LANCASTER, CALIFORNIA – Virgin Galactic scrubbed the Feb. 20 flight test for SpaceShipTwo, the air-launched suborbital spaceplane, due to high winds in Mojave, California. The flight test is now scheduled for Friday, Feb. 22.

“During our test flight program, we exercise a lot of caution around weather conditions,” George Whitesides, Virgin Galactic chief executive, told reporters during a Feb. 19 briefing. “If we see conditions we don’t like, we won’t fly.”

That was the case Feb. 20 with forecasts of winds in the 17 to 26 knot range and gusts above 34 knots.

“Upper level winds are not much of a concern for us,” Todd Ericson, Virgin Galactic safety and test vice president, told reporters during the briefing.

Crosswind during landing, though, are a concern.

As Virgin Galactic continues flight testing its second SpaceShipTwo, VSS Unity, it gradually exposes the spaceship to new challenges while carefully tracking its performance.

“In any test program I’ve been part of, crosswind envelope expansion is difficult,” said Ericson, former safety chief for the U.S. Air Force Flight Test Center and Air Force experimental test pilot. “You can’t twist the runway into the direction you want it to go. You have to take what Mother Nature gives you.”

In preparation for flight tests, Virgin Galactic officials also keep an eye on clouds, Whitesides said.

Thursday Feb. 21 is expected to be cloudy and windy in Mojave. Forecasts call for sunshine and mild winds on Friday Feb. 22.