A solar-powered aircraft which one day hopes to circle the globe has started a 24-hour test flight in Switzerland.
Solar Impulse took off shortly before 5 am GMT, Wednesday from an airfield in Payerne, 80 miles northeast of Geneva.
The plane is being piloted by Andre Borschberg who will fly the plane to a height of nearly 28,000 feet (8,500 meters) throughout the day.
During the evening the plane will slowly descend to an altitude of 5,000 feet (1,500 meters) where it will remain for the rest of the night, before Borschberg attempts a dawn landing.
Solar Impulse has a wingspan of over 63 meters -- the same as an Airbus A340 -- and is nearly 22 meters long. It weighs 1,600 kilograms and has nearly 12,000 solar cells attached to its wings and horizontal stabilizers.
The plane is also equipped with four electric engines and has a top speed of 70 kilometers per hour.
"The goal of the project is to have a solar-powered plane flying day and night without fuel," co-founder of the project, Bertrand Piccard said.
The Swiss adventurer, who piloted the first non-stop balloon flight around the world in 1999 in the Breitling Orbiter III said the test flight was "crucial for the credibility of the project."
The challenge to fly a solar plane around the world was officially announced in 2003.
If the 24-hour flight is successful, a second airplane will be designed to fly much further next year, with the aim of flying across continents and the Atlantic Ocean.
In 2012, the team hope to fly Solar Impulse around the world in five stages.