Have Sun, Will Travel

Their CVs combined look like the envy of all bona fide air adventurers. Pioneering ultralight aircraft? Been there. Setting world records by circling the globe nonstop in a balloon? Done that. Commanding the first ever 24-hour flight on a plane powered just by the sun? Yep, you've guessed it. And now, following 12 years of complex designs and intense training, aviation pioneers Bertrand Piccard and Andre Borschberg are set to conquer new heights, taking up the challenge of the first solar flight around the globe. The Swiss duo unveiled last week Solar Impulse 2, a revolutionary aircraft designed to achieve the longest ever flight in the history of aviation in terms of duration for a single pilot. It will attempt to fly non-stop for 120 hours (yes, that's five successive days and nights) over oceans and continents without a drop of fuel. Made of carbon fiber, Solar Impulse 2 is the evolution of a prototype that has smashed several aviation records in recent years, including the first fully solar-powered overnight flight lasting 26 hours in 2010. The upgraded plane has a huge wingspan of 72 meters (wider than a standard Boeing 747) and weighs only 2,300 kilos - that's about as heavy as a family car. Its wings are covered with a skin of 17,000 solar cells that supply four electric motors with renewable energy, while its custom-made lithium batteries are able to store enough solar energy throughout the day to keep the ultralight plane flying at night. So basically, what they have now is the first airplane in the world which has unlimited endurance. It can fly a day and a night, it can fly a week, it can fly a month - theoretically it can fly a year. And it can fly for such an extended period of time without a single drop of fuel. This begs the question: what will clean energy come up with next?