Swiss pioneers Borschberg and Piccard celebrate completing the first leg of the Solar Impulse flight across the United States after arriving in Phoenix

 
Swiss pioneers Borschberg and Piccard celebrate completing the first leg of the Solar Impulse flight across the United States after arriving in Phoenix
Swiss pioneers Andre Borschberg (L) and Bertrand Piccard celebrate completing the first leg of the Solar Impulse flight across the United States after arriving in Phoenix May 4, 2013. The trip is an attempt to fly across the United States with no fuel but the sun's energy. Fred Merz/Solar Impulse/Handout via REUTERS