Solar Impulse 2, an aircraft powered by solar energy, has left Egypt on the final leg of the first ever global fuel-free journey. Its flight to the United Arab Emirates was delayed due to a heat wave in Saudi Arabia.
The single-seat plane took off from Cairo today, en route to Abu Dhabi, its starting point in March 2015 and its final destination. The flight is expected to take between 48 and 72 hours.
Solar Impulse 2 arrived in Cairo after a two-day flight from Spain, finishing the 3,745-kilometer (2,327-mile) journey with an average speed of 76.7 kilometers per hour (47.7 miles per hour). On June 23, it became the first solar-powered aircraft to cross the Atlantic Ocean, flying 70 hours from New York to Seville, Spain.
The plane has been piloted in turns by Swiss aviators Andre Borschberg and Bertrand Piccard. The project is designed to build support for clean energy technologies.