Dozens of companies are dotting the skies with satellites, part of a growing bet that buyers on Earth will pay billions of dollars for a more granular view of the planet. Not all of the companies are likely to make it, according to industry observers.

Investors are pouring money into remote-sensing companies, with BlackSky Technology Inc. and Spire Global Inc. merging with so-called special-purpose acquisition companies this year. Competitors including Planet Labs Inc., Satellogic and Terran Orbital Corp. also have struck...

Dozens of companies are dotting the skies with satellites, part of a growing bet that buyers on Earth will pay billions of dollars for a more granular view of the planet. Not all of the companies are likely to make it, according to industry observers.

Investors are pouring money into remote-sensing companies, with BlackSky Technology Inc. and Spire Global Inc. merging with so-called special-purpose acquisition companies this year. Competitors including Planet Labs Inc., Satellogic and Terran Orbital Corp. also have struck deals to go public by combining with SPACs, while other companies have raised money from venture-capital funds.

Space-data companies, which use satellites to snap photos of Earth, track radio signals and use radar to peer through clouds, raised $5.2 billion last year, up from $1.4 billion in 2015, according to data from PitchBook. Through Nov. 10, companies had raised another $4.5 billion.

Buyers of the companies’ products have included defense and other government agencies that tap the information to track troop movements and military projects. Remote-sensing companies are increasingly targeting commercial clients: Agriculture firm Corteva Inc. sells satellite-data applications that allow farmers to boost crop yields and ranchers to manage pasture land, executives said.

Space-data companies also have said they see opportunities to sell information to buyers such as insurers, which could use it to assess disaster risks for properties, and energy companies, which could use the data to monitor pipelines. Other clients could include governments and businesses looking to monitor pollution and track environmental commitments.

Over time, some investors and executives expect a smaller number of companies to establish themselves as the market takes shape and companies pursue acquisitions.

“You will see a handful of dominant, very large players, emerging in each category,” said James Bruegger, investment chief at Seraphim, an investment firm that has backed remote-sensing companies.

The remote-sensing market generated $2.6 billion in revenue in 2020, more than double compared with about a decade ago, according to data-provider BryceTech. More than 800 remote-sensing satellites, most controlled by commercial operators, now orbit the planet, up from 123 at the end of 2011, according to the firm, which has counted 25 companies in the sector.

Some companies are betting on technologies such as radar that can penetrate clouds and provide coverage at night, or so-called hyperspectral sensors that can track hundreds of bands on the electromagnetic spectrum.

Maxar Technologies Inc. and Airbus SE have more established remote-sensing businesses, and are among the companies with satellites that capture images of Earth.

“We think that there’s such a massive market opportunity,” said Will Marshall, co-founder and chief executive of Planet Labs. The company operates around 200 smaller satellites and can sell the data they collect or products Planet creates based on that information.

Planet Labs has predicted it will generate $693 million in revenue during its fiscal year that ends in early 2026, up from $113 million for the fiscal year ended Jan. 31.

Two companies that are also offering products based on satellite data recently have scaled back revenue expectations. BlackSky said this month that it expected to generate at most $34 million in revenue for 2021, down from the $40 million it predicted earlier. BlackSky CEO Brian O’Toole said a factor in the change was supply-chain issues that disrupted building satellites for outside customers.

In July, Spire Global said it anticipated generating $40 million to $42 million in revenue for the year, less than the $54 million it said it expected in a June investor presentation, mostly because of delays tied to certain contracts and completing several new deals. The company confirmed the lower forecast when it reported third-quarter results in November.

Chris Quilty,

a satellite-industry analyst who runs his own research and advisory firm called Quilty Analytics, said he didn’t think the revenue forecasts issued by some newer Earth-imagery companies, when taken together, are achievable. Most revenue generated in the sector today still comes from defense and intelligence agencies, he said.

“Those customers have limited ability to grow their budget, and the commercial market is relatively small and has never demonstrated the type of growth acceleration that is being targeted,” Mr. Quilty said.

Companies that have raised money by completing public listings now have more resources to pursue deals, said John Serafini, chief executive at HawkEye 360 Inc., a closely held company that uses satellites to track radio-frequency signals. HawkEye 360 recently raised $145 million, and Mr. Serafini said he was looking for acquisitions.

Emiliano Kargieman, chief executive of Satellogic, which said in a July presentation it planned to expand its satellite fleet from 13 as of last year to 300 by 2025, said he didn’t think companies would pursue such combinations for now because the overall size of the market is large. Over a longer period, mergers would make sense in part to gain efficiencies, he added.

Dan Jablonsky, chief executive at Maxar, said the company had forecast a smaller total market size for its unit that provides data from satellites and related products compared with those released by other remote-sensing companies. “If it turns out that the numbers are wildly bigger than we think they are or we’ve published, we think that’s great for us,” he said.

Mark Sirangelo, a longtime space-industry executive who is now a scholar in residence at the University of Colorado, said companies would find ways to turn space-derived data into valuable products as the market sorts itself out. “It’s relatively disjointed now, but it’s not going to stay that way,” he said.

Write to Micah Maidenberg at micah.maidenberg@wsj.com