At dawn on May 3, a one-of-a-kind electric plane called the Solar Impulse, fueled only by solar panels sealed into the skin of its 747-size wingspan, departed Silicon Valley for its first flight across America. The two-month journey – which includes stops in Phoenix, Dallas, St. Louis, and Washington, D.C., before reaching its final stop in New York in July – is a test run and fundraising campaign for the project's ultimate mission: the first sun-powered circumnavigation of the globe. The founders of the Solar Impulse company, Swiss adventurers Bertrand Piccard and André Borschberg, plan to make that flight in 2015, after constructing a larger, more high-performance plane. Borschberg, an ex-fighter pilot, is the project's chief engineer, while Piccard outlined the team's mission and pitched it to investors.

Piccard hails from a long line of explorers, and gained fame in 1999 as the first person to travel nonstop around the world via hot air balloon – a feat that ate up nearly four tons of propane. Stunned by that wastefulness, he vowed to make his next circumnavigation fuel-free.Rather than wait for the technology that would make such a trip possible, Piccard and Borschberg developed it themselves. "We calculated that we needed a plane with the wingspan of a jumbo jet and the weight of a small car," Piccard says. "All the airplane industry people said we were crazy, so we found people in other fields. The guy who built the hulls of the Alinghi boats for the America's Cup made our carbon fiber pieces." Fourteen years later, they've created a plane that, in theory, can fly forever. It climbs toward the sun during the day, electric motors driving its propellers. At night, it glides slowly down, burning the sunlight banked in its 882-pound batteries. The only limit to flight is a pilot's ability to stay awake. For Piccard, who flew the initial, ­19-hour leg of the trans-American flight, that was no challenge. "Piloting the Solar Impulse is like a meditation," he says. "You can't think about your arrival because the flight is very long. You must stay focused on the present moment, which is beautiful. It's a state of being I like very much."