http://www.theguardian.com/technology/2015/jul/31/facebook-finishes-aquila-solar-powered-internet-drone-with-span-of-a-boeing-737#img-1

Because the planes must constantly move to stay aloft they would
circle a two-mile (3km) radius, Parikh said. During the day they would float to
90,000ft and at night drift down to 60,000ft to conserve energy.

http://www.forbes.com/sites/marcochiappetta/2015/07/31/facebooks-aquila-aircraft-which-can-beam-data-at-10gbs-using-laser-beams-is-complete/

In addition to designing and building the solar powered,
lightweight aircraft, Facebook also pioneered some interesting laser
communication technology. Also from the post, “We’ve successfully tested a new
laser that can transmit data at 10 gigabits per second. That’s ten times faster
than any previous system, and it can accurately connect with a point the size of
a dime from more than 10 miles away.” Transmitting data with lasers is nothing
new. But achieving those kinds of speeds, within a low-power envelope, while
airborne is impressive.