WASHINGTON — Virgin Galactic said Dec. 16 it is supporting competing bids from Orbital Sciences Corp. and Sierra Nevada Corp. for a portion of the $200 million NASA intends to award in March under the second round of its Commercial Crew Development (CCDev 2) program.

Both Orbital and Sierra are developing winged spacecraft to launch atop expendable rockets to deliver astronauts to the international space station.

Virgin Galactic is currently flight testing SpaceShipTwo, a passenger-carrying suborbital spacecraft expected to launch into space for the first time in 2011.

“As a contributor to [Sierra Nevada’s] and [Orbital Sciences’] submissions to NASA, [Virgin Galactic] is proposing to market seats on these vehicles to the public and to its existing customer base, which now numbers more than 400 people who have made deposits of over $54 million,” Virgin Galactic said in a Dec. 16 news release.

The New Mexico-based firm also said it could potentially offer its WhiteKnightTwo carrier aircraft for use during the companies’ test flight programs.

Dulles, Va.-based Orbital Sciences Corp. said Dec. 14 that it is seeking NASA CCDev 2 funding for a “blended lifting body” vehicle that would launch atop an Atlas 5 rocket to deliver four astronauts to the international space station.

Sparks, Nev.-based Sierra Nevada Corp., which garnered $20 million in NASA’s first round of CCDev awards, would use CCDev 2 funds to mature its Dream Chaser orbital spacecraft, a six-passenger vehicle based on NASA’s HL-20 concept.

NASA kicked off the CCDev program in February 2010 by awarding $50 million in contracts to a mix of five new and established aerospace firms.