TULSA, OK - MAY 21: Solar Impulse 2, the solar airplane of Swiss pioneers Bertrand Piccard and André Borschberg, in preparation for the take off from Tulsa International Airport, Oklahoma, with André Borschberg at the controls, on 21 May at 4:22am local time (UTC-5). The plane, which is piloted by Borschberg, is expected to land at Dayton International Airport, Ohio, on the same day at around 11:00pm local time (UTC-4). The flight is part of the attempt to achieve the first ever Round-The-World Solar Flight, the goal of which is to demonstrate how modern clean technologies can achieve the impossible. Christophe Chammartin/ SI2
