A Swiss-made, solar-powered airplane called Solar Impulse completed an 18-hour flight from San Francisco to Phoenix on Saturday, marking the first leg of a fuel-free odyssey across America.
Adventurer Bertrand Piccard piloted the craft, which has the wingspan of a jumbo jet but the weight of a typical passenger car, to its landing at Phoenix's Sky Harbor International Airport at 12:30 a.m. MST (3:30 a.m. EDT).
The flight went so smoothly that Piccard had to fly in circles for hours while he waited for the airport to shut down commercial flight operations as a safety precaution.
"It's a little bit like being in a dream," he told reporters after landing.
Piccard started out from Moffett Field in California's San Francisco Bay Area on Friday just after sunrise, a little more than 18 hours earlier. He could have driven the distance between the two cities in two-thirds that time – but that's not the point.
"A flying laboratory for clean technologies, this prototype is the result of seven years of intense work in the fields of materials science, energy management and man-machine interface," Andre Borschberg, Solar Impulse's co-founder and CEO, said before the flight.
Borschberg and Piccard are taking turns in the pilot's seat for a months-long series of flights that should end up in New York around the Fourth of July. Each leg of the odyssey is being monitored via streaming video, and the project is collecting thousands of names that will be added to a "Clean Generation" list of supporters carried in the cockpit.
Solar Impulse's power comes from its 12,000 photovoltaic cells, which soak up sunlight and store the electrical energy in batteries for use when the sun isn't shining. The plane generates as much power as a motor scooter for its four 10-horsepower motors. That's why the carbon-fiber craft has to be so big and light.
The "Across America" mission builds upon Piccard's experience as a record-setting, round-the-world balloonist, and draws upon financial backing from Swiss business concerns. In 2010, Solar Impulse took on the world's first solar-powered night flight, a 26-hour affair in Switzerland. The next year, it made the first international solar flight, from Switzerland to Belgium to France. And in 2012, it went on the first solar-powered intercontinental flight, from Europe to North Africa.
Borschberg told NBC News that flying across America poses a different set of challenges, due to the density of air traffic. "These places are very busy, so it's a learning experience," he said.
Over the next couple of months, Solar Impulse is due to fly from Phoenix to Dallas-Fort Worth, then to St. Louis, then Washington, then New York. As ambitious as this odyssey is, it's just a warm-up for the venture's ultimate goal: circumnavigating the world with solar power in 2015.
It may be a long time before solar-powered flight proves practical for passenger service. Borschberg said Solar Impulse's Swiss sponsors are more interested in the environmentally friendly technologies behind the project, ranging from more efficient solar power generation to lightweight carbon composite materials. "Their motivation is to develop products for applications on the ground," he told NBC News.