Test Flight Planned With Launch Window Opening Thursday

The fourth powered flight of Virgin Galactic's VSS Unity spacecraft may take the test pilots to the fringe of space. And the window for that flight opens Thursday, December 13.

Space News reports that in a statement issued December 11, the company said that the next powered test flight of SpaceShipTwo will take place between December 13 and 15, if all goes according to current plans. "At a basic level, this flight will aim to fly higher and faster,” the statement said. “We plan to burn the rocket motor for longer than we ever have in flight before, but not to its full duration."

The goal of the mission is to collect new data points concerning the performance of the spacecraft. The length of the rocket burn will be determined by how well the spacecraft is performing. On its most recent powered test flight, the motor burned for 42 seconds, leaving about 18 seconds of fuel remaining. That flight reached a peak altitude of 52 kilometers, or just over 32 miles.

“At the end stages of the rocket burn in the thin air of the mesosphere and with the speeds that we expect to achieve, additional altitude is added rapidly,” the company stated.

Whether or not that is enough to reach "space" depends on how "space" is defined. “We also plan to burn the rocket motor for durations which will see our pilots and spaceship reach a space altitude for the first time.” But the company also hedged, saying that “it may take us a little longer to get to that milestone.” depending on how this flight goes.

NASA and the USAF generally define "space" as an altitude of 50 miles. Pilots and crew who cross that threshold are awarded astronaut wings. That is also the benchmark that will be used for Virgin Galactic pilots and passengers, according to company CEO George Whitesides. "I think we’ll be focused on 50 miles, at least at the start," he reportedly said last month.

But that is below the 100-kilometer (62 miles) "Kaman Line" that has been recognized as the boundary for space by other entities, including the Fédération Aéronautique Internationale (FAI), and used for awarding the Ansari X Prize to SpaceShipOne in 2004. However, FAI said November 30 that it was considering lowering that threshold, according to the report.

In its statement, Virgin Galactic said that it would be carrying four unnamed payloads for NASA that would provide additional research as well as to start simulating the commercial weight distribution in the spaceship represented by our future passengers.”

(Images from file)

FMI: Source report