Google's Internet-beaming balloons

WHAT? The helium-filled balloons are made from a thin polyethylene film and are 15 meters (49 feet) in diameter when fully inflated.

Photo: A fully inflated test balloon sits in a hangar at Moffett Field airfield, Calif.

WHERE? They float in the stratosphere about 20 kilometers (12 miles) above the Earth.

Photo: A Google balloon sails through the air with the Southern Alps mountains in the background, in Tekapo, New Zealand.

HOW? The balloons would sail on the stratosphere's winds in a continuous circuit around the globe. The balloons come equipped with flight computers, and Google would control the balloons' altitude from the ground, keeping them moving along a desired channel by using different winds at different heights.

Photo: A Google team releases a balloon in Tekapo, New Zealand. Google is testing the balloons which sail in the stratosphere and beam the Internet to Earth.

A BREAKTHROUGH? Google says past attempts to control balloons have involved tethering them or using expensive motors to keep them in place. They say simply sailing with the winds was one of the company's breakthrough ideas.

Photo: Google's team at mission control monitors a balloon launch in Christchurch, New Zealand. Google is testing the balloons which sail in the stratosphere and beam the Internet to Earth.

THE ADVANTAGE? Google says the balloons have the potential to provide Internet access far more cheaply, quickly and widely than traditional underground fiber cables. One downside is that computer users on the ground would need to install a receiver to get the signal.

Photo: Tania Gilchrist stands outside her home below a red Google Internet receiver after agreeing to participate in Google's balloon testing program in Christchurch, New Zealand.

THE REACH? The transmitteron each balloon would beam down the Internet to an area about 1,250 square kilometers (780 square miles) - twice the size of New York City.

Photo: Jordan Miceli prepares electronics to launch balloons in Tekapo, New Zealand. Google is testing the balloons which sail in the stratosphere and beam the Internet to Earth.

THE CHALLENGE? Managing the flight of just one balloon in our complex and ever-changing atmosphere is a huge challenge. Trying to harmonize an entire fleet of thousands of them will be mind-boggling.

Photo: Solar panels and electronics are prepared for launch in Tekapo, New Zealand. Google is testing balloons which sail in the stratosphere and beam the Internet to Earth.