Virgin Galactic founder Richard Branson and pilot Kelly Latimer stand next to the 747-400 airplane that would be used to air launch the company's rocket. (Virgin Galactic)

The celebrity space tourists that Richard Branson’s Virgin Galactic plans to shoot into space in the coming years may get most of the attention. But over the past couple of years he’s been increasingly focused on another space venture — one that would launch small satellites into orbit.

Now Virgin Galactic officials have decided to break off the satellite launcher program and make it its own company. Called Virgin Orbit, the California-based firm is seeking to enter a market that has attracted a lot of interest in recent years as satellites, once huge and expensive, have shrunk in size and cost.

The new company is to be led by Dan Hart, who spent 34 years at Boeing, where he most recently ran its satellite programs.

In a statement, Branson said the new venture fits into his ethos of opening up the cosmos “by manufacturing vehicles of the future, enabling the small satellite revolution, and preparing commercial space flight for many more humans to reach space and see our home planet.”

In an interview in 2015, he said he “never even thought of satellites when we thought of Virgin Galactic originally. I just thought of human space travel and a personal desire to go to space and trying to make dreams come true and so on. And then embarking on that, suddenly you realize there’s another whole aspect to this. Which is equally as exciting, really.”

Virgin Orbit would join a growing number of companies developing rockets designed specifically for carrying smaller payloads into space.

And it comes as a number of companies have proposed putting up large constellations of small satellites — some the size of a shoe box — that could serve a wide array of purposes, including monitoring crop yields, taking images of Earth, and providing Internet and communications.

Backed by a $1 billion investment from Google and Fidelity, Elon Musk's SpaceX has announced plans to launch nearly 4,500 satellites that would beam Internet service to Earth. Boeing has a similar plan, as does a London-based company called OneWeb.

SoftBank, the Tokyo-based telecommunications firm, recently announced that it is investing $1.7 billion to merge OneWeb with Intelsat.

As interest grows in the new generation of satellites, many companies are sensing an opportunity. Vector, founded by a pair of entrepreneurs who were involved in the early days of SpaceX, is developing a new rocket designed for smaller payloads. As is Rocket Labs, which is based in New Zealand and California.

Carissa Christensen, the chief executive of consultancy for Bryce Space and Technology (formerly known as Tauri Group Space and Technology), said there are about three dozen small satellite launch vehicles at various stages of development — likely resulting in winners and losers.

“The market cannot support that many vehicles,” she said. “There’s going to be a shakeout.”

Failed ventures, however, are not “indicative of a broken system,” she said. Much of the initial start-up money for these small satellite companies is coming from venture capital firms that “are generally risk tolerant. So you get starts and stops. You get companies that try and fail,” she said.

Virgin Orbit may begin with an advantage. It already has several commercial and government customers signed up, said George Whitesides, who oversees Virgin’s commercial space portfolio. It operates in a 180,000-square-foot manufacturing site in Long Beach, Calif., with 200 employees.

The company plans to “air launch” its two-stage rocket — meaning it would be tethered under the wing of a 747 airplane that Branson dubbed “Cosmic Girl” and that would fly to an altitude of 35,000 feet or so. The rocket would be released and then shoot off to space.

Whitesides said that the company would “launch when we’re ready” but that it hopes to complete a test flight by the end of the year.

Virgin Galactic also air launches its spaceplane, SpaceShipTwo, which is designed to fly two pilots and six passengers into space. The latest version of the spacecraft had its third successful test flight when it was released from its mother ship last week. It then glided back down to Earth without firing its engines.