A unique airplane has just completed a 4,000-mile journey, making the first solar-powered intercontinental round-trip air journey. Traveling between Europe and Africa, the Solar Impulse experimental solar airplane landed in Payerne, Switzerland at 8:30 p.m. local time (2:30 p.m. ET) on Tuesday. The odyssey began two months ago, on May 24. This wasn\'t a test to see how fast the plane could make the trip, but to assess its endurance and reliability. The project was also aimed at raising public awareness about energy issues. \"The goal of this airplane is not just to go from one point to another, but to fly as long as we wish, promote renewable energy and ambitious energy policies,\" pilot Bertrand Piccard, founder of Solar Impulse, said during the intercontinental flight. \"All of these have been so successful.\" Total flight time for Tuesday\'s 382-mile (615-kilometer) trip from Toulouse, France, to Payerne was 13 hours and 29 minutes. The average air speed was 28 mph (46 kilometers per hour). Solar Impulse flew the eight-leg, 4,000-mile (6,000-kilometer) trip from Payerne to Morocco and back again with Piccard and André Borschberg taking turns in the single-seat cockpit. Stopovers included Madrid in Spain, and Rabat and Ouarzazate in Morocco, as well as Toulouse. The most challenging destination, not only for this aircraft but for commercial ones as well, was Ouarzazate, a region rich in turbulence and strong winds. The plane flew during the day but often took off and landed at night to avoid areas of air turbulence called thermals. However, it was almost always brought back to the hangar with a full set of batteries, according to the team at Solar Impulse. Originally built only to prove the possibility of flying day and night on solar power (it flew a 26-hour flight in 2010), the prototype airplane is now in the process of collecting a number of distance world records for solar aircraft, such as straight distance, free distance and distance along a course. \"It’s been an extraordinary adventure, not only for what we’ve achieved with this airplane, originally only designed to demonstrate the possibility of flying day and night with a purely solar energy, but also for what has resulted in a tightly fused team, confident in the project and in their capacity to make it happen,” said Borschberg, who is Solar Impulse\'s CEO. \"I am proud what we’ve been able to accomplish together, all of us, from the engineers that have built a fantastic airplane, to the mission team experts that found a safe but successful strategy, to the ground crew who had to operate in challenging conditions and themultimedia team who under any circumstance brought the message of the project to the public.\" The flight was scheduled in conjunction with events in Morocco that promoted investment in innovative projects for job creation and sustainable growth while also decreasing dependency on fossil fuels. “The success of this mission was not only aeronautical: It also stands in the quantity of positive emotions we managed to bring to the cause of renewable energies,\" Piccard said at the end of Tuesday\'s flight. From : MSNBC.com