The solar-powered Solar Impulse is another leg closer to completing its mission across America.
Flown by Solar Impulse co-founder and Chairman Bertrand Piccard, the plane landed smoothly at Lambert-St. Louis International Airport at 1:28 a.m. local time Tuesday.
Taking to the skies on Monday morning from Dallas/Fort Worth International Airport, Piccard -- and the plane -- stayed in the air for 21 hours and 21 minutes, marking his longest flight to date.
The landing in St. Louis also saw the debut of an inflatable mobile hangar, which will be the aircraft's home until it takes off again. The inflatable hangar was designed for Solar Impulse's 2015 flight around the world but was called into duty Tuesday after a storm heavily damaged the hangar initially reserved for the plane.
"We brought the inflatable hangar to the USA for testing purposes and in fact it allowed the mission to stay on schedule," Solar Impulse co-founder and CEO Andre Borschberg said in a statement. "This exercise is now a proof of concept: rather than taking the airplane to a hangar, we have taken the hangar to the airplane."
Borschberg and Piccard are taking turns flying legs of the trip. The first leg, which began May 3, started from NASA's Moffett Field in the San Francisco Bay Area and ended in Phoenix. The second leg: a Phoenix-to-Dallas flight that began May 22.
The Solar Impulse team chose St. Louis as the third leg's destination because of its role in the world of aviation. Before he became famous, Charles Lindbergh flew a U.S. mail route from Chicago to St. Louis. Business leaders of the city supported Lindbergh's 1927 flight between New York and Paris, prompting his plane to be christened "The Spirit of St. Louis."
"It was particularly important for me to come to St. Louis because I was so inspired when I met Charles Lindbergh at Cape Canaveral during a launch of the Apollo when I was 11 years old," Piccard said in a statement. "I'm truly moved to be able to land here today with Solar Impulse."
The goal behind Solar Impulse is to prove the viability of clean energy. The 12,000 solar cells built into the wing use the sun's rays to charge the batteries that enable the plane to fly at night. The fourth leg of the flight will see the plane land in Washington, D.C., this month, while the fifth and final leg will end at JFK Airport in New York by early July.
Correction at 7:30 a.m. PT: The initial site for the journey has been fixed.