A new upgraded Swiss-made solar aircraft is poised to take the first round-the-world solar flight, without any fuel, in 2015, the team has announced. The Solar Impulse 2, launched by Swiss explorer Bertrand Piccard and Andre Borschberg, is the upgraded version of Solar Impulse 1, which is the first solar plane capable of flying day and night, crossing two continents and flying over the United Sates without fuel. The global flight is scheduled to start in March 2015 form the Gulf area. The single-seat aircraft will fly, in order, over the Arabian Sea, India, Burma, China, the Pacific Ocean, the United States, the Atlantic Ocean and Southern Europe or North Africa before closing the loop by returning to the departure point. The Solar Impulse 2, made of carbon fiber, has a 72 meter wingspan, which is longer than that of Boeing 747 jumbo jet. In addition, the aircraft only weighs 2,300 kg, equipped with as many as 17,000 solar cells to power four electric motors with renewable energy. During the day, the solar cells recharge lithium batteries to allow the aircraft to fly at night. Test flights are due to take place in May, followed by training flights over Switzerland.