PAYERNE, Switzerland — An experimental solar-powered plane landed safely Thursday after completing its first 24-hour test flight, proving that the aircraft can collect enough energy from the sun during the day to stay aloft all night.
Pilot Andre Borschberg eased the Solar Impulse onto the runway at Payerne airfield about 30 miles southwest of the Swiss capital Bern at exactly 9 a.m. (3 a.m. EDT) Thursday.
Helpers rushed to stabilize the pioneering plane as it touched down, ensuring that its massive 207-foot wingspan didn't scrape the ground and topple the craft.
The record feat completes seven years of planning and brings the Swiss-led project one step closer to its goal of circling the globe using only energy from the sun.
"We achieved more than we wanted. Everybody is extremely happy," Borschberg told reporters after landing.
Previous flights included a brief "flea hop" and a longer airborne test earlier this year, but this week's attempt was described as a "milestone" by the team.
The team said it had now demonstrated that the single-seat plane can theoretically stay in the air indefinitely, recharging its depleted batteries using 12,000 solar cells and nothing but the rays of the sun during the day.
But while the team said this proves that emissions-free air travel is possible, it doesn't see solar technology replacing conventional jet propulsion any time soon.
Instead, the project's overarching purpose is to test and promote new energy-efficient technologies.
Project co-founder Bertrand Piccard, himself a record-breaking balloonist, said many people had been skeptical that renewable energy could ever be used to take a man into the air and keep him there.
"There is a before and after in terms of what people have to believe and understand about renewable energies," Piccard said, adding that the flight was proof new technologies can help break society's dependence on fossil fuels.
Global flight in 2013
The team will now set its sights on an Atlantic crossing, before attempting a round-the-world flight in 2013, making only five stops along the way.
"It's absolutely not time to relax," said Piccard.
Borschberg took off from Payerne airfield into the clear blue sky shortly before 7 a.m. Wednesday, allowing the plane to soak up plenty of sunshine and fly in gentle loops over the Jura mountains west of the Swiss Alps.
The custom-built aircraft with its thin fuselage and the wingspan of a Boeing 777 passenger jet managed to climb to 28,000 feet and reached top speeds of over 75 mph.
Borschberg, a 57-year-old former Swiss fighter who was wearing a parachute — just in case — dodged low-level turbulence and thermal winds, endured freezing conditions during the night and ended the test flight with a picture-perfect landing to cheers and whoops from hundreds of supports on the ground.
"The night is quite long, so to see the first rays of dawn and the sun returning in the morning — that was a gift," Borschberg said after touchdown.
Former NASA chief pilot Rogers E. Smith, one of the project's flight directors, praised Borschberg's feat of endurance and the overall success of the mission.
"We ended up with perhaps 20 percent more energy than we in the most optimistic way projected," Smith told The AP.
After completing final tests on the plane after landing, Borschberg embraced Piccard before gingerly unstrapping himself from the bathtub size cockpit he had spent more than 26 hours sitting in.
"When you took off it was another era," said Piccard, who achieved the first nonstop circumnavigation of the globe in a balloon, the Breitling Orbiter III, in 1999. "You land in a new era where people understand that with renewable energy you can do impossible things."
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