Development of the SpaceShipTwo has suffered a series of setbacks in the past few years, most notably an explosive fatal crash in October 2014.
The commercial spacecraft is due to be launched at the Mojave Air and Space Port in California Friday, Branson told TV program Good Morning Britain. A seat on board costs $250,000.
Branson said the experimental space project was “nearly back on track” after delays surrounding the crash and subsequent investigation.
“I must admit, there were moments when we wondering whether we would carry on,” he added.
Branson said the death of Virgin Galactic co-pilot Mike Alsbury two years ago and three others during development stages in 2007 are unfortunately “part of the price of trying to achieve things that haven’t been achieved before”.
The project was almost completely canceled when the SpaceShipTwo exploded 47,000 feet above the California desert in 2014 , killing Alsbury and severely injuring pilot Pete Siebold.
Investigators from the National Transportation Safety Board found deficiencies in the braking system caused the crash.
Virgin Galactic say the new and improved SpaceShipTwo will remain on the ground “as we run her through full-vehicle tests of her electrical systems and all her moving parts.”
“We already know these things work individually, but one can’t assume they will all work together – that must be tested and verified. We’ll do so quickly, but we won’t cut corners,” a statement reads.
The project so far
Spaceflight with Virgin Galactic will be a two-step journey. A mothership, the four-engine jet WhiteKnightTwo, flies passengers the first 50,000 feet before the eight-person SpaceShipTwo continues the journey to Earth’s boundary with space.
Predicted to give tourists about five minutes of weightlessness, the shuttle has a winged design allowing it to decelerate safely and accurately back to Earth.
Testing on materials first began shortly after the company launch in 2004. In 2010, Branson said SpaceShipTwo was “18 months away from taking people into space”.
He also hoped the maiden flight would eventually lead to hotel getaways on the moon.