PICS:Solar plane to cross Pacific in 5 days, 5 nights

"It's the most challenging, yes, in the sense that we never flew over the oceans," Borschberg said in a phone interview from Nanjing. "There are of course also question marks with the type of airplane we have, is it capable to fly solo with this type of energy, and of course the challenge is on the pilot side as well ... can I stay alert for this leg and be able to pilot this airplane, can I keep my energy at the right level, can I keep my spirits, my mindset to get this airplane to Hawaii."