Doubts are growing about one of the first and most high-profile efforts by Google owner Alphabet to show that it can be more than an advertising cash machine.

Loon, a decadelong project to provide internet to rural areas and islands around the world using high-altitude helium balloons, earned the company years of fawning coverage in the press and photo-ops with government and telecom officials eager for the balloons to float over their lands. But after Loon spent all of the cash it raised from an external investor last year, Alphabet has had to float money for the project’s operations while it searched for new investors, said two people with direct knowledge of the situation. Like so many other Alphabet subsidiaries not related to online ads, Loon just didn’t turn into much of a business.