Years of hard work and testing have finally paid off. The Solar Impulse, a plane powered solely by solar energy cells, successfully flew through day and night. It spent the early morning of July 7 slowly climbing to an altitude of 8,700 meters to charge its batteries. 4:40pm saw the Solar Impulse take a long controlled dive to 1.5km, then continued flying at through the night without depleting its power reserve.
The Solar Impulse weighs as much as a car (1,600 kg), yet has a wingspan of 208 ft. For comparison the wingspan of the Airbus A380—the largest passenger airliner in the world is 238.6 ft. Its array of 11,628 solar cells generated power for 400kg worth of batteries, which run 4-HP electric engines.
The team behind the solar-powered flyer are now working on another plane, designed to go around the world non-stop. Team estimates place the future flight within the 2012-2013 range. We're definitely a long way from solar-powered airliners, but it's clear that some headway is being made.