From VOA Learning English, this is the Technology Report.
In 2012, a team of pilots and engineers from Switzerland successfully flew a plane powered by sunlight from Spain to Morocco. The same team carried out a long-distance flight in the western United States in 2013. Now the Swiss team is preparing for a flight around the world in 2015. The new, improved version of the plane, named Solar Impulse 2, was recently shown in Switzerland.
Solar Impulse 2 is a very light, single-seat airplane. It is 63 meters from the end of one wing to the end of the other. This large wingspan provides 200 square meters of space for energy cells that charge lithium-ion batteries. These special batteries are needed to keep the plane flying at night. Four electric motors permit the plane to cruise at a speed of up to 140 kilometers per hour at an average height of 8,500 meters above sea level.
The longest flight of Solar Impulse 1 was made in May 2013. The plane flew from Phoenix, Arizona to Dallas, Texas a distance of just over 1,500 kilometers.
Twelve years of research and testing went into building Solar Impulse 2. The researchers believe the aircraft will be able to fly around the world in 20 to 25 days and nights.
Bertrand Piccard is the chairman of the Solar Impulse project. He says the goal of the flight around the world is to support efforts toward energy efficiency.
Solar Impulse 2 began test flights in May. The team plans to start the flight around the world next March from an airport somewhere along the Persian Gulf.