Virgin Galactic has shown the first firing of its spaceplane's chemical rocket engine was no fluke, following last month's effort with another successful outing in California. The latest test flight took the tourist-carrying space vehicle a little closer to space, literally and figuratively, with engineers now poring over data with an eye to the next round of testing.

Where some private space companies, such as Blue Origin, imagine firing tourists into space with conventional launch vehicles that blast off from the ground, Virgin Galactic's SpaceShipTwo VSS Unity works a little differently.

During the test flight last month, it was carried into the air by a mothership called WhiteKnightTwo and released at an altitude of 46,500 ft (14,173 m). Seconds later, its hybrid rocket engine was fired up for around 30 seconds to propel the plane to roughly Mach 1.9 (2,328 kph/1,446 mph) and an altitude of 84,271 ft (25,686 m).