Richard Branson is fighting a rearguard action to defend his troubled space program, Virgin Galactic, which has come in for much criticism in recent weeks, with increasing numbers of commentators questioning whether it will ever get off the ground.

He insisted that the first flight will be ready to go in August, and that he will be on it, with his children.

But he admitted there were risks involved.

In an interview with Guardian Weekend Magazine, Sir Richard said: "Everybody who signs up knows this is the birth of a new space programme and understands the risks that go with that. The biggest worry I had was re-entry. NASA has lost about three per cent of everyone who's gone into space, and re-entry has been their biggest problem. For a government-owned company, you can just about get away with losing three per cent of your clients. For a private company you can't really lose anybody."

And if shooting people into space seems like a rather sweetly naive and childlike idea, then perhaps we shouldn't be surprised to learn that Richard Branson has admitted he got the idea for his commercial space flight venture during a phone-in on a children’s TV show.The Virgin boss told British TV host Jonathan Ross that he first thought about the idea in 1988 on the BBC Saturday morning show 'Going Live' when someone suggested it during a viewer phone-in.

He also brushed off criticism of his venture - and, in true Branson style, said that he hoped to build "Virgin hotels in space."

Appearing on the chat show, he says: “You never know what sparks things off in your mind but as as result of that children's TV show we registered the name Virgin Galactic Airways. Over the next decade I started travelling around the world meeting technicians and engineers to see if we could find a genius who could build a spaceship that could take you and me into space.”Sir Richard says the idea was the “beginning of a whole new era of space travel” and was “the most ridiculously exciting thing that I’ve done in my lifetime”.He added: “If we can get enough people wanting to fly it then we can start building Virgin hotels in space, we can start doing trips to Mars."

He also confirmed, to Digital Spy, that he has booked Lady GaGa to play live on the inaugural flight.

Hollywood stars Tom Hanks and Angelina Jolie are among around 700 people who have paid up to £155,000 to take part in a two-hour flight aboard Branson's SS2 shuttle.

Along with the flight – which aims to reach 62 miles above earth - those aboard will experience about five minutes of weightlessness as part of the package.

So far, three test flights of the SS2 have only managed altitude of around 71,000ft - approximately 13 miles.