MOJAVE, Calif. — A nine-month pause in powered test flights of Virgin Galactic’s SpaceShipTwo suborbital vehicle will end “imminently” as the company plans to take official possession of the vehicle and receive its launch license, company officials said Oct. 4.

“Those are going to start imminently, literally very imminently,” said Mike Moses, vice president of operations of Virgin Galactic, during a media tour of the company’s Final Assembly, Integration and Test Hangar (FAITH) here, where SpaceShipTwo and its carrier aircraft, WhiteKnightTwo, are built.

SpaceShipTwo made its last powered test flight Jan. 10. In May, the company announced it was switching the fuel used in the vehicle’s hybrid rocket motor, hydroxyl-terminated polybutadiene, a form of rubber, to a polyamide-based plastic.

Virgin Galactic has tested that new motor in a series of developmental and qualification, or “qual,” tests on the ground, but has not yet flown it on SpaceShipTwo. “We have now one more formal qual in our program of qual fires of the plastic motor,” Virgin Galactic Chief Executive George Whitesides said. If that test is successful, he said, the engine would be ready for flight on SpaceShipTwo.

Previous test flights of SpaceShipTwo have been the responsibility of Scaled Composites, which developed the vehicle under contract with Virgin Galactic. Those flights have used an experimental permit issued by the U.S. Federal Aviation Administration in 2012.

“We have a few more development test flights that will be run by Scaled,” Whitesides said. “We’ll then pass the vehicles over to Virgin Galactic, at which point we will request that the FAA make a determination and issue our license.”

The timing of that handover from Scaled Composites to Virgin Galactic will depend on the progress on the upcoming test flights, which Whitesides said could include a full suborbital flight. “What we’d like as a minimum is for them to demonstrate supersonic re-entry and peak heating,” he said of Scaled. The two companies have already been working together on flight operations, and Virgin Galactic took over WhiteKnightTwo earlier in the year.

Complicating the transition from Scaled to Virgin is current federal law, which does not allow a vehicle to hold both an experimental permit and a launch license simultaneously. Virgin Galactic submitted an application for a launch license for SpaceShipTwo in the summer of 2013, which the FAA declared to be “sufficiently complete” in August 2013, starting a 180-day review period.

Whitesides said Virgin Galactic asked the FAA to place a “voluntary toll” on the application early this year, with less than a month left in the review period, to prevent the FAA from issuing the license and thus invalidating the experimental permit before Scaled and Virgin were ready to transition operations. “When Scaled and us  — and frankly the FAA — feel like we’re ready for this big transfer, we will request that the toll be removed,” he said.

Once Virgin Galactic has the launch license, Whitesides said, it will perform several test flights, including some at Spaceport America in New Mexico, before beginning commercial service. Whitesides declined to provide a specific schedule for those milestones but Sir Richard Branson, Virgin Galactic’s founder, said in televised interviews in September that he expected to fly on the first commercial SpaceShipTwo flight in February or March of 2015.

The Virgin Galactic media event was tied to the 10th anniversary of the final flight of SpaceShipTwo’s predecessor, SpaceShipOne, at the Mojave Air and Space Port. That flight won the $10 million Ansari X Prize for Mojave Aerospace Ventures, a joint venture of Scaled Composites and Microsoft co-founder Paul Allen, who funded SpaceShipOne’s development.

At a luncheon commemorating the anniversary here Oct. 4, Branson said SpaceShipTwo was about to begin commercial flights, but acknowledged the several years of delays the program has experienced.

“We’re on the verge,” Branson said in a panel session during the luncheon. “We’re going to start soon, as I’ve been saying for a few years.”

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...