By Drew FitzGerald and Andy Pasztor

Amazon.com Inc.'s plan to spend more than $10 billion on a constellation of internet-beaming satellites has left industry insiders guessing about which customers the company plans to serve.

The e-commerce company's space venture won Federal Communications Commission approval last month to launch more than 3,200 low-Earth-orbit satellites over the next nine years. The proposed network, called Project Kuiper, takes a well-worn path pursued by rivals including billionaire Elon Musk's Space Exploration Technologies Corp., OneWeb and other companies that have tried to take satellite broadband service mainstream.

Those companies got a head start on Amazon, which has yet to launch a single satellite. Mr. Musk's company, known as SpaceX, has launched dozens of satellites this year. The closely held company has tapped the private market several times to fund its rocket business and the new communications network, called Starlink. SpaceX and Amazon both promise their technology can provide more internet bandwidth at a lower price than existing satellite operators.

"Technologically, it can be done," said Gabriel Rebeiz, a wireless-communications professor at the University of California, San Diego. "It's really a financial thing. Once you build it, is it economically viable?"

Amazon is under less pressure than other satellite companies to show investors its service will turn a quick profit. The Seattle company, which generated nearly $90 billion in revenue last quarter, said in a blog post last month that it plans to steer more than $10 billion toward Kuiper over the coming years as it posts hundreds of jobs for the unit.

Amazon told regulators its satellites could help bridge the digital divide by bringing high-speed broadband to areas that lack competitive internet service. Amazon spokesman James Watkins declined to specify the company's expected customer base but confirmed that the network will serve households as well as businesses.

The company promised in its FCC application to "leverage its considerable engineering resources, global operational capabilities and cost-conscious approach" to give customers "an affordable, high-quality broadband experience."

Amazon isn't the first big tech company to try bypassing traditional internet providers. Google owner Alphabet Inc. and Facebook Inc. have launched projects that deliver connections over fiber-optic cables, solar-powered drones and lighter-than-air balloons, with mixed success on a small scale.

Some industry officials say the Kuiper effort comes with significant technical hurdles, high costs of deploying so many satellites and a steep drop-off in potential markets because of the coronavirus pandemic.

Project Kuiper is designed to cut latency -- the time it takes for the machines to communicate back and forth -- by maintaining an Earth-hugging orbit that circles the globe much more quickly than other satellites. That close-to-home real estate forces the system to maintain thousands of satellites to ensure customers on the ground are constantly in range.

The FCC approval followed the bankruptcy of OneWeb Global Ltd., widely seen as one of the leaders in seeking to provide global internet connectivity through a constellation of satellites. Financed largely by Japan's SoftBank Group Corp. and European aerospace giant Airbus SE, OneWeb succeeded in mass-producing small satellites faster and cheaper than any company before. Still, the business plan suffered as its overall project costs surged and the development of inexpensive ground equipment faltered.

Months before its bankruptcy, OneWeb jettisoned its initial concept of pursuing consumers and small businesses in developing regions in favor of serving cruise-line, aviation and other established markets able to pay higher service fees.

Those potential markets are now reeling from the pandemic. Veteran space-industry consultant Roger Rusch, who has criticized low-orbiting constellations as exceedingly expensive to deploy and typically in need of replacement within a few years, said Amazon's project appears to take an approach similar to earlier efforts by committing to huge upfront investments before revenue starts to flow.

"I haven't seen anything that differentiates it," he said. In the past, he added, proponents of such projects "got into trouble because they didn't fully understand the magnitude of what they were trying to do."

Amazon Chief Executive Jeff Bezos personally owns a rocket company, Blue Origin Federation LLC, which could help keep a lid on launch costs. Mr. Watkins said the company is considering all options for launch services.

Steve Collar, chief executive of Luxembourg-based satellite service provider SES SA, said the "eye-watering" cost of launching orbiters and making new home receivers will probably limit the profitability of low-Earth-orbit satellites outside the U.S.

"Jeff Bezos, I'm sure, has a business plan," Mr. Collar said in an interview. "But you certainly need to have a very long time horizon. Because $10 billion isn't where it stops."

Mr. Collar previously led O3b, another satellite company founded to connect the Earth's three billion people without access to true broadband. High costs led the company to focus on a smaller customer market before it merged with SES.

SpaceX's satellite-internet service has struggled with delays and high costs. The broadband service had initially planned to go online as early as 2018, according to internal documents previously viewed by The Wall Street Journal. A SpaceX spokesman declined to comment.

Project Kuiper has so far only secured U.S. approval for its satellite network and will need other regulators' assent before it can provide service in more countries. The system's design would cover most of the U.S. except for parts of Alaska.

Some telecom industry insiders assumed Amazon would use its satellites to connect far-flung data centers and offer fat data pipes to major customers in the corporate world and government sector. Prof. Rebeiz said Project Kuiper, like other satellite companies, will probably sell a large amount of its network capacity to military clients. Amazon's cloud-computing division already holds a unit devoted to serving data-center resources for military and aerospace clients.

Viasat Inc. Chief Executive Mark Dankberg said his company, which serves about 600,000 broadband customers from satellites stationed at higher orbits, offers the best model for consumers demanding more data capacity above all else. He said Amazon's low-latency connections will appeal more to businesses.

"Amazon can fund whatever they want in this," Mr. Dankberg said at a recent investor conference hosted online. "On the other hand, they also tend to be pretty rational. They don't waste capital. So I don't think they will underprice bandwidth that they bring to market."

Write to Drew FitzGerald at andrew.fitzgerald@wsj.com and Andy Pasztor at andy.pasztor@wsj.com