Once in place, the light but durable balloons wouldn't interfere with aviation because they fly twice as high as airplanes and well below satellites, said Richard DeVaul, an MIT-trained scientist who founded Project Loon and helped develop Google Glass, eyeglasses with a tiny, voice controlled computer display.
In the U.S., however, Google would have to notify the Federal Aviation Administration when the balloons are on their way up or down. The company is talking with regulators in other countries about meeting their requirements.
The Internet signals travel in the unlicensed spectrum, which means Google doesn't have to go through the onerous regulatory processes required for Internet providers using wireless communications networks or satellites.
At this stage, the company is putting a few dozen balloons up over New Zealand and then bringing them down after a short period. Later this year, Google hopes to have as many as 300 of them circling the globe continuously along the 40th parallel, on a path that takes them over New Zealand, Australia, Chile and Argentina.
Covering the whole world would require thousands of the balloons. No timetable has been set for that.
Google chose New Zealand in part because of its remoteness. Some Christchurch residents were cut off from the Internet for weeks after a 2011 earthquake that killed 185 people. Google said balloon access could help places suffering natural disasters get back online quickly.
"The potential of a system that can restore connectivity within hours of a crisis hitting is tremendously exciting," said Imogen Wall at the U.N. Office for the Coordination of Humanitarian Affairs, although she warned that the service must be robust. "If the service fails in a crisis, then lives are lost."
Temple University communications professor Patrick Murphy warned of mixed consequences, pointing to China and Brazil as places where Internet service promoted democratic principles but also contributed to a surge in consumerism that has resulted in environmental and health problems.
"The nutritional and medical information, farming techniques, democratic principles those are the wonderful parts of it," he said. "But you also have everyone wanting to drive a car, eat a steak, drink a Coke."
Already the world's largest advertising network, Google stands to expand its own empire by bringing the Internet to more corners of the Earth. More users means more potential Google searchers, which in turn translates into more chances for the company to display ads.
Richard Bennett, a fellow with the nonprofit Information Technology and Innovation Foundation, was skeptical of the project, noting that smartphones are increasingly being used in developing countries.
"I'm really glad that Google is doing this kind of speculative research," he said. "But it remains to be seen how practical any of these things are."
Before heading to New Zealand, Google spent a few months secretly launching two to five flights a week in California's Central Valley.
"People were calling in reports about UFOs," DeVaul said.
Mendoza reported from Mountain View, Calif. Follow Martha Mendoza at http://twitter.com/mendozamartha