WASHINGTON — Virgin Galactic now plans to perform the first commercial flights of its SpaceShipTwo suborbital vehicle early next year, the latest schedule slip for the long-delayed program, the company’s founder said in a pair of televised interviews.

“From now until March there will be many test flights,” said Sir Richard Branson in an interview on CBS’s “The Late Show” Sept. 9. He said he planned to be on the first commercial flight, from Spaceport America in New Mexico, in “February or March of next year.”

In a separate interview on NBC’s “Today” show Sept. 9, Branson provided a similar schedule. “We’re now going through the final testing stages. We’ll be doing at least one flight into space before the end of the year,” he said. “I’ll be going up with my son Sam ‘early-ish’ in the new year.”

That timeline represents a delay from statements Branson made as recently as August. In an interview with USA Today published Aug. 17, he said he expected to be on that first commercial flight by the end of this year. “I’ll be bitterly disappointed if I’m not into space by the end of the year,” he said.

A Virgin Galactic spokeswoman said that despite Branson’s comments, the company has no formal schedule for beginning commercial flights. “As we’ve stated in the past, the inaugural commercial flight date will be set by safety and readiness,” Jessica Gilbert said Sept. 11 via email.

“We look forward to demonstrating spaceflight later this year in Mojave and bringing the vehicle to New Mexico soon after that to begin commercial service,” she added.

Virgin Galactic has ramped up SpaceShipTwo testing after a lull for much of 2014. On Aug. 28, the company performed an unpowered test flight of SpaceShipTwo, where it was released from its WhiteKnightTwo carrier aircraft and glided back to a runway landing at California’s Mojave Air and Space Port.

That flight featured a “cold flow” test of the spacecraft’s rocket engine, running liquid oxidizer through the motor without igniting it, a prelude for resuming powered test flights. In an Aug. 28 tweet, the company called that test flight “a great dress rehearsal for our next powered flight, which is coming soon.”

SpaceShipTwo’s last powered test flight was Jan. 10. In May, Virgin Galactic announced it was changing the solid fuel used in the vehicle’s hybrid rocket motor from hydroxyl-terminated polybutadiene, a form of rubber, to a polyamide-based plastic. That new fuel has been used in ground tests of the engine, but has not yet been fired in flight.

On Sept. 10, Virgin Galactic flew WhiteKnightTwo, without SpaceShipTwo, from Mojave to Spaceport America. The aircraft will fly “trial mission profiles” there as part of the overall flight test program, Gilbert said.

Development of SpaceShipTwo has suffered from a number of delays. When Branson first announced Virgin Galactic in a September 2004 press conference in London, plans called for commercial flights to begin as soon as late 2007.

“Fortunately it’s now going very well,” Branson said of the test program in his NBC interview. “It’s taken longer than we thought.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...