The legendary Solar Impulse 2, an experimental aircraft that famously circled the globe in 2016 powered entirely by the sun, has been lost after crashing into the Gulf of Mexico. Once steered by Swiss aviators Bertrand Piccard and André Borschberg, the plane made aviation history by traveling 26,700 miles across four continents without a single drop of jet fuel. Since its retirement from record-setting manned travel, the craft had been acquired by Skydweller Aero, which reimagined the vessel as a high-altitude, solar-powered drone for military use.

The crash occurred on May 4, shortly after the drone departed from Stennis, Mississippi, for a series of testing exercises with the U.S. Navy. According to Skydweller Aero, the aircraft was intentionally guided into a "controlled ditching" following a successful eight-day mission that the company claims proves the long-term viability of solar-powered flight for defense operations. While the company celebrated the duration of the flight as a major milestone, the National Transportation Safety Board has launched a formal investigation into the circumstances surrounding the final descent.