Solar Impulse is a Swiss long-range experimental solar-powered aircraft project, and also the name of the project's two operational aircraft.[1] The privately financed project is led by Swiss engineer and businessman André Borschberg and Swiss psychiatrist and aeronaut Bertrand Piccard, who co-piloted Breitling Orbiter 3, the first balloon to circle the world non-stop.[2] The Solar Impulse project intends to achieve the first circumnavigation of the Earth by a piloted fixed-wing air rcraft using only solar power. The aircraft are single-seat monoplanes powered by photovoltaic cells and capable of taking off under their own power. The prototype, often referred to as Solar Impulse 1, was designed to remain airborne up to 36 hours.[3] It conducted its first test flight in December 2009. In July 2010, it flew an entire diurnal solar cycle, including nearly nine hours of night flying, in a 26-hour flight.[4] Piccard and Borschberg completed successful solar-powered flights from Switzerland to Spain and then Morocco in 2012,[5] and conducted a multi-stage flight across the United States in 2013.[6][7] A second aircraft, completed in 2014 and named Solar Impulse 2, carries more solar cells and more powerful motors, among other improvements. In March 2015, Piccard and Borschberg began an attempt to circumnavigate the globe with Solar Impulse 2, departing from Abu Dhabi in the United Arab Emirates.[8] The aircraft was scheduled to return to Abu Dhabi in August 2015, upon the completion of its multi-stage journey.[9] By 1 June 2015, the plane had traversed Asia.[10] On 3 July 2015, the plane completed the longest leg of its journey, from Japan to Hawaii.[11] During that leg, however, the aircraft's batteries experienced thermal damage that is expected to take months to repair. The Solar Impulse team stated that they hope to resume the circumnavigation in April 2016.[12] less