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In 1999, Bertrand Piccard traveled around the world in a balloon, without stopping a single time. Now, he's embarking on a journey across the United States — from San Francisco to New York — in an airplane with infinite gas mileage. The Solar Impulse HB-SIA is an electric aircraft powered entirely by solar panels, with 11,628 monocrystallane solar cells spread across its enormous Boeing 747-sized wing. Batteries, charged by those solar panels, take over in the evening.

On Friday, the craft began the first leg of its US voyage, from Mountain View, CA, to Phoenix, AZ — a 19-hour trip in the lightweight single-seater aircraft. One day at a time, with long breaks inbetween, the airplane will take two more months to reach its final destination in New York City. You can track the flight live.

Last year, the Solar Impulse flew from Europe to Africa in its first intercontinental flight, and the craft had its first international flight in 2011, but today the Swiss company's cofounder and chairman is showing the United States what solar power can do. The vision: an aircraft that can fly indefinitely without consuming any fuel whatsoever. This morning, we traveled to Moffett Field to witness the occasion.

Grid View At the crack of dawn, journalists and cameramen hungrily gather around the Solar Impulse HB-SIA, an airplane that doesn't use a single drop of fuel.

Before them, a runway beckons: Moffett Field, a former naval air station located in the heart of Silicon Valley. The iconic blimp hanger is undergoing restoration. Normally, its steel lattice is covered with panels.

The solar plane is practically all wing and tail, with only a tiny fuselage connecting the two. Four 10-horsepower electric engines propel the craft at just 43 miles per hour. "Our priority is not the speed, but the duration," says Piccard.

Pilots (and co-founders) Bertrand Piccard and Andre Borschberg excitedly discuss the voyage. "Today, we're starting a trip that's quite mythical in the history of aviation... flying coast to coast... it's one of the milestones."

The first leg of the journey will take 20 hours, says Piccard, "but 10 years I've been dreaming of this flight." He flew the first non-stop balloon trip around the world in 1999.

The airplane's cockpit boasts a solar-powered oxygen system, an electrocardiogram to monitor the pilot's fatigue level, a live video camera connected to the internet, "very compact energy bottles" for nutrition, and a seat with an integrated parachute and life raft.

The Solar Impulse only seats one. Though Borscheberg seemed nervous during the press conference, he cracks a big smile and shares some laughs as his partner is strapped into the cockpit.

An electric bicycle, which rode alongside the aircraft as it took off.

Piccard completes pre-flight checks, some thirty minutes before takeoff.

Fifteen minutes before takeoff, the Solar Impulse team attaches the cockpit canopy and begins clearing ladders and supports.

The Solar Impulse weighs just 3,527 pounds, but it has a wingspan of 208 feet — as wide as a Boeing 747. That wing generates so much lift that the plane can take off at 27 MPH with just a few hundred feet of runway.

At 6:12AM PT, the Solar Impulse gently, quietly lifts off the tarmac.



