The flamboyant British entrepreneur admitted his famed Virgin Galactic spaceship has struggled because of the relatively untested nature of its technology, which has caused repeated delays to its inaugural mission.
"The biggest worry I had was re-entry. NASA has lost about 3 per cent of everyone who's gone into space, and re-entry has been their biggest problem," Branson told the Guardian in an interview.
"For a government-owned company, you can just about get away with losing 3 per cent of your clients. For a private company you can't really lose anybody. Nobody we met had anything but the conventional risky re-entry mechanism that NASA had.
"We were waiting for someone to come up with one that was foolproof," he added.
Branson insisted his plan is credible and the first flight, reaching 62 miles above the earth, will take place.
"Everybody who signs up knows this is the birth of a new space programme and understands the risks that go with that. But every person wants to go on the first flight," he said.
Almost 700 people, including actors Tom Hanks and Angelina Jolie, have paid between 125,000 pounds and 155,000 pounds to book a two-hour journey on Virgin Galactic's SpaceShipTwo, which will include a planned five minutes of weightlessness.
Despite Branson's insistence since 2007 that the first six-passenger flight is imminent, the service has completed only three test flights with a peak altitude of little more than 13 miles.
To obtain the necessary US Federal Aviation Administration licence, the craft will need several tests at its full speed and 62-mile height.