Solar Impulse, a solar airplane, landed safely on May 23 in Texas, completing the second and longest leg of an attempt to fly across the United States powered only by the sun. The solar airplane developers hope to eventually pilot it around the globe. A ground team of weather specialists, air traffic controllers and engineers track the plane's speed and battery levels and help the pilot steer clear of turbulence.    

However, Solar Impulse cannot fly in strong wind, fog, rain or clouds. Its machinery is not even designed to withstand moisture. The spindly experimental aircraft touched down at Dallas/Forth Worth International Airport shortly after 1 am, local time, logging 18 hours and 21 minutes in the air to cover 823 nautical miles (1,541 km) from Arizona.    

The flight set a new absolute world distance record in solar aviation, the organisers said. Solar Impulse, which flies at an average pace of just 43 miles per hour (69 km per hour), began its cross-country sojourn on May 3 with an 18-hour-plus flight from northern California to Phoenix. After additional stops in St Louis and Washington, DC, pausing at each destination to wait for favorable weather, the flight team hopes to conclude the plane's voyage at New York's John F Kennedy International Airport in early July.