The balloons -- called HBAL199 and HBAL237 -- are more than 60,000 feet (18,000 meters) above land, according to FlightRadar24.com. They navigate using an algorithm that puts them in the best position to deliver signal by rising and falling to ride wind currents. They are also solar-powered and only provide signal during the day.
Several more balloons are on their way from Nevada, and Alphabet has been authorized by the Federal Communications Commission to send up to 30 balloons to serve the hard-hit area, according to Libby Leahy, spokeswoman for Alphabet's X, its division for futuristic technologies.
Project Loon head Alastair Westgarth said in a blog post that Project Loon is "still an experimental technology and we're not quite sure how well it will work," though it has been tested since last year in Peru following flooding there.
Hurricane Maria devastated the U.S. territory of 3.4 million people since making landfall last month. Gov. Ricardo Rossello said Friday the death toll had risen to 49. Less than a fifth of the island has electricity, half its cellphone towers are still not functioning, schools are closed and more than 4,000 are in shelters, according to a government website.
AT&T spokesman Jeffrey Kobs said the company has set up 14 temporary cell sites, and as of Friday more than 60 percent of the population was connected via mobile network, in part due to the help of humanitarian and government groups and Project Loon.
Other technology companies such as Cisco, Facebook and Tesla have also pledged help or have sent teams to the island to improve communications and restore power.
--The Associated Press