The creators of Solar Impulse - considered the world's most-advanced sun-powered plane - say their cross-country journey will mark a milestone in aviation history.
But more importantly, Bertrand Piccard and Andre Borschberg hope it will boost interest in the potential of renewable energy technology.
Piccard said Saturday there's so much people can do now to have a cleaner future.
Piccard is fresh off a 20-hour flight from San Francisco to Phoenix, marking the first leg of the trip across the U.S. in the solar airplane. Piccard landed the craft at Sky Harbor Airport at about 12:30 a.m., having used only three-quarters of the plane's battery power.
From Phoenix, the aircraft will travel to Dallas-Fort Worth airport in Texas, Lambert-St. Louis airport, Dulles airport in the Washington area and New York's John F. Kennedy airport. Each flight leg will take about 19 to 25 hours, with 10-day stops in each city.