Virgin Galactic completed its first powered flight in nearly four years on Thursday when Richard Branson's space company launched its Unity spacecraft by rocket power, reaching supersonic speeds before safely landing.

@virgingalactic: VSS Unity went supersonic and will be landing shortly #SpaceShipTwo

Unity took off from the Mojave Air and Space Port, lifted by the jet-powered mothership Eve. The carrier aircraft lifted Unity to an altitude of 46,500 feet above the desert. Eve released Unity from under its wing and, with a two-member crew of Mark Stucky and Dave Mackay, Unity's rocket motor roared to life. The rocket screamed into a steep climb as the engine burned for 30 seconds, pushing Unity past the speed of sound to Mach 1.87.

"On rocket shutdown, Unity continued an upwards coast to an apogee of 84,271 feet before readying for the downhill return," Virgin Galactic CEO George Whitesides said in a statement.

The Unity craft the turned and glided back to land at Mojave, with Eve touching down soon after. It was the fifth powered test flight of the SpaceShipTwo design, and the first since the fatal crash of Spaceship Enterprise on Oct. 31, 2014.

@virgingalactic: Touch down. Congratulations Mark "Forger" Stucky and Dave Mackay for a great milestone test flight #SpaceShipTwo

The spacecraft underwent extensive engine testing and seven glide tests before Virgin Galactic said it was ready for a powered test flight — a crucial milestone before the company begins sending tourists to the edge of the atmosphere.

The original SpaceShipTwo craft was built by experimental aircraft developer Scaled Composites. In 2016, Virgin Galactic unveiled the version of the SpaceShipTwo design on which Unity is based, built by The Spaceship Company. A subsidiary of Virgin Group, The Spaceship Company made alterations to the design, intending to avoid a repeat of the 2014 accident. The company is also building two more spaceships, intended to become part of the Virgin fleet for taking people to the edge of space.