Two scientists will attempt to fly across the US using a solar-powered plane.
The Solar Impulse is the brainchild of a pair of Swiss aviators and engineers, Bertrand Piccard and Andre Borschberg.
It consists of a giant wingspan the size of a Boeing 747, covered with 12,000 ultra-thin solar cells, a battery for power storage and a tiny cockpit with room for one pilot.
Solar Impulse is about the size of a compact car and has a maximum speed of only 56km per hour (kmph). But it is part of a bid to inspire people to use alternative energy.
Al Jazeera's Rob Reynolds reports from Mountain View, California.