, Piccard landed back at Abu Dhabi after 42,000 kilometers and 555 flight hours. The journey had taken seventeen months and claimed nineteen FAI world records. What Solar Impulse proved was not merely that a solar airplane could fly, but that a renewable-energy future could take wing.