(CNN) — Virgin Galactic's supersonic space plane soared into the upper reaches of Earth's atmosphere Thursday for a milestone flight. The successful flight indicates the company is not far off from sending tourists to space.
The rocket-powered plane, VSS Unity, was flown by two veteran pilots to a maximum altitude of 51.4 miles, surpassing the 50-mile mark that the US government recognizes as the edge of space. It uses the 50-mile mark to award astronaut wings.
"I hope we go to space today," he said ahead of liftoff.
It was the fourth powered test flight for VSS Unity and the closest yet to mimicking the flight path that it is expected to one day take on commercial missions. Its success means the company could be just months away from taking up its first load of tourists, a goal Virgin Galactic has worked toward for 14 years.
Rather than aiming for space using a NASA-esque vertically launched rocket, Virgin Galactic uses a rocket-powered space plane dubbed VSS Unity, a craft more comparable to the supersonic X planes developed by the US military.
VSS Unity took off attached to its mothership, WhiteKnightTwo. Then, about 43,000 feet in the air, VSS Unity's pilots commanded the plane's release. After a few seconds of coasting, VSS Unity's rocket engine engaged and drove the vehicle directly upward at supersonic speeds.
In addition to the test pilots, a flight test dummy and four unnamed research payloads from NASA's Flight Opportunities Program were onboard to help simulate the weight distribution of having passengers on board.
Virgin Galactic has not said when it plans to begin commercial flights.
"Incremental flight test programs are by definition open-ended and, to a great extent, each test depends on the data from the test that precedes it," the company said. "There is no guarantee that everything will work perfectly first time and, like all programs seeking to take bold steps, we will inevitably have times when things don't go as planned."
Branson's space venture suffered a major setback in 2014 when its first space plane, VSS Enterprise, broke apart during a test flight, killing co-pilot Michael Alsbury and injuring pilot Peter Siebold.
The tragedy spurred critics of space tourism who have deemed such projects irresponsibly risky. But Virgin Galactic bounced back.
The company is squared up to compete directly with Blue Origin, the space company founded by Amazon billionaire Jeff Bezos in 2000 to offer suborbital tourism flights.
Both companies are still in the testing phase. And Blue Origin — which plans to fly tourists on an automated, vertically launched rocket — has yet to conduct a crewed flight or begin selling tickets.
Virgin Galactic says about 600 people have reserved tickets, priced between $200,000 and $250,000, to ride aboard its supersonic plane. Some have waited over a decade for their shot.
When asked about Virgin Galactic's competitors in a recent interview with CNN Business, Branson said it was not a "race."
"Safety's all that matters if you're putting people into space," he said.
Branson, who plans to be on the first passenger trip aboard VSS Unity, has said he hoped Virgin Galactic's pilots would reach space before December 25.
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