Yesterday, Solar Impulse safely touched down at Lehigh Valley International Airport in Pennsylvania. That's another 1000km ticked off of its bid to circumnavigate the globe using only solar energy. Image: Solar Impulse
The flight took almost 17 hours, with the aeroplane achieving an average speed of just 63km per hour. That's slow going, even for Solar Impulse -- but in strong head winds, the aircraft occasionally generates only enough power to stop itself from travelling backwards. The aeroplane uses 17,000 solar panels on its wings to charge 942kg of lithium battery, so there's a lot of weight to carry, hence the slow speeds.
The next flight leg on the round-the-world trip will see Solar Impulse head towards New York City. From there, it will cross the Atlantic to either Europe or North Africa, then finally head for Abu Dhabi, where the attempt started.