Virgin Galactic’s tourist-carrying spaceplane has taken a step closer to entering service after its chemical rocket engine was fired for the first time in the skies over the Sierra Nevada Mountains in California. With test pilots Mark “Forger” Stucky and Dave Mackay at the controls, the 60-ft-long (18 m) SpaceShipTwo VSS Unity pegged the speedometer at Mach 1.87 (1,424 mph, 2,290 km/h) within 30 seconds of igniting its engine.